Anti-oncogenic effects of dutasteride, a dual 5-alpha reductase inhibitor and a drug for benign prostate hyperplasia, in bladder cancer

The incidence of bladder cancer (BCa) is approximately four times higher in men than in women. To develop effective BCa treatments, there is an urgent need to understand the differences in the BCa control mechanisms based on gender. Our recent clinical study showed that androgen suppression therapy using 5α-reductase inhibitors and androgen deprivation therapy affects BCa progression, but the underlying mechanisms are still unknown.

Dutasteride inhibited testosterone-induced BCa progression dependent on SLC39A9 in AR-negative BCa and repressed oncogenic signaling pathways, including those of metalloproteases, p21, BCL-2, NF-KB, and WNT. Our results also suggest that SRD5A1 plays a pro-oncogenic role in BCa. This work provides potential therapeutic targets for the treatment of BCa.

mRNA expression levels of the androgen receptor (AR) and SLC39A9 (membrane AR) in T24 and J82 BCa cells were evaluated by reverse transcription-PCR (RT-PCR). The effect of dutasteride, a 5α-reductase inhibitor, in BCa progression was determined in cells transfected with control and AR-overexpressing plasmids. In addition, cell viability and migration assays, RT-PCR, and western blot analysis were performed to analyze the effect of dutasteride on BCa in the presence of testosterone. Finally, steroidal 5α-reductase 1 (SRD5A1), one of the dutasteride target genes, was silenced in T24 and J82 BCa cells using control and shRNA-containing plasmids, and the oncogenic role of SRD5A1 was evaluated.

Dutasteride treatment led to significant inhibition of the testosterone-induced increase dependent on AR and SLC39A9 in cell viability and migration of T24 and J82 BCa cells and induced alterations in the expression level of cancer progression proteins, such as metalloproteases, p21, BCL-2, NF-KB, and WNT in AR-negative BCa. Furthermore, the bioinformatic analysis showed that mRNA expression levels of SRD5A1 were significantly higher in BCa tissues than in normal paired tissues. A positive correlation between SRD5A1 expression and poor patient survival was observed in patients with BCa. Also, Dutasteride treatment reduced cell proliferation and migration via blocking the SRD5A1 in BCa. Conclusions: Dutasteride inhibited testosterone-induced BCa progression dependent on SLC39A9 in AR-negative BCa and repressed oncogenic signaling pathways, including those of metalloproteases, p21, BCL-2, NF-KB, and WNT. Our results also suggest that SRD5A1 plays a pro-oncogenic role in BCa. This work provides potential therapeutic targets for the treatment of BCa.