| Bladder cancer,the most common malignant tumor of the urinary system,is one of the most important problems that endanger the health of human beings.The incidence of bladder cancer ranks 10th among all malignancies in the world.According to global statistics,there are an estimated 549,000 new cases and 200,000 deaths in 2018.The incidence of men is about three times that of women.In 2019,approximately 80,470patients(61,700 males)were diagnosed with bladder cancer,and 17,670(12,870 males)died of bladder cancer in the United States.Its morbidity ranks fourth among male malignancies and its mortality ranks first Eight.Compared to European and American countries,the incidence of bladder cancer in China is relatively low.However,in recent years,with the aging of society,the enrichment of people's lifestyles,the discovery of many new biomarkers,and the development of imaging technology,the incidence and detection rate of bladder cancer in China has increased significantly.The majority of bladder cancers are urothelial carcinomas,which have complex tumor biological behaviors,diverse genetic subtypes,and are prone to recurrence and metastasis,causing difficulties in current clinical diagnosis and treatment.Therefore,finding new targets for diagnosis and treatment through in-depth study of molecular mechanisms has become a hotspot in bladder cancer research.m~6A,the modification first identified in m RNA-enriched RNA fractions in 1974,refers to methylation of the N6 position of adenosine base widely distributed in the mammalian m RNA.With the application of available methods for detecting m~6A,the insights of regulation mechanism have been revealed in recent years.m~6A RNA modification is a dynamic and reversible posttranscriptional modification process maintained by multicomponent methyltransferase‘writer'complex(METTL3,METTL14 and their cofactors as WTAP,etc.)and removed by demethylase‘eraser'(FTO and ALKBH5).The function of m~6A in m RNA metabolism alters primarily depending on the reader proteins,including YT521-B homology(YTH)domain family(YTHDF1-3,YTHDC1-2)and IGF2 m RNA binding proteins family.Studies documenting the importance of m~6A modification in physiological bioprocess and pathogenesis of diseases emerged in large numbers,mainly involving the regulation of cell fate decisions,embryonic development,and kinds of cancers,etc.However,the mechanism of tumorigenesis influenced by m~6A modification dysregulation in BCa remains elusive.In this study,we explored the biological role of m~6A modification in BCa,and principally focused on the regulatory mechanism of m~6A axis mediated by METTL3 and YTHDF2.The main investigations and results are as follows:1.METTL3/YTHDF2 m~6A is up-regulated in BC cells.And the expression of METTL3 is correlated with YTHDF2 in TCGA database.2.To evaluate the tumor-promoting effects of METTL3 on cell proliferation,BC cell lines T24 and UM-UC-3 were transfected with the homolog-specific si RNA pool and negative control.Then found that knockdown of METTL3 inhibits the proliferation of BC cells by triggering G1-phase arrest.EMT progression was obviously inhibited by depleted METTL3 in BC cells.3.The depletion of YTHDF2 led to remarkable inhibition in BC cells migration displayed by wound healing assay and trans-well assay.EMT progression was obviously inhibited by depleted YTHDF2 in BC cells3.The RNA sequencing of METTL3-depleted T24 cell and online bioinformatic databases were utilized to predict the potential target of METTL3/YTHDF2 m~6A axis.SETD7 was of particular interest and chosen as the candidate target.4.Our study indicated that METTL3/YTHDF2 directly degraded SETD7 m RNA in m~6A dependent manner by Me RIP and RIP assay.5.SETD7 act as distinct tumor suppressor in BCa.We demonstrated that m6A/SETD7/KLF4 axis was involved in the progression of BCa.Consequently,we hope this study will gain an insight to the underlying molecular mechanism of tumorigenesis and provide the potential therapeutic targets for BCa. |
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