[ RESEARCH 63, 8563–8572, December 15, 2003] Perspectives in Cancer Research

Harnessing for Improved Anticancer Therapy

David J. Waxman and Pamela S. Schwartz Division of and Molecular Biology, Department of Biology, Boston University, Boston, Massachusetts

Abstract 8 and 9, are activated by two alternative pathways, both of which lead to apoptotic cell death. One pathway is triggered by Advances in our understanding of the mechanisms by which tumor cells cellular stresses that induce changes in mitochondrial function and is detect drug-induced DNA damage leading to apoptotic death have aided primarily associated with the activation of 9 (“intrinsic” in the design of novel, potentially more selective strategies for cancer apoptotic pathway; Refs. 7, 8). The second (“extrinsic”) pathway treatment. Several of these strategies use proapoptotic factors and have 1 shown promise in sensitizing tumor cells to the cytotoxic actions of tradi- activates caspase 8 and proceeds via the formation of a DISC at the tional cancer chemotherapeutic drugs. Although antiapoptotic factors are cell surface, which provides a mechanism for aggregation and auto- generally regarded as poor prognostic factors for successful cancer chem- cleavage (autoactivation) of the caspase (Ref. 9; Fig. 1). As discussed otherapy, strategies that use antiapoptotic factors in combination with below, anticancer drugs with diverse mechanisms of action can acti- suicide or other gene therapies can also be considered. The introduction of vate both apoptotic pathways. Moreover, in both pathways the initi- antiapoptotic factors that act downstream of drug-induced mitochondrial ator caspase cleaves and thereby activates downstream, effector transition delays, but does not block, the ultimate cytotoxic response to caspases, such as caspase 3, caspase 7, and others. This caspase cancer chemotherapeutic drugs that activate a mitochondrial pathway of cascade ultimately leads to proteolytic cleavage of a variety of cellular cell death. Recent studies using the cytochrome P-450 prodrug cyclophos- and induces the broad range of morphological changes that phamide exemplify how the antiapoptotic, caspase-inhibitory baculovirus p35 can be combined with P-450 gene-directed enzyme prodrug are characteristic of cells undergoing apoptosis. therapy to prolong localized, intratumoral production of cytotoxic drug metabolites without inducing tumor cell drug resistance. This model may Mitochondrial Cell Death Pathway be adapted to other gene therapies, including those that target death receptor pathways, to maximize the production of soluble, bystander In stress-induced cell death, signals received by mitochondria stim- cytotoxic factors and prodrug metabolites and thereby amplify the ther- ulate mitochondrial membrane permeabilization and release several apeutic response. proapoptotic factors into the cytosol (10–12). Key mitochondrial factors released in this manner include cytochrome c (13), certain Introduction caspases (14), AIF, which induces condensation and DNA fragmentation (15, 16), and Smac/Diablo, which neutralizes IAP Aberrant regulation of cell growth has traditionally been viewed as proteins and allows caspase activation to proceed (Refs. 17–19; Table the major underlying mechanism for tumor formation; however, it is 1). Mitochondrial release of cytochrome c triggers formation of the becoming increasingly clear that cellular changes that lead to inhibi- apoptosome, an oligomeric, multiprotein complex comprising cyto- tion of apoptosis play an essential role in tumor development (1). chrome c, ATP, caspase 9, and the scaffold protein Apaf-1, which Many cancer chemotherapeutic drugs activate apoptotic mechanisms stimulates/amplifies the activation of caspase 9 and downstream of tumor cell death, suggesting that factors that impair programmed apoptotic events (20, 21). cell death contribute to the resistance of tumor cells to cytotoxic drug Mitochondrial cytochrome c release and apoptosome formation are treatment (2). Elucidation of the apoptotic pathways that are triggered subject to regulation by proteins belonging to the Bcl-2 family, by anticancer therapies is thus an important area of study that may comprising at least 16 family members. The Bcl-2 family includes provide insights into the underlying causes of intrinsic and acquired proapoptotic members, such as Bax and Bid, which promote mito- drug resistance and facilitate the development of novel anticancer chondrial release of proapoptotic factors; and anti-apoptotic members, therapies. This review discusses recent advances in this field and such as Bcl-2, Bcl-X , and Mcl-1, which block factor release (22). A highlights novel therapeutic approaches that use proapoptotic factors L positive correlation between the expression of Bcl-2 and a chemore- to increase responsiveness to classic anticancer drugs, as well as sistant phenotype has been observed in many human tumors, suggest- antiapoptotic factors to optimize suicide and other gene-based thera- ing that Bcl-2 and other family members are important determinants pies for cancer treatment. of the clinical responsiveness to a wide range of anticancer chemo- Role of Caspases in Tumor Cell Death therapeutic agents (22).

Many commonly used anticancer drugs induce tumor cell apo- Receptor-mediated Cell Death Pathway ptosis, a process that is mediated by caspases, a ubiquitous family of cysteine proteases that includes both upstream (initiator) and down- Receptor-mediated cell death is initiated by the binding of a death- stream (effector) caspases (3, 4). Caspases are synthesized in an inducing ligand to a cysteine-rich repeat region in the extracellular inactive proform that is activated by proteolytic cleavage at two or domain of a death receptor. This, in turn, leads to activation of more sites. Cleavage at one site generates the large and small subunits trimerized death receptor at the cell surface and activation of caspase of the mature, active protease, whereas cleavage at a second site removes the prodomain (3, 5, 6). The initiator caspases, typically 1 The abbreviations used are: DISC, death-inducing receptor signaling complex; AIF, apoptosis-inducing factor; IAP, inhibitor of apoptosis; Apaf-1, apoptosis protease-activat- ing factor 1; TNF, tumor factor; TRAIL, TNF-related apoptosis-inducing ligand; Received 6/17/03; revised 9/10/03; accepted 9/25/03. FADD, Fas-associated death domain-containing protein; FLIP, Fas-associated death do- Grant support: NIH Grant CA49248 (to D. J. W.). main-like ICE inhibitory protein; TRAF, TNF receptor-associated factor; NF-␬B, nuclear Requests for reprints: David J. Waxman, Department of Biology, Boston University, factor-␬B; DNA-PK, DNA-dependent protein kinase; GDEPT, gene-directed enzyme 5 Cummington Street, Boston, MA 02215. Fax: (617) 353-7404; E-mail: [email protected]. prodrug therapy; HSV-tk, herpes simplex virus-thymidine kinase. 8563

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. APOPTOTIC FACTORS AND CANCER GENE THERAPY

Fig. 1. Intrinsic and extrinsic pathways of apoptotic cell death. The intrinsic pathway of apoptotic cell death is mediated by changes in mitochondrial function, is regulated by Bcl-2 family members, and is associated with the activation of the initiator caspase 9. The extrinsic apoptotic pathway is initiated by the formation of a death-inducing cell surface receptor signaling complex and leads to activation of the initiator caspase 8. In both pathways the activation of an initiator caspase, i.e., caspase 8 or caspase 9, induces the activation of effector caspases. These downstream caspases, in turn, carry out proteolytic cleavage of various cellular proteins and induce the large number of morphological changes that are characteristic of cells undergoing apoptosis. Pro-apoptotic factors are indicated in italic, and antiapoptotic factors are indicated in bold. The antiapoptotic factors Bcl-2 and Bcl-XL inhibit mitochondrial-mediated apoptosis. In type II cells (see text), Bcl-2 can inhibit caspase 8-mediated apoptosis by blocking action of the truncated Bid fragment tBid. IAPs induced downstream of NF-␬B suppress apoptosis by binding directly to and inactivating caspases. IAPs partially inhibit stress-induced apoptosis while fully inhibiting receptor-mediated apoptosis. FLIPs interfere with the recruitment and activation of caspase 8 and thereby inhibit receptor-mediated apoptosis. Decoy receptors bind to death-inducing ligands but do not transmit an intracellular death signal, thereby inhibiting death ligand-induced apoptosis. See text and Table 1 for further details.

8-dependent cell death, as outlined below (Fig. 1). Death receptor ing COOH-terminal death domain of an adaptor protein such as ligands include TNF-␣, , and TRAIL, each associated with FADD (24). The adaptor protein additionally contains a death effector its own specific death receptor. These death receptor-activating li- domain (25) that binds to the NH2 terminus of the caspase 8 prodo- gands are expressed in both membrane-bound and soluble forms and main, thus facilitating DISC formation and proteolytic autoactivation share a homologous 150- region that interacts with, and of caspase 8. may serve to aggregate, the death receptor (23). Each death receptor Two classes of cells can be distinguished based upon their response contains a cytoplasmic tail “death domain” that binds the correspond- to factors that induce death receptor-dependent cell death (26). In type

Table 1 Factors involved in tumor cell apoptosis Factor/Complex Function Reference Apaf-1 (apoptosis protease-activating factor 1) Adaptor protein of the apoptosome. Critical for assembly of complex leading to binding of (15, 16) caspase 9, cytochrome c, and ATP, and resulting in caspase 9 activation. AIF (apoptosis-inducing factor) Bcl-2-regulated mitochondrial protein that induces chromatin condensation and DNA (15, 16) fragmentation. Apoptosome Multi-protein complex comprising the adaptor protein Apaf-1, caspase 9, cytochrome c, and (20, 21) ATP. Bcl-2 family Family of proteins comprising pro- and antiapoptotic members. Regulates release of (22) proapoptotic factors from mitochondria. Caspases Cysteine proteases whose activation leads to proteolytic cleavage of various cellular proteins (3) and induces the large number of morphological changes characteristic of cells undergoing apoptosis. DED (death effector domain) Protein domain that regulates programmed cell death. The DED contained in FADD facilitates (25) interaction of with caspase 8 to mediate DISC formation. Some DED- containing proteins can inhibit DISC formation. Death receptors Cell surface proteins that bind to extracellular death-inducing ligands, aggregate, and induce an (3) intracellular cascade of apoptotic events. DISC (death-inducing signaling complex) Multi-protein complex comprising a death receptor and ligand, an adaptor protein, and cas- (2) pase 8. FADD (Fas-associated death domain-containing protein) Adaptor protein associated with death receptors. Contains both a “death domain” (DD), which (2) interacts with the receptor, and a DED, which interacts with caspase 8. FLIP (Fas-associated death domain-like ICE inhibitory protein) Cellular protein structurally similar to caspase 8. Interferes with recruitment and activation of (23) caspase 8 by death receptors. IAP (inhibitor of apoptosis) Protein that binds directly to and inactivates caspases. (19) Smac/Diablo Bcl-2-regulated mitochondrial protein that inactivates certain IAPs. (17, 18) TRAF ( receptor-associated factor) Family of adaptor proteins that couples the tumor necrosis factor receptor family and can (39) convey either a death signal or a survival signal. 8564

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. APOPTOTIC FACTORS AND CANCER GENE THERAPY

I cells, the binding of a death receptor ligand activates caspase 8 to a TRAIL decoy receptor (44), and FLIP (45), leading to a block in level that is sufficiently high to directly initiate a downstream caspase caspase 8 cleavage and conferring resistance to Fas ligand and TNF-␣ cascade. In type II cells, however, the cellular level of activated (45). NF-␬B also induces the Bcl-2 homologue A1/Bfl-1, which caspase 8 is too low to propagate the caspase cascade and the ensuing blocks etoposide-induced apoptosis by inhibiting mitochondrial cyto- apoptotic response in the absence of a mitochondria-dependent am- chrome c release and caspase 3 activation (46). cIAP1 bound to TNF plification step. This cross-talk from the death receptor pathway to the receptor signaling complexes can induce ubiquitination and degrada- mitochondrial apoptotic pathway is initiated by caspase 8 cleavage of tion of the associated TRAF adapter protein, thereby interrupting TNF the cytosolic, proapoptotic Bcl-2 family protein Bid, which translo- induction of NF-␬B and potentiating TNF-induced apoptotic re- cates to mitochondrial membranes and induces cytochrome c release sponses (47). (Refs. 27, 28; Fig. 1). The resulting formation of the apoptosome, activation of caspase 9 and the downstream apoptotic responses seen Induction of Apoptosis by Drug-induced DNA Damage in death receptor ligand-treated type II cells can be blocked by mitochondrial antiapoptotic factors such as Bcl-2 (26, 28, 29). Pre- The association between drug-induced DNA damage, apoptosis, sumably, type II cells differ from type I cells by having lower levels and tumor remission is well-established for hematological malignan- of caspase 8 or one of the other factors required for formation of the cies and for some, but not all, solid tumors (48). Recent studies have DISC complex. Alternatively, the mitochondrial dependence of death provided insight into the question of how tumor cells detect nuclear receptor-induced apoptosis in type II cells may result from the ex- DNA damage induced by cancer chemotherapeutic drugs and how this pression of an apoptosis resistance factor that partially blocks caspase leads to the induction of apoptosis. Drugs such as methotrexate (49), 8 activation, rendering the cells dependent on mitochondrial amplifi- betulinic acid (50), and cyclophosphamide (51) activate the mitochon- cation of the initial death signal (28). drial/caspase 9 pathway of cell death, whereas other drugs, including doxorubicin (50), etoposide, teniposide (52), 5-fluorouracil (53, 54), Cellular IAPs cytarabine (55), and cisplatin (56), primarily activate the death recep- tor/caspase 8 pathway. In some cases the pathway of apoptotic death The basal level of apoptosis is tightly controlled in mammalian is tumor cell type dependent, as reported for paclitaxel (Taxol; Refs. cells by endogenous IAPs, several of which may become dysregulated 57, 58) and the prodrug ganciclovir (59, 60). Drug-induced cell death and have been implicated in tumorigenesis and chemoresistance. IAP may also involve other pathways that diverge in one or more respects proteins inhibit mitochondrial- and death receptor-induced apoptosis, from the classical apoptotic pathways, as suggested for paclitaxel (61, in some cases by binding directly to and inactivating the target 62) and tamoxifen in the case of estrogen receptor-positive tumor cells caspase (19). In the case of XIAP, mitochondrial cell death is blocked (63). by direct IAP inhibition of cytochrome c-induced caspase 9 activation. The sensing of DNA damage in the form of single-strand DNA and By contrast, caspase 8 is resistant to the inhibitory action of XIAP, double-strand DNA breaks is an intricate process that is only partially which suppresses death receptor apoptosis at the downstream, caspase understood. DNA-binding factors that may serve as sensors of DNA 3 activation step (30). One IAP, survivin, is frequently overexpressed damage include the RAD17-RFC and Rad9-1-1 supercomplex for in tumor cells (31). IAP activity is regulated by Smac/Diablo, which single-strand DNA breaks, and the KU subunit of DNA-PK, the upon release from mitochondria inhibits IAP activity, thereby facili- MRE11-Rad50-NBS1 complex, and the tumor suppressor BRCA1 for tating caspase 9 activation (17, 18). Moreover, IAPs with a RING double-strand DNA breaks (64–67). Directly downstream of these finger domain, such as cIAP1 and cIAP2, have intrinsic ubiquitin proteins are three enzymes belonging to the phosphatidylinositol protein ligase (E3) activity, which facilitates their auto-ubiquitination 3-kinase family: DNA-PK, ATM, and ATR. These enzymes, often and degradation and may lead to IAP down-regulation in response to referred to as transducers, relay and amplify the DNA damage signal certain apoptotic stimuli (32). by phosphorylation of a small group of effector kinases. These include FLIPs are antiapoptotic factors that contain death effector domain the serine/ kinases Chk1 and Chk2 (65, 66) and the ubiqui- sequences and thus share structural similarity with caspase 8. This tously expressed tyrosine kinase c-Abl (Refs. 68, 69; Fig. 2). Phos- feature enables FLIPs to interfere with the recruitment and activation phorylation of these effector kinases, in turn, leads to phosphorylation of caspase 8 by ligand-activated death receptors, thereby blocking of various downstream targets, including the factors , receptor-mediated apoptosis (Ref. 23; Fig. 1). Receptor-mediated cell p73, and E2F-1 (70–73) and may result in DNA repair, cell cycle death can also be inhibited by the expression of decoy receptors, arrest, or apoptosis. Interestingly, several of the transducers and which bind death receptor ligands but have a truncated (or absent) downstream effectors in this pathway, including ATM, ATR (66), and cytoplasmic death domain and are therefore unable to transmit an p53 (74), may also serve as direct DNA damage sensors, highlighting intracellular death signal. Decoy receptors inhibit apoptosis induced the complexity of the overall DNA damage response pathway. Phos- by TRAIL [decoy receptors DcR1 and DcR2 (33, 34)] and Fas ligand phorylation of p53 enhances the DNA damage response by multiple [decoy receptor DcR3 (35, 36)]. TRAIL decoy receptors DcR1 and mechanisms, including trans-activation of p21, a potent inhibitor of DcR2 are down-regulated in tumor cells but not normal cells (37, 38) cyclin-dependent kinase and inducer of cell cycle arrest (70, 75, 76). and may protect normal cells from TRAIL-induced apoptosis. By Effector kinase-catalyzed serine phosphorylation of p53’s trans-acti- contrast, the Fas decoy receptor DcR3 is overexpressed in lung and vation domain blocks the binding of Mdm-2, an E3 ubiquitin protein colon tumors, suggesting a role in tumor cell resistance to Fas ligand ligase that targets p53 for degradation (65, 70, 76). The (35). resulting increase in p53 protein stability increases the transcription of In contrast to the proapoptotic responses that are stimulated by Fas p53 target , including those encoding the proapoptotic Bcl-2 and TRAIL receptor, TNF receptor signaling often leads to enhanced family members Bax, Noxa (77, 78), and PUMA (79). These proteins, tumor cell survival and proliferation. TNF receptor recruitment of in turn, translocate from the cytosol to the mitochondrial outer mem- TRAF adapter proteins leads to the activation of NF-␬B (39), which brane and induce mitochondrial transition, apoptosome formation, and acts as a survival factor and a suppressor of apoptosis (40, 41). NF-␬B caspase 9-dependent apoptosis. p53 can also down-regulate Bcl-2 (80, suppresses apoptosis by multiple mechanisms. These include up- 81) and stimulate expression of enzymes such as proline oxidase, regulation of anti-apoptotic factors, such as TRAFs, IAPs (42, 43), which increases mitochondrial production of cytotoxic, reactive oxy- 8565

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. APOPTOTIC FACTORS AND CANCER GENE THERAPY

NF-␬B and AP-1 (52, 101). This in turn leads to the killing of tumor cells in an autocrine or paracrine fashion (102–104). This conclusion is supported by the finding that 5-fluorouracil-dependent apoptosis of colon carcinoma cells is blocked by anti-Fas (53, 102, 103). In several tumor cell lines, however, anti-Fas has no effect on apoptosis induced by cisplatin, doxorubicin, and etoposide (24), indicating that drug-induced apoptosis proceeds in a Fas-independent manner. Rather, in this system tumor cell death is proposed to proceed by a FADD-mediated, ligand-independent receptor aggregation mech- anism (24). Additional mechanisms may also apply, as suggested by the ability of cisplatin to down-regulate cFLIP expression, leading to an increase in tumor cell sensitivity to Fas-induced apoptosis (105).

Fig. 2. DNA damage leads to induction of apoptosis. In this simplified scheme, DNA damage resulting in either single-strand breaks (SS) or double-strand breaks (DSB)is Proapoptotic Cancer Therapies sensed by factors that recognize and bind to damaged DNA, such as the RAD17-RFC and Rad9-1-1 supercomplex, BRCA1, and the Ku subunit of DNA-PK. These damage sensors Several anticancer therapies are currently being developed with the then transduce the signal into a cellular response by activation of the phosphatidylinositol goal of modulating the expression or activity of factors that contribute 3-kinase family members DNA-PK, ATM, and ATR (see text). These enzymes, in turn, initiate a phosphorylation (P) cascade that involves the serine/threonine kinases Chk1 and to tumor cell apoptosis. In one approach, enhanced chemosensitivity Chk2 and the ubiquitously expressed tyrosine kinase c-Abl and their downstream targets, can be achieved by gene therapies delivering transcription factors that including the transcription factors p53, p73, and E2F-1. Phosphorylation of these mole- respond to DNA-damaging agents, such as p53 (106–108) and E2F-1 cules may alter their transcriptional activity, resulting in the trans-activation (T)of numerous genes, some of which are shown in this simplified scheme. Several antiapo- (109–111). Chemo-responsiveness can also be increased by gene ptotic molecules are down-regulated in response to DNA damage, including Bcl-2 and therapy using the adenovirus E1A protein, which imparts a range of Mcl-1 (inverted arrow). Other pathways, as well as cross-talk within the pathways shown, is known to occur. See text and references therein for further details. antitumor effects, including induction of apoptosis (112), and can be delivered in a tumor-selective manner using conditionally replicating adenoviral vectors (113). In another approach, proapoptotic genes can gen species (82, 83). Collectively, these cellular events link the be introduced into tumor cells to enhance chemosensitivity. For ex- detection of DNA damage to p53-dependent activation of the mito- ample, cellular caspase activity can be increased by delivery of a chondrial apoptotic pathway (Fig. 2). full-length zymogen form of a caspase cDNA (114, 115) or by In view of the functional absence of p53 in the majority of human delivery of a mutant, inhibitory form of the IAP survivin (116). The tumors (84), it is important to identify the p53-independent pathways mitochrondrial cell death pathway can be selectively targeted by through which DNA-damaging agents induce tumor cell apoptosis. delivery of a proapoptotic protein such as Apaf-1 (117) or Bax, which One pathway involves the tyrosine kinase c-Abl, which when acti- counters the chemoresistant effects of Bcl-2 (118, 119). Alternatively, vated by DNA-PK or ATM generates apoptotic signals similar to p53 antiapoptotic proteins such as Bcl-2 or Bcl-XL can be down-regulated by activation of the stress-activated protein kinase and p38 MAP using antisense oligonucleotides (120–122), by intracellular expres- kinase pathways and by inhibition of phosphatidylinositol 3-kinase sion of anti-Bcl-2 antibodies (123), or by introduction of Bcl-2 siRNA (68, 85). A second p53-independent apoptotic pathway involves the (124). These latter studies reveal a striking role for Bcl-2 in suppress- transcription factor E2F-1, which is stabilized in a manner similar to ing p53-dependent apoptosis, as demonstrated by the massive apo- p53 (86) and is redirected from cell cycle progression to apoptotic ptosis of colorectal carcinoma cells that occurs upon silencing of in response to DNA damage (87). E2F-1 plays an Bcl-2 expression, even in the absence of genotoxic agent treatment important role in the initiation of DNA damage-induced apoptosis in (124). Novel small molecule inhibitors selective for Bcl-2 or Bcl-XL p53-deficient tumor cells; its actions include (Fig. 2): (a) transcrip- may also be useful (125, 126). Bcl-2 and Bcl-XL inhibitory strategies tional activation of Apaf-1, leading to direct activation of caspase 9 in may be particularly effective when combined with anticancer drugs the absence of mitochondrial damage and cytochrome c release (88, that induce a mitochondrial cell death pathway, such as cyclophos- 89); (b) transcriptional induction of caspase proenzymes (90), which phamide (51, 121). helps to overcome endogenous inhibitory factors (e.g., IAPs) and Gene therapies that deliver a cell death receptor ligand such as sensitizes tumor cells to apoptotic signals; (c) repression of the anti- TRAIL (127, 128) may be used to enhance the death receptor- apoptotic Bcl-2 family member Mcl-1 (91); and (d) induction of the dependent cell death pathway and increase responsiveness to tradi- p53 tumor suppressor family member p73 (87, 92), which serves as a tional anticancer agents (103, 129, 130). The expression of TRAIL proapoptotic factor in DNA-damaged cells and is an important che- confers bystander cell toxicity, presumably via a paracrine mechanism mosensitivity determinant in human tumor cells (93). The protein (128). Recombinant TRAIL induces tumor regression in preclinical stability, nuclear matrix association, responsiveness to p300-depend- models (131), and in contrast to Fas ligand and TNF-␣, exhibits little ent acetylation, and apoptotic activity of p73 are all enhanced by toxicity to normal tissues because of the host cell protective effects of c-Abl, which directly interacts with and catalyzes p73 tyrosine phos- TRAIL decoy death receptors, which are selectively down-regulated phorylation (Refs. 94–96; Fig. 2). in many tumor cells (37, 38). Death receptor and mitochondrial Several hypotheses have been advanced to explain the activation of pathways of apoptosis may also be targeted simultaneously by com- caspase 8-dependent apoptotic responses in tumor cells treated with bining TRAIL with Bax gene delivery (132). In an alternate approach, DNA damage-inducing anticancer drugs such as doxorubicin, 5- TRAIL receptor DR4-deficient tumor cells can be sensitized to fluorouracil, and cisplatin. One proposal is based on the observation TRAIL by gene therapy using p53, which up-regulates DR4 expres- that in certain tumor cell types these drugs induce the expression of sion in tumor cells (133). Tumor cells can also be sensitized to TRAIL Fas ligand and stimulate a p53-dependent increase in cell surface by overexpression of Smac/Diablo, the neutralizing inhibitor of IAPs, expression of Fas (97, 98) and the TRAIL receptors DR4 and DR5 or by treatment with cell-permeable Smac/Diablo peptides, which (99, 100). Drug-induced Fas ligand gene expression may be induced induce the release of endogenous mitochondrial Smac/Diablo and lead by DNA damage, leading to activation of the transcription factors to synergistic activation of multiple caspases (134–136). 8566

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. APOPTOTIC FACTORS AND CANCER GENE THERAPY

Gene therapies can also be designed to block the antiapoptotic, Antiapoptotic Strategies to Enhance P450 GDEPT and Other tumor cell-protective NF-␬B inductive response to cytotoxic drug Gene Therapies treatment. This may be accomplished by delivery of a dominant- negative, proteolytically stable “super repressor” of I␬B, which in Proapoptotic gene therapies, such as the Bax and p53 gene therapies some tumor cell types blocks drug-induced NF-␬B activation and noted above, display intrinsic antitumor activity. Moreover, these increases chemosensitivity to anticancer drugs and to TNF-␣ (137, proapoptotic therapies may confer additional therapeutic benefit by 138). In the case of hepatocellular carcinoma, the I␬B super-repressor lowering the threshold drug concentration required for traditional also enhances TNF-␣-induced apoptosis but has an undesirable, an- anticancer agents to induce tumor cell death. However, the combina- tiapoptotic effect on chemotherapy-induced cell death (139). NF-␬B tion of a proapoptotic therapy with suicide gene therapy, such as activation may also be blocked by certain proteasome inhibitors now P-450 GDEPT, is likely to be counterproductive, because it will under development for cancer treatment (140, 141) and by the low shorten the life span of the prodrug-activating tumor cell and conse- molecular weight protein kinase C inhibitor Go6976, which induces quently limit net production and release of active drug metabolites regression of established mouse mammary tumors by blocking NF-␬B (166). Agents that deplete cell-protective small molecules, such as activation and reinstating an apoptotic program of gene expression glutathione, or strategies that decrease the expression or activity of (142). protective enzymes, such as glutathione S-transferase (167Ð169) or aldehyde dehydrogenase (170) may be used to sensitize tumor cells to cyclophosphamide and other alkylating agents (170Ð173). However, GDEPT Using Cytochrome P-450 by enhancing tumor cell chemosensitivity, these modulation strategies Prodrug-activation gene therapy, also referred to as suicide gene will necessarily undermine the effectiveness of a GDEPT strategy: the therapy or GDEPT, has been widely studied as a strategy to increase life span of tumor cells that express the suicide gene will be shortened, the sensitivity of cancer cells to apoptosis induced by anticancer and net production and release of active drug metabolites will conse- prodrugs (143, 144). Introduction of a suicide gene using a suitable quently be diminished, thus limiting the bystander cytotoxic effect gene therapy vector provides the tumor cell with the capacity for that is vital to the overall success of the GDEPT approach. On the localized prodrug activation, thereby restricting production of the other hand, any effort to suppress apoptosis of those tumor cells that toxic drug metabolite to the tumor tissue. GDEPT can impart a strong express the suicide gene increases the risk of generating an aggressive, bystander cytotoxic response because of the diffusion of activated drug-resistant tumor. drug metabolites from a transduced tumor cell into neighboring, naõ¬ve A general solution to this problem has been proposed based on the tumor cells that do not express the prodrug-activation enzyme (145). results of a P-450 GDEPT study using cyclophosphamide. Specifi- In contrast to many other cancer gene therapies, therefore, GDEPT cally, the baculovirus-encoded pan-caspase inhibitor p35 (174) was does not require the genetic modification of each individual tumor shown to slow down, but not block, the death of tumor cells that cell. Widely studied suicide gene therapy systems include HSV-tk in express P450 in a manner that substantially increased net production combination with the antiviral prodrug ganciclovir (146, 147) and the of bystander, cytotoxic cyclophosphamide metabolites (Ref. 166; Fig. bacterial gene cytosine deaminase in combination with the prodrug 3). Although tumor expression of antiapoptotic factors is widely 5-fluorocytosine (148, 149). Ganciclovir is ultimately activated to a considered to be associated with chemoresistance (31, 175), caspase cytotoxic nucleoside triphosphate, which induces caspase 8-mediated inhibitors such as p35 may nevertheless be useful for enhancing death in tumor cells that have a functional p53 (59) but proceeds via prodrug activation in the context of GDEPT treatments for cancer. a caspase 9 apoptotic pathway in p53-deficient cells (60). 5-Fluoro- The notion of introducing an antiapoptotic factor into a tumor cell cytosine is activated to 5-fluorouracil, an established anticancer drug may seem counterintuitive; however, caspase activity appears to be that activates the death receptor/caspase 8 pathway (53, 54), as noted nonessential for tumor cell death, as revealed by the ability of caspase above. pathway inhibitors to delay but, ultimately, not block tumor cell death A third enzyme-prodrug combination useful for GDEPT treatment (104, 176Ð178). This finding is intriguing and can be explained by the of cancer utilizes cytochrome P-450 enzymes, which can be combined observation that p35, IAP proteins, and certain other caspase inhibi- with a variety of anticancer prodrugs, the most widely studied one tors act downstream of the critical mitochondrial transition step; being the bifunctional alkylating agent cyclophosphamide and its consequently, these antiapoptotic factors do not interfere with the isomer ifosfamide (150, 151). P-450-based GDEPT has also been upstream release of cytochrome c that is mediated by Bax and other exemplified with certain bioreductive drugs (152, 153). This gene proapoptotic Bcl-2 family members in cells undergoing stress- or therapy appears to be particularly promising (154Ð159) and can be DNA damage-induced cell death (179). Once the mitochondrial apo- carried out using genes that code for endogenous human liver P-450 ptotic pathway has been engaged and mitochondrial potential is lost, enzymes, such as CYP2B6, diminishing the possibility of adverse drug-induced ATP depletion occurs, and a commitment to cell death immune responses (144). P-450-activated cyclophosphamide diffuses ensues, even in tumor cells that contain a strong caspase inhibitor, freely across cell membranes and elicits a substantial bystander cyto- such as p35 (166). The commitment to cell death in tumor cells that toxic effect, as shown in model studies using tumor cells grown in have undergone mitochondrial transition is manifested by the irrevers- monolayers (155) and spheroid cultures (157). The therapeutic poten- ible loss of clonogenic activity via a necrotic process (180Ð182). tial of P-450-based cancer GDEPT strategies has been exemplified Mitochondrial release of the proapoptotic factor AIF may contribute using retroviral and replicating herpes viral and adenoviral vectors to the irreversibility of drug-induced cell death in the presence of the (157, 160Ð162) and has shown promise in initial Phase I/Phase II caspase inhibitor p35, as indicated by the ability of AIF to induce trials with localized P-450 transfer using viral vectors or delivery of caspase-independent cell death (15, 183). AIF is sequestered in the microencapsulated P-450-expressing cells to the tumor vasculature mitochondrial intermembrane space, and following its release to (163Ð165). Further studies on the mechanisms of tumor cell death the cytosol in response to apoptotic stimulation, it translocates to the induced by P-450 prodrugs such as cyclophosphamide (51) may help nucleus and causes large-scale chromatin fragmentation (16). This identify tumor cell types that are most responsive to this therapeutic process is not blocked by the general caspase inhibitor benzyloxycar- strategy, as well as other chemotherapeutic agents and gene therapies bonal-Val-Ala-Asp-fluoromethylketone, although the release of AIF that provide synergy when combined with P-450 GDEPT. from mitochondria is regulated by Bcl-2 (14). 8567

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. APOPTOTIC FACTORS AND CANCER GENE THERAPY

Fig. 3. Enhanced suicide gene therapy by coex- pression of an antiapoptotic factor. In conventional suicide gene therapy (top panel), tumor cells trans- duced with a suicide gene serve as local factories that produce and release into the tumor microenvi- ronment active chemotherapeutic drug metabolite. However, the activated prodrug rapidly kills the prodrug-activating factory cell itself, limiting the cell’s ability to continue to generate active metab- olite and kill neighboring tumor cells by a by- stander mechanism. Delivery of a suicide gene in combination with an inhibitor of apoptosis, such as p35, prolongs factory cell death and enhances sui- cide gene therapy (bottom panel). The net forma- tion of cytotoxic drug metabolites is increased sub- stantially before the tumor factory cell eventually succumbs to drug-induced death.

The concept that underlies the introduction of a pan-caspase inhib- Although FLIPs have been associated with drug resistance (185, 186), itor to increase the bystander activity of P-450-activated cyclophos- the cell damage that is induced by chemotherapeutic drugs may itself phamide (166) is expected to be applicable to GDEPT using other be sufficient to kill the tumor cell, despite the inhibition of the caspase anticancer P-450 prodrugs, some 10Ð12 of which are known (144). 8-dependent apoptotic pathway. Factors that determine the extent to Other GDEPT enzyme-prodrug combinations, including those based which GDEPT activity can be enhanced using these approaches on the prodrugs ganciclovir and 5-fluorocytosine, are also likely to include the mechanism of cell death induced by the activated prodrug, benefit from strategies that delay death of prodrug-activating “factory the extent to which the antiapoptotic factor prolongs cell death, and cells” and thereby enhance bystander activity. The bystander activity the extent to which bystander killing is enhanced by expression of the of activated ganciclovir is relatively weak, and this contributes to the antiapoptotic factor. The ability of caspase inhibitors or other anti- limited effectiveness of HSV-tk-based gene therapies. However, even apoptotic factors to prolong but not block prodrug-induced cell death in the case of cytosine deaminase gene therapy using the prodrug may thus serve as a general way to enhance a broad range of suicide- 5-fluourocytosine, 5-fluouracil-producing tumor cells display up to a based cancer treatments. 500-fold greater susceptibility to killing than bystander tumor cells Finally, antiapoptotic factors may also be introduced into microen- (184), suggesting that the coexpression of p35 or other caspase inhib- capsulated cell vectors (187) to protect the encapsulated cell from the itors may increase bystander cytotoxic activity in this case as well. In cytotoxic action of a soluble proapoptotic factor that it produces. For p53-deficient tumor cells, HSV-tk GDEPT in combination with gan- example, FLIP or TRAIL decoy receptor could be introduced to ciclovir treatment activates the mitochondrial/caspase 9 pathway (60) protect cell vectors that have been engineered to secrete high levels of and should benefit from any increase in bystander activity that anti- TRAIL. In this way the encapsulated cells may secrete TRAIL into the apoptotic factors such as p35 may provide. tumor milieu for a prolonged period of time without themselves Several related approaches may be used to prolong tumor cell succumbing to TRAIL-induced apoptosis. survival and increase bystander activity in the case of GDEPT gene- prodrug combinations that activate the death receptor/caspase 8 path- Antiapoptotic Gene Therapies: Safety Considerations way, such as cytosine deaminase-5-fluorocytosine (53, 54). For ex- ample, overexpression of XIAP may provide for the selective To be effective, gene therapies that incorporate antiapoptotic fac- inhibition of effector caspases, leading to the desired delay in recep- tors must be carried out in a manner that avoids the induction of tumor tor-mediated cell death. XIAP does not block caspase 8 activation cell drug resistance. To achieve this goal, expression of the therapeu- (30), and consequently, the proapoptotic factor Bid may still undergo tic gene and the antiapoptotic factor should be tightly linked, e.g., by cleaving to tBid in XIAP-transduced cells, leading to mitochondrial use of an internal ribosome entry sequence (188), to preclude the transition and tumor cell death. tBid-induced mitochondrial transition possibility of expressing the antiapoptotic factor in tumor cells that do also leads to release of Smac/Diablo and negative feedback inhibition not also receive a drug sensitivity gene (e.g., the suicide/prodrug of XIAP, further facilitating death of the XIAP-expressing tumor activation gene). The immunogenicity of a nonmammalian antiapo- cells. In an alternative approach, death receptor pathway-mediated ptotic factor, such as the baculovirus protein p35, may further insure cell death may be prolonged without blocking the ultimate cytotoxic that all of the tumor cells that express the factor are ultimately outcome by overexpression of FLIPs, which are structurally similar to eliminated by the immune system. The introduction of an antiapo- caspase 8 and interfere with the recruitment and activation of caspase ptotic factor, such as p35, may shift the mechanism of drug-induced 8 by death receptors. The level of FLIP expression may be an cell death from an apoptotic pathway to necrotic cell death, potentially important determinant of its ability to slow down cell death but not leading to an enhanced systemic (immune system-based) bystander inhibit it. Decoy death receptors may also be used to slow transmis- killing effect. As an added measure of safety, the antiapoptotic factor sion of a death receptor signal without completely blocking it (34). can be placed under the control of a strong, repressible promoter, such 8568

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. APOPTOTIC FACTORS AND CANCER GENE THERAPY as the “Tet-off” expression system, so that it can be switched off when References necessary by treatment with the antibiotic tetracycline. Tet-off gene 1. Ding, H. F., and Fisher, D. E. Induction of apoptosis in cancer: new therapeutic therapy vectors provide a high degree of control of transgene expres- opportunities. Ann. Med., 34: 451Ð469, 2002. sion, which can be suppressed in a wide range of cells at doses of 2. Zornig, M., Hueber, A., Baum, W., and Evan, G. Apoptosis regulators and their role in tumorigenesis. Biochim. Biophys. Acta, 1551: F1ÐF37, 2001. tetracycline that are very low and exert no significant toxic effects on 3. Nunez, G., Benedict, M. A., Hu, Y., and Inohara, N. Caspases: the proteases of the cell proliferation or animal growth, even with continuous treatment apoptotic pathway. , 17: 3237Ð3245, 1998. (189Ð191). Safety could be further increased by building into the gene 4. Chen, M., and Wang, J. Initiator caspases in apoptosis signaling pathways. Apo- ptosis, 7: 313Ð319, 2002. therapy vector the inducible expression of a factor that kills the tumor 5. Thornberry, N. A., and Lazebnik, Y. Caspases: enemies within. Science (Wash. cell by an alternate pathway of cell death, one that is not blocked by DC), 281: 1312Ð1316, 1998. the antiapoptotic factor. For example, the pan-caspase inhibitor p35 6. Green, D. R. Apoptotic pathways: paper wraps stone blunts scissors. Cell, 102: 1Ð4, 2000. can be used to prolong the life of a P450-expressing prodrug factory 7. Sun, X. M., MacFarlane, M., Zhuang, J., Wolf, B. B., Green, D. R., and Cohen, cell, followed by the inducible expression of a death receptor ligand, G. M. Distinct caspase cascades are initiated in receptor-mediated and chemical- induced apoptosis. J. Biol. Chem., 274: 5053Ð5060, 1999. such as TRAIL, to eliminate any p35-expressing tumor cells that 8. Green, D. R. Apoptotic pathways: the roads to ruin. Cell, 94: 695Ð698, 1998. remain. Similarly, a TRAIL decoy receptor can be used to protect a 9. Ashkenazi, A., and Dixit, V. M. Death receptors: signaling and modulation. Science TRAIL-secreting tumor cell from TRAIL-induced suicide, followed (Wash. DC), 281: 1305Ð1308, 1998. 10. van Loo, G., Saelens, X., van Gurp, M., MacFarlane, M., Martin, S. J., and by inducible expression of a prodrug-activating enzyme and prodrug Vandenabeele, P. The role of mitochondrial factors in apoptosis: a Russian roulette treatment to insure elimination of the TRAIL decoy receptor-express- with more than one bullet. Cell Death Differ., 9: 1031Ð1042, 2002. ing cells. 11. Lemasters, J. J., Qian, T., He, L., Kim, J. S., Elmore, S. P., Cascio, W. E., and Brenner, D. A. Role of mitochondrial inner membrane permeabilization in necrotic Finally, antiapoptotic factors can be safely used in an alternative cell death, apoptosis, and . Antioxid. Redox Signal, 4: 769Ð781, 2002. gene-based therapy, whereby the therapeutic gene and the antiapo- 12. Green, D. R., and Reed, J. C. Mitochondria and apoptosis. Science (Wash. DC), 281: ptotic factor are incorporated into a cell-based vector, such as cellu- 1309Ð1312, 1998. 13. Slee, E. A., Harte, M. T., Kluck, R. M., Wolf, B. B., Casiano, C. A., Newmeyer, lose sulfate microencapsulated cells. Encapsulated cells have been D. D., Wang, H. G., Reed, J. C., Nicholson, D. W., Alnemri, E. S., Green, D. R., and used to deliver a prodrug-activating P-450 enzyme to the tumor Martin, S. J. Ordering the cytochrome c-initiated caspase cascade: hierarchical microenvironment (158, 165) and in an initial Phase I/Phase II trial activation of caspases-2, -3, -6, -7, -8, and -10 in a caspase-9-dependent manner. J. Cell Biol., 144: 281Ð292, 1999. showed promise for the treatment of advanced stage pancreatic tumors 14. Susin, S. A., Lorenzo, H. K., Zamzami, N., Marzo, I., Brenner, C., Larochette, N., (163Ð165). Introduction of an antiapoptotic factor, such as p35, may Prevost, M. C., Alzari, P. M., and Kroemer, G. Mitochondrial release of caspase-2 and -9 during the apoptotic process. J. Exp. Med., 189: 381Ð394, 1999. substantially prolong the viability and prodrug metabolic activity of 15. Joza, N., Susin, S. A., Daugas, E., Stanford, W. L., Cho, S. K., Li, C. Y., Sasaki, T., such an encapsulated cell vector. The cells used in this technology are Elia, A. J., Cheng, H. Y., Ravagnan, L., Ferri, K. F., Zamzami, N., Wakeham, A., modified by introduction of the therapeutic gene prior to encapsula- Hakem, R., Yoshida, H., Kong, Y. Y., Mak, T. W., Zuniga-Pflucker, J. C., Kroemer, G., and Penninger, J. M. Essential role of the mitochondrial apoptosis-inducing tion; direct gene therapeutic intervention in the target tumor cell is factor in programmed cell death. Nature (Lond.), 410: 549Ð554, 2001. therefore avoided, as is the possibility of introducing an antiapoptotic 16. Susin, S. A., Lorenzo, H. K., Zamzami, N., Marzo, I., Snow, B. E., Brothers, G. M., factor and tumor cell drug resistance. Mangion, J., Jacotot, E., Costantini, P., Loeffler, M., Larochette, N., Goodlett, D. R., Aebersold, R., Siderovski, D. P., Penninger, J. M., and Kroemer, G. Molecular characterization of mitochondrial apoptosis-inducing factor [see comments]. Nature Conclusion (Lond.), 397: 441Ð446, 1999. 17. Verhagen, A. M., Ekert, P. G., Pakusch, M., Silke, J., Connolly, L. M., Reid, G. E., Research carried out over the last decade has greatly expanded our Moritz, R. L., Simpson, R. J., and Vaux, D. L. Identification of DIABLO, a mammalian protein that promotes apoptosis by binding to and antagonizing IAP understanding of the multiple mechanisms and factors that control proteins. Cell, 102: 43Ð53, 2000. oncogenesis, regulate apoptosis, and contribute to tumor cell che- 18. Du, C., Fang, M., Li, Y., Li, L., and Wang, X. Smac, a mitochondrial protein that moresistance. Our growing understanding of the proapoptotic and promotes cytochrome c-dependent caspase activation by eliminating IAP inhibition. Cell, 102: 33Ð42, 2000. antiapoptotic responses that tumor cells undergo when challenged 19. Salvesen, G. S., and Duckett, C. S. IAP proteins: blocking the road to death’s door. with a chemotherapeutic drug may be applied to the design of novel Nat. Rev. Mol. Cell. Biol., 3: 401Ð410, 2002. gene therapeutic approaches for cancer treatment. The realization that 20. Chinnaiyan, A. M. The apoptosome: heart and soul of the cell death machine. Neoplasia, 1: 5Ð15, 1999. the effectiveness of GDEPT and related gene therapy strategies is 21. Cain, K., Bratton, S. B., and Cohen, G. M. The Apaf-1 apoptosome: a large critically dependent on optimizing the life span of the therapeutic caspase-activating complex. Biochimie, 84: 203Ð214, 2002. 22. Reed, J. C. Bcl-2 family proteins. Oncogene, 17: 3225Ð3236, 1998. gene-modified cell underpins several of these approaches. The finding 23. Baker, S. J., and Reddy, E. P. Modulation of life and death by the TNF receptor that coexpression of an anti-apoptotic factor with cytochrome P-450 superfamily. Oncogene, 17: 3261Ð3270, 1998. enhances P450 prodrug activation and bystander killing without in- 24. Micheau, O., Solary, E., Hammann, A., and Dimanche-Boitrel, M. T. Fas ligand- independent, FADD-mediated activation of the Fas death pathway by anticancer ducing drug resistance may serve as a model that can readily be drugs. J. Biol. Chem., 274: 7987Ð7992, 1999. adapted to other prodrug-activation GDEPT systems and other gene 25. Tibbetts, M. D., Zheng, L., and Lenardo, M. J. The death effector domain protein therapies. Additional mechanistic studies to elucidate the pathways of family: regulators of cellular homeostasis. Nat. Immunol., 4: 404Ð409, 2003. 26. Scaffidi, C., Fulda, S., Srinivasan, A., Friesen, C., Li, F., Tomaselli, K. J., Debatin, cell death activated by suicide gene therapies are likely to stimulate K. M., Krammer, P. H., and Peter, M. E. Two CD95 (APO-1/Fas) signaling further efforts toward the rational design of novel gene therapy pathways. EMBO J., 17: 1675Ð1687, 1998. combinations that maximize the production of soluble, bystander 27. Tang, D., Lahti, J. M., and Kidd, V. J. Caspase-8 activation and bid cleavage contribute to MCF7 cellular execution in a caspase-3-dependent manner during cytotoxic factors and prodrug metabolites while minimizing the po- staurosporine-mediated apoptosis. J. Biol. Chem., 275: 9303Ð9307, 2000. tential for development of drug-resistant tumor cell populations. A 28. Scaffidi, C., Schmitz, I., Zha, J., Korsmeyer, S. J., Krammer, P. H., and Peter, M. E. major hurdle to overcome when developing these therapies is the need Differential modulation of apoptosis sensitivity in CD95 type I and type II cells. J. Biol. Chem., 274: 22532Ð22538, 1999. for rigorous testing of treatments that incorporate antiapoptotic factors 29. Kuwana, T., Smith, J. J., Muzio, M., Dixit, V., Newmeyer, D. D., and Kornbluth, S. that may have tumorigenic potential. However, this requirement Apoptosis induction by caspase-8 is amplified through the mitochondrial release of cytochrome c. J. Biol. Chem., 273: 16589Ð16594, 1998. should be viewed in the context of the carcinogenic activity of many 30. Deveraux, Q. L., Roy, N., Stennicke, H. R., Van Arsdale, T., Zhou, Q., Srinivasula, current cancer chemotherapeutic drugs and balanced against the press- S. M., Alnemri, E. S., Salvesen, G. S., and Reed, J. C. IAPs block apoptotic events ing need to identify effective, tumor cell-selective therapies that have induced by caspase-8 and cytochrome c by direct inhibition of distinct caspases. EMBO J., 17: 2215Ð2223, 1998. acceptable systemic toxicities and provide durable therapeutic re- 31. Altieri, D. C. Validating survivin as a cancer therapeutic target. Nat. Rev. Cancer, 3: sponses. 46Ð54, 2003. 8569

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. APOPTOTIC FACTORS AND CANCER GENE THERAPY

32. Yang, Y., Fang, S., Jensen, J. P., Weissman, A. M., and Ashwell, J. D. Ubiquitin 60. Tomicic, M. T., Thust, R., and Kaina, B. Ganciclovir-induced apoptosis in HSV-1 protein ligase activity of IAPs and their degradation in in response to thymidine kinase expressing cells: critical role of DNA breaks, Bcl-2 decline and apoptotic stimuli. Science (Wash. DC), 288: 874Ð877, 2000. caspase-9 activation. Oncogene, 21: 2141Ð2153, 2002. 33. Ashkenazi, A., and Dixit, V. M. Apoptosis control by death and decoy receptors. 61. von Haefen, C., Wieder, T., Essmann, F., Schulze-Osthoff, K., Dorken, B., and Curr. Opin. Cell Biol., 11: 255Ð260, 1999. Daniel, P. T. Paclitaxel-induced apoptosis in BJAB cells proceeds via a death 34. Sheikh, M. S., and Fornace, A. J., Jr. Death and decoy receptors and p53-mediated receptor-independent, caspases-3/-8-driven mitochondrial amplification loop. Onco- apoptosis. (Baltimore), 14: 1509Ð1513, 2000. gene, 22: 2236Ð2247, 2003. 35. Pitti, R. M., Marsters, S. A., Lawrence, D. A., Roy, M., Kischkel, F. C., Dowd, P., 62. Huisman, C., Ferreira, C. G., Broker, L. E., Rodriguez, J. A., Smit, E. F., Postmus, Huang, A., Donahue, C. J., Sherwood, S. W., Baldwin, D. T., Godowski, P. J., P. E., Kruyt, F. A., and Giaccone, G. Paclitaxel triggers cell death primarily via Wood, W. I., Gurney, A. L., Hillan, K. J., Cohen, R. L., Goddard, A. D., Botstein, caspase-independent routes in the non-small cell cell line NCI-H460. D., and Ashkenazi, A. Genomic amplification of a decoy receptor for Fas ligand in Clin. Cancer Res., 8: 596Ð606, 2002. lung and colon cancer. Nature (Lond.), 396: 699Ð703, 1998. 63. Obrero, M., Yu, D. V., and Shapiro, D. J. Estrogen receptor-dependent and estrogen 36. Connolly, K., Cho, Y. H., Duan, R., Fikes, J., Gregorio, T., LaFleur, D. W., Okoye, receptor-independent pathways for tamoxifen and 4-hydroxytamoxifen-induced pro- Z., Salcedo, T. W., Santiago, G., Ullrich, S., Wei, P., Windle, K., Wong, E., Yao, grammed cell death. J. Biol. Chem., 277: 45695Ð45703, 2002. X. T., Zhang, Y. Q., Zheng, G., and Moore, P. A. In vivo inhibition of Fas 64. Van Den Bosch, M., Bree, R. T., and Lowndes, N. F. The MRN complex: coordi- ligand-mediated killing by TR6, a Fas ligand decoy receptor. J. Pharmacol. Exp. nating and mediating the response to broken chromosomes. EMBO Rep., 4: 844Ð Ther., 298: 25Ð33, 2001. 849, 2003. 37. van Noesel, M. M., van Bezouw, S., Salomons, G. S., Voute, P. A., Pieters, R., 65. Fei, P., and El-Deiry, W. S. p53 and radiation responses. Oncogene, 22: 5774Ð5783, Baylin, S. B., Herman, J. G., and Versteeg, R. Tumor-specific down-regulation of 2003. the tumor necrosis factor-related apoptosis-inducing ligand decoy receptors DcR1 66. Iliakis, G., Wang, Y., Guan, J., and Wang, H. DNA damage checkpoint control in and DcR2 is associated with dense promoter hypermethylation. Cancer Res., 62: cells exposed to ionizing radiation. Oncogene, 22: 5834Ð5847, 2003. 2157Ð2161, 2002. 67. Fukushima, T., Takata, M., Morrison, C., Araki, R., Fujimori, A., Abe, M., Tatsumi, 38. Zhang, X. D., Nguyen, T., Thomas, W. D., Sanders, J. E., and Hersey, P. Mecha- K., Jasin, M., Dhar, P. K., Sonoda, E., Chiba, T., and Takeda, S. Genetic analysis of nisms of resistance of normal cells to TRAIL induced apoptosis vary between the DNA-dependent protein kinase reveals an inhibitory role of Ku in late S-G2 different cell types. FEBS Lett., 482: 193Ð199, 2000. phase DNA double-strand break repair. J. Biol. Chem., 276: 44413Ð44418, 2001. 39. Bradley, J. R., and Pober, J. S. Tumor necrosis factor receptor-associated factors 68. Kharbanda, S., Yuan, Z. M., Weichselbaum, R., and Kufe, D. Determination of cell (TRAFs). Oncogene, 20: 6482Ð6491, 2001. fate by c-Abl activation in the response to DNA damage. Oncogene, 17: 3309Ð3318, ␣ 40. Gupta, S. A decision between life and death during TNF- -induced signaling. 1998. J. Clin. Immunol., 22: 185Ð194, 2002. 69. Yuan, L., Yu, W. M., Yuan, Z., Haudenschild, C. C., and Qu, C. K. Role of SHP-2 ␬ 41. Barkett, M., and Gilmore, T. Control of apoptosis by Rel/NF- B transcription tyrosine phosphatase in the DNA damage-induced cell death response. J. Biol. factors. Oncogene, 18: 6910Ð6924, 1999. Chem., 278: 15208Ð15216, 2003. 42. Wang, C. Y., Mayo, M. W., Korneluk, R. G., Goeddel, D. V., and Baldwin, A. S., ␬ 70. Meek, D. W. Mechanisms of switching on p53: a role for covalent modification? Jr. NF- B antiapoptosis: induction of TRAF1 and TRAF2 and c-IAP1 and c-IAP2 Oncogene, 18: 7666Ð7675, 1999. to suppress caspase-8 activation. Science (Wash. DC), 281: 1680Ð1683, 1998. 71. Gong, J. G., Costanzo, A., Yang, H. Q., Melino, G., Kaelin, W. G., Jr., Levrero, M., 43. Tang, G., Minemoto, Y., Dibling, B., Purcell, N. H., Li, Z., Karin, M., and Lin, A. ␬ and Wang, J. Y. The tyrosine kinase c-Abl regulates p73 in apoptotic response to Inhibition of JNK activation through NF- B target genes. Nature (Lond.), 414: cisplatin-induced DNA damage. Nature (Lond.), 399: 806Ð809, 1999. 313Ð317, 2001. 72. Agami, R., Blandino, G., Oren, M., and Shaul, Y. Interaction of c-Abl and p73␣ and 44. Bernard, D., Quatannens, B., Vandenbunder, B., and Abbadie, C. Rel/NF-␬B tran- their collaboration to induce apoptosis. Nature (Lond.), 399: 809Ð813, 1999. scription factors protect against tumor necrosis factor (TNF)-related apoptosis- 73. Lin, W. C., Lin, F. T., and Nevins, J. R. Selective induction of E2F1 in response to inducing ligand (TRAIL)-induced apoptosis by up-regulating the TRAIL decoy DNA damage, mediated by ATM-dependent phosphorylation. Genes Dev., 15: receptor DcR1. J. Biol. Chem., 276: 27322Ð27328, 2001. 1833Ð1844, 2001. 45. Micheau, O., Lens, S., Gaide, O., Alevizopoulos, K., and Tschopp, J. NF-␬B signals 74. Achanta, G., Pelicano, H., Feng, L., Plunkett, W., and Huang, P. Interaction of p53 induce the expression of c-FLIP. Mol. Cell. Biol., 21: 5299Ð5305, 2001. and DNA-PK in response to nucleoside analogues: potential role as a sensor 46. Wang, C. Y., Guttridge, D. C., Mayo, M. W., and Baldwin, A. S., Jr. NF-␬B induces complex for DNA damage. Cancer Res., 61: 8723Ð8729, 2001. expression of the Bcl-2 homologue A1/Bfl-1 to preferentially suppress chemother- 75. Gartel, A. L., and Tyner, A. L. The role of the cyclin-dependent kinase inhibitor p21 apy-induced apoptosis. Mol. Cell. Biol., 19: 5923Ð5929, 1999. in apoptosis. Mol. Cancer Ther., 1: 639Ð649, 2002. 47. Li, X., Yang, Y., and Ashwell, J. D. TNF-RII and c-IAP1 mediate ubiquitination and degradation of TRAF2. Nature (Lond.), 416: 345Ð347, 2002. 76. Rich, T., Allen, R. L., and Wyllie, A. H. Defying death after DNA damage. Nature 48. Sellers, W. R., and Fisher, D. E. Apoptosis and cancer drug targeting. J. Clin. (Lond.), 407: 777Ð783, 2000. Investig., 104: 1655Ð1661, 1999. 77. Oda, E., Ohki, R., Murasawa, H., Nemoto, J., Shibue, T., Yamashita, T., Tokino, T., 49. Papaconstantinou, H. T., Xie, C., Zhang, W., Ansari, N. H., Hellmich, M. R., Taniguchi, T., and Tanaka, N. Noxa, a BH3-only member of the Bcl-2 family and Townsend, C. M., Jr., and Ko, T. C. The role of caspases in methotrexate-induced candidate mediator of p53-induced apoptosis. Science (Wash. DC), 288: 1053Ð1058, gastrointestinal toxicity. Surgery, 130: 859Ð865, 2001. 2000. 50. Fulda, S., Susin, S. A., Kroemer, G., and Debatin, K. M. Molecular ordering of 78. Schuler, M., Maurer, U., Goldstein, J. C., Breitenbucher, F., Hoffarth, S., Water- apoptosis induced by anticancer drugs in cells. Cancer Res., 58: house, N. J., and Green, D. R. p53 triggers apoptosis in oncogene-expressing 4453Ð4460, 1998. fibroblasts by the induction of Noxa and mitochondrial Bax translocation. Cell 51. Schwartz, P. S., and Waxman, D. J. Cyclophosphamide induces caspase 9-dependent Death Differ., 10: 451Ð460, 2003. apoptosis in 9L tumor cells. Mol. Pharmacol., 60: 1268Ð1279, 2001. 79. Yu, J., Wang, Z., Kinzler, K. W., Vogelstein, B., and Zhang, L. PUMA mediates the 52. Kasibhatla, S., Brunner, T., Genestier, L., Echeverri, F., Mahboubi, A., and Green, apoptotic response to p53 in colorectal cancer cells. Proc. Natl. Acad. Sci. USA, D. R. DNA damaging agents induce expression of Fas ligand and subsequent 100: 1931Ð1936, 2003. apoptosis in T lymphocytes via the activation of NF-␬B and AP-1. Mol. Cell, 1: 80. Perego, P., Giarola, M., Righetti, S. C., Supino, R., Caserini, C., Delia, D., Pierotti, 543Ð551, 1998. M. A., Miyashita, T., Reed, J. C., and Zunino, F. Association between cisplatin 53. Tillman, D. M., Petak, I., and Houghton, J. A. A Fas-dependent component in resistance and mutation of p53 gene and reduced bax expression in ovarian carci- 5-fluorouracil/leucovorin-induced cytotoxicity in colon carcinoma cells. Clin. Can- noma cell systems. Cancer Res., 56: 556Ð562, 1996. cer Res., 5: 425Ð430, 1999. 81. Findley, H. W., Gu, L., Yeager, A. M., and Zhou, M. Expression and regulation of 54. Adachi, Y., Taketani, S., Oyaizu, H., Ikebukuro, K., Tokunaga, R., and Ikehara, S. Bcl-2, Bcl-xl, and Bax correlate with p53 status and sensitivity to apoptosis in Apoptosis of colorectal adenocarcinoma induced by 5-FU and/or IFN-gamma childhood acute lymphoblastic leukemia. Blood, 89: 2986Ð2993, 1997. through caspase 3 and caspase 8. Int. J. Oncol., 15: 1191Ð1196, 1999. 82. Donald, S. P., Sun, X. Y., Hu, C. A., Yu, J., Mei, J. M., Valle, D., and Phang, J. M. 55. Stahnke, K., Fulda, S., Friesen, C., Strauss, G., and Debatin, K. M. Activation of Proline oxidase, encoded by p53-induced gene-6, catalyzes the generation of apoptosis pathways in peripheral blood lymphocytes by in vivo chemotherapy. proline-dependent . Cancer Res., 61: 1810Ð1815, 2001. Blood, 98: 3066Ð3073, 2001. 83. Maxwell, S. A., and Rivera, A. Proline oxidase induces apoptosis in tumor cells, and 56. Seki, K., Yoshikawa, H., Shiiki, K., Hamada, Y., Akamatsu, N., and Tasaka, K. its expression is frequently absent or reduced in renal carcinomas. J. Biol. Chem., Cisplatin (CDDP) specifically induces apoptosis via sequential activation of 278: 9784Ð9789, 2003. caspase-8, -3 and -6 in . Cancer Chemother. Pharmacol., 45: 199Ð206, 84. Hollstein, M., Sidransky, D., Vogelstein, B., and Harris, C. C. p53 mutations in 2000. human . Science (Wash. DC), 253: 49Ð53, 1991. 57. Ofir, R., Seidman, R., Rabinski, T., Krup, M., Yavelsky, V., Weinstein, Y., and 85. Raina, D., Mishra, N., Kumar, S., Kharbanda, S., Saxena, S., and Kufe, D. Inhibition Wolfson, M. Taxol-induced apoptosis in human SKOV3 ovarian and MCF7 breast of c-Abl with STI571 attenuates stress-activated protein kinase activation and apo- carcinoma cells is caspase-3 and caspase-9 independent. Cell Death Differ., 9: ptosis in the cellular response to 1-␤-D-arabinofuranosylcytosine. Mol. Pharmacol., 636Ð642, 2002. 61: 1489Ð1495, 2002. 58. Yuan, S. Y., Hsu, S. L., Tsai, K. J., and Yang, C. R. Involvement of mitochondrial 86. Blattner, C., Sparks, A., and Lane, D. Transcription factor E2F-1 is upregulated in pathway in Taxol-induced apoptosis of human T24 cells. Urol. Res., response to DNA damage in a manner analogous to that of p53. Mol. Cell. Biol., 19: 30: 282Ð288, 2002. 3704Ð3713, 1999. 59. Beltinger, C., Fulda, S., Kammertoens, T., Meyer, E., Uckert, W., and Debatin, 87. Pediconi, N., Ianari, A., Costanzo, A., Belloni, L., Gallo, R., Cimino, L., Porcellini, K. M. Herpes simplex virus thymidine kinase/ganciclovir-induced apoptosis in- A., Screpanti, I., Balsano, C., Alesse, E., Gulino, A., and Levrero, M. Differential volves ligand-independent death receptor aggregation and activation of caspases. regulation of E2F1 apoptotic target genes in response to DNA damage. Nat. Cell Proc. Natl. Acad. Sci. USA, 96: 8699Ð8704, 1999. Biol., 5: 552Ð558, 2003. 8570

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. APOPTOTIC FACTORS AND CANCER GENE THERAPY

88. Moroni, M. C., Hickman, E. S., Denchi, E. L., Caprara, G., Colli, E., Cecconi, F., 118. Kagawa, S., Gu, J., Swisher, S. G., Ji, L., Roth, J. A., Lai, D., Stephens, L. C., and Muller, H., and Helin, K. Apaf-1 is a transcriptional target for E2F and p53. Nat. Fang, B. Antitumor effect of adenovirus-mediated Bax gene transfer on p53- Cell Biol., 3: 552Ð558, 2001. sensitive and p53-resistant cancer lines. Cancer Res., 60: 1157Ð1161, 2000. 89. Furukawa, Y., Nishimura, N., Satoh, M., Endo, H., Iwase, S., Yamada, H., Matsuda, 119. Kaliberov, S. A., Buchsbaum, D. J., Gillespie, G. Y., Curiel, D. T., Arafat, W. O., M., Kano, Y., and Nakamura, M. Apaf-1 is a mediator of E2F-1-induced apoptosis. Carpenter, M., and Stackhouse, M. A. Adenovirus-mediated transfer of BAX driven J. Biol. Chem., 277: 39760Ð39768, 2002. by the vascular endothelial growth factor promoter induces apoptosis in lung cancer 90. Nahle, Z., Polakoff, J., Davuluri, R. V., McCurrach, M. E., Jacobson, M. D., Narita, cells. Mol. Ther., 6: 190Ð198, 2002. M., Zhang, M. Q., Lazebnik, Y., Bar-Sagi, D., and Lowe, S. W. Direct coupling of 120. Waters, J. S., Webb, A., Cunningham, D., Clarke, P. A., Raynaud, F., di Stefano, F., the cell cycle and cell death machinery by E2F. Nat. Cell Biol., 4: 859Ð864, 2002. and Cotter, F. E. Phase I clinical and pharmacokinetic study of bcl-2 antisense 91. Croxton, R., Ma, Y., Song, L., Haura, E. B., and Cress, W. D. Direct repression of oligonucleotide therapy in patients with non-Hodgkin’s lymphoma. J. Clin. Oncol., the Mcl-1 promoter by E2F1. Oncogene, 21: 1359Ð1369, 2002. 18: 1812Ð1823, 2000. 92. Wang, J. Y., and Ki, S. W. Choosing between growth arrest and apoptosis through 121. Klasa, R. J., Bally, M. B., Ng, R., Goldie, J. H., Gascoyne, R. D., and Wong, F. M. the retinoblastoma tumour suppressor protein, Abl and p73. Biochem. Soc. Trans., Eradication of human non-Hodgkin’s lymphoma in SCID mice by BCL-2 antisense 29: 666Ð673, 2001. oligonucleotides combined with low-dose cyclophosphamide. Clin. Cancer Res., 6: 93. Irwin, M. S., Kondo, K., Marin, M. C., Cheng, L. S., Hahn, W. C., and Kaelin, W. G. 2492Ð2500, 2000. Chemosensitivity linked to p73 function. Cancer Cell, 3: 403Ð410, 2003. 122. Zangemeister-Wittke, U., Leech, S. H., Olie, R. A., Simoes-Wust, A. P., Gautschi, 94. Ben-Yehoyada, M., Ben-Dor, I., and Shaul, Y. c-Abl tyrosine kinase selectively O., Luedke, G. H., Natt, F., Haner, R., Martin, P., Hall, J., Nalin, C. M., and Stahel, regulates p73 nuclear matrix association. J. Biol. Chem., 278: 34475Ð34482, 2003. R. A. A novel bispecific antisense oligonucleotide inhibiting both bcl-2 and bcl-xL 95. Costanzo, A., Merlo, P., Pediconi, N., Fulco, M., Sartorelli, V., Cole, P. A., expression efficiently induces apoptosis in tumor cells. Clin. Cancer Res., 6: Fontemaggi, G., Fanciulli, M., Schiltz, L., Blandino, G., Balsano, C., and Levrero, 2547Ð2555, 2000. M. DNA damage-dependent acetylation of p73 dictates the selective activation of 123. Piche, A., Grim, J., Rancourt, C., Gomez-Navarro, J., Reed, J. C., and Curiel, D. T. apoptotic target genes. Mol. Cell., 9: 175Ð186, 2002. Modulation of Bcl-2 protein levels by an intracellular anti-Bcl-2 single-chain anti- 96. Tsai, K. K., and Yuan, Z. M. c-Abl stabilizes p73 by a phosphorylation-augmented body increases drug-induced cytotoxicity in the cell line MCF-7. interaction. Cancer Res., 63: 3418Ð3424, 2003. Cancer Res., 58: 2134Ð2140, 1998. 97. Muller, M., Strand, S., Hug, H., Heinemann, E. M., Walczak, H., Hofmann, W. J., 124. Jiang, M., and Milner, J. Bcl-2 constitutively suppresses p53-dependent apoptosis in Stremmel, W., Krammer, P. H., and Galle, P. R. Drug-induced apoptosis in hepa- colorectal cancer cells. Genes Dev., 17: 832Ð837, 2003. toma cells is mediated by the CD95 (APO-1/Fas) receptor/ligand system and 125. Tzung, S. P., Kim, K. M., Basanez, G., Giedt, C. D., Simon, J., Zimmerberg, J., involves activation of wild-type p53. J. Clin. Investig., 99: 403Ð413, 1997. Zhang, K. Y., and Hockenbery, D. M. Antimycin A mimics a cell-death-inducing 98. Friesen, C., Herr, I., Krammer, P. H., and Debatin, K. M. Involvement of the CD95 Bcl-2 homology domain 3. Nat. Cell Biol., 3: 183Ð191, 2001. (APO-1/FAS) receptor/ligand system in drug-induced apoptosis in leukemia cells. 126. Degterev, A., Lugovskoy, A., Cardone, M., Mulley, B., Wagner, G., Mitchison, T., Nat. Med., 2: 574Ð577, 1996. and Yuan, J. Identification of small-molecule inhibitors of interaction between the 99. Wu, G. S., Burns, T. F., McDonald, E. R., III, Meng, R. D., Kao, G., Muschel, R., BH3 domain and Bcl-xL. Nat. Cell Biol., 3: 173Ð182, 2001. Yen, T., and el-Deiry, W. S. Induction of the TRAIL receptor KILLER/DR5 in 127. Ashkenazi, A., Pai, R. C., Fong, S., Leung, S., Lawrence, D. A., Marsters, S. A., p53-dependent apoptosis but not growth arrest. Oncogene, 18: 6411Ð6418, 1999. Blackie, C., Chang, L., McMurtrey, A. E., Hebert, A., DeForge, L., Koumenis, I. L., 100. Nagane, M., Pan, G., Weddle, J. J., Dixit, V. M., Cavenee, W. K., and Huang, H. J. Lewis, D., Harris, L., Bussiere, J., Koeppen, H., Shahrokh, Z., and Schwall, R. H. Increased death receptor 5 expression by chemotherapeutic agents in human gliomas Safety and antitumor activity of recombinant soluble Apo2 ligand. J. Clin. Investig., causes synergistic cytotoxicity with tumor necrosis factor-related apoptosis-inducing 104: 155Ð162, 1999. 128. Kagawa, S., He, C., Gu, J., Koch, P., Rha, S. J., Roth, J. A., Curley, S. A., Stephens, ligand and in vivo. Cancer Res., 60: 847Ð853, 2000. L. C., and Fang, B. Antitumor activity and bystander effects of the tumor necrosis 101. Eichhorst, S. T., Muller, M., Li-Weber, M., Schulze-Bergkamen, H., Angel, P., and factor-related apoptosis-inducing ligand (TRAIL) gene. Cancer Res., 61: 3330Ð Krammer, P. H. A novel AP-1 element in the CD95 ligand promoter is required for 3338, 2001. induction of apoptosis in hepatocellular carcinoma cells upon treatment with anti- 129. Keane, M. M., Ettenberg, S. A., Nau, M. M., Russell, E. K., and Lipkowitz, S. cancer drugs. Mol. Cell. Biol., 20: 7826Ð7837, 2000. Chemotherapy augments TRAIL-induced apoptosis in breast cell lines. Cancer Res., 102. Mow, B. M., Blajeski, A. L., Chandra, J., and Kaufmann, S. H. Apoptosis and the 59: 734Ð741, 1999. response to anticancer therapy. Curr. Opin. Oncol., 13: 453Ð462, 2001. 130. Cuello, M., Ettenberg, S. A., Nau, M. M., and Lipkowitz, S. Synergistic induction 103. Petak, I., and Houghton, J. A. Shared pathways: death receptors and cytotoxic drugs of apoptosis by the combination of trail and chemotherapy in chemoresistant ovarian in cancer therapy. Pathol. Oncol. Res., 7: 95Ð106, 2001. cancer cells. Gynecol. Oncol., 81: 380Ð390, 2001. 104. Petak, I., Tillman, D. M., Harwood, F. G., Mihalik, R., and Houghton, J. A. 131. Daniel, P. T., Wieder, T., Sturm, I., and Schulze-Osthoff, K. The kiss of death: Fas-dependent and -independent mechanisms of cell death following DNA damage promises and failures of death receptors and ligands in cancer therapy. Leukemia in human colon carcinoma cells. Cancer Res., 60: 2643Ð2650, 2000. (Baltimore), 15: 1022Ð1032, 2001. 105. Kinoshita, H., Yoshikawa, H., Shiiki, K., Hamada, Y., Nakajima, Y., and Tasaka, K. 132. Huang, X., Lin, T., Gu, J., Zhang, L., Roth, J. A., Stephens, L. C., Yu, Y., Liu, J., Cisplatin (CDDP) sensitizes human osteosarcoma cell to Fas/CD95-mediated apo- and Fang, B. Combined TRAIL and Bax gene therapy prolonged survival in mice ptosis by down-regulating FLIP-L expression. Int. J. Cancer, 88: 986Ð991, 2000. with xenograft. Gene Ther., 9: 1379Ð1386, 2002. 106. Swisher, S. G., and Roth, J. A. Clinical update of Ad-p53 gene therapy for lung 133. Kim, K., Takimoto, R., Dicker, D. T., Chen, Y., Gazitt, Y., and El-Deiry, W. S. cancer. Surg. Oncol. Clin. N. Am., 11: 521Ð535, 2002. Enhanced TRAIL sensitivity by p53 overexpression in human cancer but not normal 107. Reed, J. C. Apoptosis-based therapies. Nat. Rev. Drug Discov., 11: 111Ð121, 2002. cell lines. Int. J. Oncol., 18: 241Ð247, 2001. 108. Lane, D. P., and Lain, S. Therapeutic exploitation of the p53 pathway. Trends Mol. 134. Fulda, S., Wick, W., Weller, M., and Debatin, K. M. Smac agonists sensitize for Med., 8: S38ÐS42, 2002. Apo2L/TRAIL- or anticancer drug-induced apoptosis and induce regression of 109. Fueyo, J., Gomez-Manzano, C., Yung, W. K., Liu, T. J., Alemany, R., McDonnell, malignant glioma in vivo. Nat. Med., 8: 808Ð815, 2002. T. J., Shi, X., Rao, J. S., Levin, V. A., and Kyritsis, A. P. Overexpression of E2F-1 135. Ng, C. P., and Bonavida, B. X-linked inhibitor of apoptosis (XIAP) blocks Apo2 in glioma triggers apoptosis and suppresses tumor growth in vitro and in vivo. Nat. ligand/tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis Med., 4: 685Ð690, 1998. of prostate cancer cells in the presence of mitochondrial activation: sensitization by 110. Dong, Y. B., Yang, H. L., Elliott, M. J., and McMasters, K. M. Adenovirus-mediated overexpression of second mitochondria-derived activator of caspase/direct IAP- E2F-1 gene transfer sensitizes cells to apoptosis induced by topoisomer- binding protein with low pl (Smac/DIABLO). Mol. Cancer Ther., 1: 1051Ð1058, ase II inhibitors. Cancer Res., 62: 1776Ð1783, 2002. 2002. 111. Kim, R., Tanabe, K., Emi, M., Uchida, Y., Inoue, H., and Toge, T. Inducing cancer 136. Guo, F., Nimmanapalli, R., Paranawithana, S., Wittman, S., Griffin, D., Bali, P., cell death by targeting transcription factors. Anticancer Drugs, 14: 3Ð11, 2003. O’Bryan, E., Fumero, C., Wang, H. G., and Bhalla, K. Ectopic overexpression of 112. Deng, J., Xia, W., and Hung, M. C. Adenovirus 5 E1A-mediated tumor suppression second mitochondria-derived activator of caspases (Smac/DIABLO) or cotreatment associated with E1A-mediated apoptosis in vivo. Oncogene, 17: 2167Ð2175, 1998. with N-terminus of Smac/DIABLO peptide potentiates epothilone B derivative- 113. Nettelbeck, D. M., Rivera, A. A., Balague, C., Alemany, R., and Curiel, D. T. Novel (BMS 247550) and Apo-2L/TRAIL-induced apoptosis. Blood, 99: 3419Ð3426, oncolytic adenoviruses targeted to melanoma: specific viral replication and cytolysis 2002. by expression of E1A mutants from the tyrosinase enhancer/promoter. Cancer Res., 137. Weaver, K. D., Yeyeodu, S., Cusack, J. C., Jr., Baldwin, A. S., Jr., and Ewend, M. G. 62: 4663Ð4670, 2002. Potentiation of chemotherapeutic agents following antagonism of nuclear factor-␬B 114. Yamabe, K., Shimizu, S., Ito, T., Yoshioka, Y., Nomura, M., Narita, M., Saito, I., in human gliomas. J. Neurooncol., 61: 187Ð196, 2003. Kanegae, Y., and Matsuda, H. Cancer gene therapy using a pro-apoptotic gene, 138. Chen, S., Fribley, A., and Wang, C. Y. Potentiation of tumor necrosis factor- caspase-3. Gene Ther., 6: 1952Ð1959, 1999. mediated apoptosis of oral squamous cell carcinoma cells by adenovirus-mediated 115. Marcelli, M., Cunningham, G. R., Walkup, M., He, Z., Sturgis, L., Kagan, C., gene transfer of NF-␬B inhibitor. J. Dent. Res., 81: 98Ð102, 2002. Mannucci, R., Nicoletti, I., Teng, B., and Denner, L. Signaling pathway activated 139. Tietze, M. K., Wuestefeld, T., Paul, Y., Zender, L., Trautwein, C., Manns, M. P., and during apoptosis of the prostate cancer cell line LNCaP: overexpression of caspase-7 Kubicka, S. I␬B␣ gene therapy in tumor necrosis factor-␣- and chemotherapy- as a new gene therapy strategy for prostate cancer. Cancer Res., 59: 382Ð390, 1999. mediated apoptosis of hepatocellular carcinomas. Cancer Gene Ther., 7: 1315Ð1323, 116. Mesri, M., Wall, N. R., Li, J., Kim, R. W., and Altieri, D. C. Cancer gene therapy 2000. using a survivin mutant adenovirus. J. Clin. Investig., 108: 981Ð990, 2001. 140. Adams, J. Potential for proteasome inhibition in the treatment of cancer. Drug 117. Perkins, C. L., Fang, G., Kim, C. N., and Bhalla, K. N. The role of Apaf-1, Discov. Today, 8: 307Ð315, 2003. caspase-9, and bid proteins in etoposide- or paclitaxel-induced mitochondrial events 141. Cheson, B. D. Hematologic malignancies: new developments and future treatments. during apoptosis. Cancer Res., 60: 1645Ð1653, 2000. Semin. Oncol., 29: 33Ð45, 2002. 8571

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. APOPTOTIC FACTORS AND CANCER GENE THERAPY

142. Biswas, D. K., Martin, K. J., McAlister, C., Cruz, A. P., Graner, E., Dai, S. C., and ifosfamide at the site of the tumor: the magic bullets of the 21st century. Cancer Pardee, A. B. Apoptosis caused by chemotherapeutic inhibition of nuclear factor-␬B Chemother. Pharmacol., 49 Suppl 1: S21ÐS24, 2002. activation. Cancer Res., 63: 290Ð295, 2003. 166. Schwartz, P. S., Chen, C. S., and Waxman, D. J. Enhanced bystander cytotoxicity of 143. Springer, C. J., and Niculescu-Duvaz, I. Prodrug-activating systems in suicide gene P450 gene-directed enzyme prodrug therapy by expression of the antiapoptotic therapy. J. Clin. Investig., 105: 1161Ð1167, 2000. factor p35. Cancer Res., 62: 6928Ð6937, 2002. 144. Chen, L., and Waxman, D., J. Cytochrome P450 gene-directed enzyme prodrug 167. Gamcsik, M. P., Dolan, M. E., Andersson, B. S., and Murray, D. Mechanisms of therapy (GDEPT) for cancer. Curr. Pharmaceut. Design, 8: 1405Ð1416, 2002. resistance to the toxicity of cyclophosphamide. Curr. Pharmaceut. Design, 5: 587Ð 145. Pope, I. M., Poston, G. J., and Kinsella, A. R. The role of the bystander effect in 605, 1999. suicide gene therapy. Eur. J. Cancer, 33: 1005Ð1016, 1997. 168. Chen, G., and Waxman, D. J. Role of cellular glutathione and glutathione S- 146. Sturtz, F. G., Waddell, K., Shulok, J., Chen, X., Caruso, M., Sanson, M., Snodgrass, transferase in the expression of alkylating agent cytotoxicity in human breast cancer H. R., and Platika, D. Variable efficiency of the thymidine kinase/ganciclovir system cells. Biochem. Pharmacol., 47: 1079Ð1087, 1994. in human glioblastoma cell lines: implications for gene therapy. Hum. Gene Ther., 169. Waxman, D. J. Glutathione S-transferases: role in alkylating agent resistance and 8: 1945Ð1953, 1997. possible target for modulation chemotherapy: a review. Cancer Res., 50: 6449Ð 147. Moolten, F. L., and Wells, J. M. Curability of tumors bearing herpes thymidine 6454, 1990. kinase genes transferred by retroviral vectors. J. Natl. Cancer Inst., 82: 297Ð300, 170. Sladek, N. E. Aldehyde dehydrogenase-mediated cellular relative insensitivity to the 1990. oxazaphosphorines. Curr. Pharmaceut. Design, 5: 607Ð625, 1999. 148. Mullen, C. A., Coale, M. M., Lowe, R., and Blaese, R. M. Tumors expressing the 171. Chen, G., and Waxman, D. J. Identification of glutathione S-transferase as a cytosine deaminase suicide gene can be eliminated in vivo with 5-fluorocytosine and determinant of 4-hydroperoxycyclophosphamide resistance in human breast cancer induce protective immunity to wild-type tumor. Cancer Res., 54: 1503Ð1506, 1994. cells. Biochem. Pharmacol., 49: 1691Ð1701, 1995. 149. Huber, B. E., Austin, E. A., Good, S. S., Knick, V. C., Tibbels, S., and Richards, 172. Yang, W. Z., Begleiter, A., Johnston, J. B., Israels, L. G., and Mowat, M. R. Role C. A. In vivo antitumor activity of 5-fluorocytosine on human colorectal carcinoma of glutathione and glutathione S-transferase in chlorambucil resistance. Mol. Phar- cells genetically modified to express cytosine deaminase. Cancer Res., 53: 4619Ð macol., 41: 625Ð630, 1992. 4626, 1993. 173. Puchalski, R. B., and Fahl, W. E. Expression of recombinant glutathione S-trans- 150. Wei, M. X., Tamiya, T., Chase, M., Boviatsis, E. J., Chang, T. K. H., Kowall, N. W., ferase pi, Ya, or Yb1 confers resistance to alkylating agents. Proc. Natl. Acad. Sci. Hochberg, F. H., Waxman, D. J., Breakefield, X. O., and Chiocca, E. A. Experi- USA, 87: 2443Ð2447, 1990. mental tumor therapy in mice using the cyclophosphamide-activating cytochrome 174. Clem, R. J., and Miller, L. K. Control of programmed cell death by the baculovirus P450 2B1 gene. Hum. Gene Ther., 5: 969Ð978, 1994. genes p35 and iap. Mol. Cell. Biol., 14: 5212Ð5222, 1994. 151. Chen, L., and Waxman, D. J. Intratumoral activation and enhanced chemotherapeu- 175. Hersey, P., and Zhang, X. D. Overcoming resistance of cancer cells to apoptosis. tic effect of oxazaphosphorines following cytochrome P-450 gene transfer: devel- J. Cell Physiol., 196: 9Ð18, 2003. opment of a combined chemotherapy/cancer gene therapy strategy. Cancer Res., 55: 176. Lock, R. B., and Stribinskiene, L. Dual modes of death induced by etoposide in 581Ð589, 1995. human epithelial tumor cells allow Bcl-2 to inhibit apoptosis without affecting 152. Jounaidi, Y., and Waxman, D. J. Combination of the bioreductive drug tirapazamine clonogenic survival. Cancer Res., 56: 4006Ð4012, 1996. with the chemotherapeutic prodrug cyclophosphamide for P450/P450-reductase- 177. Yin, D. X., and Schimke, R. T. Bcl-2 expression delays drug-induced apoptosis but based cancer gene therapy. Cancer Res., 60: 3761Ð3769, 2000. does not increase clonogenic survival after drug treatment in HeLa cells. Cancer 153. McCarthy, H. O., Yakkundi, A., McErlane, V., Hughes, C. M., Keilty, G., Murray, Res., 55: 4922Ð4928, 1995. M., Patterson, L. H., Hirst, D. G., McKeown, S. R., and Robson, T. Bioreductive 178. Breton, C., Story, M. D., and Meyn, R. E. Bcl-2 expression correlates with apoptosis GDEPT using cytochrome P450 3A4 in combination with AQ4N. Cancer Gene induction but not loss of clonogenic survival in small cell lung cancer cell lines Ther., 10: 40Ð48, 2003. treated with etoposide. Anticancer Drugs, 9: 751Ð757, 1998. 154. Chen, L., Waxman, D. J., Chen, D., and Kufe, D. W. Sensitization of human breast 179. Roy, N., Deveraux, Q. L., Takahashi, R., Salvesen, G. S., and Reed, J. C. The cancer cells to cyclophosphamide and ifosfamide by transfer of a liver cytochrome c-IAP-1 and c-IAP-2 proteins are direct inhibitors of specific caspases. EMBO J., P450 gene. Cancer Res., 56: 1331Ð1340, 1996. 16: 6914Ð6925, 1997. 155. Jounaidi, Y., Hecht, J. E., and Waxman, D. J. Retroviral transfer of human cyto- 180. Xue, L., Fletcher, G. C., and Tolkovsky, A. M. Mitochondria are selectively chrome P450 genes for oxazaphosphorine-based cancer gene therapy. Cancer Res., eliminated from eukaryotic cells after blockade of caspases during apoptosis. Curr. 58: 4391Ð4401, 1998. Biol., 11: 361Ð365, 2001. 156. Jounaidi, Y., and Waxman, D. J. Frequent, moderate dose cyclophosphamide ad- ministration improves the efficacy of P450/P450 reductase-based cancer gene ther- 181. Amarante-Mendes, G. P., Finucane, D. M., Martin, S. J., Cotter, T. G., Salvesen, apy. Cancer Res., 61: 4437Ð4444, 2001. G. S., and Green, D. R. Anti-apoptotic prevent caspase-dependent and 157. Kan, O., Griffiths, L., Baban, D., Iqball, S., Uden, M., Spearman, H., Slingsby, J., independent commitment for cell death. Cell Death Differ., 5: 298Ð306, 1998. Price, T., Esapa, M., Kingsman, S., Kingsman, A., Slade, A., and Naylor, S. Direct 182. Brunet, C. L., Gunby, R. H., Benson, R. S., Hickman, J. A., Watson, A. J., and retroviral delivery of human cytochrome P450 2B6 for gene-directed enzyme Brady, G. Commitment to cell death measured by loss of clonogenicity is separable prodrug therapy of cancer. Cancer Gene Ther., 8: 473Ð482, 2001. from the appearance of apoptotic markers. Cell Death Differ., 5: 107Ð115, 1998. 158. Muller, P., Jesnowski, R., Karle, P., Renz, R., Saller, R., Stein, H., Puschel, K., von 183. Joseph, B., Marchetti, P., Formstecher, P., Kroemer, G., Lewensohn, R., and Rombs, K., Nizze, H., Liebe, S., Wagner, T., Gunzburg, W. H., Salmons, B., and Zhivotovsky, B. Mitochondrial dysfunction is an essential step for killing of non- Lohr, M. Injection of encapsulated cells producing an ifosfamide-activating cyto- small cell lung carcinomas resistant to conventional treatment. Oncogene, 21: chrome P450 for targeted chemotherapy to pancreatic tumors. Ann. NY Acad. Sci., 65Ð77, 2002. 880: 337Ð351, 1999. 184. Lawrence, T. S., Rehemtulla, A., Ng, E. Y., Wilson, M., Trosko, J. E., and Stetson, 159. Ichikawa, T., Petros, W. P., Ludeman, S. M., Fangmeier, J., Hochberg, F. H., Colvin, P. L. Preferential cytotoxicity of cells transduced with cytosine deaminase compared O. M., and Chiocca, E. A. Intraneoplastic polymer-based delivery of cyclophos- to bystander cells after treatment with 5-flucytosine. Cancer Res., 58: 2588Ð2593, phamide for intratumoral bioconversion by a replicating oncolytic viral vector. 1998. Cancer Res., 61: 864Ð868, 2001. 185. Bortul, R., Tazzari, P. L., Cappellini, A., Tabellini, G., Billi, A. M., Bareggi, R., 160. Pawlik, T. M., Nakamura, H., Mullen, J. T., Kasuya, H., Yoon, S. S., Chandrasekhar, Manzoli, L., Cocco, L., and Martelli, A. M. Constitutively active Akt1 protects S., Chiocca, E. A., and Tanabe, K. K. Prodrug bioactivation and oncolysis of diffuse HL60 leukemia cells from TRAIL-induced apoptosis through a mechanism involv- liver metastases by a herpes simplex virus 1 mutant that expresses the CYP2B1 ing NF-␬B activation and cFLIP(L) up-regulation. Leukemia (Baltimore), 17: 379Ð transgene. Cancer (Phila.), 95: 1171Ð1181, 2002. 389, 2003. 161. Aghi, M., Chou, T. C., Suling, K., Breakefield, X. O., and Chiocca, E. A. Multi- 186. Xiao, C. W., Yan, X., Li, Y., Reddy, S. A., and Tsang, B. K. Resistance of human modal cancer treatment mediated by a replicating oncolytic virus that delivers the ovarian cancer cells to tumor necrosis factor ␣ is a consequence of nuclear factor- oxazaphosphorine/rat cytochrome P450 2B1 and ganciclovir/herpes simplex virus ␬B-mediated induction of Fas-associated death domain-like interleukin-1␤-convert- thymidine kinase gene therapies. Cancer Res., 59: 3861Ð3865, 1999. ing enzyme-like inhibitory protein. Endocrinology, 144: 623Ð630, 2003. 162. Jounaidi, Y., and Waxman, D. J. Use of replication-conditional adenovirus as a 187. Visted, T., Bjerkvig, R., and Enger, P. O. Cell encapsulation technology as a helper system for enhanced delivery of P450 prodrug-activation genes for cancer therapeutic strategy for CNS malignancies. Neurooncol., 3: 201Ð210, 2001. therapy. Cancer Res., 64: January, in press, 2004. 188. de Felipe, P. Polycistronic viral vectors. Curr. Gene Ther., 2: 355Ð378, 2002. 163. Kan, O., Kingsman, S., and Naylor, S. Cytochrome P450-based cancer gene therapy: 189. Mizuguchi, H., and Hayakawa, T. The tet-off system is more effective than the current status. Expert Opin. Biol. Ther., 2: 857Ð868, 2002. tet-on system for regulating transgene expression in a single adenovirus vector. 164. Lohr, M., Hoffmeyer, A., Kroger, J., Freund, M., Hain, J., Holle, A., Karle, P., J. Gene Med., 4: 240Ð247, 2002. Knofel, W. T., Liebe, S., Muller, P., Nizze, H., Renner, M., Saller, R. M., Wagner, 190. Mayford, M., Bach, M. E., Huang, Y. Y., Wang, L., Hawkins, R. D., and Kandel, T., Hauenstein, K., Gunzburg, W. H., and Salmons, B. Microencapsulated cell- E. R. Control of memory formation through regulated expression of a CaMKII mediated treatment of inoperable pancreatic carcinoma. Lancet, 357: 1591Ð1592, transgene. Science (Wash. DC), 274: 1678Ð1683, 1996. 2001. 191. Bohl, D., Naffakh, N., and Heard, J. M. Long-term control of erythropoietin 165. Lohr, M., Hummel, F., Faulmann, G., Ringel, J., Saller, R., Hain, J., Gunzburg, secretion by doxycycline in mice transplanted with engineered primary myoblasts. W. H., and Salmons, B. Microencapsulated, CYP2B1-transfected cells activating Nat. Med., 3: 299Ð305, 1997.

8572

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research. Harnessing Apoptosis for Improved Anticancer Gene Therapy

David J. Waxman and Pamela S. Schwartz

Cancer Res 2003;63:8563-8572.

Updated version Access the most recent version of this article at: http://cancerres.aacrjournals.org/content/63/24/8563

Cited articles This article cites 190 articles, 81 of which you can access for free at: http://cancerres.aacrjournals.org/content/63/24/8563.full#ref-list-1

Citing articles This article has been cited by 10 HighWire-hosted articles. Access the articles at: http://cancerres.aacrjournals.org/content/63/24/8563.full#related-urls

E-mail alerts Sign up to receive free email-alerts related to this article or journal.

Reprints and To order reprints of this article or to subscribe to the journal, contact the AACR Publications Subscriptions Department at [email protected].

Permissions To request permission to re-use all or part of this article, use this link http://cancerres.aacrjournals.org/content/63/24/8563. Click on "Request Permissions" which will take you to the Copyright Clearance Center's (CCC) Rightslink site.

Downloaded from cancerres.aacrjournals.org on September 24, 2021. © 2003 American Association for Cancer Research.