Oridonin induced apoptosis through Akt and MAPKs signaling pathways in human osteosarcoma cells

Department of Orthopedic Surgery, First Affiliated Hospital, 74 Zhongshan 2 Road, Guangzhou, Guangdong 510080, China.
Cancer biology & therapy (Impact Factor: 3.07). 03/2007; 6(2):261-8. DOI: 10.4161/cbt.6.2.3621
Source: PubMed


Previous studies have shown that oridonin, a diterpenoid isolated from Rabdosia rubescens, was able to inhibit proliferation and induce apoptosis in several cell types. But the mechanisms remain poorly understood. In this study, we investigated the apoptosis-inducing effect and mechanisms of action of oridonin in human osteosarcoma cells. Our results demonstrated that oridonin induced concentration- and time-dependent suppression of proliferation and activation of apoptosis in U2OS, MG63 and SaOS-2 osteosarcoma cell lines. Oridonin induced the release of cytochrome c accompanied by activation of caspase-9, caspase-3 and cleavage of poly(ADP-ribose) polymerase (PARP). These events were all inhibited by z-VAD-fmk, a universal inhibitor of caspases. Oridonin treatment dephosphorylated constitutively active AKT, FOXO transcription factor, and glycogen synthase kinase 3 (GSK3). In addition, oridonin decreased the phosphorylation of ERK and increased the phosphorylation of p38 MAPK and JNK. Furthermore, oridonin treatment down-regulated the expression of the inhibitor of apoptosis protein(IAP) in osteosarcoma cells. All together, our results suggested that oridonin is able to inactivate Akt and ERK and activate p38 MAPK and JNK signalling pathways in osteosarcoma cells causing the suppression of proliferation and induction of mitochondria- and caspase-dependent apoptosis.

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Available from: Jia-Guo Zhou, Jun 26, 2014
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    • "In recent years, oridonin has attracted more attention because it stimulates cell cycle arrest and apoptosis in a wide variety of tumors both in vivo and in vitro. Numerous proteins and pathways have been shown to regulate oridonin-mediated apoptosis, including the cysteine-dependent aspartate-specific proteases (caspase) family, the Bcl-2 family, the mitogen-activated protein kinase (MAPK) family, the nuclear factor-kappaB (NF-κB), p53, and phosphoinositide 3-kinase (PI3K) signal transduction pathways [12,13,15,16]. However, systematic studies on how oridonin affects gallbladder cancer have not been reported. "
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    ABSTRACT: Gallbladder cancer is the most frequent malignancy of the bile duct with high aggressive and extremely poor prognosis. The main objective of the paper was to investigate the inhibitory effects of oridonin, a diterpenoid isolated from Rabdosia rubescens, on gallbladder cancer both in vitro and in vivo and to explore the mechanisms underlying oridonin-induced apoptosis and cell cycle arrest. The anti-tumor activity of oridonin on SGC996 and NOZ cells was assessed by the MTT and colony forming assays. Cell cycle changes were detected by flow cytometric analysis. Apoptosis was detected by annexin V/PI double-staining and Hoechst 33342 staining assays. Loss of mitochondrial membrane potential was observed by Rhodamine 123 staining. The in vivo efficacy of oridonin was evaluated using a NOZ xenograft model in athymic nude mice. The expression of cell cycle- and apoptosis-related proteins in vitro and in vivo was analyzed by western blot analysis. Activation of caspases (caspase-3, -8 and -9) was measured by caspases activity assay. Oridonin induced potent growth inhibition, S-phase arrest, apoptosis, and colony-forming inhibition in SGC996 and NOZ cells in a dose-dependent manner. Intraperitoneal injection of oridonin (5, 10, or 15 mg/kg) for 3 weeks significantly inhibited the growth of NOZ xenografts in athymic nude mice. We demonstrated that oridonin regulated cell cycle-related proteins in response to S-phase arrest by western blot analysis. In contrast, we observed inhibition of NF-kappaB nuclear translocation and an increase Bax/Bcl-2 ratio accompanied by activated caspase-3, caspase-9 and PARP-1 cleavage after treatment with oridonin, which indicate that the mitochondrial pathway is involved in oridonin-mediated apoptosis. Oridonin possesses potent anti-gallbladder cancer activities that correlate with regulation of the mitochondrial pathway, which is critical for apoptosis and S-phase arrest. Therefore, oridonin has potential as a novel anti-tumor therapy for the treatment of gallbladder cancer.
    Full-text · Article · Mar 2014 · BMC Cancer
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    • "It has been demonstrated that a number of reagents are able to induce apoptosis on MG63 human osteosarcoma cells (25–27); however, the effect of capsaicin on MG63 cells has remained unclear. Capsaicin, the main pungent ingredient in the genus Capsicum, has long been used in drugs for weight loss and has been studied as an attractive drug for cancer treatment, as an agent that induces apoptosis in various cell types in vitro(28–31). "
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    ABSTRACT: Osteosarcoma is the most common malignant bone tumor in children and adolescents. This aggressive cancer mostly occurs in the long bones. Therefore, novel therapeutic approaches, such as biological therapies and gene therapy, are required to efficiently treat osteosarcoma. Capsaicin (trans‑8‑methyl‑N‑vanillyl‑6‑nonenamide) has been demonstrated to inhibit the growth of several types of cancer cells and a number of studies have shown that osteosarcoma may be vulnerable to biological therapies. However, little is known regarding the therapeutic effects of capsaicin on osteosarcoma. This study investigated the effects of capsaicin on MG63 human osteosarcoma cells, in addition to elucidating the regulatory signaling pathways underlying the effects of capsaicin, the caspase cascade and the antioxidant enzyme system. The MG63 cell line was treated with various concentrations of capsaicin. Cells were analyzed using MTT and flow cytometry, and the presence of DNA fragmentation was evaluated using TUNEL assay. Results showed capsaicin induced apoptosis in MG63 cells. Thus, capsaicin exhibited an anticancer effect in osteosarcoma cells.
    Full-text · Article · Dec 2013 · Molecular Medicine Reports
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    • "There are two explanations for this contradiction. First, ORI is able to inactivate Class I PI3K/Akt pathway23, 24. The blockade of Class I PI3K/PKB pathway weakens the positive effect of 3-MA on autophagy. "
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    ABSTRACT: Oridonin (ORI) could inhibit the proliferation and induce apoptosis in various cancer cell lines. However, the mechanism is not fully understood. Human prostate cancer (HPC) cells were cultured in vitro and cell viability was detected by the CCK-8 assay. The ultrastructure changes were observed under transmission electron microscope (TEM). Chemical staining with acridine orange (AO), MDC or DAPI was used to detect acidic vesicular organelles (AVOs) and alternation of DNA. Expression of LC3 and P21 was detected by Western Blot. Apoptotic rates and cell cycle arrest were detected by FACS. Our study demonstrated that after ORI treatment, the proliferations of human prostate cancer (HPC) cell lines PC-3 and LNCaP were inhibited in a concentration and time-dependent manner. ORI induced cell cycle arrest at the G2/M phase. A large number of autophagosomes with double-membrane structure and acidic vesicular organelles (AVOs) were detected in the cytoplasm of HPC cells treated with ORI for 24 hours. ORI resulted in the conversion of LC3-I to LC3-II and recruitment of LC3-II to the autophagosomal membranes. Autophagy inhibitor 3-methyladenine (3-MA) reduced AVOs formation and inhibited LC3-I to LC3-II conversion. At 48 h, DNA fragmentation, chromatin condensation and disappearance of surface microvilli were detected in ORI-treated cells. ORI induced a significant increase in the number of apoptotic cells (PC-3: 5.4% to 27.0%, LNCaP: 5.3% to 31.0%). Promoting autophagy by nutrient starvation increased cell viability, while inhibition of autophagy by 3-MA promoted cell death. The expression of P21 was increased by ORI, which could be completely reversed by the inhibition of autophagy. Our findings indicated that autophagy occurred before the onset of apoptosis and protected cancer cells in ORI-treated HPC cells. P21 was involved in ORI-induced autophagy and apoptosis. Our results provide an experimental basis for understand the anti-tumor mechanism of ORI as treatment for prostate cancer.
    Preview · Article · Jun 2012 · International journal of biological sciences
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