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Endocrine-Related (2000) 7 257–269

Apoptosis in mammary gland and cancer

R Kumar, R K Vadlamudi and L Adam

Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA (Requests for offprints should be addressed to R Kumar, The University of Texas M. D. Anderson Cancer Center, Box 108, 1515 Holcombe Blvd, Houston, Texas 77030, USA)

Abstract Homeostasis in normal tissue is regulated by a balance between proliferative activity and cell loss by . Apoptosis is a physiological mechanism of cell loss that depends on both pre-existing and de novo synthesis, and the process of apoptosis is integral to normal mammary gland development and in many diseases, including cancer. The mammary gland is one of the few systems in that completes its morphologic development postnatally during two discrete physiologic states, and . The susceptibility of the mammary gland to tumorigenesis is influenced by its normal development, particularly during stages of puberty and pregnancy that are characterized by marked alterations in breast cell proliferation and differentiation. Numerous epidemiologic studies have suggested that specific details in the development of the mammary gland play a critical role in risk. Mammary gland development is characterized by dynamic changes in the expression profiles of Bcl-2 family members. The expression of Bcl-2 family proteins in breast cancer is also influenced by and by progestin. Since the ratio of proapoptotic to antiapoptotic proteins determines apoptosis or cell survival, levels may have important implications in the therapeutic prevention of breast cancer.

Introduction mammary gland development and . Because of the nature and depth of the information available on this Breast cancer is the leading type of cancer in women and is subject, we could only include representative studies, and we the second leading cause (after cancer) of cancer death apologize to those whose work could not be covered. among women. In the United States in 1998, an estimated Extensive information is, however, available in earlier 178 700 new cases of breast cancer were expected to be reviews (Carson & Ribeiro 1993, Williams & Smith 1993, diagnosed, and 43 500 women were expected to die of this Reed 1994, Steller 1995, Medina 1996, Baik et al. 1998, disease. Approximately 2 000 000 women have been Benz 1998, Krajewski et al. 1999, Schorr et al. 1999b). diagnosed with breast cancer (NCI statistics 1998). Breast cancer also occurs in men, although far more rarely than in women (approximately 1600 cases in men were diagnosed in Apoptosis 1998); treatment for breast cancer in men is guided by our Homeostasis in normal tissue is regulated by a balance understanding of the disease in women. between proliferative activity and cell loss by apoptosis. Our limited understanding of the biology and Apoptosis is a physiological mechanism of cell loss that developmental genetics of the normal mammary gland has depends on both pre-existing proteins and de novo protein been a barrier to progress in treating breast cancer. Much synthesis (Williams & Smith 1993, Steller 1995, Thompson of the biological research in the recent past has focused on 1995), and the process of apoptosis is integral to normal understanding the initiation and development of the disease. mammary gland development (Medina 1996). Apoptosis Data from the emerging models suggest that we need to plays an important role during development, metamorphosis, better understand crucial signaling components in the normal and organ and in many diseases, including cancer mammary gland before any beneficial impact on the (Steller 1995, Thompson 1995). Apoptosis is characterized prevention and treatment of breast cancer can be expected. by nuclear condensation and fragmentation and by In this review, we summarize some of the data from the degradation of DNA into oligonucleosome fragments last 10years about the role, the expression, and the regulation (Thompson 1995). of apoptosis regulatory proteins (Bcl-2 family proteins, The results of some studies suggest that cells derived caspases, Fas ligand, and transcription factors) in normal from our have a decreased capacity to

Endocrine-Related Cancer (2000) 7 257–269 Online version via http://www.endocrinology.org 1351-0088/00/007–257  2000 Society for Endocrinology Printed in Great Britain Downloaded from Bioscientifica.com at 09/25/2021 05:08:56PM via free access R Kumar et al.: Apoptosis in breast cancer undergo apoptosis in response to various physiological Mammary gland development stimuli (Carson & Ribeiro 1993, Thompson 1995). Thus, a defect in apoptosis may be involved in aberrant survival, the The mammary gland is one of the few organ systems in development of breast cancer or both, and deregulation of mammals that completes its morphologic development apoptosis may be involved in the development of breast postnatally during two discrete physiologic states, puberty cancer by the enhancement of cell survival and development and pregnancy. Thus the mammary gland is an excellent of drug resistance by breast cancer cells. model for studying normal morphologic development and the Apoptosis is a highly regulated process. One important early steps of tumor formation (Nandi 1959, Medina 1996). regulator of apoptosis is Bcl-2, a 26 kDa protein that protects Mammary gland growth and maturation consist of a cells against apoptosis in a variety of experimental systems series of highly ordered events involving interactions among (Reed 1994). Bcl-2 protein is primarily localized to the several distinct cell types. These are regulated by complex nuclear envelope, the endoplasmic reticulum, and the outer interactions among many steroid and growth mitochondrial membranes (Krajewski et al. 1993, Lithgow et factors. In 4-week-old mice, the mammary glands become al. 1994). increasingly sensitized to elevations in ovarian hormones, Apoptosis is also regulated by a number of genes, which signal the terminal end buds (club-shaped epithelial including Bcl-2 and related family members (such as Bcl-x, structures) to grow away from the region to fill the fat Bax, and Bad), which have significant structural homology pad. During this rapid but tightly regulated growth phase, with the Bcl-2 gene (Hockenbery et al. 1991, Korsmeyer an extensive network of epithelial ductal, tree-like branching 1992, Boise et al. 1993, Oltvai et al. 1993). The Bcl-x gene develops. When the expanding mammary ductal mass gives rise to two distinct mRNAs by differential splicing that reaches the limits of its fat pad, the structures are permanently replaced by mitotically quiescent encodes Bcl-xL and Bcl-xS proteins. Bcl-xL is related to Bcl-2 terminal end ducts and alveolar buds (Fig. 1). At the onset in inhibiting apoptosis. In contrast, Bcl-xS is a dominant negative inhibitor of both Bcl-2 and Bcl-xL. Different of pregnancy, rapid epithelial-cell proliferation begins again, members of the Bcl-2 family have been shown to form resulting in additional ductal branching and lobuloalveolar homo- and heterodimers and it appears that the ratio of Bcl-2 growth from the ductal skeleton. These alveoli are the to Bax, other family members, or both may play a regulatory functional units of production at , the time at role in apoptosis. It has been proposed that some of these which the gland is fully differentiated. After lactation ceases, interactions may be tissue specific (Sedlak et al. 1995). the gland undergoes massive restructuring and apoptosis, Apoptosis plays an important role during the involution leading to involution and return of the primary ductal of the mammary gland. The 6-fold increase in the ratio of structures (Nandi 1959, Medina 1996, Daniels & Siberstein

Bcl-xS to Bcl-xL during the first 2 days of involution suggests 1987). that apoptotic proteins play a role in predisposing mammary In the normal mammary tissue in male mice, the alveolar cells to cell death immediately after lactation. condenses around the center of the mammary

Figure 1 Schematic representation of various stages of mammary gland development.

258 Downloaded from Bioscientifica.comwww.endocrinology.org at 09/25/2021 05:08:56PM via free access Endocrine-Related Cancer (2000) 7 257–269 bud at days 13–15 of gestation, and the cells of the cord die. characterized by gene products which are conditionally Thus, a small cord of epithelial cells is detached from the switched on or off during this phase of the mammary gland skin and the mammary gland does not extend to the surface. development. After of the pups, the mammary gland No further development occurs. Apoptosis in the mammary involutes and proceeds through a rapid remodeling process cord of males has been shown to be induced by that reduces the tissue to a state resembling the mature virgin secretion, which targets the mesenchyme to destroy the gland. Some of the associated changes include the loss of epithelial cells (Durnberger & Kratochwil 1980). secretory alveolar cells, the proteolytic degradation of the , and the disappearance of lobuloalveolar Mammary gland carcinogenesis structures. The majority of cells that die during involution undergo apoptosis (Guenette et al. 1994, Strange et al. 1995), The susceptibility of the mammary gland to tumorigenesis being characterized by cellular condensation and nuclear is influenced by its normal development, particularly during fragmentation. They are eventually engulfed by macro- stages of puberty and pregnancy that are characterized by phages. The transition from lactation to involution is marked alterations in breast cell proliferation and accompanied by the proteolytic degradation of the supporting differentiation. Numerous epidemiologic studies have and the systemic reduction in hormone suggested that specific details in the development of the levels (Strange et al. 1995, Lund et al. 1996). The rapid mammary gland play a critical role in breast cancer risk inactivation of milk-protein genes, mild ischemia, and (Kelsy & Gammon 1990). increased intraluminal pressure are other phenotypic changes Some of the risk factors for breast cancer include that could potentially participate in the induction of cell death nulliparity or first full-term pregnancy after age 30, early and tissue remodeling (Richards & Benson 1971, menarche, late , and a family history of breast Schmitt-Ney et al. 1992a,b). cancer (Rondinelli et al. 1995). In contrast, early parity, late menarche, early menopause, and long periods of lactation Bcl-2 family members in mammary gland provide protective effects against breast cancer (Russo & apoptosis Russo 1980, 1982, Henderson et al. 1993). Therefore, systemic endocrine patterns and reproductive changes that The Bcl-2 (B-cell leukemia/lymphoma 2) gene was first occur in the human breast have important implications for identified at the breakpoint of a chromosomal translocation breast cancer. t(14:18) in B-follicular lymphoma (Tsuijimoto et al. 1985). The observation that the same endocrine events control It encodes a 26 kDa protein that protects cells against mammary development and influence breast cancer risk apoptosis. Overexpression of Bcl-2 has been shown to strengthens the hypothesis that mammary gland development suppress the initiation of apoptosis in response to a number and carcinogenesis are fundamentally linked. In addition, it of stimuli, including anticancer drugs in a number of systems is believed that the pluripotent cap cells play a key role in (Sentman et al. 1991, Hickman 1992, Dole et al. 1994, mammary gland carcinogenesis. For example, exposure of Teixeira et al. 1995). Furthermore, inhibition of Bcl-2 early-stage mammary glands to carcinogens resulted in expression by antisense oligonucleotide (Teixeira et al. significant mutations associated with malignant 1995), and dominant negative inhibitor Bcl-xS (Sumantran et transformation and increased the susceptibility to tumor al. 1995) has been shown to promote apoptosis and sensitize formation (Russo & Russo 1980, 1982). These hormonal risk cells to chemotherapy-induced apoptosis. factors provide clues for target-cell predisposition to breast Mammary gland development is characterized by cancer. dynamic changes in the expression profiles (both mRNA and A balance between proliferation, differentiation, and protein) of Bcl-2 family members (Table 1). For example, death in the stem-cell population and throughout the cells Bax and Bcl-x are expressed evenly throughout mammary of the mammary gland is critical for normal development. gland development. However, the levels of expression of Bak Perturbations in this balance can contribute to cancer and Bad increase during late pregnancy and lactation, and development. Conditions that upregulate cell proliferation or these remain expressed at the time of maximal apoptotic downregulate apoptosis can allow the accumulation of involution. In contrast, Bcl-w (a new cell-death-suppressor mutations that contribute to the subsequent development of member of Bcl2 family) was expressed in pregnancy and breast cancer. It is not clear, however, how normal lactation but was downregulated at the onset of apoptosis. mechanisms and signaling pathways controlling growth and Bcl-2 is expressed in the mammary gland of the apoptosis in the human breast act in the development of non-pregnant and during early pregnancy but was tumors, in the protection from tumor development, or in undetectable in the lactating or early-involuting dissemination. gland. In contrast, the expression of Bcl-xS, Bcl-xL and Bax Involution, an essential component of the mammary continues through late pregnancy, is downregulated during gland remodeling program, has been extensively lactation, and is upregulated with the start of involution www.endocrinology.org Downloaded from Bioscientifica.com at 09/25/2021259 05:08:56PM via free access R Kumar et al.: Apoptosis in breast cancer

Table 1 Genes reportedly involved in mammary gland involution. Gene Presumptive time Identified aberrations References containing or citing evidence for of action during the mammary roles in involution gland involution Apoptosis Survival Bcl-2 family Bax 1st day up Heermeier et al. (1996) Knudson et al. (1995) Bcl-x first 2 days up Bak 1st stage up Bad 1st stage up Bcl-w down Bcl-2 undetectable Schorr et al. (1999) Jager et al. (1997) Bfl-1 up

Bcl-xS/xL first 2 days up Heermeier et al. (1996) Mitochondrial genes Lactoferrin days 1, 2 and 3 up Lee et al. (1996) Ferritin heavy chain days 1, 2, 3 and 4 up Cytochrome oxidase days 4 and 7 up Subunit 1 and 2 Cytochrome b day 7 up Transcription factors STAT3 up Chapman et al. (1999) STAT5 down Streuli et al. (1995) STAT1 up, in absence of Chapman et al. (1999) STAT3 p53 1st stage no role Li et al. (1996) functional Jerry et al. (1999) NF-1 up (repressor role) Furlong et al. (1996) NF-kB 2nd stage up Clarkson et al. (2000) STAT5A up Humphreys & Hennighausen (1999) ESX prolonged up Marti et al. (1999) PKA 1st and 2nd up AP1 1st and 2nd up Marti et al. (1999) JNK 1st and 2nd up Marti et al. (1999) Oct-1 days 1, 2, 3 and 4 down Marti et al. (1999) Tyrosine phosphatases PTPs prolonged up Aoki et al. (1999) LAR Schaapveld et al. (1997)

(Heermeier et al. 1996). Bak, Bad, Bcl-w, and Bfl-1 are also first stage of involution and increases cell survival 70% upregulated during involution (Schorr et al. 1999a). These during the second stage of involution. Bcl-2 function has results support a model in which mammary epithelial cells been shown to have a greater effect on the regulation of are primed for apoptosis during the transition from pregnancy mammary epithelial-cell survival in vivo than the loss of Bax to lactation by the de novo expression of the death-effectors function (Schorr et al. 1999). Deletion of the Bcl-2 gene from Bak and Bad. It has been suggested that the anti-apoptotic the genome had no overt effects on embryogenesis and Bcl-2 family proteins prevent the apoptotic function of Bak mammary gland development, indicating that Bcl-2 does not and Bad until involution, when the levels of Bcl-w decline play a dominant role in mammary gland remodeling (Veis et

(Metcalfe et al. 1999). al. 1993). On the other hand, mice lacking functional Bcl-xL The Bcl-2 gene product represents the prototype of the died during embryogenesis, and massive cell death was antiapoptotic family of genes that regulate apoptosis observed in their nervous systems.

(Hockenbery et al. 1990, Oltvai et al. 1993). Overexpression The expression of proapoptotic Bcl-xS and Bax, unlike of Bcl-2 inhibits alveolar-cell apoptosis during involution that of Bcl-2, has been shown to increase within the first day and accelerates c-myc-induced tumorigenesis of the after weaning, coinciding with the onset of apoptosis mammary gland in transgenic mice (Jager et al. 1997). Bcl-2 (Heermeier et al. 1996). These events are associated with a gain of function mutation reduces apoptosis 50% during the decrease in the expression of milk proteins, a reduction in

260 Downloaded from Bioscientifica.comwww.endocrinology.org at 09/25/2021 05:08:56PM via free access Endocrine-Related Cancer (2000) 7 257–269 signal transduction through Stat5a and 5b, and the potential to induce apoptosis by sequestering IGF-I to casein activation of STAT3 (Li et al. 1997). micelles, thus preventing it from binding to its receptor. Stat5 The rise in the levels of Bax during the first day of activity, in contrast to that of STAT3, is downregulated at involution does not depend on the presence or absence of the start of involution, a phenomenon that appears to be p53. In one study, the Bax protein was detected after weaning required for transduction of survival signals from the in increasing numbers of cells, peaking at day 3 and extracellular matrix (Streuli et al. 1995). The physiologic decreasing thereafter. Bax-deficient mice displayed significance of Stats during apoptosis was established by hyperplasia in their lymphoid system, showed enhanced cell studies with STAT3-null mammary gland; these studies death in their reproductive organs (Knudson et al. 1995) and showed Stat1 activation and increases in the levels of p53 exhibited aberrant mammary gland development (Shibata et and p21, which may act as compensatory mechanisms for the al. 1999). eventual initiation of involution (Chapman et al. 1999). Bcl-x is another homolog of Bcl-2 and exists in two There were no marked differences in the regulation of Stat5, isoforms, Bcl-xL and Bcl-xS. The Bcl-xS splice variant of Bcl-xL, or Bax in the absence of STAT3.

Bcl-x was shown to promote cell death, and Bcl-xL was The p53 has an established role in apoptosis, but its shown to have a protective function. Low levels of Bcl-xS participation in mammary gland involution remains unclear. mRNA and protein, present during lactation even in the In one study, the absence of p53 in p53 knockout mice had absence of detectable apoptosis, are followed by sharp no apparent effect on involution (Li et al. 1996). These increases during the first 2 days of involution. The ratio of investigators examined the process of involution in the

Bcl-xS to Bcl-xL remained stable in the virgin, pregnant, and presence and absence of functional p53 in different mouse lactating gland. However, during the first 2 days of models: wild-type mice, transgenic mice that express simian involution, Bcl-xS expression increased 6-fold more than virus 40(SV40)T-antigen specifically in mammary tissue

Bcl-xL (Heermeier et al. 1996). during pregnancy; and mice that carry non-functional p53 alleles in their germ line. The authors concluded that Mitochondrial genes in mammary gland involution and remodeling, with the concomitant apoptosis disappearance of the lobuloalveolar structures, proceeded normally in the absence of functional p53. In addition, the By using partial sequence analysis, Lee and associates loss of p53 did not affect the expression of Bax or the ratio of determined that expression of iron metabolism-related and RNAs encoding Bcl-xS to Bcl-xL (Li et al. 1996). However, mitochondrial genes was induced during mammary gland investigators using p53−/− mice reported that there was a involution (Lee et al. 1996). The expression of: the delay in mammary gland involution (Jerry et al. 1999). Thus, lactoferrin gene was induced at involution days 1, 2, and 3; involution can be viewed as a biphasic phenomenon in which the ferritin heavy chain gene at involution days 1, 2, 3 and initial responses are sensitive to p53 whereas secondary 4; the cytochrome oxidase subunit 1 and 2 genes at responses are p53-independent (Jerry et al. 1999). A involution days 4 and 7; and the cytochrome b gene at well-characterized p53 target is p21, an inhibitor of involution day 7. These results imply that iron metabolism cyclin-dependent kinase, which may be required for the and mitochondrial function may be altered during mammary induction of apoptosis (Duttaroy et al. 1997). Similar results gland involution (Lee et al. 1996). were obtained when a region of SV40was expressed under the control of the whey acidic milk-protein promoter (WAP) Transcription factors in mammary gland in mammary gland epithelial cells (Tzeng et al. 1998). The apoptosis authors reported that SV40T/t-antigen synthesis causes premature mammary gland involution during late pregnancy The transition of the lactating mammary gland to involution by inducing apoptosis and leads to the development of is controlled by a series of gene products which are regulated mammary tumors after the first lactation period in both by several transcription factors, including STAT3, AP-1, p53-positive (WAP-SV-T/t) and p53-negative double- p53, Stats, Ets isoforms, C/EBPδ, NF-1, and c-Myc (Strange transgenic animals (WAP-SV-T/t.p53−/−) (Tzeng et al. et al. 1992, Li et al. 1997, Furlong et al. 1996, Chapman et 1998). al. 1999, Gigliotti & DeWille 1999, Clarkson & Watson The nuclear factor 1 (NF1) family of transcription factors 1999, Clarkson et al. 2000). has been shown to be critical for the tissue-specific STAT3 is a well-studied transcription factor during transcription driving epithelial cell-specific milk-protein mammary gland involution. Recent studies suggest that expression in the mammary gland, of a range of genes insulin-like I (IGF-I)-binding protein selectively expressed in terminal differentiation. (Marti et al. (IGFBP)-5 may be a downstream target of STAT3 during 1999). By using biochemical assays, Furlong and associates involution (Chapman et al. 1999). Since epithelial cells detected that induction of a 74 kDa NF1 protein was induced synthesize and secrete high levels of IGFBP-5, it has in mouse mammary gland during involution and not during www.endocrinology.org Downloaded from Bioscientifica.com at 09/25/2021261 05:08:56PM via free access R Kumar et al.: Apoptosis in breast cancer lactation, as was the case for other NF1 proteins, of 110, 68, binding activity was transiently induced, and the AP-1 and 46 kDa (Furlong et al. 1996). complex was composed principally of cFos/JunD. In contrast, both the Oct-1 DNA binding activity and the Oct-1 Pathways upregulated during mammary protein were gradually reduced during the first 4 days of gland involution involution, although Oct-1 mRNA levels remained unchanged. Comparing nuclear extracts from normal Until recently, it was accepted that two series of events mammary glands with nuclear extracts from glands which 3 regulate distinct stages of mammary involution: the weeks after had been cleared of all epithelial cells progressive gain of death signals and the loss of survival revealed that PKA activation, AP1 induction, and Oct-1 factors. An emerging view, however, suggests that mammary inactivation depend on the presence of the epithelial involution also involves the activation of specific survival compartment. The increased Fos/Jun expression and the factors. For example, a stage-specific pattern of NF-ΚB inactivation of Oct-1 could be the consequences of the activation was observed in the mammary gland during increased PKA activity (Marti et al. 1994). postlactational involution, a period of extensive apoptosis of luminal epithelial cells (Clarkson et al. 2000). The results Tyrosine phosphatase in mammary gland Κ of that study suggested that NF- B performs a homeostatic development function during involution since its activity is maximally induced at the onset of the second phase of involution when Recent studies have revealed that at the involution stage after disrupt cell-extracellular matrix interactions. In weaning, most protein tyrosine phosphatases (PTPs) are another study, Stat5A activation in the mammary gland upregulated, and their level of expression returned to almost antagonized regression and involution-mediated virgin levels. Such upregulation was also induced by forced apoptosis (Humphreys & Hennighausen 1999). The results weaning in lactating mother mice. These results suggest that of that study suggested that Stat5A acts as an antecedent, PTPs contribute to the development, involution, and acting molecules that initiate the process of epithelial remodeling of the mammary gland and may inhibit the regression and reorganization during involution. expression levels of milk genes during lactation (Aoki et al. The epithelial restricted with serine box (ESX), a novel 1999). The results of another study showed that mammary member of the erythroblast transformation specific domain glands of Leukocyte-common Antigen-Related Molecule (ETS) family of transcription factors is another molecule that (LAR) −/− were incapable of delivering milk has been shown to be maximally expressed during involuting because of an impaired terminal differentiation of alveoli at mouse and rat mammary glands. The prolonged elevation of late pregnancy (Schaapveld et al. 1997). As a result, the ESX levels in fully regressed mammary glands suggests that glands failed to switch to a lactational state and showed a ESX expression can be induced by soluble growth factors rapid involution postpartum. and maximally upregulated in the epithelial cells destined to survive both the apoptotic and remodeling phases of Bcl-2 pathway in breast cancer cells and glandular involution (Marti et al. 1999). tumors Nuclear activation of protein kinase A and transcription factor-activator protein 1 (AP1) also precede the irreversible Bcl-2 is an oncogene that contributes to malignancy by phase of involution that is characterized by internucleosomal inhibiting apoptosis and thereby extending cell survival and DNA fragmentation (Jaggi et al. 1996). Activation of AP1 is one of the most studied apoptotic genes in breast cancer and fragmentation of chromosomal DNA can be prevented (Table 2). Investigators analyzed apoptosis in untreated by lactogenic hormone treatment in explant cultures derived human and adjacent invasional from mammary tissue at lactation. The authors showed that cancer and demonstrated that spontaneous apoptosis is lost the elevation in AP1 coincides with the epithelial expression concurrently with invasive transformation (Bodis et al. of sulfated 2, a potential target gene of AP1 1995). Breast epithelium is known to undergo periodic (Jaggi et al. 1996). In another study, Marti and associates fluctuations in Bcl-2 levels and apoptosis during the described signal-transduction events, such as activation of menstrual cycle (Sabourin et al. 1994). The expression of protein kinase A, Jun-N-terminal kinase (JNK) and AP1 Bcl-2 is known to fluctuate with the normal ovulatory cycle; during the early and late phases of mammary gland its levels are modulated in a hormone-dependent manner involution, and suggested that this pathway plays a role in within premenopausal breast ductal epithelial cells (Nathan regulating and coordinating involution with an emphasis on et al. 1993, Sabourin et al. 1994). It has been demonstrated the apoptotic process of involution (Marti et al. 1999). that the expression of Bcl-2 in human breast Elevated nuclear protein kinase A (PKA) activity was adenocarcinomas is significantly associated with hormone– observed from postlactation day 1, paralleled by increasing receptor positivity and low histologic grade (Alsabeh et al. levels of components of the AP1 complex. AP1 DNA 1996). Bcl-2 protein was detected in 80% of the breast

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Table 2 Expression of Bcl-2 family genes in breast cancer cells and tumors. Gene Expression status Presumptive mechanism References Bcl-2 Detected in 80% of breast cancers Inhibition of apoptosis Krajewski et al. (1999) expression inversely related to cell cycle changes Kapranos et al. (1997) metastasis loss correlated with high chemiresistance van Slooten et al. (1998) proliferation and tumor grade suppression of p21/WAF Knowlton et al. (1998) MMP-9 secretion Ricca et al. (2000) Cooperation with ER VEGF expression Bukholm et al. (1997) Cooperation with oncogenes Wang & Phang et al. (1995) Biroccio et al. (2000) Del Bufalo et al. (1997) Bag1 Over expressed in breast cancer cells Regulation of Bcl-2 activity Yang (1999) and primary tumors Brimmell et al. (1999) Bax Low expression in breast cancer cells Reduction in apoptosis, Krajewski et al. (1997) and malignant breast tissue chemosensitivity Kapranos et al. (1997) Some correlation with low expression Wagener et al. (1996) and shorter overall survival Li et al. (1999) Caspases Increase in expression of caspases 3, Zapata et al. (1998) 6, 8 and their inhibitors in invasive Krajewski et al. (1999) breast cancers Drugs NO, etoposide and flavopiridol Induction of apoptosis Umansky et al. (2000) activates caspases in cancer cells Li et al. (2000) Benjamin et al. (1998) FasL Increase in expression of FasL in Elimination of tumor infiltrating immune Mottolese et al. (2000) majority of breast tumors cells and facilitation of tissue Reimer et al. (2000) Fas positive tumors associated with destruction during invasion metastatic nodes and larger tumor size cancers derived from women, and Bcl-2-positive patients had receptor (ER) repression, and DNA aneuploidy. a better prognosis and survival rate than did Bcl-2-negative Eighty-five percent of Bcl-2-positive tumors were ER patients (reviewed in Krajewski et al. 1999). Bcl-2 and, to a positive and 65% were aneuploid, while only 28% of lesser degree, Bax expression was inversely related to the Bcl-2-negative tumors were ER positive and 37% were distant metastases. A combined analysis of the ratio of Bcl-2 aneuploid (Eissa et al. 1999). Estradiol markedly increased to Bax expression in relation to clinical outcome showed that Bcl-2 protein content, in both short- and long-term treatments the absence of both factors was more strongly associated of MCF-7 cells, and anti- (4-hydroxytamoxifen and with the development of distant metastases. These findings RU 58668) reversed this effect. Estrogen treatment had little suggested that Bcl-2 and Bax apoptosis-related proteins effect on the Bax mRNA level. In addition, pretreatment with could serve as good prognostic indicators in node-negative estradiol protected MCF-7 cells from apoptosis (Wang & breast cancer patients, and their combined absence may Phang 1995). Estrogen regulation of Bcl-2 gene expression imply a potential deregulation of the apoptotic process, in breast cancer cells involves multiple enhancer elements, which in turn could contribute to the biologic aggressiveness including Sp1 and CRE element, but does not require direct of the tumors (Kapranos et al. 1997). The suppression of binding of the with Bcl-2 promoter DNA p21WAF1 expression was proposed as one of the (Dong et al. 1999). Anti-estrogens, such as tamoxifen, have mechanisms by which Bcl-2 prevents apoptosis. A highly been shown to induce apoptosis in breast cancer cells by significant association was reported between reduced downregulating Bcl-2. Tamoxifen did not, however, affect p21WAF1-protein expression and overexpression of Bcl-2 in Bax, Bcl-xL, or p53 expression at the mRNA or protein levels tumors (Bukholm et al. 1997). (Zhang et al. 1997, 1999). The expression of Bcl-2 family proteins in breast cancer A number of mechanisms by which Bcl-2 exerts its is also influenced by estradiol and progestin (Kandouz et al. positive growth-supporting effects and its anti-apoptotic 1996). Since the ratio of proapoptotic to antiapoptotic function have been proposed. It has been shown that Bcl-2 proteins determines apoptosis or cell survival, hormone plays a role in the regulation of cell division. High levels may have important implications in the therapeutic proliferation rates and high tumor grade (Bloom – prevention of breast cancer (Krajewski et al. 1999). A strong, Richardson grading scheme) have been shown to be strongly positive association was observed between Bcl-2 and associated with the absence of Bcl-2 expression. The loss www.endocrinology.org Downloaded from Bioscientifica.com at 09/25/2021263 05:08:56PM via free access R Kumar et al.: Apoptosis in breast cancer of Bcl-2 expression was strongly correlated with increased ER-positive tumors, but was undetectable or weakly apoptotic and necrotic cell death, high proliferation rates and expressed in ER-negative tumors. A correlation was also high tumor grade (van Slooten et al. 1998). Other observed between ER and Bag-1 in breast cancer-derived cell investigators showed that Bcl-2 overexpression prolongs lines (Brimmell et al. 1999). Immunolocalization studies cell-cycle progression by increasing doubling time with an antibody that recognizes all three isoforms of Bag-1 (Knowlton et al. 1998). Decreased tumor proliferation may revealed that Bag-1 is expressed in the cytosol and nuclei of account for the association of Bcl-2 expression with a normal mammary epithelial cells but was found favorable outcome in breast cancer, even though Bcl-2 may predominantly in the cytosol in invasive carcinomas (Turner mediate chemoresistance in some patients (Knowlton et al. et al. 1997). Bag-1 was shown to regulate retinoid activities 1998). through its interactions with retinoic acid receptor (RAR). Bcl-2 has also been shown to work in combination with The overexpression of Bag-1 in MCF-7 and ZR 75–1 breast hypoxia to modulate vascular endothelial growth factor cancer cells reduced the ability of the all transretinoic acid (VEGF) expression and the in vivo angiogenic response in to inhibit cell growth and induce apoptosis (Liu et al. 1998). doxorubicin-resistant MCF7 cells (Biroccio et al. 2000). Bcl-2 protein also contributes to oncogenesis; in cooperation Bax in breast cancer cells and tumors with known oncogenes such as c-myc, ras, or viral genes, Bcl-2 can transform and immortalize cells. In animal models, An analysis of Bax expression in human breast cancer Bcl-2–overexpressing clones induce a significantly higher specimens revealed the localization of Bax in normal number of experimental and spontaneous lung metastases mammary epithelium. Bax-alpha, a splice variant of Bax that than do the control transfectant clone (Del Bufalo et al. promotes apoptosis, is expressed in high amounts in normal 1997). cell lines and breast tissue but is expressed only weakly or Because overexpression of human epidermal growth not at all in cancer cell lines and malignant tissue (Bargou et factor receptor-2 (HER-2) in MCF-7 cells results in al. 1995). The results of some studies have shown a upregulation of anti-apoptotic proteins Bcl-2 and Bcl-xL, correlation between the loss of Bax expression and shorter deregulation of anti-apoptotic Bcl-2 and Bcl-xL may be overall patient survival and faster tumor progression associated with the enhanced survival of HER-2– (Krajewski et al. 1997, Kapranos et al. 1997). Despite the overexpressing and ER-positive breast cancer cells (Kumar ability of p53 to bind directly to the Bax gene promoter, the et al. 1996). In some breast cancer cells the overexpression regulation of Bax in human breast cancers does not correlate of heregulin, a ligand of HER-3 and HER-4 receptors, has with p53 status, implying that regulation of this pro-apopotic been shown to induce apoptosis, and heregulin over- gene in these tumours is complex and probably influenced expression has been shown to downregulate expression of by several factors (Krajewski et al. 1997). The expression of Bcl-2 (Weinstein et al. 1998). Overexpression of Bcl-2 in the the pro-apoptotic protein Bax did not correlate with either human breast cancer cell line (MCF-7ADR) enhances the cell Bcl-2 expression or the frequency of apoptotic cells (van line’s tumorigenicity and metastatic potential by inducing Slooten et al. 1998). Increased degradation of the Bax protein metastasis-associated properties such as increased secretion via the ubiquitin proteosomal pathway was reported as one of the -9 (MMP-9) and enhances mechanism by which cancer cells regulate the expression of NF-B-dependent transcriptional activity (Ricca et al. 2000). Bax (Li & Dou 2000). Inactivating mutations in the Bax gene Basic fibroblast growth factor (bFGF, FGF-2), a classical in colon cancers have been reported (Rampino et al. 1997); transforming factor and angiogenic factor in breast tumors, however until now there was no evidence that these downregulates Bcl-2 expression, and promotes apoptosis in mutations also exist in breast cancers. MCF-7 breast cancer cells (Wang et al. 1998, Maloof et al. Overexpression of Bax also sensitizes breast cancer 1999). MCF-7 cells to cisplatin and etoposide (Sakakura et al. 1997) Bag-1 is an anti-apoptotic protein that binds to and and to radiation-induced apoptosis (Sakakura et al. 1996). enhances the anti-apoptotic activity of Bcl-2 (Takayama et Using the tetracycline-inducible system, the expression of al. 1995). Like Bcl-2, Bag-1 has been shown to interact with Bax-alpha was shown to have no effect on the viability of a number of signaling proteins and receptors, including Raf1 breast cancer cells; however, the expression of Bax-alpha kinase (Wang et al. 1996), platelet-derived growth factor strongly increased the chemosensitivity of breast cancer cells receptor, receptor (Bardelli et al. to epirubicin and this sensitization is due to increased 1996), and nuclear hormone receptors (Prat & Toft 1997). apoptosis (Wagener et al. 1996). The upregulation of Bax Bag-1 mRNA and protein are overexpressed in human breast and p21WAF1 were proposed as the molecular mechanisms cancer cell lines. In one study, the expression of two isoforms by which genistein (a soy isoflavonoid) induces apoptosis in of Bag-1, p46 and p33, was also much higher in breast the breast cancer cells (Li et al. 1999). Using a transgenic primary tumors (Yang et al. 1999). Bag-1 expression has mouse model system Shibata et al. (1999) demonstrated a been detected in normal breast epithelial cells and most role for Bax in inhibiting mammary cancer progression.

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Caspases in breast cancer cells and Mullauer et al. 2000). High levels of FasL mRNA expression tumors in breast carcinomas seems to be positively correlated with histologic grading. A ratio of FasL to Fas mRNA transcripts Caspases are the principal intracellular effectors of apoptosis. greater than one was found to be significantly associated with In a study comparing the intensity of immunostaining in shorter disease-free survival and increased mortality (Reimer normal mammary epithelium with that of invasive et al. 2000). Vitamin E succinate inhibited growth and carcinoma, caspase-3 immunointensity was generally higher induced apoptosis in estrogen receptor-negative human breast in invasive cancers (Zapata et al. 1998). In another study, cancer cells; the pathway implicated was Fas-mediated increases in the expression of caspase-3, -6, and -8 were apoptosis (Turley et al. 1997). associated in parallel with apoptosis and histologic aggressiveness of the breast lesions (Vakkala et al. 1999). Since tumorigenesis is associated with a resistance to apoptosis, enhanced levels of caspases in tumor cells suggest Acknowledgements that caspases may have different functions in tumor cells or We thank Mariann Crapanzano from the Department of may be inactive because of overexpression of inhibitors Scientific Publications for editorial suggestions. This work (Krajewski et al. 1999). Survivin, an inhibitor of apoptosis was supported by National Institutes of Health grants protein (IAP) has been shown to be expressed in a number CA65746, CA 80066 and CA84456 (to R Kumar). of breast cancer cell lines. Survivin binds caspase-3 and -7 and thus may have a role in inhibiting caspase activity and cell death in cells exposed to diverse apoptotic stimuli (Tamm et al. 1998). Nitric oxide, which induces apoptosis in Reference breast cancer cell lines induces activation of caspase-1, -3, and -6, mitochondrial damage but does not require the CD95/ Alsabeh R, Wilson CS, Ahn CW, Vasef MA & Battifora H 1996 CD95L pathway (Umansky et al. 2000). Flavopiridol, a drug Expression of bcl-2 by breast cancer: a possible diagnostic currently used in cancer therapy, inhibits growth and induces application. Modern Pathology 9 439–444. Aoki N, Kawamura M, Yamaguchi-Aoki Y, Ohira S & Matsuda T apoptosis in a number of breast cancer cell lines. One 1999 Down-regulation of protein tyrosine phosphatase gene mechanism by which flavopiridol induces apoptosis is expression in lactating mouse mammary gland. Journal of activation of caspases, specifically caspase-3 (Motwani et al. Biochemistry 125, 669–675. 1999, Li et al. 2000). The activation of caspase-3 was also Baik MG, Lee MJ & Choi YJ 1998 Gene expression during implicated as a mechanism through which topoisomerase involution of mammary gland. International Journal of inhibitor etoposide induces apoptosis in breast cancer cell Molecular Medicine 2 39–44. line MCF-7 (Benjamin et al. 1998). Bardelli A, Longati P, Albero D, Goruppi S, Schneider C, Ponzetto C & Comoglio PM 1996 HGF receptor associates with the anti-apoptotic protein BAG-1 and prevents cell death. EMBO Journal 15 6205–6212. Fas in breast cancer cells and tumors Bargou RC, Daniel PT, Mapara MY, Bommert K, Wagener C, The Fas ligand FasL and its receptor Fas (APO-1 or CD95) Kallinich B, Royer HD & Dorken B 1995 Expression of the are members of the tumor necrosis family. Interaction of bcl-2 gene family in normal and malignant breast tissue: low bax-alpha expression in tumor cells correlates with resistance FasL with its receptor Fas initiates signaling, leading to towards apoptosis. International Journal of Cancer 60 854–859. initiation of an apoptotic pathway. Non-transformed Benjamin CW, Hiebsch RR & Jones DA 1998 Caspase activation mammary epithelial cell lines express high levels of Fas in MCF7 cells responding to etoposide treatment. Molecular mRNA and protein, but several breast cancer cell lines Pharmacology 53 446–450. express low levels of Fas (Keane et al. 1996). In that study, Benz CC 1998 Transcription factors and breast cancer. the level of FasL protein in the majority of breast carcinomas Endocrine-Related Cancer 5 271–282. Biroccio A, Candiloro A, Mottolese M, Sapora O, Albini A, Zupi was higher than that in normal breast tissue or benign breast G & Del Bufalo D 2000 Bcl-2 overexpression and hypoxia disease. A significant association was observed between synergistically act to modulate vascular endothelial growth factor FasL and the presence of metastatic lymph nodes and larger expression and in vivo angiogenesis in a breast carcinoma line. tumor size but Fas expression correlated with node-negative FASEB Journal 14 652–660. status and smaller tumor size. Patients with Fas-positive Bodis S, Siziopikou KP, Schnitt SJ, Harris JR & Fisher DE 1995 tumors exhibited longer disease-free survival than did those Extensive apoptosis in ductal carcinoma in situ of the breast. with Fas-negative carcinoma. (Mottolese et al. 2000). Cold Spring Harbor meeting on Programmed Cell Death, Abstract no. 30. Increased expression of FasL was speculated to confer an Boise LH, Gonzalez-Garcia M, Postema CE, Ding L, Lindsten T, advantage on breast cancer cells, possibly by eliminating Turka LA, Mao X, Nunez G & Thompson CB 1993 Bcl-x, a tumor-infiltrating immune cells, by facilitating tissue bcl-2–related gene that functions as a dominant regulator of destruction during invasion, or both (Gutierrez et al. 1999, apoptotic cell death. Cell 74 597–608. www.endocrinology.org Downloaded from Bioscientifica.com at 09/25/2021265 05:08:56PM via free access R Kumar et al.: Apoptosis in breast cancer

Brimmell M, Burns JS, Munson P, McDonald L, O’Hare MJ, Gutierrez LS, Eliza M, Niven-Fairchild T, Naftolin F & Mor G Lakhani SR & Packham G 1999 High level expression of 1999 The Fas/Fas-ligand system: a mechanism for immune differentially localized BAG-1 isoforms in some oestrogen evasion in human breast carcinomas. Breast Cancer Research receptor-positive human breast cancers. British Journal of and Treatment 54 245–253. Cancer 81 1042–1051. Heermeier K, Benedict M, Li M, Furth P, Nunez G & Bukholm IK, Nesland JM, Karesn R, Jacobsen U & Borresendale Hennighausen L 1996 Bax and Bcl-xs are induced at the onset AL 1997 Interaction between bcl-2 and p21 (WAF1/CIP1) in of apoptosis in involuting mammary epithelial cells. Mechanisms breast carcinomas with wild-type p53. International Journal of of Development 56 197–207. Cancer 73 38–41. Henderson BE, Ross RK & Pike MC 1993 Hormonal Carson DA & Ribeiro JM 1993 Apoptosis and disease. Lancet 341 chemoprevention of cancer in women. Science 259 633–638. 1251–1254. Hickman JA 1992 Apoptosis induced by anticancer drugs. Cancer Chapman RS, Lourenco PC, Tonner E, Flint DJ, Selbert S, Takeda Metastasis Reviews 11 121–139. K, Akira S, Clarke AR & Watson CJ 1999 Suppression of Hockenbery DM, Nunez G, Milliman C, Schreiber RD & epithelial apoptosis and delayed mammary gland involution in Korsmeyer 1990Bcl2 is an inner mitochondrial membrane mice with a conditional knockout of stat3. Genes and protein that blocks programmed cell death. Nature 348 334–336. Development 13 2604–2616. Hockenbery DM, Zutter M, Hickey W, NahmM&Korsmeyer S Clarkson RW & Watson CJ 1999 NF-kappaB and apoptosis in 1991 Bcl2 protein is topographically restricted in tissues mammary epithelial cells. Journal of Mammary Gland Biology characterized by apoptotic cell death. PNAS 88 6961–6965. and Neoplasia 4 165–175. Humphreys RC & Hennighausen L 1999 Signal transducer and Clarkson RW, Heeley JL, Chapman R, Aillet F, Hay RT, Wyllie activator of transcription 5a influences mammary epithelial cell A & Watson CJ 2000 NF-KappaB inhibits apoptosis in murine survival and tumorigenesis. Cell Growth and Differentiation 10 mammary epithelia. Journal of Biological Chemistry 275 12737– 685–694. 12742. Jager R, Heizer U, Schenkel J & Weiher H 1997 Overexpression Daniels CW & Siberstein GB 1987 Postnatal development of the of Bcl-2 inhibits alveolar cell apoptosis during involution and rodent mammary gland. In The Mammary Gland: Development, accelerates c-myc-induced tumorigenesis of the mammary gland Regulation, and Function, pp 3–36. Eds MC Neville & CW in transgenic mice. Oncogene 15 1787–1795. Daniels. New York: Plenum Publishing Corp. Jaggi R, Marti A, Guo K, Feng Z & Friis RR 1996 Regulation of a Del Bufalo D, Biroccio A, Leonetti C & Zupi G 1997 Bcl-2 physiological apoptosis: mouse mammary involution. Journal of overexpression enhances the metastatic potential of a human Dairy Science 79 1074–1084. breast cancer line. FASEB Journal 11 947–953. Jerry DJ, Pinkas J, Kuperwasser C, Dickinson ES & Naber SP Dole M, Nunez G, Merchant AK, Maybaum J, Rode CK, Bloch 1999 Regulation of p53 and its targets during involution of the CA & Castle VP 1994 Bcl-2 inhibits chemotherapy-induced mammary gland. Journal of Mammary Gland Biology and apoptosis in neuroblastoma. Cancer Research 54 3253–3259. Neoplasia 2 177–181. Dong L, Wang W, Wang F, Stoner M, Reed JC, Harigai M, Kandouz M, Siromachkova M, Jacob D, Chretien M, Therwath Samudio I, Kladde MP, Vyhlidal C & Safe S 1999 Mechanisms A & Gompel A 1996 Antagonism between estradiol and of transcriptional activation of bcl-2 gene expression by progestin on Bcl-2 expression in breast-cancer cells. 17beta-estradiol in breast cancer cells. Journal of Biological International Journal of Cancer 68 120–125. Chemistry 274 32099–32107. Kapranos N, Karaiosifidi H, Valavanis C, Kouri E & Vasilaros S Durnberger H & Kratochwil K 1980Specificity of tissue 1997 Prognostic significance of apoptosis related proteins Bcl-2 interaction and origin of mesenchymal cells in the and Bax in node-negative breast cancer patients. Anticancer response of the embryonic mammary gland. Cell 19 465–471. Research 17 2499–2505. Duttaroy A, Qian JF, Smith JS & Wang E 1997 Up-regulated Keane MM, Ettenberg SA, Lowrey GA, Russell EK & Lipkowitz P21CIP1 expression is part of the regulation quantitatively S 1996 Fas expression and function in normal and malignant controlling serum deprivation-induced apoptosis. Journal of breast cell lines. Cancer Research 56 4791–4798. Cellular Biochemistry 64 434–446. Kelsey JL & Gammon MD 1990The epidemiology of breast Eissa S, Labib R, Khalifa A, Swelam N, Khalil F & El-Shenawy cancer. CA – A Cancer Journal for Clinicians 1 2228–2240. AM 1999 Regulators of apoptosis in human breast cancer. Knowlton K, Mancini M, Creason S, Morales C, Hockenbery D & Clinical Biochemistry 32 321–326. Anderson BO 1998 Bcl-2 slows in vitro breast cancer growth Furlong EE, Keon NK, Thornton FD, Rein T & Martin F 1996 despite its antiapoptotic effect. Journal of Surgical Research 76 Expression of a 74–kDa nuclear factor 1 (NF1) protein is 22–26. induced in mouse mammary gland involution. Knudson CM, Tung KS, Tourtellotte WG, Brown GA & Involution-enhanced occupation of a twin NF1 binding element Korsmeyer SJ 1995 Bax-deficient mice with lymphoid in the testosterone-repressed prostate message-2/clusterin hyperplasia and male germ cell death. Science 270 96–99. promoter. Journal of Biological Chemistry 271 29688–29697. Korsmeyer SJ 1992 Bcl2 initiates a new category of oncogenes: Gigliotti AP & DeWille JW 1999 Local signals induce CCAAT/ regulator of cell death. Blood 80 879–886. enhancer binding protein-delta (C/EBP-delta) and C/EBP-beta Krajewski S, Tanaka S, Takayama S, Schibler MJ, Fenton W & mRNA expression in the involuting mouse mammary gland. Reed JC 1993 Investigation of the subcellular distribution of the Breast Cancer Research and Treatment 58 57–63. bcl-2 oncoprotein: residence in the nuclear envelope, Guenette RS, Corbeil HB, Leger J, Wong K, Mezl V, Mooibroek endoplasmic reticulum, and outer mitochondrial membranes. M & Tenniswood M 1994 Induction of gene expression during Cancer Research 53 4701–4714. involution of the lactating mammary gland of the rat. Journal of Krajewski S, Thor AD, Edgerton SM, Moore DH, Krajewska M & Molecular Endocrinology 12 47–60. Reed JC 1997 Analysis of Bax and Bcl-2 expression in p53–

266 Downloaded from Bioscientifica.comwww.endocrinology.org at 09/25/2021 05:08:56PM via free access Endocrine-Related Cancer (2000) 7 257–269

immunopositive breast cancers. Clinical Cancer Research 3 Metcalfe AD, Gilmore A, Klinowska T, Oliver J, Valentijn AJ, 199–208. Brown R, Ross A, MacGregor G, Hickman JA & Streuli CH Krajewski S, Krajewska M, Turner BC, Pratt C, Howard B, Zapata 1999 Developmental regulation of Bcl-2 family protein JM, Frenkel V, Robertson S, Ionov Y, Yamamoto H, Peruch M, expression in the involuting mammary gland. Journal of Cell Takayama S & Reed JC 1999 Prognostic significance of Science 112 1771–1783. apoptosis regulators in breast cancer. Endocrine-Related Cancer Mottolese M, Buglioni S, Bracalenti C, Cardarelli MA, Ciabocco 6 29–40. L, Giannarelli D, Botti C, Natali PG, Concetti A & Venanzi FM. Kumar R, Mandal M, Lipton A, Harvey H & Thompson CB 1996 2000 Prognostic relevance of altered Fas (CD95)-system in Overexpression of HER2 modulates bcl-2, bcl-XL, and human breast cancer. International Journal of Cancer 89 123– tamoxifen-induced apoptosis in human MCF-7 breast cancer 132. cells. Clinical Cancer Research 2 1215–1219. Motwani M, Delohery TM & Schwartz GK 1999 Sequential Lee M, Kim H, Jeon D, Hwang I, Choi B, Myung K, Choi Y, Paik dependent enhancement of caspase activation and apoptosis by S & Baik M 1996 Iron metabolism-related genes and flavopiridol on paclitaxel-treated human gastric and breast cancer mitochondrial genes are induced during involution of mouse cells. Clinical Cancer Research 5 1876–1883. mammary gland. Biochemical and Biophysical Research Mullauer L, Mosberger I, Grusch M, Rudas M & Chott A 2000 Communications 224 164–168. Fas ligand is expressed in normal breast epithelial cells and is Li B & Dou QP 2000 Bax degradation by the ubiquitin/proteosome frequently up-regulated in breast cancer. Journal of Pathology dependent pathway: involvement of tumor survival and 190 20–30. progression. PNAS 97 3850–3855. Nandi S 1959 Hormonal control of mammogenesis and Li M, Hu J, Heermeier K, Hennighausen L & Furth PA 1996 lactogenesis in the C3H/He Crgl mouse. University California Apoptosis and remodeling of mammary gland tissue during Publication Zoology 65 1–128. involution proceeds through p53–independent pathways. Cell Nathan B, Anbazhagan R, Dyer M, Ebbs SR, Jayatilake H & Growth and Differentiation 7 13–20. Gusterson BA 1993 Expression of Bcl-2 like immunoreactivity Li M, Liu X, Robinson G, Bar-Peled U, Wagner KU, Young WS, in the normal breast and in breast cancer. Breast 2 Hennighausen L & Furth PA 1997 Mammary-derived signals 134–137. activate programmed cell death during the first stage of Oltvai Z, Milliman CL & Korsmeyer SJ 1993 Bcl2 heterodimerizes mammary gland involution. PNAS 94 3425–3430. in vivo with a conserved homolog Bax that accelerates Li Y, Bhuiyan M & Sarkar FH 1999 Induction of apoptosis and programmed cell death. Cell 73 609–619. inhibition of c-erbB-2 in MDA-MB-435 cells by genistein. Pratt WB & Toft DO 1997 Steroid receptor interactions with heat International Journal of Oncology 15 525–533. shock protein and immunophilin chaperones. Endocrine Reviews Li Y, Bhuiyan M, Alhasan S, Senderowicz AM & Sarkar FH 2000 3 306–360. Induction of apoptosis and inhibition of c-erbB2 in breast cancer Rampino N, Yamamoto H, Ionov Y, Li Y, Sawai H, Reed JC & cells by flavopiridol. Clinical Cancer Research 6 223–229. Perucho M 1997 Somatic frameshift mutations in the BAX gene Lithgow T, van Driel R, Bertram JF & Strasser A 1994 The in colon cancers of the microsatellite mutator phenotype. Science protein product of the oncogene bcl-2 is a component of the 275 967–969. nuclear envelope, the endoplasmic reticulum, and the outer Reed JC 1994 Bcl2 and the regulation of programmed cell death. mitochondrial membrane. Cell Growth and Differentiation 5 411–417 Journal of Cell Biology 124 1–6. Liu R, Takayama S, Zheng Y, Froesch B, Chen G, Zhang X, Reed Reimer T, Herrnring C, Koczan D, Richter D, Gerber B, Kabelitz JC & Zhang X 1998 Interaction of BAG1 with retinoic acid D, Friese K & Thiesen HJ 2000 FasL: Fas ratio – a prognostic receptor and its inhibition of retinoic acid induced apoptosis in factor in breast carcinomas. Cancer Research 60 822–828. cancer cells. Journal of Biological Chemistry 273 16985–16992. Ricca A, Biroccio A, Del Bufalo D, Mackay AR, Santoni A & Lund LR, Romer J, Thomasset N, Solberg H, Pyke C, Bissell MJ, Cippitelli M 2000 bcl-2 over-expression enhances NF-kappaB Dano K & Werb Z 1996 Two distinct phases of apoptosis in activity and induces mmp-9 transcription in human MCF7 mammary gland involution: proteinase-independent and (ADR) breast-cancer cells. International Journal of Cancer 86 -dependent pathways. Development 122 181–193. 188–196. Maloof P, Wang Q, Wang H, Stein D, Denny TN, Yahalom J, Richards RC & Benson K 1971 Structural changes associated with Fenig E & Wieder R 1999 Overexpression of basic fibroblast inhibition of involution of the mammary gland in the albino rat. growth factor (FGF-2) downregulates Bcl-2 and promotes Journal of Endocrinology 51 137–148. apoptosis in MCF-7 human breast cancer cells. Breast Cancer Rondinelli RH, Haslam SZ & Fluck MM 1995 The role of ovarian Research and Treatment 56 153–167. hormones, age and mammary gland development in polymavirus Marti A, Jehn B, Costello E, Keon N, Ke G, Martin F & Jaggi R mammary tumorigenesis. Oncogene 11 1817–1827. 1994 Protein kinase A and AP-1 (c-Fos/JunD) are induced Russo J & Russo IH 1980Susceptibility of the mammary gland to during apoptosis of mouse mammary epithelial cells. Oncogene carcinogenesis. II. Pregnancy interruption as a risk factor in 9 1213–1223. tumor incidence. American Journal of Pathology 100 Marti A, Lazar H, Ritter P & Jaggi R 1999 Transcription factor 497–512. activities and gene expression during mouse mammary gland Russo J & Russo IH 1982 Differentiation of the mammary gland involution. Journal of Mammary Gland Biology and Neoplasia 4 and susceptibility to carcinogenesis. Breast Cancer Research and 145–152. Treatment 2 5–73. Medina D 1996 The mammary gland: a unique organ for the study Sabourin JC, Martin A, Baruch J, Truc JB, Gompel A & Poitout P of development and tumorigenesis. Journal of Mammary Gland 1994 Bcl-2 expression in normal breast tissue during the Biology and Neoplasia 1 5–19. menstrual cycle. International Journal of Cancer 59 1–6. www.endocrinology.org Downloaded from Bioscientifica.com at 09/25/2021267 05:08:56PM via free access R Kumar et al.: Apoptosis in breast cancer

Sakakura C, Sweeney EA, Shirahama T, Igarashi Y, Hakomori S, Sumantran VN, Ealovega MW, Nunez G, Clarke MF & Wicha MS Nakatani H, Tsujimoto H, Imanishi T, Ohgaki M, Ohyama T, 1995 Overexpression of Bcl-Xs sensitizes MCF-7 cells to Yamazaki J, Hagiwara A, Yamaguchi T, Sawai K & Takahashi chemotherapy-induced apoptosis. Cancer Research 55 2507– T 1996 Overexpression of bax sensitizes human breast cancer 2510. MCF-7 cells to radiation-induced apoptosis. International Takayama S, Sato T, Krajewski S, Kochel K, Irie S, Millan JA & Journal of Cancer 67 101–105. Reed JC 1995 and functional analysis of BAG-1: a Sakakura C, Sweeney EA, Shirahama T, Igarashi Y, Hakomori S, novel Bcl-2–binding protein with anti-cell death activity. Cell 80 Tsujimoto H, Imanishi T, Ogaki M, Ohyama T, Yamazaki J, 279–284. Hagiwara A, Yamaguchi T, Sawai K & Takahashi T 1997 Tamm I, Wang Y, Sausville E, Scudiero DA, Vigna N, Oltersdorf Overexpression of bax sensitizes breast cancer MCF-7 cells to T & Reed JC 1998 IAP-family protein survivin inhibits caspase cisplatin and etoposide. Surgery Today 27 676–679. activity and apoptosis induced by Fas (CD95), Bax, caspases, Schaapveld RQ, Schepens JT, Robinson GW, Attema J, Oerlemans and anticancer drugs. Cancer Research 58 5315–5320. FT, Fransen JA, Streuli M, Wieringa B, Hennighausen L & Teixeira C, Reed JC & Pratt MAC 1995 Estrogen promotes Hendriks WJ 1997 Impaired mammary gland development and chemotherapeutical drug resistance by a mechanism involving function in mice lacking LAR receptor-like tyrosine phosphatase Bcl-2 protooncogene expression in human breast cancer cells. activity. Developmental Biology 188 134–146. Cancer Research 55 3902–3907. Schmitt-Ney M, Happ B, Ball RK & Groner B 1992a Thompson CB 1995 Apoptosis in the pathogenesis and treatment Developmental and environmental regulation of a mammary of disease. Science 267 1456–1462. gland-specific nuclear factor essential for transcription of the Topper YJ & Freeman CS 1980Multiple hormone interactions in gene encoding beta-casein. PNAS 89 3130–3134. the developmental biology of the mammary gland. Physiological Schmitt-Ney M, Happ B, Hofer P, Hynes NE & Groner B 1992b Reviews 60 1049–1106. Mammary gland-specific nuclear factor activity is positively Tsuijimoto Y, Gorham J, Cossman J, Jaffe E & Croce CM 1985 regulated by lactogenic hormones and negatively by milk stasis. The t(14:18) chromosome translocation involved in B-cell Molecular Endocrinology 6 1988–1997. neoplasms results from mistake in VDJ joining. Science 299 Schorr K, Li M, Bar-Peled U, Lewis A, Heredia A, Lewis B, 1390–1393. Knudson CM, Korsmeyer SJ, Jager R, Weiher H & Furth PA Turley JM, Fu T, Ruscetti FW, Mikovits JA, Bertolette DC & 1999a Gain of Bcl-2 is more potent than bax loss in regulating Birchenall-Roberts MC 1997 Vitamin E succinate induces mammary epithelial cell survival in vivo. Cancer Research 59 Fas-mediated apoptosis in estrogen receptor-negative human 2541–2545. breast cancer cells. Cancer Research 57 881–890. Schorr K, Li M, Krajewski S, Reed JC & Furth PA 1999b Bcl-2 Turner B, Krjewska M, Brajewski K, Wang L, Carter D, gene family and related proteins in mammary gland involution Takayama S, Kochel K, Glazer P, Haffty B & Reed JC 1997 and breast cancer. Journal of Mammary Gland Biology and Characterization of the subcellular localization of BAG1 protein Neoplasia 4 153–164. in human breast cancer. Breast Cancer Research and Treatment Sedlak TW, Olltvai ZN, Yang E, Wang K, Boise LH, Thompson 46 69. CB & Korsmeyer SJ 1995 Multiple Bcl-2 family members Tzeng YJ, Zimmermann C, Guhl E, Berg B, Avantaggiati ML & demonstrate selective dimerizations with Bax. PNAS 92 7834– Graessmann A 1998 SV40T/t-antigen induces premature 7838. Sentman CL, Shutter JR, Hockenbery D, Kanagawa O & mammary gland involution by apoptosis and selects for p53 Korsmeyer SL 1991 Bcl-2 inhibits multiple forms of apoptosis missense mutation in mammary tumors. Oncogene 16 2103– but not negative selective in thymocytes. Cell 67 879–898. 2114. Shibata MA, Liu ML, Knudson MC, Shibata E, Yoshidome K, Umansky V, Ushmorov A, Ratter F, Chlichlia K, Bucur M, Bandey T, Korsmeyer SJ & Green JE 1999 Haploid loss of bax Lichtenauer A & Rocha M 2000 Nitric oxide mediated apoptosis leads to accelerated mammary tumor development in C3(1)/ in human breast cancer cells requires changes in mitochondrial SV-40–Tag transgenic mice: reduction in protective apoptotic functions and is independent of CD95. International Journal of response at the preneoplastic stage. EMBO Journal 18 2692– Oncology 16 109–117. 2701. Vakkala M, Paakko P & Soini Y 1999 Expression of caspases 3, 6 van Slooten HJ, van de Vijver MJ, van de Velde CJ & van and 8 is increased in parallel with apoptosis and histological Dierendonck JH 1998 Loss of Bcl-2 in invasive breast cancer is aggressiveness of the breast lesion. British Journal of Cancer 4 associated with high rates of cell death, but also with increased 592–599. proliferate activity. British Journal of Cancer 77 789–796. Veis DJ, Sorenson CM, Shutter JR & Koresmeyer SJ 1993 Steller H 1995 Mechanisms and genes of cellular suicide. Science Bcl-2-deficient mice demonstrate fulminant lymphoid apoptosis, 267 1445–1448. polycystic kidneys, and hypopigmented . Cell 75 229–240. Strange R, Li F, Saurer S, Burkhard A & Friis RR 1992 Apoptotic Wagener C, Bargou RC, Daniel PT, Bommert K, Mapara MY, cell death and tissue remodeling during mouse mammary gland Royer HD & Dorken B 1996 Induction of the death-promoting involution. Development 115 49–58. gene bax-alpha sensitizes cultured breast-cancer cells to Strange R, Friis RR, Bemis LT & Geske FJ 1995 Programmed cell drug-induced apoptosis. International Journal of Cancer 67 138– death during mammary gland involution. Methods in Cell 141. Biology 46 355–368. Wang HG, Takayama S, Rapp UR & Reed JC 1996 Bcl-2 Streuli CH, Edwards GM, Delcommenne M, Whitelaw CB, Burdon interacting protein Bag-1 binds to and activates the kinase Raf-1. TG, Schindler C & Watson CJ 1995 Stat5 as a target for PNAS 93 7063–7068. regulation by extracellular matrix. Journal of Biological Wang Q, Maloof P, Wang H, Fenig E, Stein D, Nichols G, Denny Chemistry 270 21639–21644. TN, Yahalom J & Wieder R 1998 Basic fibroblast growth factor

268 Downloaded from Bioscientifica.comwww.endocrinology.org at 09/25/2021 05:08:56PM via free access Endocrine-Related Cancer (2000) 7 257–269

downregulates Bcl-2 and promotes apoptosis in MCF-7 human Zapata JM, Krajewska M, Krajewski S, Huang RP, Takayama S, breast cancer cells. Experimental Cell Research 238 Wang HG, Adamson E & Reed JC 1998 Expression of multiple 177–187. apoptosis-regulatory genes in human breast cancer cell lines and Wang TT & Phang JM 1995 Effects of estrogen on apoptotic primary tumors. Breast Cancer Research and Treatment 47 129– pathways in human breast cancer cell line MCF-7. Cancer 140. Research 55 2487–2489. Zhang GJ, Kimijima I, Abe R, Kanno M, Katagata N, Hara K, Weinstein EJ, Grimm S & Leder P 1998 The oncogene heregulin Watanabe T & Tsuchiya A 1997 Correlation between the induces apoptosis in breast epithelial cells and tumors. Oncogene expression of apoptosis-related bcl-2 and p53 oncoproteins and 17 2107–2113. the carcinogenesis and progression of breast carcinomas. Clinical Williams GT & Smith CA 1993 Molecular regulation of apoptosis: Cancer Research 3 2329–2335. genetic controls on cell death. Cell 74 777–779. Zhang GJ, Kimijima I, Onda M, Kanno M, Sato H, Watanabe T, Yang X, Hao Y, Ding Z, Pater A & Tang SC 1999 Differential Tsuchiya A, Abe R & Takenoshita S 1999 Tamoxifen-induced expression of antiapoptotic gene BAG-1 in human breast normal apoptosis in breast cancer cells relates to down-regulation of and cancer cell lines and tissues. Clinical Cancer Research 5 bcl-2, but not Bax and Bcl-X (L), without alteration of p53 1816–1822. protein levels. Clinical Cancer Research 5 2971–2977.

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