A non-toxic heat shock protein 70 inducer, geranylgeranylacetone, suppresses apoptosis of cultured rat hepatocytes caused by hydrogen peroxide and ethanol

Background/Aims: A stress-inducible heat shock protein 70 (HSP70) is one of the best-known endogenous factors protecting cell injury under various pat hological conditions. The aim of this study was to examine anti-apoptotic a ctions of a non-toxic HSP70 inducer, geranylgeranylacetone (GGA), on hepato cytes exposed to hydrogen peroxide (H2O2) or ethanol. Methods: Primary cultures of rat hepatocytes were treated with different co ncentrations of GGA and exposed to 0.5 mM H2O2 or 100 mM ethanol. The heat shock response was assessed by measuring the activation of heat shock facto r 1 (HSF1), HSP70 mRNA expression, and accumulations of HSP70, HSP90, and H SP27. Apoptosis was evaluated by DNA fragmentation. Results: Pretreatment with 1 muM GGA for 2 h enhanced nuclear translocation and phosphorylation of HSF1, HSF1-DNA binding, HSP70 mRNA expression, and its accumulation, when the cells were exposed to H2O2 Or ethanol. In associ ation with this accelerated response, GGA suppressed the insult-induced act ivation of c-Jun N-terminal kinases, caspase 9, and caspase 3-like protease s, leading to significant inhibition of apoptosis. Conclusions: GGA exerted anti-apoptotic actions, at least in part, by primi ng hepatocytes for enhanced HSP70 induction. Our results suggest that GGA m ay have a potential benefit for the treatment of alcoholic and ischemia-rep erfusion liver injuries. (C) 2001 European Association for the Study of the Liver. Published by Elsevier Science B.V. All rights reserved.