Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Poly(ADP-ribose) polymerase 1 (PARP-1) is a nuclear zinc finger DNA-binding protein that is implicated in the repair of DNA damage. Inhibition of PARP-1 through genetic knockouts causes cells to become hypersensitive to various chemotherapeutic agents. We tested the chemopotentiating ability of the PARP-1 inhibitor, CEP-6800, when used in combination with temozolomide (TMZ), irinotecan (camptothecin or SN38), and cisplatin against U251MG glioblastoma, HT29 colon carcinoma, and Calu-6 non-small cell lung carcinoma xenografts and cell lines, respectively. Exposure of tumor cells to TMZ, camptothecin (or SN38), and cisplatin before, or in the presence of, CEP-6800 significantly increased the onset and the magnitude of DNA damage, the duration for cells to effect repair, and the onset, duration, or fraction of cells arrested at the G(2)/M boundary. In addition, in vivo biochemical efficacy studies with CEP-6800 showed that it was able to attenuate irinotecan- and TMZ-induced poly(ADP-ribose) accumulation in LoVo and HT29 xenografts, respectively. Treatment of CEP 6800 (30 mg/kg) with TMZ (17 and 34 mg/kg) resulted in 100% complete regression of U251MG tumors by day 28 versus 60% complete regression caused by TMZ alone. CEP-6800 (30 mg/kg) in combination with irinotecan (10 mg/kg) resulted in a 60% inhibition of HT29 tumor growth versus irinotecan alone by day 33. The combination therapy of cisplatin (5 mg/kg) with CEP-6800 (30 mg/kg) caused a 35% reduction in Calu-6 tumor growth versus cisplatin alone by day 28. These data suggest that CEP-6800 could be used as a chemopotentiating agent with a variety of clinically effective chemotherapeutic agents.
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PMID:Chemopotentiation of temozolomide, irinotecan, and cisplatin activity by CEP-6800, a poly(ADP-ribose) polymerase inhibitor. 1270 Feb 81

Genistein, biochanin-A, and daidzein, the predominant soy isoflavones, have been reported to lower the risk of cancer, but it is not known whether they protect against human hepatoma cancer. This study was designed to investigate their effects on cell growth, the cell cycle, and apoptosis induction in the human hepatoma cell lines, HepG2, Hep3B, Huh7, PLC, and HA22T. Genistein, biochanin-A, and daidzein inhibited growth of all five lines in a dose-dependent manner. DNA fragmentation studies and the TUNEL assay demonstrated that isoflavones caused tumor cell death by induction of apoptosis. Activation of caspase-3 and cleavage of the caspase-3 substrate, poly(ADP-ribose)polymerase, was seen in hepatoma cells after 24 hours' exposure to isoflavones. In addition, isoflavone cytotoxicity correlated with downregulation of Bcl-2 and Bcl-XL expression. Synergistic effects of the three isoflavones were observed on cell growth inhibition, apoptosis induction, and anti-apoptotic protein expression. Flow cytometry showed that genistein, but not biochanin-A or daidzein, induced progressive and sustained accumulation of hepatoma cancer cells in the G2/M phase as a result of inhibition of Cdc2 kinase activity. Coapplication of caffeine prevented this cell cycle arrest, but not apoptosis, showing that cell cycle arrest was not necessary for apoptosis. Furthermore, the isoflavones combination also had a significant tumor-suppressive effect in nude mice. These results suggest that isoflavones might be promising agents for the treatment of human hepatoma.
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PMID:Effects of soy isoflavones on apoptosis induction and G2-M arrest in human hepatoma cells involvement of caspase-3 activation, Bcl-2 and Bcl-XL downregulation, and Cdc2 kinase activity. 1279 11

Poly(ADP-ribosyl)ation plays important roles in cellular DNA repair mechanisms as well as in cellular proliferation and genomic stability. Four carcinoma cell lines, LNCaP, PC-3, C4-2 and MatLu, and one prostate epithelial cell line, PNT1A, were tested using the H10 antibody to poly(ADP-ribose) by Western blotting and FACS analysis for basal and activated (10 mM H2O2) PARP activity. In both analyses, higher levels of basal polymer were present in the LNCaP cell line than in the prostate epithelial cell line or the MatLu cell an line. LNCaP cells demonstrated greater than 90% positive analyzed cells in FACS analysis both before and after treatment with H2O2. PNT1A epithelial cells demonstrated evidence of polymer presence only after treatment with H2O2. Microsatellite instability due to increased oxidative damage in tumor cells has been proposed as a means for accumulation of genetic changes. As oxidative stress can stimulate poly(ADP-ribose) reactions, an increased presence of the polymer may indicate a high level of oxidative damage occurring in the tumor cells, contributing to higher levels of genetic instability towards progression.
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PMID:Intrinsic presence of poly (ADP-ribose) is significantly increased in malignant prostate compared to benign prostate cell lines. 1282 Apr 12

CHS 828, a novel cyanoguanidine, represents a new class of drugs for cancer therapy, with an unknown primary mechanism of action. It is generally known that anticancer drugs induce p53 response thereby triggering cell cycle arrest or apoptosis. We investigated the effect of CHS 828 on p53 response in normal and tumor cells and compared this effect with that exerted by conventional anticancer drugs. After 24 h of treatment with CHS 828, we observed a dose-dependent up-regulation of wild type (WT) p53 protein in human breast carcinoma MCF-7 cells as well as in normal human and mouse fibroblasts. The highest p53 increase was observed at 300 nM to 1 microM CHS 828. CHS 828 induced phosphorylation of p53 protein at Ser-15 in normal cells. However, the drug failed to induce p53 protein in mouse cells in which the poly(ADP-ribose)-1 gene (PARP-1) was disrupted even at a 30-fold higher dose and after prolonged treatment. Combined treatment of PARP-1 -/- cells by multidrug resistance modulators did not alter p53 expression. CHS 828 inhibited cell proliferation and DNA replication in the tested cells. Interestingly, DNA synthesis as well as proliferation of PARP-1 deficient cells was inhibited by drug concentrations that were approximately 3-fold lower than their conventional counterparts. Treatment of cells with CHS 828 for 48 h did not induce apoptosis.
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PMID:Activation of p53 protein in normal and in tumor cells by a novel anticancer agent CHS 828. 1295 35

Sulforaphane (SFN), a constituent of cruciferous vegetables, is highly effective in affording protection against chemically induced cancers in animal models. Here, we report that SFN inhibited proliferation of cultured PC-3 human prostate cancer cells by inducing apoptosis that was characterized by appearance of cells with sub-G0/G1 DNA content, formation of cytoplasmic histone associated DNA fragments and cleavage of poly(ADP-ribose)polymerase (PARP). SFN-induced apoptosis was associated with up-regulation of Bax, down-regulation of Bcl-2 and activation of caspases-3, -9 and -8. SFN-induced apoptosis, and cleavage of procaspase-3 and PARP were blocked upon pre-treatment of cells with pan caspase inhibitor z-VADfmk, and specific inhibitors of caspase-9 (z-LEHDfmk) and caspase-8 (z-IETDfmk) suggesting involvement of both caspase-9 and caspase-8 pathways in SFN-induced cell death. Oral administration of SFN (5.6 micro mol, 3 times/week) significantly inhibited growth of PC-3 xenografts in nude mice. For instance, 10 days after starting therapy, the average tumor volumes in control and SFN-treated mice were 170 +/- 13 and 80 +/- 14 mm3, respectively, reflecting a >50% reduction in tumor volume due to SFN administration. To the best of our knowledge, the present study is the first published report to document in vivo anticancer activity of SFN in a tumor xenograft model.
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PMID:Sulforaphane induces caspase-mediated apoptosis in cultured PC-3 human prostate cancer cells and retards growth of PC-3 xenografts in vivo. 1451 58

Saikosaponins, the main active constituents of Bupleurum spp., have been shown to possess immunomodulatory, hepatoprotective, anti-tumor and anti-viral activities. In this study, saikosaponins a, c and d were evaluated for cytotoxicity and anti-hepatitis B virus ( HBV) activities. Results showed that, with the exception of saikosaponins a and d, HBV-transfected human hepatoma cells (2.2.15 cells) cultured with saikosaponin c showed a significantly lower level of HBeAg in culture medium. Saikosaponin c also possessed activity in inhibiting HBV DNA replication; this inhibitory effect was not due to the cytotoxicity of saikosaponin c or its effect on 2.2.15 cell proliferation. Although saikosaponin d exhibited cytotoxicity on 2.2.15 cells, it failed to inhibit HBV multiplication. The cytotoxicity of saikosaponin d against HepG2 human hepatocellular carcinoma cells was due to the induction of apoptosis through the activation of caspases 3 and 7, which subsequently resulted in poly-ADP-ribose-polymerase (PARP) cleavage. DNA fragmentation was clearly noted at more than 6 h after HepG2 cells exposure to saikosaponin d. The present study concludes that saikosaponin c exhibits anti-HBV activity and saikosaponin d possesses potent cytotoxicity against human hepatocellular carcinoma cells.
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PMID:Cytotoxicity and anti-hepatitis B virus activities of saikosaponins from Bupleurum species. 1453 Oct 19

Se-methylselenocysteine (Se-MSC) has been shown to possess potent chemopreventive and anti-tumor properties. However, its exact mechanism of action is still not well understood. The present study investigated the mechanism of Se-MSC on the induction of apoptosis using U937 human leukemia cells. Se-MSC induced dose- and time-dependent apoptosis of U937 cells as assessed by flow cytometry analysis, DNA fragmentation, and proteolytic cleavage of poly-(ADP-ribose) polymerase (PARP). Se-MSC increased time- and dose-dependent cytochrome c accumulation in the cytosol, which was greatly inhibited by overexpression of Bcl-2, suggesting that the apoptotic effect by Se-MSC in U937 cells is mitochondrial-dependent. Se-MSC also induced activation of caspases, followed by proteolytic cleavage of PKC-delta. The Se-MSC-induced apoptosis required activities of caspases since pretreatment of a pan-caspase inhibitor z-VAD-fmk greatly suppressed the Se-MSC-induced apoptosis as well as proteolytic cleavage of PKC-delta, suggesting activation of caspases is critical for the Se-MSC-induced apoptosis, and caspases lie upstream of PKC-delta. The Se-MSC-induced apoptosis of U937 cells also required activity of PKC-delta because pretreatment of rottlerin, a specific PKC-delta inhibitor greatly blocked the Se-MSC-induced apoptosis as well as processing and activities of caspases, suggesting activation of PKC-delta is also important for the Se-MSC-induced apoptosis of U937 cells, and PKC-delta lies upstream of caspases. Together, our data suggest the apoptotic mechanism by Se-MSC in U937 cells may be related to cytochrome c release from the mitochondria, and mutual activation between caspases and PKC-delta via a positive feedback mechanism, which may potentiate the apoptotic action by Se-MSC in U937 cells.
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PMID:Induction of apoptosis by Se-MSC in U937 human leukemia cells through release of cytochrome c and activation of caspases and PKC-delta: mutual regulation between caspases and PKC-delta via a positive feedback mechanism. 1453 2

This study aimed to examine the activation of poly(ADP-ribose) polymerase (PARP) and the accumulation of its end product, poly(ADP-ribose) (PAR), in uterine leiomyoma specimens obtained from 25 patients receiving Leuplin depot [leuprorelin acetate, depot (LA)] treatment and 46 control patients and explore their correlation with tumor shrinkage and degeneration caused by the therapy. Immunoblotting analysis showed that specimens from LA-treated patients had higher PARP expression. The numbers of both PARP- and PAR-immunolabeled cells were higher in leiomyoma with LA treatment. This was correlated with the clinical response of LA therapy that LA induced more leiomyoma degeneration. The analysis of power Doppler sonography indicated a progressive decrease in blood supply to tumor following LA treatment. In vitro experiments using primarily cultured leiomyoma cells exhibited that the deprivation of serum or ovarian hormones or LA directly failed to induce PARP and PAR production. Our results suggested that reduced blood flow and subsequent ischemic damages in leiomyoma could be responsible for PARP overexpression and PAR accumulation, clinical response, and tumor degeneration caused by LA treatment.
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PMID:Enhanced polyadenosine diphosphate-ribosylation in gonadotropin-releasing hormone agonist-treated uterine leiomyoma. 1455 88

Poly(ADP-ribose) metabolism plays a major role in DNA repair, transcription, replication, and recombination. Poly(ADP-ribose) polymerases are localized primarily to the nucleus, whereas significant levels of poly(ADP-ribose) glycohydrolase (PARG) are believed to be located in the cytoplasm. Only one PARG gene has been identified, but prior studies have reported multiple products of this gene. Here we studied PARG activity and PARG gene expression in several CNS cell types that span the cell growth spectrum: rapidly dividing C6 glioma tumor cells, dividing astrocytes, non-dividing astrocytes (due to contact inhibition), and post-mitotic neurons. Activity assays showed no overall differences between these cell types, but the nuclear to cytoplasmic ratio of PARG activity was highest in C6 glioma cells and lowest in neurons. Western blotting revealed full-length PARG as well as lower molecular weight PARG species in all four cell types.
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PMID:Expression and activity of poly(ADP-ribose) glycohydrolase in cultured astrocytes, neurons, and C6 glioma cells. 1455 56

Recently we have shown that galanin binding significantly correlates with survival in neuroblastoma patients, indicating a possible modulatory role of galanin receptors in neuroblastic tumor biology. However, the molecular mechanisms beyond this correlation have not been elucidated. Here, the cellular effects on activation of specific galanin receptor subtypes in human SH-SY5Y neuroblastoma cells were analyzed using a tetracycline-controlled expression system. Pharmacological studies confirmed the inducible expression of high affinity binding sites for galanin in SH-SY5Y cells transfected with the galanin receptors GalR1 (SY5Y/GalR1) and GalR2 (SY5Y/GalR2). Microphysiometry revealed that both receptor subtypes were able to mediate an intracellular signal upon galanin application. Interestingly, induction of receptor expression and treatment with 100 nm galanin resulted in a dramatic decrease in cell viability in SY5Y/GalR2 cells (93 +/- 3%) compared with a less pronounced effect in SY5Y/GalR1 cells (19 +/- 10%). The antiproliferative potency of galanin was 100-fold higher in SY5Y/GalR2 (50% effective concentration, 1.1 nm) than in SY5Y/GalR1 cells (50% effective concentration, 190 nm). Furthermore, activation of receptor expression and exposure to galanin resulted in apparent morphological changes indicative of apoptosis in SY5Y/GalR2 cells only. Induction of cell death by the apoptotic process was confirmed by poly-(ADP-ribose)-polymerase cleavage, caspase-3 activation, and the typical laddering of DNA. This study indicates that a high level of GalR2 expression is able to inhibit cell proliferation and induce apoptosis in neuroblastoma cells and therefore identifies GalR2 as a possible target for pharmacological intervention in neuroblastoma.
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PMID:Galanin receptor subtype GalR2 mediates apoptosis in SH-SY5Y neuroblastoma cells. 1459 62


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