Synthesis of isoquinolinone-based tetracycles as poly (ADP-ribose) polymerase-1 (PARP-1) inhibitors

The isoquinolinone-based tetracyclic compounds were designed and synthesized and their PARP-1 inhibitory activity was evaluated. Most of synthesized compounds showed fairly good activity. Also the most active compound 6 showed its activity on potentiation of anticancer agents, temozolamide and etoposide, by 1.7 times, respectively.     

Poly(ADP-ribose) polymerase-1 (PARP-1) gene deficiency alleviates diabetic kidney disease

Poly(ADP-ribose)polymerase (PARP) inhibitors prevent or alleviate diabetic nephropathy. This study evaluated the role for PARP-1 in diabetic kidney disease using the PARP-1-deficient mouse. PARP-1?/? and the wild-type (129S1/SvImJ) mice were made diabetic with streptozotocin, and were maintained for 12 weeks. Final blood glucose concentrations were increased ～ 3.7-fold in both diabetic groups. PARP-1 protein expression (Western blot analysis) in the renal cortex was similar in non-diabetic and diabetic wild-type mice (100% and 107%) whereas all knockouts were PARP-1-negative. PARP-1 gene deficiency reduced urinary albumin (ELISA) and protein excretion prevented diabetes-induced kidney hypertrophy, and decreased mesangial expansion and collagen deposition (both assessed by histochemistry) as well as fibronectin expression. Renal podocyte loss (immunohistochemistry) and nitrotyrosine and transforming growth factor-β₁ accumulations (both by ELISA) were slightly lower in diabetic PARP-1?/? mice, but the differences with diabetic wild-type group did not achieve statistical significance. In conclusion, PARP-1?/? gene deficiency alleviates although does not completely prevent diabetic kidney disease.     

Substituted uracil derivatives as potent inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1)

A new class of PARP-1 inhibitors, namely substituted fused uracil derivatives were synthesised. Starting from a derivative with an IC(50)=2microM the chemical optimisation program led to compounds with more than a 100-fold increase in potency (IC(50)<20nM). Additionally, physicochemical and pharmacokinetic properties were evaluated. It could be shown that compounds bearing a piperazine or phenyl substituted betaAla-Gly side chain exhibited the best overall profile.     

Synthesis of isoquinolinone-based tricycles as novel poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors

The isoquinolinone-based tricyclic compounds were designed and synthesized. Preliminary biological study of these compounds provided potent compounds 17a, 33b, 33c, 33d, and 33g with low nanomolar IC₅₀s against PARP-1 enzyme.     

Synthesis and SAR of novel tricyclic quinoxalinone inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1)

Based on screening hit 1, a series of tricyclic quinoxalinones have been designed and evaluated for inhibition of PARP-1. Substitutions at the 7- and 8-positions of the quinoxalinone ring led to a number of compounds with good enzymatic and cellular potency. The tricyclic quinoxalinone class is sensitive to modifications of both the amine substituent and the tricyclic core. The synthesis and structure–activity relationship studies are presented.     

Poly(ADP-ribose) polymerase-2 (PARP-2) is required for efficient base excision DNA repair in association with PARP-1 and XRCC1

The DNA damage dependence of poly(ADP-ribose) polymerase-2 (PARP-2) activity is suggestive of its implication in genome surveillance and protection. Here we show that the PARP-2 gene, mainly expressed in actively dividing tissues follows, but to a smaller extent, that of PARP-1 during mouse development. We found that PARP-2 and PARP-1 homo- and heterodimerize; the interacting interfaces, sites of reciprocal modification, have been mapped. PARP-2 was also found to interact with three other proteins involved in the base excision repair pathway: x-ray cross complementing factor 1 (XRCC1), DNA polymerase beta, and DNA ligase III, already known as partners of PARP-1. XRCC1 negatively regulates PARP-2 activity, as it does for PARP-1, while being a polymer acceptor for both PARP-1 and PARP-2. To gain insight into the physiological role of PARP-2 in response to genotoxic stress, we developed by gene disruption mice deficient in PARP-2. Following treatment by the alkylating agent N-nitroso-N-methylurea (MNU), PARP-2-deficient cells displayed an important delay in DNA strand breaks resealing, similar to that observed in PARP-1 deficient cells, thus confirming that PARP-2 is also an active player in base excision repair despite its low capacity to synthesize ADP-ribose polymers.     

Poly(ADP-ribose) polymerase-1 (PARP-1) controls lung cell proliferation and repair after hyperoxia-induced lung damage

Oxygen-based therapies expose lung to elevated levels of ROS and induce lung cell damage and inflammation. Injured cells are replaced through increased proliferation and differentiation of epithelial cells and fibroblasts. Failure to modulate these processes leads to excessive cell proliferation, collagen deposition, fibrosis, and chronic lung disease. Poly(ADP-ribose) polymerase-1 (PARP-1) is activated in response to DNA damage and participates in DNA repair, genomic integrity, and cell death. In this study, we evaluated the role of PARP-1 in lung repair during recovery after acute hyperoxia exposure. We exposed PARP-1 -/- and wild-type mice for 64 h to 100% hyperoxia and let them recover in air for 5-21 days. PARP-1-deficient mice exhibited significantly higher lung cell hyperplasia and proliferation than PARP-1 +/+ animals after 5 and 10 days of recovery. This was accompanied by an increased inflammatory response in PARP-1 -/- compared with wild-type animals, characterized by neutrophil infiltration and increased IL-6 levels in bronchoalveolar lavages. These lesions were reversible, since the extent of the hyperplastic regions was reduced after 21 days of recovery and did not result in fibrosis. In vitro, lung primary fibroblasts derived from PARP-1 -/- mice showed a higher proliferative response than PARP-1 +/+ cells during air recovery after hyperoxia-induced growth arrest. Altogether, these results reveal an essential role of PARP-1 in the control of cell repair and tissue remodeling after hyperoxia-induced lung injury.     

Poly(ADP-ribose) polymerase-1 (PARP-1) pharmacogenetics, activity and expression analysis in cancer patients and healthy volunteers

There is a wide inter-individual variation in PARP-1 {PAR [poly(ADP-ribose)] polymerase 1} activity, which may have implications for health. We investigated if the variation: (i) is due to polymorphisms in the PARP-1 gene or PARP-1 protein expression; and (ii) affects patients' response to anticancer treatment. We studied 56 HV (healthy volunteers) and 118 CP (cancer patients) with supporting in vivo experiments. PARP activity ranged between 10 and 2600 pmol of PAR/106 cells and expression between 0.02-1.55 ng of PARP-1/μg of protein. PARP-1 expression correlated with activity in HV (R2=0.19, P=0.003) and CP (R2=0.06, P=0.01). A short CA repeat in the promoter was significantly associated with increased cancer risk [OR (odds ratio), 5.22; 95% CI (confidence interval), 1.79-15.24]. PARP activity was higher in men than women (P=0.04) in the HV. Male mice also had higher PARP activity than females or castrated males. Oestrogen supplementation activated PARP in PBMCs (peripheral blood mononuclear cells) from female mice (P=0.003), but inhibited PARP-1 in their livers by 80%. PARP activity and expression were not dependent on the investigated polymorphisms, but there was a modest correlation of PARP activity with expression. Studies in the HV revealed sex differences in PARP activity, which was confirmed in mice and shown to be associated with sex hormones. Toxic response to treatment was not associated with PARP activity and/or expression.     

Discovery and SAR of novel,potent and selective hexahydrobenzonaphthyridinone inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1)

A novel hexahydrobenzonaphthyridinone PARP-1 pharmacophore is reported, subsequent SAR exploration around this scaffold led to selective PARP-1 inhibitors with low nanomolar enzyme potency, displaying good cellular activity and promising rat PK properties.     

Synthesis and evaluation of tricyclic derivatives containing a non-aromatic amide as inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1)

Highly potent poly(ADP-ribose)polymerase-1 (PARP-1) inhibitors, including 9-hydroxy-1,2-dihydro-4H-thiopyrano[3,4-c]quinolin-5(6H)-one derivatives with a non-aromatic A-ring, were synthesized. Among the derivatives, 12a showed low nanomolar enzyme and cellular activity (IC₅₀ = 42 nM, ED₅₀ = 220 nM) with good water solubility. Further, 12a exhibited microsomal stability in vitro and brain permeability in vivo.     

Design and synthesis of poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors. Part 4: biological evaluation of imidazobenzodiazepines as potent PARP-1 inhibitors for treatment of ischemic injuries

A class of poly(ADP-ribose) polymerase (PARP-1) inhibitors, the imidazobenzodiazepines, are presented in this text. Several derivatives were designed and synthesized with ionizable groups (i.e., tertiary amines) in order to promote the desired pharmaceutical characteristics for administration in ischemic injury. Within this series, several compounds have excellent in vitro potency and our computational models accurately justify the structure-activity relationships (SARs) and highlight essential hydrogen bonding residues and hydrophobic pockets within the catalytic domain of PARP-1. Administration of these compounds (5q, 17a and 17e) in the mouse model of streptozotocin-induced diabetes results in maintainance of glucose levels. Furthermore, one such inhibitor (5g, IC(50)=26 nM) demonstrated significant reduction of infarct volume in the rat model of permanent focal cerebral ischemia.     

Synthesis, [18F] radiolabeling,and evaluation of poly (ADP-ribose) polymerase-1 (PARP-1) inhibitors for in vivo imaging of PARP-1 using positron emission tomography

Imaging of poly (ADP-ribose) polymerase-1 (PARP-1) expression in vivo is a potentially powerful tool for developing PARP-1 inhibitors for drug discovery and patient care. We have synthesized several derivatives of benzimidazole carboxamide as PARP-1 inhibitors, which can be ¹⁸F-labeled easily for positron emission tomographic (PET) imaging. Of the compounds synthesized, 12 had the highest inhibition potency for PARP-1 (IC₅₀ = 6.3 nM). [¹⁸F]12 was synthesized under conventional conditions in high specific activity with 40–50% decay-corrected yield. MicroPET studies using [¹⁸F]12 in MDA-MB-436 tumor-bearing mice demonstrated accumulation of [¹⁸F]12 in the tumor that was blocked by olaparib, suggesting that the uptake of [¹⁸F]12 in the tumor is specific to PARP-1 expression.     

Synthesis and structure-activity relationships of novel pyrrolocarbazole lactam analogs as potent and cell-permeable inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1)

A series of novel pyrrolocarbazole lactams was identified as potent PARP-1 inhibitors in vitro and in a PC12 cellular NAD(+) depletion assay. The SAR trends of substituents at the 3-position, as well as the effect of blocking the indole or lactam NH-groups of the template by methylation or formylation, are discussed in relation to molecular modeling studies.     

Down-modulation of poly(ADP-ribose) polymerase-1 (PARP-1) in human TUR leukemia cells restores transcriptional responsiveness for differentiation and cell cycle arrest

Aggressive tumor developing human TUR myeloid leukemia cells continued cell cycle progression in the presence of the differentiation-inducing phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Similar results were obtained after stable transfection of TUR cells with the pTracer control vector (pTracer TUR cells). In contrast, TUR transfectants containing a constitutively active poly(ADP-ribose) polymerase-1 (PARP-1) gene fragment in antisense orientation within the pTracer vector (asPARP TUR cells) demonstrated increasing cell attachment and differentiation after TPA treatment. Moreover, asPARP TUR cells ceased to divide upon TPA stimulation. Cell cycle analysis revealed a predominant G0/G1 arrest and a partial G2/M arrest in TPA-treated asPARP TUR cells, whereas little if any population was detectable in S phase. Microarray gene expression analysis exhibited a significant down-regulation of cell cycle genes in phorbol ester-stimulated asPARP TUR and markedly elevated levels of differentiation-associated factors in contrast to TPA-incubated wild-type TUR cells. Whereas PARP-1 can associate with the 20S proteasome in leukemia cells, a significant reduction of this proteolytic activity was observed in asPARP TUR cells. Conversely, protein levels of manganese superoxide dismutase and the matrix metalloproteinases MMP-1 and MMP-9 were progressively increased in TPA-treated asPARP TUR cells, respectively. These findings underscore an important function of PARP-1 in human leukemia cells to connect cell cycle progression and control of differentiation.     

The discovery and synthesis of novel adenosine substituted 2,3-dihydro-1H-isoindol-1-ones: potent inhibitors of poly(ADP-ribose) polymerase-1 (PARP-1)

A series of novel 4-(N-acyl)-2,3-dihydro-1H-isoindol-1-ones have been prepared from methyl-3-nitro-2-methylbenzoate and linked through various spacers to the adenosine derivatives 11 and 12. We found that potent inhibition of poly(ADP-ribose)polymerase-1 (PARP-1) was achieved when isoindolinone was linked to adenosine by a spacer group of a specific length. Introduction of piperazine and succinyl linkers between the isoindolinone and adenosine core structures resulted in highly potent compounds 8a and 10b, which showed IC(50) values of 45 and 100 nM, respectively.