Bicyclol protects HepG2 cells against D-galactosamine-induced apoptosis through inducing heat shock protein 27 and mitochondria associated pathway.
OBJECTIVE
To study the inducing effect of bicyclol on heat shock protein 27 (HSP27) and its role on anti-apoptosis in HepG2 cells intoxicated with D-galactosamine (D-GaIN).


METHODS
HepG2 cells were treated with various concentrations of bicyclol and then subjected to D-GaIN intoxication. Apoptosis was assayed by hoechst 33258 staining and flow cytometry analysis. HSP27, cytochrome c, apoptosis inducing factor (AIF) and c-Jun N-terminal kinase (JNK) were assayed by Western blot. Heat shock factor 1 (HSF1) was determined by electrophoretic mobility shift assay and the interactions of HSP27 with cytochrome c and AIF were detected by co-immunoprecipitation.


RESULTS
The results showed that bicyclol induced HSP27 protein and mRNA expression in HepG2 cells in both time- and dose-dependent manners (the maximal response: 1.23 fold increase at 100 micromol/L). Bicyclol treatment stimulated HSF1 activation and increased the HSF1-HSE binding activity (the maximal response: 2.1 fold increase at 100 micromol/L). This inducing effect of bicyclol on HSP27 and HSF1 was markedly blocked by quercetin. Pretreatment of the cells with bicyclol markedly attenuated D-GaIN-induced apoptosis and the release of cytochrome c and AIF from mitochondria. The induced HSP27 by bicyclol suppressed the activity of caspase-3 and the phosphorylation of JNK caused by D-GaIN in HepG2 cells. All the above effect of bicyclol against D-GaIN-induced hepatocytes apoptosis were significantly reversed by quercetin.


CONCLUSIONS
HSP27 is involved in the anti-hepatocytes apoptosis of bicyclol, and this effect of bicyclol-induced HSP27 is mainly through inhibition of mitochondria and JNK apoptotic pathways.
Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Xiu-qi
XQ
Bao
Geng-tao
GT
Liu
D017209:Apoptosis / Q000187:drug effects*; D001483:Base Sequence; D001713:Biphenyl Compounds / Q000494:pharmacology*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D017931:DNA Primers; D024202:Electrophoretic Mobility Shift Assay; D005434:Flow Cytometry; D005688:Galactosamine / Q000494:pharmacology*; D055551:HSP27 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism
D001713:Biphenyl Compounds; D017931:DNA Primers; D055551:HSP27 Heat-Shock Proteins; D005688:Galactosamine; C477843:bicyclol