["Field cancerization"--an additional phenomenon in development of colon tumors? K-ras codon 12 mutations in normal colonic mucosa of patients with colorectal neoplasms].
BACKGROUND
The c-K-ras2-gene (K-ras) encodes the p21ras protein, which participates in the transduction of mitogenic signals from the cell surface to the nucleus. About 40-50% of colorectal cancers bear a point mutation of the K-ras codon 12 within exon I, leading to activation of the K-ras oncogene.


METHODS
Using a polymerase chain reaction (PCR)-based two-step restriction fragment length polymorphism (2sRFLP)-technique, we assessed the frequency of point mutations in the first or second base of K-ras codon 12 in patients suffering from colorectal carcinoma, adenoma, and their normal colon mucosa, respectively.


RESULTS
Similar to other investigators, we found mutations in 7 out of 17 (41%) colorectal carcinomas and 1 out of 4 (25%) adenomas. Using this very sensitive 2sRFLP technique (detection level = 0.2% of mutated cells), we were able to find K-ras codon 12 mutations in normal mucosa in 4 out of 18 (22.2%) patients with colorectal neoplasia.


CONCLUSIONS
This result can be explained by the phenomenon of "field cancerization" or by a local micrometastasis of K-ras-positive tumor cells.
Aivado
M
M
Klinik für Allgemein- und Unfallchirurgie, Heinrich Heine-Universität Düsseldorf. alvesai@uni-duesseldorf.de
Gynes
M
M
Gorelov
V
V
Schmidt
W U
WU
Röher
H D
HD
Goretzki
P E
PE
D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology; D000236:Adenoma / Q000235:genetics* / Q000473:pathology; D000328:Adult; D000368:Aged; D001706:Biopsy; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology; D003062:Codon; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D005091:Exons; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000473:pathology; D008297:Male; D008875:Middle Aged; D017354:Point Mutation / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics*
D003062:Codon; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)