Recent evidence indicates that small noncoding RNA molecules known as microRNAs (miRNAs) can function as tumor suppressors and oncogenes. Mutation, misexpression, and altered mature miRNA processing are implicated in carcinogenesis and tumor progression. Because SNPs in pre-miRNAs could alter miRNA processing, expression, and/or binding to target mRNA, we conducted a systematic survey of common premiRNA SNPs and their surrounding regions and evaluated in detail the association of 4 of these SNPs with the survival of individuals with non-small cell lung cancer (NSCLC). When we assumed that disease susceptibility was inherited as a recessive phenotype, we found that the rs11614913 SNP in hsa-mir-196a2 was associated with survival in individuals with NSCLC. Specifically, survival was significantly decreased in individuals who were homozygous CC at SNP rs11614913. In the genotype-phenotype correlation analysis of 23 human lung cancer tissue samples, rs11614913 CC was associated with a statistically significant increase in mature hsa-mir-196a expression but not with changes in levels of the precursor, suggesting enhanced processing of the pre-miRNA to its mature form. Furthermore, binding assays revealed that the rs11614913 SNP can affect binding of mature hsa-mir-196a2-3p to its target mRNA. Therefore, the rs11614913 SNP in hsa-mir-196a2 may be a prognostic biomarker for NSCLC. Further characterization of miRNA SNPs may open new avenues for the study of cancer and therapeutic interventions.

Small, noncoding RNA molecules, called microRNAs (miRNAs), are thought to function as either tumor suppressors or oncogenes. Common single-nucleotide polymorphisms (SNPs) in miRNAs may change their property through altering miRNA expression and/or maturation, and thus they may have an effect on thousands of target mRNAs, resulting in diverse functional consequences. However, it remains largely unknown whether miRNA SNPs may alter cancer susceptibility. We evaluated the associations of selected four SNPs (rs2910164, rs2292832, rs11614913, and rs3746444) in pre-miRNAs (hsa-mir-146a, hsa-mir-149, hsa-mir-196a2, and hsa-mir-499) with breast cancer risk in a case-control study of 1,009 breast cancer cases and 1,093 cancer-free controls in a population of Chinese women and we found that hsa-mir-196a2 rs11614913:T>C and hsa-mir-499 rs3746444:A>G variant genotypes were associated with significantly increased risks of breast cancer (odds ratio [OR], 1.23; 95% confidence interval [CI], 1.02-1.48 for rs11614913:T>C; and OR, 1.25; 95% CI, 1.02-1.51 for rs3746444:A>G in a dominant genetic model) in a dose-effect manner (P for trend was 0.010 and 0.037, respectively). These findings suggest, for the first time, that common SNPs in miRNAs may contribute to breast cancer susceptibility. Further functional characterization of miRNA SNPs and their influences on target mRNAs may provide underlying mechanisms for the observed associations and disease etiology.

microRNAs (miRNA) are a new class of non-proteincoding, small RNAs that function as tumor suppressors or oncogenes. They participate in diverse biological pathways and function as gene regulators. Recently, we conducted a survey of common single nucleotide polymorphisms (SNP) in miRNA sequences and reported that, among four SNPs (rs2910164, rs2292832, rs11614913, and rs3746444) in pre-miRNAs, rs11614913 in miR-196a2 might affect mature miR-196a expression and target mRNA-binding activity and was significantly associated with non-small cell lung cancer survival. However, it remains largely unknown whether miRNA SNPs may alter lung cancer susceptibility. In the current study, we evaluated associations between the above four SNPs in pre-miRNAs and lung cancer susceptibility in a case-control study of 1,058 incident lung cancer patients and 1,035 cancer-free controls in a Chinese population. We found that miR-196a2 rs11614913 variant homozygote CC was associated with f25% significantly increased risk of lung cancer compared with their wild-type homozygote TT and heterozygote TC (odds ratio, 1.25; 95% confidence interval, 1.01-1.54). However, no significant effects were observed on the association between the other three SNPs and lung cancer risk. These findings suggest that functional SNP rs11614913 in miR-196a2 could also contribute to lung cancer susceptibility.

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