Signal Transduction Mechanism Of Ginsenoside Rh2-induced HL-60 Apoptosis

Ginsenoside Rh2, a dammarane saponin derived from Panax ginseng, has been identified as the major component responsible for ginseng's antitumor action. Accumulating evidences showed that G-Rh2 possesses antitumor activity in vivo and in vitro, however, signal transduction mechanism underlying the antitumor effect of G-Rh2, especially its non-organ specific antitumor effects, have not been elucidated. In this study, using tumor oligonucleotide microarray, and further combining with bioinformatics methods, we explored the gene expression profile of G-Rh2-treated human acute myeloid leukemia HL-60 cell line, and characterized the signal pathway and molecular interacting network,preliminarily elucidated signal transduction mechanism underlying antitumor activity of G-Rh2.MTT,Flowmetry and DNA fragmentation assays were used to determine the antitumor effects of G-Rh2 on HL-60 cells in vitro, afterwards genechip and The Pathway analysis of gene expression profile was performed by bioinformatics soft GenMAPP. Follow-up comfirmation of key differently expressed molecule was conducted by RT-PCR and Western blotting. Finally, the neutralizing antibody of key differently expressed molecule was utilized to dissect role played by key differentially expressed molecule.Ginsenoside Rh2 can inhibit the proliferation of HL-60 cells, significantly arrest the cell cycle in G1 phase and markedly induce apoptosis. The gene expression profile of HL-60 shows that 76 genes were differentially expressed, 16 of 480 genes up-regulated and 60 genes down-regulated. Compared with control, the most highly expressed was tumor necrosis factor TNFα. The differentially expressed genes were involved in the proliferative inhibition, differentiation and apoptosis of HL-60 cells. The up-regulation of TNFαexpression was confirmed by RT-PCR and Western blotting in time-dependent manner. In addition, The neutralizing antibody of TNFαcomfirmed the up-regulation of TNFαwas involved in the inhibitory effect of G-Rh2 on HL-60 cells and also suggested that TNFα. Furthermore, the antitumor effect of on HL-60 cells may be mediated through TNFαapoptotic pathway.G-Rh2 can significantly inhibit proliferation, arrest cell cycle G1 phase progression and induce apoptosis in HL-60 cells; The modulated gene by G-Rh2 in HL-60 cells were mostly implicated in cell cycle control of G1 phase, differentiation and apoptosis,and the overexpression of TNFαinduced by G-Rh2 in HL-60 was one of master signal transduction pathway mediating G-Rh2 antitumor effects. Overexpression of TNFαG-Rh2-induced may also be a key target protein and signal transduction molecule mediated G-Rh2 exerting its non-organ specific antitumor effects.