X-ray repair cross-complementing protein 1 (XRCC1) loss promotes ß-lapachone -induced apoptosis in pancreatic cancer cells.

BACKGROUND: ß-lapachone (ß-lap), the NQO1 bioactivatable drug, is thought to be a promising anticancer agent. However, the toxic side effects of ß-lap limit the drug use, highlighting the need for a thorough understanding of ß-lap's mechanism of action. ß-lap undergoes NQO1-dependent futile redox cycling, generating massive ROS and oxidative DNA lesions, leading to cell death. Thus, base excision repair (BER) pathway is an important resistance factor. XRCC1, a scaffolding component, plays a critical role in BER. METHODS: We knocked down XRCC1 expression by using pLVX-shXRCC1 in the MiaPaCa2 cells and BxPC3 cells and evaluated ß-lap-induced DNA lesions by γH2AX foci formation and alkaline comet assay. The cell death induced by XRCC1 knockdown + ß-lap treatment was analysed by relative survival, flow cytometry and Western blotting analysis. RESULTS: We found that knockdown of XRCC1 significantly increased ß-lap-induced DNA double-strand breaks, comet tail lengths and cell death in PDA cells. Furthermore, we observed combining XRCC1 knockdown with ß-lap treatment switched programmed necrosis with ß-lap monotherapy to caspase-dependent apoptosis. CONCLUSIONS: These results indicate that XRCC1 is involved in the repair of ß-lap-induced DNA damage, and XRCC1 loss amplifies sensitivity to ß-lap, suggesting targeting key components in BER pathways may have the potential to expand use and efficacy of ß-lap for gene-based therapy.

PARP1 as a prognostic biomarker for human cancers: a meta-analysis.

Aim: A comprehensive meta-analysis was carried out to evaluate the association between high PARP1 expression and clinical outcomes in diverse types of cancers. Materials & methods: The electronic databases for all articles about PARP1 expression and cancers were searched. Additionally, bioinformatics analysis was utilized to validate the results of the meta-analysis. Results: Fifty-two studies with a total of 7140 patients were included in the current meta-analysis. High PARP1 expression was found to be significantly associated with poor overall survival and recurrence in various cancers, which were further strengthened and complemented by the results of bioinformatic analysis. Furthermore, increased PAPR1 expression was also related to clinicopathological features. Conclusion: Our findings confirmed that PARP1 might be a promising biomarker for prognosis in human cancers.

Ubiquitin-Specific Protease 14 (USP14) Aggravates Inflammatory Response and Apoptosis of Lung Epithelial Cells in Pneumonia by Modulating Poly (ADP-Ribose) Polymerase-1 (PARP-1).

Pneumonia is one of the common respiratory diseases in pediatrics. Ubiquitin-specific protease 14 (USP14) contributes the progress of inflammation-associated diseases. Poly (ADP-ribose) polymerase-1 (PARP-1) involves in the signal transduction of inflammatory pulmonary disease. This study aims to identify the precise function and elaborate the regulatory mechanism of USP14/PARP-1 in the injury of lung epithelial cells. Human lung epithelial BEAS-2B cells received lipopolysaccharide (LPS) (0, 1, 5, and 10 mg/L) treatment for 16 h, establishing in vitro pneumonia model. USP14 protein and mRNA levels in LPS-injured lung epithelial cells were separately assessed using western blot and RT-qPCR analysis. Lung epithelial cells were transfected with siRNA-USP14 or OV-USP14 to perform gain- or loss-of-function experiments. CCK-8 assay was applied to assess cell viability. TUNEL staining and western blot analysis were adopted to determine cell apoptosis. In addition, release of inflammatory cytokines and nitric oxide (NO) was detected using the commercial kits. Meanwhile, PARP-1 protein levels in LPS-injured lung epithelial cells were detected by performing western blot assay. Moreover, Co-IP assay was utilized for detection of the interaction between USP14 and PARP-1. The regulatory effects of PARP-1 on USP14 function in LPS-injured lung epithelial cells were also investigated. LPS dose-dependently reduced viability of lung epithelial cells and elevated USP14 protein. USP14 combined with PARP-1 and increased PARP-1 expression. USP14 elevation exacerbated inflammatory injury and boosted the apoptosis of LPS-injured lung epithelial cells, which was reversed upon downregulation of PARP-1. To sum up, USP14 promotion exacerbated inflammatory injury and boosted the apoptosis of LPS-injured lung epithelial cells by upregulating PARP-1 expression. These findings may represent a therapeutic target for clinical intervention in pneumonia.

L-Arginine protects mouse Leydig cells against T-2 toxin-induced apoptosis in vitro.

To explore the protective mechanism of L-arginine against T-2 toxin-induced apoptosis in mouse Leydig cells, we investigated whether L-arginine can prevent T-2 toxin-induced apoptosis in mouse Leydig cells and explored the underlying mechanisms. Leydig cells were isolated and cultured with control, T-2 toxin (10 nM), L-arginine (0.25, 0.5, and 1.0 mM), and T-2 toxin (10 nM T-2 toxin) + L-arginine (0.25, 0.5, or 1.0 mM) for 24 h. Cells and supernatants were harvested to examine proliferation of the cells, the apoptosis rate, activity of caspase-3 and mitochondria, and the gene expression levels of Bcl-2, Bax, PARP, and caspase-3. Results showed that proliferation and mitochondrial activity of Leydig cells were inhibited by administration of T-2 toxin. Bcl-2 gene expression levels was decreased, while the gene expression levels of Bax and PARP were increased, which could trigger mitochondria-mediated apoptosis, activate downstream caspase-3, and then increased caspase-3 at both activity and gene expression levels. The expression of the Bcl-2 gene was upregulated and the expression of Bax, caspase-3, and PARP gene were downregulated when L-arginine was added to the cultured cells. The results of this study showed that L-arginine could block T-2 toxin-induced apoptosis in mouse Leydig cells by regulating specific intracellular death-related pathways.

Twist-mediated PAR1 induction is required for breast cancer progression and metastasis by inhibiting Hippo pathway.

Breast cancer is considered to be the most prevalent cancer in women worldwide, and metastasis is the primary cause of death. Protease-activated receptor 1 (PAR1) is a GPCR family member involved in the invasive and metastatic processes of cancer cells. However, the functions and underlying mechanisms of PAR1 in breast cancer remain unclear. In this study, we found that PAR1 is highly expressed in high invasive breast cancer cells, and predicts poor prognosis in ER-negative and high-grade breast cancer patients. Mechanistically, Twist transcriptionally induces PAR1 expression, leading to inhibition of Hippo pathway and activation of YAP/TAZ; Inhibition of PAR1 suppresses YAP/TAZ-induced epithelial-mesenchymal transition (EMT), invasion, migration, cancer stem cell (CSC)-like properties, tumor growth and metastasis of breast cancer cells in vitro and in vivo. These findings suggest that PAR1 acts as a direct transcriptionally target of Twist, can promote EMT, tumorigenicity and metastasis by controlling the Hippo pathway; this may lead to a potential therapeutic target for treating invasive breast cancer.

Expression of poly-ADP-ribose polymerase (PARP) in endometrial adenocarcinoma: Prognostic potential.

BACKGROUND: In the United States endometrial carcinoma is the most common female gynecologic malignancy. An average of more than 60,000 new cases of endometrial carcinomas have been diagnosed yearly over the past 5 years, with a higher incidence occurring in the central Appalachian states of Ohio and West Virginia. In the U.S., the national average of newly diagnosed endometrial carcinomas is 26.8 in every 100,000 women, while in the states of Ohio and West Virginia the average is 30.5 and 31.1 in every 100,000 women, respectively. This notable increase in the incidence of endometrial carcinomas may be due a variety of elevated risk factors including but not limited to: tobacco use, obesity, and genetic predisposition of the predominant demographic. The American Cancer Society estimates that approximately 55,000 new cases of endometrial carcinoma will be diagnosed in 2020 yet, this disease is widely considered understudied and under-represented in mainstream cancer research circles. METHODS: The aim of this study was to quantitate the co-expression of two DNA repair proteins poly-ADP-ribose polymerase 1 and 2 (Parp-1 and Parp-2) by enzyme- linked immuno-sorbent assay (ELISA) in 60 endometrioid endometrial tumor samples and compare their expression to matched non-malignant endometrial tissue from the same corresponding donors from central Appalachia. RESULTS: We found that Parp-1 was significantly overexpressed in endometrial carcinoma relative to corresponding normal tissue. This overexpression implicates Parp inhibition therapy as a possible treatment for the disease. Our results also found a protective effect of native Parp-2 expression in non-malignant endometrial tissue with each 1 ng/mL increase in PARP-2 concentration in normal tissue was associated with a 10 % reduction in the hazard of tumor progression (HR = 0.90; p = 0.039) and a 21 % reduction in the hazard of death (HR = 0.79; p = 0.044). CONCLUSIONS: This study demonstrated the over-expression of the druggable target Parp-1 in endometrial adenocarcinoma and observed a strong negative correlation of native Parp-2 expression and disease progression via the quantification of the Parp proteins using enzyme- linked immuno-sorbent assay (ELISA) assays.

Let-7e Suppresses DNA Damage Repair and Sensitizes Ovarian Cancer to Cisplatin through Targeting PARP1.

Increased DNA damage repair is one of the mechanisms implicated in cisplatin resistance. Our previous study indicated that the deregulation of let-7e promoted cisplatin resistance and that let-7e could suppress DNA double-strand break repair in ovarian cancer. In this study, we further characterized the role of let-7e in DNA damage repair and cisplatin resistance in ovarian cancer, and investigated the underlying mechanisms. The alkaline and neutral comet assay indicated that let-7e impeded both DNA single- and double-strand break repairs through downregulating its target gene PARP1. In vitro and in vivo experiments provided evidence that the let-7e-PARP1-DNA repair axis was involved in the modulation of cisplatin sensitivity in ovarian cancer. Contrary to let-7e, PARP1 was overexpressed in cisplatin-resistant ovarian cancer tissues, and patients with high PARP1 expression exhibited poor progression-free survival (PFS) and overall survival (OS). Multivariate logistic and Cox regression analyses showed that let-7e and FIGO stage were independent prognostic factors for PFS and OS, whereas let-7e and PARP1 were able to independently predict chemotherapy response. Taken together, our results indicated that low expression of let-7e promoted DNA single- and double-strand break repairs and subsequently contributed to cisplatin resistance by relieving the suppression on PARP1 in ovarian cancer. IMPLICATIONS: Targeting the let-7e-PARP1-DNA repair axis might be an effective strategy for the treatment of chemoresistant ovarian cancer.

Effect of IL-1ß on apoptosis of synovial cells in rheumatoid arthritis rats via the NF-κB pathway.

OBJECTIVE: The aim of this study was to investigate the role of interleukin-1ß (IL-1ß) in the apoptosis of synovial cells in rheumatoid arthritis (RA) rats, and to explore the underlying mechanism. MATERIALS AND METHODS: The apoptosis of the synovial cells in RA rats in the IL-1ß group and the control group was analyzed by scoring under an electron microscope. The expressions of cleaved-poly (ADP-ribose) polymerase (PARP), PARP and anti-apoptosis gene products in synovial cells of IL-1ß treated RA rats were explored as well. Meanwhile, the expressions of B-cell lymphoma 2 (Bcl-2), Bcl-xL, and Active-Caspase3 in the synovial cells of RA rats with IL-1ß treatment were evaluated by the Western blotting. To further clarify the relationship between IL-1ß and the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway in the synovial cells of RA rats, the expressions of NF-κB regulated the gene products of matrix metalloproteinase-3 (MMP-3), MMP-9, cyclooxygenase-2 (Cox-2), and vascular endothelial growth factor (VEGF) in synovial cells of RA rats after that we investigated the treatment with IL-1ß (was investigated). In addition, the expression of NF-κB in the synovial cells of RA rats treated with IL-1ß was determined. RESULTS: The results showed that, compared with the control group, IL-1ß treatment significantly increased the number of apoptotic cells. This meant that IL-1ß treatment could promote the apoptosis of the synovial cells (p<0.05). IL-1ß treatment significantly promoted the expression level of cleaved-PARP (p<0.05). However, it remarkably reduced the expressions of Bcl-2 and Bcl-xL (p<0.05). Meanwhile, the level of the active-Caspase3 in the synovial cells of RA rats treated with IL-1ß was significantly enhanced (p<0.01). In comparison with the control group, the IL-1ß group exhibited significantly elevated expressions of NF-κB-regulated gene products in the synovial cells of RA rats (p<0.01). Besides, the positive markers of the activated NF-κB were detected in the synovial cells of RA rats in the IL-1ß group and the control group. The results demonstrated that they were mainly located in the nucleus of the IL-1ß group. CONCLUSIONS: IL-1ß can promote the apoptosis of the synovial cells in RA rats via the NF-κB pathway.

Bone marrow PARP1 mRNA levels predict response to treatment with 5-azacytidine in patients with myelodysplastic syndrome.

Poly (ADP-ribose) polymerase 1 (PARP1) is a nuclear enzyme that participates in the DNA repair of malignant cells, with various consequences on their survival. We have recently shown that PARP1 mRNA levels in the bone marrow of patients with myelodysplastic syndrome (MDS) are correlated to prognosis. To evaluate PARP1 as a biomarker of response to 5-azacytidine in patients with MDS, we measured PARP1 mRNA levels by a quantitative real-time PCR in diagnostic bone marrow samples of 77 patients with MDS treated with 5-azacytidine. Patients with higher PARP1 mRNA levels had a better response to 5-azacytidine per the IWG criteria (p = 0.006) and a longer median survival after 5-azacytidine initiation (p = 0.033). Multivariate analysis revealed that PARP1 mRNA level was the only factor affecting response to treatment and survival after treatment with 5-azacytidine. A next-generation sequencing for 40 genes of interest in MDS and quantification of the methylation levels of the PARP1 promoter were also carried out in a subset of samples (16 and 18 samples respectively). It is the first time that a single, easily measurable biomarker shows a clear correlation with response to treatment and survival in a patient population consisting of previously untreated patients with MDS homogeneously treated with 5-azacytidine. The fact that PARP1 is also a treatment target in several malignancies underscores the importance of our finding for the potential use of PARP1 inhibitors in MDS.

ERCC1-XPF deficiency is a predictor of olaparib induced synthetic lethality and platinum sensitivity in epithelial ovarian cancers.

PURPOSE: PARP inhibitor maintenance therapy in platinum sensitive sporadic ovarian cancers improves progression free survival. However, biomarker for synthetic lethality in platinum sensitive sporadic disease is yet to be defined. ERCC1-XPF heterodimer is a key player in nucleotide excision repair (NER) involved in the repair of platinum induced DNA damage. In the current study, we tested whether ERCC1-XPF deficiency would predict synthetic lethality to the PARP inhibitor Olaparib and platinum sensitivity in ovarian cancers. METHODS: ERCC1, XPF and PARP1 protein expression was evaluated in tumors from a cohort of 331 patients treated at Nottingham University Hospitals and correlated to clinicopathological features and survival. Pre-clinically, ERCC1 and XPF was depleted in A2780 (platinum sensitive) and A2780cis (platinum resistant) ovarian cancer cell lines and tested for platinum sensitivity as well as for Olaparib induced synthetic lethality. RESULTS: Low ERCC1 was significantly associated with improved progression free survival (PFS) in patients with ovarian cancers in univariate (p = 0.001) and multivariate (p = 0.002) analysis. In addition, low ERCC1/low XPF (p = 0.003) or low ERCC1/low PARP1 (p = 0.0001) tumors was also linked to better PFS compared to high ERCC1/high XPF or high ERCC1/high PARP1 tumors. Pre-clinically, ERCC1 or XPF depletion not only increased platinum sensitivity but also increased toxicity to Olaparib therapy. Increased sensitivity was associated with DNA double strand breaks (DSBs) accumulation, cell cycle arrest and increased apoptosis. CONCLUSION: The data provide evidence that low ERCC1 is not only a predictor of platinum sensitivity but is also a promising biomarker for Olaparib induced synthetic lethality in ovarian cancers.

Histone deacetylase inhibitors induce complex host responses that contribute to differential potencies of these compounds in HIV reactivation.

Histone deacetylase (HDAC) inhibitors (HDACis) have been widely tested in clinical trials for their ability to reverse HIV latency but have yielded only limited success. One HDACi, suberoylanilide hydroxamic acid (SAHA), exhibits off-target effects on host gene expression predicted to interfere with induction of HIV transcription. Romidepsin (RMD) has higher potency and specificity for class I HDACs implicated in maintaining HIV provirus in the latent state. More robust HIV reactivation has indeed been achieved with RMD use ex vivo than with SAHA; however, reduction of viral reservoir size has not been observed in clinical trials. Therefore, using RNA-Seq, we sought to compare the effects of SAHA and RMD on gene expression in primary CD4+ T cells. Among the genes whose expression was modulated by both HDACi agents, we identified genes previously implicated in HIV latency. Two genes, SMARCB1 and PARP1, whose modulation by SAHA and RMD is predicted to inhibit HIV reactivation, were evaluated in the major maturation subsets of CD4+ T cells and were consistently either up- or down-regulated by both HDACi compounds. Our results indicate that despite having different potencies and HDAC specificities, SAHA and RMD modulate an overlapping set of genes, implicated in HIV latency regulation. Some of these genes merit exploration as additional targets to improve the therapeutic outcomes of "shock and kill" strategies. The overall complexity of HDACi-induced responses among host genes with predicted stimulatory or inhibitory effects on HIV expression likely contributes to differential HDACi potencies and dictates the outcome of HIV reactivation.

53BP1 as a potential predictor of response in PARP inhibitor-treated homologous recombination-deficient ovarian cancer.

OBJECTIVE: Poly(ADP-ribose) polymerase (PARP) inhibitors have shown substantial activity in homologous recombination- (HR-) deficient ovarian cancer and are undergoing testing in other HR-deficient tumors. For reasons that are incompletely understood, not all patients with HR-deficient cancers respond to these agents. Preclinical studies have demonstrated that changes in alternative DNA repair pathways affect PARP inhibitor (PARPi) sensitivity in ovarian cancer models. This has not previously been assessed in the clinical setting. METHODS: Clonogenic and plasmid-based HR repair assays were performed to compare BRCA1-mutant COV362 ovarian cancer cells with or without 53BP1 gene deletion. Archival biopsies from ovarian cancer patients in the phase I, open-label clinical trial of PARPi ABT-767 were stained for PARP1, RAD51, 53BP1 and multiple components of the nonhomologous end-joining (NHEJ) DNA repair pathway. Modified histochemistry- (H-) scores were determined for each repair protein in each sample. HRD score was determined from tumor DNA. RESULTS: 53BP1 deletion increased HR in BRCA1-mutant COV362 cells and decreased PARPi sensitivity in vitro. In 36 women with relapsed ovarian cancer, responses to the PARPi ABT-767 were observed exclusively in cancers with HR deficiency. In this subset, 7 of 18 patients (39%) had objective responses. The actual HRD score did not further correlate with change from baseline tumor volume (r = 0.050; p = 0.87). However, in the HR-deficient subset, decreased 53BP1 H-score was associated with decreased antitumor efficacy of ABT-767 (r = -0.69, p = 0.004). CONCLUSION: Differences in complementary repair pathways, particularly 53BP1, correlate with PARPi response of HR-deficient ovarian cancers.

MicroRNA-7-5p Promotes Cisplatin Resistance of Cervical Cancer Cells and Modulation of Cellular Energy Homeostasis by Regulating the Expression of the PARP-1 and BCL2 Genes.

BACKGROUND Resistance to cisplatin results in recurrence or relapse of cervical cancer in women. An understanding of the mechanisms of cisplatin resistance will be important to improve the efficacy of cisplatin treatment. The aim of this study was to investigate the role of microRNA-7-5p (mir-7-5p) in cisplatin-resistant cervical cancer cells in vitro. MATERIAL AND METHODS The expression levels of miR-7-5p were detected in cisplatin-resistant cervical cancer cells, HeLa, and SiHa cells (HPV16-positive), and in clinical tissue samples, using miR-7-5p inhibition and a luciferase reporter assay. Fifteen paired cervical cancer tissue samples and adjacent normal cervical tissues were obtained from 15 patients who underwent surgery for cervical cancer. Western blot and flow cytometry were used to investigate cell apoptosis. The expression of mir-7-5p was detected by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). RESULTS The level of miR-7-5p was increased in cisplatin-resistant HeLa and SiHa cervical cancer cells. Increased expression of miR-7-5p inhibited DNA repair by modulating the expression of poly (ADP-ribose) polymerase 1 (PARP-1), reducing energy consumption, and promoting autophagy via suppression of the expression of Bcl-2. These findings supported that increasing energy generation and reducing energy consumption, resulted in miR-7-5p maintaining energy homeostasis during cisplatin treatment. CONCLUSIONS The findings of this study showed that there was a protective role of miR-7-5p in cervical cancer cells treated with cisplatin and that miR-7-5p expression maintained energy homeostasis in cisplatin-resistant cervical cancer cells. However, miR-7-5p reduced energy consumption via inhibiting PARP-1 expression, and miR-7-5p increased energy generation by suppressing the expression of Bcl-2.

Autophagy induced by cardamonin is associated with mTORC1 inhibition in SKOV3 cells.

BACKGROUND: The mammalian target of rapamycin (mTOR) integrates energy level to modulate cell proliferation and autophagy. Cardamonin exhibits anti-proliferative activity through inhibiting mTOR. In this study, the effect of cardamonin on autophagy and its mechanism on mTOR inhibition were investigated. METHODS: Cell viability and proliferation were measured by MTT assay and BrdU incorporation, respectively. Cell apoptosis was assayed by flow cytometry and cell autophagy was detected by electron microscopy and GFP-LC3 fluorescence. The mechanism of cardamonin on mTORC1 inhibition was investigated by Raptor siRNA and Raptor over-expression. RESULTS: The cell viability and proliferation were inhibited by cardamonin. The autophagosomes and the protein level of LC3-II were increased by cardamonin. Cell apoptosis and the levels of cleaved PARP and Caspase-3 were increased by cardamonin. Cardamonin inhibited the phosphorylation of mTOR and ribosome S6 protein kinase 1 (S6K1) as well as the protein level of regulatory associated protein of mTOR (Raptor). However, cardamonin had no effect on the component of mTORC2 and its downstream substrate Akt. The inhibitory effect of cardamonin on the phosphorylation of mTOR and S6K1 was eliminated by Raptor knockdown with siRNA, whereas this effect of cardamonin was stronger than that of rapamycin and AZD8055 in Raptor over-expression cells. Cell viability was inhibited by cardamonin in both Raptor knockdown and Raptor over-expression cells, which was consistent with the inhibitory effect of cardamonin on mTOR. CONCLUSION: These findings demonstrated that the autophagy induced by cardamonin was associated with mTORC1 inhibition through decreasing the protein level of Raptor in SKOV3 cells.

Predictive value of epithelial-mesenchymal-transition (EMT) signature and PARP-1 in prostate cancer radioresistance.

INTRODUCTION: Epithelial-mesenchymal-transition (EMT) has been previously identified as a contributor to prostate cancer progression to metastasis and therapeutic resistance to antiandrogens and radiotherapy. In this study we conducted a retrospective analysis to investigate the significance of radiation-induced EMT and consequential changes to the tumor microenvironment in biochemical recurrence and response to radiotherapy in prostate cancer patients. METHODS: Expression profiling and localization for EMT effectors, E-Cadherin, N-Cadherin, ß-catenin and Vimentin was assessed in human prostate tumor specimens pre- and post-radiotherapy and correlated with biochemical recurrence. In addition, immunoreactivity of the DNA repair enzyme, polymerase (PARP-1) and the cytoskeletal-remodeling regulator, cofilin was evaluated in prostate tumor specimens pre- and post-radiotherapy and correlated with pre-treatment prostate-specific antigen levels (PSA). RESULTS: Our findings identified that characteristic changes associated with the EMT phenotype and its reversal to mesenchymal-epithelial-transition (MET) within the tumor microenvironment correlate with biochemical recurrence and resistance to radiotherapy among prostate cancer patients. Moreover, elevated PARP-1 expression among the tumor cells undergoing EMT implicates that DNA repair mechanisms may potentially reverse the cytotoxic effects of radiotherapy-induced DNA breaks. CONCLUSIONS: Our results suggest that EMT programming effectors, integrated with the actin cytoskeleton regulator cofilin and mesenchymal PARP-1 expression profile provide a signature of potential predictive significance of therapeutic response to radiotherapy in a subset of prostate cancer patients.

Effects of Poly(ADP-Ribose) Polymerase-1 Inhibition in a Neonatal Rodent Model of Hypoxic-Ischemic Injury.

BACKGROUND: Hypoxia ischemia (HI) to the developing brain occurs in 1-6 in 1000 live births. Large numbers of survivors have neurological long-term sequelae. However, mechanisms of recovery after HI are not understood and preventive measures or clinical treatments are not effective. Poly(ADP-ribose) polymerase-1 is overactivated in response to ischemia. In neonatal mice HI activates PARP-1 but its role in perinatal brain injury remains uncertain. OBJECTIVE: Aim of this study was to explore the effect of TES448 (PARP-1-inhibitor) and hypothermia after an ischemic insult. DESIGN AND METHODS: 10-day-old Wistar rats underwent HI. TES448 was given 10 min, 3 hrs, and 6 hrs after hypoxia. Hypothermia was started 30 min after HI and brains were dissected at P12. Western blotting and histological staining were used to evaluate for degree of injury. RESULTS: Protein expression of PARP-1 levels was diminished after TES448 treatment. Cresyl violet and TUNEL staining revealed decreased injury in male rat pups following TES448 and combined treatment. Female rats showed increased numbers of TUNEL-positive cells after combined therapy. TES448 inhibited microglia activation after hypoxic-ischemic injury. A cellular response including NeuN, Olig2, and MBP was not affected by PARP-1-inhibition. CONCLUSIONS: Inhibition of PARP-1 and hypothermia lead to an alteration of injury but this effect is sexually dimorphic.

Adaptive response in mouse bone marrow stromal cells exposed to 900MHz radiofrequency fields: Impact of poly (ADP-ribose) polymerase (PARP).

This study examined whether non-ionizing radiofrequency fields (RF) exposure is capable of inducing poly (ADP-ribose) polymerase-1 (PARP-1) in bone marrow stromal cells (BMSCs) and whether it plays a role in RF-induced adaptive response (AR). Bone marrow stromal cells (BMSCs) were exposed to 900MHz RF at 120µW/cm2 power flux density for 3h/day for 5days and then challenged with a genotoxic dose of 1.5Gy gamma-radiation (GR). Some cells were also treated with 3-aminobenzamide (3-AB, 2mM final concentration), a potent inhibitor of PARP-1. Un-exposed and sham (SH)-exposed control cells as well as positive control cells exposed to gamma radiation (GR) were included in the experiments. The expression of PARP-1 mRNA and its protein levels as well as single strand breaks in the DNA and the kinetics of their repair were evaluated at several times after exposures. The results indicated the following. (a) Cells exposed to RF alone showed significantly increased PARP-1 mRNA expression and its protein levels compared with those exposed to SH- and GR alone. (b) Treatment of RF-exposed cells with 3-AB had diminished such increase in PARP-1. (c) Cells exposed to RF+GR showed significantly decreased genetic damage as well as faster kinetics of repair compared with those exposed to GR alone. (d) Cells exposed to RF+3-AB+GR showed no such decrease in genetic damage. Thus, the overall date suggested that non-ionizing RF exposure was capable of inducing PARP-1 which has a role in RF-induced AR.

Cannabinoid CB2 receptors are involved in the protection of RAW264.7 macrophages against the oxidative stress: an in vitro study.

Research in the last decades has widely investigated the anti-oxidant properties of natural products as a therapeutic approach for the prevention and the treatment of oxidative-stress related disorders. In this context, several studies were aimed to evaluate the therapeutic potential of phytocannabinoids, the bioactive compounds of Cannabis sativa. Here, we examined the anti-oxidant ability of Cannabigerol (CBG), a non-psychotropic cannabinoid, still little known, into counteracting the hydrogen peroxide (H2O2)-induced oxidative stress in murine RAW264.7 macrophages. In addition, we tested selective receptor antagonists for cannabinoid receptors and specifically CB1R (SR141716A) and CB2R (AM630) in order to investigate through which CBG may exert its action. Taken together, our in vitro results showed that CBG is able to counteract oxidative stress by activation of CB2 receptors. CB2 antagonist pre-treatment indeed blocked the protective effects of CBG in H2O2 stimulated macrophages, while CB1R was not involved. Specifically, CBG exhibited a potent action in inhibiting oxidative stress, by down-regulation of the main oxidative markers (iNOS, nitrotyrosine and PARP-1), by preventing IκB-α phosphorylation and translocation of the nuclear factor-κB (NF-κB) and also via the modulation of MAP kinases pathway. On the other hand, CBG was found to increase anti-oxidant defense of cells by modulating superoxide dismutase-1 (SOD-1) expression and thus inhibiting cell death (results focused on balance between Bax and Bcl-2). Based on its antioxidant activities, CBG may hold great promise as an anti-oxidant agent and therefore used in clinical practice as a new approach in oxidative-stress related disorders.

Biomarker-Based PET Imaging of Diffuse Intrinsic Pontine Glioma in Mouse Models.

Diffuse intrinsic pontine glioma (DIPG) is a childhood brainstem tumor with a universally poor prognosis. Here, we characterize a positron emission tomography (PET) probe for imaging DIPG in vivo In human histological tissues, the probes target, PARP1, was highly expressed in DIPG compared to normal brain. PET imaging allowed for the sensitive detection of DIPG in a genetically engineered mouse model, and probe uptake correlated to histologically determined tumor infiltration. Imaging with the sister fluorescence agent revealed that uptake was confined to proliferating, PARP1-expressing cells. Comparison with other imaging technologies revealed remarkable accuracy of our biomarker approach. We subsequently demonstrated that serial imaging of DIPG in mouse models enables monitoring of tumor growth, as shown in modeling of tumor progression. Overall, this validated method for quantifying DIPG burden would serve useful in monitoring treatment response in early phase clinical trials. Cancer Res; 77(8); 2112-23. ©2017 AACR.

LncRNA-SLC6A9-5:2: A potent sensitizer in 131I-resistant papillary thyroid carcinoma with PARP-1 induction.

Recent studies have indicated that long non-coding RNAs play crucial roles in numerous cancers, including thyroid cancer, while their function in the mechanism of thyroid cancer 131I resistance has not been elucidated to date. The present study identified a functional long non-coding RNA, SLC6A9-5:2, which was involved in the radioactive therapy resistance of thyroid cancer. We demonstrated that SLC6A9-5:2 was remarkably downregulated in 131I-resistant thyroid cancer cell lines and 131I-insensitive patients and was positively correlated with Poly (ADP-ribose) polymerase 1 (PARP-1) expression and its activation. After downregulating SLC6A9 or blocking PARP-1 artificially, the sensitive thyroid cancer cells mostly displayed a tolerant phenotype under 131I exposure. Furthermore, SLC6A9-5:2 overexpression was positively correlated with PARP-1 mRNA and protein levels, which restored the sensitivity of resistant thyroid cancer cells. The present study further revealed that cancer cell death was primarily caused by ATP exhaustion in excessive DNA repair with high PARP-1 activity. In patients with thyroid cancer, a positive correlation between SLC6A9-5:2 and PARP-1 was identified, and low SLC6A9-5:2 expression was associated with a worse prognosis of papillary thyroid carcinoma. Hence, our data provide a new lncRNA-mediated regulatory mechanism implying that SLC6A9-5:2 can be used as a novel therapeutic target for 131I-resistant thyroid cancer.