Sequence-specific in vivo silencing of androgen receptor by low-dose naked siRNA inhibits prostate tumor growth.

DANIEL COMPAGNO, CAROLE MERLE, AURÉLIE MORIN, JACQUES MATHIEU, ALINE BOZEC, CLAIRE MAUDUIT, CRISTÈLE GILBERT, MOHAMMED BENAHMED AND FLORENCE CABON

Paris

Conferencia; ARTP meeting (15è); 2006

Background. Prostate carcinomas are initially dependent on androgens, and castration or androgen antagonists inhibit theirgrowth. After some time though, tumors become resistant and recur with a poor prognosis. The majority of resistant tumorsstill expresses a functional androgen receptor (AR), frequently amplified or mutated. Methodology/Principal Findings. To test the hypothesis that AR is not only expressed, but is still a key therapeutic target in advanced carcinomas, we injected siRNA targeting AR into mice bearing exponentially growing castration-resistant tumors. Quantification of siRNA into tumors and mouse tissues demonstrated their efficient uptake. This uptake silenced AR in the prostate, testes and tumors. AR silencing in tumors strongly inhibited their growth, and importantly, also markedly repressed the VEGF production and angiogenesis. Conclusions/Significance. Our results demonstrate that carcinomas resistant to hormonal manipulations still depend on the expression of the androgen receptor for their development in vivo. The siRNA-directed silencing of AR, which allows targeting overexpressed as well as mutated isoforms, triggers a strong antitumoral and antiangiogenic effect. siRNA-directed silencing of this key gene in advanced and resistant prostate tumors opens promising new therapeutic perspectives and tools.