title: Solamargine induces apoptosis and sensitizes breast cancer cells to cisplatin.
abstract: Solamargine (SM), a major steroidal alkaloid glycoside, was purified from Solanum incanum plant. SM exhibited the most cytotoxic effect comparing with that of cisplatin (cDDP), methotrexate (MTX), 5-fluorouracil (5-FU), epirubicin (EPI) and cyclophosphamide (CP) against human breast cancer cells. In this study, SM induces apoptosis of the breast cancer cells and the mechanism was characterized. SM up-regulated the expressions of external death receptors, such as tumor necrosis factor receptor I (TNFR-I), Fas receptor (Fas), TNFR-I-associated death domain (TRADD), and Fas-associated death domain (FADD). SM also enhanced the intrinsic ratio of Bax to Bcl-2 by up-regulating Bax and down-regulating Bcl-2 and Bcl-xL expressions. These effects resulted in the release of mitochondrial cytochrome c and activation of caspase-8, -9 and -3 in the cells, indicating that SM triggered extrinsic and intrinsic apoptotic pathways of breast cancer cells. Similar to function way of SM, cDDP causes cancer cell apoptosis though caspase-8/caspase-3 and Bax/cytochrome c pathways, but the resistance to cDDP is correlated with Bcl-2 and Bcl-xL overexpression. However, the overexpression of Bcl-2 and Bcl-xL can be broken through by SM. The combined treatment of SM and cDDP significantly reduced Bcl-2 and Bcl-xL expressions, and enhanced Bax, cytochrome c, caspase-9 and -3 expressions in breast cancer cells. Thus, the combined use of SM and cDDP may be effective in cDDP-resistant breast cancer.
authors.affiliation: Department of Biochemistry, School of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
authors.forename: L Y
authors.initials: LY
authors.lastname: Shiu
authors.forename: L C
authors.initials: LC
authors.lastname: Chang
authors.forename: C H
authors.initials: CH
authors.lastname: Liang
authors.forename: Y S
authors.initials: YS
authors.lastname: Huang
authors.forename: H M
authors.initials: HM
authors.lastname: Sheu
authors.forename: K W
authors.initials: KW
authors.lastname: Kuo
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy*; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D015536:Down-Regulation; D004357:Drug Synergism; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D020128:Inhibitory Concentration 50; D015398:Signal Transduction; D012991:Solanaceous Alkaloids / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; D012991:Solanaceous Alkaloids; C026609:beta-solamarine; D002945:Cisplatin