TP53INP2 Modulates Epithelial-to-Mesenchymal Transition via the GSK-3β/β-Catenin/Snail 1 Pathway in Bladder Cancer Cells

Background: The tumor protein p53-inducible nuclear protein 2 (TP53INP2), an autophagy protein, is essential for autophagosome formation. The deregulation of autophagy is associated with multiple human diseases, including cancer. The present study aims to explore the role of TP53INP2 in bladder cancer. Materials and Methods: Quantitative real-time polymerase chain reaction was used to detect the mRNA level. Relative TP53INP2 protein expression was detected by immunohistochemistry and Western blot. The effect of TP53INP2 silencing on the proliferation, migration, and invasion of bladder cancer cells was investigated by CCK-8 detection kit and transwell assay. In addition, transfection and immunofluorescence were performed. Results: In this study, we report that high expression of TP53INP2 is correlated with poor patient survival in bladder cancer. Results demonstrate that the depletion of TP53INP2 inhibits the migration, invasion, and epithelial-to-mesenchymal transition (EMT) of bladder cancer cells. The underlying mechanism was explored. Results show that the TP53INP2 knockdown suppresses EMT by inhibiting the active non-phosphorylated beta-catenin and decreasing the Snail1 levels. Furthermore, the glycogen synthase kinase-3 beta (GSK-3 beta) inhibitor IM-12 abrogates the effect of TP53INP2 silencing. Interestingly, the induction of autophagy partially abrogates the TP53INP2 knockdown-induced decrease in active beta-catenin and inhibition of migration and invasion in bladder cancer cells. Conclusion: In summary, our results show that the downregulation of TP53INP2 inhibits EMT via the GSK-3 beta/beta-catenin/Snail1 pathway in bladder cancer. The findings of this study uncover the novel role of TP53INP2 and offer new insights into bladder cancer clinical therapy.