Combination of androgen receptor inhibitor and cisplatin, an effective treatment strategy for urothelial carcinoma of the bladder.

Purpose: The role of androgen receptor (AR) signaling in bladder cancer (BCa) is not fully characterized. This study aimed to delineate the role of AR signaling in BCa and to determine whether the combination of AR inhibitor, Enzalutamide (Enz), and Cisplatin (Cis) efficiently inhibit the growth of BCa cells.

Methods: AR expression was determined in 89 human urothelial BCa specimens by immunohistochemistry. A panel of BCa cell lines was treated with Cis, Enz, or a combination of both (Enz + Cis). We determined the expression of AR, changes in apoptotic signaling, DNA damage, and analyzed effect on epithelial mesenchymal transformation markers.

Result: AR expression was detected in 61.4% of tumors from male BCa patients. Inhibition of AR signaling by Enz effectively inhibited the growth of AR BCa cells by inducing apoptosis (26%) in AR TCCSUP (P = 0.0201) and J82 (15%, P = 0.0386) cells. Interestingly, Enz + Cis synergistically inhibited the proliferation of BCa cells even at low concentrations by inducing proapoptotic signaling in AR BCa cells. Invasive and migratory potential of TCCSUP and J82 cells were reduced with Enz + Cis treatment, and associated with down-regulation of mesenchymal markers.

Conclusions: A high percentage of the bladder tumors from male patients in our cohort expressed AR. The combination of Enz and Cis synergistically inhibited growth of BCa cells more efficiently than single agent alone. This supports the rationale for future investigation of AR antagonists in combination with standard chemotherapy in MIBC.