PARP-1, a determinant of cell survival in response to DNA damage

Combined effects of carbon ion radiation and PARP inhibitor on non-small cell lung carcinoma cells: Insights into DNA repair pathways and cell death mechanisms

The utilization of high linear energy transfer (LET) carbon ion (12C-ion) in radiotherapy has witnessed a notable rise in managing highly metastatic, recurrent, and chemo/radio-resistant human cancers. Non-small cell lung cancer (NSCLC) presents a formidable challenge due to its chemo-resistance and aggressive nature, resulting in poor prognosis and survival rates. In a previous study, we demonstrated that the combination of 12C-ion with the poly (ADP-ribose) polymerase (PARP) inhibitor (PARPi) olaparib significantly mitigated metastasis in A549 cells. Here, we delve into the underlying rationale behind the combined action of olaparib with 12C-ion, focusing on DNA repair pathways and cell death mechanisms in asynchronous NSCLC A549 cells following single and combined treatments. Evaluation included analysis of colony-forming ability, DNA damage assessed by γH2AX foci, expression profiling of key proteins involved in Homologous Recombination (HR) and Non-Homologous End Joining (NHEJ) repair pathways, caspase-3 activation, apoptotic body formation, and autophagic cell death. Our findings reveal that both PARPi olaparib and rucaparib sensitize A549 cells to 12C-ion exposure, with olaparib exhibiting superior sensitization. Moreover, 12C-ion exposure alone significantly downregulates both HR and NHEJ repair pathways by reducing the expression of MRE11--RAD51 and Ku70-Ku80 protein complexes at 24 h post-treatment. Notably, the combination of olaparib pre-treatment with 12C-ion markedly inhibits both HR and NHEJ pathways, culminating in DNA damage-induced apoptotic and autophagic cell death. Thus we are the first to demonstrate that olaparib sensitizes NSCLC cells to carbon ion by interfering with HR and NHEJ pathway. These insights underscore the promising therapeutic potential of combining PARP inhibition with carbon ion exposure for effective NSCLC management.

PARP1 acetylation at K119 is essential in regulating the progression and proliferation of cervical cancer cells

Cervical cancer, CC, is one of the malignant cancers in women worldwide. Many studies about the genesis and progression of CC have been done at genomic, transcriptional, translational, and epigenetic levels. However, much less is done at post-translational modification (PTM) level. We first used pan-PTM antibodies to compare the pan PTM levels between clinical normal cervical tissues and CC tissues; we then sent the selected samples for label-free identification of acetylation sites. Next, we employed WT or K119A mutant PARP1-EGFP-STREPII plasmid transfection in Hela cells and examined various indexes including colony formation, wound healing, ROS generation, early apoptosis, and immunofluorescence and quantification of proliferation markers (Ki67, PCNA, and p-P53). Last, we examined the levels of multiple important kinases regulating cervical cancer progression. We found that pan-acetylation was the most downregulated in clinical CC samples, whereas the acetylation of PARP1, Poly(ADP-ribose) polymerase-1, was upregulated at K119. Next, we showed that PARP1-WT overexpression significantly suppressed the proliferation and progression in CC cell line Hela, while K119A overexpression didn't show any impact. Finally, PARP1-WT overexpression significantly decreased p-ERK1/2 while didn't affect the phosphorylation levels of other important kinases such as AKT, MTOR, and RPS6. This study discovered a new type of PTM of PARP1 in CC, and showed that PARP1 acetylation at K119 is essential in regulating the proliferation and progression of CC through ERK1/2. Further studies are required to investigate how PARP1 acetylation impact its function.

Cancer therapeutic potential of hovetrichoside C from Jatropha podagrica on apoptosis of MDA-MB-231 human breast cancer cells

Phytochemical analysis of the methanolic extracts of Jatropha podagrica stalks and roots using liquid chromatography-mass spectrometry (LC-MS) led to the isolation of six compounds: corchoionoside C (1), isobiflorin (2), fraxin (3), hovetrichoside C (4), fraxetin (5), and corillagin (6). The isolated compounds (1-6) were tested for their cytotoxicity against MDA-MB-231 human breast cancer cells. Remarkably, compound 4 (hovetrichoside C) exhibited robust cytotoxicity against MDA-MB-231 cells, displaying an IC50 value of 50.26 ± 1.22 μM, along with an apoptotic cell death rate of 24.21 ± 2.08% at 100 μM. Treatment involving compound 4 amplified protein levels of cleaved caspase-8, -9, -3, -7, BH3-interacting domain death agonist (Bid), Bcl-2-associated X protein (Bax), and cleaved poly (ADP-ribose) polymerase (cleaved PARP), while concurrently reducing B-cell lymphoma 2 (Bcl-2) levels. In totality, these findings underscore that hovetrichoside C (4) possesses anti-breast cancer activity that revolves around apoptosis induction via both extrinsic and intrinsic signaling pathways.

Surviving in a multistressor world: Gene expression changes in earthworms exposed to heat, desiccation, and chemicals

An investigation of the effects of anthropogenic stress on terrestrial ecosystems is urgently needed. In this work, we explored how exposure to heat, desiccation, and chemical stress alters the expression of genes that encode heat shock proteins (HSPs), an enzyme that responds to oxidative stress (CAT), hypoxia-related proteins (HIF1 and HYOU), and a DNA repair-related protein (PARP1) in the earthworm Eisenia fetida. Exposure to heat (31°C) for 24 h upregulated HSPs and hypoxia-related genes, suggesting possible acquired thermotolerance. Desiccation showed a similar expression profile; however, the HSP response was activated to a lesser extent. Heat and desiccation activated the small HSP at 24 h, suggesting that they may play a role in adaptation. Simultaneous exposure to endosulfan and temperature for 7 h upregulated all of the evaluated genes, implicating a coordinated response involving multiple biological processes to ensure survival and acclimation. These results highlight the relevance of multistress analysis in terrestrial invertebrates.

Multi-functionalization of reduced graphene oxide nanosheets for tumor theragnosis: Synthesis, characterization, enzyme assay, in-silico study, radiolabeling and in vivo targeting evaluation

BACKGROUND

In this study, a combination of nanotechnology, organic synthesis and radiochemistry were utilized in order to design an efficient nano-system conjugated with a suitable radionuclide and an antitumor agent for possible application as tumor theragnostic agent.

METHOD

Four novel compounds (3 and 4a-c) bearing tetrahydroquinazoline-7-sulfonohydrazide or 1,2,3,4-tetrahydroquinazoline-7-sulfonamide scaffold were designed. Then, docking study predicted that the compounds can be considered as potential inhibitors for PARP-1. Following that; the four compounds were synthesized and properly characterized using 1HNMR, 13CNMR, IR and Mass spectroscopy. The cytotoxic effect of the four compounds was evaluated against breast cancer cell line (MDA-MB-436), where compound 3 showed the most promising cytotoxic effect. The inhibitory effect of the four compounds was evaluated in vitro against PARP-1.

RESULT

Carboxylated graphene oxide nanosheets (NGO-COOH) were synthesized by a modified Hummer's method and has size of range 40 nm. The NGO-COOH nanosheets were proven to be safe and biocompatible when tested in vitro against normal human lung fibroblast cells (MRC-5). The prepared NGO-COOH nanosheets were conjugated with compound 3 then radiolabeled with 99mTc to yield 99mTc-NGO-COOH-3 with a radiochemical yield of 98.5.0 ± 0.5%. 99mTc-NGO-COOH-3 was injected intravenously in solid tumor bearing mice to study the degree of localization of the nano-system at tumor tissue. The results of the study revealed, excellent localization and retention of the designed nano-system at tumor tissues with targeting ratio of 9.0.

CONCLUSION

Stirred a new candidate tumor theragnostic agent that is safe, selective and stable.

Use of Optical Redox Imaging to Quantify Alveolar Macrophage Redox State in Infants: Proof of Concept Experiments in a Murine Model and Human Tracheal Aspirates Samples

Emerging data indicate that lung macrophages (LM) may provide a novel biomarker to classify disease endotypes in bronchopulmonary dysplasia (BPD), a form of infant chronic lung disease, and that augmentation of the LM phenotype may be a potential therapeutic target. To contribute to this area of research, we first used Optical Redox Imaging (ORI) to characterize the responses to H2O2-induced oxidative stress and caffeine treatment in an in vitro model of mouse alveolar macrophages (AM). H2O2 caused a dose-dependent decrease in NADH and an increase in FAD-containing flavoproteins (Fp) and the redox ratio Fp/(NADH + Fp). Caffeine treatment did not affect Fp but significantly decreased NADH with doses of ≥50 µM, and 1000 µM caffeine treatment significantly increased the redox ratio and decreased the baseline level of mitochondrial ROS (reactive oxygen species). However, regardless of whether AM were pretreated with caffeine or not, the mitochondrial ROS levels increased to similar levels after H2O2 challenge. We then investigated the feasibility of utilizing ORI to examine macrophage redox status in tracheal aspirate (TA) samples obtained from premature infants receiving invasive ventilation. We observed significant heterogeneity in NADH, Fp, Fp/(NADH + Fp), and mitochondrial ROS of the TA macrophages. We found a possible positive correlation between gestational age and NADH and a negative correlation between mean airway pressure and NADH that provides hypotheses for future testing. Our study demonstrates that ORI is a feasible technique to characterize macrophage redox state in infant TA samples and supports further use of this method to investigate lung macrophage-mediated disease endotypes in BPD.

Bi-directional regulation of AIMP2 and its splice variant on PARP-1-dependent neuronal cell death; Therapeutic implication for Parkinson's disease

BACKGROUND

Parthanatos represents a critical molecular aspect of Parkinson's disease, wherein AIMP2 aberrantly activates PARP-1 through direct physical interaction. Although AIMP2 ought to be a therapeutic target for the disease, regrettably, it is deemed undruggable due to its non-enzymatic nature and predominant localization within the tRNA synthetase multi-complex. Instead, AIMP2 possesses an antagonistic splice variant, designated DX2, which counteracts AIMP2-induced apoptosis in the p53 or inflammatory pathway. Consequently, we examined whether DX2 competes with AIMP2 for PARP-1 activation and is therapeutically effective in Parkinson's disease.

METHODS

The binding affinity of AIMP2 and DX2 to PARP-1 was contrasted through immunoprecipitation. The efficacy of DX2 in neuronal cell death was assessed under 6-OHDA and H2O2 in vitro conditions. Additionally, endosomal and exosomal activity of synaptic vesicles was gauged in AIMP2 or DX2 overexpressed hippocampal primary neurons utilizing optical live imaging with VAMP-vGlut1 probes. To ascertain the role of DX2 in vivo, rotenone-induced behavioral alterations were compared between wild-type and DX2 transgenic animals. A DX2-encoding self-complementary adeno-associated virus (scAAV) was intracranially injected into 6-OHDA induced in vivo animal models, and their mobility was examined. Subsequently, the isolated brain tissues were analyzed.

RESULTS

DX2 translocates into the nucleus upon ROS stress more rapidly than AIMP2. The binding affinity of DX2 to PARP-1 appeared to be more robust compared to that of AIMP2, resulting in the inhibition of PARP-1 induced neuronal cell death. DX2 transgenic animals exhibited neuroprotective behavior in rotenone-induced neuronal damage conditions. Following a single intracranial injection of AAV-DX2, both behavior and mobility were consistently ameliorated in neurodegenerative animal models induced by 6-OHDA.

CONCLUSION

AIMP2 and DX2 are proposed to engage in bidirectional regulation of parthanatos. They physically interact with PARP-1. Notably, DX2's cell survival properties manifest exclusively in the context of abnormal AIMP2 accumulation, devoid of any tumorigenic effects. This suggests that DX2 could represent a distinctive therapeutic target for addressing Parkinson's disease in patients.

Cobalt-induced apoptosis of cochlear organotypic cultures and HEI-OC1 cells is mediated by Dicer

Cobalt is widely used in the medical industry, mainly including cobalt alloy joint implants and cobalt-chromium porcelain crowns. However, unexplained ototoxicity and neurotoxicity often occur in the clinical use of cobalt agents at present, which limits the development of the cobalt industry. In this study, based on the clinical problem of cobalt ototoxicity, we first conducted an extensive search and collation of related theories, and on this basis, prepared an HEI-OC1 cell model and basilar membrane organotypic cultures after cobalt treatment. We used immunofluorescence staining, western blot, CCK8, and si-RNA to investigate the mechanism of cobalt ototoxicity, to discover its potential therapeutic targets. After comparing the reactive oxygen species, mitochondrial transmembrane potential, apoptosis-related protein expression, and cell viability of different treatment groups, the following conclusions were drawn: cobalt causes oxidative stress in the inner ear, which leads to apoptosis of inner ear cells; inhibition of oxidative stress and apoptosis can alleviate the damage of cobalt on inner ear cells; and the Dicer protein plays a role in the mechanism of inner ear damage and is a potential target for the treatment of cobalt-induced inner ear damage. Taken together, these results suggest that cobalt-induced ototoxicity triggered by oxidative stress activates a cascade of apoptotic events where cCaspase-3 decreases Dicer levels and amplifies this apoptotic pathway. It may be possible to prevent and treat cobalt ototoxicity by targeting this mechanism.

Targeting of RRM2 suppresses DNA damage response and activates apoptosis in atypical teratoid rhabdoid tumor

BACKGROUND

Atypical teratoid rhabdoid tumors (ATRT) is a rare but aggressive malignancy in the central nervous system, predominantly occurring in early childhood. Despite aggressive treatment, the prognosis of ATRT patients remains poor. RRM2, a subunit of ribonucleotide reductase, has been reported as a biomarker for aggressiveness and poor prognostic conditions in several cancers. However, little is known about the role of RRM2 in ATRT. Uncovering the role of RRM2 in ATRT will further promote the development of feasible strategies and effective drugs to treat ATRT.

METHODS

Expression of RRM2 was evaluated by molecular profiling analysis and was confirmed by IHC in both ATRT patients and PDX tissues. Follow-up in vitro studies used shRNA knockdown RRM2 in three different ATRT cells to elucidate the oncogenic role of RRM2. The efficacy of COH29, an RRM2 inhibitor, was assessed in vitro and in vivo. Western blot and RNA-sequencing were used to determine the mechanisms of RRM2 transcriptional activation in ATRT.

RESULTS

RRM2 was found to be significantly overexpressed in multiple independent ATRT clinical cohorts through comprehensive bioinformatics and clinical data analysis in this study. The expression level of RRM2 was strongly correlated with poor survival rates in patients. In addition, we employed shRNAs to silence RRM2, which led to significantly decrease in ATRT colony formation, cell proliferation, and migration. In vitro experiments showed that treatment with COH29 resulted in similar but more pronounced inhibitory effect. Therefore, ATRT orthotopic mouse model was utilized to validate this finding, and COH29 treatment showed significant tumor growth suppression and prolong overall survival. Moreover, we provide evidence that COH29 treatment led to genomic instability, suppressed homologous recombinant DNA damage repair, and subsequently induced ATRT cell death through apoptosis in ATRT cells.

CONCLUSIONS

Collectively, our study uncovers the oncogenic functions of RRM2 in ATRT cell lines, and highlights the therapeutic potential of targeting RRM2 in ATRT. The promising effect of COH29 on ATRT suggests its potential suitability for clinical trials as a novel therapeutic approach for ATRT.

Small molecule tractable PARP inhibitors: Scaffold construction approaches, mechanistic insights and structure activity relationship

Diverse drug design strategies viz. molecular hybridization, substituent installation, scaffold hopping, isosteric replacement, high-throughput screening, induction and separation of chirality, structure modifications of phytoconstituents and use of structural templates have been exhaustively leveraged in the last decade to load the chemical toolbox of PARP inhibitors. Resultantly, numerous promising scaffolds have been pinpointed that in turn have led to the resuscitation of the credence to PARP inhibitors as cancer therapeutics. This review briefly presents the physiological functions of PARPs, the pharmacokinetics, and pharmacodynamics, and the interaction profiles of FDA-approved PARP inhibitors. Comprehensively covered is the section on the drug design strategies employed by drug discovery enthusiasts for furnishing PARP inhibitors. The impact of structural variations in the template of designed scaffolds on enzymatic and cellular activity (structure-activity relationship studies) has been discussed. The insights gained through the biological evaluation such as profiling of physicochemical properties andin vitroADME properties, PK assessments, and high-dose pharmacology are covered.

Unveiling the vulnerabilities of synthetic lethality in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most invasive molecular subtype of breast cancer (BC), accounting for about nearly 15% of all BC cases reported annually. The absence of the three major BC hormone receptors, Estrogen (ER), Progesterone (PR), and Human Epidermal Growth Factor 2 (HER2) receptor, accounts for the characteristic "Triple negative" phraseology. The absence of these marked receptors makes this cancer insensitive to classical endocrine therapeutic approaches. Hence, the available treatment options remain solemnly limited to only conventional realms of chemotherapy and radiation therapy. Moreover, these therapeutic regimes are often accompanied by numerous treatment side-effects that account for early distant metastasis, relapse, and shorter overall survival in TNBC patients. The rigorous ongoing research in the field of clinical oncology has identified certain gene-based selective tumor-targeting susceptibilities, which are known to account for the molecular fallacies and mutation-based genetic alterations that develop the progression of TNBC. One such promising approach is synthetic lethality, which identifies novel drug targets of cancer, from undruggable oncogenes or tumor-suppressor genes, which cannot be otherwise clasped by the conventional approaches of mutational analysis. Herein, a holistic scientific review is presented, to undermine the mechanisms of synthetic lethal (SL) interactions in TNBC, the epigenetic crosstalks encountered, the role of Poly (ADP-ribose) polymerase inhibitors (PARPi) in inducing SL interactions, and the limitations faced by the lethal interactors. Thus, the future predicament of synthetic lethal interactions in the advancement of modern translational TNBC research is assessed with specific emphasis on patient-specific personalized medicine.

Moringa oleifera: A Review on the Antiproliferative Potential in Breast Cancer Cells

The global burden of female breast cancer and associated deaths has become a major concern. Many chemotherapeutic agents, such as doxorubicin, have been shown to have adverse side effects. The development of multi-drug resistance is a common occurrence, contributing to chemotherapeutic failure. The resistance of breast cancer cells to drug treatment leads to a decline in the treatment efficacy and an increase in cancer recurrence. Therefore, action is required to produce alternative drug therapies, such as herbal drugs. Herbal drugs have been proven to be beneficial in treating illnesses, including cancer. This review aims to highlight the antiproliferative potential of Moringa oleifera (MO), a medicinal tree native to India and indigenous to Africa, in breast cancer cells. Although MO is not yet considered a commercial chemopreventive drug, previous studies have indicated that it could become a chemotherapeutic agent. The possible antiproliferative potential of MO aqueous leaf extract has been previously proven through its antioxidant potential as well as its ability to induce apoptosis. This review will provide an increased understanding of the effect that MO aqueous leaf extract could potentially have against breast cancer.

2,4-Diaryl-pyrimido[1,2-a]benzimidazole derivatives as novel anticancer agents endowed with potent anti-leukemia activity: Synthesis, biological evaluation and kinase profiling

Acute myeloid leukemia (AML) stands as one of the most aggressive type of human cancer that can develop rapidly and thus requires immediate management. In the current study, the development of novel derivatives of pyrimido[1,2-a]benzimidazole (5a-p) as potential anti-AML agents is reported. The prepared compounds 5a-p were inspected for their in vitro anti-tumor activity at NCI-DTP and subsequently 5h was selected for full panel five-dose screening to assess its TGI, LC₅₀ and GI₅₀ values. Compound 5h showed effective anti-tumor activity at low micromolar concentration on all tested human cancer cell lines with GI₅₀ range from 0.35 to 9.43 μM with superior sub-micromolar activity towards leukemia. Furthermore, pyrimido[1,2-a]benzimidazoles 5e-l were tested on a panel ofhuman acute leukemia cell lines, namely HL60, MOLM-13, MV4-11, CCRF-CEM and THP-1, where 5e-h reached single-digit micromolar GI₅₀ values for all the tested cell lines. All prepared compounds were first tested for inhibitory action against the leukemia-associated mutant FLT3-ITD, as well as against ABL, CDK2, and GSK3 kinases, in order to identify the kinase target for the herein described pyrimido[1,2-a]benzimidazoles. However, the examined molecules disclosed non-significant activity against these kinases. Thereafter, a kinase profiling on a panel of 338 human kinases was then used to discover the potential target. Interestingly, pyrimido[1,2-a]benzimidazoles 5e and 5h significantly inhibited BMX kinase. Further investigation for the effect on cell cycle of HL60 and MV4-11 cells and caspase 3/7 activity was also performed. In addition, the changes in selected proteins (PARP-1, Mcl-1, pH3-Ser10) associated with cell death and viability were analyzed in HL60 and MV4-11 cells by immunoblotting.

Changing ROS, NAD and AMP: A path to longevity via mitochondrial therapeutics

Lifespan of many organisms, from unicellular yeast to extremely complex human organism, strongly depends on the genetic background and environmental factors. Being among most influential target energy metabolism is affected by macronutrients, their caloric values, and peculiarities of catabolism. Mitochondria are central organelles that respond for energy metabolism in eukaryotic cells. Mitochondria generate reactive oxygen species (ROS), which are lifespan modifying metabolites and a kind of biological clock. Oxidized nicotinamide adenine dinucleotide (NAD⁺) and adenosine monophosphate (AMP) are important metabolic intermediates and molecules that trigger or inhibit several signaling pathways involved in gene silencing, nutrient allocation, and cell regeneration and programmed death. A part of NAD⁺ and AMP metabolism is tied to mitochondria. Using substances that able to target mitochondria, as well as allotopic expression of specific enzymes, are envisioned to be innovative approaches to prolong lifespan by modulation of ROS, NAD⁺, and AMP levels. Among substances, an anti-diabetic drug metformin is believed to increase NAD⁺ and AMP levels, indirectly influencing histone deacetylases, involved in gene silencing, and AMP-activated protein kinase, an energy sensor of cells. Mitochondrially targeted derivatives of ubiquinone were found to interact with ROS. A mitochondrially targeted non-proton-pumping NADH dehydrogenase may influence both ROS and NAD⁺ levels. Chapter describes putative how mitochondria-targeted drugs and NADH dehydrogenase extend lifespan, perspectives of creating drugs with similar properties and their usage as senotherapeutic pills are discussed in the chapter.

Disturbance of cellular calcium homeostasis plays a pivotal role in glyphosate-based herbicide-induced oxidative stress

Glyphosate-based herbicides (GBHs) are the most worldwide used pesticides. The wide application of GBHs contaminates the soil and, consequently, water and food resources reaching human consumption. GBHs induce oxidative stress in non-target organisms, leading to a pro-inflammatory and pro-apoptotic cellular status, promoting tissue dysfunction and, thus, metabolic and neurobehavioral changes. This review presents evidence of oxidative damage induced by GBHs and the mechanism of cell damage and health consequences. To summarize, exposure to GBHs may induce disorders in calcium homeostasis related to the activation of ion channels. Also, alterations in pathways related to redox state regulation must have a primordial role in oxidative stress caused by GBHs.

Stress and Kynurenine-Inflammation Pathway in Major Depressive Disorder

Major depressive disorder (MDD) is one of the most prevalent disorders and causes severe damage to people's quality of life. Lifelong stress is one of the major villains in triggering MDD. Studies have shown that both stress and MDD, especially the more severe conditions of the disorder, are associated with inflammation and neuroinflammation and the relationship to an imbalance in tryptophan metabolism towards the kynurenine pathway (KP) through the enzymes indoleamine-2,3-dioxygenase (IDO), which is mainly stimulated by pro-inflammatory cytokines and tryptophan-2,3-dioxygenase (TDO) which is activated primarily by glucocorticoids. Considering that several pathophysiological mechanisms of MDD underlie or interact with biological processes from KP metabolites, this chapter addresses and discusses the function of these mechanisms. Activities triggered by stress and the hypothalamic-pituitary-adrenal (HPA) axis and immune and inflammatory processes, in addition to epigenetic phenomena and the gut-brain axis (GBA), are addressed. Finally, studies on the function and mechanisms of physical exercise in the KP metabolism and MDD are pointed out and discussed.

Biological function, mediate cell death pathway and their potential regulated mechanisms for post-mortem muscle tenderization of PARP1: A review

Tenderness is a key attribute of meat quality that affects consumers' willingness to purchase meat. Changes in the physiological environment of skeletal muscles following slaughter can disrupt the balance of redox homeostasis and may lead to cell death. Excessive accumulation of reactive oxygen species (ROS) in the myocytes causes DNA damage and activates poly ADP-ribose polymerase 1 (PARP1), which is involved in different intracellular metabolic pathways and is known to affect muscle tenderness during post-slaughter maturation. There is an urgent requirement to summarize the related research findings. Thus, this paper reviews the current research on the protein structure of PARP1 and its metabolism and activation, outlines the mechanisms underlying the function of PARP1 in regulating muscle tenderness through cysteine protease 3 (Caspase-3), oxidative stress, heat shock proteins (HSPs), and energy metabolism. In addition, we describe the mechanisms of PARP1 in apoptosis and necrosis pathways to provide a theoretical reference for enhancing the mature technology of post-mortem muscle tenderization.

The potential of PARP inhibitors in targeted cancer therapy and immunotherapy

DNA damage response (DDR) deficiencies result in genome instability, which is one of the hallmarks of cancer. Poly (ADP-ribose) polymerase (PARP) enzymes take part in various DDR pathways, determining cell fate in the wake of DNA damage. PARPs are readily druggable and PARP inhibitors (PARPi) against the main DDR-associated PARPs, PARP1 and PARP2, are currently approved for the treatment of a range of tumor types. Inhibition of efficient PARP1/2-dependent DDR is fatal for tumor cells with homologous recombination deficiencies (HRD), especially defects in breast cancer type 1 susceptibility protein 1 or 2 (BRCA1/2)-dependent pathway, while allowing healthy cells to survive. Moreover, PARPi indirectly influence the tumor microenvironment by increasing genomic instability, immune pathway activation and PD-L1 expression on cancer cells. For this reason, PARPi might enhance sensitivity to immune checkpoint inhibitors (ICIs), such as anti-PD-(L)1 or anti-CTLA4, providing a rationale for PARPi-ICI combination therapies. In this review, we discuss the complex background of the different roles of PARP1/2 in the cell and summarize the basics of how PARPi work from bench to bedside. Furthermore, we detail the early data of ongoing clinical trials indicating the synergistic effect of PARPi and ICIs. We also introduce the diagnostic tools for therapy development and discuss the future perspectives and limitations of this approach.

Pre-Existing and Acquired Resistance to PARP Inhibitor-Induced Synthetic Lethality

The advanced development of synthetic lethality has opened the doors for specific anti-cancer medications of personalized medicine and efficient therapies against cancers. One of the most popular approaches being investigated is targeting DNA repair pathways as the implementation of the PARP inhibitor (PARPi) into individual or combinational therapeutic schemes. Such treatment has been effectively employed against homologous recombination-defective solid tumors as well as hematopoietic malignancies. However, the resistance to PARPi has been observed in both preclinical research and clinical treatment. Therefore, elucidating the mechanisms responsible for the resistance to PARPi is pivotal for the further success of this intervention. Apart from mechanisms of acquired resistance, the bone marrow microenvironment provides a pre-existing mechanism to induce the inefficiency of PARPi in leukemic cells. Here, we describe the pre-existing and acquired mechanisms of the resistance to PARPi-induced synthetic lethality. We also discuss the potential rationales for developing effective therapies to prevent/repress the PARPi resistance in cancer cells.

Nuclear translocation of Gasdermin D sensitizes colorectal cancer to chemotherapy in a pyroptosis-independent manner

Gasdermin D (GSDMD) has recently been identified as a cytoplasmic effector protein that plays a central role in pyroptosis of immune cells. However, GSDMD is a universally expressed protein, and its function beyond pyroptosis, especially in cancer cells, has not been well characterized. Here, we report that predominant localization of GSDMD in the nucleoplasm in vivo indicates favorable clinical outcomes in colorectal cancer, while a lack of nuclear localization of GSDMD is associated with poor outcomes. Nuclear GSDMD, rather than cytoplasmic GSDMD, inhibits cell growth and promotes apoptosis in colorectal cancer. Hypoxia in the tumor microenvironment accounts for mild or moderate nuclear translocation of GSDMD in vivo. Under the stimulation of chemotherapy drugs, nuclear GSDMD promotes apoptosis via regulation of its subcellular distribution rather than pyroptosis-related cleavage. After nuclear translocation, GSDMD interacts with PARP-1 to dramatically inhibit its DNA damage repair-related function by functioning like the PARP inhibitor olaparib, thus forming a "hypoxia/chemotherapy-GSDMD nuclear translocation-PARP-1 blockade-DNA damage and apoptosis" axis. This study redefines the pyroptosis-independent function of GSDMD and suggests that the subcellular localization of GSDMD may serve as a molecular indicator of clinical outcomes and a promising therapeutic target in colorectal cancer.

Xanthorrhizol, a potential anticancer agent, from Curcuma xanthorrhiza Roxb

BACKGROUND

Xanthorrhizol (XTZ), a bisabolene sesquiterpenoid, is abundantly found in the plant Curcuma xanthorrhiza Roxb. Traditionally, C. xanthorrhiza is widely used for the treatment of different health conditions, including common fever, infection, lack of appetite, fatigue, liver complaints, and gastrointestinal disorders. XTZ exhibits wide-ranging pharmacological activities, including anticancer, antioxidative, anti-inflammatory, antimicrobial, and antidiabetic activities, in addition to a protective effect on multiple organs. The present review provides detailed findings on the anticancer activities of XTZ and the underlying cellular and molecular mechanisms.

METHODS

Literature was searched systematically in main databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, with keywords "tumor AND xanthorrhizol" or "cancer AND xanthorrhizol".

RESULTS

Studies show that XTZ has preventive and therapeutic activities against different types of cancer, including breast, cervical, colon, liver, lung, oral and esophageal, and skin cancers. XTZ regulates multiple signaling pathways that block carcinogenesis and proliferation. In vitro and in vivo studies showed that XTZ targets different kinases, inflammatory cytokines, apoptosis proteins, and transcription factors, leading to the suppression of angiogenesis, metastasis, and the activation of apoptosis and cell cycle arrest.

CONCLUSION

The potential anticancer benefits of XTZ recommend further in vivo studies against different types of cancer. Further, XTZ needs to be confirmed for its toxicity, bioavailability, protective, antifatigue, and energy booster activities. Future studies for the therapeutic development of XTZ may be directed to cancer-related fatigue.

Bioactive NAD+ Regeneration Promoted by Multimetallic Nanoparticles Based on Graphene-Polymer Nanolayers

The concentration of nicotinamide adenine dinucleotide oxidized form (NAD⁺) changes during aging, and the production of NAD⁺ can significantly affect both health span and life span. However, it is still of great challenge to regenerate NAD⁺ from its precursors. Herein, we introduce a method to prepare multimetallic nanoparticles (including Au, Pt, Cu, and MgO) that can efficiently promote the conversion of NADH to NAD⁺. The nanoparticles are made by mixing reduced graphene oxide-polyethyleneimine-polyacrylic acid nano-films with metallic salts, where four different metal ions are reduced and grow at the surface of the nanolayers. The morphology, size, and growth rate of nanoparticles can be controlled by adding surfactants, applying an electric field, and so forth. Our multimetallic nanoparticles exhibit excellent catalytic performance that a complete conversion of NADH to NAD⁺ can be finished in 3 min without introducing additional oxygen. This work presents a way for the preparation of multimetallic nanoparticles to promote NAD⁺ regeneration, which shows great promise for the future design of high-performance materials for antiaging.

Adapalene and Doxorubicin Synergistically Promote Apoptosis of TNBC Cells by Hyperactivation of the ERK1/2 Pathway Through ROS Induction

Doxorubicin is a commonly used chemotherapeutic agent to treat several malignancies, including aggressive tumors like triple-negative breast cancer. It has a limited therapeutic index owing to its extreme toxicity and the emergence of drug resistance. As a result, there is a pressing need to find innovative drugs that enhance the effectiveness of doxorubicin while minimizing its toxicity. The rationale of the present study is that combining emerging treatment agents or repurposed pharmaceuticals with doxorubicin might increase susceptibility to therapeutics and the subsequent establishment of improved pharmacological combinations for treating triple-negative breast cancer. Additionally, combined treatment will facilitate dosage reduction, reducing the toxicity associated with doxorubicin. Recently, the third-generation retinoid adapalene was reported as an effective anticancer agent in several malignancies. This study aimed to determine the anticancer activity of adapalene in TNBC cells and its effectiveness in combination with doxorubicin, and the mechanistic pathways in inhibiting tumorigenicity. Adapalene inhibits tumor cell growth and proliferation and acts synergistically with doxorubicin in inhibiting growth, colony formation, and migration of TNBC cells. Also, the combination of adapalene and doxorubicin enhanced the accumulation of reactive oxygen species triggering hyperphosphorylation of Erk1/2 and caspase-dependent apoptosis. Our results demonstrate that adapalene is a promising antitumor agent that may be used as a single agent or combined with present therapeutic regimens for TNBC treatment.

The Role of PARP ‐1 and NF‐κB in Bile‐Induced DNA Damage and Oncogenic Profile in Hypopharyngeal Cells

OBJECTIVES/HYPOTHESIS

We recently documented that acidic bile, a gastroesophageal reflux content, can cause invasive hypopharyngeal squamous cell carcinoma, by inducing widespread DNA damage and promoting nuclear factor kappa B (NF-κB)-related oncogenic molecular events. Poly or adenosine diphosphate (ADP)-ribose polymerase-1 (PARP-1), a sensitive sensor of DNA damage, may interact with NF-κB. We hypothesized that PARP-1 is activated in hypopharyngeal cells (HCs) with marked DNA damage caused by acidic bile, hence there is an association between PARP-1 and NF-κB activation or its related oncogenic profile, in this process.

STUDY DESIGN

In vitro study.

METHODS

We targeted PARP-1 and NF-κB(p65), using pharmacologic inhibitors, 1.0 μM Rucaparib (AG014699) and 10 μM BAY 11-7082 {3-[4=methylphenyl)sulfonyl]-(2E)-propenenitrile}, respectively, or silencing their gene expression (siRNAs) and used immunofluorescence, luciferase, cell viability, direct enzyme-linked immunosorbent assays, and qPCR analysis to detect the effect of targeting PARP-1 or NF-κB in acidic bile-induced DNA damage, PARP-1, p-NF-κB, and B-cell lymphoma 2 (Bcl-2) expression, as well as NF-κB transcriptional activity, cell survival, and mRNA oncogenic phenotype in HCs.

RESULTS

We showed that (i) PARP-1 is overexpressed by acidic bile, (ii) targeting NF-κB adequately prevents the acidic bile-induced DNA double-strand breaks (DSBs) by gamma H2A histone family member X (γH2AX), oxidative DNA/RNA damage, PARP-1 overexpression, anti-apoptotic mRNA phenotype, and cell survival, whereas (iii) targeting PARP-1 preserves elevated DNA damage, NF-κB activation, and anti-apoptotic phenotype.

CONCLUSION

We document for the first time that the activation of PARP-1 is an early event during bile reflux-related head and neck carcinogenesis and that NF-κB can mediate DNA damage and PARP-1 activation. Our data encourage further investigation into how acidic bile-induced activated NF-κB mediates DNA damage in hypopharyngeal carcinogenesis.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:1146-1155, 2023.

Centella asiatica Modulates Nrf-2 Antioxidant Mechanisms and Enhances Reactive Oxygen Species-Mediated Apoptotic Cell Death in Leukemic (THP-1) Cells

Centella asiatica is commonly used in traditional medicine owing to its many therapeutic properties including but not limited to antioxidant and antitumor potential. This study examined the antioxidant and antiproliferative effects of its crude (C) and fractionated (C3) ethanolic leaf extracts in THP-1 cells. In THP-1 cells, C and C3 cytotoxicity was evaluated (WST-1 viability assay; 24 h; [0.2-3 mg/mL]) and half maximal inhibitory concentration was obtained. Malondialdehyde (MDA; spectrophotometry), mitochondrial depolarization (Δψ_m), intracellular reactive oxygen species (IROS; flow cytometry), glutathione (GSH), oxidized GSH (GSSG) concentrations, adenosine triphosphate (ATP) levels, caspase activities (luminometry) and DNA fragmentation (single cell gel electrophoresis assay) were evaluated. Protein expression and gene expression was quantified by Western blotting and quantitative polymerase chain reaction, respectively. THP-1 cell viability was dose-dependently reduced by C and C3. MDA, IROS, GSH, and Δψ_m were increased and ATP was decreased by C and C3 (P < .01). Antioxidant gene expression, Nrf-2 protein expression, and GSSG levels (P < .01) were increased by C, but were decreased by C3. C and C3 elevated caspase activity and DNA damage (P < .0001), whereas they decreased glutathione peroxidase and Bcl-2 protein expressions (P < .003). c-PARP protein expression and c-myc gene expression was decreased by C, whereas they were increased by C3 (P < .002). C3 reduced OGG-1 gene expression (P < .0003). Antioxidant responses were increased by C, whereas they were decreased by C3. Both C and C3 exerted antiproliferative effects in THP-1 cells by enhancing apoptosis. Of note, C3 more effectively induced apoptosis.

A small-molecule Skp1 inhibitor elicits cell death by p53-dependent mechanism

Skp1 overexpression promotes tumor growth, whereas reduced Skp1 activity is also linked with genomic instability and neoplastic transformation. This highlights the need to gain better understanding of Skp1 biology in cancer settings. To this context, potent and cellularly active small-molecule Skp1 inhibitors may be of great value. Using a hypothesis-driven, structure-guided approach, we herein identify Z0933M as a potent Skp1 inhibitor with K_D ∼0.054 μM. Z0933M occupies a hydrophobic hotspot (P1) – encompassing an aromatic cage of two phenylalanines (F101 and F139) – alongside C-terminal extension of Skp1 and, thus, hampers its ability to interact with F-box proteins, a prerequisite step to constitute intact and active SCF E3 ligase(s) complexes. In cellulo, Z0933M disrupted SCF E3 ligase(s) functioning, recapitulated previously reported effects of Skp1-reduced activity, and elicited cell death by a p53-dependent mechanism. We propose Z0933M as valuable tool for future efforts toward probing Skp1 cancer biology, with implications for cancer therapy.

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Z0933M manifests strong binding with Skp1 and inhibits Skp1-F-box PPIs

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Z0933M interacts with a P1 hotspot alongside C-terminal extension of Skp1

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Z0933M alters SCF E3 ligase functioning, leading to substrate accumulation/modulation

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Z0933M causes cell-cycle arrest, and elicits cell death by p53-dependent mechanism

Anticancer Activity of Natural and Semi-Synthetic Drimane and Coloratane Sesquiterpenoids

Drimane and coloratane sesquiterpenoids are present in several plants, microorganisms, and marine life. Because of their cytotoxic activity, these sesquiterpenoids have received increasing attention as a source for new anticancer drugs and pharmacophores. Natural drimanes and coloratanes, as well as their semi-synthetic derivatives, showed promising results against cancer cell lines with in vitro activities in the low micro- and nanomolar range. Despite their high potential as novel anticancer agents, the mode of action and structure–activity relationships of drimanes and coloratanes have not been completely enlightened nor systematically reviewed. Our review aims to give an overview of known structures and derivatizations of this class of sesquiterpenoids, as well as their activity against cancer cells and potential modes-of-action. The cytotoxic activities of about 40 natural and 25 semi-synthetic drimanes and coloratanes are discussed. In addition to that, we give a summary about the clinical significance of drimane and coloratane sesquiterpenoids.

Urokinase Receptor uPAR Downregulation in Neuroblastoma Leads to Dormancy, Chemoresistance and Metastasis

Simple Summary

uPAR is a membrane receptor that contributes to extracellular matrix remodeling and controls cellular adhesion, proliferation, survival, and migration. We demonstrate that the initially high uPAR expression predicts poor survival in neuroblastoma. However, relapsed neuroblastomas have a significantly decreased uPAR expression. uPAR downregulation in neuroblastoma cells leads to dormancy and resistance to chemotherapeutic drugs. In mice, low uPAR-expressing neuroblastoma cells formed smaller primary tumors but more frequent metastasis.

Abstract

uPAR is a membrane receptor that binds extracellular protease urokinase, contributes to matrix remodeling and plays a crucial role in cellular adhesion, proliferation, survival, and migration. uPAR overexpression in tumor cells promotes mitogenesis, opening a prospective avenue for targeted therapy. However, uPAR targeting in cancer has potential risks. We have recently shown that uPAR downregulation in neuroblastoma promotes epithelial-mesenchymal transition (EMT), potentially associated with metastasis and chemoresistance. We used data mining to evaluate the role of uPAR expression in primary and relapsed human neuroblastomas. To model the decreased uPAR expression, we targeted uPAR using CRISPR/Cas9 and shRNA in neuroblastoma Neuro2a cells and evaluated their chemosensitivity in vitro as well as tumor growth and metastasis in vivo. We demonstrate that the initially high PLAUR expression predicts poor survival in human neuroblastoma. However, relapsed neuroblastomas have a significantly decreased PLAUR expression. uPAR targeting in neuroblastoma Neuro2a cells leads to p38 activation and an increased p21 expression (suggesting a dormant phenotype). The dormancy in neuroblastoma cells can be triggered by the disruption of uPAR-integrin interaction. uPAR-deficient cells are less sensitive to cisplatin and doxorubicin treatment and exhibit lower p53 activation. Finally, low uPAR-expressing Neuro2a cells formed smaller primary tumors, but more frequent metastasis in mice. To the best of our knowledge, this is the first study revealing the pathological role of dormant uPAR-deficient cancer cells having a chemoresistant and motile phenotype.

Pleiotropic role of PARP1: an overview

Poly (ADP-ribose) polymerase 1 (PARP1) protein is encoded by the PARP1 gene located on chromosome 1 (1q42.12) in human cells. It plays a crucial role in post-translational modification by adding poly (ADP-ribose) (PAR) groups to various proteins and PARP1 itself by utilizing nicotinamide adenine dinucleotide (NAD +) as a substrate. Since the discovery of PARP1, its role in DNA repair and cell death has been its identity. This is evident from an overwhelmingly high number of scientific reports in this regard. However, PARP1 also plays critical roles in inflammation, metabolism, tumor development and progression, chromatin modification and transcription, mRNA stability, and alternative splicing. In the present study, we attempted to compile all the scattered scientific information about this molecule, including the structure and multifunctional role of PARP1 in cancer and non-cancer diseases, along with PARP1 inhibitors (PARPis). Furthermore, for the first time, we have classified PARP1-mediated cell death for ease of understanding its role in cell death pathways.

RNF166 plays a dual role for Lys63-linked ubiquitination and sumoylation of its target proteins

Ubiquitination and sumoylation are two important posttranslational modifications in cells. RING (Really Interesting New Gene)-type E3 ligases play essential roles in regulating a plethora of biological processes such as cell survival and death. In our previous study, we performed a microarray using inputs from MN9D dopaminergic neuronal cells treated with 6-hydroxydopamine and identified a novel RING-type E3 ligase, RNF166. We showed that RNF166 exerts proapoptotic effects via ubiquitin-dependent degradation of X-linked inhibitor of apoptosis and subsequent overactivation of caspase-dependent neuronal death following 6-hydroxydopamine treatment. In the present study, we further expanded the list of RNF166's binding substrates using mass spectral analyses of immunoprecipitates obtained from RNF166-overexpressing HEK293 cells. Poly (ADP-ribose) polymerase 1, ATPase WRNIP1, X-ray repair cross-complementing protein 5 (Ku80), and replication protein A 70 were identified as potential binding partners of RNF166. Additionally, we confirmed that RNF166 interacts with and forms lysine 63-linked polyubiquitin chains in Ku80. Consequently, these events promoted the increased stability of Ku80. Intriguingly, we found that RNF166 also contains distinct consensus sequences termed SUMO-interacting motifs and interacts with apoptosis signal-regulating kinase 1 (ASK1). We determined that RNF166 induces the sumoylation of ASK1. Overall, our data provide novel evidence that RNF166 has a dual function of Lys63-linked ubiquitination and sumoylation of its cellular targets.

Overactive EGF signaling suppresses a C. elegans pnc-1 egg-laying phenotype independent of known signaling mediators

Nicotinamide recycling is critical to the development and function of Caenorhabditis elegans. Excess nicotinamide in a pnc-1 nicotinamidase mutant causes the necrosis of uv1 and OLQ cells and a highly penetrant egg laying defect. An EGF receptor (let-23) gain-of-function mutation suppresses the Egl phenotype in pnc-1 animals. However, gain-of-function mutations in either of the known downstream mediators, let-60/ Ras or itr-1, are not sufficient. Phosphatidylcholine synthesis is neither required nor sufficient, in contrast to its role in the let-23gf rescue of uv1 necrosis. The mechanism behind the let-23gf suppression of the pnc-1 Egl phenotype is unknown.

Detection of BRCA1/2 Mutation and Analysis of Clinicopathological Characteristics in 141 Cases of Ovarian Cancer

Breast cancer susceptibility genes 1 and 2 (BRCA1 and BRCA2) are known biomarkers for hereditary ovarian cancer (OC). However, a comprehensive association study between BRCA1/2 mutation spectrum and clinicopathological characteristics in Chinese ovarian cancer patients has not been performed yet to our best knowledge. To fill in this gap, we collected BRCA1/2 sequencing data and clinical information of 141 OC patients from Fujian Cancer Hospital between April 2018 and March 2020. The clinical information includes the age of onset, FIGO staging, pathological types, serum 125 detection level, lymph node metastasis, distant metastasis, the expression of Ki67, and disease history of the patient and his/her family. We then studied their associations by software SciPy 1.0. As a result, we detected pathogenic and potentially pathogenic BRCA1/2 mutations in 27 out of 141 patients (19.15%). Among the 27 patients with mutations, the major type of mutation was frameshift, which was observed in 12 patients (44.4%). Most of the mutation sites were distributed on exons 10 and 11, accounting for 48.1% (13/27) and 22.2% (6/27), respectively. In terms of histological classification, high-grade serous adenocarcinoma accounted for 79.43% of the 141 samples. The BRCA1/2 mutation group was all high-grade serous adenocarcinoma, accounting for 24.1% (27/112) of this group. The incidence of pathogenic mutation in BRCA1 and BRCA2 was 15.7% (19/112) and 7.27% (8/112), respectively. Univariate analysis showed that there was no significant difference between patients with BRCA1/2 mutation and others in age-of-onset, FIGO stage, pathological types, serum CA125 level, lymph node metastasis, the expression of Ki67, and personal and family disease history. However, there are significant differences between patients with BRCA1/2 mutation and others in distant metastasis rate (P < 0.002). In addition, the BRCA1/2 mutation rate in 141 ovarian cancer patients was similar to those reported in other studies in China. Nearly one-quarter of high-grade serous carcinomas had BRCA1/2 mutations. In conclusion, our study indicated that patients with BRCA1/2 mutations were more likely to undergo distant metastasis, and BRCA1/2 mutation detection should be performed for patients with high-grade serous adenocarcinoma to guide the selection of clinical treatment options.

Suppression of isoprenylcysteine carboxylmethyltransferase compromises DNA damage repair

Inhibition of isoprenylcysteine carboxylmethyltransferase reduces cancer cells’ ability to repair DNA damage by suppressing the expression of critical DNA damage repair pathway genes, hence increasing their vulnerability to DNA damaging insults such as PARP inhibitors and other DNA damage agents.

DNA damage is a double-edged sword for cancer cells. On the one hand, DNA damage–induced genomic instability contributes to cancer development; on the other hand, accumulating damage compromises proliferation and survival of cancer cells. Understanding the key regulators of DNA damage repair machinery would benefit the development of cancer therapies that induce DNA damage and apoptosis. In this study, we found that isoprenylcysteine carboxylmethyltransferase (ICMT), a posttranslational modification enzyme, plays an important role in DNA damage repair. We found that ICMT suppression consistently reduces the activity of MAPK signaling, which compromises the expression of key proteins in the DNA damage repair machinery. The ensuing accumulation of DNA damage leads to cell cycle arrest and apoptosis in multiple breast cancer cells. Interestingly, these observations are more pronounced in cells grown under anchorage-independent conditions or grown in vivo. Consistent with the negative impact on DNA repair, ICMT inhibition transforms the cancer cells into a “BRCA-like” state, hence sensitizing cancer cells to the treatment of PARP inhibitor and other DNA damage–inducing agents.

Resveratrol and Quercetin Potentiate the Cell Protection and Rescue Effects of NAD+ Precursors in HEK293 Cells Challenged by DNA Damaging Agent, N-Methyl-N′-nitro-N-nitrosoguanidine

DNA damage plays an essential role in the human ageing process. Recently, accumulating evidence has demonstrated that a decreased level of nicotinamide adenine dinucleotide (NAD+) is involved in human ageing and suggested that the natural supplements of NAD+ precursors and its homeostasis regulators might serve as a promising modality to slow down the human ageing process. In the present study, we analyzed the combinational effects and potential mechanism of NAD+ precursors, nicotinic acid (NA) and nicotinamide (NM), and the NAD+’ homeostasis regulators, resveratrol (R), and quercetin (Q) in the protection and rescue of HEK293 cells from N-methyl- N'-nitro- N nitrosoguanidine (MNNG)-induced DNA damage. The results indicate that resveratrol and quercetin can significantly potentiate the cell protection and rescue effects of NAD+ precursors in HEK293 cells attacked by the DNA damaging agent, MNNG. Intracellular NAD+ homeostasis and the PARP1 activation status are the key factors in determining the fate of the cells under DNA damaging stress.

Cytocidal Antitumor Effects against Human Ovarian Cancer Cells Induced by B-Lactam Steroid Alkylators with Targeted Activity against Poly (ADP-Ribose) Polymerase (PARP) Enzymes in a Cell-Free Assay

We evaluated three newly synthesized B-lactam hybrid homo-aza-steroidal alkylators (ASA-A, ASA-B and ASA-C) for their PARP1/2 inhibition activity and their DNA damaging effect against human ovarian carcinoma cells. These agents are conjugated with an alkylating component (POPA), which also served as a reference molecule (positive control), and were tested against four human ovarian cell lines in vitro (UWB1.289 + BRCA1, UWB1.289, SKOV-3 and OVCAR-3). The studied compounds were thereafter compared to 3-AB, a known PARP inhibitor, as well as to Olaparib, a standard third-generation PARP inhibitor, on a PARP assay investigating their inhibitory potential. Finally, a PARP1 and PARP2 mRNA expression analysis by qRT-PCR was produced in order to measure the absolute and the relative gene expression (in mRNA transcripts) between treated and untreated cells. All the investigated hybrid steroid alkylators and POPA decreased in vitro cell growth differentially, according to the sensitivity and different gene characteristics of each cell line, while ASA-A and ASA-B presented the most significant anticancer activity. Both these compounds induced PARP1/2 enzyme inhibition, DNA damage (alkylation) and upregulation of PARP mRNA expression, for all tested cell lines. However, ASA-C underperformed on average in the above tasks, while the compound ASA-B induced synthetic lethality effects on the ovarian cancer cells. Nevertheless, the overall outcome, leading to a drug-like potential, provides strong evidence toward further evaluation.

NAD+ Precursors and Antioxidants for the Treatment of Amyotrophic Lateral Sclerosis

Charcot first described amyotrophic lateral sclerosis (ALS) between 1865 and 1874 as a sporadic adult disease resulting from the idiopathic progressive degeneration of the motor neuronal system, resulting in rapid, progressive, and generalized muscle weakness and atrophy. There is no cure for ALS and no proven therapy to prevent it or reverse its course. There are two drugs specifically approved for the treatment of ALS, riluzol and edaravone, and many others have already been tested or are following clinical trials. However, at the present moment, we still cannot glimpse a true breakthrough in the treatment of this devastating disease. Nevertheless, our understanding of the pathophysiology of ALS is constantly growing. Based on this background, we know that oxidative stress, alterations in the NAD+-dependent metabolism and redox status, and abnormal mitochondrial dynamics and function in the motor neurons are at the core of the problem. Thus, different antioxidant molecules or NAD+ generators have been proposed for the therapy of ALS. This review analyzes these options not only in light of their use as individual molecules, but with special emphasis on their potential association, and even as part of broader combined multi-therapies.

Risks and rewards of targeting NAD+ homeostasis in the brain

Strategies to correct declining nicotinamide adenine dinucleotide (NAD⁺) levels in neurological disease and biological ageing are promising therapeutic candidates. These strategies include supplementing with NAD⁺ precursors, small molecule activation of NAD⁺ biosynthetic enzymes, and treatment with small molecule inhibitors of NAD⁺ consuming enzymes such as CD38, SARM1 or members of the PARP family. While these strategies have shown efficacy in animal models of neurological disease, each of these has the mechanistic potential for adverse events that could preclude their preclinical use. Here, we discuss the implications of these strategies for treating neurological diseases, including potential off-target effects that may be unique to the brain.

Hydrogen peroxide toxicity on auditory cells: An in vitro study

In recent decades, interest has increased in the role of reactive oxygen species (ROS) in health and disease. The ROS are key causative factors in several hearing loss pathologies including ototoxicity, noise trauma, cochlear ageing and ischemic injury. In order to investigate ROS effects on inner ear cells and counteract them, we developed an in vitro model of oxidative stress by exposing the inner ear cell line OC-k3 to hydrogen peroxide (H₂O₂) at concentrations able to affect in vivo cellular components but allowing cell survival. The treatment with high concentrations (20 and 30 μM) resulted in reduction of cell viability, activation of apoptosis/necrosis and alteration of morphology, cell cycle progression and antioxidant defences. The ROS effects in inner ear cells are difficult to assess in vivo. Organocultures may provide preservation of tissue architecture but involve ethical issues and can be used only for a limited time. An in vitro model that could be commercially available and easy to handle is necessary to investigate inner ear oxidative stress and the ways to counteract it. The OC-k3 line is a suitable in vitro model to study ROS effects on inner ear cells because the observed cell alterations and damages were similar to those reported in studies investigating ROS effects of ototoxic drugs, noise trauma and cochlear ageing.

Nicotinamide riboside attenuates age-associated metabolic and functional changes in hematopoietic stem cells

With age, hematopoietic stem cells (HSC) undergo changes in function, including reduced regenerative potential and loss of quiescence, which is accompanied by a significant expansion of the stem cell pool that can lead to haematological disorders. Elevated metabolic activity has been implicated in driving the HSC ageing phenotype. Here we show that nicotinamide riboside (NR), a form of vitamin B3, restores youthful metabolic capacity by modifying mitochondrial function in multiple ways including reduced expression of nuclear encoded metabolic pathway genes, damping of mitochondrial stress and a decrease in mitochondrial mass and network-size. Metabolic restoration is dependent on continuous NR supplementation and accompanied by a shift of the aged transcriptome towards the young HSC state, more youthful bone marrow cellular composition and an improved regenerative capacity in a transplant setting. Consequently, NR administration could support healthy ageing by re-establishing a more youthful hematopoietic system.

Aging affects circadian clock and metabolism and modulates timing of medication

Aging is associated with impairments in the circadian rhythms, and with energy deregulation that affects multiple metabolic pathways. The goal of this study is to unravel the complex interactions among aging, metabolism, and the circadian clock. We seek to identify key factors that inform the liver circadian clock of cellular energy status and to reveal the mechanisms by which variations in food intake may disrupt the clock. To address these questions, we develop a comprehensive mathematical model that represents the circadian pathway in the mouse liver, together with the insulin/IGF-1 pathway, mTORC1, AMPK, NAD+, and the NAD+ -consuming factor SIRT1. The model is age-specific and can simulate the liver of a young mouse or an aged mouse. Simulation results suggest that the reduced NAD+ and SIRT1 bioavailability may explain the shortened circadian period in aged rodents. Importantly, the model identifies the dosing schedules for maximizing the efficacy of anti-aging medications.

Regulation of cardiomyocyte DNA damage and cell death by the type 2A protein phosphatase regulatory protein alpha4

The type 2A protein phosphatase regulatory protein alpha4 (α4) constitutes an anti-apoptotic protein in non-cardiac tissue, however it’s anti-apoptotic properties in the heart are poorly defined. To this end, we knocked down α4 protein expression (α4 KD) using siRNA in cultured H9c2 cardiomyocytes and confirmed the lack of DNA damage/cell death by TUNEL staining and MTT assay. However, α4 KD did increase the phosphorylation of p53 and ATM/ATR substrates, decreased the expression of poly ADP-ribose polymerase and associated fragments. Expression of anti-apoptotic proteins Bcl-2 and Bcl-xL was reduced, whereas expression of pro-apoptotic BAX protein did not change. Alpha4 KD reduced basal H2AX Ser139 phosphorylation, whereas adenoviral-mediated re-expression of α4 protein following α4 KD, restored basal H2AX phosphorylation at Ser139. The sensitivity of H9c2 cardiomyocytes to doxorubicin-induced DNA damage and cytotoxicity was augmented by α4 KD. Adenoviral-mediated overexpression of α4 protein in ARVM increased PP2AC expression and augmented H2AX Ser139 phosphorylation in response to doxorubicin. Furthermore, pressure overload-induced heart failure was associated with reduced α4 protein expression, increased ATM/ATR protein kinase activity, increased H2AX expression and Ser139 phosphorylation. Hence, this study describes the significance of altered α4 protein expression in the regulation of DNA damage, cardiomyocyte cell death and heart failure.

Shikonin inhibits proliferation of melanoma cells by MAPK pathway-mediated induction of apoptosis

Shikonin, a natural product isolated from the roots of Lithospermum erythrorhizon, exhibits pharmacological effects against inflammation, ulcers, infections, and tumors. In the present study, we aimed to investigate the antitumor effects of shikonin on the human melanoma cell line, A375SM, and in an in vivo mouse xenograft model. We examined the anticancer effects of shikonin by in vitro experiments (MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, 4′,6-diamidino-2-phenylindole (DAPI) stain, annexin V/ propidium iodide (PI) stain, and protein analysis of apoptosis and mitogen-activated protein kinase (MAPK) pathways). Further, the anticancer effect in vivo was confirmed through a xenograft model. Our results showed that shikonin inhibited the proliferation of melanoma cells in a dose-dependent manner. In addition, shikonin significantly increased nucleus and chromatin condensation and early/late apoptosis. Shikonin also increased the pro-apoptotic proteins and decreased the anti-apoptotic proteins. Additionally, shikonin was overexpressed in MAPK pathways. Investigation of the effects of shikonin in a mouse xenograft model not only showed decreased A375SM tumor volume but also increased apoptosis as determined by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Furthermore, pathologic changes were not observed in the liver and kidney of mice. Collectively, the study indicated that shikonin inhibited the proliferation of the human melanoma cells by inducing apoptosis, mediated by MAPK pathway and that it is a potential candidate for an anticancer drug against melanoma cancer.

Approaches to treat pulmonary arterial hypertension by targeting bmpr2 - from cell membrane to nucleus

Pulmonary arterial hypertension (PAH) is estimated to affect between 10-50 people per million worldwide. The lack of cure and devastating nature of the disease means that treatment is crucial to arrest rapid clinical worsening. Current therapies are limited by their focus on inhibiting residual vasoconstriction rather than targeting key regulators of the cellular pathology. Potential disease-modifying therapies may come from research directed towards causal pathways involved in the cellular and molecular mechanisms of disease. It is widely acknowledged, that targeting reduced expression of the critical bone morphogenetic protein type-2 receptor (BMPR2) and its associated signalling pathways is a compelling therapeutic avenue to explore. In this review we highlight the advances that have been made in understanding this pathway and the therapeutics that are being tested in clinical trials and the clinic to treat PAH.

PARP-1 induces EMT in non-small cell lung carcinoma cells via modulating the transcription factors Smad4, p65 and ZEB1

AIM

To study the role of PARP-1 in EMT of non-small cell lung carcinoma.

MATERIALS AND METHODS

We used H1299 and H460 lung cancer cells for knockdown study of PARP-1 using shPARP-1 lentiviral particle. We performed western blotting, confocal microscopy, semi-quantitative PCR, wound healing and colony formation assays.

BACKGROUND AND KEY FINDINGS

PARP-1 (poly-ADP ribose polymerase-1) is a multi-domain protein having DNA binding, auto-modification and catalytic domain, that participates in many biological processes including DNA damage detection and repair, transcription regulation, apoptosis, necrosis, cancer progression and metastasis. Metastasis is a leading cause of death in cancer patients, which starts in epithelial tumors via initiating epithelial to mesenchymal transition. There are various transcription factors involved in EMT including Snail-1, Smads, p65, ZEB1 and Twist1. We studied the effect of PARP-1 knockdown on EMT in non-small cell lung cancer cell line H1299. We found a significant increase in epithelial marker including ZO1 and β-catenin, while prominent decrease in the mesenchymal marker vimentin after PARP-1 knockdown in H1299 cells. Transcription factors including p65, Smad4 and ZEB1 showed significant decrease with concurrent expression of EMT markers. Cell migration and colony formation decreased after PARP-1 knockdown in H1299 cells.

SIGNIFICANCE

Overall, the shRNA mediated knockdown of PARP-1 in H1299 cells resulted in reversal of EMT or mesenchymal to epithelial transition (MET) characterized by an increase in epithelial markers and a decrease in mesenchymal markers, via down-regulating transcription factors including Smad4, p65 and ZEB1. Thus PARP-1 has a role in EMT in lung cancer.

Trichothecene macrolides from the endophytic fungus Paramyrothecium roridum and their cytotoxic activity

The chemical investigation of the secondary metabolites of Paramyrothecium roridum (homotypic synonym: Myrothecium roridum), an endophytic fungus isolated from the medicinal plant Morinda officinalis, led to the isolation of twelve cytotoxic trichothecene macrolides, including two new ones, named myrothecines H and I. The structures of the new macrolides were elucidated by extensive spectroscopic measurements analyses. In addition, the cytotoxic activities of these compounds were evaluated against SF-268, NCI-H460, and HepG-2 tumor cell lines, and all isolated compounds (1-12) exhibited significant cytotoxic activity with the IC₅₀ ranging from 0.0002-16.2 μM. Moreover, the inhibitory activity of myrothecines H and I was evidenced by inducing phosphorylation of JNK (c-Jun N-terminal protein kinase) protein and the PARP (poly ADP-ribose polymerase) cleavage, and eventually induce apoptosis of HepG-2 cells. The results indicated that myrothecines H and I could be applied as chemotherapeutic agents.

Tumor treating fields (TTF) treatment enhances radiation-induced apoptosis in pancreatic cancer cells

PURPOSE

Tumor treating fields (TTF) therapy is a noninvasive method that uses alternating electric fields to treat various types of cancer. This study demonstrates the combined effect of TTF and radiotherapy (RT) in vitro on pancreatic cancer, which is known to be difficult to treat.

MATERIALS AND METHODS

In CFPAC-I and HPAF-II pancreatic cancer cell lines, the combined in vitro effect of TTF and RT was evaluated by measuring cell counts, markers of apoptosis, and clonogenic cell survival. The synergy effects were verified using the Valeriote and Carpentier equations.

RESULTS

TTF and RT inhibited cancer cell growth more effectively than did monotherapy with TTF or RT. The combined treatment also enhanced apoptosis more than monotherapy, as shown by assays for cleaved poly (ADP-ribose) polymerase (PARP) and annexin V. In addition, on the survival curve, this treatment method has been shown to work synergistically.

CONCLUSION

These results suggest that combined treatment with TTF and RT may be a good alternative treatment for patients with pancreatic cancer.

An assessment of poly (ADP-ribose) polymerase-1 role in normal and cancer cells

Poly (ADP-ribose) polymerase (PARP) is a superfamily of 18 proteins characterized by the PARP homology domain, the catalytic domain. This catalytic domain helps in the ADP-ribosylation of various acceptor proteins using nicotinamide adenine dinucleotide (NAD+) as a donor for ADP-ribose. PARP-1 and PARP-2 carry out 80% of poly-ADP-ribosylation of cellular protein. Hence, their combined knockout results in embryonic lethality of mice. PARP-1 consists of three major domains, namely, DNA binding domain, automodification domain, and a catalytic domain. These domains further consist of subdomains and motifs, which helps PARP-1 in a diverse function. PARP-1 is mainly involved in DNA damage detection and repair, but emerging evidence suggests its role in many other functions such as DNA synthesis, replication, apoptosis, necrosis, and cancer progression. Herein, we review the current state of the PARP-1 role in DNA damage repair and other biological processes including epithelial to mesenchymal transition (EMT). We have also observed the role of PARP-1 in modulating EMT regulators like E-cadherin, Vimentin, Claudin-1, Snail, Smad-4, Twist-1, and β-catenin. Here, we have also attempted to relate the role of PARP-1 in EMT of cancer cells.