1. Department of Urology, Xiangya Hospital, Central South University, Changsha, China.
2. Department of Pathology, Xiangya Hospital, Central South University, Changsha, China.
3. Department of Neurosurgery, Sanbo Brain Hospital, Beijing, China.
Although intravesical gemcitabine (GEM) chemotherapy (IGC) can effectively reduce the recurrence risk of non-muscle invasive bladder cancer (NMIBC), the development of GEM resistance may occur and result in cancer recurrence and disease progression. Herein, a label-free proteomics approach was used to characterize the proteomic profiles of primary/post-IGC recurrent NMIBC. A total of 218 proteins were found to be differentially expressed in paired primary and post-IGC recurrent NMIBC. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that multiple signaling pathways including “focal adhesion” were highly enriched in recurrent NMIBC. Niban apoptosis regulator 1 (NIBAN1) was identified as the top upregulated protein in recurrent NMIBC. Highly increased NIBAN1 expression was observed in a number of GEM-resistant cancer cell lines and in post-IGC recurrent NMIBC specimens. Manipulation of NIBAN1 expression affected the chemosensitivity to GEM in bladder cancer cell models. Moreover, NIBAN1 also regulated focal adhesion/focal adhesion kinase (FAK) signaling activation in bladder cancer cell lines. Highly elevated FAK (pY397) expression was observed in post-IGC recurrent NMIBC specimens, which was positively correlated with NIBAN1 expression. Knockdown of FAK markedly attenuated GEM resistance in GEM-resistant bladder cancer cells. In vivo studies demonstrated that knockdown of NIBAN1 disrupted FAK signaling and sensitized GEM-resistant bladder cancer cells to GEM treatment. Our findings suggest that NIBAN1 might regulate FAK signaling activation to promote GEM resistance in bladder cancer. Targeting NIBAN1/FAK signaling may help sensitize bladder cancer cells to GEM treatment.
Keywords: bladder cancer, NIBAN1, FAK, gemcitabine, chemoresistance