RRC ID 42255
Author Maniratanachote R, Minami K, Katoh M, Nakajima M, Yokoi T.
Title Chaperone proteins involved in troglitazone-induced toxicity in human hepatoma cell lines.
Journal Toxicol Sci
Abstract Troglitazone (TRO), an effective thiazolidinedione antidiabetic agent, was reported to produce idiosyncratic hepatotoxic effects in some individuals. In contrast, rosiglitazone (RSG), in the same group of agents, has no significant toxic effects and now is widely used. In this study, human hepatoma (HepG2) cell lines were exposed to various doses of TRO as well as RSG (0, 25, 50, and 75 microM) for 48 h. Cell lysates were separated by two-dimensional electrophoresis, and the gels were stained with coomassie brilliant blue to compare the spot profiles. The greatest protein expression at a MW of 75 kDa and isoelectric point of 5 was specifically increased with TRO treatments of 50 and 75 microM. The spot was identified as a mixture of immunoglobulin heavy chain binding protein (BiP) and, to a lesser extent, protein disulfide isomerase-related protein (PDIrp). Immunoblot analyses showed that the BiP protein was dose-dependently increased by TRO treatment and, to a lower degree, by RSG. These effects were also correlated with the high induction of BiP mRNA by TRO (50 and 75 microM) and the lower induction by RSG. However, both treatments showed no significant effects on PDIrp expression. The toxic effects of TRO in relation to the overexpression of BiP were also demonstrated in HLE cells, another human hepatoma cell line. In HLE cells, the inhibition of BiP expression by small interference RNA rendered cells more susceptible to the toxic effects of TRO. These results suggest that the overexpression of BiP is a defense mechanism of the endoplasmic reticulum in response to TRO-induced toxicity.
Volume 83(2)
Pages 293-302
Published 2005-2-1
DOI 10.1093/toxsci/kfi022
PII kfi022
PMID 15525695
MeSH Amino Acid Sequence Carcinoma, Hepatocellular / drug therapy Carcinoma, Hepatocellular / metabolism* Carcinoma, Hepatocellular / pathology Cell Line, Tumor / drug effects Cell Survival / drug effects Chromans / toxicity* Dose-Response Relationship, Drug Endoplasmic Reticulum Chaperone BiP Gene Expression Regulation / drug effects Heat-Shock Proteins / antagonists & inhibitors Heat-Shock Proteins / genetics Heat-Shock Proteins / metabolism* Humans Hypoglycemic Agents / toxicity* Liver Neoplasms / drug therapy Liver Neoplasms / metabolism* Liver Neoplasms / pathology Molecular Chaperones / antagonists & inhibitors Molecular Chaperones / genetics Molecular Chaperones / metabolism* Molecular Sequence Data Protein Disulfide-Isomerases Proteins / genetics Proteins / metabolism* RNA Interference RNA, Messenger / metabolism RNA, Small Interfering / biosynthesis RNA, Small Interfering / genetics RNA, Small Interfering / pharmacology Reverse Transcriptase Polymerase Chain Reaction Rosiglitazone Thiazolidinediones / toxicity* Transfection Troglitazone
IF 3.703
Times Cited 23
Human and Animal Cells Hep G2