title: Saikosaponin D disrupts platelet-derived growth factor-β receptor/p38 pathway leading to mitochondrial apoptosis in human LO2 hepatocyte cells: a potential mechanism of hepatotoxicity.
abstract: Herbal hepatotoxicity has been increasingly reported in clinical context, but the underlying mechanisms are poorly understood. Saikosaponin D (SSD) is a major component of saikosaponins isolated from Bupleurum falactum, a herb that has been linked to hepatotoxicity. Our current study was to examine the toxic effect of SSD on human hepatocyte LO2 cells and explore the possible mechanism. The results demonstrated that SSD reduced cell viability and led to dramatic morphological alterations in LO2 cells. Hoechst staining and flow cytometry analyses showed that SSD stimulated hepatocyte apoptosis. SSD-treated cells exhibited apparent nuclear condensation and fragmentation, and the apoptotic cells were increased by SSD dose-dependently. Subsequent experiments showed that SSD decreased mitochondrial membrane potential and downregulated Bcl-2 but upregulated Bax. Moreover, caspase-9 and caspase-3 were activated in SSD-treated LO2 cells. These data consistently indicated that SSD stimulated mitochondrial apoptosis in hepatocytes. Mechanistic investigations showed that SSD disrupted p38 signaling and that p38 specific inhibitor SB203580 mimicked the pro-apoptotic effect of SSD. In addition, platelet-derived growth factor-β receptor (PDGF-βR) blocker imatinib reduced p38 phosphorylation and also mimicked the pro-apoptotic effect of SSD in LO2 cells. These data collectively indicated that SSD induced apoptosis by interrupting PDGF-βR/p38 pathway in LO2 hepatocytes.
authors.affiliation: Department of Pharmacology, College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Desong
authors.initials: D
authors.lastname: Kong
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Zhu
authors.forename: Wenxing
authors.initials: W
authors.lastname: Chen
authors.forename: Aiyun
authors.initials: A
authors.lastname: Wang
authors.forename: Shizhong
authors.initials: S
authors.lastname: Zheng
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D015394:Molecular Structure; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000494:pharmacology; D017479:Receptors, Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012503:Saponins / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D047428:Protein Kinase Inhibitors; D012503:Saponins; D009828:Oleanolic Acid; D017479:Receptors, Platelet-Derived Growth Factor; D048051:p38 Mitogen-Activated Protein Kinases; C025759:saikosaponin D
keywords: 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium; APAP; DMEM; DMSO; Dulbecco’s modified eagle medium; FBS; Hepatotoxicity; MAPK; MTP; MTS; Mitochondrial apoptosis; N-acetyl-p-aminophenol; PDGF-βR; Platelet-derived growth factor-β receptor; SSD; Saikosaponin D; dimethylsulfoxide; fetal bovine serum; mitochondrial transmembrane potential; mitogen-activated protein kinase; p38; platelet-derived growth factor-β receptor