Polymorphisms Within Micro-RNA Bonding-sites And Risks Of Nasopharygeal Carcinoma

MicroRNAs(miRNAs) are endogenous 22nt small non-coding single stranded RNAs that bind with target mRNAs and function as posttranscriptional regulators of gene expression by either promoting mRNA degradation or translational silencing. The critical region for miRNA binding to mRNA is the 'seed region'(nucleotides 2-7 from the 5'end of the miRNA),which most often binds to a target site in the 3'UTR of the genes by perfect Watson-Crick complementarity.Single nucleotide polymorphisms(SNPs) build the essence of human genetic diversity.Recently,genome-wide analysis(GWA) studies of human SNPs have revealed that nocoding variation in the regulatory sites are more like to be a associated with disease than the coding region variations.Previous studies have described several putative functional SNPs in miRNA target sites.Whether SNPs located at miRNA binding sites can affect the expression of the miRNA target? Several researchers have conducted on these projects since 2007and recent studies have demonstrated that several putative functional SNPs in miRNA target sites may contribute to the susceptibility of humans to common diseases,For example,breast cancer,colorectal cancer,lung cancer and gastrointestinal cancers.However,Little is known about whether variability of miRNA target sites could have impact on the nasopharyngeal carcinoma risk.Thouse,The purpose of this study was to screen SNPs of NPC candidate genes,which might modify miRNA-binding predicted by bioinformatics analysis and to assess the association with NPC.Based on the literatures related to genetic susceptibility of nasopharyngeal carcinoma,by analyzing seven hallmarks,including self-sufficiency in growth signals, evasion of apoptosis,insensitivity to growth inhibitory signals,limitless replicative potential,sustained angiogenesis,tissue invasion and metastasis,and cancer related inflammation that are involved in NPC,We summarized 82 genes were the most characterized and studied in NPC.We downloaded human SNPs in the 3' UTRs of 82 candidate genes from NCBI database and identified putative miRNA-binding sites by specialized algorithms(PicTar,miRanda,TargetScan,and RNAfold webserve).220 SNPs were identified in miRNA-binding sites.Thus,We focused on the 9 genes,including EGFR,COX2,CCNE1,hTERT,MMP2,MMP9,NF-κB VEGF and WNT3 for further investigation due to significant overexpression in NPC.We evaluated the miRNA-binding sites SNPs by assessing the MAF(MAF＞0.05) and free energy.Therefore,a sequence analysis of targeted region was carried out to identify the potential variants of the candidate genes in 3'UTR.SNPS in 3'UTRs were identified by directly sequencing of genomic DNAs derived from 12 randomly selected patients and 12 controls,three SNPs,such as EGFR rs884225,CCNE1 rs3218073 and MMP2 rs7201 were found for next stage work.The study was carried out on a series of167 NPC cases and 171 controls from Guangdong province,a population with the highest worldwide incidence of NPC to research the distribution frequencies of the genotype. Here,we report results from the study.We found statistically significant associations between risk of NPC and variant genotypes of CCNE1 rs3218073,for TC+TT(OR＝1.585;95%CI＝1.023～2.458 P＝0.046),for allele T(OR＝1.464,95%CI＝1.012～2.118;P＝0.042).A significant association between rs3218073 genotype TC(OR＝1.959,P＝0.043),T allele (OR＝2.123,P＝0.006) and later primary tumor(T3-T4) was retrieved.Moreover,the genotype TC(OR＝1.959,P＝0.043),T allele(OR＝2.123,P＝0.006) of rs3218073 also showed an increased risk of higher stage(Ⅲ-Ⅳ).Analysis of the MMP2 rs7201and EGFR rs884225 genotype frequencies were performed in 116 NPC cases vs 143 controls and 167 NPC cases vs 171 controls, respectively.Allele case-control,and genotype case-control test statistics did not identify statistically significant association involving the two polymorphisms in NPC (p＞0.05),according to MMP2 rs7201(the variant heterozygous AC OR＝0.69,95% CI 0.404～1.124;allele C OR＝0.769,95%CI＝0.509～1.161 p＝0.135) and to EGFR rs884225(the variant heterozygous AG OR＝1.375,95%CI＝0.850～2.224,p＝0.194; the homozygotes variant GG OR＝0.844,95%CI＝0.460～1.550 p＝0.584;allele G OR＝0.969,95%CI＝0.714～1.315,p＝0.839).In conclusion,CCNE1 rs3218073 polymorphisms located at miRNA-151 binding sites through bioinformation prediction,T allele was associated with susceptibility to NPC and correlated with staging.Experimental assays will determine the functional effects of miRNA- 151 and rs3218073 polymorphisms.