PJ34 hydrochloride

PJ34 is a novel and potent inhibitor of poly(ADP-ribose) polymerase (PARP), an enzyme involved in DNA repair and cell proliferation, that dose-dependently inhibits purified PARP enzyme in a cell-free assay with half maximal effective concentration EC₅₀ value of 20 nM. Unlike other PARP inhibitors (such as 3-AB), PJ34 does not possess any antioxidant properties but exhibits 10,000 times greater PARP inhibition than 3-AB (EC₅₀ = 200 μM). PJ34 has been found to have neuro-protective effects and enhance the chemotherapeutic effects in several tumor types. Study results have shown that PJ34 inhibits peroxynitrite-induced cell necrosis with EC₅₀ value of 20 nM and dose-dependently suppresses the growth of HepG2 cells.

Reference

Sheng-Hui Huang, Min Xiong, Xiao-Ping Chen, Zhen-Yu Xiao, Yin-Feng Zhao and Zhi-Yong Huang. PJ34, an inhibitor of PARP-1, suppresses cell growth and enhances the suppressive effects of cisplatin in liver cancer cells. Oncology Reports 20: 567-572, 2008

Galaleldin E. Abdelkarim, Karen Gertz, Christoph Harms, Juri Katchanov, Ulrich Dirnagl, Csaba Szabo and Matthias Enders. Protective effects of PJ34, a novel, potent inhibitor of poly(ADP-ribose) polymerase (PARP) in in vitro and in vivo models of stroke. International Journal of Molecular Medicine 7: 255-260, 2001

Temporal progression of PARP activity in the Prph2 mutant rd2 mouse: Neuroprotective effects of the PARP inhibitor PJ34.[Pubmed:28723922]

PLoS One. 2017 Jul 19;12(7):e0181374.

Peripherin (peripherin/rds) is a membrane-associated protein that plays a critical role in the morphogenesis of rod and cone photoreceptor outer segments. Mutations in the corresponding PRPH2 gene cause different types of retinal dystrophies characterized by a loss of photoreceptors. Over activation of poly-ADP-ribose polymerase (PARP) was previously shown to be involved in different animal models for hereditary retinal dystrophies. This includes the rd2 mouse, which suffers from a human homologous mutation in the PRPH2 gene. In the present study, we show that increased retinal PARP activity and poly-ADP-ribosylation of proteins occurs before the peak of rd2 photoreceptor degeneration. Inhibition of PARP activity with the well-characterized PARP inhibitor PJ34 decreased the levels of poly-ADP-ribosylation and photoreceptor cell death. These results suggest a causal involvement of PARP in photoreceptor degeneration caused by peripherin mutations and highlight the possibility to use PARP inhibition for the mutation-independent treatment of hereditary retinal dystrophies.

Cytotoxicity of anticancer drugs and PJ-34 (poly(ADP-ribose)polymerase-1 (PARP-1) inhibitor) on HL-60 and Jurkat cells.[Pubmed:28791810]

Adv Clin Exp Med. 2017 May-Jun;26(3):379-385.

BACKGROUND: The majority of the clinical trials with poly(ADP-ribose)polymerase-1 (PARP-1) inhibitors were conducted or are ongoing in patients with solid tumors, while trials with leukemia patients are less frequent. Surprisingly scarce data is available on the combinatory effects of PARP inhibitors with DNA damaging antitumor drugs in leukemic cells (primary cells or established lines). OBJECTIVES: The aim of the present study was to assess the effect of PJ-34 (PARP-1 inhibitor) on the cytotoxicity of different antileukemic drugs with different DNA damaging mechanisms and potency (doxorubicin, etoposide, cytarabine and chlorambucil) in human leukemic Jurkat and HL-60 cells. MATERIAL AND METHODS: Different exposure scenarios were applied: 1) 72 h simultaneous incubation with PJ-34 (2.5 or 5 muM for Jurkat and HL-60 cells, respectively) and a drug used at a wide concentration range; 2) preincubation of the cells with PJ-34 for 24 h and then with a combination of PJ-34 + drug for an additional 48 h; 3) preincubation of the cells with the drug for 24 h with a subsequent incubation with a combination of PJ-34 + drug for an additional 48 h. Cytotoxicity was assessed using a WST-1 reduction test. RESULTS: It was determined that PJ-34, when used in all 3 scenarios, did not induce any significant enhancement of cytotoxicity of the drugs either in Jurkat or in HL-60 cells. CONCLUSIONS: Although the results do not confirm the beneficial effects of PARP inhibition in combination treatment of the leukemic cells, we propose that future studies including an additional step with the inhibition of DNA repair by homologous recombination should provide promising results.

Poly(ADP-ribose) polymerase 1 contributes to oxidative stress through downregulation of sirtuin 3 during cisplatin nephrotoxicity.[Pubmed:27722009]

Anat Cell Biol. 2016 Sep;49(3):165-176.

Enhanced oxidative stress is a hallmark of cisplatin nephrotoxicity, and inhibition of poly(ADP-ribose) polymerase 1 (PARP1) attenuates oxidative stress during cisplatin nephrotoxicity; however, the precise mechanisms behind its action remain elusive. Here, using an in vitro model of cisplatin-induced injury to human kidney proximal tubular cells, we demonstrated that the protective effect of PARP1 inhibition on oxidative stress is associated with sirtuin 3 (SIRT3) activation. Exposure to 400 microM cisplatin for 8 hours in cells decreased activity and expression of manganese superoxide dismutase (MnSOD), catalase, glutathione peroxidase (GPX), and SIRT3, while it increased their lysine acetylation. However, treatment with 1 microM PJ34 hydrochloride, a potent PARP1 inhibitor, restored activity and/or expression in those antioxidant enzymes, decreased lysine acetylation of those enzymes, and improved SIRT3 expression and activity in the cisplatin-injured cells. Using transfection with SIRT3 double nickase plasmids, SIRT3-deficient cells given cisplatin did not show the ameliorable effect of PARP1 inhibition on lysine acetylation and activity of antioxidant enzymes, including MnSOD, catalase and GPX. Furthermore, SIRT3 deficiency in cisplatin-injured cells prevented PARP1 inhibition-induced increase in forkhead box O3a transcriptional activity, and upregulation of MnSOD and catalase. Finally, loss of SIRT3 in cisplatin-exposed cells removed the protective effect of PARP1 inhibition against oxidative stress, represented by the concentration of lipid hydroperoxide and 8-hydroxy-2'-deoxyguanosine; and necrotic cell death represented by a percentage of propidium iodide-positively stained cells. Taken together, these results indicate that PARP1 inhibition protects kidney proximal tubular cells against oxidative stress through SIRT3 activation during cisplatin nephrotoxicity.

Structural Basis for Potency and Promiscuity in Poly(ADP-ribose) Polymerase (PARP) and Tankyrase Inhibitors.[Pubmed:28001384]

J Med Chem. 2017 Feb 23;60(4):1262-1271.

Selective inhibitors could help unveil the mechanisms by which inhibition of poly(ADP-ribose) polymerases (PARPs) elicits clinical benefits in cancer therapy. We profiled 10 clinical PARP inhibitors and commonly used research tools for their inhibition of multiple PARP enzymes. We also determined crystal structures of these compounds bound to PARP1 or PARP2. Veliparib and niraparib are selective inhibitors of PARP1 and PARP2; olaparib, rucaparib, and talazoparib are more potent inhibitors of PARP1 but are less selective. PJ34 and UPF1069 are broad PARP inhibitors; PJ34 inserts a flexible moiety into hydrophobic subpockets in various ADP-ribosyltransferases. XAV939 is a promiscuous tankyrase inhibitor and a potent inhibitor of PARP1 in vitro and in cells, whereas IWR1 and AZ-6102 are tankyrase selective. Our biochemical and structural analysis of PARP inhibitor potencies establishes a molecular basis for either selectivity or promiscuity and provides a benchmark for experimental design in assessment of PARP inhibitor effects.

Effects of PARP-1 inhibitor and ERK inhibitor on epithelial mesenchymal transitions of the ovarian cancer SKOV3 cells.[Pubmed:27668317]

Pharmacol Rep. 2016 Dec;68(6):1225-1229.

BACKGROUND: To assess the effects of the poly (ADP-ribose) polymerase-1 (PARP-1) inhibitor PJ34 and ERK1/2 inhibitor U0126 on the proliferation and epithelial mesenchymal transitions (EMT) of cisplatin resistant ovarian cancer SKOV-3 cells. METHODS: Proliferation of SKOV-3 cells was evaluated using a 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium bromide assay with PJ34 and U0126 treatment. Expression changes of E-cadherin and vimentin with PJ34 and U0126 treatment was examined using Western blot and quantitative PCR. In addition, invasion assay was performed in cells treated with PJ34 and U0126. RESULTS: PJ34 and U0126 inhibited proliferation of SKOV-3 cells in a time dependent manner. PJ34 and U0126 suppressed the expression of vimentin and enhanced the expression of E-cadherin. PJ34 and U0126 reduced cell invasion. The inhibitory effects of PJ34 and U0126 were stronger than PJ34 alone. PJ34 inhibited the proliferation and invasion of SKOV-3 cells which can be enhanced by ERK1/2 inhibitor U0126. CONCLUSIONS: These inhibitory effects are partially due to PARP-1 and ERK1/2 mediated attenuation of EMT activity.

Identification of pim kinases as novel targets for PJ34 with confounding effects in PARP biology.[Pubmed:23025350]

ACS Chem Biol. 2012 Dec 21;7(12):1962-7.

Small molecules are widely used in chemical biology without complete knowledge of their target profile, at risk of deriving conclusions that ignore potential confounding effects from unknown off-target interactions. The prediction and further experimental confirmation of novel affinities for PJ34 on Pim1 (IC(50) = 3.7 muM) and Pim2 (IC(50) = 16 muM) serine/threonine kinases, together with their involvement in many of the processes relevant to PARP biology, questions the appropriateness of using PJ34 as a chemical tool to probe the biological role of PARP1 and PARP2 at the high micromolar concentrations applied in most studies.

Poly(ADP-ribose) polymerase 1 activation is required for cisplatin nephrotoxicity.[Pubmed:22437413]

Kidney Int. 2012 Jul;82(2):193-203.

Apoptosis, necrosis, and inflammation are hallmarks of cisplatin nephrotoxicity; however, the role and mechanisms of necrosis and inflammation remains undefined. As poly(ADP-ribose) polymerase 1 (PARP1) inhibition or its gene deletion is renoprotective in several renal disease models, we tested whether its activation may be involved in cisplatin nephrotoxicity. Parp1 deficiency was found to reduce cisplatin-induced kidney dysfunction, oxidative stress, and tubular necrosis, but not apoptosis. Moreover, neutrophil infiltration, activation of nuclear factor-kappaB, c-Jun N-terminal kinases, p38 mitogen-activated protein kinase, and upregulation of proinflammatory genes were all abrogated by Parp1 deficiency. Using proximal tubule epithelial cells isolated from Parp1-deficient and wild-type mice and pharmacological inhibitors, we found evidence for a PARP1/Toll-like receptor 4/p38/tumor necrosis factor-alpha axis following cisplatin injury. Furthermore, pharmacological inhibition of PARP1 protected against cisplatin-induced kidney structural/functional damage and inflammation. Thus, our findings suggest that PARP1 activation is a primary signal and its inhibition/loss protects against cisplatin-induced nephrotoxicity. Targeting PARP1 may offer a potential therapeutic strategy for cisplatin nephrotoxicity.

Poly(ADPR)polymerase inhibition and apoptosis induction in cDDP-treated human carcinoma cell lines.[Pubmed:18468580]

Biochem Pharmacol. 2008 Jun 15;75(12):2356-63.

Poly(ADPR)polymerases' (PARPs) inhibitors potentiate the cytotoxic effects of chemotherapeutic agents like alkylating compounds and TOPO I poisons, while their action in combination with cisplatin still needs investigation. In fact, one of the earliest responses to DNA single- or double-strand breaks is the synthesis of poly(ADP-ribose) (PAR) by PARPs; these enzymes are components of DNA repair machineries and substrates of caspases. Cisplatin (cDDP) yields intra- and inter-strand DNA cross-links and several proteins that recognise cDDP-induced DNA damage, such as p53, are also targets of poly(ADP-ribosyl)ation. We compared the effects of treatments with cDDP and the PARPs inhibitor PJ34 in p53 mutated carcinoma cell lines (HeLa, KB, HT29) that exhibited differential sensitivities to the drugs, in terms of cell growth inhibition and onset of apoptosis. In cDDP-resistant HT29 cells we determined: (i) PJ34 potentiation of cDDP-induced cell growth inhibition; (ii) an increment of PARP-1 automodification following cDDP treatment. In cDDP-sensitive HeLa cells, we found that the drug induced apoptotic cell death associated with caspase-dependent PARP-1 proteolysis.

Protective effects of PJ34, a novel, potent inhibitor of poly(ADP-ribose) polymerase (PARP) in in vitro and in vivo models of stroke.[Pubmed:11179503]

Int J Mol Med. 2001 Mar;7(3):255-60.

Focal cerebral ischemia activates the nuclear protein poly(ADP-ribose) polymerase (PARP) by single DNA strand breaks which leads to energy depletion and cell necrosis. Deletion or inhibition of PARP protects against ischemic brain injury. Here we examined the neuroprotective effect of PJ34, a novel potent inhibitor of PARP in vitro and in vivo. Serum-free primary neuronal cultures derived from rat cortex (E15-17) and kept in culture for 10 days were exposed to oxygen glucose deprivation (OGD) in vitro. Neuronal injury was quantified by LDH release after 24 h. Pretreatment with 30-1000 nM PJ34 significantly protected from OGD-induced cell injury in a dose-dependent manner. For in vivo experiments SV/129 mice were treated with PJ34 (50 microg) by intraperitoneal injection 2 h before 1 h middle cerebral artery occlusion (MCAo) and again 6 h later. Twenty-three h after reperfusion ischemic injury was significantly decreased compared to vehicle-treated controls (infarct volume reduction of 40%, p<0.05). Similarly, in a rat model of MCAo (2 h occlusion followed by up to 22 h reperfusion), PJ34 administration (10 mg/kg i.v.) significantly reduced infarct size, and the effect of the drug was maintained even if it was given as late as 10 min prior to reperfusion time. PJ34 significantly protected in a 4 h, but not in a 24 h permanent occlusion model. In conclusion, PJ34, a novel, potent inhibitor of PARP exerts massive neuroprotective agents, with a significant therapeutic window of opportunity. The present work strengthens the concept that pharmacological PARP inhibition may be a suitable approach for the treatment of acute stroke in man.