MiR-196a binding-site SNP regulates RAP1A expression contributing to esophageal squamous cell carcinoma risk and metastasis.

Polymorphisms in 3' untranslated region (UTR) of cancer-related genes might affect regulation by microRNA (miRNA) and contribute to carcinogenesis. In this study, we screened several single nucleotide polymorphisms (SNPs) in 3'UTR of cancer-related genes and investigated their effects on the risk of esophageal squamous cell carcinoma (ESCC). First, we used SNaPshot assay to genotype seven 3'UTR SNPs in 537 ESCC cases and 608 normal controls in a Chinese Han population and found that SNP rs6573 in 3'UTR of RAS-related proteins (RAP1A) was significantly associated with ESCC risk [P = 0.02, odds ratio (OR) = 0.43; 95% confidence interval (CI): 0.21-0.91] and pathologic stage (P = 0.03, OR = 1.89; 95% CI: 1.06-3.36). A putative binding site for miRNA-196a (miR-196a) exists in the 3'UTR of RAP1A, and the genetic variant, rs6573 A→C, is present in this binding region. We confirmed that miR-196a regulated the expression of RAP1A by luciferase reporter assay and that the regulation was affected by the RAP1A genotype. SNP rs6573 A to C change interfere in the interaction of miR-196a binding to RAP1A 3'UTR, resulting in higher constitutive expression of RAP1A. Moreover, we observed that RAP1A was overexpressed in the majority of ESCC tissues and correlated with RAP1A genotype and lymph node metastasis. In vitro study indicated RAP1A might function as a promoter for esophageal cancer cell migration and invasion through matrix metalloproteinase 2. Our study highlights RAP1A and SNP rs6573 functioning as potential personal diagnostic and prognosis markers for ESCC.