K-ras oncogene mutations in sporadic colorectal cancer in The Netherlands Cohort Study

K-ras oncogene mutations in sporadic colorectal cancer in The Netherlands Cohort Study

Brink, M.
de Goeij, A.F.P.M.
Weijenberg, M.P.
Roemen, G.M.J.M.
Lentjes, M.H.F.M.
Pachen, M.M.M.
Smits, K.M.
de Bruïne, A.P.
Goldbohm, R.A.
van den Brandt, P.A.

2003

Activation of K-ras oncogene has been implicated in colorectal carcinogenesis, being mutated in 30-60% of the adenocarcinomas. In this study, 737 incident colorectal cancer (CRC) patients, originating from 120 852 men and women (55-69 years at baseline) participating in the Netherlands Cohort Study (NLCS), were studied in order to evaluate subgroups with respect to K-ras mutation status. Mutation analysis of the exon 1 fragment of the K-ras oncogene, spanning codons 8-29, was performed on archival colorectal adenocarcinoma samples of all patients using macrodissection, nested PCR and direct sequencing of purified fragments. The method of mutation detection was validated by the confirmation of reported K-ras status in CRC cell lines, a good correlation between fresh-frozen and routinely fixed, paraffin-embedded tissue, a detection limit of 5% mutated DNA and a good reproducibility. Various types of K-ras mutations were evaluated with respect to tumour sub-localization, Dukes' stage and tumour differentiation. In 37% (271/737) of the patients the exon 1 fragment of K-ras gene was found to be mutated The predominant mutations are G>A transitions and G>T transversions, and codons 12 and 13 are the most frequently affected codons. Patients with a rectal tumour were found to have the highest frequency of G>T transversions as compared with patients with a colon or rectosigmoid tumour. This difference appeared to be confined to women with a rectal tumour harbouring G>T transversions. No significant differences were observed for Dukes' stage with respect to types of K-ras mutation, which does not support direct involvement of the K-ras oncogene in adenocarcinoma progression. The equal distribution of K-ras mutations among cases with or without a family history of colorectal cancer argues against an important role for this mutation in familial colorectal cancer, and could imply that K-ras mutations are more probably involved in environmental mechanisms of colorectal carcinogenesis.

Health Biology
Food and Chemical Risk Analysis
adenine
DNA fragment
guanine
thymine
adult
aged
cancer cell culture
cancer growth
cancer localization
cancer risk
cancer staging
cancer tissue
codon
cohort analysis
colon carcinogenesis
colorectal cancer
controlled study
correlation analysis
DNA purification
environmental factor
exon
familial cancer
family history
female
gene mutation
gene sequence
histopathology
human
human cell
human tissue
incidence
major clinical study
male
mutational analysis
Netherlands
nucleic acid base substitution
oncogene K ras
polymerase chain reaction
priority journal
reproducibility
review
tumor biopsy
tumor differentiation
validation process
Base Sequence
Cohort Studies
Colorectal Neoplasms
DNA Primers
Genes, ras
Humans
Mutation
Netherlands

http://resolver.tudelft.nl/uuid:da383245-9e69-4d2e-87e4-6d8a3cb48d58

https://doi.org/10.1093/carcin/bgg009

237017

0143-3334

Carcinogenesis, 24 (4), 703-710

article