ABSTRACT
Increasing evidence has indicated that perturbation of cyclins is one of the major factors leading to cancer. The aim of this study was not only to investigate various cell cycle-related kinase activities in hepatocellular carcinoma (HCC), but also to analyze the difference of cell cycle-related kinase activity levels between hepatitis C virus (HCV)-induced HCC and HCV-induced cirrhosis. The protein levels of cyclins D1, E, A, and H, and of cyclin dependent kinase 1 (Cdk1), Cdk2, Cdk4, Cdk6, and Cdk7 in HCC and in surrounding nontumorous cirrhosis were determined by Western blot. The enzymatic activities of cyclins D1, E, A, Cdk1, Cdk4, Cdk6, Cdk7, and Wee1 were measured using in vitro kinase assays. Protein levels and kinase activities of cyclin D1, Cdk4, cyclin E, cyclin A, and Wee1 were significantly elevated in HCC compared with surrounding cirrhotic tissues. The enhanced cyclin D1-related kinase activity in HCC was accompanied by the up-regulation of Cdk4 activity, but not Cdk6 activity. The kinase activities of Cdk6, Cdk7, and Cdk1 did not differ between HCC and surrounding cirrhotic tissues. In addition, the protein levels and kinase activities of cyclin D1, Cdk4, and cyclin E were higher in poorly differentiated HCC and advanced HCC. In conclusion, the increases of cyclin D1, Cdk4, cyclin E, cyclin A, and Wee1 play an important role in the development of HCC from cirrhosis. Cyclin D1, Cdk4, and cyclin E activation may be closely related to the histopathologic grade and progression of HCC.
Subject(s)
CDC2-CDC28 Kinases , Carcinoma, Hepatocellular/metabolism , Cell Cycle Proteins , Cyclin-Dependent Kinases/analysis , Cyclins/analysis , Liver Cirrhosis/metabolism , Liver Neoplasms/metabolism , Nuclear Proteins , Proto-Oncogene Proteins , Aged , Blotting, Western , CDC2 Protein Kinase/analysis , CDC2 Protein Kinase/metabolism , Carcinoma, Hepatocellular/etiology , Carcinoma, Hepatocellular/pathology , Cyclin A/analysis , Cyclin A/metabolism , Cyclin D1/analysis , Cyclin D1/metabolism , Cyclin E/analysis , Cyclin E/metabolism , Cyclin H , Cyclin-Dependent Kinase 2 , Cyclin-Dependent Kinase 4 , Cyclin-Dependent Kinase 6 , Cyclin-Dependent Kinases/metabolism , Cyclins/metabolism , Female , Humans , Liver Cirrhosis/complications , Liver Cirrhosis/pathology , Liver Neoplasms/etiology , Liver Neoplasms/pathology , Male , Middle Aged , Phosphorylation , Protein Serine-Threonine Kinases/analysis , Protein Serine-Threonine Kinases/metabolism , Protein-Tyrosine Kinases/metabolism , Retinoblastoma Protein/metabolism , Cyclin-Dependent Kinase-Activating KinaseABSTRACT
We investigated the frequency and mechanism of beta-catenin/T cell factor (Tcf) signaling activation in a panel of 36 human gastrointestinal and liver cancer cell lines. Reporter assay and electrophoretic mobility shift assay revealed that the beta-catenin/Tcf signaling was upregulated in 12 of 12 (100%) colorectal, 5 of 8 (68%) gastric, 2 of 7 (29%) hepatic, and none of 9 pancreatic cancer cell lines. The activation of the pathway was mainly due to the mutation of adenomatous polyposis coli (APC) or beta-catenin, and Tcf-4 was highly expressed in these cell lines with upregulated signaling. Nuclear beta-catenin was observed not only in the signaling-activated cell lines, but also in 14 of 25 (56%) primary gastric cancers, 15 of 20 (75%) colon cancers, 5 of 19 (26%) hepatocellular carcinomas, and none of 13 pancreatic cancers. The presence of signaling-upregulated gastric cancer cell lines with intact APC and beta-catenin suggests the involvement of other mechanisms than mutations of APC or beta-catenin.
