Apoptosis-resistant Phenotype Research Articles

Influence of estrogen on right ventricular mitochondrial function in pulmonary hypertension

There is a female predominance in pulmonary arterial hypertension (PAH) with a ~4:1 female-to-male ratio. However, female PAH patients exhibit better right ventricular (RV) function and thus better survival than the males. The majority of the current PAH therapies target pulmonary vascular remodeling and/or vasoconstriction in the pulmonary vasculature. However, no therapies directly target the RV, partially because the underlying mechanisms of RV failure in PAH are not fully understood. Since the RV serves as the main determinant of mortality, clarifying the mechanism of RV failure and the associated sex differences in PAH may promote the development of novel therapeutic strategies. Numerous molecular abnormalities have been detected in RV in PAH, particularly due to the suppression of mitochondrial function, including the inhibition of glucose oxidation and a shift to uncoupled aerobic glycolysis (Warburg metabolism) and excessive mitochondrial fission. The mitochondrial suppression is associated with hypocontractility and increased apoptosis in RV cardiomyocytes, and the hyperproliferative, pro-fibrotic, and apoptosis-resistant phenotypes in RV fibroblasts in PAH. Mitochondria also serve as the site for sex steroid synthesis, and in turn, the sex steroids, particularly estradiol (E2), influence the mitochondria both indirectly and directly. It is not well understood how E2 affects mitochondrial function in RV in PAH. Hence, this review focuses on the key mitochondrial genes and proteins that are influenced by PAH, E2, and sex.

Endothelial PHD2 deficiency induces apoptosis resistance and inflammation via AKT activation and AIP1 loss independent of HIF2α.

In hypoxic and pseudohypoxic rodent models of pulmonary hypertension (PH), hypoxia-inducible factor (HIF) inhibition attenuates disease initiation. However, HIF activation alone, due to genetic alterations or use of inhibitors of prolyl hydroxylase domain (PHD) enzymes, has not been definitively shown to cause PH in humans, indicating the involvement of other mechanisms. Given the association between endothelial cell dysfunction and PH, the effects of pseudohypoxia and its underlying pathways were investigated in primary human lung endothelial cells. PHD2 silencing or inhibition, while activating HIF2α, induced apoptosis-resistance and IFN/STAT activation in endothelial cells, independent of HIF signaling. Mechanistically, PHD2 deficiency activated AKT and ERK, inhibited JNK, and reduced AIP1 (ASK1-interacting protein 1), all independent of HIF2α. Like PHD2, AIP1 silencing affected these same kinase pathways and produced a similar dysfunctional endothelial cell phenotype, which were partially reversed by AKT inhibition. Consistent with these in vitro findings, AIP1 protein levels in lung endothelial cells were decreased in Tie2-Cre/Phd2 knockout mice compared to wild-type controls. Lung vascular endothelial cells from patients with pulmonary arterial hypertension (PAH) showed IFN/STAT activation. Lung tissue from both SU5416/hypoxia PAH rats and PAH patients all showed AKT activation and dysregulated AIP1 expression. In conclusion, PHD2 deficiency in lung vascular endothelial cells drives an apoptosis-resistant and inflammatory phenotype, mediated by AKT activation and AIP1 loss independent of HIF signaling. Targeting these pathways, including PHD2, AKT, and AIP1, holds potential for developing new treatments for endothelial dysfunction in PH.

Enhanced glycolysis causes extracellular acidification and activates acid-sensing ion channel 1a in hypoxic pulmonary hypertension.

In pulmonary hypertension (PHTN), a metabolic shift to aerobic glycolysis promotes a hyperproliferative, apoptosis-resistant phenotype in pulmonary arterial smooth muscle cells (PASMC). Enhanced glycolysis induces extracellular acidosis, which can activate proton-sensing membrane receptors and ion channels. We previously reported activation of the proton-gated cation channel, acid-sensing ion channel 1a (ASIC1a), contributes to the development of hypoxic PHTN. Therefore, we hypothesize that enhanced glycolysis and subsequent acidification of the PASMC extracellular microenvironment activates ASIC1a in hypoxic PHTN. We observed decreased oxygen consumption rate and increased extracellular acidification rate in PASMC from chronic hypoxia (CH)-induced PHTN rats, indicating a shift to aerobic glycolysis. Additionally, we found that intracellular alkalization and extracellular acidification occur in PASMC following CH, and in vitro hypoxia, which was prevented by inhibition of glycolysis with 2-deoxy-D-glucose (2-DG). Inhibiting H+transport/secretion through carbonic anhydrase IX, Na+/H+ exchanger 1, or vacuolar-type H+-ATPase did not prevent this pH shift following hypoxia. Although the putative monocarboxylate transporter 1 (MCT1) and -4 (MCT4) inhibitor, syrosingopine, prevented the pH shift; the specific MCT1 inhibitor, AZD3965, and/or the MCT4 inhibitor, VB124, were without effect, suggesting syrosingopine targets the glycolytic pathway independent of H+ export. Furthermore, 2-DG and syrosingopine prevented enhanced ASIC1a-mediated store-operated Ca2+ entry in PASMC from CH rats. These data suggest multiple H+ transport mechanisms contribute to extracellular acidosis and inhibiting glycolysis, rather than specific H+ transporters, more effectively prevents extracellular acidification and ASIC1a activation. Together, these data reveal a novel pathologic relationship between glycolysis and ASIC1a activation in hypoxic PHTN.

Lung decellularized matrix-derived 3D spheroids: Exploring silicosis through the impact of the Nrf2/Bax pathway on myofibroblast dynamics

Silicosis is an occupational respiratory disease caused by long-term inhalation of high concentrations of free silica particles. Studies suggest that oxidative stress is a crucial initiator of silicosis fibrosis, and previous studies have linked the antioxidative stress transcription factor known as Nrf2 to fibrosis antagonism. Myofibroblasts play a pivotal role in tissue damage repair due to oxidative stress. Unlike physiological repair, myofibroblasts in fibrosis exhibit an apoptosis-resistant phenotype, continuously synthesising and secreting significant amounts of collagen and other extracellular matrices, which could be a direct cause of silicosis fibrosis. However, the relationship and mechanism of action between oxidative stress and myofibroblast apoptosis resistance remain unclear. In this study, a new 3D cell culture model using mice lung decellularised matrix particles and fibroblasts was developed, simulating the changes in myofibroblasts during the development of silicotic nodules. Western Blot results indicate that silica stimulation leads to increased collagen deposition and decreased apoptosis-related protein Bax and oxidative stress-related protein Nrf2 in the 3D spheroid model. Immunofluorescence experiments reveal co-localisation in their expression. In Nrf2 overexpressing spheroids, Bax exhibits significant upregulation. In the Nrf2 knockout spheroids, Bax is also significantly downregulated; after intervention with Bax inhibitors, a significant downregulation of Bax-induced apoptosis was also detected in the Nrf2-overexpressed spheroids. In contrast, Bax-induced apoptosis showed a significant upregulation trend in Nrf2-overexpressed spheroids after intervention with Bax agonists. The results demonstrate that the spheroid model can mimic the development process of silicotic nodules, and silica stimulation leads to an apoptosis-resistant phenotype in myofibroblasts in the model, acting through the Nrf2/Bax pathway. This research establishes a new methodology for silicosis study, identifies therapeutic targets for silicosis, and opens new avenues for studying the mechanisms of silicosis fibrosis.

PAI-1 deficiency drives pulmonary vascular smooth muscle remodeling and pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by vasoconstriction and remodeling of small pulmonary arteries (PAs). Central to the remodeling process is a switch of pulmonary vascular cells to a proliferative, apoptosis-resistant phenotype. Plasminogen activator inhibitors-1 and -2 (PAI-1 and PAI-2) are the primary physiological inhibitors of urokinase-type and tissue-type plasminogen activators (uPA and tPA), but their roles in PAH are unsettled. Here, we report that: 1) PAI-1, but not PAI-2, is deficient in remodeled small PAs and in early-passage PA smooth muscle and endothelial cells (PASMCs and PAECs) from subjects with PAH compared with controls; 2) PAI-1-/- mice spontaneously develop pulmonary vascular remodeling associated with upregulation of mTORC1 signaling, pulmonary hypertension (PH), and right ventricle (RV) hypertrophy; and 3) pharmacological inhibition of uPA in human PAH PASMCs suppresses proproliferative mTORC1 and SMAD3 signaling, restores PAI-1 levels, reduces proliferation, and induces apoptosis in vitro, and prevents the development of SU5416/hypoxia-induced PH and RV hypertrophy in vivo in mice. These data strongly suggest that downregulation of PAI-1 in small PAs promotes vascular remodeling and PH due to unopposed activation of uPA and consequent upregulation of mTOR and transforming growth factor-β (TGF-β) signaling in PASMCs, and call for further studies to determine the potential benefits of targeting the PAI-1/uPA imbalance to attenuate and/or reverse pulmonary vascular remodeling and PH.NEW & NOTEWORTHY This study identifies a novel role for the deficiency of plasminogen activator inhibitor (PAI)-1 and resultant unrestricted uPA activity in PASMC remodeling and PH in vitro and in vivo, provides novel mechanistic link from PAI-1 loss through uPA-induced Akt/mTOR and TGFβ-Smad3 upregulation to pulmonary vascular remodeling in PH, and suggests that inhibition of uPA to rebalance the uPA-PAI-1 tandem might provide a novel approach to complement current therapies used to mitigate this pulmonary vascular disease.

Pharmacological Agents and Potential New Therapies in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by an imbalance between vasoactive mediators, which causes vascular remodeling, increased pulmonary vascular resistance, and right ventricular overload, ultimately leading to heart failure and death. A metabolic theory has been suggested to explain the pathophysiology of PAH whereby abnormalities in mitochondrial biogenesis can trigger a hyperproliferative and apoptosis-resistant phenotype in cardiopulmonary and malignant cells, leading to mitochondrial dysfunction, which in turn causes the Warburg effect. This can culminate in the mitophagy of pulmonary vessels and cardiomyocytes. The present narrative review focuses on the pathophysiology of PAH, the pharmacological agents currently available for its treatment, and promising and challenging areas of therapeutic investigation.

Adaptation to mechanical stresses drives an apoptosis-resistant and invasive phenotype in liver cells

Adaptation to mechanical stresses drives an apoptosis-resistant and invasive phenotype in liver cells

Fatty Acid Oxidation Promotes Apoptotic Resistance and Proinflammatory Phenotype of CD4+ Tissue-resident Memory T cells in Crohn’s Disease

Background and aimsAs the most abundant memory T cells and major source of tumor necrosis factor α (TNF-α) in the intestinal mucosa of Crohn’s disease (CD) patients, CD4+ tissue-resident memory T (TRM) cells play a critical role in CD pathogenesis. We investigated the role of metabolic reprogramming in the regulation of proinflammatory and apoptosis-resistant phenotype for CD4+ TRM cells. MethodsCD4+ TRM cells were collected from intestinal resection tissues from control and CD patients. Transcriptomic and metabolomic analysis were performed to identify metabolic characteristics of CD4+ TRM cells. ELISA and qPCR experiments were utilized to assess cytokines level in CD4+ TRM cells, activation-induced cell apoptosis (AICD) rate was evaluated by flow cytometry. Transwell assay and wound healing assay were performed to detect the effect of CD4+ TRM cells on the migration of normal intestinal epithelial cells. ResultsTranscriptomic data combined with unbiased metabolomic analysis revealed an increased fatty acid oxidation (FAO) phenotype existed in CD4+ TRM cells from CD patients. The lipidomic data and stable isotope tracer experiments demonstrated that CD4+ TRM cells upregulated their lipid lipolysis and fatty acid uptake to fuel FAO in CD patients. Mechanistically, the activated NF-κB signaling increased transcription of genes involved in lipid lipolysis, fatty acid uptake and oxidation in CD4+ TRM cells from CD patients. Targeting FAO of CD4+ TRM cells reversed their apoptosis-resistant and proinflammatory phenotype in CD Patients. ConclusionCD4+ TRM cells process an accelerated FAO mediated by activated NF-κB signaling in CD patients, targeting FAO could reverse their apoptosis-resistant and proinflammatory phenotype. These findings shed a new light on the pathogenic mechanism investigation and novel therapy development in CD patients.

Disruption of extracellular redox balance drives persistent lung fibrosis and impairs fibrosis resolution

Lung fibrosis is a devastating outcome of various diffuse parenchymal lung diseases. Despite rigorous research efforts, the mechanisms that propagate its progressive and nonresolving nature remain enigmatic. Oxidative stress has been implicated in the pathogenesis of lung fibrosis. However, the role of extracellular redox state in disease progression and resolution remains largely unexplored. Here, we show that compartmentalized control over extracellular reactive oxygen species (ROS) by aerosolized delivery of recombinant extracellular superoxide dismutase (ECSOD) suppresses an established bleomycin-induced fibrotic process in mice. Further analysis of publicly available microarray, RNA-seq and single-cell RNAseq datasets reveals a significant decrease in ECSOD expression in fibrotic lung tissues that can be spontaneously restored during fibrosis resolution. Therefore, we investigate the effect of siRNA-mediated ECSOD depletion during the established fibrotic phase on the self-limiting nature of the bleomycin mouse model. Our results demonstrate that in vivo knockdown of ECSOD in mouse fibrotic lungs impairs fibrosis resolution. Mechanistically, we demonstrate that transforming growth factor (TGF)-β1 downregulates endogenous ECSOD expression, leading to the accumulation of extracellular superoxide via Smad-mediated signaling and the activation of additional stores of latent TGF-β1. In addition, depletion of endogenous ECSOD during the fibrotic phase in the bleomycin model induces an apoptosis-resistant phenotype in lung fibroblasts through unrestricted Akt signaling. Taken together, our data strongly support the critical role of extracellular redox state in fibrosis persistence and resolution. Based on these findings, we propose that compartment-specific control over extracellular ROS may be a potential therapeutic strategy for managing fibrotic lung disorders.

A large-scale Boolean model of the rheumatoid arthritis fibroblast-like synoviocytes predicts drug synergies in the arthritic joint

Rheumatoid arthritis (RA) is a complex autoimmune disease with an unknown aetiology. However, rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS) play a significant role in initiating and perpetuating destructive joint inflammation by expressing immuno-modulating cytokines, adhesion molecules, and matrix remodelling enzymes. In addition, RA-FLS are primary drivers of inflammation, displaying high proliferative rates and an apoptosis-resistant phenotype. Thus, RA-FLS-directed therapies could become a complementary approach to immune-directed therapies by predicting the optimal conditions that would favour RA-FLS apoptosis, limit inflammation, slow the proliferation rate and minimise bone erosion and cartilage destruction. In this paper, we present a large-scale Boolean model for RA-FLS that consists of five submodels focusing on apoptosis, cell proliferation, matrix degradation, bone erosion and inflammation. The five-phenotype-specific submodels can be simulated independently or as a global model. In silico simulations and perturbations reproduced the expected biological behaviour of the system under defined initial conditions and input values. The model was then used to mimic the effect of mono or combined therapeutic treatments and predict novel targets and drug candidates through drug repurposing analysis.

Nicotinamide N-methyltransferase mediates lipofibroblast–myofibroblast transition and apoptosis resistance

Metabolism controls cellular phenotype and fate. In this report, we demonstrate that nicotinamide N-methyltransferase (NNMT), a metabolic enzyme that regulates developmental stem cell transitions and tumor progression, is highly expressed in human idiopathic pulmonary fibrosis (IPF) lungs, and is induced by the pro-fibrotic cytokine, transforming growth factor-β1 (TGF-β1) in lung fibroblasts. NNMT silencing reduces the expression of extracellular matrix proteins, both constitutively and in response to TGF-β1. Furthermore, NNMT controls the phenotypic transition from homeostatic, pro-regenerative lipofibroblasts to pro-fibrotic myofibroblasts. This effect of NNMT is mediated, in part, by the downregulation of lipogenic transcription factors, TCF21 and PPARγ, and the induction of a less proliferative but more differentiated myofibroblast phenotype. NNMT confers an apoptosis-resistant phenotype to myofibroblasts that is associated with the downregulation of pro-apoptotic members of the Bcl-2 family, including Bim and PUMA. Together, these studies indicate a critical role for NNMT in the metabolic reprogramming of fibroblasts to a pro-fibrotic and apoptosis-resistant phenotype and support the concept that targeting this enzyme may promote regenerative responses in chronic fibrotic disorders such as IPF.

Acid-sensing ion channel 1a regulates mitochondrial membrane potential and pulmonary arterial smooth muscle cell apoptosis

Acid-sensing ion channel 1a (ASIC1a) is a proton-gated cation channel that contributes to the development of chronic hypoxia (CH)-induced pulmonary hypertension (PH). Our prior studies demonstrate that ASIC1a is expressed in pulmonary arterial smooth muscle cells (PASMCs) and contributes to plasmalemmal membrane potential ( E m ) depolarization and augmented intracellular Ca 2+ signaling leading to enhanced vasoconstrictor reactivity and vascular remodeling. During PH, mitochondrial dysfunction associated with mitochondrial membrane potential (Δψm) hyperpolarization can inhibit opening of the mitochondrial permeability transition pore (mPTP), thereby repressing apoptosis and promoting the hyperproliferative and apoptosis-resistant PASMC phenotype. Recent evidence suggests that ASIC1a is localized to mitochondria and regulates the mPTP. However, it is unknown if mitochondrial-localized ASIC1a (mtASIC1a) contributes to the pathogenesis of PH. Therefore, the overall objective of this study is to determine the functional role of mtASIC1a in the apoptosis-resistant PASMC phenotype associated with PH. We hypothesized that CH causes Δψm hyperpolarization and apoptosis-resistance in PASMCs due to loss of mtASIC1a localization. To test this hypothesis, we housed Asic1a knockout ( Asic1a -/- ) and wild-type ( Asic1a +/+ ) mice in a hypobaric chamber (barometric pressure: ~380 mmHg) for 4 weeks to induce PH. Following CH, we found increased expression of ASIC1a at the plasma membrane and decreased expression in mitochondria, which were associated with PASMC E m depolarization and Δψm hyperpolarization. Using tetramethylrhodamine (TMRE) fluorescence to measure Δψm, we found that TMRE fluorescence was significantly increased (p=0.02) in PASMCs from normoxic Asic1a -/- mice compared to Asic1a +/+ mice, indicating that deletion of Asic1a leads to Δψm hyperpolarization. We utilized a lentiviral vector encoding mitochondrial-targeted human ASIC1a (mtASIC1a LV) to overexpress mtASIC1a in PASMCs (p=0.003) and found that transduction with mtASIC1a LV in PASMCs from Asic1a -/- mice significantly decreased TMRE fluorescence (p=0.004), further supporting the functional role of mtASIC1a to regulate Δψm. To assess apoptosis, we measured levels of active caspase-3 by western blot analysis in intrapulmonary arteries (PAs) from Asic1a +/+ and Asic1a -/- mice following CH. CH decreased levels of active caspase-3 in PAs from Asic1a +/+ (p=0.032), but not Asic1a -/- mice. Under normoxic conditions, active caspase-3 was lower in PAs from Asic1a -/- compared to Asic1a +/+ mice (p=0.044). These data suggest mtASIC1a plays an important role in the regulation of Δψm and that the loss of mtASIC1a contributes to Δψm hyperpolarization and apoptosis resistance in PASMCs following CH. Future studies will examine the contributions of mtASIC1a to the pathogenesis of PH through the regulation of mitochondrial reactive oxygen species, mitochondrial Ca 2+ levels, mPTP sensitivity, and mitochondrial dynamics. NIH R01 HL111084 to N.L. Jernigan and NIH T32 HL007736 to T.C. Resta This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 150: Targeting The Lipogenic Enzyme ATP Citrate Lyase As A Potential Therapy Against Coronary Artery Disease

Introduction: Coronary artery disease (CAD) such as coronary stenosis and intra vein graft stenosis are characterized by a cancer-like pro-proliferative and apoptosis-resistant phenotype of smooth muscle cells (SMCs), fueled by a metabolic shift toward glycolysis and interconnected global changes in the epigenetic landscape. The nucleo-cytoplasmic enzyme ATP Citrate Lyase (ACLY) has recently emerged as a key player and therapeutic target in cancer by favoring Warburg effect, lipid synthesis and chromatin remodeling. However, its role in CAD is still unknown. We hypothesized that ACLY is upregulated in CAD and supports the abnormal phenotype of CAD-CoASMCs. Methods and Results: ACLY expression positively correlates with vascular remodeling (aSMA labeling) in human distal coronary artery (CoAs, p<0,01) as well as in dog saphenous vein (SV) graft from bypass surgery (p<0,05). Increased expression and activation (phosphorylation) of ACLY were also observed in CoASMCs isolated from CAD patients (immunoblot, p<0,01) with preferential localization in the nucleus (immunofluorescence ACLY labelling (p<0,001)). Pharmacological (BMS303141) or molecular (siRNA) ACLY inhibition resulted in decreased survival, proliferation (immunoblot: PCNA, MCM2 and SURVIVIN (p<0,05) & immunofluorescence Ki67 and Annexin V labelling (p<0,001)), histones acetylation (immunoblot: acH3K27 and acH4 (p<0,05)) and reversed Warburg effect (immunoblot: pPDH, LDHA, PFKBP3 (p<0,01) & seahorse assays (p<0,05)) of CAD-CoASMC. RNA sequencing analysis showed that ACLY molecular inhibition in CAD-CoASMC mostly affectes cell cycle and cell proliferation pathways. Ex-vivo, ACLY inhibition attenuates vascular remodeling (EVG staining) in human CoAs and SVs rings denuded of endothelial cells and exposed to growth factors (p<0,05). In vivo, SMS-targeted loss of Acly in mice model of carotid artery denudation injury prevents vascular remodeling (p<0,05). Same results are observed with pharmacological inhibition of ACLY (BMS303141 & bempedoic acid) in carotid artery wire injury rat model (p<0,05). Conclusion: We demonstrated that ACLY is implicated in vascular remodeling in CAD and its Pharmacological inhibition may represent a novel avenue as therapeutic treatment.

Abstract 3813: Role of CDKN2B antisense RNA 1 in Epstein-Barr virus associated gastric carcinoma

Abstract Background: Epstein-Barr Virus (EBV)-associated gastric carcinoma (GC) (EBVaGC) is a subtype of GC which represents approximately 10% of this tumor. CDKN2B antisense RNA 1 (CDKN2B-AS1) is a long non-coding RNA associated with chronic diseases like cardiovascular disease and cancer. This study aimed to evaluate if the loss of CDKN2B-AS1 shifted the balance of the competing endogenous RNA (ceRNA) networks favoring an apoptosis resistant phenotype through ebv-miR-BART4-5p/BID in EBVaGC. Material and Methods: Seven gastric cancer cell lines were used to determine the expression of CDKN2B-AS1. Specific cell lines were used for CDKN2B-AS1 inhibition assays, the transfection of ebv-miR-BART4-5p and the binding between CDKN2B-AS1 and ebv-miR-BART4-5p. The detection of BID protein was determined by Western Blot. To validate the in vitro results, we detected CDKN2B-AS1, BID, and ebv-miR-BART4-5p expression levels by RT-qPCR in four EBVaGC positive and five negative cases. Apoptosis was detected by in situ hybridization (ISH). Results and Discussion: CDKN2B-AS1 is expressed at higher levels in NCI-N87 and SNU-1 cell lines and at lower levels in AGS and KATO-III. A significant decrease in BID protein expression was observed after co-transfection with ebv-miR-BART4-5p and CDKN2B-AS1 inhibitor. However, these results were not significant at mRNA level. The luciferase assay validated the predicted binding between ebv-miR-BART4-5p and CDKN2B-AS1. In EBVaGC samples, a significant decrease in BID expression and cleaved caspase-3 in the presence of miR-BART4-5p was observed. Our results show that decreasing CDKN2B-AS1 expression favors viral miR binding on BID mRNAs through ceRNA networks. Also, these results could explain why positive EBVaGCs have lower apoptosis rate than EBVaGC negative cases. Grant support: ANID/FONDECYT/POSTDOCTORADO/3201028, CONICYT-FONDAP-15130011, FONDECYT-1191928 Citation Format: Keila Torres, Wilda Olivares, Gonzalo Carrasco, Andres Rodriguez, Alejandro H. Corvalan. Role of CDKN2B antisense RNA 1 in Epstein-Barr virus associated gastric carcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3813.

Discovery of the ARP2 protein as a determining molecule in tumor cell death.

Cancer is a multifactorial disease that constitutes a serious public health problem worldwide. Prostate cancer advanced stages are associated with the development of androgen-independent tumors and an apoptosis-resistant phenotype that progresses to metastasis. By studying androgen-independent lymphoid nodule carcinoma of the prostate (LNCaP) cells induced to apoptosis by serum elimination, we identified the activation of a non-selective cationic channel of 23pS conductance that promotes incoming Ca2+ currents, as well as apoptosis final stages. arp2cDNA was isolated and identified to be of the same cell type, and mRNA was expressed in Xenopus laevis oocytes, which was found to be associated with the activation of incoming Ca2+ currents and induction to apoptosis. cDNA, which encodes the ARP2 protein, was overexpressed in LNCaP cells and Chinese hamster ovary cells, which induced apoptosis. Our evidence suggests that protein ARP2 overexpression and transit to the cell membrane allows an increased Ca2+ incoming current that initiates the apoptosis process in epithelial-type cells whose phenotype shows resistance to programmed cell death.

Anti-inflammatory effects of PRIMA-1MET (mutant p53 reactivator) induced by inhibition of nuclear factor-κB on rheumatoid arthritis fibroblast-like synoviocytes.

Fibroblast-like synoviocytes (FLSs), the main pathological cells in rheumatoid arthritis (RA), display tumor-like phenotype, including hyper-proliferation, apoptosis resistance, and aggressive phenotype. Excessive proliferation and insufficient apoptosis of RA-FLSs can lead to hyperplastic synovial pannus tissue, excess production of inflammatory mediators, and destruction of joints. In this article, we investigate the effect of PRIMA-1MET on the apoptosis induction and inhibition of pro-inflammatory cytokines in RA-FLSs. Synovial tissue samples were obtained from 10 patients with RA. The FLSs were treated with different concentrations of PRIMA-1MET. The rate of apoptosis and cell survival was assessed by flow cytometry and MTT assay and Real-time quantitative PCR was performed to evaluate the transcription of p53, IL-6, IL-1β, TNF-α, Noxa, p21, PUMA, Bax, Survivin, and XIAP in treated RA-FLSs. The protein level of p53, IκBα, and phospho-IκBα were measured using Western blotting. The results showed that PRIMA-1MET induced apoptosis in RA-FLSs and increased significantly the expression of Noxa, and decreased significantly IL-6, IL-1β, p53, and phospho-IκBα expression. PRIMA-1MET can induce apoptosis in RA-FLSs through induction of Noxa expression while p53 was downregulated. Furthermore, PRIMA-1MET treatment results in the suppression of pro-inflammatory cytokine production and NF-κB inhibition. Given the role of p53 and NF-κB in RA-FLSs, PRIMA-1MET can be considered as a new therapeutic strategy for rheumatoid arthritis.

Abstract 15005: Tlr4/py14-Caveolin-1-Mediated Endothelial C-iap2 Expression During Schistosomiasis-Associated Pulmonary Arterial Hypertension

Introduction: During schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH), hyperproliferation of abnormal endothelial cells (ECs) contributes to development of severe vascular lesions within the lungs; a life-threatening phenomenon that remains with no target therapy. Hypothesis: Here, we found that antigenic molecules from the major etiological agent of Sch-PAH, i.e., S. mansoni , amplify the secretion of the antiapoptotic protein c-IAP2 via TLR4-pY14Cav-1 signaling pathway, which we hypothesized to contribute to generation of an EC memory of survival and severity of PAH. Methods/Results: Cav-1 deficiency via shedding of extracellular vesicles (EVs) leads to survival of an apoptosis-resistant EC phenotype during idiopathic PAH. Similarly, S. mansoni egg antigens also reduced lung EC-Cav-1 expression, suggesting that Cav-1 also plays a role during pathogen-associated PAH. Cav-1 depletion via EVs precedes its phosphorylation at residue Tyr14 (pY14Cav-1), which in turn, contributes to EV loading. Among apoptotic regulators, IAPs have been found as a cargo of EVs in different conditions, including in TLR4-activated cells. Accordingly, our data indicates that S. mansoni egg antigen p40 also activated TLR4/NFkB-mediated signaling, inducing c-IAP2 expression and a time-dependent phosphorylation of Cav-1 in human lung microvascular EC (HMVEC-L: 228.2 +/- 38.28% of control; p<0.05; n=4). Moreover, although Sm-p40 alone was unable to induce shedding of EVs, combination with NFkB-associated proinflammatory mediators (TNF-α, IL-6, and ATP), significantly increased EV shedding by HMVEC-L, suggesting that S. mansoni may epigenetically prime ECs, but co-factors are required to induce EV shedding. Finally, Sch-PAH model using EC- Cav1 -/- mice ( End-scl.Cre ERT2 ;Rosa mt/mg ;Cav1 fl/fl ) revealed that Cav-1 absence led to accumulation of eggs within the lungs and loss of eGFP+ cells, indicating that EC-Cav-1 phosphorylation may be required to development of Sch-PAH. Conclusions: Our data suggest that S. mansoni -induced pY14Cav-1 is associated to expression of the anti-apoptotic c-IAP2 protein, which may be critical for prolonged survival of a pathogenic EC phenotype during the development of Sch-PAH.

Cancer and apoptosis: The apoptotic activity of plant and marine natural products and their potential as targeted cancer therapeutics.

Cancer is a multifactorial, multi-stage disease, including complex cascades of signaling pathways—the cell growth governed by dysregulated and abrupt cell division. Due to the complexity and multi-regulatory cancer progression, cancer is still a challenging disease to treat and survive. The screening of extracts and fractions from plants and marine species might lead to the discovery of more effective compounds for cancer therapeutics. The isolated compounds and reformed analogs were known as future prospective contenders for anti-cancer chemotherapy. For example, Taxol, a potent mitotic inhibitor discovered from Taxus brevifolia, suppresses cell growth and arrest, induces apoptosis, and inhibits proliferation. Similarly, marine sponges show remarkable tumor chemo preventive and chemotherapeutic potential. However, there is limited research to date. Several plants and marine-derived anti-cancer compounds having the property to induce apoptosis have been approved for clinical trials. The anti-cancer activity kills the cell and slows the growth of cancer cells. Among cell death mechanisms, apoptosis induction is a more profound mechanism of cell death triggered by naturally isolated anti-cancer agents. Evading apoptosis is the major hurdle in killing cancer cells, a mechanism mainly regulated as intrinsic and extrinsic. However, it is possible to modify the apoptosis-resistant phenotype of the cell by altering many of these mechanisms. Various extracts and fractions successfully induce apoptosis, cell-cycle modulation, apoptosis, and anti-proliferative activity. Therefore, there is a pressing need to develop new anti-cancer drugs of natural origins to reduce the effects on normal cells. Here, we’ve emphasized the most critical elements: i) A better understanding of cancer progression and development and its origins, ii) Molecular strategies to inhibit the cell proliferation/Carcino-genesis, iii) Critical regulators of cancer cell proliferation and development, iv) Signaling Pathways in Apoptosis: Potential Targets for targeted therapeutics, v) Why Apoptosis induction is mandatory for effective chemotherapy, vi) Plants extracts/fractions as potential apoptotic inducers, vii) Marine extracts as Apoptotic inducers, viii) Marine isolated Targeted compounds as Apoptotic inducers (FDA Approved/treatment Phase). This study provides a potential therapeutic option for cancer, although more clinical studies are needed to verify its efficacy in cancer chemotherapy.

Abstract 5607: Combining PD-1 inhibition with the TRAIL receptor agonist TLY012 promotes pancreatic ductal adenocarcinoma tumor regression in an immunocompetent mouse model

Abstract Introduction: An immunosuppressed, apoptosis-resistant phenotype characterizes pancreatic ductal adenocarcinoma (PDAC). Both inflammation and tumorigenesis are influenced by the Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL) pathway. TLY012 is pegylated recombinant TRAIL protein and is an orphan drug for systemic sclerosis and chronic pancreatitis. The potential synergy between TLY012 and anti-mouse PD-1 antibody was investigated in a syngeneic immunocompetent heterotopic mouse model. Methods: KPC-luc PDAC cells were subcutaneously implanted into C57Bl/6 mice. Treatment combined 10 mg/kg TLY012 three times per week with 10 mg/kg anti-mouse PD-1 antibody twice weekly and were compared to individual treatment and control groups. Cytokine profiling via 32-plex Luminex immunoassay was completed after 7 days and after three months of treatment. Flow cytometry at three months evaluated NK and T cell profiles in the spleen and tumors. Results: PDAC tumor-bearing mice treated with the combination of anti-mouse PD-1 and TLY012 had slower tumor growth and reduced tumor volume at 70 days compared to either drug alone (all p<0.005). B-cell activating factor, which can be a marker of PDAC tumor progression, was decreased in single and dual treatment groups at three months of treatment. This factor showed the earliest decrease in the dual treatment group, with a cytokine level 44% of that of control mice at 7 days. Long-term dual treatment mice also had the highest levels of proinflammatory cytokines interferon gamma (average 5.6 times control level, p=0.046), CCL5 (average 14.1 times control level, p=0.048), and interleukin-3 (IL-3, average 71.1 times control level, p=0.0053). Flow cytometry showed trends toward decreased circulating regulatory T cells, increased NK cells, and a higher proportion of CD8+ T cells within tumors in the dual treatment group. Conclusions: The combination of anti-mouse PD-1 and TLY012 prevents growth of PDAC in an immunocompetent mouse model. The combination also increases tumor-infiltrating CD8+ T cells, decreases circulating Treg cells and alters cytokine expression. CCL5 is a T-cell chemokine, and both interferon gamma and IL-3 are produced by activated T cells and macrophages, and have proinflammatory, antitumor effects. Combining TLY012 and anti-mouse PD-1 creates these changes in immune cell and cytokine levels, suggesting induction of a more proinflammatory immune environment. The proinflammatory state may contribute to decreased tumor growth. Citation Format: Anna D. Louie, Kelsey E. Huntington, Young Lee, Jared Mompoint, Jinxuan Wu, Seulki Lee, Wafik S. El-Deiry. Combining PD-1 inhibition with the TRAIL receptor agonist TLY012 promotes pancreatic ductal adenocarcinoma tumor regression in an immunocompetent mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5607.

Decoy receptor 2 mediates the apoptosis-resistant phenotype of senescent renal tubular cells and accelerates renal fibrosis in diabetic nephropathy

Apoptotic resistance leads to persistent accumulation of senescent cells and sustained expression of a senescence-associated secretory phenotype, playing an essential role in the progression of tissue fibrosis. However, whether senescent renal tubular epithelial cells (RTECs) exhibit an apoptosis-resistant phenotype, and the role of this phenotype in diabetic nephropathy (DN) remain unclear. Our previous study was the first to demonstrate that decoy receptor 2 (DcR2) is associated with apoptotic resistance in senescent RTECs and renal fibrosis. In this study, we aimed to further explore the mechanism of DcR2 in apoptosis-resistant RTECs and renal fibrosis in DN. DcR2 was co-localized with fibrotic markers (α-SMA, collagen IV, fibronectin), senescent marker p16, and antiapoptotic proteins FLIP and Bcl2 but rarely co-localized with caspase 3 or TUNEL. DcR2 overexpression promoted renal fibrosis in mice with streptozotocin (STZ)-induced DN, as evidenced by augmented Masson staining and upregulated expression of fibrotic markers. DcR2 overexpression also enhanced FLIP expression while reducing the expression of pro-apoptotic proteins (caspases 8 and 3) in senescent RTECs, resulting in apoptotic resistance. In contrast, DcR2 knockdown produced the opposite effects in vitro and in vivo. Moreover, quantitative proteomics and co-immunoprecipitation experiments demonstrated that DcR2 interacted with glucose-related protein 78 kDa (GRP78), which has been shown to promote apoptotic resistance in cancer. GRP78 exhibited co-localization with senescent and antiapoptotic markers but was rarely co-expressed with caspase 3 or TUNEL. Additionally, GRP78 knockdown decreased the apoptosis resistance of HG-induced senescent RTECs with upregulated cleaved caspase 3 and increased the percentage of apoptotic RTECs. Mechanistically, DcR2 mediated apoptotic resistance in senescent RTECs by enhancing GRP78–caspase 7 interactions and promoting Akt phosphorylation. Thus, DcR2 mediated the apoptotic resistance of senescent RTECs and renal fibrosis by interacting with GRP78, indicating that targeting the DcR2–GRP78 axis represents a promising therapeutic strategy for DN.