Hepatocytes isolated from preneoplastic rat livers are resistant to ethacrynic acid cytotoxicity

PARODY, JUAN PABLO; ALVAREZ, MARIA DE LUJAN; QUIROGA, ARIEL DARIO; RONCO, MARIA TERESA; FRANCES, DANIEL ELEAZAR ANTONIO; CARNOVALE, CRISTINA ESTER; CARRILLO, MARÍA CRISTINA

ARCHIVES OF TOXICOLOGY.

Año: 2007 vol. 81 p. 565 - 573

0340-5761

Glutathione S-transferases (GSTs) are involved in the detoxiWcation 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 eVects of EA since viability and cellular integrity values were signiWcantly higher than control. Initial levels of thiobarbituric acid reactive substances (TBARS) in IP hepatocytes were signiWcantly 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 Wvefold 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. 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.S-transferases (GSTs) are involved in the detoxiWcation 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 eVects of EA since viability and cellular integrity values were signiWcantly higher than control. Initial levels of thiobarbituric acid reactive substances (TBARS) in IP hepatocytes were signiWcantly 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 Wvefold 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. 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.Wcation 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 eVects of EA since viability and cellular integrity values were signiWcantly higher than control. Initial levels of thiobarbituric acid reactive substances (TBARS) in IP hepatocytes were signiWcantly 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 Wvefold 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. 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.Vects of EA since viability and cellular integrity values were signiWcantly higher than control. Initial levels of thiobarbituric acid reactive substances (TBARS) in IP hepatocytes were signiWcantly 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 Wvefold 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. 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.Wcantly higher than control. Initial levels of thiobarbituric acid reactive substances (TBARS) in IP hepatocytes were signiWcantly 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 Wvefold 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. 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.Wcantly 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 Wvefold 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. 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.Wvefold 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. 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.