Hepatocytes isolated from preneoplastic rat livers are resistant to ethacrynic acid cytotoxicity.
Glutathione S-transferases (GSTs) are involved in the detoxification of xenobiotics, such as several cytostatic drugs, through conjugation with glutathione (GSH). Pi class GST (GST P) liver expression is associated with preneoplastic and neoplastic development and contributes with the drug-resistance phenotype. Ethacrynic acid (EA) is an inhibitor of rat and human GSTs. In addition, causes lipid peroxidation in isolated rat hepatocytes. Therefore, we decided to evaluate the role of the GST/GSH system in isolated hepatocytes from preneoplastic rat livers (IP) in the presence of EA and determine the cytotoxicity of the drug. Our results showed a resistance to the toxic effects of EA since viability and cellular integrity values were significantly higher than control. Initial levels of thiobarbituric acid reactive substances (TBARS) in IP hepatocytes were significantly higher than control and the presence of EA did not change TBARS levels. A diminution in intracellular total GSH was observed by treating with EA isolated hepatocytes from both groups. However, the initial total GSH levels were higher in IP hepatocytes than in control. Immunoblotting analysis showed the presence of GST P in IP animals only. Although alpha and mu class isoenzymes levels were decreased in IP hepatocytes, total GST activity was 1.5-fold higher than in control. In addition, multidrug-resistance protein 2 (Mrp2) showed fivefold decreased levels in IP hepatocytes. In conclusion, increased total GSH, decreased Mrp2 levels and the presence of GST P could be critical factors involved in the resistance of IP hepatocytes to the toxicity of EA.
Parody
Juan Pablo
JP
Facultad de Ciencias Bioquímicas y Farmacéuticas (UNR), Instituto de Fisiología Experimental (IFISE-CONICET), Suipacha 570, 2000 Rosario, Santa Fe, Argentina.
Alvarez
María de Luján
Mde L
Quiroga
Ariel
A
Ronco
María Teresa
MT
Francés
Daniel
D
Carnovale
Cristina
C
Carrillo
María Cristina
MC
D015073:2-Acetylaminofluorene / Q000633:toxicity; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000477:Alkylating Agents / Q000633:toxicity; D000818:Animals; D002273:Carcinogens / Q000633:toxicity; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004052:Diethylnitrosamine / Q000633:toxicity; D004232:Diuretics / Q000633:toxicity*; D004351:Drug Resistance; D004976:Ethacrynic Acid / Q000633:toxicity*; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008113:Liver Neoplasms / Q000139:chemically induced / Q000378:metabolism*; D008297:Male; D011230:Precancerous Conditions / Q000139:chemically induced / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D018528:ATP-Binding Cassette Transporters; C423013:Abcc2 protein, rat; D000477:Alkylating Agents; D002273:Carcinogens; D004232:Diuretics; D017392:Thiobarbituric Acid Reactive Substances; D004052:Diethylnitrosamine; D015073:2-Acetylaminofluorene; D007770:L-Lactate Dehydrogenase; D005982:Glutathione Transferase; D005978:Glutathione; D004976:Ethacrynic Acid