Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.4.2.30 (PARP)
13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the chemopreventive role of curcumin in gastrointestinal cancers by studying the regulation of proliferation and apoptosis in gastric (KATO-III) and colon (HCT-116) cancer cells. Curcumin inhibited cell proliferation and induced G2/M arrest in HCT-116 cells. Investigation of the levels of cyclins E, D and B by immunoblot analysis showed cyclin B level was unaffected, whereas cyclin D and E levels declined with curcumin in both cell lines. Investigation of cyclin-dependent kinases, Cdk2 and Cdc2, showed activity of Cdc2, but not Cdk2, increased markedly in response to curcumin. In both cell lines, immunoblot analysis indicated that curcumin caused induction of apoptosis as evidenced by cleavage of PARP, caspase-3, and reduction in Bcl-XL levels. Curcumin also stimulated the activity of caspase-8, which initiates Fas signalling pathway of apoptosis. Curcumin therefore appears to exert its anticarcinogenic properties by inhibiting proliferation and inducing apoptosis in certain gastric and colon cancer cells.
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PMID:Curcumin induced modulation of cell cycle and apoptosis in gastric and colon cancer cells. 1139 78

Carbonyl compounds with diverse carbon skeletons may be differentially related to the pathogenesis of vascular diseases. In this study, we compared intracellular signals delivered into cultured human umbilical vein endothelial cells (HUVECs) by glyoxal (GO) and methylglyoxal (MGO), which differ only by a methyl group. Depending on their concentrations, GO and MGO promoted phosphorylations of ERK1 and ERK2, which were blocked by the protein-tyrosine kinase (PTK) inhibitors herbimycin A and staurosporine, thereby being PTK-dependent. GO and MGO also induced phosphorylations of JNK, p38 MAPK, and c-Jun, either PTK-dependently (GO) or -independently (MGO). Next, we found that MGO, but not GO, induced degradation of poly(ADP-ribose) polymerase (PARP) as the intracellular substrate of caspase-3. Curcumin and SB203580, which inhibit JNK and p38 MAPK signaling pathways, but not herbimycin A/staurosporine, prevented the MGO-induced PARP degradation. We then found that MGO, but not GO, reduced the intracellular glutathione level, and that cysteine, but not cystine, inhibited the MGO-mediated activation of ERK, JNK, p38 MAPK, or c-Jun more extensively than did lysine or arginine. In addition, all the signals triggered by GO and MGO were blocked by amino guanidine (AG), which traps carbonyls. These results demonstrated that GO and MGO triggered two distinct signal cascades, one for PTK-dependent control of ERK and another for PTK-independent redox-linked activation of JNK/p38 MAPK and caspases in HUVECs, depending on the structure of the carbon skeleton of the chemicals.
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PMID:Glyoxal and methylglyoxal trigger distinct signals for map family kinases and caspase activation in human endothelial cells. 1142 86

Pharmacologically safe compounds that can inhibit the proliferation of tumor cells have potential as anticancer agents. Curcumin, a diferuloylmethane, is a major active component of the food flavor turmeric (Curcuma longa) that has been shown to inhibit the proliferation of a wide variety of tumor cells. The apoptotic intermediates through which curcumin exhibits its cytotoxic effects against tumor cells are not known, and the participation of antiapoptotic proteins Bcl-2 or Bcl-xl in the curcumin-induced apoptosis pathway is not established. In the present report we investigated the effect of curcumin on the activation of the apoptotic pathway in human acute myelogenous leukemia HL-60 cells and in established stable cell lines expressing Bcl-2 and Bcl-xl. Curcumin inhibited the growth of HL-60 cells (neo) in a dose- and time-dependent manner, whereas Bcl-2 and Bcl-xl-transfected cells were relatively resistant. Curcumin activated caspase-8 and caspase-3 in HL-60 neo cells but not in Bcl-2 and Bcl-xl-transfected cells. Similarly, time-dependent poly(ADP)ribose polymerase (PARP) cleavage by curcumin was observed in neo cells but not in Bcl-2 and Bcl-xl-transfected cells. Curcumin treatment also induced BID cleavage and mitochondrial cytochrome c release in neo cells but not in Bcl-2 and Bcl-xl-transfected cells. In neo HL-60 cells, curcumin also downregulated the expression of cyclooxygenase-2. Because DN-FLICE blocked curcumin-induced apoptosis, caspase-8 must play a critical role. Overall, our results indicate that curcumin induces apoptosis through mitochondrial pathway involving caspase-8, BID cleavage, cytochrome c release, and caspase-3 activation. Our results also suggest that Bcl-2 and Bcl-xl are critical negative regulators of curcumin-induced apoptosis.
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PMID:Curcumin (diferuloylmethane) induces apoptosis through activation of caspase-8, BID cleavage and cytochrome c release: its suppression by ectopic expression of Bcl-2 and Bcl-xl. 1175 35

We have shown earlier that heat shock renders human colon cancer cells resistant to curcumin-induced apoptosis, but the contribution of individual heat shock proteins (hsps) to this resistance has not been tested. High expression of hsp27 and hsp70 in breast, endometrial and gastric cancers has been associated with metastasis, poor prognosis and resistance to chemo- or radiotherapy. In this study, SW480 cells were transfected with hsp70 cDNA in either the sense or antisense orientation and stable clones were selected and tested for their sensitivity to curcumin. The cells were protected from curcumin-induced cell death by hsp70 while cells harboring antisense hsp70 (Ashsp70) were highly sensitive to curcumin. Curcumin-induced nuclear condensation was less in hsp70 but more in Ashsp70 cells when compared with control vector-transfected cells. Loss of mitochondrial transmembrane potential induced by curcumin was further accelerated by antisense hsp70 expression and hsp70 restored it partly. Ashsp70 cells released more cytochrome c, AIF and Smac from mitochondria upon curcumin treatment than control cells. hsp70 partly prevented the release of AIF but not the other proteins. Activation of caspases 3 and 9 induced by curcumin was also inhibited by hsp70, whereas more activation could be seen in Ashsp70 cells, although caspase 8 activation was unaffected by changes in hsp70 expression. Curcumin-induced cleavage of PARP and DFF45 was inhibited by hsp70 but enhanced in Ashsp70 cells. The present study demonstrates the potential of hsp70 in protecting SW480 cells from curcumin-induced apoptosis and highlights that silencing the expression of hsp70 is an effective approach to augment curcumin-based therapy in cancers that are resistant due to hsp70 expression.
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PMID:Ectopic expression of Hsp70 confers resistance and silencing its expression sensitizes human colon cancer cells to curcumin-induced apoptosis. 1460 99

Methylglyoxal (MG) is a reactive dicarbonyl compound endogenously produced mainly from glycolytic intermediates. Elevated MG levels in diabetes patients are believed to contribute to diabetic complications. MG is cytotoxic through induction of apoptosis. Curcumin, the yellow pigment of Curcuma longa, is known to have antioxidant and anti-inflammatory properties. In the present study, we examined the effect of curcumin on apoptotic biochemical events caused by incubation of ESC-B5 cells with MG. Curcumin inhibited the MG-induced DNA fragmentation, caspase-3 activation, cleavage of PARP, mitochondrial cytochrome c release, and JNK activation. Importantly, curcumin also inhibited the MG-stimulated increase of reactive oxygen species (ROS) in these cells. In addition, we demonstrated that curcumin prevented the MG-induced apoptosis of mouse blastocysts isolated from pregnant mice. Moreover, curcumin significantly reduced the MG-mediated impairment of blastocyst development from mouse morulas. The results support the hypothesis that curcumin inhibits MG-induced apoptosis in mouse ESC-B5 cells and blastocysts by blocking ROS formation and subsequent apoptotic biochemical events.
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PMID:Curcumin prevents methylglyoxal-induced oxidative stress and apoptosis in mouse embryonic stem cells and blastocysts. 1588 45

Methylglyoxal (MG) is a reactive dicarbonyl compound endogenously produced mainly from glycolytic intermediates. Elevated MG levels in diabetes patients are believed to contribute to diabetic complications. MG is cytotoxic through induction of apoptosis. Curcumin, the yellow pigment of Curcuma longa, is known to have antioxidant and anti-inflammatory properties. In the present study, we investigated the effect of curcumin on MG-induced apoptotic events in human hepatoma G2 cells. We report that curcumin prevented MG-induced cell death and apoptotic biochemical changes such as mitochondrial release of cytochrome c, caspase-3 activation, and cleavage of PARP (poly [ADP-ribose] polymerase). Using the cell permeable dye 2',7'-dichlorofluorescein diacetate (DCF-DA) as an indicator of reactive oxygen species (ROS) generation, we found that curcumin abolished MG-stimulated intracellular oxidative stress. The results demonstrate that curcumin significantly attenuates MG-induced ROS formation, and suggest that ROS triggers cytochrome c release, caspase activation, and subsequent apoptotic biochemical changes.
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PMID:Curcumin inhibits ROS formation and apoptosis in methylglyoxal-treated human hepatoma G2 cells. 1596 83

Human mantle cell lymphoma (MCL), an aggressive B cell non-Hodgkin's lymphoma, is characterized by the overexpression of cyclin D1 which plays an essential role in the survival and proliferation of MCL. Because of MCL's resistance to current chemotherapy, novel approaches are needed. Since MCL cells are known to overexpress NF-kappaB regulated gene products (including cyclin D1), we used curcumin, a pharmacologically safe agent, to target NF-kappaB in a variety of MCL cell lines. All four MCL cell lines examined had overexpression of cyclin D1, constitutive active NF-kappaB and IkappaB kinase and phosphorylated forms of IkappaBalpha and p65. This correlated with expression of TNF, IkappaBalpha, Bcl-2, Bcl-xl, COX-2 and IL-6, all regulated by NF-kappaB. On treatment of cells with curcumin, however, downregulated constitutive active NF-kappaB and inhibited the consitutively active IkappaBalpha kinase (IKK), and phosphorylation of IkappaBalpha and p65. Curcumin also inhibited constitutive activation of Akt, needed for IKK activation. Consequently, the expression of all NF-kappaB-regulated gene products, were downregulated by the polyphenol leading to the suppression of proliferation, cell cycle arrest at the G1/S phase of the cell cycle and induction of apoptosis as indicated by caspase activation, PARP cleavage, and annexin V staining. That NF-kappaB activation is directly linked to the proliferation of cells, is also indicated by the observation that peptide derived from the IKK/NEMO-binding domain and p65 suppressed the constitutive active NF-kappaB complex and inhibited the proliferation of MCL cells. Constitutive NF-kappaB activation was found to be due to TNF, as anti-TNF antibodies inhibited both NF-kappaB activation and proliferation of cells. Overall, our results indicate that curcumin inhibits the constitutive NF-kappaB and IKK leading to suppression of expression of NF-kappaB-regulated gene products that results in the suppression of proliferation, cell cycle arrest, and induction of apoptosis in MCL.
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PMID:Curcumin (diferuloylmethane) inhibits constitutive NF-kappaB activation, induces G1/S arrest, suppresses proliferation, and induces apoptosis in mantle cell lymphoma. 1602 83

Curcumin, the yellow pigment in the spice turmeric, has potent chemopreventive activities that involve diverse molecular pathways. It is widely believed that curcumin pro-apoptotic properties are mediated by downregulation of NF kappa B (NFkappaB). The p65/RelA subunit of NFkappaB may influence cell death, in part by activation of NFkappaB anti-apoptotic target genes including X-linked inhibitor of apoptosis (XIAP), A20, bcl-xL and inhibition of sustained activation of c-Jun N-terminal kinase (JNK). We have shown previously that curcumin inhibits NFkappaB, activates JNK and promotes apoptosis in HCT116 colorectal cancer cells. Here, we show that forced overexpression of p65 does not affect curcumin-induced JNK activation. Indeed, overexpression of p65 enhanced curcumin-mediated apoptosis as assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay and poly(ADP-ribose) polymerase (PARP) cleavage. This potentiating effect of p65 upon curcumin-mediated apoptosis was reversed by transfection of cells with an IkappaB super-repressor (DeltaNIkappaB). Curcumin treatment inhibited expression of NFkappaB anti-apoptotic target genes in mock-transfected and in p65-overexpressing HCT116 cells, although expression levels remained higher in the latter. Taken together, these results show that curcumin-mediated activation of JNK or induction of apoptosis does not require inhibition of p65. Furthermore, curcumin/p65 synergy in promotion of apoptosis cannot be attributed to active repression of NFkappaB anti-apoptotic genes.
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PMID:Overexpression of p65/RelA potentiates curcumin-induced apoptosis in HCT116 human colon cancer cells. 1649 2

Curcumin has been shown to possess variety of biological functions including anti-tumor activity. The mechanism by which curcumin inhibit cell proliferation remains poorly understood. In the present report, we investigated the effect of curcumin on the activation of apoptotic pathway in T-cell acute lymphoblastic leukemia (T-ALL) malignant cells. Our data demonstrate that curcumin causes dose dependent suppression of proliferation in several T cell lines. Curcumin treatment causes the de-phosphorylation/inactivation of constitutively active AKT, FOXO transcription factor and GSK3. Curcumin also induces release of cytochrome c accompanied by activation of caspase-3 and PARP cleavage. In addition, zVAD-fmk, a universal inhibitor of caspases, prevents caspase-3 activation and abrogates cell death induced by curcumin treatment. Finally, treatment of T-ALL cells with curcumin down-regulated the expression of inhibitor of apoptosis protein (IAPs). Taken together, our finding suggest that curcumin suppresses constitutively activated targets of PI3'-kinase (AKT, FOXO and GSK3) in T cells leading to the inhibition of proliferation and induction of caspase-dependent apoptosis.
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PMID:Curcumin induces apoptosis via inhibition of PI3'-kinase/AKT pathway in acute T cell leukemias. 1650 62

Curcumin, the yellow pigment of Curcuma longa, is known to have antioxidant and anti-inflammatory properties, as well as their ability to either induce or prevent cell apoptosis. However, the precise molecular mechanisms of these effects are unknown. Here, we demonstrate that curcumin can induce apoptotic changes, including JNK activation, caspase-3 activation, and cleavage of PARP and PAK2, at treatment concentrations lower than 25 microM in human osteoblast cells. In contrast, treatment with 50-200 microM of curcumin does not induce apoptosis, but rather triggers necrotic cell death in human osteoblasts. Using the cell permeable dye 2',7'-dichlorofluorescin diacetate (DCF-DA) as an indicator of reactive oxygen species (ROS) generation, we found that while treatment with 12.5-25 microM curcumin directly increased intracellular oxidative stress, 50-200 microM curcumin had far less effect. Pretreatment of cells with N-acetyl cysteine or alpha-tocopherol, two well known ROS scavengers, attenuated the intracellular ROS levels increases and converted the apoptosis to necrosis induced by 12.5-25 microM curcumin. Moreover, we observed a dose-dependent decrease in intracellular ATP levels after treatment of osteoblast cells with curcumin and pretreatment of cells with antimycin or 2-deoxyglucose to cause ATP depletion significantly converted 12.5-25 microM curcumin-induced apoptosis to necrosis, indicating that ATP (a known mediator of apoptotic versus necrotic death) is most likely involved in the switching mechanism. Overall, our results signify that curcumin dosage treatment determines the possible effect on ROS generation, intracellular ATP levels, and cell apoptosis or necrosis in osteoblast cells.
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PMID:Dosage effects of curcumin on cell death types in a human osteoblast cell line. 1662 71


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