title: Mutational spectrum of beta-catenin, AXIN1, and AXIN2 in hepatocellular carcinomas and hepatoblastomas.
abstract: Activation of Wnt signaling through beta-catenin mutations contributes to the development of hepatocellular carcinoma (HCC) and hepatoblastoma (HB). To explore the contribution of additional Wnt pathway molecules to hepatocarcinogenesis, we examined beta-catenin, AXIN1 and AXIN2 mutations in 73 HCCs and 27 HBs. beta-catenin mutations were detected in 19.2% (14 out of 73) HCCs and 70.4% (19 out of 27) HBs. beta-catenin mutations in HCCs were primarily point mutations, whereas more than half of the HBs had deletions. AXIN1 mutations occurred in seven (9.6%) HCCs and two (7.4%) HBs. The AXIN1 mutations included seven missense mutations, a 1 bp deletion, and a 12 bp insertion. The predominance of missense mutations found in the AXIN1 gene is different from the small deletions or nonsense mutations described previously. Loss of heterozygosity at the AXIN1 locus was present in four of five informative HCCs with AXIN1 mutations, suggesting a tumor suppressor function of this gene. AXIN2 mutations were found in two (2.7%) HCCs but not in HBs. Two HCCs had both AXIN1 and beta-catenin mutations, and one HCC had both AXIN2 and beta-catenin mutations. About half the HCCs with AXIN1 or AXIN2 mutations showed beta-catenin accumulation in the nucleus, cytoplasm or membrane. Overall, these data indicate that besides the approximately 20% of HCCs and 80% of HBs with beta-catenin mutations contributing to hepatocarcinogenesis, AXIN1 and AXIN2 mutations appear to be important in an additional 10% of HCCs and HBs.
authors.affiliation: Division of Experimental Pathology, Mayo Clinic, Rochester, Minnesota, MN 55905, USA.
authors.forename: Ken
authors.initials: K
authors.lastname: Taniguchi
authors.forename: Lewis R
authors.initials: LR
authors.lastname: Roberts
authors.forename: Ileana N
authors.initials: IN
authors.lastname: Aderca
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Dong
authors.forename: Chiping
authors.initials: C
authors.lastname: Qian
authors.forename: Linda M
authors.initials: LM
authors.lastname: Murphy
authors.forename: David M
authors.initials: DM
authors.lastname: Nagorney
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Burgart
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Roche
authors.forename: David I
authors.initials: DI
authors.lastname: Smith
authors.forename: Julie A
authors.initials: JA
authors.lastname: Ross
authors.forename: Wanguo
authors.initials: W
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D060466:Axin Protein; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D018197:Hepatoblastoma / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D019656:Loss of Heterozygosity; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D011506:Proteins / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012097:Repressor Proteins; D017384:Sequence Deletion; D015398:Signal Transduction; D015534:Trans-Activators; D014407:Tumor Cells, Cultured; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin
chemical_list: C555451:AXIN1 protein, human; C491761:AXIN2 protein, human; D060466:Axin Protein; C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D004273:DNA, Neoplasm; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin