Modified mismatch polymerase chain reaction-restriction fragment length polymorphism detected mutations in codon 12 and 13 of exon 2 of K-rasgene in colorectal cancer patients and its association with liver metastases: Data from a South Asian country.
OBJECTIVE
Mutations in K-ras codon 12 and 13 of exon 2 are known to affect prognosis and impart resistance to anti-epidermal growth factor monoclonal antibody therapy in colorectal carcinoma (CRC). Our aim was to investigate the utility value of modified mismatch polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay to detect mutation in K-ras codons of CRC patients and to relate the mutational status to liver metastasis.


METHODS
Mismatch PCR-RFLP was developed to detect K-ras mutations in DNA isolated from paraffinized tumor tissue of thirty CRC patients. All patients had 5 year follow-up data to detect liver metastasis. Cross-tabulations were generated between K-ras mutations and the metastatic status. The Chi-square test was used to indicate statistical significance of the association.


RESULTS
Of the 30 CRC patients investigated, K-ras mutations of codons 12 and/or 13 of exon 2 were detected in 14 (46.6%). Meanwhile, 13 patients (43.3%) were observed to have developed liver metastases. There was a significant association between the presence of the K-ras mutation in codon 12 and the occurrence of liver metastasis (χ2 = 4.693, P = 0.030) on the contrary to the mutation in codon 13 to which such occurrence of liver metastases was not seen (χ2 = 1.884, P = 0.169).


CONCLUSIONS
Codon 12 of exon 2 of K--ras gene detected by modified mismatch PCR-RFLP assay is significantly associated with liver metastasis in CRC patients during the first 5 years after surgery. Thus, modified mismatch PCR-RFLP protocol is a suitable method in this setting to detect K-ras gene mutations predicting liver metastasis in CRC patients.
Department of Chemistry, Faculty of Science, University of Colombo, Colombo, Sri Lanka.
Fathima Dhilhani Mohamed
FD
Faleel
Department of Surgery, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka.
M I M De
MI
Zoysa
Department of Pathology, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka.
M D S
MD
Lokuhetti
Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.
Y I N S
YI
Gunawardena
Department of Chemistry, Faculty of Science, University of Colombo, Colombo, Sri Lanka.
Vishvanath Naduviladath
VN
Chandrasekharan
Department of Chemistry, Faculty of Science, University of Colombo, Colombo, Sri Lanka.
Ranil Samantha
RS
Dassanayake
D003062:Codon; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology* / Q000601:surgery; D005091:Exons; D005260:Female; D005500:Follow-Up Studies; D011905:Genes, ras; D020022:Genetic Predisposition to Disease; D006801:Humans; D008113:Liver Neoplasms / Q000556:secondary*; D008297:Male; D009154:Mutation; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length
D003062:Codon