title: Wogonin triggers apoptosis in human osteosarcoma U-2 OS cells through the endoplasmic reticulum stress, mitochondrial dysfunction and caspase-3-dependent signaling pathways.
abstract: Wogonin (5,7-dihydroxy-8-methoxyflavone) is a flavone constituent of Scutellaria baicalensis with various beneficial biological activities and it has been shown to have tumor therapeutic potential in vitro and in vivo. The purpose of this study was to investigate the effects of wogonin in a human osteosarcoma cell line (U-2 OS). Results showed that a dose- and time-dependent reduction occurred in cell viability after exposure to wogonin in U-2 OS cells. Increasing the levels of reactive oxygen species (ROS) and Ca2+ but decreasing the levels of mitochondrial membrane potential (∆Ψm) were examined in wogonin-treated U-2 OS cells. Flow cytometric assay indicated that wogonin induced sub-G1 phase (apoptosis) and increased caspase-3 activity in examined cells. Wogonin-induced apoptosis in U-2 OS cells was also confirmed by 4',6-diamidino-2-phenylindole (DAPI) staining. Also, results from Western blotting indicated that wogonin increased the levels of Bad, Bax, cytochrome c, cleaved caspase-9, cleaved caspase-3, AIF, Endo G, Fas/CD95, caspase-8, GADD153, GRP78, ATF-6α, calpain 1, calpain 2 and caspase-4 then leading to cell apoptosis. In conclusion, wogonin induced ROS production and intracellular Ca2+, and altered the levels of anti- (Bcl-2) and pro- (Bad and Bax) apoptotic proteins. Wogonin-induced apoptosis in U-2 OS cells was through the activation of caspase-3. In conclusion, these are the first findings to show wogonin-induced cytotoxic effects through induction of apoptotic cell death and ER stress in U-2 OS cells. The potent in vitro antitumor activities suggest that wogonin could be developed for the treatment of human osteosarcoma in the future.
authors.affiliation: Department of Chinese Medicine, Fong-Yuan Hospital, Executive Yuan, Taichung 420, Taiwan, ROC.
authors.forename: Chin-Chung
authors.initials: CC
authors.lastname: Lin
authors.forename: Chao-Lin
authors.initials: CL
authors.lastname: Kuo
authors.forename: Mau-Hwa
authors.initials: MH
authors.lastname: Lee
authors.forename: Kuang-Chi
authors.initials: KC
authors.lastname: Lai
authors.forename: Jing-Pin
authors.initials: JP
authors.lastname: Lin
authors.forename: Jai-Sing
authors.initials: JS
authors.lastname: Yang
authors.forename: Chun-Shu
authors.initials: CS
authors.lastname: Yu
authors.forename: Chi-Cheng
authors.initials: CC
authors.lastname: Lu
authors.forename: Jo-Hua
authors.initials: JH
authors.lastname: Chiang
authors.forename: Fu-Shin
authors.initials: FS
authors.lastname: Chueh
authors.forename: Jing-Gung
authors.initials: JG
authors.lastname: Chung
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D044950:Flavanones / Q000494:pharmacology*; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000378:metabolism*; D008954:Models, Biological; D012516:Osteosarcoma / Q000503:physiopathology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D004365:Drugs, Chinese Herbal; D000091342:Endoplasmic Reticulum Chaperone BiP; D044950:Flavanones; C000717247:HSPA5 protein, human; D017382:Reactive Oxygen Species; D053148:Caspase 3; C085514:wogonin; D002118:Calcium