K-ras mutation detection in colorectal cancer using the Pyrosequencing technique.
The identification of gene mutations is a critical goal for the assessment of diagnosis and prognosis in cancer disease, particularly by direct sequencing. Pyrosequencing is a straightforward, non-electrophoretic DNA sequencing method using the luciferase-luciferin light release as a signal for nucleotide incorporation into a PCR template DNA. In this study, we aimed to investigate mutations in the K-ras gene using Pyrosequencing technology, because its reliable chemistry and robust detection mechanism allow for rapid, real-time detection of sequencing events. For the simultaneous detection of the predominant K-ras codons 12 and 13 mutations, we established a sequencing protocol based on the design of a single PCR primer pair and a single sequencing primer. The assay has been validated with DNA from 65 colorectal carcinomas. Furthermore, analysis of the rare K-ras codon 61 mutation was included. In 29% (19/65) of the patients, the K-ras gene was found to be mutated, whereas codons 12 and 13 were most frequently affected (18/65, 27.7%). Mutations with the highest frequency were G-->A transitions (12/19, 63%), followed by G-->T transversions (5/19, 26%). Overall survival was significantly shorter in patients with a tumor containing K-ras codon 12 mutations than in those without K-ras codon 12 mutations (p=0.024). In conclusion, we found Pyrosequencing to be a suitable technology for fast detection of hot-spot mutations in the K-ras oncogene. We demonstrated an important relationship between K-ras codon 12 mutations and overall survival in colorectal cancer patients.
Poehlmann
Angela
A
Department of Pathology, Otto-von-Guericke University, Magdeburg, Germany.
Kuester
Doerthe
D
Meyer
Frank
F
Lippert
Hans
H
Roessner
Albert
A
Schneider-Stock
Regine
R
D000230:Adenocarcinoma / Q000235:genetics* / Q000401:mortality; D001483:Base Sequence; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000401:mortality; D020732:Cytogenetic Analysis / Q000379:methods*; D004252:DNA Mutational Analysis / Q000379:methods; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000235:genetics*; D011905:Genes, ras; D006801:Humans; D053208:Kaplan-Meier Estimate; D008969:Molecular Sequence Data; D009154:Mutation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity
D017931:DNA Primers; D004273:DNA, Neoplasm