Overexpression of ABCC1 and ABCG2 confers resistance to talazoparib, a poly (ADP-Ribose) polymerase inhibitor.

AIMS: The overexpression of ABC transporters on cancer cell membranes is one of the most common causes of multidrug resistance (MDR). This study investigates the impact of ABCC1 and ABCG2 on the resistance to talazoparib (BMN-673), a potent poly (ADP-ribose) polymerase (PARP) inhibitor, in ovarian cancer treatment. METHODS: The cell viability test was used to indicate the effect of talazoparib in different cell lines. Computational molecular docking analysis was conducted to simulate the interaction between talazoparib and ABCC1 or ABCG2. The mechanism of talazoparib resistance was investigated by constructing talazoparib-resistant subline A2780/T4 from A2780 through drug selection with gradually increasing talazoparib concentration. RESULTS: Talazoparib cytotoxicity decreased in drug-selected or gene-transfected cell lines overexpressing ABCC1 or ABCG2 but can be restored by ABCC1 or ABCG2 inhibitors. Talazoparib competitively inhibited substrate drug efflux activity of ABCC1 or ABCG2. Upregulated ABCC1 and ABCG2 protein expression on the plasma membrane of A2780/T4 cells enhances resistance to other substrate drugs, which could be overcome by the knockout of either gene. In vivo experiments confirmed the retention of drug-resistant characteristics in tumor xenograft mouse models. CONCLUSIONS: The therapeutic efficacy of talazoparib in cancer may be compromised by its susceptibility to MDR, which is attributed to its interactions with the ABCC1 or ABCG2 transporters. The overexpression of these transporters can potentially diminish the therapeutic impact of talazoparib in cancer treatment.

Computer aided drug discovery (CADD) of a thieno[2,3-d]pyrimidine derivative as a new EGFR inhibitor targeting the ribose pocket.

Depending on the pharmacophoric characteristics of EGFR inhibitors, a new thieno[2,3-d]pyrimidine derivative has been developed. Firstly, the potential inhibitory effect of the designed compound against EGFR has been proven by docking experiments that showed correct binding modes and excellent binding energies of -98.44 and -88.00 kcal/mol, against EGFR wild-type and mutant type, respectively. Furthermore, MD simulations studies confirmed the precise energetic, conformational, and dynamic alterations that occurred after binding to EGFR. The correct binding was also confirmed by essential dynamics studies. To further investigate the general drug-like properties of the developed candidate, in silico ADME and toxicity studies have also been carried out. The thieno[2,3-d]pyrimidine derivative was synthesized following the earlier promising findings. Fascinatingly, the synthesized compound (4) showed promising inhibitory effects against EGFRWT and EGFRT790M with IC50 values of 25.8 and 182.3 nM, respectively. Also, it exhibited anticancer potentialities against A549 and MCF-7cell lines with IC50 values of 13.06 and 20.13 µM, respectively. Interestingly, these strong activities were combined with selectivity indices of 2.8 and 1.8 against the two cancer cell lines, respectively. Further investigations indicated the ability of compound 4 to arrest the cancer cells' growth at the G2/M phase and to increase early and late apoptosis percentages from 2.52% and 2.80 to 17.99% and 16.72%, respectively. Additionally, it was observed that compound 4 markedly increased the levels of caspase-3 and caspase-9 by 4 and 3-fold compared to the control cells. Moreover, it up-regulated the level of BAX by 3-fold and down-regulated the level of Bcl-2 by 3-fold affording a BAX/Bcl-2 ratio of 9.Communicated by Ramaswamy H. Sarma.

GATA binding protein 6 regulates apoptosis in silkworms through interaction with poly (ADP-ribose) polymerase.

The GATA family of genes plays various roles in crucial biological processes, such as development, cell differentiation, and disease progression. However, the roles of GATA in insects have not been thoroughly explored. In this study, a genome-wide characterization of the GATA gene family in the silkworm, Bombyx mori, was conducted, revealing lineage-specific expression profiles. Notably, GATA6 is ubiquitously expressed across various developmental stages and tissues, with predominant expression in the midgut, ovaries, and Malpighian tubules. Overexpression of GATA6 inhibits cell growth and promotes apoptosis, whereas, in contrast, knockdown of PARP mitigates the apoptotic effects driven by GATA6 overexpression. Co-immunoprecipitation (co-IP) has demonstrated that GATA6 can interact with Poly (ADP-ribose) polymerase (PARP), suggesting that GATA6 may induce cell apoptosis by activating the enzyme's activity. These findings reveal a dynamic and regulatory relationship between GATA6 and PARP, suggesting a potential role for GATA6 as a key regulator in apoptosis through its interaction with PARP. This research deepens the understanding of the diverse roles of the GATA family in insects, shedding light on new avenues for studies in sericulture and pest management.

Developments in the chemistry and biology of 1,2,3-triazolyl-C-nucleosides.

In the last 50 years, nucleoside analogs have been introduced to drug therapy as antivirals for different types of cancer due to their interference in cellular proliferation. Among the first line of nucleoside treatment drugs, ribavirin (RBV) is a synthetic N-nucleoside with a 1,2,4-triazole moiety that acts as a broad-spectrum antiviral. It is on the World Health Organization (WHO) list of essential medicines. However, this important drug therapy causes several side effects due to its nonspecific mechanism of action. There is thus a need for a continuous study of its scaffold. A particular approach consists of connecting  d-ribose to the nitrogen-containing base with a C-C bond. It provides more stability against enzymatic action and a better pharmacologic profile. The coronavirus disease (COVID) pandemic has increased the need for more solutions for the treatment of viral infections. Among these solutions, remdesivir, the first C-nucleoside, has been approved by the Food and Drug Administration (FDA) for clinical use against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It drew attention to the study of the C-nucleoside scaffold. Different C-nucleoside patterns have been synthesized over the years. They show many important activities against viruses and cancer cell lines. 1,2,3-Triazolyl-C-nucleoside derivatives are a prolific and efficient subclass of RBV analogs close to the already-known RBV with a C-C bond modification. These compounds are often prepared by alkynylation of the  d-ribose ring followed by azide-alkyne cycloaddition. They are reported to be active against the Crimean-Congo hemorrhagic fever virus and several tumoral cell lines, showing promising biological potential. In this review, we explore such approaches to 1,2,3-triazolyl-C-nucleosides and their evolution over the years.

2-Deoxy-d-ribose induces ferroptosis in renal tubular epithelial cells via ubiquitin-proteasome system-mediated xCT protein degradation.

Ferroptosis is a novel form of cell death triggered by iron-dependent lipid peroxidation. Recent findings suggest that inhibiting system χc-induces ferroptosis by reducing intracellular cystine levels, and that ferroptosis in renal tubular epithelial cells (RTECs) contributes to acute kidney injury (AKI) and diabetic nephropathy. Moreover, 2-deoxy-d-ribose (dRib) has been shown to inhibit cystine uptake through xCT, the functional unit of system χc-, in ß-cells. This study aimed to investigate if dRib induces ferroptosis in RTECs and identify the underlying mechanisms. dRib treatment reduced cystine uptake and glutathione (GSH) content, and increased intracellular levels of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), lipid reactive oxygen species (ROS), and cell death in both NRK-52E cells and primary cultured RTECs. However, treatment with inhibitors of ferroptosis, such as deferoxamine (DFO), ferrostatin-1 (Fer-1), and liproxstatin-1 (Lip-1), counteracted the effects of dRib on GSH, MDA, 4-HNE, and lipid ROS levels, as well as cell death. Additionally, 2-mercaptoethanol (2-ME) treatment or xCT gene overexpression protected against dRib-induced changes. Moreover, transmission electron microscopy revealed dRib-induced mitochondrial shrinkage, decrease in cristae number, and outer membrane rupture. Furthermore, dRib treatment upregulated the expression of genes associated with ferroptosis, and downregulated xCT protein expression. The decrease in xCT protein caused by dRib was consistently observed even when treated with the protein synthesis inhibitor cycloheximide. However, treatment with the proteasome inhibitor MG132 reversed the dRib-induced decrease in xCT protein expression. Additionally, dRib increased xCT protein ubiquitination. Overall, dRib induces ferroptosis in RTECs by degrading xCT protein through ubiquitin-proteasome system (UPS), resulting in reduced intracellular cystine uptake. Therefore, targeting the regulation of system χc-through UPS could be a potential therapeutic approach for AKI and diabetic nephropathy.

An alginate-Based tube gel delivering 2-deoxy-D-ribose for stimulation of wound healing.

Developing multifunctional wound dressings capable of inducing rapid angiogenesis and with antibacterial activity would be attractive for diabetic and superficial wound healing. Hydrogels delivered from tubes have several desirable features -they are easy to apply, keep the wound moist, reduce the entry of microorganisms and avoid the need for painful dressing removal. Previously we reported that 2 deoxy-D-ribose (2dDR) delivered from a variety of dressings is capable of promoting wound healing by stimulating angiogenesis. Alginate hydrogels are an ideal vehicle to deliver a bioactive agent capable of promoting wound healing. In this study we developed and evaluated a tube hydrogel capable of delivering 2dDR with the aim of achieving a stable, convenient to administer and biologically effective wound treatment. Further, we included the stabilizer 2-phenoxy ethanol which provided antimicrobial activity. We synthesized hydrogels by the Green method, using simple mixing of sodium alginate, propylene glycol, 2-phenoxy ethanol and 2dDR in water. FTIR (Fourier transformation infrared spectroscopy) analysis confirmed an absence of undesirable chemical changes in the gel components, and SEM images of the freeze-dried gels showed porous structures. When 2dDR alginate gel (2dDR-SA hydrogel) was placed in PBS at 37°C, almost 92% of 2dDR was released within 7 days. When tested on cultured cells, 2dDR-SA hydrogels did not inhibit metabolic activity or proliferation, achieving up to 90 and 98% of control respectively over 7 days. 2dDR-SA hydrogel also showed anti-bacterial activity against E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, and MRSA which was attributable to the stabilizer 2-phenoxy ethanol in the hydrogel. Stimulation of angiogenesis in the chorioallantoic membrane assay by 2dDR-SA hydrogel was found to be significant compared to the blank-SA. Wound healing potential was studied in full-thickness wounds in rats where acceleration of wound healing was seen. H&E staining of the wound tissue showed an enhanced number of blood vessels and re-epithelization, and a reduced number of inflammatory cells in 2dDR-SA treated animals compared to blank-hydrogels while Masson's trichrome staining showed increased collagen deposition. In summary we describe a convenient to apply hydrogel which has promise for use in a range of superficial skin wounds including applications in chronic wound care.

Inherited Retinal Degeneration: Towards the Development of a Combination Therapy Targeting Histone Deacetylase, Poly (ADP-Ribose) Polymerase, and Calpain.

Inherited retinal degeneration (IRD) represents a diverse group of gene mutation-induced blinding diseases. In IRD, the loss of photoreceptors is often connected to excessive activation of histone-deacetylase (HDAC), poly-ADP-ribose-polymerase (PARP), and calpain-type proteases (calpain). Moreover, the inhibition of either HDACs, PARPs, or calpains has previously shown promise in preventing photoreceptor cell death, although the relationship between these enzyme groups remains unclear. To explore this further, organotypic retinal explant cultures derived from wild-type mice and rd1 mice as a model for IRD were treated with different combinations of inhibitors specific for HDAC, PARP, and calpain. The outcomes were assessed using in situ activity assays for HDAC, PARP, and calpain, immunostaining for activated calpain-2, and the TUNEL assay for cell death detection. We confirmed that inhibition of either HDAC, PARP, or calpain reduced rd1 mouse photoreceptor degeneration, with the HDAC inhibitor Vorinostat (SAHA) being most effective. Calpain activity was reduced by inhibition of both HDAC and PARP whereas PARP activity was only reduced by HDAC inhibition. Unexpectedly, combined treatment with either PARP and calpain inhibitors or HDAC and calpain inhibitors did not produce synergistic rescue of photoreceptors. Together, these results indicate that in rd1 photoreceptors, HDAC, PARP, and calpain are part of the same degenerative pathway and are activated in a sequence that begins with HDAC and ends with calpain.

Berberine Rescues D-Ribose-Induced Alzheimer's Pathology via Promoting Mitophagy.

Mitochondrial dysfunction is considered an early event of Alzheimer disease (AD). D-ribose is a natural monosaccharide that exists in cells, especially in mitochondria, and can lead to cognitive dysfunction. However, the reason for this is unclear. Berberine (BBR) is an isoquinoline alkaloid that can target mitochondria and has great prospect in the treatment of AD. The methylation of PINK1 reinforces the burden of Alzheimer's pathology. This study explores the role of BBR and D-ribose in the mitophagy and cognitive function of AD related to DNA methylation. APP/PS1 mice and N2a cells were treated with D-ribose, BBR, and mitophagy inhibitor Mdivi-1 to observe their effects on mitochondrial morphology, mitophagy, neuron histology, AD pathology, animal behavior, and PINK1 methylation. The results showed that D-ribose induced mitochondrial dysfunction, mitophagy damage, and cognitive impairment. However, BBR inhibition of PINK1 promoter methylation can reverse the above effects caused by D-ribose, improve mitochondrial function, and restore mitophagy through the PINK1-Parkin pathway, thus reducing cognitive deficits and the burden of AD pathology. This experiment puts a new light on the mechanism of action of D-ribose in cognitive impairment and reveals new insights in the use of BBR for AD treatment.

Identification of a Chemical Inhibitor with a Novel Scaffold Targeting Decaprenylphosphoryl-ß-D-Ribose Oxidase (DprE1).

BACKGROUND: Tuberculosis is the second leading cause of death from infectious diseases worldwide. Multidrug-resistant Mycobacterium tuberculosis is spreading throughout the world, creating a crisis. Hence, there is a need to develop anti-tuberculosis drugs with novel structures and versatile mechanisms of action. OBJECTIVE: In this study, we identified antimicrobial compounds with a novel skeleton that inhibits mycobacterium decaprenylphosphoryl-ß-D-ribose oxidase (DprE1). METHODS: A multi-step, in silico, structure-based drug screening identified potential DprE1 inhibitors from a library of 154,118 compounds. We experimentally verified the growth inhibitory effects of the eight selected candidate compounds against Mycobacterium smegmatis. Molecular dynamics simulations were performed to understand the mechanism of molecular interactions between DprE1 and ompound 4. RESULTS: Eight compounds were selected through in silico screening. Compound 4 showed strong growth inhibition against M. smegmatis. Molecular dynamics simulation (50 ns) predicted direct and stable binding of Compound 4 to the active site of DprE1. CONCLUSION: The structural analysis of the novel scaffold in Compound 4 can pave way for antituberculosis drug development and discovery.

Effects of d-ribose on human erythrocytes: Non-enzymatic glycation of hemoglobin, eryptosis, oxidative stress and energy metabolism.

d-Ribose is not only an important component of some biomacromolecules, but also an active pentose with strong reducibility and non-enzymatic glycation ability. Previous studies reported the diverse role of d-ribose in different cells. In this study, the effects of d-ribose on non-enzymatic glycation of hemoglobin (Hb), as well as eryptosis, oxidative stress and energy metabolism of erythrocytes were observed by molecular fluorescence spectrophotometry, multi-wavelength spectrophotometry, high-pressure liquid chromatography (HPLC), mass spectrometry (MS) and flow cytometer. The results showed that d-ribose had the strongest non-enzymatic glycation ability to Hb in vitro when compared with other monosaccharides, and could enter the erythrocytes in a concentration-dependent manner, which was not inhibited by the specific glucose transporter 1 (GLUT1) inhibitor WZB117. In addition, d-ribose incubation increased the HbA1c, hemolysis, eryptosis, and ROS level of erythrocytes significantly more than that of d-glucose, however, no changes were observed in the levels of ATP, NADPH, and other intermediate energy metabolites in d-ribose treatment. Therefore, the strong non-enzymatic glycation ability of d-ribose may play an important role in erythrocyte damage.

Combination of Antimalarial and CNS Drugs with Antineoplastic Agents in MCF-7 Breast and HT-29 Colon Cancer Cells: Biosafety Evaluation and Mechanism of Action.

Drug combination and drug repurposing are two strategies that allow to find novel oncological therapies, in a faster and more economical process. In our previous studies, we developed a novel model of drug combination using antineoplastic and different repurposed drugs. We demonstrated the combinations of doxorubicin (DOX) + artesunate, DOX + chloroquine, paclitaxel (PTX) + fluoxetine, PTX + fluphenazine, and PTX + benztropine induce significant cytotoxicity in Michigan Cancer Foundation-7 (MCF-7) breast cancer cells. Furthermore, it was found that 5-FU + thioridazine and 5-fluorouracil (5-FU) + sertraline can synergistically induce a reduction in the viability of human colorectal adenocarcinoma cell line (HT-29). In this study, we aim to (1) evaluate the biosafety profile of these drug combinations for non-tumoral cells and (2) determine their mechanism of action in cancer cells. To do so, human fetal lung fibroblast cells (MRC-5) fibroblast cells were incubated for 48 h with all drugs, alone and in combination in concentrations of 0.25, 0.5, 1, 2, and 4 times their half-maximal inhibitory concentration (IC50). Cell morphology and viability were evaluated. Next, we designed and constructed a cell microarray to perform immunohistochemistry studies for the evaluation of palmitoyl-protein thioesterase 1 (PPT1), Ki67, cleaved-poly (ADP-ribose) polymerase (cleaved-PARP), multidrug resistance-associated protein 2 (MRP2), P-glycoprotein (P-gp), and nuclear factor-kappa-B (NF-kB) p65 expression. We demonstrate that these combinations are cytotoxic for cancer cells and safe for non-tumoral cells at lower concentrations. Furthermore, it is also demonstrated that PPT1 may have an important role in the mechanism of action of these combinations, as demonstrated by their ability to decrease PPT1 expression. These results support the use of antimalarial and central nervous system (CNS) drugs in combination regimens with chemotherapeutic agents; nevertheless, additional studies are recommended to further explore their complete mechanisms of action.

The synthetic lethality of targeting cell cycle checkpoints and PARPs in cancer treatment.

Continuous cell division is a hallmark of cancer, and the underlying mechanism is tumor genomics instability. Cell cycle checkpoints are critical for enabling an orderly cell cycle and maintaining genome stability during cell division. Based on their distinct functions in cell cycle control, cell cycle checkpoints are classified into two groups: DNA damage checkpoints and DNA replication stress checkpoints. The DNA damage checkpoints (ATM-CHK2-p53) primarily monitor genetic errors and arrest cell cycle progression to facilitate DNA repair. Unfortunately, genes involved in DNA damage checkpoints are frequently mutated in human malignancies. In contrast, genes associated with DNA replication stress checkpoints (ATR-CHK1-WEE1) are rarely mutated in tumors, and cancer cells are highly dependent on these genes to prevent replication catastrophe and secure genome integrity. At present, poly (ADP-ribose) polymerase inhibitors (PARPi) operate through "synthetic lethality" mechanism with mutant DNA repair pathways genes in cancer cells. However, an increasing number of patients are acquiring PARP inhibitor resistance after prolonged treatment. Recent work suggests that a combination therapy of targeting cell cycle checkpoints and PARPs act synergistically to increase the number of DNA errors, compromise the DNA repair machinery, and disrupt the cell cycle, thereby increasing the death rate of cancer cells with DNA repair deficiency or PARP inhibitor resistance. We highlight a combinational strategy involving PARP inhibitors and inhibition of two major cell cycle checkpoint pathways, ATM-CHK2-TP53 and ATR-CHK1-WEE1. The biological functions, resistance mechanisms against PARP inhibitors, advances in preclinical research, and clinical trials are also reviewed.

Pre-glycation impairs gelation of high concentration collagen solutions.

There remains a need for stiffer collagen hydrogels for tissue engineering and disease modeling applications. Pre-glycation, or glycation of collagen in solution prior to gelation, has been shown to increase the mechanics of collagen hydrogels while maintaining high viability of encapsulated cells. The stiffness of glycated collagen gels can be increased by increasing the collagen concentration, sugar concentration, and glycation time. However, previous studies on pre-glycation of collagen have used low collagen concentrations and/or low sugar concentrations and have not investigated the effect of glycation time. Therefore, the objective of this study was to determine the effects of pre-glycation with high sugar concentrations (up to 500 mM) and extended glycation times (up to 21 days) on high concentration collagen (8 mg/ml). The addition of sugar to the collagen and the formation of advanced glycation end products (AGEs) were quantified. The ability to gel successfully and rheological properties were determined and correlated with biochemical characterizations. Successful collagen gelation and rheological properties of pre-glycated collagen were found to be strongly dependent on the ratio of added sugars to added AGEs with high ratios impairing gelation and low ratios resulting in optimal storage moduli. There is likely a competing effect during pre-glycation of the formation of AGEs resulting in crosslinking of collagen and the formation of Amadori intermediates acting to increase collagen solubility. Overall, this study shows that collagen glycation can be optimized by increasing the formation of AGEs while maintaining a low ratio of added sugar to added AGEs.

Oligo-Fucoidan supplementation enhances the effect of Olaparib on preventing metastasis and recurrence of triple-negative breast cancer in mice.

BACKGROUND: Seaweed polysaccharides have been recommended as anticancer supplements and for boosting human health; however, their benefits in the treatment of triple-negative breast cancers (TNBCs) and improving immune surveillance remain unclear. Olaparib is a first-in-class poly (ADP-ribose) polymerase inhibitor. Oligo-Fucoidan, a low-molecular-weight sulfated polysaccharide purified from brown seaweed (Laminaria japonica), exhibits significant bioactivities that may aid in disease management. METHODS: Macrophage polarity, clonogenic assays, cancer stemness properties, cancer cell trajectory, glucose metabolism, the TNBC 4T1 cells and a 4T1 syngeneic mouse model were used to inspect the therapeutic effects of olaparib and Oligo-Fucoidan supplementation on TNBC aggressiveness and microenvironment. RESULTS: Olaparib treatment increased sub-G1 cell death and G2/M arrest in TNBC cells, and these effects were enhanced when Oligo-Fucoidan was added to treat the TNBC cells. The levels of Rad51 and programmed death-ligand 1 (PD-L1) and the activation of epidermal growth factor receptor (EGFR) and adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) facilitate drug resistance and TNBC metastasis. However, the combination of olaparib and Oligo-Fucoidan synergistically reduced Rad51 and PD-L1 levels, as well as the activity of EGFR and AMPK; consistently, TNBC cytotoxicity and stemness were inhibited. Oligo-Fucoidan plus olaparib better inhibited the formation of TNBC stem cell mammospheroids with decreased subpopulations of CD44high/CD24low and EpCAMhigh cells than monotherapy. Importantly, Oligo-Fucoidan plus olaparib repressed the oncogenic interleukin-6 (IL-6)/p-EGFR/PD-L1 pathway, glucose uptake and lactate production. Oligo-Fucoidan induced immunoactive and antitumoral M1 macrophages and attenuated the side effects of olaparib, such as the promotion on immunosuppressive and protumoral M2 macrophages. Furthermore, olaparib plus Oligo-Fucoidan dramatically suppressed M2 macrophage invasiveness and repolarized M2 to the M0-like (F4/80high) and M1-like (CD80high and CD86high) phenotypes. In addition, olaparib- and Oligo-Fucoidan-pretreated TNBC cells resulted in the polarization of M0 macrophages into CD80(+) M1 but not CD163(+) M2 macrophages. Importantly, olaparib supplemented with oral administration of Oligo-Fucoidan in mice inhibited postsurgical TNBC recurrence and metastasis with increased cytotoxic T cells in the lymphatic system and decreased regulatory T cells and M2 macrophages in tumors. CONCLUSION: Olaparib supplemented with natural compound Oligo-Fucoidan is a novel therapeutic strategy for reprogramming cancer stemness, metabolism and the microenvironment to prevent local postsurgical recurrence and distant metastasis. The combination therapy may advance therapeutic efficacy that prevent metastasis, chemoresistance and mortality in TNBC patients.

PARPi treatment enhances radiotherapy-induced ferroptosis and antitumor immune responses via the cGAS signaling pathway in colorectal cancer.

In cancer cells, poly (ADP-ribose) polymerase (PARP)-1 and PARP2 initiate and regulate DNA repair pathways to protect against DNA damage and cell death caused by radiotherapy or chemotherapy. Radiotherapy and PARP inhibitors (PARPis) have been combined in clinical trials, but their action mechanisms remain unclear. Here, we show that activated by ionizing radiation (IR) generated dsDNA, cyclic GMP-AMP synthase (cGAS) signaling promoted regulated cell death, specifically ferroptosis, via the activating transcription factor 3 (ATF3)-solute carrier family 7 member 11 axis and the antitumor immune response via the interferon-ß-CD8+ T cell pathway. Niraparib, a widely used PARPi, augmented cGAS-mediated ferroptosis and immune activation. In colorectal cancer models, cGAS knockdown (KD) compromised IR-induced ferroptosis via downregulation of ATF3 (key ferroptosis regulator) expression. cGAS depletion reversed IR-induced infiltration of CD8+ T or CD8+GZMB+ T cells in the cGAS KD group. Survival analysis of paired tumor samples before and after standard radiotherapy revealed that high expression levels of cGAS, ATF3, and PTGS2 and high density of CD8+ T cells resulted in a significantly high disease-free survival rate in patients with rectal cancer. Therefore, PARPi treatment increases the cytoplasmic accumulation of dsDNA caused by IR, triggering the cGAS signaling-mediated tumor control in cancer cell lines and mouse xenograft models.

Cyclooxygenase-2 activates the free radical-mediated apoptosis of polymorphonuclear leukocytes in the maneb- and paraquat-intoxicated rats.

Overproduction of free radicals and inflammation could lead to maneb (MB)- and paraquat (PQ)-induced toxicity in the polymorphonuclear leukocytes (PMNs). Cyclooxygenase-2 (COX-2), an inducible COX, is imperative in the pesticides-induced pathological alterations. However, its role in MB- and PQ-induced toxicity in the PMNs is not yet clearly deciphered. The current study explored the contribution of COX-2 in MB- and PQ-induced toxicity in the PMNs and the mechanism involved therein. Combined MB and PQ augmented the production of free radicals, lipid peroxides and activity of superoxide dismutase (SOD) in the rat PMNs. While combined MB and PQ elevated the expression of COX-2 protein, activation of nuclear factor-kappa B (NF-κB) and phosphorylation of c-Jun N-terminal kinase (JNK), release of mitochondrial cytochrome c and levels of procaspase-3/9 were attenuated in the PMNs. Celecoxib (CXB), a COX-2 inhibitor, ameliorated the combined MB and PQ-induced modulations in the PMNs. MB and PQ augmented the free radical generation, COX-2 protein expression, NF-κB activation and JNK phosphorylation and reduced the cell viability of cultured rat PMNs and human leukemic HL60. MB and PQ elevated mitochondrial cytochrome c release and poly (ADP-ribose) polymerase cleavage whilst procaspase-3/9 levels were attenuated in the cultured PMNs. MB and PQ also increased the levels of phosphorylated c-jun and caspase-3 activity in the HL60 cells. CXB; SP600125, a JNK-inhibitor and pyrrolidine dithiocarbamate (PDTC), a NF-κB inhibitor, rescued from MB and PQ-induced changes in the PMNs and HL60 cells. However, CXB offered the maximum protection among the three. The results show that COX-2 activates apoptosis in the PMNs following MB and PQ intoxication, which could be linked to NF-κB and JNK signaling.

Olaparib synergizes with arsenic trioxide by promoting apoptosis and ferroptosis in platinum-resistant ovarian cancer.

Poly (ADP-ribose) polymerase (PARP) inhibitors are efficacious in treating platinum-sensitive ovarian cancer (OC), but demonstrate limited efficiency in patients with platinum-resistant OC. Thus, further investigations into combined strategies that enhance the response to PARP inhibitors (PARPi) in platinum-resistant OC are required. The present study aimed to investigate the combined therapy of arsenic trioxide (ATO) with olaparib, a common PARPi, and determine how this synergistic cytotoxicity works in platinum-resistant OC cells. Functional assays demonstrated that the combined treatment of olaparib with ATO significantly suppressed cell proliferation and colony formation, and enhanced DNA damage as well as cell apoptosis in A2780-CIS and SKOV3-CIS cell lines. Results of the present study also demonstrated that a combination of olaparib with ATO increased lipid peroxidation and eventually triggered ferroptosis. Consistently, the combined treatment synergistically suppressed tumor growth in mice xenograft models. Mechanistically, ATO in combination with olaparib activated the AMPK α pathway and suppressed the expression levels of stearoyl-CoA desaturase 1 (SCD1). Collectively, results of the present study demonstrated that treatment with ATO enhanced the effects of olaparib in platinum-resistant OC.

Combination of talazoparib and olaparib enhanced the curcumin-mediated apoptosis in oral cancer cells by PARP-1 trapping.

PURPOSE: Inhibition of Poly (ADP-ribose) Polymerases (PARP) results in the blocking of DNA repair cascades that eventually leads to apoptosis and cancer cell death. PARP inhibitors (PARPi) exhibit their actions either by inhibiting PARP-induced PARylation and/or by trapping PARP at the DNA damage site. But, the mechanism of PARPi-mediated induction of cellular toxicity via PARP-trapping is largely unknown. METHODS: The cellular toxicity of PARPi [Talazoparib (BMN) and/or Olaparib (Ola)] was investigated in oral cancer cells and the underlying mechanism was studied by using in vitro, in silico, and in vivo preclinical model systems. RESULTS: The experimental data suggested that induction of DNA damage is imperative for the optimal effectiveness of PARPi. Curcumin (Cur) exhibited maximum DNA damaging capacity in comparison to Resveratrol and 5-Flurouracil. Combination of BMN + Ola induced cell death in Cur pre-treated cells at much lower concentrations than their individual treatments. BMN + Ola treatment deregulated the BER cascade, potentiated PARP-trapping, caused cell cycle arrest and apoptosis in Cur pre-treated cells in a much more effective manner than their individual treatments. In silico data indicated the involvement of different amino acid residues which might play important roles in enhancing the BMN + Ola-mediated PARP-trapping. Moreover, in vivo mice xenograft data also suggested the BMN + Ola-mediated enhancement of apoptotic potentiality of Cur. CONCLUSION: Thus, induction of DNA damage was found to be essential for optimal functioning of PARPi and BMN + Ola combination treatment enhanced the apoptotic potentiality of Cur in cancer cells by enhancing the PARP-trapping activity via modulation of BER cascade.

The preventive effect of loganin on oxidative stress-induced cellular damage in human keratinocyte HaCaT cells.

Loganin is a type of iridoid glycosides isolated from Corni fructus and is known to have various pharmacological properties, but studies on its antioxidant activity are still lacking. Therefore, in this study, the preventive effect of loganin on oxidative stress-mediated cellular damage in human keratinocyte HaCaT cells was investigated. Our results show that loganin pretreatment in a non-toxic concentration range significantly improved cell survival in hydrogen peroxide (H2O2)-treated HaCaT cells, which was associated with inhibition of cell cycle arrest at the G2/M phase and induction of apoptosis. H2O2-induced DNA damage and reactive oxygen species (ROS) generation were also greatly reduced in the presence of loganin. Moreover, H2O2 treatment enhanced the cytoplasmic release of cytochrome c, upregulation of the Bax/Bcl-2 ratio and degradation of cleavage of poly (ADP-ribose) polymerase, whereas loganin remarkably suppressed these changes. In addition, loganin obviously attenuated H2O2-induced autophagy while inhibiting the increased accumulation of autophagosome proteins, including as microtubule-associated protein 1 light chain 3-II and Beclin-1, and p62, an autophagy substrate protein, in H2O2-treated cells. In conclusion, our current results suggests that loganin could protect HaCaT keratinocytes from H2O2-induced cellular injury by inhibiting mitochondrial dysfunction, autophagy and apoptosis. This finding indicates the applicability of loganin in the prevention and treatment of skin diseases caused by oxidative damage.

Effects of Ubiquinol and/or D-ribose in Patients With Heart Failure With Preserved Ejection Fraction.

Patients with heart failure with preserved ejection fraction (HFpEF) have few pharmacologic therapies, and it is not known if supplementing with ubiquinol and/or d-ribose could improve outcomes. The overall objective of this study was to determine if ubiquinol and/or d-ribose would reduce the symptoms and improve cardiac performance in patients with HFpEF. This was a phase 2 randomized, double-blind, placebo-controlled trial of 216 patients with HFpEF who were ≥ 50 years old with a left ventricular ejection fraction (EF) ≥ 50%. A total of 4 study groups received various supplements over 12 weeks: Group 1 received placebo ubiquinol capsules and d-ribose powder, Group 2 received ubiquinol capsules (600 mg/d) and placebo d-ribose powder, Group 3 received placebo ubiquinol capsules with d-ribose powder (15 g/d), and Group 4 received ubiquinol capsules and d-ribose powder. There were 7 outcome measures for this study: Kansas City Cardiomyopathy Questionnaire (KCCQ) clinical summary score, level of vigor using a subscale from the Profile of Mood States, EF, the ratio of mitral peak velocity of early filling to early diastolic mitral annular velocity (septal E/e' ratio), B-type natriuretic peptides, lactate/adenosine triphosphate ratio, and the 6-minute walk test. Treatment with ubiquinol and/or d-ribose significantly improved the KCCQ clinical summary score (17.30 to 25.82 points), vigor score (7.65 to 8.15 points), and EF (7.08% to 8.03%) and reduced B-type natriuretic peptides (-72.02 to -47.51) and lactate/adenosine triphosphate ratio (-4.32 to -3.35 × 10-4). There were no significant increases in the septal E/e' or the 6-minute walk test. In conclusion, ubiquinol and d-ribose reduced the symptoms of HFpEF and increased the EF. These findings support the use of these supplements in addition to standard therapeutic treatments for patients with HFpEF.