Molecular Mechanism Of MiR-125b Mediated TSLC1 Regulation Of Proliferation,Invasion And Migration Of Bladder Cancer Cells

Objective: Bladder cancer(BC)is one of the most common malignancies of the genitourinary system,and its incidence rate ranks ninth among all tumors worldwide.It has a high recurrence rate and progressive clinical features,and it dose serious harm to human health.In recent years,the morbidity and mortality of bladder cancer in Chinese have been increasing year by year,and the incidence of bladder cancer ranks the first among urinary tract tumors of Chinese.Bladder cancer is divided into muscle invasive bladder cancer(MIBC)and non-muscle invasive bladder cancer(NMIBC).And the former is mainly treated by transurethral resection of bladder tumor(TURBT),while the latter is mainly treated by radical bladder cancer surgery.The recurrence rate of NMIBC patients is as high as 50-70%,and the prognosis is poor.The prognosis of MIBC patients is poor,and the recurrence rate,progression rate and long-term metastasis rate were all very high.Therefore,further study of the molecular mechanisms involved in the origin and development of bladder cancer,especially the tumor suppressor gene of bladder cancer,will help to find new therapeutic targets for the early diagnosis,effective treatment and prognosis of bladder cancer judgment,and provide new train of thought for researches,which are of great value for improving the prognosis of patients with bladder cancer.Tumor suppressor in lung cancer 1(TSLC1)is low expressed or deleted in a variety of tumor tissues or cell lines,such as lung cancer,prostate cancer,esophageal cancer,liver cancer,colon cancer,pancreatic cancer,melanoma,ovarian cancer,and breast cancer.And its low expression is closely related to the enhancement of invasion and migration of tumor cells.Up-regulation of TSLC1 expression can significantly inhibit the proliferation of tumor cells,promote the apoptosis of tumor cells,and reduce the invasion and migration of tumor cells.Micro RNA(miRNA)is an endogenous non-coding small RNA molecule with a length of 18-22 nucleotides.It inhibits the expression of the target gene by binding to the 3’-UTR of the target gene m RNA,degrading the m RNA or/and inhibiting the m RNA translation,and participates in the regulation of gene expression at the post-transcriptional level.Many studies have shown that miRNA is involved in the development of various tumors,including lung cancer,pancreaticcancer,breast cancer,thyroid cancer,colorectal cancer,liver cancer and leukemia.miR-125 b is low expressed or deleted in prostate cancer,ovarian cancer,breast cancer,thyroid cancer,oral cancer and bladder cancer.miR-125 b inhibits the biological behaviors of many tumors,such as lung cancer,pancreatic cancer,breast cancer,thyroid cancer,colorectal cancer,liver cancer and leukemia.However,the regulation of TSLC1 on bladder cancer cell proliferation,migration and invasion and whether miR-125 b mediates this regulation need further study.The purpose of this study was to investigate the regulation of miR-125 b expression by TSLC1,and to further explain its effect on the biological behaviors of bladder cancer cells,and to study the possible mechanism involved.Methods: Bladder urothelial carcinoma tissues and adjacent normal tissues were collected from a total of 50 patients who underwent surgical treatments in the Urology Department of the Second Hospital of Tianjin Medical University from September 2017 to July 2018.Western blot,quantitative RT-PCR and immunohistochemistry were used to detect the expression of TSLC1 and miR-125 b in bladder urothelial carcinoma tissues and normal tissues.Lentiviral miR-125 b low expression vector was constructed and transfected into bladder cancer T24 cells;then lentivirus TSLC1 overexpression vector was constructed to transfect the above cell lines.Quantitative RT-PCR was used to detect the expression of miR-125 b and TSLC1 m RNA in the above cell lines.Western blot was used to detect TSLC1 protein expression in the above cell lines.The effects of TSLC1 and miR-125 b on the proliferation,invasion and migration of bladder cancer T24 cells were evaluated using in vitro cell proliferation experiments,scratch experiments and Transwell experiments.Results:1.The expression levels of miR-125 b and TSLC1 in bladder cancer tissues were significantly lower than those in normal tissues.2.q RT-PCR results showed that the expression of miR-125 b in bladder cancer cell lines was significantly lower than that in the control group after transfection with the miR-125 b low expression vector,and the expression of TSLC1 was significantly higher than that in the control group.After transfection of TSLC1 overexpressionvector,TSLC1 expression was significantly higher than that of the control group,and miR-125 b expression was significantly higher than that of the control group.3.In vitro cell proliferation assay results showed that low expression of miR-125 b significantly promoted the proliferation of bladder cancer cells,while overexpression of TSLC1 significantly inhibited the proliferation of bladder cancer cells.4.Transwell assay and scratch assay results showed that low expression of miR-125 b significantly promoted the migration and invasion of bladder cancer cells,while overexpression of TSLC1 significantly inhibited the above-mentioned biological behaviors of bladder cancer cells.Conclusion: The study confirmed that TSLC1 acts as a tumor suppressor for bladder cancer by regulating miR-125 b in bladder cancer to inhibit bladder cancer cell proliferation,migration and invasion.Therefore,TSLC1 and miR-125 b provide new targets for the diagnosis,treatment and prognosis of bladder cancer.Conclusion: Our research initially verify that TSLC1 is involved in the regulation of miR-125 b expression at the molecular level.Overexpression of TSLC1 could inhibit the proliferation,migration and invasion of bladder cancer cells.Our research lays the foundation for the study of TSLC1 and miR-125 b as bladder cancer treatment targets,and it is expected to apply TSLC1 and miR-125 b in the clinical treatment of bladder cancer.