Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.30 (PARP)
 13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Asbestos causes asbestosis and various malignancies by mechanisms that are not clearly defined. Here, we review the accumulating evidence showing that asbestos is directly genotoxic by inducing DNA strand breaks (DNA-SB) and apoptosis in relevant lung target cells. Although the exact mechanisms by which asbestos causes DNA damage and apoptosis are not firmly established, some of the implicated mechanisms include the generation of iron-derived reactive oxygen species (ROS) as well as reactive nitrogen species (RNS), alteration in the mitochondrial function, and activation of the death receptor pathway. We focus on the accumulating evidence implicating ROS. DNA repair mechanisms have a key role in limiting the extent of DNA damage. Recent studies show that asbestos activates DNA repair enzymes such as apurinic/apyrimidinic endonuclease (APE) and poly (ADP-ribose) polymerase (PARP). Asbestos-induced neoplastic transformation may result in the setting where DNA damage overwhelms DNA repair in the face of a persistent proliferative signal. Strategies aimed at limiting asbestos-induced oxidative stress may reduce DNA damage and, as such, prevent malignant transformation.
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PMID:Asbestos-induced pulmonary toxicity: role of DNA damage and apoptosis. 1277 95

Asbestos is known to induce malignant mesothelioma (MM) and other asbestos-related diseases. It is directly genotoxic by inducing DNA strand breaks and cytotoxic by promoting apoptosis in lung target cells. Poly(ADP-ribose) polymerase-1 (PARP1) is a nuclear zinc-finger protein with a function as a DNA damage sensor. To determine whether PARP1 is involved in asbestos-induced carcinogenesis, PARP1 expression and activity as well as DNA damage and repair were evaluated in circulating cells of asbestos-exposed subjects, MM patients and age-matched controls. PARP1 expression and activity were also evaluated in pleural biopsies of MM patients and compared with normal tissue. Accumulation of the pre-mutagenic 8-hydroxy-2'-deoxyguanosine and elevated PARP1 expression were found both in asbestos-exposed subjects and MM patients. Although PARP1 was highly expressed, its activity was relatively low. Low DNA repair efficiency was observed in lymphocytes from MM patients. High expression of PARP1 associated with low PARP activity was also found in MM biopsies. To mimic PARP1 dysfunction, PARP1 expression and activity were induced in immortalised mesothelial cells by their exposure to asbestos in the presence of a PARP1 inhibitor, which resulted in transformation of the cells. We propose that exposure to asbestos inhibits the PARP1 activity possibly resulting in higher DNA instability, thus causing malignant transformation.
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PMID:Asbestos exposure affects poly(ADP-ribose) polymerase-1 activity: role in asbestos-induced carcinogenesis. 2154 85

Malignant Pleural Mesothelioma (MMe) is a rare but increasingly prevalent, highly aggressive cancer with poor prognosis. The aetiology of MMe is essentially a function of previous exposure to asbestos fibres, which are considered to be an early-stage carcinogen. Asbestos is toxic to human mesothelial cells (HMCs), that activate the nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP1) to repair DNA. The targeting of PARP1 is showing considerable potential for delivering selective tumour cell kill while sparing normal cells, and offers a scientifically rational clinical application. We investigated PARP1 expression in normal mesothelial and MMe tissues samples. Immunohistochemical analysis revealed low PARP1 staining in peritumoural mesothelium. As opposite, a progressive increase in epithelioid and in the most aggressive sarcomatoid MMe tissues was evident. In MMe cell lines, we correlated increased PARP1 expression to sensitivity to its inhibitor CO-338 and demonstrated that CO-338 significantly reduced cell viability as single agent and was synergistic with cis-platin. Interestingly, we described a new correlation between PARP1 and the AKT/mTOR axis regulated by SIRT1. SIRT1 has a role in the modulation of AKT activation and PARP1 has been described to be a gatekeeper for SIRT1 activity by limiting NAD+ availability. Here, we firstly demonstrate an inverse correlation between AKT acetylation and phosphorylation modulated by SIRT1 in MMe cells treated with CO-338. In conclusion, this study demonstrates that PARP1 overexpression defines increased responsiveness to its inhibition, then these results imply that a substantial fraction of patients could be candidates for therapy with PARP inhibitors.
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PMID:PARP1 inhibition affects pleural mesothelioma cell viability and uncouples AKT/mTOR axis via SIRT1. 2330 73

Asbestos fibers have long been considered nongenotoxic because of the absence of point asbestos-treated cells mutations in several assays. More recently, some studies have demonstrated that various kinds of DNA damage were observed in asbestos-treated cells, namely, base hydroxylation, DNA adducts, and DNA breaks. The occurrence of DNA breakage has been mostly suggested by indirect methods. We investigated DNA damage produced by Rhodesian chrysotile fibers in a model of normal rat pleural mesothelial cells (RPMC) developed in our laboratory, by different approaches. DNA breakage and repair of DNA damage were evidenced by the enhancement of the activity of poly(ADP)ribose polymerase (PARP) and of unscheduled DNA synthesis, and were suggested by cell cycle arrest in asbestos-exposed RPMC. In growing cells, a cell cycle arrest was observed at the G1-S transition. DNA breakage was also demonstrated by the formation of comets in single-cell gel electrophoresis (SCGE) assay. The results showed that comets were generated by asbestos, as assessed by the significant increase in mean tail length and mean tail moment after exposure to asbestos. In RPMC-TSV40 (i.e., RPMC in which the protein was p53 inactivated by infection with a retroviral recombinant encoding the large T antigen of the SV40 virus), the comet parameters were moderately enhanced. Regarding previous results of an impairment of DNA repair in RPMC-TSV40, the SCGE results suggest that chrysotile caused DNA breakage in both RPMC and RPMC-TSV40. Moreover, these findings lead to the hypothesis that DNA repair was impaired in RPMC-TSV40.
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PMID:Investigations of DNA Damage Produced by Asbestos Fibers in Rat Pleural Mesothelial Cells. 2636 15