Oridonin induces apoptosis of HeLa cells via altering expression of Bcl-2/Bax and activating caspase-3/ICAD pathway.
(1/8)
AIM: To study the mechanisms by which oridonin inhibited HeLa cell growth in vitro. METHODS: Viability of oridonin-induced HeLa cells was measured by MTT assay. Apoptotic cells with condensed nuclei were visualized by phase contrast microscopy. Nucleosomal DNA fragmentation was assayed by agarose gel electrophoresis. Caspase activity was assayed using fluorometric protease assay. ICAD, Bcl-2, and Bax proteins expression were detected by Western blot analysis. RESULTS: Oridonin induced oligonucleosomal fragmentation of DNA and increased caspase-3 activity, on the other hand, reduced the expression of inhibitor of caspase-3-activated DNase (ICAD), a caspase-3 substrate, at 12 h in HeLa cells. Oridonin-induced DNA fragmentation, caspase-3 activation and down-regulation of ICAD expression were effectively inhibited by a caspase-3 inhibitor, z-DEVD-fmk (z-Asp-Glu-Val-Asp-fmk). However, pretreatment with an inhibitor of poly (ADP-ribose) polymerase (PARP), 3, 4-dihydro-5-[4-(1-piperidinyl)butoxy]-1(2H)-isoquinolinone (DPQ), did not suppress oridonin-induced HeLa cell death. In addition, oridonin-induced apoptosis was associated with an increase in the expression of the apoptosis inducer Bax, and a significant reduction in expression of the apoptosis suppressor Bcl-2 in mitochondria. CONCLUSION: Oridonin induces HeLa cells apoptosis by altering balance of Bcl-2 and Bax protein expression and activation of caspase-3/ICAD pathway. (+info)
Oridonin induces a caspase-independent but mitochondria- and MAPK-dependent cell death in the murine fibrosarcoma cell line L929.
(2/8)
Oridonin, an active component isolated from Rabdosia rubescences, has been reported to exhibit antitumor effects, but little is known about its molecular mechanisms of action. In this study, the growth-inhibitory activity of oridonin for L929 cells is in time- and dose-dependent manner. After treatment with various concentrations of oridonin for 12 h, the majority of L929 cells underwent apoptosis as measured by an LDH activity-based assay. Although apoptotic bodies were observed in oridonin-treated L929 cells, DNA fragmentation as a hallmark of apoptosis was not found. The pan-caspase inhibitor, z-VAD, and caspase-3 inhibitor, z-DEVD, sensitized L929 cells to oridonin, however, a PARP inhibitor (DPQ) effectively blocked oridonin-induced cell death. After 12 h treatment, PARP proenzyme was significantly cleaved. This result indicated that oridonin-induced L929 cell death required PARP degradation in a caspase-independent manner. In addition, an MEK/ERK inhibitor (PD98059) markedly blocked oridonin-induced cell death, whereas a p38 inhibitor (SB203580) and JNK inhibitor (SP600125) weakly protected the cells against death. Treatment with 41.2 microM oridonin for 12 h induced significant and persistent ERK activation and p38 inactivation in L929 cells without evident changes in the protein levels. The responsiveness of ERK and p38 to oridonin suggests the involvement of these kinases in this apoptotic process. Moreover, oridonin increased the ratio of Bax/Bcl-2 protein expression, whereas it had no effect on the expression of Bcl-xL. These results indicate that regulation of the Bcl-2 and MAPK families maybe the effector mechanisms of oridonin-induced L929 cell death, independent of the caspase pathway. (+info)
Oridonin, a diterpenoid purified from Rabdosia rubescens, inhibits the proliferation of cells from lymphoid malignancies in association with blockade of the NF-kappa B signal pathways.
(3/8)
This study found that oridonin, a natural diterpenoid purified from Rabdosia rubescens, inhibited growth of multiple myeloma (MM; U266, RPMI8226), acute lymphoblastic T-cell leukemia (Jurkat), and adult T-cell leukemia (MT-1) cells with an effective dose that inhibited 50% of target cells (ED50) ranging from 0.75 to 2.7 microg/mL. Terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling staining showed that oridonin caused apoptosis of MT-1 cells in a time-dependent manner. We explored effects of oridonin on antiapoptotic Bcl-2 family members and found that it down-regulated levels of Mcl-1 and BCL-x(L), but not Bcl-2 protein, in both MT-1 and RPMI8226 cells. Further studies found that oridonin inhibited nuclear factor-kappa B (NF-kappa B) DNA-binding activity in these cells as measured by luciferase reporter gene, ELISA-based, and electrophoretic mobility shift assays. Oridonin also blocked tumor necrosis factor-alpha- and lipopolysaccharide-stimulated NF-kappa B activity in Jurkat cells as well as RAW264.7 murine macrophages. Of note, oridonin decreased survival of freshly isolated adult T-cell leukemia (three samples), acute lymphoblastic leukemia (one sample), chronic lymphocytic leukemia (one sample), non-Hodgkin's lymphoma (three samples), and MM (four samples) cells from patients in association with inhibition of NF-kappa B DNA-binding activity. On the other hand, oridonin did not affect survival of normal lymphoid cells from healthy volunteers. Taken together, oridonin might be useful as adjunctive therapy for individuals with lymphoid malignancies, including the lethal disease adult T-cell leukemia. (+info)
Pharmacokinetic behaviors and oral bioavailability of oridonin in rat plasma.
(4/8)
AIM: To study the intravenous and oral pharmacokinetic behavior of oridonin and its extent of absolute oral bioavailability in rats. METHODS: Oridonin was administered to rats via iv (5, 10 and 15 mg/kg), po (20, 40 and 80 mg/kg) or ip administration (10 mg/kg). The concentrations of oridonin in rat plasma were determined by a high performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC/ESI-MS) method and the pharmacokinetic parameters were determined by non-compartmental analysis. RESULTS: The plasma concentration of oridonin after intravenous administration decreased polyexponentially, and the pharmacokinetic parameters of oridonin were dose-independent within the examined range. Oridonin was absorbed rapidly after oral gavage with a t(max) of less than 15 min; the extent of absolute bioavailability of oridonin following oral administration was 4.32%, 4.58% and 10.8%. The extent of absolute bioavailability of oridonin following intraperitoneal administration was 12.6%. CONCLUSION: First order rate pharmacokinetics were observed for oridonin within the range of iv doses, while the extent of absolute oral bioavailability was rather low and dose- dependent. The low and dose-dependent extent of oral bioavailability may be due to the saturation of first-pass effects. (+info)
Oridonin induced autophagy in human cervical carcinoma HeLa cells through Ras, JNK, and P38 regulation.
(5/8)
In this study, we investigated autophagy induced by oridonin in HeLa cells. HeLa cells were exposed to oridonin, and the fluorescent changes, autophagic levels, and protein expressions were evaluated. Oridonin induced autophagy in HeLa cells in vitro in a dose- and time-dependent manner. Oridonin-treated HeLa cells, which had been prelabeled with the autophagosome-specific dye monodansylcadervarine (MDC), recruited more MDC-positive particles and had a significantly higher fluorescent density; and simultaneously, expressions of autophagy-related proteins, MAP-LC3 and Beclin 1, were increased by oridonin. In oridonin-induced Hela cells, pretreatment with 3-methyladenine (3-MA, the specific inhibitor of autophagy) dose-dependently decreased the autophagic ratio accompanied with downregulation of the protein expressions of MAP-LC3 and Beclin 1. Furthermore, when a Ras inhibitor was applied, the autophagic levels were augmented, whereas P38 and JNK inhibitors decreased the autophagic ratio significantly, indicating that this oridonin-induced autophagic process was negatively regulated by Ras, but positively regulated by P38 and JNK MAPKs. Raf-1 and ERK1/2 had no obvious correlation to these signaling pathways. (+info)
Reactive oxygen species mediate oridonin-induced HepG2 apoptosis through p53, MAPK, and mitochondrial signaling pathways.
(6/8)
Oridonin, a diterpenoid isolated from Rabdosia rubescences, could induce apoptosis through the generation of reactive oxygen species (ROS) in human hepatoma HepG2 cells. p53, a specific inhibitor of pifithrin alpha (PFT alpha), markedly inhibited ROS generation and apoptosis, showing that p53 was responsible for the cytotoxity of oridonin through mediation by ROS. Moreover, the ROS activated the p38 kinase, which in turn promoted the activation of p53, as verified by evidence showing that the ROS scavenger N-acetyl-cysteine (NAC) not only blocked the phosphorylation of p38 but also partially inhibited the activation of p53, and the p38 inhibitor SB203580 reduced the activation of p53 as well. Mitochondria were either the sources or the targets of ROS. This study showed that oridonin stimulated mitochondrial transmembrane permeabilization in a ROS-dependent manner because NAC almost thoroughly reversed the drop of mitochondrial transmembrane potential (Deltapsim) and the release of cytochrome c from the mitochondrial inter-membrane space into cytosol. Furthermore, as a result of mitochondrial permeability transition, procaspases-9 and -3 were cleaved into 37- and 17-kDa proteolytic products, respectively, which acted as executors of oridonin-induced apoptosis. (+info)
Hydroxyl radical (.OH) played a pivotal role in oridonin-induced apoptosis and autophagy in human epidermoid carcinoma A431 cells.
(7/8)
Oridonin, a diterpenoid compound extracted and purified from Rabdosia rubescen, has been reported to induce tumor cell apoptosis through tyrosine kinase pathway. To further examine the mechanism of oridonin, we selected human epidermoid carcinoma A431 cell as a test object. Besides apoptosis, oridonin also induced A431 cell autophagy, and this autophagy antagonized apoptosis and played a protective role for A431 cells. Reactive oxygen species (ROS) played a pivotal role in induction of cytotoxicity. Therefore, a ROS scavenger, N-acetylcysteine (NAC) combined with oridonin was appiled. Results of morphologic observation, flow cytometric analysis and Western blot analysis showed that NAC could significantly reverse both ROS generation and down-regulation of mitochondrial membrane potential in oridonin treated cells. NAC inhibited oridonin induced apoptosis through both the intrinsic and extrinsic apoptotic pathways. NAC effectively inhibited both oridonin-induced apoptosis and autophagy by reducing intracellular oxidative stress. To further examine the mechanism of ROS, exogenous enzyme antioxidants (superoxide dismutase (SOD), catalase (CAT)) and non-enzyme antioxidants (glutathione (GSH)) were applied to detect the effect of oridonin on ROS generation. Only GSH exerted a similar role with NAC, suggesting that hydroxyl radical (.OH) played the major role in oridonin-induced cell death. Oridonin could decrease the GSH level in A431 cells in a dose-dependent manner. In addition, after treatment with .OH donor, Fenton reagent, the changes in A431cells were similar to the results of oridonin treatment. All the results proved that .OH played the pivotal role in oridonin induced apoptosis and autophagy in A431 cells. (+info)
Oridonin induces apoptosis in gastric cancer through Apaf-1, cytochrome c and caspase-3 signaling pathway.
(8/8)