Death Receptors DR5 Research Articles

Loss of p53 Impairs Death Receptor Expression and Confers Resistance to CD19 CAR T Cell Therapy in BCP-ALL

Loss of p53 function predicts a dismal outcome in relapsed B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Chimeric antigen receptor T cell (CAR T) therapy was recently approved to salvage relapsed/refractory BCP-ALL. We observed a significantly worse overall survival after CD19-targeting CAR T therapy in children with TP53-mutated (TP53Mut) compared to TP53-wildtype (TP53WT) BCP-ALL. To investigate the effect of p53 loss on CAR T therapy response, we modelled TP53 mutations in two BCP-ALL cell lines and observed resistance to CAR T upon p53 loss. Moreover, expression analysis in cell lines and xenografts demonstrated that loss of p53 abrogates expression of the death receptors Fas and DR5, both implicated in CAR T cytotoxicity. Conversely, ectopic expression of Fas improved CAR T cytotoxicity. Furthermore, p53 stabilization induced expression of both Fas and DR5, accompanied by increased CAR T-mediated killing. While these findings provide mechanistic insight as to why CAR T therapy fails against TP53Mut BCP-ALL, they may also provide opportunities to enhance the efficacy of CAR T treatment both in patients with TP53Mut and TP53WT BCP-ALL. Furthermore, these data underscore the need of alternative curative therapies for this very high-risk patient group.

A DR4, DR5 Targeting Conjugated TRAIL Treatment for Colorectal Carcinogenesis: A Way to Future?

TRAIL or tumor necrosis factor-related apoptosis-inducing ligand has been one of the major frontiers for the chemotherapeutic approach to treating carcinogenesis. Despite the emergence of TRAIL resistance cancer cell lines, it has been extensively studied for its unique property to induce apoptosis and provide specificity to any other conjugated chemotherapeutic agent. TRIAL highly reduces the dose and increases specific and targeted action against the cancer cells. It is a specific agonist for the death receptors DR4 and DR5 present on the cancer cell surface. Normal cells have more expression of decoy type of death receptors, which makes the use of TRAIL safer for regular cells. The TRAIL-drug conjugate systems have been under the radar due to their possible high synergistic potential and may open the door for the future cancer-specific targeted treatment frontier. This current study was conducted with a particular aim to provide a concise and simple amalgamation of current scenarios of different conjugations of this molecule along with various other molecules, RNAs, ligands, and anticancer drugs. Along with possible delivery systems of TRIAL that can have a significant future and the promise that is held by this particular way of cancer combinational chemotherapy with special interest in colorectal cancer.

The Association of Death Receptors and TGF-β1 Expression in Urothelial Bladder Cancer and Their Prognostic Significance.

Death receptor signalization that triggers the extrinsic apoptotic pathway and TGF-β1 have important roles in urothelial carcinogenesis, with a complex interplay between them. The aim of this research was to assess the association of death receptors DR4, DR5, and FAS as well as TGF-β1 immunohistochemical expression with the clinicopathological characteristics of urothelial bladder cancer (UBC) and to evaluate their prognostic significance. The decrease or loss of death receptors' expression was significantly associated with muscle-invasive tumors, while non-invasive UBC often retains the expression of death receptors, which are mutually strongly linked. High DR4 expression is a marker of low-grade tumors and UBC associated with exposition to known carcinogens. Conversely, TGF-β1 was significantly associated with high tumor grade and advanced stage. High expression of DR4 and FAS indicates longer overall survival. High TGF-β1 signifies an inferior outcome and is an independent predictor of adverse prognosis in UBC patients. This study reveals the expression profile of death receptors in UBC and their possible interconnection with TGF-β1 and indicates independent prognostic significance of high FAS and TGF-β1 expression in UBC, which may contribute to deciphering the enigma of UBC heterogeneity in light of the rapid development of novel and effective therapeutic approaches, including targeting of the TRAIL-induced apoptotic pathway.

Transfected SARS-CoV-2 spike DNA for mammalian cell expression inhibits p53 activation of p21(WAF1), TRAIL Death Receptor DR5 and MDM2 proteins in cancer cells and increases cancer cell viability after chemotherapy exposure.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and COVID-19 infection has led to worsened outcomes for patients with cancer. SARS-CoV-2 spike protein mediates host cell infection and cell-cell fusion that causes stabilization of tumor suppressor p53 protein. In-silico analysis previously suggested that SARS-CoV-2 spike interacts with p53 directly but this putative interaction has not been demonstrated in cells. We examined the interaction between SARS-CoV-2 spike, p53 and MDM2 (E3 ligase, which mediates p53 degradation) in cancer cells using an immunoprecipitation assay. We observed that SARS-CoV-2 spike protein interrupts p53-MDM2 protein interaction but did not detect SARS-CoV-2 spike bound with p53 protein in the cancer cells. We further observed that SARS-CoV-2 spike suppresses p53 transcriptional activity in cancer cells including after nutlin exposure of wild-type p53-, spike-expressing tumor cells and inhibits chemotherapy-induced p53 gene activation of p21(WAF1), TRAIL Death Receptor DR5 and MDM2. The suppressive effect of SARS-CoV-2 spike on p53-dependent gene activation provides a potential molecular mechanism by which SARS-CoV-2 infection may impact tumorigenesis, tumor progression and chemotherapy sensitivity. In fact, cisplatin-treated tumor cells expressing spike were found to have increased cell viability as compared to control cells. Further observations on γ-H2AX expression in spike-expressing cells treated with cisplatin may indicate altered DNA damage sensing in the DNA damage response pathway. The preliminary observations reported here warrant further studies to unravel the impact of SARS-CoV-2 and its various encoded proteins including spike on pathways of tumorigenesis and response to cancer therapeutics. More efforts should be directed at studying the effects of the SARS-CoV-2 spike and other viral proteins on host DNA damage sensing, response and repair mechanisms. A goal would be to understand the structural basis for maximal anti-viral immunity while minimizing suppression of host defenses including the p53 DNA damage response and tumor suppression pathway. Such directions are relevant and important including not only in the context of viral infection and mRNA vaccines in general but also for patients with cancer who may be receiving cytotoxic or other cancer treatments.

Abstract 3173: Impact of hypoxia on the integrated stress response activated by imipridones ONC201 and ONC206 in pediatric diffuse midline glioma cells

Abstract Diffuse midline gliomas (DMGs) are highly aggressive, high-grade gliomas which typically arise in children and young adults. With currently approved treatments the median survival from time of diagnosis for pediatric DMG is 8-10 months with only 10% of children living to 2 years post diagnosis. Despite being only 15% of the cases it makes up 40% of the pediatric brain cancer deaths making it the leading cause of death for all pediatric glioma cases. Two recent clinical studies, NCT03416530 and NCT03134131, have shown the clinical efficacy of Dordaviprone (ONC201/TIC10) for the treatment of DMG; increasing median survival to 22 months in patients following radiation treatment prior to recurrence. Imipridone ONC206, a chemical derivative of ONC201, is under clinical development for treatment of pediatric and adult patients with primary brain tumors (NCT04732065 and NCT04541082). To further improve treatment, we must continue to study how the tumor microenvironment impacts the efficacy of imipridones. One crucial aspect of all brain cancers is hypoxia, so the IC50s of the SU-DIGP-25, SU-DIPG-XIII and SU-DIPGIV pediatric DMG cell lines treated with ONC201 or ONC206 were measured using the CellTiter-Glo assay under conditions of hypoxia and normoxia. Imipridones mediate apoptosis through the upregulation of the TRAIL death receptor DR5 and the activation of the integrated stress response (ISR), so western blots were used to show changes in the ISR protein expression in ONC201 treated DMG cells at multiple different degrees of hypoxia. To understand how hypoxia inducible factors (HIFs) play a role in resistance and susceptibility to ONC201 or ONC206, HIF-1a, HIF-2a, and HIF-3a were knocked down showing altered ISR protein expression after treating with the imipridones under hypoxic and normoxic conditions. Citation Format: Tyler J. Roady, Nolan Stubbs, Josephine Chen, Yutong Xia, Ashley Sanchez Sevilla Uruchurtu, Xiaobing Tian, Lanlan Zhou, Wafik S. El-Deiry. Impact of hypoxia on the integrated stress response activated by imipridones ONC201 and ONC206 in pediatric diffuse midline glioma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3173.

Non-oxidized and oxidized flaxseed orbitides differently induce HepG2 cell apoptosis: involvement of cellular uptake and membrane death receptor DR4.

Flaxseed orbitides have health-promoting properties, particularly potent anti-cancer activity. However, flaxseed orbitides containing a methionine structure, such as [1-9-NαC]-linusorb B2 (CLB), are easily oxidized to sulfoxide ([1-9-NαC],[1-Rs,Ss-MetO]-linusorb-B2 (CLC)) and sulfone ([1-9-NαC], [1-MetO]-linusorb B2 (CLK)), with CLC having less anti-cancer ability than CLB. It is unclear why oxidized flaxseed orbitides are less effective against cancer than non-oxidized flaxseed orbitide. Non-oxidized ([1-9-NαC]-linusorb-B3 (CLA) and CLB) and oxidized (CLC and CLK) flaxseed orbitides were found to significantly upregulate the levels of pro-apoptotic proteins, including Bax/Bcl-2, CytoC, caspase-3, and caspase-8, in a dose-dependent manner, with non-oxidized flaxseed orbitides being more effective than oxidized flaxseed orbitides. Mechanically, the cellular absorption of non-oxidized flaxseed orbitides was higher than that of oxidized flaxseed orbitides. Moreover, the significant fluorescence quenching of DR4 protein by flaxseed orbitides (especially non-oxidized orbitides) indicated the formation of a DR4-orbitide complex. Molecular docking demonstrated that non-oxidized orbitides could easily dock into the active cavity of DR4 protein. Further blocking DR4 significantly reduced the ability of non-oxidized flaxseed orbitides to stimulate caspase-3 expression, whereas oxidized flaxseed orbitides retained this ability. Non-oxidized flaxseed orbitides are more effective against cancer than oxidized flaxseed orbitides due to higher cellular uptake and activation of the DR4-mediated death receptor signaling pathway. © 2024 Society of Chemical Industry.

Employing Piezoelectric Mg2+-Doped Hydroxyapatite to Target Death Receptor-Mediated Necroptosis: A Strategy for Amplifying Immune Activation.

Although immunogenic cell death (ICD) inducers evidently enhance the effectiveness of immunotherapy, their potential is increasingly restricted by the development of apoptosis resistance in tumor cells, poor immunogenicity, and low T-cell immune responsiveness. In this study, for the first time, piezoelectrically catalyzed Mg2+-doped hydroxyapatite (Mg-HAP) nanoparticles, which are coated with a mesoporous silica layer and loaded with ONC201 as an agonist to specifically target the death receptor DR5 on tumor cells, ultimately developing an Mg-HAP@MS/ONC201 nanoparticle (MHMO NP) system, are engineered. Owing to its excellent piezoelectric properties, MHMO facilitates the release of a significant amount of reactive oxygen species and Ca2+ within tumor cells, effectively promoting the upregulation of DR5 expression and inducing tumor cell necroptosis to ultimately overcome apoptosis resistance. Concurrently, Mg2+ released in the tumor microenvironment promotes CD8+ T receptor activation in response to the antitumor immune reaction induced by ICD. Using RNA-seq analysis, it is elucidated that MHMO can activate the NF-κB pathway under piezoelectric catalysis, thus inducing M1-type macrophage polarization. In summary, a dual-targeting therapy system that targets both tumor cells and the tumor microenvironment under piezoelectric catalysis is designed. This system holds substantial potential for advancements in tumor immunotherapy.

Amyloid Beta Oligomers Activate Death Receptors and Mitochondria-Mediated Apoptotic Pathways in Cerebral Vascular Smooth Muscle Cells; Protective Effects of Carbonic Anhydrase Inhibitors.

Amyloid beta (Aβ) deposition within the brain vasculature is an early hallmark of Alzheimer's disease (AD), which triggers loss of brain vascular smooth muscle cells (BVSMCs) in cerebral arteries, via poorly understood mechanisms, altering cerebral blood flow, brain waste clearance, and promoting cognitive impairment. We have previously shown that, in brain endothelial cells (ECs), vasculotropic Aβ species induce apoptosis through death receptors (DRs) DR4 and DR5 and mitochondria-mediated mechanisms, while FDA-approved carbonic anhydrase inhibitors (CAIs) prevent mitochondria-mediated EC apoptosis in vitro and in vivo. In this study, we analyzed Aβ-induced extrinsic and intrinsic (DR- and mitochondria-mediated) apoptotic pathways in BVSMC, aiming to unveil new therapeutic targets to prevent BVSMC stress and death. We show that both apoptotic pathways are activated in BVSMCs by oligomeric Aβ42 and Aβ40-Q22 (AβQ22) and mitochondrial respiration is severely impaired. Importantly, the CAIs methazolamide (MTZ) and acetazolamide (ATZ) prevent the pro-apoptotic effects in BVSMCs, while reducing caspase 3 activation and Aβ deposition in the arterial walls of TgSwDI animals, a murine model of cerebral amyloid angiopathy (CAA). This study reveals new molecular targets and a promising therapeutic strategy against BVSMC dysfunction in AD, CAA, and ARIA (amyloid-related imaging abnormalities) complications of recently FDA-approved anti-Aβ antibodies.

AICAR Induces AMPK-Independent Cell Death in Adult T-Cell Leukemia/Lymphoma and Has Anti-Tumor Activity

Introduction: Adult T-cell leukemia/lymphoma (ATL) is an aggressive T cell leukemia/lymphoma caused by human T-cell lymphotropic virus type I (HTLV-1) and has a poor outcome. Recently, we reported that AMPKα, the catalytic unit of AMP-activated protein kinase (AMPK), is highly expressed in cells from patients with ATL and that an AMPK inhibitor had anti-tumor activity in ATL mice 1. On the other hand, acadesine or 5-aminoimidazole-4-carboxamide riboside (AICAR) is anAMPK activator, and was recently shown to have tumor suppressive effects on B cell chronic lymphocytic leukemia via the activation of AMPK. However, the effect of AICAR on the death of ATL-related cell lines is unknown. This study evaluated the effects of AICAR on death in ATL-related cell lines and its anti-tumor activity. Results: We demonstrated that AICAR inhibited the proliferation of ATL-related cell lines (S1T, MT-1 and MT-2) but not non-HTLV-1-infected Jurkat cells and peripheral blood mononuclear cells from healthy individuals. However, AICAR did not increase the phosphorylation levels of AMPKα. We found that AICAR increased annexin V-positive cell numbers in the sub-G0/G1 phase, and decreased the mitochondrial membrane potential and caspase-3/8/9 activation, which are hallmarks of apoptosis. However, AICAR did not increase the phosphorylation levels of AMPKα. On the other hand, HTLV-1 Tax, an HTLV-1-encoded oncogenic factor, expression did not affect AICAR-induced cell death. Moreover, AICAR induced the expression of death receptors (DR) DR4 and DR5 in vitro. Furthermore, AICAR inhibited the growth and infiltration of S1T cells transplanted subcutaneously in NOD/SCID/gamma mice. Conclusion: This is the first evidence to demonstrate the AMPK-independent effects of AICAR on death in ATL-related cell lines and its anti-tumor activity. Thus, AICAR might be a candidate for the treatment of ATL. Disclosures : No relevant conflicts of interest to declare. 1. Aikawa A, Kozako T, Uchida Y, et al. Cell death induced by dorsomorphin in adult T-cell leukemia/lymphoma is AMPK-independent. Febs j. 2020;287(18):4005-4015.

Anti-tumor activity of 5-aminoimidazole-4-carboxamide riboside with AMPK-independent cell death in human adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T cell leukemia/lymphoma caused by human T-cell lymphotropic virus type I (HTLV-1). Acadesine or 5-aminoimidazole-4-carboxamide riboside (AICAR) is an AMP-activated protein kinase (AMPK) activator that was recently shown to have tumor suppressive effects on B cell chronic lymphocytic leukemia, but not ATL. This study evaluated the cytotoxic effects of AICAR on ATL-related cell lines and its anti-tumor activity. Here, we demonstrated that AICAR induced cell death via apoptosis and the mitochondrial membrane depolarization of ATL-related cell lines (S1T, MT-1, and MT-2) but not non-HTLV-1-infected Jurkat cells. However, AICAR did not increase the phosphorylation levels of AMPKα. In addition, AICAR increased the expression of the death receptors (DR) DR4 and DR5, and necroptosis-related proteins including phosphorylated receptor-interacting protein family members and the mixed lineage kinase domain-like protein. Interestingly, HTLV-1 Tax, an HTLV-1-encoded oncogenic factor, did not affect AICAR-induced apoptosis. Furthermore, AICAR inhibited the growth of human ATL tumor xenografts in NOD/SCID/gamma mice in vivo. Together, these results suggest that AICAR induces AMPK-independent cell death in ATL-related cell lines and has anti-tumor activity, indicating that it might be a therapeutic agent for ATL.

Insight into the crystal structure analysis, vibrational studies, reactivities (MESP, HOMO-LUMO, NBO), and the anticancer activities of ruthenium diazide [Ru(POP)(PPh3)(N3)2] complex by molecular docking approach

This present work employs experimental and density functional theory (DFT) computations methods to investigate the structural, electronic, molecular interactions, and molecular docking of a ruthenium diazide [Ru(POP)(PPh3)(N3)2] complex with potential applications in apoptosis regulation. Crystallography analysis was conducted using Hirshfeld surface analysis which illustrated diverse intermolecular and intramolecular interactions, such as C H…O and CC….H respectively. Also, the following interactions and their percentage abundance existed in the complex O…H 1.5 %, C…H 19.9 %, H…H 68.8 %, C…N 0.2 % and N…H 9.9 %. With H…H interaction showcasing as dominant interaction in the complex. The molecular structure, vibrational analysis, and quantum chemical parameters were investigated within the framework of density functional theory at the ωB97XD/def2svp method. Molecular docking of the Ru-complex with receptor proteins involved in apoptosis regulation, including Death Receptor DR5, Estrogen Receptor Alpha (ERα), and Fas receptor, was performed. Results indicate potential interactions with these proteins, suggesting the Ru-complex's role in caspase-mediated apoptosis, particularly in colon and breast cancer cell lines. The investigation provides valuable insights into the reactivity and potential applications of the Ru-complex in cancer treatment.

TRAIL-dependent apoptosis of peritoneal mesothelial cells by NK cells promotes ovarian cancer invasion

A crucial requirement for metastasis formation in ovarian high-grade serous carcinoma (HGSC) is the disruption of the protective peritoneal mesothelium. Using co-culture systems of primary human cells, we discovered that tumor-associated NK cells induce TRAIL-dependent apoptosis in mesothelial cells via death receptors DR4 and DR5 upon encounter with activated Tcells. Upregulation of TRAIL expression in NK cells concomitant with enhanced cytotoxicity toward mesothelial cells was driven predominantly by T-cell-derived TNFα, as shown by affinity proteomics-based analysis of the Tcell secretome in conjunction with functional studies. Consistent with these findings, we detected apoptotic mesothelial cells in the peritoneal fluid of HGSC patients. In contrast to mesothelial cells, HGSC cells express negligible levels of both DR4 and DR5 and are TRAIL resistant, indicating cell-type-selective killing by NK cells. Our data point to a cooperative action of T and NK in breaching the mesothelial barrier in HGSC patients.

Fn14 and TNFR2 as regulators of cytotoxic TNFR1 signaling.

Tumor necrosis factor (TNF) receptor 1 (TNFR1), TNFR2 and fibroblast growth factor-inducible 14 (Fn14) belong to the TNF receptor superfamily (TNFRSF). From a structural point of view, TNFR1 is a prototypic death domain (DD)-containing receptor. In contrast to other prominent death receptors, such as CD95/Fas and the two TRAIL death receptors DR4 and DR5, however, liganded TNFR1 does not instruct the formation of a plasma membrane-associated death inducing signaling complex converting procaspase-8 into highly active mature heterotetrameric caspase-8 molecules. Instead, liganded TNFR1 recruits the DD-containing cytoplasmic signaling proteins TRADD and RIPK1 and empowers these proteins to trigger cell death signaling by cytosolic complexes after their release from the TNFR1 signaling complex. The activity and quality (apoptosis versus necroptosis) of TNF-induced cell death signaling is controlled by caspase-8, the caspase-8 regulatory FLIP proteins, TRAF2, RIPK1 and the RIPK1-ubiquitinating E3 ligases cIAP1 and cIAP2. TNFR2 and Fn14 efficiently recruit TRAF2 along with the TRAF2 binding partners cIAP1 and cIAP2 and can thereby limit the availability of these molecules for other TRAF2/cIAP1/2-utilizing proteins including TNFR1. Accordingly, at the cellular level engagement of TNFR2 or Fn14 inhibits TNFR1-induced RIPK1-mediated effects reaching from activation of the classical NFκB pathway to induction of apoptosis and necroptosis. In this review, we summarize the effects of TNFR2- and Fn14-mediated depletion of TRAF2 and the cIAP1/2 on TNFR1 signaling at the molecular level and discuss the consequences this has in vivo.

TRAIL promotes the polarization of human macrophages toward a proinflammatory M1 phenotype and is associated with increased survival in cancer patients with high tumor macrophage content.

TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily that can either induce cell death or activate survival pathways after binding to death receptors (DRs) DR4 or DR5. TRAIL is investigated as a therapeutic agent in clinical trials due to its selective toxicity to transformed cells. Macrophages can be polarized into pro-inflammatory/tumor-fighting M1 macrophages or anti-inflammatory/tumor-supportive M2 macrophages and an imbalance between M1 and M2 macrophages can promote diseases. Therefore, identifying modulators that regulate macrophage polarization is important to design effective macrophage-targeted immunotherapies. The impact of TRAIL on macrophage polarization is not known. Primary human monocyte-derived macrophages were pre-treated with either TRAIL or with DR4 or DR5-specific ligands and then polarized into M1, M2a, or M2c phenotypes in vitro. The expression of M1 and M2 markers in macrophage subtypes was analyzed by RNA sequencing, qPCR, ELISA, and flow cytometry. Furthermore, the cytotoxicity of the macrophages against U937 AML tumor targets was assessed by flow cytometry. TCGA datasets were also analyzed to correlate TRAIL with M1/M2 markers, and the overall survival of cancer patients. TRAIL increased the expression of M1 markers at both mRNA and protein levels while decreasing the expression of M2 markers at the mRNA level in human macrophages. TRAIL also shifted M2 macrophages towards an M1 phenotype. Our data showed that both DR4 and DR5 death receptors play a role in macrophage polarization. Furthermore, TRAIL enhanced the cytotoxicity of macrophages against the AML cancer cells in vitro. Finally, TRAIL expression was positively correlated with increased expression of M1 markers in the tumors from ovarian and sarcoma cancer patients and longer overall survival in cases with high, but not low, tumor macrophage content. TRAIL promotes the polarization of human macrophages toward a proinflammatory M1 phenotype via both DR4 and DR5. Our study defines TRAIL as a new regulator of macrophage polarization and suggests that targeting DRs can enhance the anti-tumorigenic response of macrophages in the tumor microenvironment by increasing M1 polarization.

XPO1 inhibition sensitises CLL cells to NK cell mediated cytotoxicity and overcomes HLA-E expression

The first-in-class inhibitor of exportin-1 (XPO1) selinexor is currently under clinical investigation in combination with the BTK inhibitor ibrutinib for patients with chronic lymphocytic leukaemia (CLL) or non-Hodgkin lymphoma. Selinexor induces apoptosis of tumour cells through nuclear retention of tumour suppressor proteins and has also recently been described to modulate natural killer (NK) cell and T cell cytotoxicity against lymphoma cells. Here, we demonstrate that XPO1 inhibition enhances NK cell effector function against primary CLL cells via downregulation of HLA-E and upregulation of TRAIL death receptors DR4 and DR5. Furthermore, selinexor potentiates NK cell activation against CLL cells in combination with several approved treatments; acalabrutinib, rituximab and obinutuzumab. We further demonstrate that lymph node associated signals (IL-4 + CD40L) inhibit NK cell activation against CLL cells via upregulation of HLA-E, and that inhibition of XPO1 can overcome this protective effect. These findings allow for the design of more efficacious combination strategies to harness NK cell effector functions against CLL.

AKT inhibition interferes with the expression of immune checkpoint proteins and increases NK-induced killing of HL60-AML cells.

To determine the role of the AKT pathway in the regulating of natural Killer-induced apoptosis of acute myeloid leukemia cells and to characterize the associated molecular mechanisms. BALB/c nude mice were injected with HL60 cells to induce a xenogenic model of subcutaneous leukemic tumors. Mice were treated with perifosine, and their spleens were analyzed using biometry, histopathology, and immunohistochemistry. Gene expression analysis in leukemia cells was performed by real-time PCR. Protein analysis of leukemia and natural Killer cells was performed by flow cytometry. AKT inhibition in HL60 cells, followed by co-culture with natural Killer cells was performed to assess cytotoxicity. Apoptosis rate was quantified using flow cytometry. Perifosine treatment caused a reduction in leukemic infiltration in the spleens of BALB/c nude mice. In vitro , AKT inhibition reduced HL60 resistance to natural Killer-induced apoptosis. AKT inhibition suppressed the immune checkpoint proteins PD-L1, galectin-9, and CD122 in HL60 cells, but did not change the expression of their co-receptors PD1, Tim3, and CD96 on the natural Killer cell surface. In addition, the death receptors DR4, TNFR1, and FAS were overexpressed by AKT inhibition, thus increasing the susceptibility of HL60 cells to the extrinsic pathway of apoptosis. The AKT pathway is involved in resistance to natural Killer-induced apoptosis in HL60 cells by regulating the expression of immune suppressor receptors. These findings highlight the importance of AKT in contributing to immune evasion mechanisms in acute myeloid leukemia and suggests the potential of AKT inhibition as an adjunct to immunotherapy.

The Role of TRAIL in Apoptosis and Immunosurveillance in Cancer

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily that selectively induces apoptosis in tumor cells without harming normal cells, making it an attractive agent for cancer therapy. TRAIL induces apoptosis by binding to and activating its death receptors DR4 and DR5. Several TRAIL-based treatments have been developed, including recombinant forms of TRAIL and its death receptor agonist antibodies, but the efficacy of TRAIL-based therapies in clinical trials is modest. In addition to inducing cancer cell apoptosis, TRAIL is expressed in immune cells and plays a critical role in tumor surveillance. Emerging evidence indicates that the TRAIL pathway may interact with immune checkpoint proteins, including programmed death-ligand 1 (PD-L1), to modulate PD-L1-based tumor immunotherapies. Therefore, understanding the interaction between TRAIL and the immune checkpoint PD-L1 will lead to the development of new strategies to improve TRAIL- and PD-L1-based therapies. This review discusses recent findings on TRAIL-based therapy, resistance, and its involvement in tumor immunosurveillance.

Recent Advances in the Development of Nanodelivery Systems Targeting the TRAIL Death Receptor Pathway

The TRAIL (TNF-related apoptosis-inducing ligand) apoptotic pathway is extensively exploited in the development of targeted antitumor therapy due to TRAIL specificity towards its cognate receptors, namely death receptors DR4 and DR5. Although therapies targeting the TRAIL pathway have encountered many obstacles in attempts at clinical implementation for cancer treatment, the unique features of the TRAIL signaling pathway continue to attract the attention of researchers. Special attention is paid to the design of novel nanoscaled delivery systems, primarily aimed at increasing the valency of the ligand for improved death receptor clustering that enhances apoptotic signaling. Optionally, complex nanoformulations can allow the encapsulation of several therapeutic molecules for a combined synergistic effect, for example, chemotherapeutic agents or photosensitizers. Scaffolds for the developed nanodelivery systems are fabricated by a wide range of conventional clinically approved materials and innovative ones, including metals, carbon, lipids, polymers, nanogels, protein nanocages, virus-based nanoparticles, dendrimers, DNA origami nanostructures, and their complex combinations. Most nanotherapeutics targeting the TRAIL pathway are aimed at tumor therapy and theranostics. However, given the wide spectrum of action of TRAIL due to its natural role in immune system homeostasis, other therapeutic areas are also involved, such as liver fibrosis, rheumatoid arthritis, Alzheimer's disease, and inflammatory diseases caused by bacterial infections. This review summarizes the recent innovative developments in the design of nanodelivery systems modified with TRAIL pathway-targeting ligands.

Death Receptor DR5 as a Proviral Factor for Viral Entry and Replication of Coronavirus PEDV.

Porcine epidemic diarrhea virus (PEDV), a member of Coronaviridae, causes high mortality in newborn piglets, and has caused significant economic losses in the pig industry. PEDV infection can induce apoptosis, both caspase-dependent and caspase-independent, but the details of apoptosis remain clarified. This study investigated the effect of death receptor DR5 on PEDV infection and its relationship with PEDV-induced apoptosis. We found that DR5 knockdown reduced viral mRNA and protein levels of PEDV, and the viral titer decreased from 104.5 TCID50 to 103.4 TCID50 at 12 hpi. Overexpression of DR5 significantly increased the viral titer. Further studies showed that DR5 facilitates viral replication by regulating caspase-8-dependent apoptosis, and the knockdown of DR5 significantly reduced PEDV-induced apoptosis. Interestingly, we detected a biphasic upregulation expression of DR5 in both Vero cells and piglets in response to PEDV infection. We found that DR5 also facilitates viral entry of PEDV, especially, incubation with DR5 antibody can reduce the PEDV binding to Vero cells. Our study improves the understanding of the mechanism by which PEDV induces apoptosis and provides new insights into the biological function of DR5 in PEDV infection.

Amyloid‐mediated TRAIL DRs activation leads to progressive degeneration of cerebral vascular smooth muscle cells

AbstractBackgroundVascular accumulation of amyloid beta (Ab) leads to loss of vascular smooth muscle cells (VSMC) in cerebral arteries via unknown mechanisms, promoting cerebral blood flow alterations and contributing to cognitive impairment. Ab species with different lengths or mutated familial variants may have differential effects on VSMC. Ab1‐42, the main pathogenic form of amyloid in the AD brain with the highest propensity to form aggregates, increased apoptosis in brain vascular cells whereas Ab1‐40 was found to be less toxic. By comparison, the familial Ab variant E22Q, induced the most cell death of all the amyloid variants tested. However, there has been little progress in defining the pathways leading to VSMC degeneration in AD and related disorders. The aim of this study was to identify Ab‐mediated cell death mechanisms in VSMC.MethodHuman cerebral VSMC were treated with pre‐oligomerized variants of Ab for 2‐8hrs (acute treatment) and 24‐72hrs (chronic treatment). Analysis of fragmented nucleosomes and visualization of cytochrome c (Cyt. C) expression by immunocytochemistry were used to measure apoptosis. Activation of intrinsic and extrinsic apoptotic pathways were examined by western blot and caspase‐glo assays. The effects of Ab on mitochondrial function were examined using a Seahorse XF96 Analyzer and TMRM fluorescent dye in live cells.ResultsAcute Ab treatment in VSMC up‐regulated tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) death receptors DR4 and DR5 with activation of caspase 8 and transient activation of Nuclear Factor k B (NF‐kB). DR4 and DR5 expression remained high with chronic Ab treatment and lead to caspase activation followed by Cyt. C release and apoptosis. 24hrs of Ab treatment also decreased mitochondrial membrane potential and significantly impaired mitochondrial respiration.ConclusionAcute exposure of VSMC to Ab causes up‐regulation and activation of DR4/DR5, that, over time, results in mitochondrial dysfunction, caspase activation and apoptosis. Our data suggests that an early and transient activation of NF‐kB may also contribute to the toxic effects of Ab, possibly by inducing pro‐inflammatory pathways in the neurovascular unit.