Beta-catenin mutations in cell lines established from human colorectal cancers.
beta-catenin has functions as both an adhesion and a signaling molecule. Disruption of these functions through mutations of the beta-catenin gene (CTNNB1) may be important in the development of colorectal tumors. We examined the entire coding sequence of beta-catenin by reverse transcriptase-PCR (RT-PCR) and direct sequencing of 23 human colorectal cancer cell lines from 21 patients. In two cell lines, there was apparent instability of the beta-catenin mRNA. Five different mutations (26%) were found in the remaining 21cell lines (from 19 patients). A three-base deletion (codon 45) was identified in the cell line HCT 116, whereas cell lines SW 48, HCA 46, CACO 2, and Colo 201 each contained single-base missense mutations (codons 33, 183, 245, and 287, respectively). All 23 cell lines had full-length beta-catenin protein that was detectable by Western blotting and that coprecipitated with E-cadherin. In three of the cell lines with CTNNB1 mutations, complexes of beta-catenin with alpha-catenin and APC were detectable. In SW48 and HCA 46, however, we did not detect complexes of beta-catenin protein with alpha-catenin and APC, respectively. These results show that selection of CTNNB1 mutations occurs in up to 26% of colorectal cancers from which cell lines are derived. In these cases, mutation selection is probably for altered beta-catenin function, which may significantly alter intracellular signaling and intercellular adhesion and may serve as a complement to APC mutations in the early stages of tumorigenesis.
Ilyas
M
M
Cancer Genetics and Immunology Laboratory, Imperial Cancer Research Fund, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom. ilyas@europa.lif.icnet.uk
Tomlinson
I P
IP
Rowan
A
A
Pignatelli
M
M
Bodmer
W F
WF
D000595:Amino Acid Sequence; D015153:Blotting, Western; D003062:Codon; D003598:Cytoskeletal Proteins / Q000235:genetics*; D018076:DNA, Complementary; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D018807:Polymorphism, Single-Stranded Conformational; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000235:genetics; D015534:Trans-Activators; D014407:Tumor Cells, Cultured; D051176:beta Catenin
C495270:CTNNB1 protein, human; D003062:Codon; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; D015534:Trans-Activators; D051176:beta Catenin