[Effect of Tauroursodeoxycholic acid on cytochrome C-mediated apoptosis in HepG2 cells].
OBJECTIVE
To investigate the effect of Tauroursodeoxycholic acid (TUDCA) on Taurodeoxycholic acid (TDCA)-induced HepG2 cell apoptosis and to clarify the molecular mechanism of its anti-apoptosis effect of TUDCA.


METHODS
Morphologic evaluation of apoptotic cells was performed by Hoechst 33258 staining and electron microscope. DNA fragment was detected by electrophoresis on 1.5% agarose gels. Apoptosis rate was measured by flow cytometry using PI dye. Following incubation of HepG2 cells either with TDCA alone, or coincubation with TUDCA and TDCA, the releasing level of cytochrome c from mitochondria into cytosol was determined by western blot, also the activity of caspase-3, 8, 9.


RESULTS
Incubating the cells with 400 micromol/L TDCA for 12 h induced the cells apoptosis significantly. The apoptotic rate decreased from 50.35% +/- 2.20% to 13.78% +/- 0.84% after coincubation with TUDCA, and this anti-apoptotic effect of TUDCA was confirmed by morphological and DNA ladder detection. TUDCA significantly inhibited the release of cytochrome C from mitochondria into cytosol, and the activity of caspase-9, 3 (t > or = 13.00, P < 0.01), especially at 12 h, caspase-3 activity decreased by 54.9% (t = 16.88, P < 0.01) and 52.5%, however it had no obvious effect on the activity of caspase-8 (t = 1.94, P > 0.05).


CONCLUSIONS
TUDCA prevents HepG2 cells apoptosis induced by TDCA through modulating mitochondrial membrane stability, inhibiting the release of cytochrome c and the activation of procaspase-9 and 3. Anti-apoptotic mechanism of TUDCA may be considered to be one of the most important reasons that TUDCA exerts significant efficacy in the treatment of cholestatic liver diseases.
Xie
Qing
Q
Department of Infectious Diseases, Ruijin Hospital, Shanghai Second Medical University, Shanghai 200025, China.
Li
Guang-ming
GM
Zhou
Xia-qiu
XQ
Liao
Dan
D
Yu
Hong
H
Guo
Qing
Q
D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000473:pathology; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D045304:Cytochromes c / Q000494:pharmacology*; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D013655:Taurochenodeoxycholic Acid / Q000494:pharmacology*; D013657:Taurodeoxycholic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D013655:Taurochenodeoxycholic Acid; D013657:Taurodeoxycholic Acid; C031655:ursodoxicoltaurine; D045304:Cytochromes c; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases