open access

Vol 49, No 4 (2011)
CASE REPORT
Published online: 2012-01-16
Submitted: 2012-01-16
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Concurrent mutation in exons 1 and 2 of the K-ras oncogene in colorectal cancer

Raffaele Palmirotta, Annalisa Savonarola, Giorgia Ludovici, Maria Laura De Marchis, Renato Covello, Giuseppe Maria Ettorre, Cristiano Ialongo, Fiorella Guadagni
DOI: 10.5603/FHC.2011.0097
·
Folia Histochem Cytobiol 2011;49(4):729-733.

open access

Vol 49, No 4 (2011)
CASE REPORT
Published online: 2012-01-16
Submitted: 2012-01-16

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)

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)
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Keywords

colorectal cancer; K-ras; double mutation

About this article
Title

Concurrent mutation in exons 1 and 2 of the K-ras oncogene in colorectal cancer

Journal

Folia Histochemica et Cytobiologica

Issue

Vol 49, No 4 (2011)

Pages

729-733

Published online

2012-01-16

DOI

10.5603/FHC.2011.0097

Bibliographic record

Folia Histochem Cytobiol 2011;49(4):729-733.

Keywords

colorectal cancer
K-ras
double mutation

Authors

Raffaele Palmirotta
Annalisa Savonarola
Giorgia Ludovici
Maria Laura De Marchis
Renato Covello
Giuseppe Maria Ettorre
Cristiano Ialongo
Fiorella Guadagni

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