title: Cyclin D1 repressor domain mediates proliferation and survival in prostate cancer.
abstract: Regulation of the androgen receptor (AR) is critical to prostate cancer (PCa) development; therefore, AR is the first line therapeutic target for disseminated tumors. Cell cycle-dependent accumulation of cyclin D1 negatively modulates the transcriptional regulation of AR through discrete, CDK4-independent mechanisms. The transcriptional corepressor function of cyclin D1 resides within a defined motif termed repressor domain (RD), and it was hypothesized that this motif could be utilized as a platform to develop new strategies for blocking AR function. Here, we demonstrate that expression of the RD peptide is sufficient to disrupt AR transcriptional activation of multiple, prostate-specific AR target genes. Importantly, these actions are sufficient to specifically inhibit S-phase progression in AR-positive PCa cells, but not in AR-negative cells or tested AR-positive cells of other lineages. As expected, impaired cell cycle progression resulted in a suppression of cell doubling. Additionally, cell death was observed in AR-positive cells that maintain androgen dependence and in a subset of castrate-resistant PCa cells, dependent on Akt activation status. Lastly, the ability of RD to cooperate with existing hormone therapies was examined, which revealed that RD enhanced the cellular response to an AR antagonist. Together, these data demonstrate that RD is sufficient to disrupt AR-dependent transcriptional and proliferative responses in PCa, and can enhance efficacy of AR antagonists, thus establishing the impetus for development of RD-based mimetics.
authors.affiliation: Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Schiewer
authors.forename: L M
authors.initials: LM
authors.lastname: Morey
authors.forename: C J
authors.initials: CJ
authors.lastname: Burd
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: D E
authors.initials: DE
authors.lastname: Merry
authors.forename: S-M
authors.initials: SM
authors.lastname: Ho
authors.forename: K E
authors.initials: KE
authors.lastname: Knudsen
mesh_terms: D000726:Androgen Antagonists / Q000494:pharmacology; D002453:Cell Cycle; D049109:Cell Proliferation; D002470:Cell Survival; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism*; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015151:Immunoblotting; D008297:Male; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011944:Receptors, Androgen / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: C410798:AR protein, human; D000726:Androgen Antagonists; C530104:CCND1 protein, human; D012333:RNA, Messenger; D011944:Receptors, Androgen; D012097:Repressor Proteins; D019938:Cyclin D1; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4