Evaluation of androgen receptor and androgen receptor splice-variant 7 in bladder cancer; a novel approach into an ancient topic.

PURPOSE

The contribution of androgen receptors (AR) on bladder cancer has been demonstrated in pre-clinical studies, however in clinical studies, only the canonical AR (AR-FL) protein was measured by immunohistochemistry and conflicting results were obtained. To get better insight into the alterations of AR signalling, we used western blotting (WB) method and simultaneously measured both mRNA and protein levels of AR-FL and AR-V7.

METHODS

23 naive non-muscle invasive bladder cancer patients and 12 healthy individuals were included. AR-FL protein, AR-FL mRNA, AR-V7 protein and AR-V7 mRNA levels were quantitatively measured by WB and qRT-PCR.

RESULTS

While AR-FL protein and AR-V7 mRNA were significantly higher in bladder cancer, AR-FL mRNA and AR-V7 protein were lower. AR-V7 mRNA level was higher in patients with tumour size over 3 cm and AR-FL protein was higher in single tumours (p < 0,005). The small sampling size and the inclusion of only male participants were the main limitations.

CONCLUSIONS

The increase of AR-FL protein in bladder cancer supports the contribution of the AR pathway in bladder cancer. The presence of high AR-FL protein despite low mRNA levels may be due to a disruption in post-transcriptional regulatory mechanisms. AR-V7 was demonstrated for the first time in bladder tissue and found significantly different in bladder cancer tissues. Our study reached new and valuable findings and will shed light on the studies that aim to clarify the role of the AR pathway in bladder cancer.