title: Greater frequency of K-ras Val-12 mutation in colorectal cancer as detected with sensitive methods.
abstract: Assays for tumor mutations need to be sufficiently sensitive that a mutation can be readily detected in a high background of wild-type sequence. We have evaluated competitive allele-specific oligonucleotide (cASO) hybridization, the amplification refractory mutation system (ARMS), and a combination of cASO with mutant-enriched polymerase chain reaction (ME-PCR) for their respective sensitivities in detecting the K-ras Val-12 mutation. cASO hybridization detected 1 mutant allele in 100 wild-type alleles and identified 6 of 74 (8%) colorectal tumors as having the Val-12 mutation. ARMS detected 1 mutant in 1000 and 12 of 74 (16%) tumor samples, and the ME-PCR with cASO hybridization detected 1 in 5000 and 20 of 74 (27%) tumor samples. The mutation was not detected in normal bowel mucosa from selected Val-12 tumor-positive patients. ME-PCR combined with cASO resulted in a threefold higher detection rate than has previously been reported and suggests that other studies may have underestimated the frequency of K-ras mutations.
authors.affiliation: Department of Clinical Laboratory Sciences, Queen's Medical Centre, Nottingham, UK.
authors.forename: K M
authors.initials: KM
authors.lastname: Carpenter
authors.forename: L G
authors.initials: LG
authors.lastname: Durrant
authors.forename: K
authors.initials: K
authors.lastname: Morgan
authors.forename: D
authors.initials: D
authors.lastname: Bennett
authors.forename: J D
authors.initials: JD
authors.lastname: Hardcastle
authors.forename: N A
authors.initials: NA
authors.lastname: Kalsheker
mesh_terms: D001483:Base Sequence; D015179:Colorectal Neoplasms / Q000235:genetics*; D004252:DNA Mutational Analysis / Q000379:methods*; D011905:Genes, ras; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009693:Nucleic Acid Hybridization; D016133:Polymerase Chain Reaction; D014633:Valine / Q000235:genetics*
chemical_list: D014633:Valine