Analysis of common mutations of KRAS gene in patients suffering from sporadic colorectal cancer in Khuzestan province

Colorectal cancer (CRC) is one of the most common malignancies in the world (rate of death: 33%). v-Ki-ras2 Kirsten rat sarcoma (KRAS) mutations represent an early event in the development and progression of CRC. Codons 12 and 13 of exon 1 are the hot spots for occurrence of mutations in KRAS. This study is attempted to define the occurrence of KRAS mutations at codon 12 and 13 in patients from Khuzestan suffering from sporadic colorectal cancer (SCRC) and compare them with patients from other regions of Iran and other countries. Genomic DNA was first extracted from 45 SCRC specimens. KRAS point mutations were genotyped by PCR-RFLP analysis followed by enrichment PCR. Enrichment PCR is an appropriate method which we use for detecting even lower percentage of heterozygous mutations in one specimen. Finally Sanger sequencing was used to confirm mutations identified. 13.33% of (6 out of 45) tumor samples showed mutations at codon 12 or 13 of the KRAS gene. It’s totally different with the frequency of those from many of other countries (33-53%) and alternative studies in Iran (20.3% and 28%); that could be because of various reasons such as less role of serrated pathway in development of CRC among Khuzestani population, probable microsatellite instability-high status of these tumors, insufficient sensitivity of RFLP method, different genetic and environmental factors like high intake of omega-3 fat in the Khuzestani usual diet. Also, use of enrichment method, doubled the frequency of mutations identified in this cohort.