MicroRNA-186-5p Inhibits Cell Proliferation,Migration And Invasion In Bladder Cancer By Targeted Silencing Of RAB27A/B Gene

Background:Bladder Cancer(BCa)is the most common malignant tumor in the urinary system,with a high incidence rate and mortality rate.Several studies have shown that miR-186-5p,RAB27A and RAB27B play key roles in many malignancies,but there are few reports on the role of miR-186-5p and RAB27A/B genes in bladder cancer.Bladder cancer has been a difficult problem in clinical treatment,and sensitive and specific early diagnostic markers are still lacking.Therefore,looking for reliable and sensitive targeted genes in the molecular targeted therapy of bladder cancer and exploring the mechanism of bladder cancer has a relatively broad application prospect.Objective:To investigate the expression of RAB27A and RAB27B in bladder cancer and their correlation with clinical features and prognosis,to investigate their effects on the biological functions of bladder cancer cells,and to investigate how miR-186-5p can regulate RAB27A/B and inactivate the PI3K/MAPK signaling pathway by targeting them to affect the biological behaviors of bladder cancer.Methods:The expression of RAB27A and RAB27B in bladder cancer tissues and cells was assessed by immunohistochemistry and quantitative polymerase chain reaction(qPCR),Western blot(WB),and clinical data were combined to analyze the correlation between the expression of RAB27A and RAB27B and their clinicopathology.RAB27A/B siRNA transfection into BCA cell lines was used to downregulate RAB27A/B expression,and CCK8,cell scratch and Transwell chamber assays were used to determine the cell proliferation,migration and invasion abilities,and RTq-PCR and WB assays were performed to determine the expression of epithelial mesenchymal transition(EMT)-related proteins,Ecadherin and Vimentin.MiRNAs binding to RAB27A/B were predicted by bioinformatics software Starbase and miRDB and validated using overexpression experiments and luciferase experiments.CCK8 assay,cell scratch,Transwell chamber,and WB assays were performed to test whether overexpression of RAB27A/B could reverse the process of proliferation,migration,invasion,and suppression of EMT caused by miR-186-5p overexpression in BCa cells and the inactivation of key proteins in the PI3K/MAPK signaling pathway.Xenograft nude mice animal models were established to explore the mechanism of miR-186-5p in vivo.Results:RAB27A/B were significantly highly expressed in bladder cancer tissues and cell lines.The factors associated with the expression differences of RAB27A and RAB27B were pathological grade,clinical stage and tumor type,and high expression of RAB27A and RAB27B was a single independent prognostic factor for BCa.Silencing RAB27A/B inhibited BCa cell proliferation,migration and invasion,as well as the epithelial mesenchymal transition(EMT)process.miR-186-5p is an upstream acting miRNA of RAB27A/B in BCa,miR-186-5p expression is significantly downregulated in BCa cells and tissues,and miR-186-5p directly targets the 3’-untranslated region(3’-UTR)of RAB27A/B and downregulates the mRNA and protein levels of RAB27A/B in BCa cells.miR-186-5p overexpression suppressed BCa cell proliferation,migration and invasion as well as EMT processes in vitro and suppressed tumor growth in vivo,and overexpression of RAB27A/B reversed the suppressive effect of miR-186-5p overexpression on the malignant phenotype of BCa cells.miR-186-5p inactivates the PI3K/MAPK signaling pathway by downregulating RAB27A/B expression.Conclusions:RAB27A/B is overexpressed in bladder cancer tissues and cell lines,and the level of RAB27A/B expression is associated with the clinical and prognosis of bladder cancer patients,and RAB27A/B significantly promotes BCa cell proliferation,migration,invasion and EMT.miR-186-5p was lowly expressed in bladder cancer and inhibited the proliferation,migration,invasion and EMT process of BCa cells in vivo and in vitro by down regulating RAB27A/B expression and inactivating the PI3K/MAPK signaling pathway.Our study is important for exploring the function of RAB27A/B in bladder cancer development and progression,and this study may provide new insights into understanding the mechanism of miR-186-5p and RAB27A/B genes in BCa.