title: Gypenosides induce apoptosis by ca2+ overload mediated by endoplasmic-reticulum and store-operated ca2+ channels in human hepatoma cells.
abstract: Gypenosides (Gyps) are triterpenoid saponins contained in an extract from Gynostemma pentaphyllum Makino and reported to induce apoptosis in human hepatoma cells through Ca(2+)-implicated endoplasmic reticulum (ER) stress and mitochondria-dependent pathways. The mechanism underlying the Gyp-increased intracellular Ca(2+) concentration ([Ca(2+)]i) is unclear. Here, we examined Gyp-induced necrosis and apoptosis in human hepatoma HepG2 cells. Gyp-induced apoptotic cell death was accompanied by a sustained increase in [Ca(2+)]i level. Gyp-increased [Ca(2+)]i level was partly inhibited by removal of extracellular Ca(2+) by Ca(2+) chelator EGTA, store-operated Ca(2+) channel (SOC) inhibitor 2- aminoethoxydiphenyl borate (2-APB), and ER Ca(2+)-release-antagonist 3,4,5-trimethoxybenzoic acid 8-(diethylamino) octyl ester (TMB-8). The strongest inhibitory effect was observed with TMB-8. EGTA, 2-APB, and TMB-8 also protected against Gyp-induced apoptosis in HepG2 cells. The combination of 2-APB and TMB-8 almost completely abolished the Gyp-induced Ca(2+) response and apoptosis. In contrast, the sarco/endoplasmic-reticulum-Ca(2+)-ATPase (SERCA) inhibitor thapsigargin slightly elevated Gyp-induced [Ca(2+)]i increase and apoptosis in HepG2 cells. Exposure to 300 μg/mL Gyp for 24 hours upregulated protein levels of inositol 1,4,5-trisphosphate receptor and SOC and downregulated that of SERCA for at least 72 hours. Thus, Gyp-induced increase in [Ca(2+)]i level and consequent apoptosis in HepG2 cells may be mainly due to enhanced Ca(2+) release from ER stores and increased store-operated Ca(2+) entry.
authors.affiliation: 1 Cancer Research Institute, First Affiliated Hospital, China Medical University , Shenyang, People's Republic of China .
authors.forename: Da-Peng
authors.initials: DP
authors.lastname: Sun
authors.forename: Xiao-Xi
authors.initials: XX
authors.lastname: Li
authors.forename: Xin-Li
authors.initials: XL
authors.lastname: Liu
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.forename: Feng-Qi
authors.initials: FQ
authors.lastname: Qiu
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Ping
authors.initials: P
authors.lastname: Ma
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism*; D002470:Cell Survival; D002614:Chelating Agents / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D004533:Egtazic Acid / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D029774:Gynostemma; D056945:Hep G2 Cells; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D009336:Necrosis / Q000139:chemically induced; D010936:Plant Extracts / Q000494:pharmacology; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D001896:Boron Compounds; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D053496:Inositol 1,4,5-Trisphosphate Receptors; D010936:Plant Extracts; C474918:gypenoside; D004533:Egtazic Acid; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D019284:Thapsigargin; C109986:2-aminoethoxydiphenyl borate; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium
keywords: HepG2 cells; calcium ion; cell apoptosis; gypenosides; hepatocellular carcinoma