Involvement of HSP70 in the protection of bicyclol on apoptosis of HepG2 cells intoxicated by d-galactosamine.
Heat shock proteins (HSPs), the best known endogenous factors, play important roles in the cytoprotection and repair of cells and tissues against the harmful effects of stress and insults. In this study, RNAi technology was used to identify whether HSP70 was involved in the protection of bicyclol against d-galactosamine (d-GaIN)-induced apoptosis in HepG2 cells. As a result, bicyclol induced HSP70 in a time- and dose-dependent manner in HepG2 cells. Bicyclol markedly alleviated apoptosis and caspase-3 activity in HepG2 cells intoxicated by d-GaIN. The degradation of inhibitory kappa B, phosphorylation of inhibitory kappa B kinase, nuclear factor kappa B (NF-kappaB) nuclear translocation, and DNA-binding activity were all inhibited by bicyclol in HepG2 cells intoxicated by d-GaIN. In addition, bicyclol decreased the nitric oxide production and inducible nitric oxide synthase (iNOS) expression. The inhibitory effects of bicyclol on all the above biomarkers were attenuated when the HSP70 gene was silenced accordingly. Our data also showed that MG132 (inhibitor of NF-kappaB) and NG-nitro-l-arginine methyl ester (inhibitor of iNOS) inhibited hepatocyte apoptosis induced by d-GaIN. These in vitro results suggested that HSP70 partially contributed to the hepatoprotection of bicyclol through suppressing the NF-kappaB-iNOS pathway.
Bao
Xiu-Qi
XQ
Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Liu
Geng-Tao
GT
D017209:Apoptosis / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005688:Galactosamine / Q000737:chemistry / Q000494:pharmacology*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015394:Molecular Structure; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D013237:Stereoisomerism
D001713:Biphenyl Compounds; D018840:HSP70 Heat-Shock Proteins; D016328:NF-kappa B; D005688:Galactosamine; C477843:bicyclol; D052247:Nitric Oxide Synthase Type II; D053148:Caspase 3; D019331:NG-Nitroarginine Methyl Ester