Androgen and Wnt signaling in bladder cancer

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ABSTRACT Bladder cancer is the 4th most common cancer in men and 11th in women. Despite that bladder development and function are not sex hormone-dependent, men are three times more likely to develop bladder cancer than women. Smoking has been shown not to be a contributor for this gender bias. Instead, intrinsic sex-differences likely underpin the molecular mechanism for male susceptibility to bladder cancer. Sex hormones and sex chromosomes are obvious suspects to account for this male predilection for bladder cancer. In fact, experimental evidence in rodents strongly support a crucial role for androgen receptor in promoting cancer development in a chemical-induced bladder cancer model. In addition to androgen signaling, the other undeniably powerful regulator of lower urinary tract development and carcinogenesis is the WNT signaling pathway. β-catenin is the signal integrator of canonical WNT signaling and AR and β-catenin physically interact to synergistically activate transcription. This interaction is crucial for downstream target expression during genital masculinization, bladder cancer development and progression. Despite the crucial roles these two pathways play in bladder carcinogenesis, their direct transcriptional targets, which are likely drivers of bladder cancer initiation, remain elusive. In this application, we propose to use a recently developed powerful technology, Split DamID to reveal in vivo transcriptional targets downstream of AR, p300 and β-catenin during bladder cancer development. In Aim 1, we will use our newly generated transgenic model to reveal direct AR and p300 transcriptional targets in a carcinogen-induced bladder cancer model. Next, in Aim 2, we will use SpDamID on bladder organoids to reveal AR and β-catenin direct targets, followed by siRNA functional screen for their roles in promoting organoid formation. Together, these studies should greatly improve our understanding of bladder cancer initiation, especially those controlled by AR and Wnt signaling.