Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P42574 (caspase-3)
 45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many pro-apoptotic signals activate caspase-9, an initiator protease that activates caspase-3 and downstream caspases to initiate cellular destruction. However, survival signals can impinge on this pathway and suppress apoptosis. Activation of the Ras-Raf-MEK-ERK mitogen-activated protein kinase (MAPK) pathway is associated with protection of cells from apoptosis and inhibition of caspase-3 activation, although the targets are unknown. Here, we show that the ERK MAPK pathway inhibits caspase-9 activity by direct phosphorylation. In mammalian cell extracts, cytochrome c-induced activation of caspases-9 and -3 requires okadaic-acid-sensitive protein phosphatase activity. The opposing protein kinase activity is overcome by treatment with the broad-specificity kinase inhibitor staurosporine or with inhibitors of MEK1/2. Caspase-9 is phosphorylated at Thr 125, a conserved MAPK consensus site targeted by ERK2 in vitro, in a MEK-dependent manner in cells stimulated with epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol-13-acetate (TPA). Phosphorylation at Thr 125 is sufficient to block caspase-9 processing and subsequent caspase-3 activation. We suggest that phosphorylation and inhibition of caspase-9 by ERK promotes cell survival during development and tissue homeostasis. This mechanism may also contribute to tumorigenesis when the ERK MAPK pathway is constitutively activated.
 ...
PMID:Inhibition of caspase-9 through phosphorylation at Thr 125 by ERK MAPK. 1279 50

Many apoptotic pathways culminate in the activation of caspase cascades usually triggered by the apical caspases-8 or -9. We describe a paradigm where apoptosis is initiated by the effector caspase-3. Diethylmaleate (DEM)-induced apoptotic damage in Jurkat cells was blocked by the anti-apoptotic protein Bcl-2, whereas, a peptide inhibitor of caspase-3 but not caspase-9 blocked DEM-induced mitochondrial damage. Isogenic Jurkat cell lines deficient for caspase-8 or the adaptor FADD (Fas associated death domain) were not protected from DEM-induced apoptosis. Caspase-3 activation preceded that of caspase-9 and initial processing of caspase-3 was regulated independent of caspase-9 and Bcl-2. However, inhibitors of caspase-9 or caspase-6 regulated caspase-3 later in the pathway. We explored the mechanism by which caspase-3 processing is regulated in this system. DEM triggered a loss of Erk-1/2 phosphorylation and XIAP (X-linked inhibitor of apoptosis protein) expression. The phorbol ester PMA activated a MEK-dependent pathway to block caspase-3 processing and cell death. Constitutively active MEK-1 (CA-MEK) upregulated XIAP expression and exogenous XIAP inhibited DEM-induced apoptotic damage. Thus, we describe a pathway where caspase-3 functions to initiate apoptotic damage and caspase-9 and caspase-6 amplify the apoptotic cascade. Further, we show that MEK may regulate caspase-3 activation via the regulation of XIAP expression in these cells.
 ...
PMID:Caspase-3 activation is an early event and initiates apoptotic damage in a human leukemia cell line. 1281 79

H11, the eukaryotic homologue of a herpes simplex virus protein, has the crystallin motif of heat shock proteins (Hsp), but it differs from canonical family members in that mRNA and protein levels were reduced in various tumor tissues and cell lines (viz. melanoma, prostate cancer and sarcoma) relative to their normal counterparts. In these cells, expression was not restored by heat shock, but rather by the demethylating agent 5-aza-2'-deoxycytidine (Aza-C). Forced H11 expression by Aza-C treatment, transient transfection with H11 expression vectors, or retrovirus-mediated delivery of H11 under the control of a tetracycline-sensitive promoter triggered apoptosis. This is evidenced by a significant (p < 0.001) increase in the percentage of cells positive for terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) and for activation of caspase-3 and p38MAPK and by the co-localization of TUNEL+ nuclei with increased H11 levels. Apoptosis was partially inhibited by the pancaspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone or the p38MAPK inhibitor SB203580. It was abrogated by co-treatment with both inhibitors, suggesting that H11-triggered apoptosis is both caspase- and p38MAPK-dependent. A single site mutant (H11-W51C) had cytoprotective activity related to MEK/ERK activation, and it blocked H11-induced apoptosis in co-transfected and Aza-C-treated cells, indicating that it is a dominant negative mutant. This is the first report of a heat shock protein with proapoptotic activity.
 ...
PMID:Forced expression of the H11 heat shock protein can be regulated by DNA methylation and trigger apoptosis in human cells. 1283 17

The effects of Dox (Dox), paclitaxel (Taxol), and serum starvation on the regulation of XIAP (X-linked inhibitor of apoptosis), Bcl-2 phosphorylation, and apoptosis were evaluated in human H460 non-small cell lung cancer cells. Protein kinases that responded to these treatments as prosurvival elements in signal transduction were identified by simultaneously screening phosphorylation of protein kinases in H460 cells cultured in serum-free medium or treated with Dox. We demonstrated that Dox and Taxol induced apoptosis through down-regulation of XIAP and phosphorylation of Bcl-2 in a concentration-dependent manner without changing expression of Bcl-xL in H460 cells. These effects were paralleled by activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase protein. We identified that serum starvation and Dox reduced phosphorylation of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK), protein kinase C (PKC) alpha/beta and c-Jun NH(2)-terminal kinase. The MEK-specific inhibitor U0126 or PKC inhibitor staurosporine (STP) also down-regulated XIAP expression and induced apoptosis. Thus, our data suggest that apoptosis and down-regulation of XIAP induced by Dox exposure or serum starvation may be mediated through inactivation of the MEK/ERK and PKCalpha/beta pathways. In support of this we demonstrated that the cytotoxic effects of Dox when combined with U0126 or STP were enhanced, i.e., synergistic cytotoxic activities were demonstrated. The synergistic interaction of U0126 or STP with Dox was sequence- and concentration-dependent.
 ...
PMID:Inhibition of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase enhances chemotherapeutic effects on H460 human non-small cell lung cancer cells through activation of apoptosis. 1288 37

Cruciferous vegetable-derived isothiocyanates (ITCs; chemical structure: R-N=C=S) are highly effective in affording protection against chemically induced cancers in animal models. Here, we studied the antitumor effects of benzyl isothiocyanate (BITC; Ph-CH2-N=C=S), the predominant ITC compound in broccoli, on head and neck squamous cell carcinoma (HNSCC) cell lines. Proliferation, apoptosis and immunoblotting assays were used to determine the effects and mechanism of several ITCs on HNSCC cells. The IC50 for BITC (24 h treatment) in two of the HNSCC cell lines was approximately 22 and 17 micro M, respectively. Interestingly, phenyl isothiocyanate (PITC; Ph-N=C=S), which is a close structural analog of BITC but lacks a -CH2- spacer that links the aromatic ring to N=C=S moiety, did not result in significant killing of the HNSCC cells in this dose range. BITC (but not PITC) caused activation of caspase 3 and PARP cleavage. Within 20 min of treatment, BITC (but not PITC) induced a rapid activation of p38 MAPK. In addition, BITC (but not PITC) treatment resulted in the activation of p44/42 MAPK. Co-treatment with a specific p38 MAPK inhibitor, SB203580, or an inhibitor of the MEK/MAPK pathway, U0126, partially rescued cells from BITC-induced killing. Our results show that minor structural differences in ITCs can be crucial for the antiproliferative activity of ITCs and that BITC may be a promising chemopreventive as well as therapeutic agent in HNSCC.
 ...
PMID:Requirement of a carbon spacer in benzyl isothiocyanate-mediated cytotoxicity and MAPK activation in head and neck squamous cell carcinoma. 1289 7

Assessment of specific apoptosis and survival pathways implicated in anticancer drug action is important for understanding drug mechanisms and modes of resistance in order to improve the benefits of chemotherapy. In order to better examine the role of mitogen-activated protein kinases, including JNK and ERK, as well as the tumor suppressor p53, in the response of tumor cells to chemotherapy, we compared the effects on these pathways of three structurally and functionally distinct antitumor agents. Drug concentrations equal to 50 times the concentration required to reduce cell proliferation by 50% were used. Vinblastine, doxorubicin, or etoposide (VP-16) induced apoptotic cell death in KB-3 carcinoma cells, with similar kinetic profiles of PARP cleavage, caspase 3 activation, and mitochondrial cytochrome c release. All three drugs strongly activated JNK, but only vinblastine induced c-Jun phosphorylation and AP-1 activation. Inhibition of JNK by SP600125 protected cells from drug-induced cytotoxicity. Vinblastine caused inactivation of ERK whereas ERK was unaffected in cells exposed to doxorubicin or VP-16. Inhibition of ERK signaling by the MEK inhibitor, U0126, potentiated the cytotoxic effects of vinblastine and doxorubicin, but not that of VP-16. Vinblastine induced p53 downregulation, and chemical inhibition of p53 potentiated vinblastine-induced cell death, suggesting a protective effect of p53. In contrast, doxorubicin and VP-16 induced p53, and inhibition of p53 decreased drug-induced cell death, suggesting a pro-apoptotic role for p53. These results highlight the differential roles played by several key signal transduction pathways in the mechanisms of action of key antitumor agents, and suggest ways to specifically potentiate their effects in a context-dependent manner. In addition, the novel finding that JNK activation can occur without c-Jun phosphorylation or AP-1 activation has important implications for our understanding of JNK function.
 ...
PMID:The JNK, ERK and p53 pathways play distinct roles in apoptosis mediated by the antitumor agents vinblastine, doxorubicin, and etoposide. 1290 45

Vitamin D-binding protein-macrophage-activating factor (DBP-maf) is derived from serum vitamin D binding protein (DBP) by selective deglycosylation during inflammation. In the present study, we investigated the effect of DBP-maf on RAW 264.7 macrophages and the underlying intracellular signal transduction pathways. DBP-maf increased proapoptotic caspase-3, -8, and -9 activities and induced apoptosis in RAW 264.7 cells. However, DBP, the precursor to DBP-maf did not induce apoptosis in these cells. Cell cycle analysis of DBP-maf-treated RAW 264.7 cells revealed growth arrest with accumulation of cells in sub-G(0)/G(1) phase. We also investigated the role of mitogen-activated protein kinase (MAPK) pathways in the DBP-maf-induced apoptosis of RAW264.7 cells. DBP-maf increased the phosphorylation of p38 and JNK1/2, while it decreased the ERK1/2 phosphorylation. Treatment with the p38 MAPK inhibitor, SB202190, attenuated DBP-maf-induced apoptosis. PD98059, a MEK specific inhibitor, did not show a significant inhibition of apoptosis induced by DBP-maf. Taken together, these results suggest that the p38 MAPK pathway plays a crucial role in DBP-maf-mediated apoptosis of macrophages. Our studies indicate that, during inflammation DBP-maf may function positively by causing death of the macrophages when activated macrophages are no longer needed at the site of inflammation. In summary, we report for the first time that DBP-maf induces apoptosis in macrophages via p38 and JNK1/2 pathway.
 ...
PMID:Mitogen-activated protein kinase pathway mediates DBP-maf-induced apoptosis in RAW 264.7 macrophages. 1293 59

It is believed that bisphosphonates (BPs) induce apoptosis in cells such as myeloma cells, as they inhibit prenylation of G-proteins. However, the details of the apoptosis-inducing mechanism remain obscure. In the present study, we attempted to clarify the mechanism by which YM529, a new bisphosphonate, induces apoptosis. YM529 induced cell deaths in HL60 cells in a concentration-dependent manner. At that time, we observed an increase in Caspase-3 activity and morphological fragmentation of the nuclei. We could confirm that these cell deaths were evidence of apoptosis. The apoptosis induced by YM529 was not inhibited by the addition of farnesyl pyrophosphate (FPP), but was by the addition of geranylgeranyl pyrophosphate (GGPP). When we examined the survival signals at the time of apoptotic induction, we also observed that the administration of YM529 caused a remarkable decrease in the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). However, other survival signals such as nuclear factor kappa B (NF-kappaB), protein kinase B (Akt), and p38 mitogen-activated protein kinase (p38) exhibited no change. In addition, no quantitative change was observed in Bcl-2, which is an anti-apoptosis protein. It was also observed that apoptosis was induced when U0126, an MEK inhibitor, was added to the cells to inhibit ERK. These results suggest that YM529, the new bisphosphonate, induced apoptosis when inhibit GGPP synthase and consequently decreased the levels of phosphorylated ERK, which is a survival signal; moreover, during this process, there is no influence on NF-kappaB, Akt, p38, and Bcl-2. The results of this study also suggest that YM529 can be used as an anticancer agent, in addition to its use as a therapeutic agent to treat osteoporosis.
 ...
PMID:A new bisphosphonate, YM529 induces apoptosis in HL60 cells by decreasing phosphorylation of single survival signal ERK. 1367 34

Retinoids have great potential in the areas of cancer therapy and chemoprevention. 6-[3-(1-admantyl)]-4-hydroxyphenyl]-2-naphthalene carboxylic acid (CD437) is a conformationally restricted synthetic retinoid that has been reported to induce growth arrest and apoptosis in ovarian tumor cell lines but the entire mechanism for apoptotic induction has not been fully defined. We set out to identify the early events of CD437-induced apoptosis of the CA-OV-3 cell line and determine if these occur in a CA-OV-3 cell line resistant to CD437 (CA-CD437R). Using inhibitors for the MAP kinase cascade, we determined that MEK and p38 inhibitors could block CD437-induced apoptosis of the CA-OV-3 cell line. Moreover, treatment of CA-OV-3 and CA-CD437R cells with CD437 resulted in increased phosphorylation and activity of p38 independent of caspase-3 activation. Furthermore, p38 induced the phosphorylation of MEF2 in both CA-OV-3 and CA-CD437R cells after CD437 treatment. Finally, GFP-TR3 protein translocated to the cytosol and associated with mitochondria in both cell lines in response to CD437 treatment. This leads to depolarization of mitochondria and subsequent induction of apoptosis only in CA-OV-3 cells. These results identify a number of initial molecular events in the induction of apoptosis by CD437 in CA-OV-3 cells and demonstrate that the alteration in CA-CD437R cells, which results in resistance to CD437 maps downstream of these early events after TR3 translocation but prior to mitochondrial depolarization.
 ...
PMID:Early events in the induction of apoptosis in ovarian carcinoma cells by CD437: activation of the p38 MAP kinase signal pathway. 1450 18

Since ethacrynic acid (EA), an SH modifier as well as glutathione S-transferase (GST) inhibitor, has been suggested to induce apoptosis in some cell lines, its effects on a human colon cancer cell line DLD-1 were examined. EA enhanced cell proliferation at 20-40 microM, while it caused cell death at 60-100 microM. Caspase inhibitors did not block cell death and DNA ladder formation was not detected. Poly(ADP-ribose) polymerase, however, was cleaved into an 82-kDa fragment, different from an 85-kDa fragment that is specific for apoptosisis. The 82-kDa fragment was not recognized by antibody against PARP fragment cleaved by caspase 3. N-Acetyl-L-cysteine (NAC) completely inhibited EA-induced cell death, but 3(2)-t-butyl-4-hydroxyanisole or pyrrolidinedithiocarbamate ammonium salt did not. Glutathione (GSH) levels were dose-dependently increased in cells treated with EA and this increase was hardly affected by NAC addition. Mitogen-activated protein kinase (MAPK) kinase (MEK) 1, extracellular signal-regulated kinase (ERK) 1 and GST P1-1 were increased in cells treated with 25-75 microM EA, while c-Jun N-terminal kinase (JNK) 1 and p38 MAPK were markedly decreased by 100 microM EA. NAC repressed EA-induced alterations in these MAPKs and GST P1-1. p38 MAPK inhibitors, SB203580 and FR167653, dose-dependently enhanced EA-induced cell death. An MEK inhibitor, U0126, did not affect EA-induced cell death. These studies revealed that EA induced cell death concomitantly with a novel PARP fragmentation, but without DNA fragmentation. p38 MAPK was suggested to play an inhibitory role in EA-induced cell death.
 ...
PMID:Characterization of cell death induced by ethacrynic acid in a human colon cancer cell line DLD-1 and suppression by N-acetyl-L-cysteine. 1455 62


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>