Genetic Variants in m6A-Switches Among hnRNP C Binding Sites are Associated with Bladder Cancer Risk

Objective: N6-Methyladenosine (m6A), an abundant and prevalent chemical modification on RNA, is involved in multiple biological processes. Recent reports have identified that m6A guides the interaction of RNA-binding proteins such as hnRNP C and their target RNAs, which is termed as m6A-switches. Here we aim to investigate the contribution of genetic variants in m6A-switches to the development of bladder cancer. Methods: A two-stage case-control study was performed to systematically evaluate the association of genetic variants in m6A-switches with bladder cancer risk in 3,997 subjects (discovery stage: 578 cases and 1,006 controls; validation stage: 1,026 cases and 1,387 controls). The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), GTEx Portal and m6AVar were used to conduct bioinformatics analysis. The real-time PCR (RT-PCR) was conducted to detect the relative SOD2 mRNA expression level. Results: We identified that rs5746136 (G>A) in m6A-switches was significantly associated with the reduced risk of bladder cancer (addictive model in discovery stage: adjusted OR = 0.80, 95%CI = 0.69-0.93, P = 3.6—10-3; validation stage: adjusted OR = 0.88, 95%CI= 0.79-0.99, P = 3.0—10-2). In combined analysis, the P value for the association between rs5746136 and bladder cancer reached 4.0—10-4 (adjusted OR = 0.85, 95%CI = 0.78-0.93). Using expression quantitative trait locus (eQTL) analysis and public database, we observed that rs5746136 A allele reduced the expression level of SOD2 in bladder tissues. SOD2 was abnormally expressed in bladder cancer and correlated to m6A modifying enzymes. Conclusion: Our findings uncovered the important role of genetic variants in m6A-switches in bladder cancer susceptibility and indicated that the aberrant expression of SOD2 may be biologically relevant to bladder carcinogenesis. Funding: National Natural Science Foundation of China (81473050), Jiangsu Provincial 333 project, Collaborative Innovation Center for Cancer Personalized Medicine, and the Priority Academic Program Development of Jiangsu Higher Education Institutions (Public Health and Preventive Medicine). Declaration of Interest: The authors declare no competing financial interests. Ethical Approval: This study was approved by the Institutional Review Board of Nanjing Medical University.