Observation and analysis of KRAS, BRAF gene mutation in tumor tissues of colorectal cancer

SUN Yi; AINIWAER· Aimudula; GULIBIYE· Shabier; XIAO Lei; YANG Ying; BAO Yong-xing

doi:10.3969/j.issn.1002-266X.2014.43.003

Abstract：Objective To observe KRAS , BRAF gene mutational status in tumor tissues of colorectal cancer patients and to analyze the correlation between mutation and clinicopathological feature .Methods Collected surgical removed tumor tissue samples from 100 cases of colorectal cancer patients , which were diagnosed by histological examination .Codons 12, 13 on exons 2 of KRAS genes and exons 15 of BRAF genes were detected by PCR-direct sequencing , to certificate the association between gene mutation and clinicopathological feature of patients .Results KRAS and BRAF mutations were present in 28%(28/100) and 5%(5/100) of patients, respectively.5.6%(4/72) samples were observed in mutation in wild-type BRAF patients.There were 8 types of mutation on KRAS genes , which were most common as G12D, G12V and G13D.Whereas, the BRAF gene mutation had 3 types and V600E was considered as the most prominent one .Mutation rate of KRAS genes was certificated higher in group of olds aged over 60 years than the rest(P<0.05).In addition, a significant increase mutation rate occurred in patients with primary tumors in high differentiation and extrahepatic invasion or metastasis ( P<0.05) .How-ever, BRAF genes mutation rate obviously increased in patients with bigger diameter of liver metastatic lesions (P<0.05). KRAS and BRAF gene mutations were in association with primary tumor sites (all P<0.05).Conclusion There is a higher mutation rate on KRAS genes in tumor tissues of colorectal cancer patients , which is considered as in relation to factors of age, histological grade of primary tumor , extrahepatic invasion or metastasis and primary site .Mutation of BRAF genes is as-sociated with the maximum diameter of liver metastasis and primary tumor sites .