The Association Of MiR-SNP With The Susceptibility Of Colorectal Cancer And Response To Chemotherapy

Part I, The association of miR-SNP with the susceptibility of colorectalcancer and response to chemotherapyObjective: To investigate the correlation of the single nucleotidepolymorphisms(SNPs) in the miRNA with the susceptibility, clinical features andresponse to chemotherapy of colorectal cancer.Methods: Firstly, we screened SNPs in the miRNA by using informatics softwares.Secondly, we collected peripheral blood of300healthy volunteers and175colorectalcancer patients and extracted DNA from them. Then, by allele-specific amplificationmethod, we determined the genotype of the SNPs. Finally, we analyzed the correlationof SNPs with the susceptibility, clinical features and response to chemotherapy ofcolorectal cancer statistically.Results:(1) We analyzed6SNPs in the miRNA and found that the frequencies ofalleles and genotypes (rs2910164, rs895819, rs7911488and rs2292832) weresignificantly different between healthy controls and colorectal cancer patients (P<0.05).Among them, rs7911488and rs2292832were the most important risk factors fordeveloping colorectal cancer. Compared with the rs7911488AA genotype, theindividuals with AG genotype (OR=0.406,95%CI=0.257-0.642) and G allele carriers(OR=0.469,95%CI=0.300-0.732) had a lower risk of suffering from colorectal cancersignificantly. Compared with the rs2292832TT genotype, the individuals with CTgenotype (OR=8.786,95%CI=5.237-14.740) and C allele carriers (OR=4.452,95%CI=2.769-7.159) had a higher risk of suffering from colorectal cancer significantly.There were no significant differences of allelic and genotypic frequency distribution ofrs3746444and rs28599926(P>0.05).(2) The statistical analysis showed that thefrequency of rs3746444TT genotype and rs7911488AA genotype were lower than that of the CT genotype (7.14%vs38.46%) and AG genotype (2.12%vs18.05%) in thepatients at poorer differentiation grades significantly.(3) Our findings also found thatthe rs7911488were significantly correlated with response to chemotherapy of colorectalcancer(P=0.041). Compared with the AA genotype, the individuals with AGgenotype(OR=0.194,95%CI=0.045-0.842) and G allele carriers(OR=0.222,95%CI=0.053-0.940) had a lower effect of chemotherapy. The rs895819genotypes werenearly related to the occurrence of adverse reactions of5FU chemotherapy (P=0.084),Compared with the TT genotype, the CC genotype(OR=3.469,95%CI=0.860-13.989)had a higher adverse reactions.Conclusion: The SNP rs7911488and rs2292832were associated with theoccurrence of colorectal cancer significantly, the rs7911488G allele and rs2292832Tallele may play a protective role in the occurrence of colorectal cancer.Part II, The effect of SNP rs7911488on the regulatory role of microRNAs andthe effect of miR-1307on the regulatory role of target geneObjective: To explore the effect of SNP rs7911488on the regulatory role ofmicroRNAs and the effect of miR-1307on the regulatory role of target gene.Methods: Firstly, we constructed the miR-1307expression vectors of twogenotypes(CC and TT), transfected HEK293t cells, and then determined the miR-1307expression by real-time fluorescent quantitative PCR method. Secondly, we constructedrecombinant luciferase expression vectors of target genes, which include the targetsequences for miR-1307. Thirdly, we co-transfected CHO cells with miRNA and therecombinant vectors. then, by using Dual luciferase reporter system we measured theactivity of luciferase. Finally, we analyzed the effect of SNP rs7911488on theregulation role of miRNAs.Results:(1) Compared with the rs7911488TT genotype, the cells with CCgenotype had a significantly higher of miR-1307(0.032vs0.006).(2) We predicted thetarget genes were RHOA, WNT4and TYMS genes. For TYMS gene, the miR-1307cansignificantly decrease the luciferase activity of the sepcific recombinant constructs(P<0.05). While there were no significant differences in RHOA and WNT4genes(P>0.05). Conclusion: SNP rs7911488CC genotype can promote the expression of miR-1307.Which indicated that the TYMS gene was inhibited by miR-1307significantly. SummaryIn this study, we discovered that SNP rs7911488was associated with thesusceptibility of colorectal cancer, and the G allele carriers had a lower risk ofcolorectal cancer. We also found that SNP rs7911488disrupted the regulatory role ofmiR-1307, resulting in dysregulation of TYMS, and thus participated in the drugresistance of colorectal cancer. These findings provide a new perspective to study thegenetic etiology of colorectal cancer and illustrate the mechanism of the drug resistanceof cancer mediated by miR-SNP.