Gene expression analysis of troglitazone reveals its impact on multiple pathways in cell culture: a case for in vitro platforms combined with gene expression analysis for early (idiosyncratic) toxicity screening.
Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists of the thiazolidinedione family are used for the treatment of type 2 diabetes mellitus due to their ability to reduce glucose and lipid levels in patients with this disease. Three thiazolidinediones that were approved for treatment are Rezulin (troglitazone), Avandia (rosiglitazone), and Actos (pioglitazone). Troglitazone was withdrawn from the market due to idiosyncratic drug toxicity. Rosiglitazone and pioglitazone are still on the market for the treatment of type 2 diabetes. The authors present data from a gene expression screen that compares the impact these three compounds have in rats, in rat hepatocytes, and in the clone 9 rat liver cell line. The authors monitored the changes in expression in multiple genes, including those related to xenobiotic metabolism, proliferation, DNA damage, oxidative stress, apoptosis, and inflammation. Compared to the other two compounds, troglitazone had a significant impact on many of the pathways monitored in vitro although no major perturbation was detected in vivo. The changes detected predict not only general toxicity but potential mechanisms of toxicity. Based on gene expression analysis, the authors propose there is not just one but multiple ways troglitazone could be toxic, depending on a patient's environment and genetic makeup, including immune response-related toxicity.
Vansant
Gordon
G
Althea Technologies, Inc., San Diego, California 92121, USA. gvansant@altheatech.com
Pezzoli
Patrick
P
Saiz
Robert
R
Birch
Aaron
A
Duffy
Chris
C
Ferre
Francois
F
Monforte
Joseph
J
D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D002839:Chromans / Q000633:toxicity*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology / Q000633:toxicity*; D000077205:Pioglitazone; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000494:pharmacology / Q000633:toxicity*; D000077288:Troglitazone
D002839:Chromans; D007004:Hypoglycemic Agents; D045162:Thiazolidinediones; D000077154:Rosiglitazone; D000077288:Troglitazone; D000077205:Pioglitazone