title: p53-dependent Fas expression is critical for Ginsenoside Rh2 triggered caspase-8 activation in HeLa cells.
abstract: We have recently reported that Ginsenoside Rh2 (G-Rh2) induces the activation of two initiator caspases, caspase-8 and caspase-9 in human cancer cells. However, the molecular mechanism of its death-inducing function remains unclear. Here we show that G-Rh2 stimulated the activation of both caspase-8 and caspase-9 simultaneously in HeLa cells. Under G-Rh2 treatment, membrane death receptors Fas and TNFR1 are remarkably upregulated. However, the induced expression of Fas but not TNFR1 was contributed to the apoptosis process. Moreover, significant increases in Fas expression and caspase-8 activity temporally coincided with an increase in p53 expression in p53-non-mutated HeLa and SK-HEP-1 cells upon G-Rh2 treatment. In contrast, Fas expression and caspase-8 activity remained constant with G-Rh2 treatment in p53-mutated SW480 and PC-3 cells. In addition, siRNA-mediated knockdown of p53 diminished G-Rh2-induced Fas expression and caspase-8 activation. These results indicated that G-Rh2-triggered extrinsic apoptosis relies on p53-mediated Fas over-expression. In the intrinsic apoptotic pathway, G-Rh2 induced strong and immediate translocation of cytosolic BAK and BAX to the mitochondria, mitochondrial cytochrome c release, and subsequent caspase-9 activation both in HeLa and in SW480 cells. p53-mediated Fas expression and subsequent downstream caspase-8 activation as well as p53-independent caspase-9 activation all contribute to the activation of the downstream effector caspase-3/-7, leading to tumor cell death. Taken together, we suggest that G-Rh2 induces cancer cell apoptosis in a multi-path manner and is therefore a promising candidate for anti-tumor drug development.
authors.affiliation: Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, College of Life Science, Jilin University, Changchun, 130012, China.
authors.forename: Xiao-Xi
authors.initials: XX
authors.lastname: Guo
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
authors.forename: Dan
authors.initials: D
authors.lastname: Jiang
authors.forename: Ying-Jia
authors.initials: YJ
authors.lastname: Lin
authors.forename: Feng-Xie
authors.initials: FX
authors.lastname: Jin
authors.forename: Seung-Ki
authors.initials: SK
authors.lastname: Lee
authors.forename: Ying-Hua
authors.initials: YH
authors.lastname: Jin
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism*; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D036145:Ginsenosides / Q000737:chemistry / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D053218:Receptors, Death Domain / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism*
chemical_list: C491901:FAS protein, human; D036145:Ginsenosides; D053218:Receptors, Death Domain; D047888:Receptors, Tumor Necrosis Factor, Type I; D016159:Tumor Suppressor Protein p53; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D019014:fas Receptor; C055305:ginsenoside Rh2; D045304:Cytochromes c; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9