Wogonin triggers apoptosis in human osteosarcoma U-2 OS cells through the endoplasmic reticulum stress, mitochondrial dysfunction and caspase-3-dependent signaling pathways

Abstract

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 Ca 2+ 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 Ca 2+ , 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.

Activation of endoplasmic reticulum stress and the extrinsic apoptotic pathway in human lung cancer cells by the new synthetic flavonoid, LZ-205

“…We speculated that there must be a pathway independent of ROS and ER stress involved in LZ-205-induced apoptosis. Previous studies found that Wogonin induces apoptosis through the Fas-related extrinsic signaling pathways in human osteosarcoma U-2 OS cells [18] and human leukemia CEM T cells [31, 32]. In the present study, LZ-205 also increased Fas and FasL expression and subsequently activated caspase 8.…”

“…Wogonin induces apoptosis in hepatocellular carcinoma cells through the caspase 3 pathway and alternative expression of p21 protein [15–17] or by activating other pathways [18, 19]. In addition, many wogonin derivatives have been reported to possess potential anti-tumor properties, such as LYG-202, LW-214, etc.…”

Triggering Apoptotic Death of Human Malignant Melanoma A375.S2 Cells by Bufalin: Involvement of Caspase Cascade-Dependent and Independent Mitochondrial Signaling Pathways

“…A375.S2 cells at a density of 2 × 10 5 cells/well were placed onto 6-well plates and treated with bufalin (0, 150, 250, 350, 450, and 550 nM) for 24 and 48 h before cells from each treatment were isolated for DAPI staining as described previously [31, 32]. After staining, the cells were examined and photographed using a fluorescence microscope at 200x magnification [33, 34].…”

Activations of Both Extrinsic and Intrinsic Pathways in HCT 116 Human Colorectal Cancer Cells Contribute to Apoptosis through p53-Mediated ATM/Fas Signaling byEmilia sonchifoliaExtract, a Folklore Medicinal Plant

“…Cells were harvested from each treatment, resuspended in 500  μ L of H 2 DCF-DA (5  μ M) for ROS (hydrogen peroxide; H 2 O 2 ) at 37°C for 30 min. Consequently, cells were immediately analyzed by flow cytometry as described elsewhere [28, 29]. All fluorescence intensities were obtained from the mean intensity of the histogram constructed from approximately 10,000 cells using BD CellQuest Pro software.…”