Design, synthesis and antitumor activities of phthalazinone derivatives as PARP-1 inhibitors and PARP-1/HDAC-1 inhibitors.

In recent years, poly(ADP-ribose)polymerase-1 (PARP-1) and histone deacetylase (HDAC) have emerged as significant targets in tumor therapy, garnering widespread attention. In this study, we designed and synthesized two novel phthalazinone PARP-1 inhibitors and dual PARP-1/HDAC-1 inhibitors, named DLC-1-46 containing dithiocarboxylate fragments and DLC-47-63 containing hydroxamic acid fragments, and evaluated their inhibitory activities on enzymes and cells. Among the PARP-1 inhibitors, most compounds exhibited high inhibitory activity against the PARP-1 enzyme, with DLC-1-6 being particularly notable, showing IC50 values <0.2 nM. Notably, DLC-1 demonstrated significant anti-proliferative activity, with IC50 values for inhibiting the proliferation of MDA-MB-436, MDA-MB-231, and MCF-7 cells reaching 0.08, 26.39, and 1.01 µM, respectively. Further investigation revealed that DLC-1 arrested MDA-MB-231 cells in the G1 phase and induced apoptosis in a dose-dependent manner. Among the designed dual PARP-1/HDAC-1 inhibitors, several compounds exhibited potent dual-target inhibitory activity, with DLC-49 displaying IC50 values of 0.53 nM and 17 nM for PARP-1 and HDAC-1, respectively. DLC-50 demonstrated the most potent anti-proliferative activity, with IC50 values for inhibiting the proliferation of MDA-MB-436, MDA-MB-231, and MCF-7 cells at 0.30, 2.70, and 2.41 µM, respectively. Cell cycle arrest and apoptosis assays indicated that DLC-50 arrested the cell cycle in the G2 phase and induced apoptosis in HCT-116 cells. Our findings present a novel avenue for further exploration of PARP-1 inhibitors and dual PARP-1/HDAC-1 inhibitors.

Comprehensive machine learning boosts structure-based virtual screening for PARP1 inhibitors.

Poly ADP-ribose polymerase 1 (PARP1) is an attractive therapeutic target for cancer treatment. Machine-learning scoring functions constitute a promising approach to discovering novel PARP1 inhibitors. Cutting-edge PARP1-specific machine-learning scoring functions were investigated using semi-synthetic training data from docking activity-labelled molecules: known PARP1 inhibitors, hard-to-discriminate decoys property-matched to them with generative graph neural networks and confirmed inactives. We further made test sets harder by including only molecules dissimilar to those in the training set. Comprehensive analysis of these datasets using five supervised learning algorithms, and protein-ligand fingerprints extracted from docking poses and ligand only features revealed one highly predictive scoring function. This is the PARP1-specific support vector machine-based regressor, when employing PLEC fingerprints, which achieved a high Normalized Enrichment Factor at the top 1% on the hardest test set (NEF1% = 0.588, median of 10 repetitions), and was more predictive than any other investigated scoring function, especially the classical scoring function employed as baseline.

Synthetically accessible de novo design using reaction vectors: Application to PARP1 inhibitors.

De novo design has been a hotly pursued topic for many years. Most recent developments have involved the use of deep learning methods for generative molecular design. Despite increasing levels of algorithmic sophistication, the design of molecules that are synthetically accessible remains a major challenge. Reaction-based de novo design takes a conceptually simpler approach and aims to address synthesisability directly by mimicking synthetic chemistry and driving structural transformations by known reactions that are applied in a stepwise manner. However, the use of a small number of hand-coded transformations restricts the chemical space that can be accessed and there are few examples in the literature where molecules and their synthetic routes have been designed and executed successfully. Here we describe the application of reaction-based de novo design to the design of synthetically accessible and biologically active compounds as proof-of-concept of our reaction vector-based software. Reaction vectors are derived automatically from known reactions and allow access to a wide region of synthetically accessible chemical space. The design was aimed at producing molecules that are active against PARP1 and which have improved brain penetration properties compared to existing PARP1 inhibitors. We synthesised a selection of the designed molecules according to the provided synthetic routes and tested them experimentally. The results demonstrate that reaction vectors can be applied to the design of novel molecules of biological relevance that are also synthetically accessible.

Poly (ADP-Ribose) polymerase 1 and parthanatos in neurological diseases: From pathogenesis to therapeutic opportunities.

Poly (ADP-ribose) polymerase-1 (PARP-1) is the most extensively studied member of the PARP superfamily, with its primary function being the facilitation of DNA damage repair processes. Parthanatos is a type of regulated cell death cascade initiated by PARP-1 hyperactivation, which involves multiple subroutines, including the accumulation of ADP-ribose polymers (PAR), binding of PAR and apoptosis-inducing factor (AIF), release of AIF from the mitochondria, the translocation of the AIF/macrophage migration inhibitory factor (MIF) complex, and massive MIF-mediated DNA fragmentation. Over the past few decades, the role of PARP-1 in central nervous system health and disease has received increasing attention. In this review, we discuss the biological functions of PARP-1 in neural cell proliferation and differentiation, memory formation, brain ageing, and epigenetic regulation. We then elaborate on the involvement of PARP-1 and PARP-1-dependant parthanatos in various neuropathological processes, such as oxidative stress, neuroinflammation, mitochondrial dysfunction, excitotoxicity, autophagy damage, and endoplasmic reticulum (ER) stress. Additional highlight contains PARP-1's implications in the initiation, progression, and therapeutic opportunities for different neurological illnesses, including neurodegenerative diseases, stroke, autism spectrum disorder (ASD), multiple sclerosis (MS), epilepsy, and neuropathic pain (NP). Finally, emerging insights into the repurposing of PARP inhibitors for the management of neurological diseases are provided. This review aims to summarize the exciting advancements in the critical role of PARP-1 in neurological disorders, which may open new avenues for therapeutic options targeting PARP-1 or parthanatos.

[The Role of the WGR Domain in the Functions of PARP1 and PARP2].

The PARP1 and PARP2 proteins are members of the poly(ADP-ribose) polymerase family involved in the regulation of DNA repair and replication, RNA processing, ribosome biogenesis, transcription, cell division, and cell death. PARP1 and PARP2 are promising targets for the development of anticancer drugs and can be used in the treatment of cardiovascular, neurodegenerative, and other disorders. The WGR domain has been shown to play a central role in the functioning of PARP1 and PARP2 proteins. This review considers the mechanisms of functioning of WGR domains in the PARP1 and PARP2 proteins, which have several similar and specialized properties. Understanding these processes is of great interest to fundamental science and can contribute to the development of more effective and selective inhibitors of PARP1 and PARP2.

Liposome Formulations for the Strategic Delivery of PARP1 Inhibitors: Development and Optimization.

The development of a lipid nano-delivery system was attempted for three specific poly (ADP-ribose) polymerase 1 (PARP1) inhibitors: Veliparib, Rucaparib, and Niraparib. Simple lipid and dual lipid formulations with 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1'-glycerol) sodium salt (DPPG) and 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) were developed and tested following the thin-film method. DPPG-encapsulating inhibitors presented the best fit in terms of encapsulation efficiency (>40%, translates into concentrations as high as 100 µM), zeta potential values (below -30 mV), and population distribution (single population profile). The particle size of the main population of interest was ~130 nm in diameter. Kinetic release studies showed that DPPG-encapsulating PARP1 inhibitors present slower drug release rates than liposome control samples, and complex drug release mechanisms were identified. DPPG + Veliparib/Niraparib presented a combination of diffusion-controlled and non-Fickian diffusion, while anomalous and super case II transport was verified for DPPG + Rucaparib. Spectroscopic analysis revealed that PARP1 inhibitors interact with the DPPG lipid membrane, promoting membrane water displacement from hydration centers. A preferential membrane interaction with lipid carbonyl groups was observed through hydrogen bonding, where the inhibitors' protonated amine groups may be the major players in the PARP1 inhibitor encapsulation mode.

3D-QSAR, molecular docking, and molecular dynamics analysis of dihydrodiazaindolone derivatives as PARP-1 inhibitors.

CONTEXT: PARP-1 plays an important role in DNA repair and apoptosis, and PARP-1 inhibitors have shown to be effective in the treatment of several malignancies. To evaluate the function of new PARP-1 inhibitors as anticancer adjuvant medicines, 3D-QSAR, molecular docking, and molecular dynamics (MD) simulations of a sequence of dihydrodiazepinoindolone derivatives PARP-1 inhibitors were undertaken in this study. METHODS: In this paper, 43 PARP-1 inhibitors were studied in a three-dimensional quantitative structure-activity relationship (3D-QSAR) using comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA). CoMFA with q2 of 0.675 and r2 of 0.981 was achieved, as was CoMSIA with q2 of 0.755 and r2 of 0.992. The changed areas of these compounds are shown by steric, electrostatic, hydrophobic, and hydrogen-bonded acceptor field contour maps. Subsequently, molecular docking, and molecular dynamics simulations further confirmed that key residues Gly863 and Ser904 of PARP-1 are vital residues for protein interactions and their binding affinity. The effects of 3D-QSAR, molecular docking and molecular dynamics simulations supply a new route for the search of new PARP-1 inhibitors. Finally, we designed eight new compounds with exact activity and ADME/T properties.

Discovery of novel benzamide derivatives bearing benzamidophenyl and phenylacetamidophenyl scaffolds as potential antitumor agents via targeting PARP-1.

Poly(ADP-ribose) polymerase-1 (PARP-1) plays a crucial role in DNA damage repair and has been identified as a promising therapeutic target in cancer therapy. As a continuation of our efforts on the development of novel PARP-1 inhibitors with potent anticancer activity, a series of benzamide derivatives containing the benzamidophenyl and phenylacetamidophenyl scaffolds were designed and synthesized based on the structure optimization of our previously reported compound IX. All target compounds were screened for their in vitro antiproliferative activities against human colorectal cancer cells (HCT116, DLD-1 and SW480) and human normal colonic epithelial cells (NCM460). Among them, compound 13f exhibited the most potent anticancer activity against HCT116 cells and DLD-1 cells with IC50 = 0.30 µM and 2.83 µM, respectively. Moreover, 13f displayed significant selectivity in inhibiting HCT116 cancer cells over the normal NCM460 cells. Furthermore, 13f exhibited excellent PARP-1 inhibitory effect with IC50 = 0.25 nM. Besides, 13f was found to effectively inhibit colony formation and migration of HCT116 cells. Studies on the mechanisms revealed that 13f could arrest cell cycle at G2/M phase, accumulate DNA double-strand breaks, reduce mitochondrial membrane potential and ultimately induce apoptosis in HCT116 cells. In addition, molecular docking study indicated that 13f could combine firmly with the catalytic pocket of PARP-1 through multiple hydrogen bond interactions. Collectively, these findings demonstrated that 13f could serve as a promising anticancer candidate and deserves further investigation.

An overview of compound properties, multiparameter optimization, and computational drug design methods for PARP-1 inhibitor drugs.

Breast cancer treatment with PARP-1 inhibitors remains challenging due to emerging toxicities, drug resistance, and unaffordable costs of treatment options. How do we invent strategies to design better anti-cancer drugs? A part of the answer is in optimized compound properties, desirability functions, and modern computational drug design methods that drive selectivity and toxicity and have not been reviewed for PARP-1 inhibitors. Nonetheless, comparisons of these compound properties for PARP-1 inhibitors are not available in the literature. In this review, we analyze the physchem, PKPD space to identify inherent desirability functions characteristic of approved drugs that can be valuable for the design of better candidates. Recent literature utilizing ligand, structure-based drug design strategies and matched molecular pair analysis (MMPA) for the discovery of novel PARP-1 inhibitors are also reviewed. Thus, this perspective provides valuable insights into the medchem and multiparameter optimization of PARP-1 inhibitors that might be useful to other medicinal chemists.

Design, synthesis, and evaluation of 1H-benzo[d]imidazole-4-carboxamide PARP-1 inhibitors using different saturated nitrogen-contained heterocycle as linker group.

Poly (ADP-ribose) polymerase-1 (PARP-1) inhibitors have been successfully applied in the clinical treatment of various cancer. Side effects and drug resistant cases were reported, and more effective PARP-1 inhibitors were required. However, studies on the AD site of PARP-1 inhibitors are currently incomplete. Therefore, to synthesize more potential candidate PARP-1 inhibitors and disclose some AD site SAR of the PARP-1 inhibitors, herein, a series of 2-phenyl-benzimidazole-4-carboxamide derivatives using different saturated nitrogen-contained heterocycles as linker group (6a-6t) have been designed, synthesized, and evaluated PARP-1 inhibitory activity and proliferation inhibitory against BRCA-1 mutant MDA-MB-436 cell line in vitro. The results showed 6b (IC50 = 8.65 nM) exhibited the most PARP-1 enzyme inhibitory activity comparable with Veliparib (IC50 = 15.54 nM) and Olaparib (IC50 = 2.77 nM); 6m exhibited the strongest MDA-MB-436 cell anti-proliferation activity (IC50 = 25.36 ± 6.06 µM) comparable with Olaparib (IC50 = 23.89 ± 3.81 µM). The compounds 6b, 6r, and 6m could be potential candidates for effective PARP-1 inhibitors and valuable for further optimization. The analysis of activity data also showed that the holistically anti-proliferation activity of the 1,4-diazepane group was about~twofold than that of the piperazine group. Meanwhile, the terminal 3-methyl-furanyl group exhibited the most robust PARP-1 inhibitory and anti-proliferation activity. It is hoped that the results could benefitable for further optimization of PARP-1 inhibitors. Furthermore, we note that some compounds (6d,6g,6n,6p,6s) showed poor PARP-1 inhibitory (>500 nM) but relatively good anti-proliferation activity, which indicates the proliferation inhibitory mechanism against MDA-MB-436 cell line was worth investigating in-depth.

PARP1 inhibitors induce pyroptosis via caspase 3-mediated gasdermin E cleavage.

The identification of PARP1 as a therapeutic target for BRCA1/2-deficient cells has led to a paradigm shift for the treatment of human malignancies with BRCA1/2 mutations. However, our understanding of the mechanism of action of PARP1 inhibitors (PARPi) is still evolving. It is being increasingly appreciated that the immunomodulatory function of PARPi is a critical contributor of the anti-tumor effects of these compounds. Here, we identify a novel cell death effector pathway for PARPi where PARPi induces inflammatory pyroptosis that is mediated by caspase 3-dependent cleavage of GSDME. Caspase 3 is activated upon PARPi treatment which directly cleaves GSDME and, subsequently induces pyroptosis. Genetic and pharmacological experiments show that the presence of the PARP1 protein with uncompromised DNA binding capability is required for PARPi-induced pyroptosis, suggesting that PARP1 trapping is a key driver of this phenomenon. Importantly, we show that PARPi-induced GSDME cleavage and pyroptosis occurred only in the BRCA1-deficient cells, but not in those reconstituted with BRCA1 wild-type (WT). These findings suggest that pyroptosis could be a novel aspect of the immunomodulatory function of PARPi. Our studies could also offer new insights to the potential biomarkers and therapeutic strategies to achieve better anti-tumor effects of PARPi for BRCA-deficient tumors with low GSDME expression.

Selective PARP1 inhibitors, PARP1-based dual-target inhibitors, PROTAC PARP1 degraders, and prodrugs of PARP1 inhibitors for cancer therapy.

Poly ADP-ribose polymerase (PARP) plays a critical role in many cellular processes such as DNA damage repair, gene transcription and cell apoptosis. Therefore, targeting PARP represents a promising strategy for cancer therapy. To date, numerous small molecule PARP1 inhibitors have been identified, but many of them suffer from limited clinical efficacy and serious toxicity. Hence, PARP1 inhibitor-based combination therapies, and other PARP1 modulators (e.g. PROTAC degraders, dual acting agents) have attracted great attention with significant advancements achieved in the past few years. In this review, we overviewed the recent progress on PARP1-based drug discovery with a focus on PARP1 inhibitor-based drug combination therapy and other PARP1-targeting strategies (e.g. selective PARP1 inhibitors, PARP1-based dual-target inhibitors, PROTAC PARP1 degraders, and prodrugs of PARP1 inhibitors). In addition, we also summarized the reported co-crystal structures of PARP1 inhibitors in complex with their target proteins as well as the binding interactions. Finally, the challenges and future directions for PARP-based drug discovery in cancer therapy are also discussed in detail.

Interactions of PARP1 Inhibitors with PARP1-Nucleosome Complexes.

Inhibitors (PARPi) of poly(ADP-ribose-)polymerase-1 (PARP1) are used in antitumor therapy; their cytotoxicity correlates with the efficiency of PARP1 trapping in cell chromatin. Previous studies have demonstrated the PARPi-induced trapping of PARP1 on DNA, although details of the mechanism remain controversial. Here, the interactions of PARP1-nucleosome complexes with PARPi, olaparib (Ola), talazoparib (Tala), and veliparib (Veli) were studied. PARPi trap PARP1 on nucleosomes without affecting the structure of PARP1-nucleosome complexes. The efficiency of PARP1 trapping on nucleosomes increases in the order of Tala>Ola>>Veli, recapitulating the relative trapping efficiencies of PARPi in cells, but different from the relative potency of PARPi to inhibit the catalytic activity of PARP1. The efficiency of PARP1 trapping on nucleosomes correlates with the level of inhibition of auto-PARylation, which otherwise promotes the dissociation of PARP1-nucleosome complexes. The trapping efficiencies of Tala and Ola (but not Veli) are additionally modulated by the enhanced PARP1 binding to nucleosomes. The dissociation of PARP1-nucleosome complexes occurs without a loss of histones and leads to the restoration of the intact structure of nucleosomal DNA. The data suggest that the chromatin structure can considerably affect the efficiency of the PARPi action.

Design, synthesis, biological evaluation and molecular docking study of novel urea-based benzamide derivatives as potent poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors.

Poly(ADP-ribose) polymerase-1 (PARP-1) is one of the key members of DNA repair enzymes that is responsible for the repair of DNA single-strand breaks. Inhibition of PARP-1 has been demonstrated to be a promising strategy to selectively kill tumor cells by targeting DNA repair pathway. Herein, a series of novel urea-based benzamide derivatives were designed and synthesized based on the structure-based drug design strategy. The anticancer activities against five human cancer cell lines including HCT116, MDA-MB-231, HeLa, A579 and A375 were evaluated and the preliminary structure-activity relationships were summarized. Among them, compounds 23f and 27f exhibited potent antiproliferative effects against HCT116 cells with IC50 values of 7.87 µM and 8.93 µM, respectively. Moreover, both compounds displayed excellent PARP-1 inhibitory activities with IC50 values of 5.17 nM and 6.06 nM, respectively. Mechanistic investigations showed that 23f and 27f could effectively inhibit colony formation and cell migration of HCT116 cells. Furthermore, 23f and 27f could cause cell cycle arrest at G2/M phase, and induce apoptosis by upregulating the expression of Bax and cleaved Caspase-3 and downregulating the expression of Caspase-3 and Bcl-2 in HCT116 cells. In addition, molecular docking studies provided the rational binding modes of these compounds in complex with PARP-1. Collectively, these results suggested that 23f and 27f could serve as promising drug candidates for further investigation.

DNA damage response signaling pathways as important targets for combination therapy and chemotherapy sensitization in osteosarcoma.

Osteosarcoma (OS) is the most common bone malignancy that occurs most often in young adults, and adolescents with a survival rate of 20% in its advanced stages. Nowadays, increasing the effectiveness of common treatments used in OS has become one of the main problems for clinicians due to cancer cells becoming resistant to chemotherapy. One of the most important mechanisms of resistance to chemotherapy is through increasing the ability of DNA repair because most chemotherapy drugs damage the DNA of cancer cells. DNA damage response (DDR) is a signal transduction pathway involved in preserving the genome stability upon exposure to endogenous and exogenous DNA-damaging factors such as chemotherapy agents. There is evidence that the suppression of DDR may reduce chemoresistance and increase the effectiveness of chemotherapy in OS. In this review, we aim to summarize these studies to better understand the role of DDR in OS chemoresistance in pursuit of overcoming the obstacles to the success of chemotherapy.

Neuroprotective Effects of PARP Inhibitors in Drosophila Models of Alzheimer's Disease.

Alzheimer's disease (AD) is an irreversible age-related neurodegenerative disorder clinically characterized by severe memory impairment, language deficits and cognitive decline. The major neuropathological hallmarks of AD include extracellular deposits of the ß-amyloid (Aß) peptides and cytoplasmic neurofibrillary tangles (NFTs) of hyperphosphorylated tau protein. The accumulation of plaques and tangles in the brain triggers a cascade of molecular events that culminate in neuronal damage and cell death. Despite extensive research, our understanding of the molecular basis of AD pathogenesis remains incomplete and a cure for this devastating disease is still not available. A growing body of evidence in different experimental models suggests that poly(ADP-ribose) polymerase-1 (PARP-1) overactivation might be a crucial component of the molecular network of interactions responsible for AD pathogenesis. In this work, we combined genetic, molecular and biochemical approaches to investigate the effects of two different PARP-1 inhibitors (olaparib and MC2050) in Drosophila models of Alzheimer's disease by exploring their neuroprotective and therapeutic potential in vivo. We found that both pharmacological inhibition and genetic inactivation of PARP-1 significantly extend lifespan and improve the climbing ability of transgenic AD flies. Consistently, PARP-1 inhibitors lead to a significant decrease of Aß42 aggregates and partially rescue the epigenetic alterations associated with AD in the brain. Interestingly, olaparib and MC2050 also suppress the AD-associated aberrant activation of transposable elements in neuronal tissues of AD flies.

Recent Progress in the Research on Benzimidazole PARP-1 Inhibitors.

Poly (ADP-ribose) polymerase-1 (PARP-1) is a multifunctional protein that plays an important role in DNA repair and genome integrity. PARP-1 inhibitors can be used as effective drugs not only to treat BRCA-1/2 deficient cancers because of the synthetic lethality effect but also to treat non- BRCA1/2 deficient tumours because of the effect of PARP capture. Therefore, PARP inhibitors have become a focus of compelling research. Among these inhibitors, substituted benzimidazole derivatives were mainly concerned as lead compounds. However, the commercially available benzimidazole PARP-1 inhibitors have some shortcomings, such as serious toxicity in combination with chemotherapy drugs and in vivo cardiovascular side effects such as anemia. Therefore it is crucial for scientists to explore more structure-activity relationships of the benzimidazole PARP-1 inhibitors and access safer and more effective PARP inhibitors. As the binding regions of PARP-1 and the substrates are usually characterized by NI site and AD site, the modification of benzimidazoles mainly occurs on the benzimidazole skeleton (NI site) and the side chain of benzimidazole in the 2-C position (AD site). Herein, the recent progress in the research on benzamides PARP inhibitors was introduced. We noticed that even though many efforts were made to the modification of NI sites, there was still a lack of optimistic and impressive results. However, the structure-activity relationships of the modification of AD sites have not been thoroughly discovered yet. We hope that enlightened by the previous research, more research on AD sites should be carried out, and more effective benzimidazole PARP-1 inhibitors could be designed, synthesized, and applied to clinics.

DNA Repair Enzyme Poly(ADP-Ribose) Polymerase 1/2 (PARP1/2)-Targeted Nuclear Imaging and Radiotherapy.

Since it was discovered that many tumor types are vulnerable to inhibition of the DNA repair machinery, research towards efficient and selective inhibitors has accelerated. Amongst other enzymes, poly(ADP-ribose)-polymerase 1 (PARP1) was identified as a key player in this process, which resulted in the development of selective PARP inhibitors (PARPi) as anti-cancer drugs. Most small molecule PARPi's exhibit high affinity for both PARP1 and PARP2. PARPi are under clinical investigation for mono- and combination therapy in several cancer types and five PARPi are now clinically approved. In parallel, radiolabeled PARPi have emerged for non-invasive imaging of PARP1 expression. PARP imaging agents have been suggested as companion diagnostics, patient selection, and treatment monitoring tools to improve the outcome of PARPi therapy, but also as stand-alone diagnostics. We give a comprehensive overview over the preclinical development of PARP imaging agents, which are mostly based on the PARPi olaparib, rucaparib, and recently also talazoparib. We also report on the current status of clinical translation, which involves a growing number of early phase trials. Additionally, this work provides an insight into promising approaches of PARP-targeted radiotherapy based on Auger and α-emitting isotopes. Furthermore, the review covers synthetic strategies for PARP-targeted imaging and therapy agents that are compatible with large scale production and clinical translation.

The potential role of the combined PARP-1 and VEGF inhibition in severe SARS-CoV-2 (COVID-19) infection.

INTRODUCTION: During the evolution of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, several drug candidates have been proposed for repositioning towards a quest for more effective treatments. METHODOLOGY: We reviewed recent literature (Pubmed, Google, Clinicaltrials.gov), as of the middle of May 2021, for evidence regarding the potential benefit from poly(ADP-ribose)-polymerase inhibitors and vascular endothelial growth factor blockade in severe SARS-CoV-2 infection. RESULTS: poly(ADP-ribose)-polymerase inhibitors have been suggested as potential agents against coronavirus disease 2019 (COVID-19) by a variety of mechanisms. vascular endothelial growth factor-associated vascular permeability is implicated with increased vascular leakage and pulmonary oedema. Thus, anti-angiogenesis factors, such as bevacizumab are being investigated in critically ill COVID-19 patients. CONCLUSIONS: The synergistic potential of these two classes of inhibitors in severe COVID-19 management could be beneficial. Further research should be carried out in order to support this hypothesis.

Exclusive modifications of NuMA in malignant epithelial cells: A potential therapeutic mechanism.

NuMA (nuclear mitotic apparatus) protein is indispensable in the mitosis of human proliferating cells, both malignant and benign. The progression of mitosis requires stable spindles, which depend on the bipolar clustering of NuMA within the spindles. The phenanthridine PJ34 kills malignant epithelial cells during mitosis and targets NuMA. PJ34 treated healthy cells are not impaired. PJ34 exclusively blocks the post-translational modification of NuMA in a variety of malignant epithelial cells, but not in benign cells. This blockage of the post-translational modification of NuMA affects its protein-binding capacity, causing construction faults in the mitotic spindle poles of PJ34-treated cancer cells, leading to Mitotic Catastrophe cell death. PJ34 is a potent PARP1 inhibitor. Therefore its PARP independent exclusive cytotoxicity in human malignant cells, challenges the currently accepted notion that inhibition of PARP1 halts cancer by preventing DNA repair. Certain molecules that act as PARP1 inhibitors kill cancer cells by targeting other proteins and vital mechanisms.