Effects of Androgen and Estrogen Receptor Signaling Pathways on Bladder Cancer Initiation and Progression

Epidemiologic studies have long demonstrated clear differences in incidence and progression of bladder cancer between genders suggesting that the mechanisms of development and progression in these tumors have a strong association with steroid hormonal pathways. Such observations led to preclinical studies investigating the role of androgen and estrogen receptors, as well as their cognate hormones in bladder cancer initiation and progression. Using various in vitro cell line assays and in vivo mouse models, studies have elucidated different mechanisms and signaling pathways through which these steroid receptors may participate in this disease. More recently, RNA expression data from multiple studies revealed a luminal subtype of bladder cancer that exhibited an estrogen receptor signaling pathway, making it a strong candidate for further consideration of targeted therapies in the future. Despite the promising preclinical data demonstrating potential roles for both antiandrogen and antiestrogen strategies targeting these pathways in different stages of bladder cancer, only two clinical trials are currently active and accruing patients for such clinical studies. Targeted therapies in bladder cancer are a large unmet need and have the potential to change treatment paradigms and improve oncological outcomes of patients with bladder cancer.