Lack of association between let-7 binding site polymorphism rs712 and risk of nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is characterized by its highly invasive and metastatic features. Therefore, screening genetic biomarkers of NPC to achieve early diagnose would be of great value for NPC therapy. Single nucleotide polymorphisms in let-7 miRNA binding site in 3' untranslated region of KRAS mRNA have been found to be associated with various cancer risks. In this study, we genotyped the frequency of KRAS rs712 to test its effect on NPC risk in a hospital-based case-control study in a Chinese population, with 188 histologically confirmed NPC patients and 356 cancer-free controls, using polymerase chain reaction-restriction fragment length polymorphism assay. There was no significant difference in the genotype and allele frequencies of the rs712 polymorphism between the NPC patients and the control group (GT vs. GG, OR 0.83, 95% CI 0.57-1.21; TT vs. GG, OR 1.27, 95% CI 0.58-2.75). Our data suggest that the KRAS rs712 polymorphism in let-7 miRNA binding site has no association with NPC risk. Further experiments with larger sample size or other polymorphism sites are needed to verify the result, especially in different ethnic groups.