Comparative study of mutations in SNP loci of K-RAS, hMLH1 and h MSH2 genes in neoplastic intestinal polyps and colorectal cancer

AIM:To clarify the molecular mechanism involved in pathogenesis of colorectal cancer as well as clinical significance of genetic analysis of histological samples.METHODS:A total of 480 blood and tissue specimens were collected in our hospital from January 2011 to October 2012.In the observation group,there were120 blood specimens and 120 intestinal tract tissue specimens collected from patients with neoplastic intestinal polyps.In the control groupⅠthere were80 blood specimens and 80 intestinal tract tissue specimens collected from patients with colorectal cancer.In the control groupⅡthere were 40 blood specimens and 40 intestinal tract tissue specimens collected from healthy individuals.The gene segments were amplified using PCR and DNA gel electrophoresis along with DNA sequence analysis were employed for the detection of the following single nucleotide polymorphisms(SNPs):K-RAS codons 12 and 13;h MLH1(human mut S homolog 1)gene missense mutation at Va1384Asp;h MSH2(human mut S homolog2)gene missense mutation at 2783C/A.RESULTS:The mutation rate of the SNP at Va1384Asp locus of the h MLH1 gene from blood and tissue specimens in the observation group showed no statistical difference from those in the control groupⅠ.The mutation rates of SNPs in codons 12 and 13 of K-RAS and at 2783C/A locus of the h MSH2 gene were significantly lower in the observation group than in the control groupⅠ(χ2=15.476,29.670,10.811,16.618,33.538,7.898,P<0.05).The mutation rate of SNP at Va1384Asp locus of the h MLH1 gene was significantly higher in the observation group when compared to the control groupⅡ(χ2=10.486,4.876,P<0.05).The mutation rates of SNPs in codons 12 and 13 of K-RAS and at 2783C/A locus of the h MSH2 gene did not show any statistical difference from those in the control groupⅡ.CONCLUSION:There may be important clinical significance and relevance between neoplastic intestinal polyps and colorectal cancer in terms of the mechanisms involved in the pathogenesis