Cigarette smoking combined with genetic variation regulates the m6A methylation of CRNKL1 and is associated with bladder cancer risk.

Cigarette smoking was known to accelerate the occurrence and development of bladder cancer by regulating RNA modification. However, the association between the combination of cigarette smoking and RNA modification-related single nucleotide polymorphisms (RNAm-SNPs) and bladder cancer risk remains unclear. In this study, 1681 participants, including 580 cases and 1101 controls, were recruited for genetic association analysis. In total, 1 287 990 RNAm-SNPs involving nine RNA modifications (m6A, m1A, m6Am, 2'-O-Me, m5C, m7G, A-to-I, m5U, and pseudouridine modification) were obtained from the RMVar database. The interactive effect of cigarette smoking and RNAm-SNPs on bladder cancer risk was assessed through joint analysis. The susceptibility analysis revealed that 89 RNAm-SNPs involving m6A, m1A, and A-to-I modifications were associated with bladder cancer risk. Among them, m6A-related rs2273058 in CRNKL1 was associated with bladder cancer risk (odds ratios (OR) = 1.35, padj = 1.78 × 10-4), and CRNKL1 expression was increased in bladder cancer patients (p = 0.035). Cigarette smoking combined with the A allele of rs2273058 increased bladder cancer risk compared with nonsmokers with the G allele of rs2273058 (OR = 2.40, padj = 3.11 × 10-9). Mechanistically, the A allele of rs2273058 endowed CRNKL1 with an additional m6A motif, facilitating recognition by m6A reader IGF2BP1, thereby promoting CRNKL1 expression under cigarette smoking (r = 0.142, p = 0.017). Moreover, elevated CRNKL1 expression may accelerate cell cycle and proliferation, thereby increasing bladder cancer risk. In summary, our study demonstrated that cigarette smoking combined with RNAm-SNPs contributes to bladder cancer risk, which provides a potential target for bladder cancer prevention.