The Study On The Mechanism Of Interaction Of MTOR And YAP1 Promotes Bladder Cancer Progression

Objective:Yes-associated protein 1(YAP1)and mTOR signaling were identified to be deregulated in bladder cancer and involved in its malignant progression.However,the crosstalk between YAP1 and mTOR in bladder cancer progression remains unclear.As a result,the present study aimed to explore it.Contents and methods:To detect the mRNA and protein levels of YAP1 and mTOR in bladder cancer and adjacent normal tissues;to detect the proliferation and apoptosis of HT-1376 and J82 bladder cancer cells after knockout of Yapl or mTOR gene;to detect the regulatory effect of mTOR on the expression of YAP1 in bladder cancer cells;to evaluate the effect of YAP1 on the activation of mTOR pathway in HT-1376 and J82 bladder cancer cells;to detect the location of mTOR and YAP1 protein;To explore the mechanism of YAP1 regulating mTOR ubiquitination.Results:Our results showed that YAP1 and mTOR were all elevated in bladder cancer tissues as compared to the adjacent normal tissues.Knockdown of either mTOR or YAP1 with siRNA transfection repressed the proliferation capacity and induced the apoptosis of bladder cancer HT-1376 cells and J82 cells,especially when YAP1 and mTOR were down-regulated simultaneously.Up-regulation of mTOR increased the mRNA and protein levels of YAP1,as well as enhanced its nuclear accumulation.Similarly,up-regulation of YAP1 increased mTOR expression and slowed down its protein degradation,while increased its ubiquitination.Besides,immunofluorescence and Duolink assays demonstrated that YAP1 and mTOR were co-located in nuclear.Immunoprecipitation(IP)assay showed that YAP1 protein could bind to mTOR protein.Moreover,YAP1 combined with SKP2,an E3 ubiquitin ligase,and knockdown of YAP1 reduced SKP2 expression.And the promotion of cell growth and inhibition of cell apoptosis induced by YAP1 over-expression were all abolished when SKP2 was down-regulated in HT-1376 cells and J82 cells,suggesting that YAP1 promoted the progression of bladder cancer through SKP1 induced mTOR up-regulation.Conclusion:our study indicates that the crosstalk between YAP1 and mTOR play a pivotal role in accelerating the progression of bladder cancer,which provides new insights of YAP1/mTOR axis on the occurrence and development of bladder cancer.