Suppression Of Apoptotic Pathway Research Articles

Abstract NT-114: CATALYTIC SUBUNITS SWITCH DRIVES RESISTANCE TO EZH2 INHIBITORS IN ARID1A-MUTATED CELLS

Abstract The SWI/SNF chromatin remodeling complex is altered in ~20% of human cancers. ARID1A, a component of the SWI/SNF chromatin-remodeling complex, is the most frequently mutated epigenetic regulator in human cancers. Inactivation of the SWI/SNF complex is synthetically lethal with inhibition of EZH2 activity. EZH2 inhibitors are entering clinical trials for specific tumor types with SWI/SNF mutations. However, mechanisms of de novo or acquired resistance to EZH2 inhibitors in cancers with inactivating SWI/SNF mutations are unknown. Here we show that the switch of the SWI/SNF catalytic subunits from SMARCA4 to SMARCA2 drives resistance to EZH2 inhibitors in ARID1A-mutated ovarian cancer cells. SMARCA4 decease dominates over SMARCA2 increase in the switch. SMARCA4 loss leads to suppression of apoptotic pathways through upregulating anti-apoptotic genes such as BCL2 in the EZH2 inhibitor resistant cells. EZH2 inhibitor resistant ARID1A-mutated cells are hypersensitive to BCL2 inhibitors such as ABT263. ABT263 is sufficient to overcome resistance to EZH2 inhibitor and synergistic with EZH2 inhibitor in vivo in ARID1A-inactivted ovarian tumour mouse models. Together, these data establish that the switch of the SWI/SNF catalytic subunits from SMARCA4 to SMARCA2 underlies the acquired resistance to EZH2 inhibitors and BCL2 inhibition alone or in combination with EZH2 inhibition represents a novel strategy to overcome and/or prevent EZH2 inhibitor resistance in ARID1A-mutated cancers. Given that the SWI/SNF subunits are among the most frequently mutated genes in human cancers and EZH2 inhibitors are in the clinical trials for tumor with mutations in the SWI/SNF complex, we expect our findings to have far-reaching implications for developing cancer epigenetic therapeutics. Citation Format: Shuai Wu, Nail Fatkhutdinov, Takeshi Fukumoto, Benjamin G. Bitler, Pyoung Hwa Park, Andrew V. Kossenkov, Marco Trizzino, Alessandro Gardini, David W. Speicher, Rugang Zhang,. CATALYTIC SUBUNITS SWITCH DRIVES RESISTANCE TO EZH2 INHIBITORS IN ARID1A-MUTATED CELLS [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr NT-114.

Cardioprotective Effects of Phenylethanoid Glycoside-rich Extract from Cistanche deserticola in Ischemia-Reperfusion–Induced Myocardial Infarction in Rats

The aim of the study was to examine and confirm the cardioprotective effect and mechanism of phenylethanoid glycoside-rich extract of Cistanche deserticola (PhG-RE), a well-known natural antioxidant-based active constituents, against ischemia/reperfusion injury using both invivo and invitro approaches. A total of 30 Sprague-Dawley rats were divided in to 3 groups as group 1: sham laparotomy, group 2: IR, and group 3: IR+PhG-RE group (0.25mg/mL/min). Hearts were subjected to 30min of global ischemia followed by 45min of reperfusion. The myocardial infarct size and the activities of creatine kinase isoenzyme (CK-MB) and lactate dehydrogenase (LDH) were measured. Myocardial tissue malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) levels were detected. Western blot analysis was carried out to determine the cardioprotective mechanisms of PhG-RE. Hearts treated with PhG-RE showed a significant reduction in infarct size and decrease in CK-MB and LDH activities. PhG-RE also reduced MDA levels and elevated the activities of GSH-Px, SOD. The expressions of cytochrome-c were significantly reduced in the treated group. A significant upregulation of antiapoptotic proteins Bcl-2/Bax with simultaneous downregulation of cleaved-caspase-3 was observed. The molecular signaling cascade, including phospho-Akt (ser-473) and phospho-GSK3β that lead to the activation or suppression of apoptotic pathway, also showed a significant protective role in the treatment group. The results suggested that the PhG-RE may reduce the oxidative stress in the reperfused myocardium and play a significant role in the inhibition of apoptotic pathways leading to cardioprotection.

MP88-03 POTENTIAL ROLE OF G1P3 IN DEVELOPMENT OF CHEMORESISTANCE IN HIGH GRADE BLADDER CANCER

You have accessJournal of UrologyBladder Cancer: Basic Research & Pathophysiology V1 Apr 2016MP88-03 POTENTIAL ROLE OF G1P3 IN DEVELOPMENT OF CHEMORESISTANCE IN HIGH GRADE BLADDER CANCER Syed Alam, Dharamainder Choudhary, Garrett Dancik, Carol Pilbeam, and John Taylor Syed AlamSyed Alam More articles by this author , Dharamainder ChoudharyDharamainder Choudhary More articles by this author , Garrett DancikGarrett Dancik More articles by this author , Carol PilbeamCarol Pilbeam More articles by this author , and John TaylorJohn Taylor More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.2421AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES G1P3 is a mitochondrial-membrane protein induced by Type I interferons. It has been shown to have anti-apoptotic properties in several cancers through suppression of cytochrome C release and inhibition of caspase function. G1P3 was found to be differentially overexpressed 15-fold in high grade cisplatin-resistant compared to cisplatin-sensitive patient tumors profiled by laser capture microdissection-coupled microarray. We sought to explore the role of G1P3 in bladder cancer cell lines and to determine its potential as a novel marker of cisplatin-resistance. METHODS Online microarray databases were used to assess expression levels in other bladder cancer datasets. Bladder cancer cell lines (HTB4, HTB5, HTB9, UMUC3) were cultured in defined media. Total RNA was extracted and qPCR performed. Transient transfections with G1P3 gene-specific siRNAs were performed. Cell cycle and apoptosis analyses were performed using flow cytometry and cell viability assays were performed via XTT. Clonogenic assays were performed using a crystal violet dye. RESULTS The microarray datasets in the Oncomine database revealed 3-8 fold increase in G1P3 expression in invasive vs. superficial bladder cancer. Prognostic analysis using the Bladder Cancer Biomarker Evaluation Tool (BC-BET) showed a hazard ratio of >2.80 for survival of patients in the top 50% of G1P3 expression versus the bottom 50%. G1P3 mRNA expression was detected in UMUC3, HTB4, and HTB9. Expression increased 1.7-fold in HTB9 and 1.6-fold in UMUC3 following cisplatin treatment. Knockdown of G1P3 expression by siRNA transfection in UMUC3 and HTB9 cells resulted in a 4.2% and 15% increase in total apoptotic cells following cisplatin (3 µM) treatment for 48 h. Cell cycle analysis of cisplatin treated UMUC3 and HTB9 cells revealed increased numbers of growth arrested S-phase cells - 4.9% and 28.4%, respectively. However, G1P3 knockdown did not significantly alter cisplatin-induced cell cycle changes. Further, compared to mock transfected UMUC3 cells, G1P3 knockdown resulted in decreased cell viability, and it prevented HTB9 colony growth. CONCLUSIONS G1P3 may play a role in cisplatin-resistance and proliferation in bladder cancer cells through suppression of apoptotic pathways. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e1129-e1130 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Syed Alam More articles by this author Dharamainder Choudhary More articles by this author Garrett Dancik More articles by this author Carol Pilbeam More articles by this author John Taylor More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

High tolerance of symbiotic larvae of Pocillopora damicornis to thermal stress.

When coral planulae, which use a horizontal mode of symbiont transmission, are inoculated with Symbiodinium, they suffer greater oxidative stress under strong light or high-temperature stress than non-symbiotic counterparts. Thus, dinoflagellate symbionts may become a source of reactive oxygen species (ROS) under stress. However, it remains unknown whether vertically transmitted symbionts negatively affect coral larvae under stress. We investigated the thermal tolerance of symbiotic planulae of a vertical transmitter coral, Pocillopora damicornis. P. damicornis larvae, which have a large number of symbionts, survived the high-temperature treatment (32 °C) for 2 weeks. Significant reductions in Symbiodinium cell density were observed, but these did not lead to increased mortality of planulae during the 2-week experimental period. Although no significant difference was detected in the percentage of apoptotic cells between temperature treatment groups, pre-bleaching larvae exposed to 31 °C tended to exhibit higher percentages of apoptotic (TUNEL-positive) cells in the gastrodermis than 32 °C-treated larvae, which contained reduced numbers of Symbiodiniumcells. Symbiotic larvae of P. damicornis survived well under high-temperature conditions, although their Symbiodinium cell density decreased. This suggests that P. damicornis larvae have the capacity to reduce the symbiont cell density without a harmful effect on their survivorship under thermal stress. Further studies on antioxidant systems and possible suppression of apoptotic pathways are necessary to elucidate the mechanism underlying the high thermal tolerance of symbiotic larvae of P.damicornis.

Platelet-derived growth factor (PDGF)-C inhibits neuroretinal apoptosis in a murine model of focal retinal degeneration

Platelet-derived growth factor (PDGF)-C is a member of the PDGF family and is critical for neuronal survival in the central nervous system. We studied the possible survival and antiapoptotic effects of PDGF-C on focal retinal lesions in Ccl2−/−/Cx3cr1−/− on C57BL/6N [Crb1rd8] (DKO rd8) background mice, a model for progressive and focal retinal degeneration. We found no difference in transcript and protein expression of PDGF-C in the retina between DKO rd8 mice and wild type (WT, C57BL/6N). Recombinant PDGF-CC protein (500 ng/eye) was injected intravitreally into the right eye of DKO rd8 mice with phosphate-buffered saline as controls into the left eye. The retinal effects of PDGF-C were assessed by fundoscopy, ocular histopathology, A2E levels, apoptotic molecule analysis, and direct flat mount retinal vascular labeling. We found that the PDGF-CC-treated eyes showed slower progression or attenuation of the focal retinal lesions, lesser photoreceptor and retinal pigment epithelial degeneration resulting in better-preserved photoreceptor structure. Lower expression of apoptotic molecules was detected in the PDGF-CC-treated eyes than in controls. In addition, no retinal neovascularization was observed after PDGF-CC treatment. Our results demonstrate that PDGF-C potently ameliorates photoreceptor degeneration via the suppression of apoptotic pathways without inducing retinal angiogenesis. The protective effects of PDGF-C suggest a novel alternative approach for potential age-related retinal degeneration treatment.

Protective effects of melittin on tumor necrosis factor-α induced hepatic damage through suppression of apoptotic pathway and nuclear factor-kappa B activation.

Melittin, a major polypeptide in honeybee venom, have been used to treat inflammatory disease. Various studies have demonstrated the anti-bacterial, anti-viral, anti-inflammatory and anticancer effects of bee venom and melittin. However, the precise mechanism of melittin in liver disease is not yet known. Apoptosis contributes to liver inflammation and fibrosis. Knowledge of the apoptotic mechanisms is important to develop new and effective therapies for treatment of cirrhosis. In the present study, we investigated the anti-apoptotic effect of melittin on tumor necrosis factor (TNF)-α/actinomycin (Act) D-induced apoptosis in hepatocytes. Our results show significant protection from DNA damage by melittin treatment compared with corresponding TNF-α/Act D-treated hepatocytes without melittin. Melittin inhibited TNF-α/Act D-induced activation of the caspase, bcl-2 family of proteins and poly ADP-ribose polymerase (PARP)-1. Our results also indicate that melittin decreased nuclear factor-kappa B (NF-κB) by degradation of phosphorylation of IκB kinase (p-IKK) and NF-κB DNA binding activity in TNF-α/Act D-treated hepatocytes. These results suggest that melittin possesses a potent suppressive effect on apoptotic responses in TNF-α/Act D-treated hepatocytes via the NF-κB pathway.

Resveratrol Exacerbates Both Autoimmune and Viral Models of Multiple Sclerosis

The polyphenol compound resveratrol is reported to have multiple functions, including neuroprotection, and no major adverse effects have been reported. Although the neuroprotective effects have been associated with sirtuin 1 activation by resveratrol, the mechanisms by which resveratrol exerts such functions are a matter of controversy. We examined whether resveratrol can be neuroprotective in two models of multiple sclerosis: experimental autoimmune encephalomyelitis (EAE) and Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD). EAE was induced in C57BL/6 mice, which were fed a control diet or a diet containing resveratrol during either the induction or effector phase or through the whole course of EAE. SJL/J mice were infected with TMEV and fed a control diet or a diet containing resveratrol during the chronic phase of TMEV-IDD. In EAE, all groups of mice treated with resveratrol had more severe clinical signs than the control group. In particular, resveratrol treatment during the induction phase resulted in the most severe EAE, both clinically and histologically. Similarly, in the viral model, the mice treated with resveratrol developed significantly more severe TMEV-IDD than the control group. Thus, surprisingly, the resveratrol treatment significantly exacerbated demyelination and inflammation without neuroprotection in the central nervous system in both models. Our findings indicate that caution should be exercised in potential therapeutic applications of resveratrol in human inflammatory demyelinating diseases, including multiple sclerosis.

Cardioprotective properties of Crataegus oxycantha extract against ischemia-reperfusion injury

The aim of the study was to investigate the cardioprotective effect and mechanism of Crataegus oxycantha (COC) extract, a well-known natural antioxidant-based cardiotonic, against ischemia/reperfusion (I/R) injury. Electron paramagnetic resonance studies showed that COC extract was capable of scavenging superoxide, hydroxyl, and peroxyl radicals, in vitro. The cardioprotective efficacy of the extract was studied in a crystalloid perfused heart model of I/R injury. Hearts were subjected to 30min of global ischemia followed by 45min of reperfusion. During reperfusion, COC extract was infused at a dose rate of 1mg/ml/min for 10min. Hearts treated with COC extract showed a significant recovery in cardiac contractile function, reduction in infarct size, and decrease in creatine kinase and lactate dehydrogenase activities. The expressions of xanthine oxidase and NADPH oxidase were significantly reduced in the treated group. A significant upregulation of the anti-apoptotic proteins Bcl-2 and Hsp70 with simultaneous downregulation of the pro-apoptotic proteins cytochrome c and cleaved caspase-3 was observed. The molecular signaling cascade including phospho-Akt (ser-473) and HIF-1alpha that lead to the activation or suppression of apoptotic pathway also showed a significant protective role in the treatment group. No significant change in phospho-p38 levels was observed. The results suggested that the COC extract may reduce the oxidative stress in the reperfused myocardium, and play a significant role in the inhibition of apoptotic pathways leading to cardioprotection.

Anti-Apoptotic Effect of Hyperbaric Oxygen Preconditioning on a Rat Model of Myocardial Infarction

In our previous study, it was indicated that hyperbaric oxygen preconditioning (HOP) could induce a preconditioning against myocardial infarction and promote neovascularization. In this study, attempts were made to investigate whether a modified short-term pre-exposure protocol could also induce cardioprotection, and its potential mechanisms. Adult male Sprague Dawley rats were divided into seven groups; group 1 was sham surgery (SHAM) and group 2 was pre-exposed to normal air (CTL), and the other groups to HOP 1, 6, 24, 48, and 72 h (H1, H6, H24, H48, H72 groups) before permanent ischemia. The infarct size was measured by triphenyltetrazolium chloride staining, and left ventricular function parameters were recorded. The extent of apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive staining. Caspase-3 activity, Bcl-2, and Bax expression were also measured. Compared with CTL group, myocardial infarct size was significantly decreased as well as cardiac cell apoptosis in area at risk zones (AAR) in H48 group. Meanwhile, the activity of caspase 3 was reduced, the ratio of Bcl-2/Bax expression was up-regulated, and the heart function parameters, including left ventricular systolic pressure (LVSP), left ventricular diastolic pressure (LVEDP), +(dP/dt)(max), and -(dP/dt)(max) were also significantly improved after preconditioning in H48 group. The results indicate that short-term HOP could induce cardioprotection and may not last for more than 24 h. HOP prevents myocardium from permanent ischemia injury by suppression of apoptotic pathways.

SiRNA based strategies for inhibition of apoptotic pathways in vivo—analytical and therapeutic implications

Apoptosis is a genetically controlled mechanism of cell death which is important for embryogenesis, metamorphosis, tissue homeostasis and tumor regression of multicellular organisms. In normal cells as well as in transformed cells signals released from the cytoplasm and/or the cell membrane can trigger the activation of caspases which in turn cleave many cellular substrates, leading to the characteristic morphology of apoptosis. Systematic analysis and dissection of apoptotic pathways was obtained by the use of knock out or transgenic organisms, expressing dominant active or negative proteins. The use of antisense oligonucleotides (ASO) for analysis of apoptotic pathways was commonly restricted to cultured cells, because of the low efficacy of ASO in in vivo experiments. In order to investigate the contribution of specific apoptotic pathways in the onset and maintenance of disease in vivo experiments are needed. This approach allows the analysis of apoptotic pathways within their physiological/pathophysiological environment. The combination of recent advances in in vivo gene delivery with siRNA technique for efficient gene silencing provides new, unique possibilities to study apoptotic pathways thereby evaluating new molecular therapeutic strategies in vivo. In this minireview we will focus on the use of RNA interference for analytical and therapeutical suppression of apoptotic pathways in vivo with special consideration of the liver.