Apoptosis signaling triggered by the marine alkaloid ascididemin is routed via caspase-2 and JNK to mitochondria

Dirsch, Verena M.; Kirschke, Stephanie Olivia; Estermeier, Michael; Steffan, Bert; Vollmar, Angelika M.

doi:10.1038/sj.onc.1207281

Cited by 41 publications

(42 citation statements)

References 38 publications

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“…Numerous reports in the literature point to DNA damage as a trigger for apoptosis (Norbury and Zhivotovsky, 2004), which would be consistent with the results of this study. Caspase-2 has been suggested as a signal linking drug-induced DNA damage and mitochondrial dysfunction leading to downstream apoptotic events including caspase-3 activation (Lassus et al, 2002;Dirsch et al, 2004;Robertson et al, 2004). Our data demonstrate that RH1 treatment induced caspase-3 cleavage in NQ16 cells, suggesting a caspase-3-dependent route of RH1-induced apoptosis.…”

Section: In Vitro Toxicity Of Rh1 775supporting

confidence: 54%

RH1 Induces Cellular Damage in an NAD(P)H:Quinone Oxidoreductase 1-Dependent Manner: Relationship between DNA Cross-linking, Cell Cycle Perturbations, and Apoptosis

Dehn

Inayat-Hussain

Ross

2005

J Pharmacol Exp Ther

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Structure-based development of NAD(P)H:quinone oxidoreductase (NQO1)-directed antitumor quinones resulted in development of RH1 [2,5-diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone], a methyl-substituted diaziridinyl quinone. We conducted experiments to evaluate the mechanism of RH1-induced cytotoxicity and the inter-relationship between DNA cross-linking, cell cycle changes, and apoptosis using an isogenic cell line pair developed from the human breast cancer cell line MDA-MB-468 differing only in expression of wtNQO1 (NQ16 cells). Statistically significant DNA cross-linking was detected using a modified comet assay in cells with wtNQO1 within 1 h of dosing, whereas in parental cells, only marginal DNA cross-linking was observed and required a concentration up to 50 times higher. Cross-linking in NQ16 cells could be abrogated with 5-methoxy-1,2-dimethyl-3-[(4-nitrophenoxy)methyl]indole-4,7-dione, a mechanismbased inhibitor of NQO1. RH1 prolonged S phase and caused a G 2 /M block. Cell cycle changes were observed up to 10-fold lower in RH1 concentrations in NQ16 cells relative to parental cells. Apoptosis was similarly observed morphologically in both cell lines after RH1 treatment but was induced preferentially in NQ16 cells at lower concentrations and earlier time points. Marked cleavage of caspase-3 was observed in NQ16 cells relative to parental cells using lower concentrations of RH1. Temporally, low doses of RH1-induced rapid DNA cross-linking in NQ16 cells followed by induction of apoptosis at times when a G 2 /M block was not observed. This suggests that cell cycle arrest is not required for RH1-induced apoptosis and that DNA damage may directly initiate apoptotic events. In summary, RH1-induced preferential DNA cross-linking, cell cycle changes, and apoptosis in an NQO1-dependent manner.The bioactivation of antitumor quinones by the two-electron reductase NQO1 has attracted considerable interest after it was found that NQO1 was expressed at high levels throughout many human solid tumors (Cresteil and Jaiswal, 1991;Malkinson et al., 1992;Mikami et al., 1998). The structure-based development of NQO1-directed antitumor quinones led to the identification and testing of a number of compounds, including the aziridinylbenzoquinone RH1 [2,5-diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone], which is currently in clinical trials in the UK. Upon twoelectron reduction of the quinone by NQO1, the two aziridinyl functional groups undergo facile protonation, leading to aziridine ring opening. The resulting bifunctional alkylating species can covalently bind to DNA (forming inter-and intrastrand cross-links) and other cellular nucleophiles (Hargreaves et al., 1999). It is presumed that the cytotoxicity of RH1 is related to its ability to cross-link DNA (Ward et al., 2000) after activation by NQO1 because it does not appreciably redox cycle , nor does one-electron reduction appear to contribute significantly to the cytotoxicity of RH1. Kim et al. (2004b) did not find a difference in RH1 toxicit...

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Section: In Vitro Toxicity Of Rh1 775supporting

confidence: 54%

RH1 Induces Cellular Damage in an NAD(P)H:Quinone Oxidoreductase 1-Dependent Manner: Relationship between DNA Cross-linking, Cell Cycle Perturbations, and Apoptosis

Dehn

Inayat-Hussain

Ross

2005

J Pharmacol Exp Ther

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“…A recent report (39) showed that both caspase-2 and caspase-8 are activated in HOXA5-induced apoptosis of breast cancer cells, yet the sequential activation of these two caspases was not demonstrated. Another study showed that the marine alkaloid ascididemin induces Jurkat T cell apoptosis that requires caspase-2 activation upstream of mitochondria and caspase-8 activation as an effector caspase downstream of mitochondria (40). The present study is, to our knowledge, the first to show that caspase-2 may act upstream of caspase-8 before mitochondrial damage.…”

Section: Resultsmentioning

confidence: 56%

Sequential Caspase-2 and Caspase-8 Activation Upstream of Mitochondria during Ceramideand Etoposide-induced Apoptosis

Lin¹,

Chen

Chang³

et al. 2004

Journal of Biological Chemistry

121

113

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Recently, caspase-2 was shown to act upstream of mitochondria in stress-induced apoptosis. Activation of caspase-8, a key event in death receptor-mediated apoptosis, also has been demonstrated in death receptor-independent apoptosis. The regulation of these initiator caspases, which trigger the mitochondrial apoptotic pathway, is unclear. Here we report a potential regulatory role of caspase-2 on caspase-8 during ceramide-induced apoptosis. Our results demonstrate the sequential events of initiator caspase-2 and caspase-8 activation, Bid cleavage and translocation, and mitochondrial damage followed by downstream caspase-9 and -3 activation and cell apoptosis after ceramide induction in T cell lines. The expression of truncated Bid (tBid) and the reduction in mitochondrial transmembrane potential were blocked by caspase-2 or caspase-8, but not caspase-3, knockdown using an RNA interference technique. Ceramide-induced caspase-8 activation, mitochondrial damage, and apoptosis were blocked in caspase-2 short interfering RNA-expressing cells. Therefore, caspase-2 acts upstream of caspase-8 during ceramide-induced mitochondrial apoptosis. Similarly, sequential caspase-2 and caspase-8 activation upstream of mitochondria was also observed in etoposide-induced apoptosis. These data suggest sequential initiator caspase-2 and caspase-8 activation in the mitochondrial apoptotic pathway induced by ceramide or etoposide.A mitochondrial apoptotic pathway is required for various death stimuli (1, 2). The involvement of initiator caspases before mitochondrial damage has been shown (3, 4). Caspase-8 activation followed by the cleavage of the Bcl-2 family protein Bid, a BH3 domain-containing proapoptotic protein, induces mitochondrial damage during death receptor-mediated apoptosis (5-8). Activation of caspase-8 also has been demonstrated in death receptor-independent apoptosis (9, 10). Caspase-2 recently was shown to act upstream of mitochondria to promote cytochrome c release and apoptosis (11)(12)(13)(14). The regulation of these initiator caspases leading to the mitochondria-mediated apoptotic pathway remains unresolved.Ceramide, a product of sphingolipid metabolism, regulates diverse cellular responses, including proliferation, differentiation, and apoptosis. Although the role of ceramide as a signaling molecule remains debatable (15, 16), some early work suggested that various extracellular agents and stress stimuli, such as tumor necrosis factor-␣ (TNF␣), Fas, chemotherapeutic agents, irradiation, and heat, might cause accumulation of ceramide. Ceramide modulates the biochemical and cellular processes that lead to apoptosis (17-21). The mechanisms by which ceramide regulates apoptotic events have not been fully defined. Ceramide activates a number of enzymes involved in stress-signaling pathways, including both protein kinases and protein phosphatases. A recent study indicates that ceramide-induced neuronal apoptosis is associated with dephosphorylation of Akt, Bcl2-associated death promoter (BAD), forkhead transcriptional ...

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“…Notably, while both CTAR1 and CTAR2 are known to activate the NF B axis, CTAR2 alone engages the c-Jun N-terminal kinase (JNK) pathway. 36 Of considerable interest, a recent publication 39 that appeared during the writing of this article has provided evidence that apoptosis signaling triggered by the marine alkaloid, ascididemin (ASC), is dependent on JNK activation upstream of caspase-2; caspase-2, in turn, was shown to link the DNA-damaging activity of ASC to downstream mitochondrial perturbation. Moreover, Debatin et al have shown that inhibition of JNK activity delays the onset of apoptosis induced by cellular stress (including cisplatin and doxorubicin) in a Jurkat T cell model.…”

Section: Discussionmentioning

confidence: 99%

Epstein‐Barr virus‐encoded latent membrane protein 1 promotes stress‐induced apoptosis upstream of caspase‐2‐dependent mitochondrial perturbation

Zhang

Uthaisang

et al. 2004

Intl Journal of Cancer

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Previous studies have shown that Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) enhances etoposideinduced apoptosis in epithelial cells. Our study was undertaken to further dissect the modulation of tumor cell apoptosis by this viral protein. Using an inducible system of LMP1 expression in HeLa cells, we show herein that etoposide-triggered apoptosis, as evidenced by nuclear condensation and caspase-3 activation, is enhanced by LMP1. LMP1 also potentiates etoposide-induced processing and activation of caspase-2 in this model and enhances the dissipation of mitochondrial transmembrane potential and the release of cytochrome c in response to etoposide. Moreover, cisplatin-triggered activation of caspases 2 and 3 is potentiated upon expression of LMP1. A similar LMP1-mediated enhancement of cisplatin-induced caspase activation was seen upon stable transfection of wild-type LMP1 into the nasopharyngeal carcinoma cell line, TW03. Finally, using deletion mutants of LMP1 to determine the region of LMP1 required for apoptosis potentiation, we found that amino acids 350 -386 (located within the CTAR2 domain) were responsible for sensitizing cells to cisplatin. We conclude that LMP1-dependent potentiation of stress-induced apoptosis occurs at an early step in the apoptosis cascade, upstream of the activation of caspase-2, and involves the C-terminal signaling domain of LMP1. These findings could have important ramifications for the treatment of EBV-associated malignancies of epithelial origin, including nasopharyngeal carcinoma.

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Apoptosis signaling triggered by the marine alkaloid ascididemin is routed via caspase-2 and JNK to mitochondria

Cited by 41 publications

References 38 publications

RH1 Induces Cellular Damage in an NAD(P)H:Quinone Oxidoreductase 1-Dependent Manner: Relationship between DNA Cross-linking, Cell Cycle Perturbations, and Apoptosis

RH1 Induces Cellular Damage in an NAD(P)H:Quinone Oxidoreductase 1-Dependent Manner: Relationship between DNA Cross-linking, Cell Cycle Perturbations, and Apoptosis

Sequential Caspase-2 and Caspase-8 Activation Upstream of Mitochondria during Ceramideand Etoposide-induced Apoptosis

Epstein‐Barr virus‐encoded latent membrane protein 1 promotes stress‐induced apoptosis upstream of caspase‐2‐dependent mitochondrial perturbation

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