Detection of MSH2 polymorphisms in colorectal cancer samples using high resolution melting analysis

Colorectal Cancer (CRC) as a hetrogenetic disease is the second most common cancer in developed countries. More than 10% of CRC is hereditary, including the syndromes HNPCC and FAP. MSH2 gene is located on chromosome 2 (p21) and involves 16 Exons. MSH2 is a protein with a part in the remedial process of MMR following DNA assimilation. MSH2 is linked to MSH6 or MSH3 and constitutes the complexes MutSα and MutSβ, which oddly identifies small and big insertion/deletion pairs. The present study employs HRMA techniques to trace deletion (mutation) of GTG in the exon12 MSH2 gene. This study mainly aims at both examining applicability and potency of HRMA in detecting GTG deletions and determining the frequencies of such deletions in homozygous and heterozygous modes in large intestinal cancer cases with respect to the control group. To this end, 50 cases of colorectal cancer and 50 normal intestines were examined. First, genomic DNA was extracted from cancerous paraffin-embedded tissues and then it was examined using HRM techniques and determining direct sequence and frequency of GTG deletion. The controls employed included 96 GTG sequence in wild-type mode and 93 GTG in mutant mode, the equal ratio thereof was used for heterozygous mode of this position. The results showed that HRMA technique has a potential to differentiate deletion and insertion of pairs in homozygous and heterozygous modes regarding their melting point differences. Furthermore, GTG deletion frequency of cancerous cases was found to be significantly more than that of healthy people