Intraprostatic Androgens and Androgen-Regulated Gene Expression Persist Following Testosterone Suppression

ABSTRACT: Introduction: Androgen deprivation therapy (ADT) remains the primary treatment for advanced prostate cancer (PCa). The efficacy of ADT has not been rigorously evaluated by demonstrating suppression of prostatic androgen activity at the target tissue and molecular level. We determined the efficacy and consistency of medical castration in suppressing prostatic androgen levels and androgen-regulated gene-expression. Design: Androgen levels and androgen-regulated gene-expression (by microarray-profiling, qRT-PCR and immunohistochemistry) were measured in prostate samples from a clinical trial of short-term castration (1 month) using the GnRH-antagonist, Acyline, vs. placebo in healthy men. To assess the effects of long-term ADT, gene-expression measurements were evaluated at baseline and after 3, 6 and 9 months of neoadjuvant ADT in prostatectomy samples from men with localized PCa. Results: Medical castration reduced tissue androgens by 75% and reduced the expression of several androgen-regulated genes (NDRG1, FKBP5, TMPRSS2). However, many androgen-responsive genes, including the androgen receptor (AR) and PSA, were not suppressed after short-term castration, nor after 9 months of neoadjuvant ADT. Significant heterogeneity in PSA and AR protein expression was observed in PCa samples at each time-point of ADT. Conclusions: Medical castration based on serum testosterone levels cannot be equated with androgen ablation in the prostate microenvironment. Standard androgen deprivation does not consistently suppress androgen-dependent gene-expression. Suboptimal suppression of tumoral androgen activity may lead to adaptive cellular changes allowing PCa cell survival in a low androgen environment. Optimal clinical efficacy will require testing of novel approaches targeting complete suppression of systemic and intracrine contributions to the prostatic androgen microenvironment. Keywords: prostate, androgen, Acyline, microarray, immunohistochemistry

ORGANISM(S): Homo sapiens

PROVIDER: GSE8466 | GEO | 2007/10/25

SECONDARY ACCESSION(S): PRJNA101551

REPOSITORIES: GEO