title: Troglitazone but not rosiglitazone induces G1 cell cycle arrest and apoptosis in human and rat hepatoma cell lines.
abstract: Rosiglitazone (RSG), an agonist of peroxisome proliferator-activated receptor gamma (PPARgamma), induces minor toxicity in humans relative to another PPARgamma agonist, troglitazone (TRO). In contrast, recent reports suggest that RSG causes growth arrest and apoptosis of normal and cancerous cells. Therefore, in this study, we investigated the relative toxicities of TRO and RSG on three different hepatoma cell lines, and observed that TRO, but not RSG, was cytotoxic. Additionally, we studied the mechanism by which TRO induced damage to HepG2 hepatoma cells. Our results indicated that TRO increased the levels of p53, p27, and p21, while it reduced the levels of cyclin D1 and phospho-Rb in a time-dependent manner. Increased p27 and p21 levels coincided with reduced activities of cell cycle dependent kinases (cdk) such as cdk2- and cyclin A-protein kinases 24 h after TRO treatment. These results demonstrate that TRO, but not RSG, causes G1 arrest of hepatoma cells, most likely through changing the levels of cell cycle regulators. Furthermore, because RSG did not affect the levels of cell cycle regulators, TRO-mediated growth inhibition appears independent of PPARgamma activation.
authors.affiliation: Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, NIH, 12420 Parklawn Drive, Rockville, MD 20852, USA.
authors.forename: Myung-Ae
authors.initials: MA
authors.lastname: Bae
authors.forename: Herman
authors.initials: H
authors.lastname: Rhee
authors.forename: Byoung J
authors.initials: BJ
authors.lastname: Song
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D042846:CDC2-CDC28 Kinases; D002453:Cell Cycle / Q000187:drug effects*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002839:Chromans / Q000494:pharmacology*; D019925:Cyclin A / Q000378:metabolism; D019938:Cyclin D1 / Q000378:metabolism; D019927:Cyclin E / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D016193:G1 Phase / Q000187:drug effects*; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D000077154:Rosiglitazone; D013844:Thiazoles / Q000494:pharmacology*; D045162:Thiazolidinediones; D000077288:Troglitazone; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C493956:CDKN1A protein, human; C493958:Cdkn1a protein, rat; C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D002839:Chromans; D019925:Cyclin A; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D013844:Thiazoles; D045162:Thiazolidinediones; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D000077154:Rosiglitazone; D019938:Cyclin D1; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; C495892:Cdk2 protein, rat; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D000077288:Troglitazone