The molecular mechanism of gypenosides-induced G1 growth arrest of rat hepatic stellate cells.
OBJECTIVE
Gypenosides, the saponins extract derived from Gynostemma pentaphyllum Makino, have been used for treating hepatitis and cancer in Asia. Our previous study demonstrates that gypenosides inhibit the onset and improve the recovery of liver fibrosis induced by CCl4 in rats. In this study, we used the isolated rat hepatic stellate cells (HSCs) as a model to study the cellular mechanism of gypenosides-inhibited liver fibrosis.


METHODS
Rat HSCs was treated with PDGF, gypenosides or vehicle. Cell viability was assessed by trypan blue staining. Apoptosis and cell cycle were evaluated by flow cytometry. The activation or inhibition of signal molecules was detected by Western blotting.


RESULTS
Our results showed that 500 microg/ml gypenosides decreased PDGF-induced rat HSCs numbers (8750+/-2629 versus 103,000+/-6683, p<0.001, 95% confidence interval) and arrested cells at the G1 phase without the presence of sub-G1 fraction. Analysis of PDGF-induced proliferative molecules including phosphorylation of Akt and p70 S6K, gypenosides inhibited the activation of this signal pathway. Furthermore, gypenosides down-regulated the protein expression of cell cycle G1-specific cyclin D1 and D3.


CONCLUSIONS
Gypenosides inhibited PDGF-induced HSCs proliferation by inhibiting the signal pathway of PDGF-Akt-p70 S6K and down-regulation of cyclin D1 and D3 expression.
Chen
Ming-Ho
MH
Department of Chinese Medicine, Chiayi Christian Hospital, Chiayi, Taiwan.
Chen
Shu-Hsin
SH
Wang
Qwa-Fun
QF
Chen
Jung-Chou
JC
Chang
De-Ching
DC
Hsu
Shih-Lan
SL
Chen
Ching-Hsein
CH
Sheue
Chiou-Rong
CR
Liu
Yi-Wen
YW
D000818:Animals; D017304:Annexin A5 / Q000494:pharmacology; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002469:Cell Separation; D019938:Cyclin D1 / Q000096:biosynthesis / Q000235:genetics; D056743:Cyclin D3; D016213:Cyclins / Q000096:biosynthesis / Q000235:genetics; D005355:Fibrosis; D016193:G1 Phase / Q000187:drug effects*; D029774:Gynostemma / Q000737:chemistry; D022781:Hepatocytes / Q000187:drug effects* / Q000473:pathology; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology; D011208:Powders; D051381:Rats; D017207:Rats, Sprague-Dawley; D017479:Receptors, Platelet-Derived Growth Factor / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects
D017304:Annexin A5; C534698:Ccnd3 protein, rat; D056743:Cyclin D3; D016213:Cyclins; D010936:Plant Extracts; D011208:Powders; C474918:gypenoside; D019938:Cyclin D1; D019869:Phosphatidylinositol 3-Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D020928:Mitogen-Activated Protein Kinases