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Modeling lethal prostate cancer variant with small cell carcinoma features [genomic profile]

ABSTRACT: Purpose: Small-cell prostate carcinoma (SCPC) morphology predicts for a distinct clinical behavior, resistance to androgen ablation, and frequent but short responses to chemotherapy. The model systems we report reflect the biology of the human disease and can be used to improve our understanding of SCPC and to develop new therapeutic strategies for it. Experimental Design: We developed a set of CRPC xenografts and examined their fidelity to their human tumors of origin. We compared the expression and genomic profiles of SCPC and large cell neuroendocrine carcinoma (LCNEC) xenografts to those of typical prostate adenocarcinoma xenografts and used a panel of 60 human tumors to validate our findings using immunohistochemistry. Results: We show that SCPC and LCNEC xenograft models retain high fidelity to their human tumors of origin and are characterized by a marked upregulation of UBE2C and other M-phase cell cycle genes in the absence of AR, retinoblastoma (RB1) and cyclin D1 (CCND1) expression and confirm these findings in a panel of CRPC patients’ samples. In addition, array comparative genomic hybridization of the xenografts showed that the SCPC/LCNEC tumors display more copy number variations than the adenocarcinoma counterparts and that there is amplification of the UBE2C locus and microdeletions of RB1 in a subset of these, but no AR nor CCND1 deletions. Moreover, the AR, RB1, and CCND1 promoters showed no CpG methylation in the SCPC xenografts. Conclusion: Modeling human prostate cancer with xenografts allows in-depth and detailed studies of its underlying biology. The detailed clinical annotation of the donor tumors enables associations of anticipated relevance to be made. Futures studies in the xenografts will address the functional significance of the findings.

ORGANISM(S): Homo sapiens

PROVIDER: GSE33053 | GEO | 2012/01/01

SECONDARY ACCESSION(S): PRJNA156569

REPOSITORIES: GEO

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Project description:Purpose: Small-cell prostate carcinoma (SCPC) morphology predicts for a distinct clinical behavior, resistance to androgen ablation, and frequent but short responses to chemotherapy. The model systems we report reflect the biology of the human disease and can be used to improve our understanding of SCPC and to develop new therapeutic strategies for it. Experimental Design: We developed a set of CRPC xenografts and examined their fidelity to their human tumors of origin. We compared the expression and genomic profiles of SCPC and large cell neuroendocrine carcinoma (LCNEC) xenografts to those of typical prostate adenocarcinoma xenografts and used a panel of 60 human tumors to validate our findings using immunohistochemistry. Results: We show that SCPC and LCNEC xenograft models retain high fidelity to their human tumors of origin and are characterized by a marked upregulation of UBE2C and other M-phase cell cycle genes in the absence of AR, retinoblastoma (RB1) and cyclin D1 (CCND1) expression and confirm these findings in a panel of CRPC patients’ samples. In addition, array comparative genomic hybridization of the xenografts showed that the SCPC/LCNEC tumors display more copy number variations than the adenocarcinoma counterparts and that there is amplification of the UBE2C locus and microdeletions of RB1 in a subset of these, but no AR nor CCND1 deletions. Moreover, the AR, RB1, and CCND1 promoters showed no CpG methylation in the SCPC xenografts. Conclusion: Modeling human prostate cancer with xenografts allows in-depth and detailed studies of its underlying biology. The detailed clinical annotation of the donor tumors enables associations of anticipated relevance to be made. Futures studies in the xenografts will address the functional significance of the findings. 22 samples were analysed, that included MDA PCa 79 (n = 3), 117-9 (n = 3), 130 (n = 2), 144-4 (n = 4), 144-13 (n = 5), 146-10 (n = 3), 155-2 (n = 1), and 155-12 (n = 1). MDA PCA 79, 117-9 and 130 samples had the pathologic characteristics of prostate adenocarcinoma and were compared against MDA PCA 144-4, 144-13, 146-10 and 155-12 that have the pathologic features of prostate small cell/ large cell neuroendocrine carcinoma

Project description:Continued androgen receptor (AR) signaling is an established mechanism underlying castration-resistant prostate cancer (CRPC), and suppression of AR signaling remains a therapeutic goal of CRPC therapy. Constitutively active androgen receptor splicing variants (AR-Vs) lack the AR ligand-binding domain (AR-LBD), the intended target of androgen deprivation therapies (ADT) including new CRPC therapies such as abiraterone and MDV3100. While the canonical full-length AR (AR-FL) and AR-Vs are both increased in CRPC, their expression regulation, associated transcriptional programs, functional relationships, and respective roles in mediating responses to endocrine therapies have not been dissected. In this study, we show that suppression of canonical AR-FL signaling by targeting AR-LBD leads to increased AR-V expression in two cell line models of CRPC. Importantly, treatment-induced AR-Vs activate a distinct expression signature enriched for cell cycle genes without requiring the presence of AR-FL. Conversely, activation of AR-FL signaling suppresses the AR-V signature but activates expression programs mainly associated with macromolecular synthesis, metabolism, and differentiation. In prostate cancer cells and CRPC xenografts treated with MDV3100 and abiraterone, increased expression of two constitutively active AR-Vs, AR-V7 and ARV567ES, but not AR-FL, parallels increased expression of the AR-driven cell cycle gene UBE2C. In addition, protein expression of AR-V7, but not AR-FL, is positively correlated with UBE2C in clinical CRPC specimens. The cumulative in vitro and in vivo evidence support an adaptive shift toward AR-V-mediated signaling in at least a subset of CRPC tumors as the AR-LBD is rendered inactive, suggesting an important mechanism contributing to drug resistance to CRPC therapies. LNCaP cells lacking AR-V were transfected with AR-V7 with or without androgen stimulation of AR-FL (4 conditions); LNCaP95 cells expressing AR-Vs were treated with control siRNA or siRNA trageting AR-LBD or AR-DBD, with or without androgen stimulation of AR-FL (6 conditions); VCaP cells expressing AR-Vs in the presence of androgen were treated with control siRNA, siRNA trageting AR-LBD, DMSO or MDV3100 to inhibit AR-FL (4 conditions). Total 14 arrays with no replicates.

Project description:Enzalutamide (ENZ) is a potent androgen receptor (AR) antagonist with activity in castration-resistant prostate cancer (CRPC); however, progression to ENZ-resistant (ENZ-R) CRPC frequently occurs with rising serum PSA levels, implicating AR full length (ARFL) or variants (AR-Vs) in disease progression. To define functional roles of ARFL and AR-Vs in ENZ-R CRPC, we designed 3 antisense oligonucleotides (ASO) targeting exon 1, intron 1, and exon 8 in AR pre-mRNA to knockdown either ARFL alone, or ARFL plus AR-Vs, and examined their respective effects in LNCaP-derived ENZ-R, as well as M12 and 22Rv1, cells. ENZ-R LNCaP xenografts express high levels of both ARFL and AR-V7 compared to CRPC LNCaP xenografts. In particular, ARFL levels were ~20-fold higher than AR-V7. ENZ-R LNCaP sub-lines, derived by selection from the ENZ xenografts, also expressed uniformly high levels of ARFL and AR-V7 compared to CRPC LNCaP cells. In addition, both ARFL and AR-V7 are highly expressed in the nuclear fractions of ENZ-R-LNCaP. In ENZ-R LNCaP cells, knockdown of ARFL alone, or ARFL plus AR-Vs, similarly induced apoptosis, suppressed cell growth and AR-regulated gene expression in vitro, and delayed tumour growth in vivo. In 22Rv1 cells that are inherently resistant to ENZ, knockdown of both ARFL and AR-Vs more potently suppressed cell growth, AR transcriptional activity and AR-regulated gene expression than knockdown of ARFL alone. These data indicate the AR is an important driver of ENZ resistance, and while the contributions of ARFL and AR-Vs can vary across cell systems, ARFL is the key driver in the ENZ-R LNCaP model. AR targeting strategies against both ARFL and AR-Vs is a rational approach for AR-dependent CRPC. CRPC and ENZ-R LNCaP xenografts were generated as described in: Gleave, M.E., et al., Serum prostate specific antigen levels in mice bearing human prostate LNCaP tumors are determined by tumor volume and endocrine and growth factors. Cancer Res, 1992. 52(6): p. 1598-605.

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Modeling lethal prostate cancer variant with small cell carcinoma features [genomic profile]

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