Overexpression Of Indoleamine 2,3-Dioxygenase 1 Promotes Epithelial-Mesenchymal Transition By Activation Of The IL-6/STAT3/PD-L1 Pathway In Bladder Cancer

Objective Bladder cancer is one of the common malignant tumors of the urinary system cancer.It is the fourth most common cancer among men in the United States.The incidence and mortality of bladder cancer in China are also increasing year by year.Approximately75% of confirmed patients have non-muscle invasive bladder cancer(NMIBC),which has a higher recurrence rate,while 25% have muscle invasive bladder cancer(MIBC)with a poorer prognosis.However,the molecular mechanism of bladder cancer development has not been fully elucidated.At present,research on tumor metabolism and its genes has attracted more and more attention.Indoleamine 2,3-dioxygenase 1(IDO1)acts as a key enzyme that catalyzes the breakdown of tryptophan into kynurenine.High expression levels of IDO1 have been found in various human tumor tissues.Therefore,researchers believe that it plays an important role in the development of cancer.The molecular mechanism of IDO1 in bladder cancer has not been reported.The purpose of this study was to detect the expression of IDO1 in bladder cancer tissues,and to study the molecular mechanism of IDO1 in bladder cancer cells EMT.Methods The expression of IDO1 in bladder cancer tissues and cell lines was detected by bladder cancer tissue microarray,Real-time reverse transcription polymerase chain reaction(q RT-PCR),and Western Blot.And the relationship between the expression of IDO1 and the TNM staging,grading,recurrence and progression of bladder cancer was compared by clinical pathological data of bladder cancer tissue microarrays.In the cell line,lipofectamine 3000 transiently transfected Si-IDO1 and a negative control down-regulated the expression of IDO1.CCK-8 method,plate clone formation,Transwell assay and other methods to verify the effects of low expression of IDO1 on cell proliferation,migration,invasion and other biological behaviors,down-regulation of IDO1 on epithelial-mesenchymal transition by Western blooting assay(Epithelial-mesenchymal transition,EMT).And verify that IDO1 affects EMT through the IL6/STAT3/PD-L1 pathway.Results By immunohistochemistry,PCR confirmed that IDO1 expression was significantly higher in bladder cancer tissues than in adjacent tissues.Meanwhile,in bladder cancer cell lines(T24,UMUC3,EJ,3637),IDO1 expression was significantly higher than that of immortalized urothelium.Cell SV-HUC-1.And the expression of IDO1 in the TNM stage of fish bladder cancer was significantly negatively correlated(p<0.05).The proliferation,migration and invasion of bladder cancer were significantly inhibited after knocking down IDO1.EMT-related molecular markers N-cadherin and Vimentin were significantly decreased,while E-cadherin was significantly elevated.At the same time,knockdown of IDO1 also significantly decreased the expression of IL6,p-STAT3 and PD-L1,and when exogenously added to IL6,the STAT3 pathway inhibitor AG490,p-STAT3,PD-L1 and EMT related molecules were significantly Variety.Conclusion In summary,the data reveal that IDO1 significantly promotes the EMT process during bladder cancer development.Knockdown of IDO1 effectively targets cellular EMT by inhibiting the IL-6/STAT3/PD-L1 signaling pathway.Thus,inhibitors of IDO1 may become a new approach for the treatment of bladder cancer in the future.