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)

Infection with vesicular stomatitis virus (VSV), a rhabdovirus and economically significant animal pathogen, was previously demonstrated to induce apoptosis. The mechanism of induction and the role of apoptosis in the VSV-host response have not been completely elucidated. Previous data from our laboratory have suggested that caspase-3 is required for the induction of apoptosis but not viral replication in VSV-infected cells. However, these studies used inhibitors that are selective but not specific for caspase-3. To circumvent this difficulty, we infected both MCF-7 cells which do not express caspases-3 (null), and stable transfectants which express caspase-3 (C3+). When caspase-3 null cells were infected, significant PARP cleavage did not occur, but when C3+ cells were infected, PARP cleavage did occur efficiently. Studies in null and C3+ also suggest that: (1) caspases-3 and -7 are activated sequentially after VSV infection; (2) cell shrinkage and detachment are caspase-3 dependent, but cell rounding is not; and (3) the viral titers were similar between caspase-3 null and C3+ cells suggesting that activation of caspases-3 and -7 are not required for viral replication. Taken together, these results strongly support that the activation of caspase-3 by VSV infection is required for efficient apoptosis induction but not viral replication in vitro. Apoptosis mediated by caspase-3, then, is likely either a host cell response to viral replication or perhaps may be required for in vivo viral replication and spread.
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PMID:Requirement of caspase-3 for efficient apoptosis induction and caspase-7 activation but not viral replication or cell rounding in cells infected with vesicular stomatitis virus. 1250 17

NuMA is a nuclear matrix protein that has an essential function in the organization of the mitotic spindle. Here we have studied the fate of NuMA in Fas-treated apoptotic Jurkat T and HeLa cells. We show that in both cell lines NuMA is an early target protein for caspases and that NuMA is cleaved coincidently with poly(ADP-ribose) polymerase-1 (PARP-1) and nuclear lamin B. NuMA is cleaved differently in Jurkat T and HeLa cells, suggesting that different sets of caspases are activated in these cell lines. The normal diffuse intranuclear distribution of NuMA changed during apoptosis: first NuMA condensed, then concentrated in the center of the nucleus and finally encircled the nuclear fragments within the apoptotic bodies. NuMA seems to be preferentially cleaved by caspase-3 in vivo since it was not cleaved in staurosporine-treated caspase-3-null MCF-7 breast cancer cells. The cleavage of NuMA, lamin B and PARP-1 was inhibited in the presence of three different caspase inhibitors: z-DEVD-FMK, z-VEID-FMK and z-IETD-FMK. Furthermore, in the presence of caspase inhibitors approximately 5-10% of the cells showed atypical apoptotic morphology. These cells had convoluted nuclei, altered chromatin structure and additionally, they were negative for NuMA and lamins. Since caspase-8, -3 and -7 were not activated and PARP was not cleaved in these cells as judged by western blotting and immunofluorescence studies, it is likely that this is an atypical form of programmed cell death owing to a proteinase(s) independent of caspases. These results characterize the role of NuMA in programmed cell death and suggest that cleavage of NuMA plays a role in apoptotic nuclear breakdown.
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PMID:NuMA and nuclear lamins behave differently in Fas-mediated apoptosis. 1250 17

Poly(ADP-ribose) polymerase-1 (PARP-1) and the p53 tumor suppressor protein are both involved in the cellular response to genotoxic stress. Upon binding to the site of DNA strand breakage, PARP-1 is activated, leading to rapid and transient poly(ADP-ribosyl)ation of nuclear proteins using NAD+ as substrate. To investigate the role of PARP-1 in the p53 response to ionizing radiation in human cells, PARP-1 function was disrupted in wild-type p53 expressing MCF-7 and BJ/TERT cells using two strategies: chemical inhibition with 1,5-dihydroxyisoquinoline, and trans-dominant inhibition by overexpression of the PARP-1 DNA-binding domain. Although a number of proteins can catalyze poly(ADP-ribosyl)ation in addition to PARP-1, we show that PARP-1 is the only detectable active species in BJ/TERT and MCF-7 cells. 1,5-Dihydroxyisoquinoline treatment prior to ionizing radiation delayed and attenuated the induction of two p53-responsive genes, p21 and mdm-2, and led to suppression of the p53-mediated G1-arrest response in MCF-7 and BJ/TERT cells. Trans-dominant inhibition of PARP-1 by overexpression of the PARP-1 DNA-binding domain in MCF-7 cells also led to a delay and attenuation in p21 induction and suppression of the p53-mediated G1 arrest response to ionizing radiation. Hence, inhibition of endogenous PARP-1 function suppresses the transactivation function of p53 in response to ionizing radiation. This study establishes PARP-1 as a critical regulator of the p53 response to DNA damage.
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PMID:Poly(ADP-ribose) polymerase-1 is a positive regulator of the p53-mediated G1 arrest response following ionizing radiation. 1264 83

In estrogen receptor (ER) positive breast cancer cells such as MCF-7 cells, the anti-tumor effects of 1,25(OH)(2)D(3) (1,25D(3)) may be secondary to disruption of estrogen mediated survival signals. If so, then sensitivity to 1,25D(3) mediated growth arrest could be reduced in estrogen independent breast cancer cells. The aim of these studies was to determine the effects of 1,25D(3) and EB1089 on the ER negative, invasive human breast cancer cell line SUM-159PT. 1,25D(3) and EB1089 reduced SUM-159PT cell growth subsequent to elevation of p27 and p21 levels. 1,25D(3) mediated apoptosis of SUM-159PT cells was associated with an enrichment of membrane bound bax, a redistribution of cytochome c from the mitochondria to the cytosol and PARP cleavage. 1,25D(3) and EB1089 also inhibited SUM-159PT cell invasion through an 8 microM Matrigel membrane. In pre-clinical studies, EB1089 dramatically reduced the growth of SUM-159PT xenografts in nude mice. The decreased size of tumors from EB1089 treated mice was associated with decreased proliferation and increased DNA fragmentation. Our data support the concept that Vitamin D(3) compounds trigger apoptosis by mechanisms independent of estrogen signaling. These studies indicate that Vitamin D(3) based therapeutics may be beneficial, alone or in conjunction with other agents, for the treatment of estrogen independent breast cancer.
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PMID:Efficacy of Vitamin D compounds to modulate estrogen receptor negative breast cancer growth and invasion. 1271 Oct 2

Beta-lapachone (beta-Lap) triggers apoptosis in a number of human breast and prostate cancer cell lines through a unique apoptotic pathway that is dependent upon NQO1, a two-electron reductase. Recently, our laboratory showed that beta-lap-exposed MCF-7 cells exhibited an early increase in intracellular cytosolic Ca(2+) from endoplasmic reticulum stores, and that BAPTA-AM (an intracellular Ca(2+) chelator) blocked these early increases and partially inhibited all aspects of beta-lap-induced apoptosis. We now show that exposure of NQO1-expressing breast cancer cells to beta-lap stimulates a unique proteolytic apoptotic pathway involving mu-calpain activation. No apparent activation of m-calpain was noted. Upon activation, mu-calpain translocated to the nucleus concomitant with specific nuclear proteolytic events. Apoptotic responses in beta-lap-exposed NQO1-expressing cells were significantly delayed and survival enhanced by exogenous over-expression of calpastatin, a natural inhibitor of mu- and m-calpains. Furthermore, purified mu-calpain cleaved PARP to a unique fragment (approximately 60 kDa), not previously reported for calpains. We provide evidence that beta-lap-induced, mu-calpain-stimulated apoptosis does not involve any known apoptotic caspases; the activated fragments of caspases were not observed after beta-lap exposures, nor were there any changes in the pro-enzyme forms as measured by Western blot analyses. The ability of beta-lap to trigger an apparently novel, p53-independent, calpain-mediated apoptotic cell death further support the development of this drug for improved breast cancer therapy.
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PMID:Mu-calpain activation in beta-lapachone-mediated apoptosis. 1275 May 53

The aim of our study was to explore the antiproliferative and pro-apoptotic action of roscovitine (ROSC) on human breast cancer MCF-7 cells. We examined the effect of ROSC on cell proliferation, cell cycle progression, nucleolar morphology, posttranslational modifications of histones as well as on induction of apoptosis. The effects of ROSC on the argyrophilic nucleolar organizer regions (AgNORs) and nucleolar RNA of MCF-7 cells were marked: ROSC treatment changed the pattern of AgNORs in a time-dependent manner. The disintegration of nucleoli manifested by increasing number of nucleolar fragments already began at 6 hr posttreatment. This was accompanied by a redistribution of the nucleolin from the nucleolus beginning after 6 hr and preceded a decrease of histone acetylation and phosphorylation. Inhibition of DNA synthesis and accumulation of G(2)/M-arrested cells starting 6 hr posttreatment coincided with a strong increase of the p53 level and with an appearance of a few cells committed to undergo apoptosis. However, all these changes preceded the main wave of apoptosis, which occurred after 24 hr ROSC treatment as assessed by determination of the frequency of Annexin binding, activation of caspases as well as of DNA fragmentation. Onset of PARP-1 cleavage detected by immunoblotting and by immunohistochemistry 6 hr or 9 hr posttreatment, respectively, preceded for a few hours the DNA fragmentation detected in situ by TUNEL assay. Reconstitution of MCF-7 cells with caspase-3 did not change the kinetics of ROSC-induced apoptosis. Our results show that disintegration of nucleoli is an early marker of ROSC-induced changes. Cell cycle arrest precedes the main wave of apoptosis.
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PMID:Rapid onset of nucleolar disintegration preceding cell cycle arrest in roscovitine-induced apoptosis of human MCF-7 breast cancer cells. 1284 42

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

The importance of the mitochondria in UV-induced apoptosis has become increasingly apparent. Following DNA damage cytochrome c and other pro-apoptotic factors are released from the mitochondria, allowing for formation of the apoptosome and subsequent cleavage and activation of caspase-9. Active caspase-9 then activates downstream caspases-3 and/or -7, which in turn cleave poly(ADP)-ribose polymerase (PARP) and other down-stream targets, resulting in apoptosis. In an effort to understand the mechanisms of Akt-mediated cell survival in breast cancer, we studied the effects of insulin-like growth factor (IGF)-I treatment on UV-treated MCF-7 human breast cancer cells. Apoptosis was induced in MCF-7 cells after UV treatment, as measured by caspase-7 and PARP cleavage, and IGF-I co-treatment protected against this response. Surprisingly caspase-9 cleavage was unchanged with UV and/or IGF-I treatment. Using MCF-7 cells overexpressing caspase-3 we have shown that resistance of caspase-9 to cleavage was not altered by the expression of caspase-3. Furthermore, overexpression of caspase-9 did not enhance PARP or caspase-7 cleavage after UV treatment. Because caspase-8 was activated with UV treatment alone, we believe that UV-induced apoptosis in MCF-7 cells occurs independently of cytochrome c and caspase-9, supporting the existence of a cytoplasmic inhibitor of cytochrome c in MCF-7 cells. We anticipate that such inhibitors may be overexpressed in cancer cells, allowing for treatment resistance.
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PMID:UV-induced apoptosis is mediated independent of caspase-9 in MCF-7 cells: a model for cytochrome c resistance. 1295 16

The poly(ADP-ribose) polymerase (PARP) family of nuclear enzymes is involved in the detection and signaling of single strand breaks induced either directly by ionizing radiation or indirectly by the sequential action of various DNA repair proteins. Therefore, PARP plays an important role in maintaining genome stability. Because PARP proteins contain two zinc finger motifs, these enzymes can be targets for reactive nitrogen oxide intermediates (RNOS) generated as a result of nitric oxide (NO) biosynthesis in an aerobic environment. The effects of RNOS on the activity of purified PARP were examined using donor compounds. Both NO and nitroxyl (HNO) donors were found to be inhibitory in a similar time and concentration manner, indicating that PARP activity can be modified under both nitrosative and oxidative conditions. Moreover, these RNOS donors elicited comparable PARP inhibition in Sf21 insect cell extract and intact human MCF-7 cancer cells. The concentrations of donor required for 90% inhibition of PARP activity produce RNOS at a similar magnitude to those generated in the cellular microenvironment of activated leukocytes, suggesting that cellular scavenging of RNOS may not be protective against PARP modification and that inhibition of PARP may be significant under inflammatory conditions.
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PMID:Inhibition of poly(ADP-RIBOSE) polymerase (PARP) by nitric oxide and reactive nitrogen oxide species. 1464 90

Drug resistance is a major impediment to the successful treatment of breast cancer using chemotherapy. The photoactivatable drug calphostin C has shown promise in killing select drug-resistant tumor cells lines in vitro. To assess the effectiveness of this agent in killing doxorubicin- or paclitaxel-resistant breast tumor cells and to explore its mode of action, MCF-7 cells were exposed to increasing concentrations of either doxorubicin or paclitaxel until maximum resistance was obtained. This resulted in the creation of isogenic drug-resistant MCF-7TAX and MCF-7DOX cell lines, which were approximately 50- and 65-fold resistant to paclitaxel and doxorubicin, respectively. Interestingly, calphostin C was able to kill MCF-7TAX cells as efficiently as wildtype MCF-7 cells (IC50s were 9.2 and 13.2 nM, respectively), while MCF-7DOX cells required a 5-fold higher concentration of calphostin C to achieve the same killing (IC50 = 64.2 nM). Consistent with their known mechanisms of action, paclitaxel killed tumor cells by inducing mitotic arrest and cell multinucleation, while doxorubicin induced plasma membrane blebbing and decreased nuclear staining with propidium iodide. In contrast, cytoplasmic vacuolization accompanied cell killing by calphostin C in these cell lines, without the induction of caspase-8 or PARP cleavage or the release of cytochrome c from mitochondria. Calphostin C had little effect on the uptake of either paclitaxel or doxorubicin by the cells. Taken together, the above data suggests that calphostin C is able to potently kill drug-resistant breast tumor cells through a mechanism that may involve the induction of cytoplasmic vacuolization, without activation of typical apoptotic pathways. Consequently, calphostin C may prove useful clinically to combat tumor growth in breast cancer patients whose tumors have become unresponsive to anthracyclines or taxanes, particularly in association with photodynamic therapy.
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PMID:Potent killing of paclitaxel- and doxorubicin-resistant breast cancer cells by calphostin C accompanied by cytoplasmic vacuolization. 1469 56


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