Molecular and immunohistochemical evaluation of BAP-1 antibody in bladder cancer and comparison with luminal-basal subtyping

Aim: Molecular subtyping has become increasingly important in bladder cancer, and it is mainly divided into "luminal" and "basal" types. Despite the large amount of studies about the molecular pathway of bladder cancer, there are few studies about BAP-1. The aim of this study is to evaluate the BAP-1 expression molecularly and immunohistochemically and compare it with GATA-3 and CK5/6 immunohistochemical stains. Materials and method: A BAP-1 antibody was applied by western blotting to the tumor and normal tissues of 11 patients with known primary bladder tumors. The paraffin blocks of 150 non-invasive and 150 invasive tumor tissues were selected from transurethral resection materials. BAP-1, GATA-3, and CK5/6 immunohistochemical stains were applied to them, and the results were evaluated. Results: The protein expression levels of BAP-1 increased more in the tumor tissues compared to the normal tissues. The immunohistochemical BAP-1 expression was strong in the muscle-invasive group. The immunohistochemical GATA-3 expression was higher in the non-invasive group, and the CK5/6 expression was higher in the muscle-invasive group. The GATA-3 and CK5/6 immunohistochemical stains had a negative correlation in the muscle-invasive group. The immunohistochemical expression of BAP-1 had no correlation with GATA-3 and CK5/6 in all groups. Conclusions: Molecular subtyping has become increasingly important in bladder cancer and it is mainly divided into "luminal" and "basal" type. Despite the large amount of studies about molecular pathway of the bladder cancer, there are a few studies about BAP-1. The aim of this study is to evaluate the BAP-1 expression molecularly and immunohistochemically and compare it with GATA-3 and CK5/6 immunohistochemical stains.