Vol 49, No 4 (2011)
Case report
Published online: 2012-01-16
Concurrent mutation in exons 1 and 2 of the K-ras oncogene in colorectal cancer
DOI: 10.5603/FHC.2011.0097
Folia Histochem Cytobiol 2011;49(4):729-733.
Abstract
The K-ras gene is frequently mutated in colorectal cancer and has been associated with tumor initiation
and progression; approximately 90% of the activating mutations are found in codons 12 and 13 of exon 1
and just under 5% in codon 61 located in exon 2. These mutations determine single aminoacidic substitutions in
the GTPase pocket leading to a block of the GTP hydrolytic activity of the K-ras p21 protein, and therefore to its
constitutive activation. Point mutations in sites of the K-ras gene, other than codons 12, 13 and 61, and other
types of genetic alterations, may occur in a minority of cases, such as in the less frequent cases of double mutations
in the K-ras gene. However, all mutations in this gene, even those which occur in non-canonical sites or
double mutations, are relevant oncogenic alterations in colorectal cancer and may underlie K-ras pathway hyperactivation.
In the present study, we report the case of a patient with colorectal cancer presenting a concurrent
point mutation in exons 1 and 2 of the K-ras gene, a GGT to TGT substitution (Glycine to Cysteine) at
codon 12, and a GAC to AAC substitution (Aspartic Acid to Asparagine) at codon 57. In addition, we found in
the same patient’s sample a silent polymorphism at codon 11 (Ala11Ala) of exon 1. (Folia Histochemica et
Cytobiologica 2011; Vol. 49, No. 4, pp. 729–733)
Keywords: colorectal cancerK-rasdouble mutation
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