Project description:Constitutively active AR variants are truncated proteins lacking the c-terminal region containing the ligand binding domain (LBD) and the activation function 2 (AF-2). The expression of these AR variants in CRPC was also associated with the resistance to novel therapies such as enzalutamide and abiraterone acetate. These variants are also involved in tumor progression.
Project description:Background. Androgen receptor splice variant-7 (AR-V7) is a truncated form of the androgen receptor protein which lacks the ligand-binding domain, the target of enzalutamide and abiraterone, but remains constitutively active as a transcription factor. We hypothesized that detection of AR-V7 in circulating tumor cells (CTCs) from men with advanced prostate cancer would be associated with resistance to enzalutamide and abiraterone. Methods. We used quantitative reverse-transcription polymerase-chain-reaction (qRT-PCR) to interrogate CTCs for the presence or absence of AR-V7 from prospectively enrolled patients with metastatic castration-resistant prostate cancer initiating treatment with either enzalutamide or abiraterone. We examined associations between AR-V7 status and PSA response rates, PSA-progression-free-survival (PSA-PFS), clinical/radiographic-progression-free-survival (PFS), and overall survival (OS). Multivariable Cox regression analyses were performed to determine the independent effect of AR-V7 status on clinical outcomes. Results. Thirty-one enzalutamide-treated patients and thirty-one abiraterone-treated patients were enrolled, of which 38.7% and 19.4% had detectable AR-V7 from CTCs, respectively. Among men receiving enzalutamide, AR-V7–positive patients had inferior PSA response rates (0% vs 52.6%, P=0.004), PSA-PFS (median: 1.4 vs 6.0 months, P<0.001), PFS (median: 2.1 vs 6.1 months, P<0.001), and OS (median: 5.5 months vs not reached, P=0.002) compared to AR-V7–negative patients. Similarly, among men receiving abiraterone, AR-V7–positive patients had inferior PSA response rates (0% vs 68.0%, P=0.004), PSA-PFS (median: 1.3 months vs not reached, P<0.001), PFS (median: 2.3 months vs not reached, P<0.001), and OS (median: 10.6 months vs not reached, P=0.006). The negative prognostic impact of AR-V7 was maintained after adjusting for full-length-AR expression. Conclusions. Detection of AR-V7 in CTCs from patients with castration-resistant prostate cancer is associated with resistance to enzalutamide and abiraterone. A total of four metastatic castration-resistant prostate tumor samples from four patients were subjected to RNA-seq. Two samples were positive for androgen receptor splice variant 7 and the other two were negative for this variant.
Project description:Constitutively active AR variants are truncated proteins lacking the c-terminal region containing the ligand binding domain (LBD) and the activation function 2 (AF-2). The expression of these AR variants in CRPC was also associated with the resistance to novel therapies such as enzalutamide and abiraterone acetate. These variants are also involved in tumor progression.
Project description:The goal of this study was to determine the effects of a well-characterized anti-androgen, abiraterone acetate, and a suspected human anti-androgen, di-n-butyl phthalate (DBP) on the androgenic function of human fetal testis. Human fetal testis was xenografted into the renal subcapsular space of castrated male athymic nude mice. Hosts were treated with hCG to stimulate testosterone production in the xenografts, and were concurrently treated with either abiraterone acetate or DBP. While abiraterone acetate (14 d, 75 mg/kg/d p.o.) dramatically reduced testosterone and the weights of androgen-sensitive host organs, DBP (14 d, 500 mg/kg/d p.o.) had no effect on androgenic endpoints. Three paired analyses were performed using the LIMMA package in R (commands lmfit and eBayes), with the Benjamini-Hochberg correction for multiple comparisons (Smyth 2005): vehicle-treated xenografts vs. unimplanted testis (n=5), abiraterone-treated xenografts vs. matched control xenografts (n=3), and DBP-treated xenografts vs. matched control xenografts (n=3). There were significant differences in gene expression between grafted and ungrafted samples, including dramatic upregulation of microRNAs. Gene expression analysis also showed that abiraterone decreased expression of genes related to cell differentiation, while DBP induced expression of oxidative stress response genes and decreased expression of factors related to embryonic development. 17 xenograft samples were analyzed, including 5 unimplanted samples, 6 vehicle treated xenografts, 3 abiraterone acetate-treated xenografts, and 3 DBP-treated xenografts. Samples were paired (derived from the same donor tissue) for each comparison: vehicle vs. unimplanted (n=5), abiraterone vs. vehicle (n=3), and DBP vs. vehicle (n=3).
Project description:To identify the molecular signature associated with abiraterone acetate (AA) response and mechanisms underlying AA resistance in castration-resistant prostate cancer patient-derived xenografts (PDXs).
Project description:We report RNA sequencing data on serial biopsies of prostate cancer VCaP xenografts as the tumors pass from androgen-sensitivity (Pre-Cx), to castration resistance (CRPC, castration resistant prostate cancer), onto resistance to dual therapy with abiraterone plus enzalutamide (AER). From comparison of these RNAseq data sets, we were able to determine differentially expressed genes between the AER/CRPC and Pre-Cx states that could mediate resistance to androgen deprivation therapies.