P53 mutation as a source of aberrant beta-catenin accumulation in cancer cells.
beta-catenin is involved in both cell-cell interactions and wnt pathway-dependent cell fate determination through its interactions with E-cadherin and TCF/LEF transcription factors, respectively. Cytoplasmic/nuclear levels of beta-catenin are important in regulated transcriptional activation of TCF/LEF target genes. Normally, these levels are kept low by proteosomal degradation of beta-catenin through Axin1- and APC-dependent phosphorylation by CKI and GSK-3beta. Deregulation of beta-catenin degradation results in its aberrant accumulation, often leading to cancer. Accordingly, aberrant accumulation of beta-catenin is observed at high frequency in many cancers. This accumulation correlates with either mutational activation of CTNNB1 (beta-catenin) or mutational inactivation of APC and Axin1 genes in some tumors. However, there are many tumors that display beta-catenin accumulation in the absence of a mutation in these genes. Thus, there must be additional sources for aberrant beta-catenin accumulation in cancer cells. Here, we provide experimental evidence that wild-type beta-catenin accumulates in hepatocellular carcinoma (HCC) cells in association with mutational inactivation of p53 gene. We also show that worldwide p53 and beta-catenin mutation rates are inversely correlated in HCC. These data suggest that inactivation of p53 is an important cause of aberrant accumulation of beta-catenin in cancer cells.
Cagatay
Tolga
T
Department of Molecular Biology and Genetics, Bilkent University, 06533 Ankara, Turkey.
Ozturk
Mehmet
M
D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009154:Mutation; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D051176:beta Catenin
C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D016159:Tumor Suppressor Protein p53; D051176:beta Catenin