The Pax-5 Gene: a Pluripotent Regulator of B-Cell Differentiation and Cancer Disease

Published OnlineFirst November 29, 2011; DOI: 10.1158/0008-5472.CAN-11-1874

Cancer Review Research

The Pax-5 Gene: A Pluripotent Regulator of B-cell Differentiation and Cancer Disease

Pierre O'Brien1,2, Pier Morin Jr1, Rodney J. Ouellette1,2, and Gilles A. Robichaud1,2

Abstract The Pax-5 oncogene encodes a potent transcription factor that plays a key role in B-cell development and cancerous processes. In normal B-lymphopoiesis, Pax-5 accomplishes a dual function by activating B-cell commitment genes while concomitantly repressing non–B-lineage genes. Given the pivotal importance of Pax-5–mediated processes in B-cell development, an aberrant regulation of Pax5 expression has consistently been associated with B-cell cancers, namely, lymphoma and lymphocytic leukemias. More recently, Pax-5 gene expression has been proposed to influence carcinogenic events in tissues of nonlymphoid origin by promoting cell growth and survival. However, in other cases, Pax-5 products have opposing effects on proliferative activity, thus redefining its generally accepted role as an oncogene in cancer. In this review, we attempt to summarize recent findings about the function and regulation of Pax-5 gene products in B-cell development and related cancers. In addition, we present new findings that highlight the pleiotropic effects of Pax-5 activity in a number of other cancer types. Cancer Res; 71(24); 1–6. 2011 AACR.

Introduction cell identity during subsequent differentiation. At the onset of B lymphopoiesis, Pax-5 repressors are overcome by early B-cell Pax-5, or B-cell–specific activator protein, was initially char- factor-1 (EBF-1)–mediated chromatin remodeling, which ulti- acterized in the context of B-cell commitment, where it was mately activates Pax-5 expression and initiates B-cell commit- shown to be essential for B-cell maturation beyond the early ment (3). Pax-5 is initially expressed at a pro-B stage and is pro-B stage (1). Recent developments have led to the identi- maintained until plasma cell differentiation occurs, during fication of Pax-5 expression in several non–B-cell cancers and to which time it activates the transcription of genes belonging a better understanding of the upstream activators and down- to the pre–B-cell receptor signaling network as well as a series stream effectors that revolve around this transcription factor. of secondary transcription factors that further strengthen the We begin this review with an emphasis on malignant diseases commitment to the B-cell lineage (4, 5). Concomitantly, Pax-5 other than B-cell–derived malignancies in which Pax-5 has also represses B-cell lineage–inappropriate genes (4). Pax-5 is been shown to be deregulated. Subsequently, wedescribe the thus considered as a central regulator of the B-cell gene key factors that activate, interact with, or are transcriptionally expression program. regulated by Pax-5, and we highlight how these interactions are In addition to its role in B cells, Pax-5 has been linked to the important for tumor formation and metastasis. development of other tissue types. During mouse embryogen- esis, Pax-5 expression is observed in the mesencephalon and Pax-5 in Development and Cancer the spinal cord (2). Accordingly, Pax-5 null mice have altered morphogenesis of the midbrain. In this context, Pfeffer and Role of Pax-5 in development colleagues (6) showed that Pax-5 expression is activated by The paired box (Pax) genes encode for a family of develop- structurally related Pax-2 and other homeodomain proteins mentally regulated transcription factors that serve central through direct binding of an enhancer sequence within the functions in cell differentiation and tissue development (2). Pax-5 gene. They also showed that Pax-5 was expressed in a Pax-5 is required for B-cell commitment, as evidenced by the specific temporal and spatial pattern during the formation of maintenance of pluripotency observed in Pax-5–deficient pro- the midbrain–hindbrain boundary of transgenic mouse embry- B cells (1). Additionally, Pax-5 ensures the maintenance of B- os, which is an essential step preceding the development of the midbrain and cerebellum in the vertebrate embryo. Pax-5 transcription is regulated through the activation of 2 Authors' Affiliations: 1Departement de Chimie et Biochimie, Universitede Moncton; 2Atlantic Cancer Research Institute, Moncton, New Brunswick, known alternative promoters. This generates transcripts with Canada distinct first exons, 1A and 1B, with otherwise identical in- Corresponding Author: Gilles A. Robichaud, Faculty of Science, Room A- frame sequences. Moreover, alternative splicing events 212, Universite de Moncton, Moncton, NB E1A 3E9, Canada. Phone: 506- throughout the transcript generate multiple protein isoforms 858-4320; Fax: 506-858-4541; E-mail: [email protected] (7). However, due to the inherent challenges of isoform variant doi: 10.1158/0008-5472.CAN-11-1874 analysis, not much is known about the contribution of the 2011 American Association for Cancer Research. Pax-5 variant proteins in normal and cancerous contexts. As a

www.aacrjournals.org OF1

O'Brien et al.

result, their respective functional significance is poorly under- samples. Specifically, 57 of the 242 samples analyzed were stood. However, recent studies have begun to shed light on the found to have genetic alterations resulting in loss of function of expression of Pax-5 protein variants as well as their putative Pax-5. In contrast to a proposed tumor-promoting model function in both normal and malignant B cells, as discussed commonly described for Pax-5, the tumor-suppressor/haploin- further below. sufficiency model is corroborated by the works of Cobaleda and colleagues (16) and Heltemes-Harris and colleagues (17), Pax-5 in B-cell malignancies which support Pax-5 tumor-suppressor properties in B-cell Given its pivotal regulatory function in B-cell development, malignancies. These dichotomous events mediated by Pax-5 Pax-5 can be considered an attractive candidate for involve- in cancer cells (pro-oncogenic versus tumor suppressor) ment in B-cell oncogenesis, and accordingly, its aberrant appear to be context dependent. Further investigation is thus expression is correlated with aggressive subsets of B-cell needed to clarify what specific intracellular environment will non-Hodgkin lymphoma (8). Furthermore, in lymphoplasmo- dictate Pax-5 function in cancer processes. As will be discussed cytoid lymphoma, the Pax-5 gene is often implicated in a throughout this review, dichotomous functions of Pax-5 in recurrent chromosomal rearrangement that places most of cancer are commonly observed and are not limited to B-cell the protein coding sequences under transcriptional control of malignancies. the potent promoters of the immunoglobulin heavy chain (IgH) gene leading to elevated Pax-5 transcription (9). To gain Pax-5 expression in nonhematopoietic cancers knowledge about Pax-5 chromosomal translocations in human Pax-5 expression has also been observed in a growing num- tumors, Souabni and colleagues (10) reconstructed a human t ber of cancers of nonhematopoietic origin. Recently, Pax-5 (9;14) translocation in a germline mutant knockin mouse by expression has been linked to nonlymphoid cancers such as inserting a Pax-5 minigene into the IgH locus (IgHP5ki). astrocytomas, medulloblastomas, neuroblastomas, oral carci- Consequently, forced Pax-5 expression in the hematopoietic nomas, colorectal carcinomas, cervical carcinomas, bladder lineage interfered with normal T-cell development, which led carcinomas, and small-cell lung carcinomas. In most cases, to the formation of immature T-lymphoblastic lymphomas in Pax-5 expression correlates with increasing disease malignancy. IgHP5ki mice, suggesting that the T-lymphoid lineage is also Furthermore, recent findings have shown that Pax-5 expression particularly sensitive to the oncogenic program of Pax-5. is present in breast cancer (18, 19) and is thought to be involved Although the oncogenic contributions of Pax-5 in B-cell in metastatic progression (20). Taken together, these results cancerous lesions have yet to be completely elucidated, it add to the growing body of evidence that implicates Pax-5 acti- seems that downstream perturbation of the B-cell receptor vity in diverse nonhematopoietic solid tumor malignancies. signaling network of genes can, at least in part, account for its role in B lymphomagenesis (11). Pax-5 Functions in Oncogenic Processes Pax-5 deregulation is also associated with certain types of acute leukemia, particularly B-cell precursor acute lympho- Pax-5 as a driver of tumor progression blastic leukemia (B-ALL). Pax-5 has been shown to be closely Findings suggest that Pax-5 function is associated with correlated with this form of leukemia and may become a hallmark cancer cell processes such as proliferation, apoptosis, reliable marker for the diagnosis of this disease. Fluorescence and phenotype transitioning. In mouse B-cell lymphoma cell in situ hybridization studies are revealing an increasing num- lines, Pax-5 stimulates cell growth, an effect that is reversed ber of chromosomal translocations involving Pax-5 in B-ALL upon pharmacologic inhibition of B-cell receptor components that result in the expression of novel chimeric proteins. Some activated by Pax-5 (11). Similarly, Pax-5 protein expression of Pax-50s fusion partners encode themselves for transcription positively correlates with proliferation of neuroblastoma cells factors, such as ETV6 (12), or encode for functionally diverse (21) and likely is involved in human growth hormone–induced proteins, such as JAK2 tyrosine kinase (13). Thus far, in all proliferation of breast carcinoma cells, because nuclear trans- reported Pax-5 fusions, the chimeric proteins retain the N- location and activity of Pax-5 are increased upon autocrine terminal DNA-binding domain of Pax-5; consequently, these stimulation (19). Furthermore, Pax-5 has been linked to cell proteins are likely to retain the putative DNA-binding and survival, mainly through its involvement in apoptosis path- target specificity, albeit with altered regulatory properties. This ways. Recently, it was shown that individual Pax-5 isoforms is exemplified by an ectopic expression study of the Pax-5– may have specific effects in apoptosis (22). In a B-ALL cell ETV6 fusion protein that showed that normally activated Pax-5 model using a novel ribozyme-derived isoform–specific knock- target genes become dominantly repressed by the fusion down system, Robichaud and colleagues (22) showed that a protein in vitro, leading to apoptotic resistance in affected reduction of the Pax-5B isoform reduces cell viability by cells (14). inducing apoptotic cell death. They also found that the loss Although studies have shown that in some instances Pax-5 of Pax-5B isoform expression led to an increase in Pax-5A genetic lesions result in expression of proteins with dominant expression, and they suggested an autoregulatory effect oncogenic functions, as discussed above, other reports have between the 2 distinct promoter-driven isoforms. The obser- provided evidence in support of haploinsufficiency-inducing vation of interregulating capabilities between Pax-5 variants Pax-5 mutations in B-ALL. In particular, Mullighan and col- has also been made in murine models (23). A link between leagues (15) identified a series of Pax-5 copy number changes in Pax-5 expression and apoptosis was also revealed in a study of a large-scale screening of genetic alterations in B-ALL patient multiple myeloma cell lines, in which the authors found that

OF2 Cancer Res; 71(24) December 15, 2011 Cancer Research

Pleiotropic Effects of the Pax-5 Gene

Pax-5 overexpression promoted apoptosis events (24). Other aberrant Pax-5 expression in B-cell malignancies, so far no studies suggest a growth-inhibitory function for Pax-5. Of note, translocations involving the Pax-5 locus have been found in Pax-5 slightly decreases proliferation rates in hepatocellular characterized small-cell lung carcinoma cell lines (26), sug- carcinoma cell lines (25) as well as in selected breast carcinoma gesting an alternate mechanism for Pax-5 ectopic expression. cell lines (18). In general, Pax-5 seems to confer a progrowth The exploration of specific signaling events that activate Pax-5 effect in lymphoid cells and an inhibitory effect in nonlym- is critical for our understanding of the pathogenesis of these phoid tissues. cancers and may lead to the identification of potential therapeutic strategies aimed at targeting the Pax-5 pathway. Dichotomous roles of Pax-5 in metastasis A recent study identified metastasis-associated protein 1 In addition to its involvement in proliferation and cell fate (MTA1) as a regulator of Pax-5 transcription (28). Although its events, Pax-5 has been implicated in tumor metastasis. Find- role in metastasis is unclear, MTA1 expression strongly corre- ings in a neuroblastoma cell model revealed that Pax-5 over- lates with invasiveness and angiogenesis in many cancers, expression led to an increase in colony formation in soft agar including breast cancer. A study using chromatin immuno- (21). Furthermore, Pax-5 directly activates transcription of c- precipitation revealed MTA1 binding to an enhancer sequence Met (26), a receptor tyrosine kinase involved in cell motility and within the Pax-5 gene in MCF-7 breast carcinoma cells (28). angiogenesis in small-cell lung cancer. These results implicate This interaction was subsequently investigated in B-cell Pax-5 as a promoter of aggressiveness in certain cancer types. lymphoma, where MTA1 directly induces transcription of In contrast, Vidal and colleagues (18) showed that Pax-5 Pax-5, an effect that is dependent on acetylation of MTA1. Of reduces colony formation and promotes epithelial behavior in interest, histone acetyltransferase (HAT) p300 interacts with breast carcinoma cells. They also reported that recombinant and acetylates Pax-5 to enhance its transcriptional activity. Pax-5 overexpression in invasive MDA-MB231 cells reduced Taken together, these findings are consistent with an involve- migration and motility. The same study showed that siRNA- ment of Pax-5 in metastasis, and they underscore acetylation as mediated depletion of endogenous Pax-5 in MCF-7 cells an important posttranslational modification that regulates enhanced cell migration. These findings suggest that Pax-5 Pax-5 transcription and activity. contributes to the mesenchymal–epithelial transition, a pro- Recent evidence provides reason to suspect that the JAK2/ cess that is required for successful colonization of tumors to STAT5 pathway is involved in Pax-5 regulation. One study secondary metastatic locations. Indeed, cancer cells are revealed a STAT5 binding motif within the Pax-5 gene and thought to transiently undergo phenotype transitioning to showed that phosphorylated STAT5 enhances activation of the accommodate the different stages of the metastatic process. Pax-5 promoter in pre-B cells (29). Subsequently, another Accordingly, mesenchymal properties are advantageous to report indicated that JAK2 activation induces DNA-binding cancer cells for extracellular matrix degradation and intrava- ability and nuclear compartmentalization of Pax-5 in breast sation toward blood vessels, whereas an epithelial phenotype carcinoma cells (19). Taken together, these results suggest 2 favors metastatic tumor formation and recapitulation of pri- means by which the JAK2/STAT5 pathway could potentially mary tumor characteristics. Of interest, a gene expression modulate Pax-5 activity in cancer cells: (i) through the regu- microarray analysis revealed a 100-fold overexpression of lation of Pax-5 localization and (ii) through the activation of Pax-5 in breast cancer cells that metastasized to lymph nodes STAT5-mediated transcription (Fig. 1). On the other hand, compared with the primary tumor (27). Moreover, Pax-5 has an inverse correlation between Pax-5 and STAT5 was recently been shown to suppress the expression of the proinvasive focal reported by Heltemes-Harris and colleagues (17), who de- adhesion kinase, reminiscent of the mesenchymal–epithelial scribed a mechanism in which reduced expression of Pax-5 transition (20). Collectively, these findings suggest the involve- and EBF1 synergizes with STAT5 overactivation to initiate ment of Pax-5 in breast cancer and its progression to B-ALL. A number of studies have implicated aberrant activa- metastasis. tion of STAT5 in breast and hematopoietic cancers. Further The seemingly conflicting functions exhibited by Pax-5 investigation will help clarify the relationship between JAK2/ appear to be highly dependent on precise cellular contexts STAT5 signaling and Pax-5, and the potential of the JAK2/ and suggest a complex spectrum of functions for Pax-5 and STAT5 pathway as a target for inhibition. possibly its numerous isoforms in different cell backgrounds. Further studies aimed at elucidating the downstream signaling Interacting partners pathways regulated by Pax-5 will likely prove to be the key in Several proteins have been reported to interact directly with understanding its role in cancer cells. Pax-5. Of note, Pax-5 recruits the Ets-1 oncoprotein and enhances its DNA-binding ability at the promoter of the mb-1 Pax-5 Signaling in Cancer gene (30). The Ets-1 protein is a transcription factor, and its aberrant expression is associated with numerous cancers in Upstream regulation which it acts to promote the transcription of genes involved in High-throughput gene expression analysis has led to the tumor invasiveness and angiogenesis. Of interest, Ets-1 stimu- identification of various downstream Pax-5 effectors. However, lates c-Met transcription (31), which is also a transcriptional the upstream signaling networks that are involved in aberrant target of Pax-5 (ref. 26; see above). Moreover, both Ets-1 and Pax-5 activity in cancer processes remain largely unidentified. Pax-5 are expressed in astrocytomas and breast cancer cell Although genomic instability seems to be at the root of lines (18, 31). Although the physiologic relevance of the

www.aacrjournals.org Cancer Res; 71(24) December 15, 2011 OF3

O'Brien et al.

Figure 1. Novel cancer-associated signaling pathways that regulate Pax-5 expression and activity. Aberrant receptor tyrosine kinase activation by human growth hormone leads to activation of JAK2 and nuclear translocation of Pax-5, both of which are inhibited by AG490, a speciﬁc JAK2 inhibitor. JAK2 also phosphorylates (P) STAT5, which induces its translocation to the nucleus, resulting in Pax-5 transcription. HAT activity is also important for Pax-5 regulation because MTA1 transcriptionally activates Pax-5 upon acetylation (Ac), whereas HAT p300 acetylates Pax-5 to increase target gene transcription. Among the Pax-5 target genes are many cancer-associated proteins, such as p53, hTERT, and mesenchymal markers [i.e., matrix metalloproteinase 2 (MMP-2), vimentin, and c-Met]. The Pax-5–mediated transcriptional control of these target genes is highly dependent on cellular context and is discussed throughout this review.

Pax-5/Ets-1 interaction has not been investigated beyond ing a means by which Pax-5 could contribute to proliferative the normal B cell, it would be of great interest to explore events. possible interactions between these 2 proteins in a carcino- An interesting link between the Pax-5 interacting proteins genic model to assess any synergistic effect that could con- discussed herein is that they are all elements of promyelocytic tribute to oncogenesis. leukemia protein nuclear bodies. These dynamic nuclear The death-domain–associated protein Daxx also interacts structures regulate many cellular processes, such as apoptosis, with Pax-5 (32). Daxx localizes to both cytoplasmic and nuclear proliferation, and senescence. It is compelling to think that compartments. In the former, it binds to transmembrane Pax-5 might contribute to tumorigenesis by competitively protein FAS and potentiates FAS-induced apoptosis. In the interfering with key components of promyelocytic leukemia latter, it acts as a transcriptional coregulator with diverse protein nuclear bodies and negatively influencing their tumor- transcription factors. A yeast 2-hybrid assay identified Daxx suppressive properties. as a potential coregulator of Pax-5, and further analysis revealed that it either enhanced or repressed Pax-5 transcrip- Downstream targets tional activity depending on the cell context (32). Further study Many studies have aimed to identify downstream effectors will help elucidate the interaction between these 2 proteins of Pax-5 that could account for its oncogenic role. Stuart and and their effect on the transcription of downstream targets. colleagues (34) explored a possible relationship between Pax-5 Pax-5 has also been shown to interact with the tumor- and p53 expression in human astrocytomas, and they observed suppressor retinoblastoma protein (33). The hypophosphory- an inverse correlation between Pax-5 mRNA and p53 expres- lated form of retinoblastoma protein interacts with Pax-5, as sion in this malignancy. Additionally, a Pax-5 binding site exists shown by coimmunoprecipitation experiments in B cells. within the p53 transcript, and Pax-5 overexpression reduces Curiously, this finding was not explored in more detail, and p53 expression levels in NIH3T3 mouse fibroblasts. In contrast, further clarification of this interaction may reveal a seques- Pax-5 activates p53 promoter-driven luciferase in MCF-7 cells tering of active retinoblastoma protein by Pax-5, thus present- (18).

OF4 Cancer Res; 71(24) December 15, 2011 Cancer Research

Pleiotropic Effects of the Pax-5 Gene

Recently, telomerase reverse transcriptase (hTERT) was isoform and the ratios present in cells when attempting to identified as a Pax-5 transcriptional target (35). The hTERT understand Pax-5 pathways. Another determining factor is the gene encodes for the catalytic subunit of the telomerase cellular environment. Many of the conflicting results discussed enzyme and is the limiting factor for its activity. Telomerase herein are likely due to the cellular environment and its reverse transcriptase expression is inactivated in differentiated functions where Pax-5 is expressed. In this context, a recent somatic cells, but it is restored in many immortalized tumor study revealed that Pax-5 overexpression leads to an increase cells. Of interest, it was shown that Pax-5 directly activates of CD19 transcription in B-AML cell lines but not in epithelial hTERT transcription in a Burkitt lymphoma cell line through cells, where the chromatin of the CD19 promoter is inacces- binding of a Pax-5 consensus sequence within the first exon of sible (38). Collectively, these findings might provide some the hTERT gene (35). This finding suggests an additional means insight into why such functional variability of Pax-5 is observed by which Pax-5 could enhance cell survival in cancer. among different cell types, as well as offer promising avenues of Large-scale microarray studies have enabled the identifica- research that could ultimately lead to the development of tion of many Pax-5 activated and repressed target genes therapeutic interventions. involved in a variety of biologic processes not commonly ascribed to Pax-5 function. For example, Schebesta and col- Conclusions leagues (36) found that Pax-5 modulates the transcription of genes involved in migration and adhesion in B cells. Murine Pax-5 is recognized as an important contributor to normal Pax-5–positive pro-B cells have decreased migration and hematopoiesis and organogenesis in complex organisms. Fur- increased adhesion compared with Pax-5 / pro-B cells. These thermore, the involvement of Pax-5 in B-cell cancers and other findings are consistent with the observations of Vidal and malignant diseases is generally accepted. However, much colleagues (18) discussed above, and they present specific remains to be elucidated with regard to its precise function target genes through the modulation of which Pax-5 may in all cancer types. The role of Pax-5 in the metastatic process is manifest phenotypic transitioning in metastasis. The latter one such example that will likely garner strong interest in the study also demonstrates the effect of Pax-5 on mesenchymal future. At the molecular level, knowledge about the upstream marker expression. In MCF-7 cells, Pax-5 decreases MMP-2, pathways that influence Pax-5 expression and its subsequent vimentin, and fibronectin transcript levels. Moreover, immu- downstream targets will not only lead to a better understand- nostaining of tumor sections reveals that Pax-5 promotes the ing of the complex role of Pax-5 and other Pax-related genes localization of b-catenin to the site of cell–cell contact, thus but also provide significant insight into the molecular biology increasing adhesion at intercellular junctions. of cancer. The involvement of Pax-5 in signaling cascades (e.g., Pridans and colleagues (37) identified a series of Pax-5– Jak/STAT) and chromatin remodeling components (e.g., modulated target genes with functions in cell motility and MTA1) sheds light on the lesser-known epigenetic functions adhesion in B cells. Their data revealed the repression of an associated with this transcription factor (25, 37) and may adhesion molecule, Embigin, by Pax-5. This finding is in slight eventually lead to promising new strategies for cancer therapy. contrast to the reports mentioned above, which support a Overall, the interesting research avenues currently under study proadhesion function for Pax-5. Similarly, Pax-5 activates will help clarify the multiple roles of Pax-5. transcription of a potent promotility oncogene in small-cell lung cancer cells (26). These are clear illustrations of how Pax-5 Disclosure of Potential Conflicts of Interest can stimulate the transcription of genes with opposing cellular activities in a context-dependent fashion. No potential conflicts of interest were disclosed. The complexity of Pax-5 signaling is increased at many levels. First is the expression of multiple Pax-5 protein variants Grant Support through alternative splicing events. Numerous studies have Atlantic Innovation Foundation (R.J. Ouellette); New Brunswick Inno- shown that many of the Pax-5 isoforms maintain DNA-binding vation Foundation and Beatrice Hunter Cancer Research Institute (G.A. ability but have different or truncated regulatory domains (7). Robichaud and P.J. Morin); Canadian Institutes of Health Research (New Consequently, expressed alternatively spliced variants of the Investigator award to G.A. Robichaud and graduate student scholarship to Pax-5 gene have the ability to alter the transactivational P. O'Brien). fi potential of the target gene's expression. These ndings under- Received June 2, 2010; revised August 9, 2011; accepted August 11, 2011; score the importance of establishing the identity of the Pax-5 published OnlineFirst November 29, 2011.

References 1. Busslinger M. Transcriptional control of early B cell development. Annu 4. Holmes ML, Pridans C, Nutt SL. The regulation of the B-cell gene Rev Immunol 2004;22:55–79. expression programme by Pax5. Immunol Cell Biol 2008;86:47–53. 2. Robson EJ, He SJ, Eccles MRA. A PANorama of PAX genes in cancer 5. Delogu A, Schebesta A, Sun Q, Aschenbrenner K, Perlot T, Busslinger and development. Nat Rev Cancer 2006;6:52–62. M. Gene repression by Pax5 in B cells is essential for blood cell 3. Decker T, Pasca di Magliano M, McManus S, Sun Q, Bonifer C, Tagoh homeostasis and is reversed in plasma cells. Immunity 2006;24: H, et al. Stepwise activation of enhancer and promoter regions of the B 269–81. cell commitment gene Pax5 in early lymphopoiesis. Immunity 6. Pfeffer PL, Bouchard M, Busslinger M. Pax2 and homeodomain 2009;30:508–20. proteins cooperatively regulate a 435 bp enhancer of the mouse Pax5

www.aacrjournals.org Cancer Res; 71(24) December 15, 2011 OF5

O'Brien et al.

gene at the midbrain-hindbrain boundary. Development 2000;127: blastoma cells and increases tumorigenicity of a S-type cell line. 1017–28. Carcinogenesis 2004;25:1839–46. 7. Robichaud GA, Nardini M, Laflamme M, Cuperlovic-Culf M, Ouellette 22. Robichaud GA, Perreault JP, Ouellette RJ. Development of an isoform- RJ. Human Pax-5 C-terminal isoforms possess distinct transactivation specific gene suppression system: the study of the human Pax-5B properties and are differentially modulated in normal and malignant B transcriptional element. Nucleic Acids Res 2008;36:4609–20. cells. J Biol Chem 2004;279:49956–63. 23. Lowen M, Scott G, Zwollo P. Functional analyses of two alternative 8. Krenacs L, Himmelmann AW, Quintanilla-Martinez L, Fest T, Riva A, isoforms of the transcription factor Pax-5. J Biol Chem 2001;276: Wellmann A, et al. Transcription factor B-cell-specific activator protein 42565–74. (BSAP) is differentially expressed in B cells and in subsets of B-cell 24. Proulx M, Cayer MP, Drouin M, Laroche A, Jung D. Overexpression of lymphomas. Blood 1998;92:1308–16. PAX5 induces apoptosis in multiple myeloma cells. Int J Hematol 9. Poppe B, De Paepe P, Michaux L, Dastugue N, Bastard C, Herens C, 2010;92:451–62. et al. PAX5/IGH rearrangement is a recurrent finding in a subset of 25. Liu W, Li X, Chu ES, Go MY, Xu L, Zhao G, et al. Paired box gene 5 is a aggressive B-NHL with complex chromosomal rearrangements. novel tumor suppressor in hepatocellular carcinoma through interac- Genes Chromosomes Cancer 2005;44:218–23. tion with p53 signaling pathway. Hepatology 2011;53:843–53. 10. Souabni A, Jochum W, Busslinger M. Oncogenic role of Pax5 in the T- 26. Kanteti R, Nallasura V, Loganathan S, Tretiakova M, Kroll T, Krishnas- lymphoid lineage upon ectopic expression from the immunoglobulin wamy S, et al. PAX5 is expressed in small-cell lung cancer and heavy-chain locus. Blood 2007;109:281–9. positively regulates c-Met transcription. Lab Invest 2009;89:301–14. 11. Cozma D, Yu D, Hodawadekar S, Azvolinsky A, Grande S, Tobias JW, 27. Ellsworth RE, Seebach J, Field LA, Heckman C, Kane J, Hooke JA, et al. et al. B cell activator PAX5 promotes lymphomagenesis through A gene expression signature that defines breast cancer metastases. stimulation of B cell receptor signaling. J Clin Invest 2007;117: Clin Exp Metastasis 2009;26:205–13. 2602–10. 28. Balasenthil S, Gururaj AE, Talukder AH, Bagheri-Yarmand R, Arrington 12. Cazzaniga G, Daniotti M, Tosi S, Giudici G, Aloisi A, Pogliani E, et al. T, Haas BJ, et al. Identification of Pax5 as a target of MTA1 in B-cell The paired box domain gene PAX5 is fused to ETV6/TEL in an acute lymphomas. Cancer Res 2007;67:7132–8. lymphoblastic leukemia case. Cancer Res 2001;61:4666–70. 29. Hirokawa S, Sato H, Kato I, Kudo A. EBF-regulating Pax5 transcription 13. Nebral K, Konig€ M, Harder L, Siebert R, Haas OA, Strehl S. Identifi- is enhanced by STAT5 in the early stage of B cells. Eur J Immunol cation of PML as novel PAX5 fusion partner in childhood acute 2003;33:1824–9. lymphoblastic leukaemia. Br J Haematol 2007;139:269–74. 30. Fitzsimmons D, Lukin K, Lutz R, Garvie CW, Wolberger C, Hagman J. 14. Fazio G, Palmi C, Rolink A, Biondi A, Cazzaniga G. PAX5/TEL acts as a Highly cooperative recruitment of Ets-1 and release of autoinhibition transcriptional repressor causing down-modulation of CD19, by Pax5. J Mol Biol 2009;392:452–64. enhances migration to CXCL12, and confers survival advantage in 31. Dittmer J. The biology of the Ets1 proto-oncogene. Mol Cancer 2003; pre-BI cells. Cancer Res 2008;68:181–9. 2:29. 15. Mullighan CG, Goorha S, Radtke I, Miller CB, Coustan-Smith E, Dalton 32. Emelyanov AV, Kovac CR, Sepulveda MA, Birshtein BK. The interac- JD, et al. Genome-wide analysis of genetic alterations in acute lym- tion of Pax5 (BSAP) with Daxx can result in transcriptional activation in phoblastic leukaemia. Nature 2007;446:758–64. B cells. J Biol Chem 2002;277:11156–64. 16. Cobaleda C, Jochum W, Busslinger M. Conversion of mature B cells 33. Eberhard D, Busslinger M. The partial homeodomain of the transcrip- into T cells by dedifferentiation to uncommitted progenitors. Nature tion factor Pax-5 (BSAP) is an interaction motif for the retinoblastoma 2007;449:473–7. and TATA-binding proteins. Cancer Res 1999;59 (7 Suppl):1716s–24s; 17. Heltemes-Harris LM, Willette MJ, Ramsey LB, Qiu YH, Neeley ES, discussion 24s–5s. Zhang N, et al. Ebf1 or Pax5 haploinsufficiency synergizes with STAT5 34. Stuart ET, Haffner R, Oren M, Gruss P. Loss of p53 function through activation to initiate acute lymphoblastic leukemia. J Exp Med PAX-mediated transcriptional repression. EMBO J 1995;14:5638–45. 2011;208:1135–49. 35. Bougel S, Renaud S, Braunschweig R, Loukinov D, Morse HC 3rd, 18. Vidal LJ, Perry JK, Vouyovitch CM, Pandey V, Brunet-Dunand SE, Bosman FT, et al. PAX5 activates the transcription of the human Mertani HC, et al. PAX5alpha enhances the epithelial behavior telomerase reverse transcriptase gene in B cells. J Pathol 2010;220: of human mammary carcinoma cells. Mol Cancer Res 2010;8: 87–96. 444–56. 36. Schebesta A, McManus S, Salvagiotto G, Delogu A, Busslinger GA, 19. Vouyovitch CM, Vidal L, Borges S, Raccurt M, Arnould C, Chiesa J, Busslinger M. Transcription factor Pax5 activates the chromatin of key et al. Proteomic analysis of autocrine/paracrine effects of human genes involved in B cell signaling, adhesion, migration, and immune growth hormone in human mammary carcinoma cells. Adv Exp Med function. Immunity 2007;27:49–63. Biol 2008;617:493–500. 37. Pridans C, Holmes ML, Polli M, Wettenhall JM, Dakic A, Corcoran LM, 20. Crapoulet N, O'Brien P, Ouellette RJ, Robichaud GA. Coordinated et al. Identification of Pax5 target genes in early B cell differentiation. J expression of Pax-5 and FAK1 in metastasis. Anticancer Agents Med Immunol 2008;180:1719–28. Chem 2011;11:643–9. 38. Walter K, Cockerill PN, Barlow R, Clarke D, Hoogenkamp M, Follows 21. Baumann Kubetzko FB, Di Paolo C, Maag C, Meier R, Schafer€ BW, GA, et al. Aberrant expression of CD19 in AML with t(8;21) involves a Betts DR, et al. The PAX5 oncogene is expressed in N-type neuro- poised chromatin structure and PAX5. Oncogene 2010;29:2927–37.

OF6 Cancer Res; 71(24) December 15, 2011 Cancer Research

The Pax-5 Gene: A Pluripotent Regulator of B-cell Differentiation and Cancer Disease

Pierre O'Brien, Pier Morin, Jr, Rodney J. Ouellette, et al.

Cancer Res Published OnlineFirst November 29, 2011.

Updated version Access the most recent version of this article at: doi:10.1158/0008-5472.CAN-11-1874

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/early/2011/11/29/0008-5472.CAN-11-1874. Click on "Request Permissions" which will take you to the Copyright Clearance Center's (CCC) Rightslink site.