title: Astragalus saponins induce apoptosis via an ERK-independent NF-kappaB signaling pathway in the human hepatocellular HepG2 cell line.
abstract: Astragalus membranaceus has been used to ameliorate the side effects of anti-neoplastic drugs. We recently reported that total Astragalus saponins (AST) possess anti-tumor properties in human colon cancer cells and tumor xenografts. Nevertheless, the precise mechanism of action has not been fully elucidated. The present study aimed to unveil the anti-carcinogenic potential of AST in HepG2 human hepatocellular carcinoma (HCC) cells and to clarify the signaling pathway. We demonstrated here that AST downregulated expression of the HCC tumor marker alpha-fetoprotein and suppressed HepG2 cell growth by inducing apoptosis. AST also caused caspase activation, poly(ADP-ribose) polymerase (PARP) cleavage, nuclear chromatin condensation, with downregulation of the anti-apoptotic proteins bcl-2 and bcl-xL and decreased nuclear factor-kappa B (NF-kappaB)/DNA-binding activity. Concomitantly, expression of the phosphorylated form of the extracellular signal-regulated protein kinase (ERK) was prominently increased. Nevertheless, pretreatment of ERK inhibitor PD98059 did not attenuate AST-induced PARP cleavage. Taken together, these results exemplify that AST induced growth inhibition and promoted apoptosis in HepG2 cells through modulation of an ERK-independent NF-kappaB signaling pathway.
authors.affiliation: Pharmacology and Toxicology Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, SAR, PR China.
authors.forename: Kathy Ka-wai
authors.initials: KK
authors.lastname: Auyeung
authors.forename: Pui-ching
authors.initials: PC
authors.lastname: Law
authors.forename: Joshua Ka-shun
authors.initials: JK
authors.lastname: Ko
mesh_terms: D017209:Apoptosis; D027883:Astragalus Plant / Q000737:chemistry*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D045744:Cell Line, Tumor; D015536:Down-Regulation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D012503:Saponins / Q000633:toxicity*; D015398:Signal Transduction; D000509:alpha-Fetoproteins / Q000235:genetics / Q000378:metabolism
chemical_list: D016328:NF-kappa B; D012503:Saponins; D000509:alpha-Fetoproteins; D052247:Nitric Oxide Synthase Type II; D048049:Extracellular Signal-Regulated MAP Kinases