Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.56 (caspase-3)
 35,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study demonstrates that Ha-rasVal12 oncogene overexpression sensitizes NIH/3T3 fibroblasts to lovastatin (LOV) cytotoxicity. This sensitization is through apoptosis, which was characterized by increasing CPP32 (caspase-3) activity and DNA fragmentation. Bcl-2 overexpression increased the resistance of the Ha-ras transformants to LOV and rescued the cells from apoptosis, further confirming that the LOV-sensitive cells died of apoptosis. Further analysis showed that Ha-ras activity inversely correlated with WAF1 activity. LOV treatment suppressed Ha-ras activity but induced WAF1 activity and disrupted the cell population in G0/G1 and S phases. The Ha-ras transformants expressing either dominant negative RasAsn17 or Raf-1CB4 showed reverted susceptibility to LOV. These data confirm the involvement of Ras and demonstrate that Raf-1 signalling is required for LOV-induced cell death. Taken together, the possible action of LOV-induced apoptosis is through suppressing Ha-ras activity and increasing WAF1 activity, which alters cell cycle progression and finally activates suppressed apoptotic pathway in a Fas/Fas-L- and p53-independent fashion.
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PMID:Ha-rasVal12 oncogene increases susceptibility of NIH/3T3 cells to lovastatin. 967 86

Medulloblastoma is a malignant cerebellar tumor usually manifesting in childhood. We have previously shown that blocking the mevalonate pathway with lovastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, inhibits medulloblastoma proliferation and induces apoptosis in vitro. The underlying mechanism may involve blocking post-translational modification of important mitogenic signal-transduction proteins. We show that p21 ras processing is blocked by lovastatin, suggesting that inhibition of isoprenylation may be important in lovastatin-induced apoptosis. To test this hypothesis, manumycin A, an antibiotic which inhibits farnesyl protein transferase and thus farnesylation, was administered to 4 medulloblastoma cell lines in vitro. We found that blocking protein farnesylation with manumycin A was followed by apoptosis in a time- and dose-dependent manner. However, cell death induced by manumycin A was uniformly more rapid and efficient, requiring only 12 to 24 hr of treatment, than lovastatin-induced apoptosis, which required 36 to 96 hr (depending on the cell line tested). In addition, unlike lovastatin, which caused cell-cycle arrest in G1 phase and HMG-CoA reductase gene up-regulation, manumycin A had no effect on the cell cycle and resulted in down-regulation of HMG-CoA reductase gene expression. In both lovastatin- and manumycin A-treated cells, cellular cysteine protease precursor (CPP32) was activated, confirming the occurrence of apoptosis.
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PMID:Apoptosis of medulloblastoma cells in vitro follows inhibition of farnesylation using manumycin A. 1039 61

The inability of certain neoplastic populations to undergo Fas-mediated death by immune effector mechanisms may confer a selective survival advantage, which may contribute to tumor escape. In this study, we examined the role of Fas-mediated lysis in a human-antigen (Ag)-specific cytotoxic T lymphocyte (CTL)/colon carcinoma cell model, and the regulation of the lytic phenotype by interferon gamma (IFNgamma). Previously, we have identified mutated ras peptides reflecting the valine-for-glycine substitution at position 12 as unique HLA-A2-restricted, CD8+ CTL neo-epitopes. Peptide-specific CTL, established from both normal and carcinoma-bearing individuals, lysed in vitro a HLA-A2+ primary colon adenocarcinoma cell line, SW480, harboring the naturally occurring ras mutation. Pretreatment of SW480 cells with IFN-gamma was necessary to promote efficient Ag-specific CTL killing, although the mechanisms by which IFNgamma influenced the lytic outcome remains to be elucidated. Here, we show, by phenotypic analysis of SW480 cells, a significant up-regulation of HLA-A2, ICAM-1 and Fas molecules after IFNgamma pretreatment, which paralleled their sensitivity to lysis with anti-Fas stimuli. Moreover, nearly half of the lytic response to IFNgamma-treated SW480 cells was inhibited by neutralizing anti-Fas or anti-Fasligand (FasL) mAb, revealing for the first time an important functional role for Fas/FasL interactions in carcinoma cell killing by human Ag-specific CTL. mAb against HLA-A2, ICAM-1, the alpha T cell receptor (TCR) and Fas molecules inhibited lysis; however, if these CTL were preactivated to express functional FasL and then used as effectors, only anti-Fas mAb efficiently blocked lysis. IFNgamma also increased pro-caspase-3 protein expression and its subsequent activation in SW480 cells following Ag-specific CTL attack. Peptide-based caspase inhibitors blocked both caspase-3 activation and CTL-mediated lysis. Overall, these data suggested that IFNgamma (a) facilitated both Ag-dependent and Ag-independent events as a prerequisite for efficient CTL/target interactions, FasL up-regulation and triggering of Fas-dependent, as well as Fas-independent lysis (perforin); and (b) enhanced or restored a Fas-sensitive phenotype in SW480 cells, reflecting modulation of cell-surface and intracellular elements of the Fas pathway. Thus, IFNgamma may play an important role in the regulation of a human neoplastic cell death phenotype, which may have implications for our understanding of the processes of both tumor evasion and tumor regression following Ag-specific CTL attack.
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PMID:Influence of interferon gamma on modulation of Fas expression by human colon carcinoma cells and their subsequent sensitivity to antigen-specific CD8+ cytotoxic T lymphocyte attack. 1094 2

We obtained evidence that increased stability of nucleophosmin/B23 is involved in antiapoptotic effect of ras during serum deprivation. Nucleophosmin/B23 in serum-deprived (0% serum) NIH-3T3 cells was found to be highly unstable with a half-life less than 4 h. In contrast, nucleophosmin/B23 in serum-deprived ras-transformed (RAS-3T3) cells was as stable as that in serum-supplemented NIH-3T3 or RAS-3T3 cells. Treatment of RAS-3T3 cells with nucleophosmin/B23 antisense oligomer significantly potentiated the apoptosis induced by serum deprivation. Much less caspase-3 activity was noted in the lysate derived from serum-deprived RAS-3T3 cells compared with that in the lysate of serum-deprived NIH-3T3 cells. Cell permeable caspase-3 inhibitor added in the medium blocked the decrease of nucleophosmin/B23 and apoptosis induced by serum deprivation in NIH-3T3 cells. The inhibitor, on the other hand, promoted significant decrease of nucleolin/C23 in NIH-3T3 cells during serum deprivation. Unlike nucleolin/C23, down-regulation of nucleophosmin/B23 was thus not proliferation-dependent but caspase-3- and apoptosis-dependent. Our results indicate important relationships among ras, nucleophosmin/B23, activation of caspase-3, and induction of apoptosis.
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PMID:Increased stability of nucleophosmin/B23 in anti-apoptotic effect of ras during serum deprivation. 1112 22

Epidemiologic studies have documented a 40-50% reduction in incidence of colorectal cancer in individuals taking nonsteroidal antiinflammatory drugs (NSAIDs). Since NSAIDs are known to inhibit cyclooxygenases (COX-1, COX-2), the basic mechanism of their antitumor effects is conceivably the altered metabolism of arachidonic acid and, subsequently, prostaglandins (PGs). Although COX-2, the inducible isoform, is regularly expressed at low levels in colonic mucosa, its activity increases dramatically following mutation of the APC (adenomatous polyposis coli) gene suggesting that beta-catenin/T-cell factor mediated Wnt-signaling activity may regulate COX-2 gene expression. In addition, hypoxic conditions and sodium butyrate exposure may also contribute to COX-2 gene transcription in human cancers. The development of selective COX-2 inhibitors has made it possible to further evaluate the role of COX-2 activity in colorectal carcinogenesis. To date, at least five mechanisms by which COX-2 contributes to tumorigenesis and the malignant phenotype of tumor cells have been identified, including: (1) inhibition of apoptosis; (2) increased angiogenesis; (3) increased invasiveness; (4) modulation of inflammation/immuno-suppression; and (5) conversion of procarcinogens to carcinogens. A clear positive correlation between COX-2 expression and inhibition of apoptosis has been established, associated with increased PGE2 levels resulting in modulation of pro- and anti-apoptotic factors (e.g., bcl-2, MAKs/ras, caspase-3, Par-4). In terms of angiogenesis and invasiveness, COX-2 activity was found to increase the expression of growth factors (e.g., VDEG, PDGF, bFGF) and matrix metalloproteinases (MMPs). Since COX-2 inhibitors have been demonstrated to interfere with tumorigenesis and apoptosis, COX-2 and its gene product may be attractive targets for therapeutic and chemoprotective strategies in colorectal cancer patients. This may lead to new perspectives that by controlling the cancer phenotype, rather than attempting to eradicate all affected cells, may provide significant benefits to the cancer patient.
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PMID:Cyclooxygenase-2: a novel target for cancer chemotherapy? 1146 77

(E)-(1S,4S,10S,21R)-7-[(Z)-ethylidene]-4,21-diisopropyl-2-oxa-12,13-dithia-5,8,20,23-tetraazabicyclo[8,7,6]-tricos-16-ene-3,6,9,19,22-pentanone (FR901228), a natural anticancer depsipeptide, induces apoptosis of ras-transformed 10T1/2 cells whereas it induces growth arrest of nontransformed counterpart cells in G0/G1 phase of the cell cycle. Our study of the effect of FR901228 treatment on intracellular signaling pathways reveals a discriminating activity of FR901228 to regulate signaling cascades differently in ras-transformed 10T1/2 cells and nontransformed counterpart cells. Induction of apoptosis of ras-transformed cells by FR901228 correlates with suppression of the extracellular signal-regulated kinase (ERK) signaling pathway through reduction of Raf expression and deactivation of Mek and Erk, inhibition of the phosphoinositide-3 kinase (PI3-K) pathway indexed by suppression of Akt activity, suppression of p38 activity, and activation of caspase-3. Expression of p21(Cip1) is not induced in ras-transformed cultures undergoing apoptosis induced by FR901228. In contrast, FR901228 induces p21(Cip1) expression in nontransformed counterpart cultures growth-arrested in G0/G1 that is also accompanied by moderate induction of the kinase activities of Raf, Mek, Erk, and Akt, but not accompanied by activation of caspase-3 or changes in p38 activity. Our study indicates a potential value of FR901228 in the treatment of cancer cells involving aberrant regulation of Ras through preferential induction of the caspase cascade and suppression of the ERK, PI3-K, and p38 pathways.
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PMID:Differential modulation of signaling pathways and apoptosis of ras-transformed 10T1/2 cells by the depsipeptide FR901228. 1186 95

Previously, we designed a ribozyme that targets the H-ras oncogene at the 12th codon mutation site (Chang et al., 1997). Ribozymes have antisense molecule and site-specific ribonuclease potential. In this study, an adenoviral vector was used to transduce the H-ras ribozyme into laryngeal cancer cells (HEp-2). This served to downregulate the H-ras gene expression in which this ribozyme performed antisense activity due to HEp-2 cells containing wild-type alleles in the 12th H-ras codon. Together, our data demonstrated that the recombinant adenovirus encoding H-ras ribozyme can be broadly regarded as a cytotoxic gene therapy in laryngeal cancer cells regardless of containing wild-type or mutant ras gene. In addition, the mechanism through which the H-ras ribozyme inhibited tumor growth was apoptosis and involved both caspase- and mitochondria-mediated pathways. The activators caspase-8 and -9 as well as the effector caspase-3 in the induction phase of apoptosis and the substrate PARP of caspase-3 in the execution phase were activated 48h following the H-ras ribozyme treatment. Mitochondrial events characterized by the production of superoxide anion and the release of cytochrome c started at 24h. Mitochondrial transmembrane potential loss occurred 48h after the ribozyme treatment. However, Bcl-2 delayed cytochrome c release to the cytosol, but it could not protect the apoptosis effect, suggesting that cytochrome c release from mitochondria may not play a role in H-ras ribozyme-induced apoptosis.
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PMID:Recombinant adenovirus encoding H-ras ribozyme induces apoptosis in laryngeal cancer cells through caspase- and mitochondria-dependent pathways. 1241 27

Efforts have been made to develop a chemoprevention strategy that selectively triggers apoptosis in malignant cancer cells. Previous studies showed that capsaicin, the major pungent ingredient of red pepper, had differential effect between normal and transformed cells. As an approach to unveil the molecular mechanism by which capsaicin selectively induces apoptosis in transformed cells, we investigated the effect of capsaicin in nontransformed and ras-transformed cells of a common origin: parental (MCF10A) and H-ras-transformed (H-ras MCF10A) human breast epithelial cells. Here, we show that capsaicin selectively induces apoptosis in H-ras-transformed cells but not in their normal cell counterparts. The capsaicin-induced apoptosis, which is dependent on ras transformation, involves the activity of DEVDase (caspase-3 like). In H-ras MCF10A cells, capsaicin treatment markedly activated c-Jun N-terminal protein kinase (JNK)-1 and p38 matigen-activated protein kinase (MAPK) while it deactivated extracellular signal-regulated protein kinases (ERKs). The use of kinase inhibitors and overexpression of dominant-negative forms of MAPKs demonstrated a role of JNK-1 and p38, but not that of ERKs, in apoptosis induced by capsaicin in H-ras-transformed MCF10A cells. Based on the present study, we propose that capsaicin selectively induces apoptosis through modulation of ras-downstream signaling molecules in ras-activated MCF10A cells. Taken in conjunction with the fact that uncontrolled ras activation is probably the most common genetic defect in human cancer cells, our finding may be critical to the chemopreventive potential of capsaicin and for developing a strategy to induce tumor cell-specific apoptosis.
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PMID:Roles of JNK-1 and p38 in selective induction of apoptosis by capsaicin in ras-transformed human breast epithelial cells. 1247 62

Nitric oxide (NO) generated by either endothelial nitric oxide synthase (eNOS) or inducible nitric oxide synthase (iNOS) may be involved in prostate tumorigenesis through the inhibition of reactive oxygen species (ROS)-induced apoptosis. Multicellular DU-145 prostate tumor spheroids endogenously generated NO that paralleled the production of ROS. With increasing spheroid size, eNOS expression was downregulated, whereas an upregulation of iNOS expression was observed. In parallel, NO generation declined, as evaluated by the NO indicator diaminofluorescein-2 diacetate (DAF-2DA), suggesting that NO generation in DU-145 tumor spheroids is mainly mediated by eNOS. Elevation of ROS by treatment of tumor spheroids with either buthionine sulfoximine (BSO) or hydrogen peroxide resulted in upregulation of eNOS, whereas iNOS was downregulated. Furthermore, eNOS expression was increased by epidermal growth factor (EGF) in a redox-sensitive manner. Upregulation of eNOS after treatment with hydrogen peroxide was apparently transduced through receptor tyrosine kinase signaling pathways since it was abolished by the protein kinase C (PKC) inhibitor bisindolylmaleimide-1 (BIM-1), the p21(ras) inhibitor S-trans-trans-farnesylthiosalicylic acid (FTS), the c-Raf inhibitor ZM 336372 and PD98059, which inhibits ERK1/2 activation. Endogenous NO may serve to escape from oxidative stress-induced apoptosis since treatment of tumor spheroids with the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl imidazoline-1-oxyl 3-oxide (carboxy-PTIO) as well as the NO synthase inhibitor N-omega-amino-L-arginine (L-NAA) increased cleaved caspase-3. Consequently, lowering intracellular NO levels with either L-NAA or PTIO significantly raised ROS levels, indicating that endogenously generated NO may play a role as a ROS scavenger, thereby protecting exponentially growing tumor spheroids from ROS-induced apoptosis.
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PMID:Reactive oxygen species-mediated regulation of eNOS and iNOS expression in multicellular prostate tumor spheroids. 1256 50

Mistletoe extracts are used as alternative cancer treatment in addition to standard chemotherapy and radiation treatment and have an immunostimulatory and pain-relieving effect. A direct antitumour effect of mistletoe extracts against tumour cells of lymphoid origin has been linked to the D-galactoside-specific mistletoe lectin I. In this study, we investigated the cellular effect of bacterially expressed, recombinant mistletoe lectin alone or in combination with ionising radiation in a genetically defined p53-wild-type and p53-deficient E1A/ras-transformed murine tumour cells system. Downregulation of the proliferative activity and cell killing by recombinant mistletoe lectin occurred in a clear dose response (0.1-1 ng ml(-1)). Induction of apoptosis was p53-independent, but apoptosis-associated factor-1-dependent. Cellular treatment with lectin in combination with ionising radiation resulted in both p53-wild-type and p53-deficient tumour cells in an at least additive, antiproliferative effect and enhanced activation of caspase-3. Combined treatment with ionising radiation and lectin revealed a similar cytotoxic effect in human, p53-mutated adenocarcinoma cells. Thus, recombinant mistletoe lectin alone and in combination with ionising radiation bypasses often prevalent apoptotic deficiencies in treatment-resistant tumour cells.
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PMID:Recombinant mistletoe lectin induces p53-independent apoptosis in tumour cells and cooperates with ionising radiation. 1277 96


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