Conclusion
Our results provide new insight into the mechanisms underlying intrinsic apoptosis in BC, suggesting that the miR-183-5p-PNPT1 regulatory axis regulates the apoptosis of BC cells and might represent a potential therapeutic avenue for the treatment of BC.
Methods
The upstream miRNA regulators were predicted by in silico analysis. The expression levels of PNPT1 were evaluated by real-time PCR, Western blotting, and immunohistochemistry (IHC), while miR-183-5p levels were evaluated by qPCR in BC cell lines and tissues. In vitro and in vivo assays were performed to investigate the function of miR-183-5p and PNPT1 in apoptotic RNA decay and the tumorigenic capability of bladder cancer cells.
Objective
It has been reported that intrinsic apoptosis is associated with the progression of bladder cancer (BC). Recent evidence suggests that polyribonucleotide nucleotidyltransferase 1 (PNPT1) is a pivotal mediator involved in RNA decay and cell apoptosis. However, the regulation and roles of PNPT1 in bladder cancer remain largely unclear.
Results
PNPT1 expression was decreased in BC tissues and cell lines. Overexpression of PNPT1 significantly promoted cisplatin-induced intrinsic apoptosis of BC cells, whereas depletion of PNPT1 potently alleviated these effects. Moreover, oncogenic miR-183-5p directly targeted the 3' UTR of PNPT1 and reversed the tumor suppressive role of PNPT1. Intriguingly, miR-183-5p modulated not only PNPT1 but also Bcl2 modifying factor (BMF) to inhibit the mitochondrial outer membrane permeabilization (MOMP) in BC cells.