OBJECTIVEThe goal of this study is to investigate the inappropriate activation of Wnt pathway in the hepatocarcinogenesis.

METHODSWe analyzed the alterations of three key components of Wnt pathway, beta-catenin, glycogen synthase kinase 3beta (GSK-3beta) and T cell factor 4 (Tcf-4), in 34 samples of hepatocellular carcinoma (HCC) and paracancerous normal liver by immunohistochemistry, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), direct sequencing, semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization.

RESULTSWe found 61.8% (21/34) of all the HCCs examined showed an abnormal beta-catenin protein accumulation in the cytoplasm or nuclei. RT-PCR-SSCP and direct sequencing showed that beta-catenin exon 3 mutations existed in 44.1% (15/34) of the HCCs. No mutations of GSK-3beta or Tcf-4 were detected in HCCs. Moreover, mRNA of beta-catenin and Tcf-4 but not GSK-3beta was found to be over expressed in HCCs. On analyzing the relationship between alterations of beta-catenin or Tcf-4 and C-myc or Cyclin D1 expression, we found that the mutations of beta-catenin as well as over expression of beta-catenin or Tcf-4 gene were independently correlated with C-myc gene over expression in HCCs.

CONCLUSIONSOur present findings strongly suggest mutations of beta-catenin as well as over expression of beta-catenin and Tcf-4 gene activate the Wnt pathway in HCC independently with the target gene most likely to be C-myc.

Carcinoma, Hepatocellular ; metabolism ; Cytoskeletal Proteins ; genetics ; physiology ; Glycogen Synthase Kinase 3 ; genetics ; physiology ; Glycogen Synthase Kinase 3 beta ; Humans ; Immunohistochemistry ; Liver Neoplasms ; metabolism ; Polymerase Chain Reaction ; Polymorphism, Single-Stranded Conformational ; Proto-Oncogene Proteins ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; TCF Transcription Factors ; Trans-Activators ; genetics ; physiology ; Transcription Factor 7-Like 2 Protein ; Transcription Factors ; genetics ; physiology ; Wnt Proteins ; Zebrafish Proteins ; beta Catenin