Abstract
Dysregulation of SUMO modification is linked to carcinogenesis. UBC9 is the sole conjugating enzyme in sumoylation and plays a pivotal role in maintaining homeostasis and restraining stress reactions. However, the clinical significance and function of UBC9 in bladder cancer remain unclear. In this study, immunohistochemistry was used to determine the expression of UBC9. UBC9 knock-down and SUMO inhibition were conducted followed by proliferation, migration, and cell cycle assays. RNA sequencing and bioinformatic analysis were used to identify potential mechanisms of UBC9. Cytokine membrane antibody array was used to detect the expression of cytokine. The mass cytometry TOF (CyTOF) was used to explore the association between bladder cancer stem cell-like population and UBC9 expression. Our results showed that UBC9 played a dual role in bladder cancer. UBC9 was up-regulated in bladder cancer, but was negatively correlated with TNM stage and grade. Knocking-down of UBC9 resulted in dramatic activation of inflammatory gene expression, which might cause inhibition of cell proliferation and inducing cell apoptosis. IL6 was the hub gene in UBC9 regulatory network. Markedly up-regulated IL6 after knocking-down of UBC9 activated the expression of CD44, which was a prominent marker of cancer stem cells. Thus, our results revealed an important and previously undescribed role for UBC9 in modulation of inflammatory signaling of bladder cancer. UBC9 in bladder cancer cells is required to maintain high sumoylation levels and alleviate stress-related inflammation threats to cell survival. Lacking UBC9 contributes to inflammation activation, epithelial-mesenchymal transition and stem cell-like population formation, leading to cancer progression.