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Takashi Ikejima - One of the best experts on this subject based on the ideXlab platform.

  • inhibition of egfr signaling augments Oridonin induced apoptosis in human laryngeal cancer cells via enhancing oxidative stress coincident with activation of both the intrinsic and extrinsic apoptotic pathways
    Cancer Letters, 2010
    Co-Authors: Ning Kang, Shin-ichi Tashiro, Satoshi Onodera, Feng Qiu, Jinghai Zhang, Takashi Ikejima
    Abstract:

    Oridonin, a bioactive diterpenoid isolated from Rabdosia rubescens, has been reported to have anti-tumor effects, while the epidermal growth factor receptor (EGFR) signal pathway has been reported to play a vital role in the biological progression of several tumors and to be a target for therapeutic intervention. In this work, we show that inhibition of EGFR with tyrphostin AG1478 enhances Oridonin-induced cell death in human laryngeal cancer cells HEp-2, a cell line characterized by EGFR gene amplification. The enhanced apoptotic effect correlates with high expression and activation of Bax, FADD, caspase-8 as well as caspase-3 and decreased protein levels of Bcl(2) and SIRT1, suggesting that both the extrinsic and intrinsic apoptosis pathways are involved in the apoptotic processes. However, treatment with Oridonin and AG1478 greatly enhances nuclear translocation of apoptosis inducing factor (AIF) without caspase-9 activation, indicating that the apoptosis occurs via a caspase-9-independent mitochondrial pathway. Here, it is the active form of caspase-8 but not caspase-9 that activates downstream effector caspase-3, resulting in the cleavage of critical cellular proteins and apoptosis. Furthermore, the combined use of AG1478 and Oridonin augments the production of reactive oxygen species (ROS). Incubation of cells with N-Acetylcysteine (NAC) attenuates the apoptosis and the mitochondrial membrane potential (Deltapsim) disruption induced by the combination of Oridonin and AG1478, which indicates that ROS plays a pivotal role in cell death. In conclusion, targeting EGFR combined with other conventional pro-apoptotic drugs should be a potentially very effective anti-neoplastic therapy for laryngeal cancer.

  • Oridonin induces g2 m arrest and apoptosis via activating erk p53 apoptotic pathway and inhibiting ptk ras raf jnk survival pathway in murine fibrosarcoma l929 cells
    Archives of Biochemistry and Biophysics, 2009
    Co-Authors: Yan Cheng, Shin-ichi Tashiro, Satoshi Onodera, Feng Qiu, Takashi Ikejima
    Abstract:

    Oridonin was reported to induce L929 cell apoptosis via ROS-mediated mitochondrial and ERK pathways; however, the precise mechanisms by which Oridonin induces cell death remain unclear. Herein, we found that Oridonin treatment induced an increase in G(2)/M phase cell percentage. And, G(2)/M phase arrest was associated with down-regulation of cell cycle related cdc2, cdc25c and cyclinB levels, as well as up-regulation of p21 and p-cdc2 levels. In addition, we discovered that interruption of p53 activation decreased Oridonin-induced apoptosis, and blocking ERK by specific inhibitors or siRNA suppressed Oridonin-induced p53 activation. Moreover, inhibition of PTK, protein kinase C, Ras, Raf or JNK activation increased Oridonin-induced apoptosis. Also, the level of Ras, Raf or JNK was down-regulated by Oridonin, and the inhibition of PTK, Ras, Raf activation decreased p-JNK level. In conclusion, Oridonin induces L929 cell G(2)/M arrest and apoptosis, which is regulated by promoting ERK-p53 apoptotic pathway and suppressing PTK-mediated survival pathway.

  • nf κb facilitates Oridonin induced apoptosis and autophagy in ht1080 cells through a p53 mediated pathway
    Archives of Biochemistry and Biophysics, 2009
    Co-Authors: Yahong Zhang, Yingliang Wu, Shin-ichi Tashiro, Satoshi Onodera, Takashi Ikejima
    Abstract:

    Abstract In this study, we investigated the molecular mechanisms involving in Oridonin-induced apoptosis and autophagy. We found that apoptosis and autophagy were simultaneously induced by Oridonin time-dependently in HT1080 cells, and inhibition of autophagy by 3MA decreased Oridonin-induced apoptosis, indicating that they act in synergy to mediate cell death. In addition, treatment with Oridonin caused an increase in NF-κB and p53 activities in a time-dependent manner. Inhibition of NF-κB or p53 activation by its specific inhibitor PDTC or pifithrin-α respectively, significantly reduced both Oridonin-induced apoptosis and autophagy accompanied by the decrease in Beclin 1 and LC3 levels. Further experiments confirmed that Oridonin-induced p53 activation was reduced by the NF-κB inhibitor whereas the activation of NF-κB was not affected by p53 inhibition. Taken together, these results demonstrate that NF-κB promotes Oridonin-induced apoptotic and autophagic cell death through regulating p53 activation in HT1080 cells.

  • molecular mechanisms of Oridonin induced apoptosis and autophagy in murine fibrosarcoma l929 cells
    Autophagy, 2009
    Co-Authors: Yan Cheng, Feng Qiu, Takashi Ikejima
    Abstract:

    Apoptosis and autophagy are genetically regulated, evolutionarily conserved processes that can jointly seal the fate of cancer cells. However, substantial gaps remain in our understanding of the molecular mechanisms that mediate the two cellular processes. In the present study, the exposure of murine fibrosarcoma L929 cells to Oridonin led to the generation of intracellular reactive oxygen species (ROS) and, subsequently, the ROS triggered apoptosis by Bax translocation, cytochrome c release and ERK activations. In addition, Oridonin induced autophagy in L929 cells, and the inhibition of autophagy by 3-MA or siRNA against LC3 and beclin 1 promoted Oridonin-induced apoptosis. Furthermore, p38 and NFkappaB were confirmed to have roles in inhibiting apoptosis but promoting autophagy. Moreover, the inhibition of autophagy could reduce Oridonin-induced activation of p38. Finally, NFkappaB activation was inhibited by blocking the p38 pathway. In conclusion, these findings indicate that Oridonin-induced apoptosis can be regulated by ROS-mediated signaling pathways, and Oridonin-induced autophagy may block apoptosis by upregulating p38 and NFkappaB activation.

  • autophagy inhibits reactive oxygen species mediated apoptosis via activating p38 nuclear factor kappa b survival pathways in Oridonin treated murine fibrosarcoma l929 cells
    FEBS Journal, 2009
    Co-Authors: Yan Cheng, Shin-ichi Tashiro, Satoshi Onodera, Feng Qiu, Zhaoming Guo, Takashi Ikejima
    Abstract:

    Autophagy and apoptosis have been known to be interconnected positively or negatively; however, the molecular mechanisms mediating these two cellular processes are not fully understood. In the present study, we demonstrated that the exposure of L929 cells to Oridonin led to intracellular reactive oxygen species generation, followed by lipid peroxidation, as well as decreases in superoxide dismutase and glutathione activities. The reactive oxygen species scavenger N-acetyl-cysteine resulted in the complete inhibition of Oridonin-induced apoptosis and mitochondrial membrane potential collapse. We showed that reactive oxygen species triggered apoptosis by Bax translocation, cytochrome c release and extracellular signal-regulated kinase activation. Further data confirmed that Oridonin also induced L929 cell autophagy, as demonstrated by extensive autophagic vacuolization and the punctuate distribution of monodansylcadaverine staining and GFP-LC3, as well as the LC3-II/LC3-I proportion and Beclin 1 activation. Subsequently, we found that inhibition of autophagy by 3-methyladenine or small interfering RNA against LC3 and Beclin 1 promoted Oridonin-induced cell apoptosis. The effects of p38 and nuclear factor-kappa B in Oridonin-induced apoptosis and autophagy were further examined. Interruption of p38 and nuclear factor-kappa B activation by specific inhibitors or small interfering RNAs promoted apoptosis and reactive oxygen species generation, but decreased autophagy. Moreover, we showed that inhibition of autophagy reduced Oridonin-induced activation of p38. Additionally, nuclear factor-kappa B activation was inhibited by blocking the p38 pathway. Consequently, these findings indicate that Oridonin-induced L929 cell apoptosis is regulated by reactive oxygen species-mediated signaling pathways, and that Oridonin-induced autophagy may block apoptosis by up-regulating p38 and nuclear factor-kappa B activation.

Shin-ichi Tashiro - One of the best experts on this subject based on the ideXlab platform.

  • inhibition of egfr signaling augments Oridonin induced apoptosis in human laryngeal cancer cells via enhancing oxidative stress coincident with activation of both the intrinsic and extrinsic apoptotic pathways
    Cancer Letters, 2010
    Co-Authors: Ning Kang, Shin-ichi Tashiro, Satoshi Onodera, Feng Qiu, Jinghai Zhang, Takashi Ikejima
    Abstract:

    Oridonin, a bioactive diterpenoid isolated from Rabdosia rubescens, has been reported to have anti-tumor effects, while the epidermal growth factor receptor (EGFR) signal pathway has been reported to play a vital role in the biological progression of several tumors and to be a target for therapeutic intervention. In this work, we show that inhibition of EGFR with tyrphostin AG1478 enhances Oridonin-induced cell death in human laryngeal cancer cells HEp-2, a cell line characterized by EGFR gene amplification. The enhanced apoptotic effect correlates with high expression and activation of Bax, FADD, caspase-8 as well as caspase-3 and decreased protein levels of Bcl(2) and SIRT1, suggesting that both the extrinsic and intrinsic apoptosis pathways are involved in the apoptotic processes. However, treatment with Oridonin and AG1478 greatly enhances nuclear translocation of apoptosis inducing factor (AIF) without caspase-9 activation, indicating that the apoptosis occurs via a caspase-9-independent mitochondrial pathway. Here, it is the active form of caspase-8 but not caspase-9 that activates downstream effector caspase-3, resulting in the cleavage of critical cellular proteins and apoptosis. Furthermore, the combined use of AG1478 and Oridonin augments the production of reactive oxygen species (ROS). Incubation of cells with N-Acetylcysteine (NAC) attenuates the apoptosis and the mitochondrial membrane potential (Deltapsim) disruption induced by the combination of Oridonin and AG1478, which indicates that ROS plays a pivotal role in cell death. In conclusion, targeting EGFR combined with other conventional pro-apoptotic drugs should be a potentially very effective anti-neoplastic therapy for laryngeal cancer.

  • Oridonin induces g2 m arrest and apoptosis via activating erk p53 apoptotic pathway and inhibiting ptk ras raf jnk survival pathway in murine fibrosarcoma l929 cells
    Archives of Biochemistry and Biophysics, 2009
    Co-Authors: Yan Cheng, Shin-ichi Tashiro, Satoshi Onodera, Feng Qiu, Takashi Ikejima
    Abstract:

    Oridonin was reported to induce L929 cell apoptosis via ROS-mediated mitochondrial and ERK pathways; however, the precise mechanisms by which Oridonin induces cell death remain unclear. Herein, we found that Oridonin treatment induced an increase in G(2)/M phase cell percentage. And, G(2)/M phase arrest was associated with down-regulation of cell cycle related cdc2, cdc25c and cyclinB levels, as well as up-regulation of p21 and p-cdc2 levels. In addition, we discovered that interruption of p53 activation decreased Oridonin-induced apoptosis, and blocking ERK by specific inhibitors or siRNA suppressed Oridonin-induced p53 activation. Moreover, inhibition of PTK, protein kinase C, Ras, Raf or JNK activation increased Oridonin-induced apoptosis. Also, the level of Ras, Raf or JNK was down-regulated by Oridonin, and the inhibition of PTK, Ras, Raf activation decreased p-JNK level. In conclusion, Oridonin induces L929 cell G(2)/M arrest and apoptosis, which is regulated by promoting ERK-p53 apoptotic pathway and suppressing PTK-mediated survival pathway.

  • nf κb facilitates Oridonin induced apoptosis and autophagy in ht1080 cells through a p53 mediated pathway
    Archives of Biochemistry and Biophysics, 2009
    Co-Authors: Yahong Zhang, Yingliang Wu, Shin-ichi Tashiro, Satoshi Onodera, Takashi Ikejima
    Abstract:

    Abstract In this study, we investigated the molecular mechanisms involving in Oridonin-induced apoptosis and autophagy. We found that apoptosis and autophagy were simultaneously induced by Oridonin time-dependently in HT1080 cells, and inhibition of autophagy by 3MA decreased Oridonin-induced apoptosis, indicating that they act in synergy to mediate cell death. In addition, treatment with Oridonin caused an increase in NF-κB and p53 activities in a time-dependent manner. Inhibition of NF-κB or p53 activation by its specific inhibitor PDTC or pifithrin-α respectively, significantly reduced both Oridonin-induced apoptosis and autophagy accompanied by the decrease in Beclin 1 and LC3 levels. Further experiments confirmed that Oridonin-induced p53 activation was reduced by the NF-κB inhibitor whereas the activation of NF-κB was not affected by p53 inhibition. Taken together, these results demonstrate that NF-κB promotes Oridonin-induced apoptotic and autophagic cell death through regulating p53 activation in HT1080 cells.

  • autophagy inhibits reactive oxygen species mediated apoptosis via activating p38 nuclear factor kappa b survival pathways in Oridonin treated murine fibrosarcoma l929 cells
    FEBS Journal, 2009
    Co-Authors: Yan Cheng, Shin-ichi Tashiro, Satoshi Onodera, Feng Qiu, Zhaoming Guo, Takashi Ikejima
    Abstract:

    Autophagy and apoptosis have been known to be interconnected positively or negatively; however, the molecular mechanisms mediating these two cellular processes are not fully understood. In the present study, we demonstrated that the exposure of L929 cells to Oridonin led to intracellular reactive oxygen species generation, followed by lipid peroxidation, as well as decreases in superoxide dismutase and glutathione activities. The reactive oxygen species scavenger N-acetyl-cysteine resulted in the complete inhibition of Oridonin-induced apoptosis and mitochondrial membrane potential collapse. We showed that reactive oxygen species triggered apoptosis by Bax translocation, cytochrome c release and extracellular signal-regulated kinase activation. Further data confirmed that Oridonin also induced L929 cell autophagy, as demonstrated by extensive autophagic vacuolization and the punctuate distribution of monodansylcadaverine staining and GFP-LC3, as well as the LC3-II/LC3-I proportion and Beclin 1 activation. Subsequently, we found that inhibition of autophagy by 3-methyladenine or small interfering RNA against LC3 and Beclin 1 promoted Oridonin-induced cell apoptosis. The effects of p38 and nuclear factor-kappa B in Oridonin-induced apoptosis and autophagy were further examined. Interruption of p38 and nuclear factor-kappa B activation by specific inhibitors or small interfering RNAs promoted apoptosis and reactive oxygen species generation, but decreased autophagy. Moreover, we showed that inhibition of autophagy reduced Oridonin-induced activation of p38. Additionally, nuclear factor-kappa B activation was inhibited by blocking the p38 pathway. Consequently, these findings indicate that Oridonin-induced L929 cell apoptosis is regulated by reactive oxygen species-mediated signaling pathways, and that Oridonin-induced autophagy may block apoptosis by up-regulating p38 and nuclear factor-kappa B activation.

  • caspase inhibition augmented Oridonin induced cell death in murine fibrosarcoma l929 by enhancing reactive oxygen species generation
    Journal of Pharmacological Sciences, 2008
    Co-Authors: Jian Huang, Shin-ichi Tashiro, Satoshi Onodera, Jia Yang, Takashi Ikejima
    Abstract:

    Oridonin, a diterpenoid isolated from Rabdosia rubescences, has been reported to have antitumor effects. In this study, the growth-inhibitory activity of Oridonin for L929 cells was exerted in a time-and dose-dependent manner. After treatment with Oridonin for 24 h, L929 cells underwent both apoptosis and necrosis as measured by an lactate dehydrogenase (LDH) activity-based assay. A rapid generation of reactive oxygen species (ROS) was triggered by Oridonin, and subsequently up-regulation of phospho-p53 (ser 15) expression and an increased expression ratio of Bax/Bcl-2 was observed. Furthermore, there was a significant fall in mitochondrial membrane potential (MMP) and increase in caspase-3 activity after exposure to Oridonin for 24 h. Surprisingly, the pan-caspase inhibitor z-VAD-fmk and caspase3 inhibitor z-DEVD-fmk rendered L929 cells more sensitive to Oridonin, rather than preventing Oridonin-induced cell death. Oridonin and z-VAD-fmk co-treatment not only resulted in an even higher ROS production, but also made a more significant reduction in the MMP. Pretreatment of ROS scavenger N-acetylcysteine (NAC) led to a complete inhibition of Oridonin-induced cell death, intracellular ROS generation, and MMP collapse. NAC treatment also reversed the potentiation of cell death by the pan-caspase inhibitor z-VAD-fmk. Taken together, these observations showed that Oridonin-induced cell death in L929 cells involved intracellular ROS generation, activation of phospho-p53 (ser 15), and up-regulation of the Bax/Bcl-2 ratio; and the augmented cell death by z-VAD-fmk was dependent on an increased ROS production.

Satoshi Onodera - One of the best experts on this subject based on the ideXlab platform.

  • inhibition of egfr signaling augments Oridonin induced apoptosis in human laryngeal cancer cells via enhancing oxidative stress coincident with activation of both the intrinsic and extrinsic apoptotic pathways
    Cancer Letters, 2010
    Co-Authors: Ning Kang, Shin-ichi Tashiro, Satoshi Onodera, Feng Qiu, Jinghai Zhang, Takashi Ikejima
    Abstract:

    Oridonin, a bioactive diterpenoid isolated from Rabdosia rubescens, has been reported to have anti-tumor effects, while the epidermal growth factor receptor (EGFR) signal pathway has been reported to play a vital role in the biological progression of several tumors and to be a target for therapeutic intervention. In this work, we show that inhibition of EGFR with tyrphostin AG1478 enhances Oridonin-induced cell death in human laryngeal cancer cells HEp-2, a cell line characterized by EGFR gene amplification. The enhanced apoptotic effect correlates with high expression and activation of Bax, FADD, caspase-8 as well as caspase-3 and decreased protein levels of Bcl(2) and SIRT1, suggesting that both the extrinsic and intrinsic apoptosis pathways are involved in the apoptotic processes. However, treatment with Oridonin and AG1478 greatly enhances nuclear translocation of apoptosis inducing factor (AIF) without caspase-9 activation, indicating that the apoptosis occurs via a caspase-9-independent mitochondrial pathway. Here, it is the active form of caspase-8 but not caspase-9 that activates downstream effector caspase-3, resulting in the cleavage of critical cellular proteins and apoptosis. Furthermore, the combined use of AG1478 and Oridonin augments the production of reactive oxygen species (ROS). Incubation of cells with N-Acetylcysteine (NAC) attenuates the apoptosis and the mitochondrial membrane potential (Deltapsim) disruption induced by the combination of Oridonin and AG1478, which indicates that ROS plays a pivotal role in cell death. In conclusion, targeting EGFR combined with other conventional pro-apoptotic drugs should be a potentially very effective anti-neoplastic therapy for laryngeal cancer.

  • Oridonin induces g2 m arrest and apoptosis via activating erk p53 apoptotic pathway and inhibiting ptk ras raf jnk survival pathway in murine fibrosarcoma l929 cells
    Archives of Biochemistry and Biophysics, 2009
    Co-Authors: Yan Cheng, Shin-ichi Tashiro, Satoshi Onodera, Feng Qiu, Takashi Ikejima
    Abstract:

    Oridonin was reported to induce L929 cell apoptosis via ROS-mediated mitochondrial and ERK pathways; however, the precise mechanisms by which Oridonin induces cell death remain unclear. Herein, we found that Oridonin treatment induced an increase in G(2)/M phase cell percentage. And, G(2)/M phase arrest was associated with down-regulation of cell cycle related cdc2, cdc25c and cyclinB levels, as well as up-regulation of p21 and p-cdc2 levels. In addition, we discovered that interruption of p53 activation decreased Oridonin-induced apoptosis, and blocking ERK by specific inhibitors or siRNA suppressed Oridonin-induced p53 activation. Moreover, inhibition of PTK, protein kinase C, Ras, Raf or JNK activation increased Oridonin-induced apoptosis. Also, the level of Ras, Raf or JNK was down-regulated by Oridonin, and the inhibition of PTK, Ras, Raf activation decreased p-JNK level. In conclusion, Oridonin induces L929 cell G(2)/M arrest and apoptosis, which is regulated by promoting ERK-p53 apoptotic pathway and suppressing PTK-mediated survival pathway.

  • nf κb facilitates Oridonin induced apoptosis and autophagy in ht1080 cells through a p53 mediated pathway
    Archives of Biochemistry and Biophysics, 2009
    Co-Authors: Yahong Zhang, Yingliang Wu, Shin-ichi Tashiro, Satoshi Onodera, Takashi Ikejima
    Abstract:

    Abstract In this study, we investigated the molecular mechanisms involving in Oridonin-induced apoptosis and autophagy. We found that apoptosis and autophagy were simultaneously induced by Oridonin time-dependently in HT1080 cells, and inhibition of autophagy by 3MA decreased Oridonin-induced apoptosis, indicating that they act in synergy to mediate cell death. In addition, treatment with Oridonin caused an increase in NF-κB and p53 activities in a time-dependent manner. Inhibition of NF-κB or p53 activation by its specific inhibitor PDTC or pifithrin-α respectively, significantly reduced both Oridonin-induced apoptosis and autophagy accompanied by the decrease in Beclin 1 and LC3 levels. Further experiments confirmed that Oridonin-induced p53 activation was reduced by the NF-κB inhibitor whereas the activation of NF-κB was not affected by p53 inhibition. Taken together, these results demonstrate that NF-κB promotes Oridonin-induced apoptotic and autophagic cell death through regulating p53 activation in HT1080 cells.

  • autophagy inhibits reactive oxygen species mediated apoptosis via activating p38 nuclear factor kappa b survival pathways in Oridonin treated murine fibrosarcoma l929 cells
    FEBS Journal, 2009
    Co-Authors: Yan Cheng, Shin-ichi Tashiro, Satoshi Onodera, Feng Qiu, Zhaoming Guo, Takashi Ikejima
    Abstract:

    Autophagy and apoptosis have been known to be interconnected positively or negatively; however, the molecular mechanisms mediating these two cellular processes are not fully understood. In the present study, we demonstrated that the exposure of L929 cells to Oridonin led to intracellular reactive oxygen species generation, followed by lipid peroxidation, as well as decreases in superoxide dismutase and glutathione activities. The reactive oxygen species scavenger N-acetyl-cysteine resulted in the complete inhibition of Oridonin-induced apoptosis and mitochondrial membrane potential collapse. We showed that reactive oxygen species triggered apoptosis by Bax translocation, cytochrome c release and extracellular signal-regulated kinase activation. Further data confirmed that Oridonin also induced L929 cell autophagy, as demonstrated by extensive autophagic vacuolization and the punctuate distribution of monodansylcadaverine staining and GFP-LC3, as well as the LC3-II/LC3-I proportion and Beclin 1 activation. Subsequently, we found that inhibition of autophagy by 3-methyladenine or small interfering RNA against LC3 and Beclin 1 promoted Oridonin-induced cell apoptosis. The effects of p38 and nuclear factor-kappa B in Oridonin-induced apoptosis and autophagy were further examined. Interruption of p38 and nuclear factor-kappa B activation by specific inhibitors or small interfering RNAs promoted apoptosis and reactive oxygen species generation, but decreased autophagy. Moreover, we showed that inhibition of autophagy reduced Oridonin-induced activation of p38. Additionally, nuclear factor-kappa B activation was inhibited by blocking the p38 pathway. Consequently, these findings indicate that Oridonin-induced L929 cell apoptosis is regulated by reactive oxygen species-mediated signaling pathways, and that Oridonin-induced autophagy may block apoptosis by up-regulating p38 and nuclear factor-kappa B activation.

  • caspase inhibition augmented Oridonin induced cell death in murine fibrosarcoma l929 by enhancing reactive oxygen species generation
    Journal of Pharmacological Sciences, 2008
    Co-Authors: Jian Huang, Shin-ichi Tashiro, Satoshi Onodera, Jia Yang, Takashi Ikejima
    Abstract:

    Oridonin, a diterpenoid isolated from Rabdosia rubescences, has been reported to have antitumor effects. In this study, the growth-inhibitory activity of Oridonin for L929 cells was exerted in a time-and dose-dependent manner. After treatment with Oridonin for 24 h, L929 cells underwent both apoptosis and necrosis as measured by an lactate dehydrogenase (LDH) activity-based assay. A rapid generation of reactive oxygen species (ROS) was triggered by Oridonin, and subsequently up-regulation of phospho-p53 (ser 15) expression and an increased expression ratio of Bax/Bcl-2 was observed. Furthermore, there was a significant fall in mitochondrial membrane potential (MMP) and increase in caspase-3 activity after exposure to Oridonin for 24 h. Surprisingly, the pan-caspase inhibitor z-VAD-fmk and caspase3 inhibitor z-DEVD-fmk rendered L929 cells more sensitive to Oridonin, rather than preventing Oridonin-induced cell death. Oridonin and z-VAD-fmk co-treatment not only resulted in an even higher ROS production, but also made a more significant reduction in the MMP. Pretreatment of ROS scavenger N-acetylcysteine (NAC) led to a complete inhibition of Oridonin-induced cell death, intracellular ROS generation, and MMP collapse. NAC treatment also reversed the potentiation of cell death by the pan-caspase inhibitor z-VAD-fmk. Taken together, these observations showed that Oridonin-induced cell death in L929 cells involved intracellular ROS generation, activation of phospho-p53 (ser 15), and up-regulation of the Bax/Bcl-2 ratio; and the augmented cell death by z-VAD-fmk was dependent on an increased ROS production.

Peihui Yang - One of the best experts on this subject based on the ideXlab platform.

Jinyi Xu - One of the best experts on this subject based on the ideXlab platform.