Mechanistic Studies Of Colorectal Cancer Development Mediated By SNPs In Pre-microRNA Terminal-loop

Part I, The association of SNPs in pre-micro RNA terminal-loop with the susceptibility of coloretal cancerObject: To investigate the correlation of the single nucleotide polymorphisms(SNPs) in pre-micro RNA terminal-loop with the susceptibility and clinical features of colorectal cancer.Methods: Firstly, we screened SNPs in pre-micro RNA terminal-loop whose MAF ≥0.1 from the published databases of mi RNASNP 2.0. Secondly, we collected peripheral blood of 1026 colorectal cancer patients and 1026 healthy volunteers and extracted DNA from them. Thirdly, we determined the genotype of the SNPs by using a Mass ARRAY SNP Genotyping platform. Finally, we analyzed the correlation of SNPs with the susceptibility and clinical features of colorectal cancer statistically.Results:(1) We selected 17 SNPs as candidate mi RSNPs whose MAF ≥0.1 among 121 SNPs in pre-micro RNA terminal-loop from the published databases of mi RNASNP 2.0.(2) Seven candidate mi RSNPs were successfully detected by using a Mass ARRAY SNP Genotyping platform.(3) The statiscal analysis showed that the SNP rs7911488 in the terminal-loop of pre-mi R-1307 was significantly correlated to the occurrence of colorectal cancer, and the C allele of rs7911488 was a risk factor for the occurrence of CRC.(4) We found that rs7911488 was markedly associated with the maximum diameter of tumor.Conclusion: The C allele of rs7911488 within the terminal-loop of pre-mi R-1307 is a risk factor for the occurrence and development of colorectal cancer. Part II, The effect of SNP rs7911488 on the regulatory role of micro RNAs and the effect of mi R-1307 on the regulatory role of target geneObjective: To explore the effect of SNP rs7911488 on the regulatory role of micro RNAs and the effect of mi R-1307 on the regulatory role of target gene.Methods: Firstly, we detected the expression of mi R-1307-3p in 20 pairs of CRC tissues and para-cancer tissues. Secondly, we used online software RDPDP to predict the potential binding protein on pre-mi R-1307. Thirdly, we knock-downed or overexpressed the related gene and analyzed the expression of mi R-1307-3p in the CRC cells transfected with rs7911488 T-allelic or C-allelic pre-mi R-1307 expression plasmids. Finally, we predicted and evaluated the potential targets of mi R-1307.Results: The expression of mi R-1307 was apparently low in CRC tissues as compared to the para-cancer tissues. Both MBNL1 and DICER1 participate in processing of T-allelic pre-mi R-1307, while MBNL1 but not DICER1 participates in maturation of mi R-1307 from C-allelic pre-mi R-1307. Mi R-1307 can inhibit the expression of Bcl2 by binding with the 3’-UTR of Bcl2 gene.Conclusion: MBNL1 binds with C-allelic pre-mi R-1307 leading to low expression of mi R-1307-3p, which results in up-regulation of Bcl2 protein in cancer cells.