A modified mutagenic PCR-RFLP method for K-ras codon 12 and 13 mutations detection in NSCLC patients

Evidence from many investigators has shown that mutations in the first exon of K- ras gene occur at elevated frequencies in lung, pancreatic and colon carcinoma and seem to be of prognostic importance. The aim of this study was to develop an effective method for the detection of K- ras mutations in codons 12 and 13 in non-small-cell lung cancer (NSCLC) patients in order to investigate correlation with clinical outcome. DNA was extracted from tumour and neighbouring non-neoplastic lung tissues from 70 patients and screened for codon 12 and 13 mutations. We applied a mutagenic PCR-restriction fragment length polymorphism for both codon 12 and 13 mutation detection. Codon 12 mutation was identified in 20% of NSCLC patients, whereas no codon 13 mutation was detected. As expected, the respective non-neoplastic tissues exhibited no mutations. We observed an increased codon 12 mutation prevalence in adenocarcinoma comparing to other types of carcinomas. Follow-up for 29 patients with a mean time of 12 months indicates an increased relapse rate in NSCLC patients with the K- ras codon 12 mutation. Furthermore, a trend towards increased percentage of mutant samples was observed in the advanced stage group of patients. We provide evidence that our approach is a fast and reliable method for screening K- ras exon 1 mutations in tumour samples from NSCLC patients.