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Background Males have a higher incidence of bladder cancer than females, but the reason remains unknown. Unlike prostate cancer, human bladder cancer is not generally considered to be dependent on hormone activity. We investigated the possible involvement of androgens and the androgen receptor (AR) in bladder cancer. Methods We used N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) to induce bladder cancer in wild-type male and female mice, with and without castration in males, and in AR knockout (ARKO) male and female mice, with and without dihydrotestosterone (DHT) supplementation in males. We also treated human bladder cancer cell lines, including TCC-SUP and UMUC3, and mouse xenograft models established from these same lines with androgen deprivation therapy (antiandrogen treatment or castration), AR-small-interfering RNA (AR-siRNA), or the anti-AR molecule ASC-J9, which causes selective degradation of the AR. Results More than 92% of wild-type male and 42% of wild-type female mice treated with BBN eventually developed bladder cancer, whereas none of the male or female ARKO mice did. Treatment with BBN induced bladder cancer in 25% of ARKO mice supplemented with DHT and in 50% of castrated wild-type male mice. Androgen deprivation of AR-positive human bladder cancer cells by androgen depletion in vitro or castration in mice and/or by treatment with the antiandrogen flutamide in vitro or in vivo, as well as AR knockdown by AR-siRNA or by ASC-J9, suppressed cell proliferation in vitro and xenograft tumor growth in vivo. Conclusions Our findings implicate the involvement of both androgens and the AR in bladder cancer. Targeting AR and androgens may provide novel chemopreventive and therapeutic approaches for bladder cancer. [ABSTRACT FROM AUTHOR]

Testicular orphan nuclear receptor 4 (TR4) is specifically and stage-dependently expressed in late-stage pachytene spermatocytes and round spermatids. In the developing mouse testis, the highest expression of TR4 can be detected at postnatal days 16 to 21 when the first wave of spermatogenesis progresses to late meiotic prophase. Using a knockout strategy to delete TR4 in mice, we found that sperm production in TR4-/- mice is reduced. The comparison of testes from developing TR4+/+ and TR4-/- mice shows that spermatogenesis in TR4-/- mice is delayed. Analysis of the first wave of spermatogenesis shows that the delay can be due to delay and disruption of spermatogenesis at the end of late meiotic prophase and subsequent meiotic divisions. Seminiferous tubule staging shows that stages X to XII, where late meiotic prophase and meiotic divisions take place, are delayed and disrupted in TR4-/- mice. Histological examination of testis sections from TR4-/- mice shows degenerated primary spermatocytes and some necrotic tubules. Testis-specific gene analyses show that the expression of sperm I and cyclin A1, which are genes expressed at the end of meiotic prophase, was delayed and decreased in TR4-/- mouse testes. Taken together, results from TR4+/+ and TR4-/- mice indicate that TR4 is essential for normal spermatogenesis in mice. [ABSTRACT FROM AUTHOR]