β -Catenin Mutations in Cell Lines Established from Human Colorectal Cancers

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 94; no. 19; pp. 10330 - 10334
• Main Authors: Ilyas, M., Tomlinson, I. P. M., Rowan, A., Pignatelli, M., Bodmer, W. F.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 16-09-1997; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences of the USA
• Subjects: Amino Acid Sequence; beta Catenin; Biological Sciences; Blotting, Western; Caco 2 cells; Cadherins; Cell lines; Cells; Codon; Codons; Colon cancer; Cytoskeletal Proteins - genetics; DNA, Complementary; Exons; Genetic mutation; Hematocrit; Humans; Medical research; Messenger RNA; Molecular Sequence Data; Mutation; Phosphorylation; Polymorphism, Single-Stranded Conformational; Precipitin Tests; Proteins; RNA, Messenger - genetics; Trans-Activators; Tumor cell line; Tumor Cells, Cultured
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.19.10330

β -catenin has functions as both an adhesion and a signaling molecule. Disruption of these functions through mutations of the β -catenin gene (CTNNB1) may be important in the development of colorectal tumors. We examined the entire coding sequence of β -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 β -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 β -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 β -catenin with α -catenin and APC were detectable. In SW48 and HCA 46, however, we did not detect complexes of β -catenin protein with α -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 β -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.