Tumor Necrosis Factor-related Apoptosis-inducing Ligand Pathway Research Articles

Abstract 3036: Sensitivity of ONC201/TIC10 cancer therapeutic on neuroendocrine prostate cancer (NEPC) and neuroendocrine differentiation (NED)

Abstract Although androgen deprivation therapy and androgen receptor (AR) blockade are highly effective therapies for metastatic prostate cancer (PCa), most patients develop resistance, leading to castration-resistant prostate cancer (CRPC). A subset of CRPC shows neuroendocrine prostate cancer (NEPC) features, which are associated with poor prognosis and limited therapeutic strategies. NEPC is characterized by oncogenic driver activation and epigenetic changes, partly controlled by transcription factors like BRN2 and SOX2. AR has been shown to suppress BRN2 transcription, which is required for NEPC, and BRN2-dependent regulation of the NEPC marker SOX2 (Bishop et al., 2017). Dordaviprone (ONC201/TIC10) is a first-in-class small molecule that antagonizes DRD2, induces tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), and activates the integrated stress response (ISR). Neuroendocrine tumors express significant DRD2 levels, suggesting ONC201 as a potential therapeutic strategy in NEPC or when drivers for disease progression are overexpressed (OE). PCa cell lines PC3, DU145, LNCaP, and 22RV1 are ONC201 sensitive, with IC50=2.87 μM, 3.18 μM, 1.31 μM, and 1.16 μM, respectively (Ding et al., 2023). To characterize the association of BRN2/SOX2 dysregulation with ONC201 sensitivity, we transiently OE BRN2/SOX2 in PCa. We hypothesized that markers of neuroendocrine differentiation (NED), activation of the ISR, TRAIL, and ClpP and dopamine receptor expression contribute to NEPC cell death and sensitivity to ONC201. We performed CellTiter-Glo experiments to assess viability after 96 hours ± BRN2 OE. DU145 cells with BRN2 OE increased their sensitivity to ONC201 (IC50=2.75 µM) compared to empty vector (IC50=3.03 µM). Colony formation assays were conducted in PCa and analyzed 7 days after ONC201 treatment to show ONC201 effect on PCa cell lines. DU145 was treated at 0.5, 1, and 2 µM of ONC201. There were 95 ± 3.22 colonies for the control group, 83 ± 5.22 colonies with 0.5 µM, 74 ± 3.64 colonies with 1 µM, and 8 ± 2.03 colonies with 2 µM ONC201. DU145 showed a significant reduction in colony-forming ability when treated with 1 and 2 uM ONC201 compared to the control, with P values of <0.05 and <0.0001, respectively. We OE BRN2 and observed changes in NED markers and ISR pathway. In PC3, FoxO1 and ATF4 levels increased. In DU145, FoxO1, ENO2, PGP9.5, CgA, and ATF4 levels decreased. We reveal that DU145 OE at 48 hours does not result in greater expression of NEPC markers. BRN2 OE significantly increased PCa cell sensitivity to ONC201 and was evident without an increase in common phenotypical markers used for NEPC assessment (FoxO1, ENO2, PGP9.5, CgA). Expression change was not shown when PCa had an integral AR pathway. Ongoing efforts are observing ONC201 treatment effects on NED markers and the TRAIL pathway due to BRN2 OE and showing increased sensitivity of PCa to ONC201 with BRN2 OE. Citation Format: Elizabeth C. Ding, Maximilian Pinho-Schwermann, Shengliang Zhang, Connor Purcell, Wafik S. El-Deiry. Sensitivity of ONC201/TIC10 cancer therapeutic on neuroendocrine prostate cancer (NEPC) and neuroendocrine differentiation (NED) [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 3036.

Abstract 4780: TRAIL-inducing imipridone ONC201/TIC10 demonstrates anti-neoplastic effects in colonic adenoma-derived organoids

Abstract Background: Colorectal cancer (CRC) is the second leading cause of cancer-related death inthe United States and screening is the most effective method to reduce mortality. Chemoprevention, which aims to prevent CRC through eradication or prevention of precursor colonic adenomas, represents an alternative strategy to address this problem. The imipridone dordaviprone (ONC201) has been shown to induce apoptosis in cancer cells through both upregulation of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and the integrated stress response. More recently, we have shown that ONC201 induces TRAIL and apoptosis in a dose-dependent manner and reduces adenoma formation in the Apcmin/+ CRC mouse model. We hypothesized that ONC201 would similarly enhance human colonic adenoma cell death through both TRAIL-dependent and TRAIL-independent mechanisms. We therefore evaluated the effects of ONC201 in two adenoma-derived organoid lines: one developed from an adenoma obtained from an individual with familial adenomatous polyposis (FAP) and the second from a sessile serrated adenoma (SSA). Methods: Sensitivity of the FAP and SSA organoid lines to ONC201 was assessed using CellTiter-Glo® luminescent cell viability assay. Organoids were plated in triplicates and treated with ONC201 (concentration ranging from 0 uM to 20 uM). Results were analyzed after 72 hours of incubation. Western blotting was performed on lysates generated from organoids treated with either 1.69 uM DMSO, 1.69 uM ONC201, or 3.38 uM ONC201 for FAP and 1.23 uM DMSO, 1.23 uM ONC201, or 2.46 uM ONC201 for SSA for 0, 24, or 48 hours. Co-culture experiments were performed with the adenoma-derived organoids (dyed using blue CMAC dye) and human NK-92MI cells (dyed with green CMFDA dye) treated with either 845 nM DMSO, 845 nM ONC201, or 1.69 uM ONC201 for FAP and 615 nM DMSO, 615 nM ONC201, or 1.23 uM ONC201 for SSA. Fluorescent images following administration of red live/dead dye were performed using DAPI, FITC, and cherry red channels on ImageXpress® at 0, 24, 48, and 72hours. Results: ONC201 demonstrated antineoplastic effects in adenoma-derived FAP and SSA organoids. Half maximal inhibitory concentrations (IC50) of ONC201 in FAP and SSA organoids were 1.69 uM and 1.23 uM, respectively. As was noted in rodent studies, the mechanism of action of ONC201 appears to be mediated through modulation of multiple pathways including the TRAIL pathway (TRAIL and DR5 were both upregulated) and the integrated stress response (ATF4 was upregulated). Co-culture with NK cells revealed an increase in NK-mediated organoid cell death. The ability of ONC201 to enhance NK-mediated killing is still being evaluated. Further analysis of the effects of ONC201 on stemness markers and on T-cell-mediated organoid cell killing are currently underway and may reveal other potential biomarkers and chemopreventive strategies for ONC201. Citation Format: Alexis J. Lannigan, Jasper Chan, Maximilian Schwermann, Lanlan Zhou, Varun V. Prabhu, Michael Dame, Dean Brenner, Wafik S. El-Deiry, Alexander G. Raufi. TRAIL-inducing imipridone ONC201/TIC10 demonstrates anti-neoplastic effects in colonic adenoma-derived organoids [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 4780.

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.

Abstract 1070: The anti-tumor efficacy of combining oral ATR kinase inhibitor ceralasertib with TIC10/ONC201, an oral Akt/ERK inhibitor, TRAIL pathway and integrated stress response inducer, in prostate cancer treatment

Abstract Prostate cancer is the most common cancer and the second leading cause of cancer death among men in the United States. There are 268,490 estimated new cases and 34,500 estimated deaths in 2022 according to the NIH. Patients with metastatic castration resistant prostate cancer (mCRPC) have a poor prognosis and the current treatment options show limited efficacy. From the TRAP trial, 20% of mCRPC patients are reported to bear DNA repair defects. Ceralasertib, formerly known as AZD6738, is a potent and selective orally bioavailable inhibitor of the ataxia tenlangiectasia and Rad3-related (ATR) kinase, which is involved in DNA repair in response to DNA damage and replication stress. Ceralasertib’s antitumor activity as a monotherapy in treating prostate cancer is moderate. Thus, we investigated a combination therapy of ceralasertib with ONC201, a potent and cytotoxic orally bioavailable inhibitor of the serine/threonine protein kinase Akt and extracellular signal-regulated kinase (ERK). Upon administration, ONC201 can induce tumor cell apoptosis mediated by tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and activate integrated stress response (IRS). Preliminary results demonstrate synergistic activity with the combination therapy in vitro using CellTiterGLO viability assay 72 hours in a 96 well plate post treatment. Ongoing studies using western blotting and cytokine profiling are intended to illustrate the mechanism behind the proven synergy. Our results aim to solve the overarching need in developing novel therapeutic strategies to overcome resistance in current prostate cancer treatments. Citation Format: Yutong Xia, Maximilian P. Schwermann, Andrew George, Anna Ochsner, Benedito A. Carneiro, Wafik S. El-Deiry. The anti-tumor efficacy of combining oral ATR kinase inhibitor ceralasertib with TIC10/ONC201, an oral Akt/ERK inhibitor, TRAIL pathway and integrated stress response inducer, in prostate cancer treatment [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 1070.

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.

Targeting TRAIL Death Receptors in Triple-Negative Breast Cancers: Challenges and Strategies for Cancer Therapy

The tumor necrosis factor (TNF) superfamily member TNF-related apoptosis-inducing ligand (TRAIL) induces apoptosis in cancer cells via death receptor (DR) activation with little toxicity to normal cells or tissues. The selectivity for activating apoptosis in cancer cells confers an ideal therapeutic characteristic to TRAIL, which has led to the development and clinical testing of many DR agonists. However, TRAIL/DR targeting therapies have been widely ineffective in clinical trials of various malignancies for reasons that remain poorly understood. Triple negative breast cancer (TNBC) has the worst prognosis among breast cancers. Targeting the TRAIL DR pathway has shown notable efficacy in a subset of TNBC in preclinical models but again has not shown appreciable activity in clinical trials. In this review, we will discuss the signaling components and mechanisms governing TRAIL pathway activation and clinical trial findings discussed with a focus on TNBC. Challenges and potential solutions for using DR agonists in the clinic are also discussed, including consideration of the pharmacokinetic and pharmacodynamic properties of DR agonists, patient selection by predictive biomarkers, and potential combination therapies. Moreover, recent findings on the impact of TRAIL treatment on the immune response, as well as novel strategies to address those challenges, are discussed.

Abstract PO-064: ONC212 stimulates cytotoxic T-cell killing, increases tumor-immune cell interactions, and promotes tumor regression in combination with TLY012 in a PDAC murine model

Abstract Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and lethal cancer with a 4.2% 5-year survival rate. There is an urgent need for innovative treatments for patients suffering from PDAC. Patients with PDAC often have immunosuppressed tumors that are apoptosis-resistant and have limited immune cell infiltration and/or activation. Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL) selectively induces cancer cell apoptosis during innate immunity, while ONC212 is a potent fluorinated second-generation imipridone currently in IND-enabling studies that induces TRAIL signaling and the integrated stress response (ISR). TLY012 is a novel PEG’ylated trimeric TRAIL receptor agonist being clinically developed to overcome the short half-life of TRAIL. We hypothesized that combining a TRAIL pathway inducer and a TRAIL receptor agonist may be efficacious in PDAC and may activate immune cell killing based on prior work with imipridone ONC201. Immune cell co-culture experiments were conducted using PANC1 PDAC cells and TALL-104 CD8+ cytotoxic T-cells at a 1:1 effector-to-target cell ratio with or without ONC212. We observed a significant increase in T-cell killing of PDAC cells in the co-culture assay following treatment with ONC212 at several doses as compared to controls. We noted an increase in tumor-immune cell interactions as measured by the number of T-cells that were directly touching tumor cells at each timepoint. The BxPC-3 immunodeficient murine PDAC model revealed an increase in natural killer (NK) cell tumor infiltration by immunohistochemistry (IHC) staining for NK1.1 after 30 days of 50 mg/kg ONC212 treatment three times a week. The combination of ONC212 and TLY012 was evaluated using subcutaneously-implanted KPC-Luc PDAC cells in a syngeneic immunocompetent C57BL/6 mouse model. Mice treated with 25 mg/kg ONC212 alone twice a week, 10 mg/kg TLY012 alone twice a week, or combination therapy with ONC212 and TLY012 showed statistically significant decreases in tumor growth compared to controls after 5 weeks of treatment (n=6 mice per treatment condition) by tumor volume and in vivo bioluminescent imaging. We are analyzing murine plasma cytokine profiles, changes in tumor-infiltrating NK- and T-cells by flow cytometric and IHC analysis of murine spleen and KPC-Luc tumor samples. We report a novel immune stimulation of the TRAIL pathway and T-cell activation by ONC212 plus TLY012 leading to cytotoxic anti-PDAC responses in vivo. Citation Format: Kelsey E. Huntington, Anna Louie, Young Lee, Jared Mompoint, Isacco Ferrarini, Aakash Jhaveri, Varun V. Prabhu, Allen Melemed, Seulki Lee, Wafik S. El-Deiry. ONC212 stimulates cytotoxic T-cell killing, increases tumor-immune cell interactions, and promotes tumor regression in combination with TLY012 in a PDAC murine model [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-064.

Dexamethasone induces pancreatic β-cell apoptosis through upregulation of TRAIL death receptor.

Long-term medication with dexamethasone - a synthetic glucocorticoid (GC) drug - results in hyperglycemia, or steroid-induced diabetes. Although recent studies revealed that dexamethasone directly induces pancreatic β-cell apoptosis, its molecular mechanisms remain unclear. In our initial analysis of mRNA transcripts, we discovered the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) pathway may be involved in dexamethasone-induced pancreatic β-cell apoptosis. In the present study, a mechanism of dexamethasone-induced pancreatic β-cell apoptosis through the TRAIL pathway was investigated in cultured cells and isolated mouse islets. INS-1 cells were cultured with and without dexamethasone in the presence or absence of a glucocorticoid receptor (GR) inhibitor, RU486. We found that dexamethasone induced pancreatic β-cell apoptosis in association with the upregulation of TNSF10 (TRAIL) mRNA and protein expression. Moreover, dexamethasone upregulated the TRAIL death receptor (DR5) protein but suppressed the decoy receptor (DcR1) protein. Similar findings were observed in mouse isolated islets: dexamethasone increased TRAIL and DR5 compared to that of control mice. Furthermore, dexamethasone stimulated pro-apoptotic signaling including superoxide production, caspase-8, -9, and -3 activities, NF-κB, and Bax but repressed the anti-apoptotic protein, Bcl-2. All these effects were inhibited by the GR-inhibitor, RU486. Furthermore, knock-down DR5 decreased dexamethasone-induced caspase 3 activity. Caspase-8 and caspase-9 inhibitors protected pancreatic β-cells from dexamethasone-induced apoptosis. Taken together, dexamethasone induced pancreatic β-cell apoptosis by binding to the GR and inducing DR5 and TRAIL pathway.

Engineering Exosomes Endowed with Targeted Delivery of Triptolide for Malignant Melanoma Therapy.

Malignant melanoma is considered the most aggressive skin carcinoma with invasive growth patterns. Triptolide (TPL) possesses various biological and pharmacological activities involved in cancer treatment. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce cancer cell apoptosis by binding to DR5 highly expressed on cancer cells. Exosomes are natural nanomaterials with low immunogenicity, nontoxicity, and excellent biocompatibility and have been extensively used as emerging delivery vectors for diverse therapeutic cargos. Herein, a delivery system based on TRAIL-engineered exosomes (TRAIL-Exo) for loading TPL for targeted therapy against malignant melanoma is proposed and systematically investigated. Our results showed that TRAIL-Exo/TPL could improve tumor targetability, enhance cellular uptake, inhibit proliferation, invasion, and migration, and induce apoptosis of A375 cells through activating the extrinsic TRAIL pathway and the intrinsic mitochondrial pathway in vitro. Moreover, intravenous injection of TRAIL-Exo/TPL significantly suppressed tumor progression and reduced the toxicity of TPL in the melanoma nude mouse model. Together, our research presents a novel strategy for high-efficiency exosome-based drug-delivery nanocarriers and provides an alternative dimension for developing a promising approach with synergistic therapeutic efficacy and targeting capacity for melanoma treatment.

Abstract 1060: Combinatorial therapy of imipridones and histone deacetylase inhibitors in Ewing sarcoma cell lines demonstrates synergistic cell death

Abstract Novel therapies are much needed in treating pediatric sarcomas, such as Ewing sarcoma. In the setting of metastatic Ewing sarcoma, survival expectancy ranges around 10%. A novel class of small molecules, imipridones, target G protein-coupled receptors and mitochondrial protease ClpP. Imipridones inactivate cell proliferation kinases Akt/ERK and induce cell death through the pro-apoptotic tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its receptor DR5. In pre-clinical and clinical trials, imipridone ONC201 shows increased activity against tumors with mutations in histones, specifically histone H3 at the location of lysine 27 (H3K27). Changes in histone acetylation and the epigenetic effects of imipridones remain under investigation. Most commonly caused by a fusion of the EWS-FLI1 genes, Ewing sarcoma exhibits epigenetic modifications with the EWS-FLI1 protein acting as a transcription factor that causes covalent modifications of histone H3, including acetylation and activation of H3K27. Ewing sarcomas have also shown in vitro response to ERK pathway inhibition, leading to apoptosis and inhibition of metastasis formation. We hypothesized that Ewing sarcoma cell lines, with increased H3K27 acetylation due to EWS-FLI1 acting as an activating transcription factor, would respond to the combination of imipridones with histone deacetylase inhibitors. We performed combinatorial drug treatment on Ewing sarcoma cell lines SK-N-MC and RD-ES with 3 imipridones (ONC201, ONC206, and ONC212) and 3 HDAC inhibitors (vorinostat, entinostat, and panobinostat). Cell viability was measured after drug treatment in vitro. We investigated markers of cell death in established pediatric sarcoma cell lines via protein analysis and flow cytometry analysis. Using protein quantification studies and downstream target analysis on combination drug-treated cells, we investigated the mechanisms of how these two targeted therapies interact synergistically to cause cell death. We show that imipridones inactivate cellular proliferation through the Akt/ERK pathway and induce cell death through the TRAIL pathway, with ONC212 exhibiting the highest cell killing potency. Protein quantification by Western blotting revealed treatment with imipridone ONC201 affected the mitochondrial Clp protease complex by decreasing the chaperone subunit ClpX. Cell viability studies and analysis with Compusyn demonstrate potent synergistic effects causing tumor cell death when imipridones are combined with HDAC inhibitors. Our work presents a novel therapeutic combination for the treatment of Ewing sarcoma. Citation Format: Wen-i Chang, Lanlan Zhou, Attila Seyhan, Varun V. Prabhu, Wafik S. El-Deiry. Combinatorial therapy of imipridones and histone deacetylase inhibitors in Ewing sarcoma cell lines demonstrates synergistic cell death [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1060.

Abstract 3902: Novel therapeutic targeting of epigenetic aberrations in pediatric sarcomas through combination of ONC201 and HDAC inhibitors

Abstract Patients diagnosed with pediatric sarcomas have poor outcomes with current standard therapy in the setting of relapse, progressive disease, or upfront metastasis. Imipridones, a class of novel small molecules, specifically ONC201, have shown pre-clinical and clinical efficacy in adult malignancies and in brain tumors with aberrant methylation of histone H3 on lysine 27 (associated with H3K27M mutation). ONC201 is an antagonist of dopamine receptor D2 (DRD2), which is a G protein-coupled receptor that is overexpressed in several malignancies. ONC201 inactivates cell proliferation kinases Akt/ERK and induces cell death through the pro-apoptotic tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its receptor DR5. Prior in vitro studies of pediatric sarcomas have produced promising data with ERK pathway inhibition, leading to apoptosis and inhibition of metastasis formation. Some pediatric sarcomas, such as malignant peripheral nerve sheath tumors and fusion-positive sarcomas, have been noted to have aberrant activation or modifications of H3K27. H3K27 can be methylated or acetylated and both modifications are abrogated in H3K27M mutated alleles. Changes in histone acetylation and the epigenetic effects of imipridones remain under investigation. We hypothesized that sarcomas with aberrant H3K27 modifications may respond to the novel small molecule similarly to H3K27-mutated brain tumors, and that the combination of ONC201 with histone deacetylase inhibitors (HDACi) could lead to a synergistic effect on cell death mechanisms, potentially through effects of histone acetylation. We performed drug treatment with ONC201 on established pediatric sarcoma cell lines and applied combinatory drug treatment with HDACi, including vorinostat (SAHA). Cell viability was measured after drug treatment in vitro. We investigated markers of cell death in established pediatric sarcoma cell lines via protein analysis and flow cytometry analysis. Using protein quantification studies and downstream target analysis on combination drug-treated cells, we investigated the mechanisms of how these two targeted therapies interact synergistically to cause cell death. We show that ONC201 inactivates cellular proliferation in pediatric sarcomas through the Akt/ERK pathway and induces cell death through the TRAIL pathway. We demonstrated that treatment of cells with ONC201 modified the mitochondrial Clp protease complex, by activating the ClpP protease and by decreasing the chaperone subunit ClpX. Our studies demonstrate that ONC201 induces cell death in pediatric sarcomas, and that ONC201 has potent synergistic effects causing tumor cell death when combined with HDACi. Further studies are underway in elucidating the combinatory epigenetic effects of HDACi and ONC201 in H3K27-aberrant sarcomas, leading to synergistic cell death mechanisms. Our studies present a novel therapeutic combination for pediatric sarcomas that have relapsed or are refractory to standard chemotherapy. Citation Format: Wen-I Chang, Lanlan Zhou, Attila A. Seyhan, Yiqun Zhang, Wafik S. El-Deiry. Novel therapeutic targeting of epigenetic aberrations in pediatric sarcomas through combination of ONC201 and HDAC inhibitors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3902.

Ischemic Preconditioning Upregulates Decoy Receptors to Protect SH-SY5Y Cells from OGD Induced Cellular Damage by Inhibiting TRAIL Pathway and Agitating PI3K/Akt Pathway.

As ischemic preconditioning (IPC) represents a potential therapy against cerebral ischemia, the purpose of the present study is to explore the molecular mechanisms of ischemic preconditioning induced cerebral protective effect. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor superfamily, which induces apoptosis through binding to its death receptors (DR4 and DR5). When TRAIL binds to decoy receptors (DcR1 and DcR2), as DcRs lack intact cytoplasmic death domain, TRAIL fails to induce neuronal apoptosis. In the present study, we demonstrated that ischemic preconditioning upregulated DcR1 and DcR2, which subsequently inhibited oxygen glucose deprivation-induced cellular apoptosis. Then, we investigated the protective molecular mechanism of DcRs after ischemic preconditioning treatment. Results showed that DcR1 could competitively bind to TRAIL and partially inhibit TRAIL-induced cellular apoptosis. On the other hand, DcR2 could disturb DRs-associated death-inducing signaling complex formation (DISC), which further inhibited capase-8 activation. Besides, we also found that ischemic preconditioning activated IPC-induced Akt phosphorylation via regulating DcR2 level. Thus, ischemic preconditioning upregulated decoy receptors, which protected cells from oxygen glucose deprivation-induced cellular damage by inhibiting TRAIL-induced apoptosis and agitating PI3K/Akt pathway. Our data complemented the knowledge of neuroprotective mechanism of ischemic preconditioning and provided new evidence for supporting its clinical application.

Abstract 3469: CYP1B1 induces cancer progression through regulation of TRAIL pathway and uPA-uPAR system

Abstract Human CYP1B1 is known as a major metabolizer for estrogen and shows tumor-specific hyper-expression. To explore the role of CYP1B1 on progression of human cancer cells, we studied the effects of CYP1B1 in MCF-7, MDA-MB-231, and HeLa cells. CYP1B1 significantly induced invasion of cancer cells while strongly inhibited cancer cell apoptosis. Suppression of CYP1B1 by si/shRNA or treatment with TMS, a specific inhibitor for CYP1B1, markedly increased the protein expression level along with the level of release from cells of TNF-related apoptosis inducing ligand (TRAIL), a death ligand for cancer cells, whereas significantly decreased the expression of urokinase-type plasminogen activator receptor (uPAR) as well as uPA. We also found that CYP1B1 showed to inhibit the expression of key factors in TRAIL-induced apoptotic pathway and promote the inducers in uPA-uPAR metastasis system including integrin β1 and α5. Interestingly, uPAR overexpression only caused a significant increase of integrin β1 and α5 in protein levels, indicating protein degradation may play an important role in regulating integrin protein level. Surprisingly, CYP1B1 down-regulated p53 expression through MDM2 activation and nutlin-3a, an inhibitor for MDM2, blocked the promoting effects of CYP1B1 inducer, DMBA, on uPAR, which explains that CYP1B1 induced uPAR expression through regulation of MDM2-p53 system. Furthermore, we found that CYP1B1 suppresses TRAIL-related apoptosis through not only inhibition of TRAIL expression but also induction of DNA methylation on the promoter region of DR4, a receptor for TRAIL. Taken together, our data suggest that CYP1B1 promotes cancer cell metastasis via activating uPA-uPAR pathway which is one of the targets of p53 signaling and suppresses cancer cell apoptosis through inhibition of TRAIL-induced apoptosis by suppression of TRAIL release as well as post-translational regulation on DR4. Citation Format: Yeo-Jung Kwon, Young-Jin Chun. CYP1B1 induces cancer progression through regulation of TRAIL pathway and uPA-uPAR system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3469.

Targeting of dermal myofibroblasts through death receptor 5 arrests fibrosis in mouse models of scleroderma

Scleroderma is an autoimmune rheumatic disorder accompanied by severe fibrosis in skin and other internal organs. During scleroderma progression, resident fibroblasts undergo activation and convert to α-smooth muscle actin (α-SMA) expressing myofibroblasts (MFBs) with increased capacity to synthesize collagens and fibrogenic components. Accordingly, MFBs are a major therapeutic target for fibrosis in scleroderma and treatment with blocking MFBs could produce anti-fibrotic effects. TLY012 is an engineered human TNF-related apoptosis-inducing ligand (TRAIL) which induces selective apoptosis in transformed cells expressing its cognate death receptors (DRs). Here we report that TLY012 selectively blocks activation of dermal fibroblasts and induces DR-mediated apoptosis in α-SMA+ MFBs through upregulated DR5 during its activation. In vivo, TLY012 reverses established skin fibrosis to near-normal skin architecture in mouse models of scleroderma. Thus, the TRAIL pathway plays a critical role in tissue remodeling and targeting upregulated DR5 in α-SMA+ MFBs is a viable therapy for fibrosis in scleroderma.

Abstract LB-082: ONC201 sensitizes resistant breast cancer cells to TRAIL through death receptor 5 upregulation

Abstract ONC201 is a potent inducer of cancer cell death through the tumor necrosis factor related apoptosis inducing ligand (TRAIL) pathway. ONC201 and its structural analogs comprise a novel class known as the imipridones. The compound is being tested clinically against a range of solid tumors and hematological malignancies. We found that both triple negative and non-triple negative breast cancer cells are sensitive to ONC201. This was initially surprising, as the majority of non-triple negative breast cancer cells are resistant to TRAIL. In TRAIL-sensitive cells, ONC201 induced cell death in a TRAIL-dependent manner. In TRAIL-resistant cells, the effects of ONC201 are not pro-apoptotic but are rather anti-proliferative. Here we further investigate the effects of ONC201 in TRAIL-resistant breast cancers from multiple molecular subtypes. ONC201 has been previously shown to induce transcriptional upregulation of TRAIL receptor death receptor 5 (DR5). A known mechanism of TRAIL resistance in breast cancer is low cell surface DR5 expression. We hypothesized that pre-treatment with ONC201 would upregulate DR5 and lead to TRAIL sensitization in resistant cells. Our results confirm our hypothesis and show that treatment with ONC201 transcriptionally upregulates DR5 and increases its expression at the cell surface. In addition, pre-treatment with ONC201 sensitizes TRAIL-resistant breast cancer cells to the pro-apoptotic effects of TRAIL. Caspase-8 and PARP are cleaved when cells are treated with the combination of ONC201 and TRAIL, but not when treated with either compound alone. Annexin-V PI staining and quantitation of subG1 DNA content via flow cytometry further confirmed these results. Knockdown of DR5 abrogated TRAIL sensitization by ONC201. Natural killer (NK) cells are known to use TRAIL to kill targets like tumor cells. We are exploring the hypothesis that pre-treatment of tumor cells with ONC201 would increase their killing by NK cells. We are currently investigating the importance of the TRAIL pathway and DR5 upregulation by imipridone compounds in this sensitization to NK cell induced apoptosis. In summary, these results describe a novel mechanism by which ONC201 sensitizes breast cancer cells to the effects of apoptosis inducing ligand TRAIL. They also provide preclinical rationale for the testing of the compound against breast cancers in the clinic. Citation Format: Marie D. Ralff, Jessica Wagner, Wafik S. El-Deiry. ONC201 sensitizes resistant breast cancer cells to TRAIL through death receptor 5 upregulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-082.

Tumor Cell-selective Synergism of TRAIL- and ATRA-induced Cytotoxicity in Breast Cancer Cells.

One of the major problems in breast cancer treatment is pharmacoresistance. Therefore, exploration of treatment alternatives is of clinical relevance. The present work focused on tumor cell-inhibiting effects of a combination of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and all trans retinoic acid (ATRA) in breast cancer cells. Breast cancer cell lines (BT-20, BT-474, MDA-MB-231, MDA-MB-436, MDA-MB-453, MCF-7, SKBR3, T47D, ZR-75-1) and the mammary epithelial cell line MCF-10A were treated with TRAIL and ATRA alone and in combination. Cell viability was assessed via 3-(4,5)-dimethylthiahiazo(-z-yl)-3,5-di-phenytetrazoliumromide (MTT) assay, the potential of cell colony formation via clonogenic assay, cell death induction via cell-cycle analysis by fluorescence-activated cell sorting (FACS), terminal deoxynucleotidyltransferase-mediated UTP nick end labeling (TUNEL) assay and Cell death detection ELISAPLUS, expression of apoptosis and TRAIL pathway proteins via western blot and cell surface expression of TRAIL receptor 1 (DR4) via FACS analysis. TRAIL and ATRA evoked synergistic inhibition of breast cancer cell viability based on cytostatic and cytotoxic mechanisms. This correlated with augmented fragmentation of nuclear DNA, up-regulation of TRAIL receptor, down-regulation of cyclin D1 and enhancement of caspase activity. MCF-10A cells were merely slightly susceptible to TRAIL and ATRA. The cytostatic and cytotoxic effects of the combination of TRAIL and ATRA are tumor cell-selective.

Comprehensive expression analysis of TNF-related apoptosis-inducing ligand and its receptors in colorectal cancer: Correlation with MAPK alterations and clinicopathological associations

TNF-related, apoptosis-inducing ligand (TRAIL) apoptotic pathway constitutes a promising therapeutic target due to high selectivity and low toxicity of TRAIL targeting agents when administered in combination therapies. 106 colorectal cancers were examined for: relative mRNA expression of TRAIL pathway genes, decoy receptors TRAIL-R3 and TRAIL-R4 promoter methylation and the presence of KRAS, NRAS, BRAF mutations. Elevated mRNA levels were observed in 26%, 15%, 13%, 12% and 10% of the cases for TRAIL-R4, TRAIL-R3, TRAIL-R2, TRAIL-R1 and TRAIL genes respectively. Reduced mRNA levels were detected in 77%, 65%, 64%, 60% and 37% of the cases for TRAIL, TRAIL-R2, TRAIL-R3, TRAIL-R1 and TRAIL-R4 genes respectively. TRAIL-R3 and TRAIL-R4 promoter methylation was detected in 55% and 16% of the analysed samples respectively. TRAIL-R1, TRAIL-R2 elevated relative mRNA levels inversely correlated with tumor stage (p = .036, p = .048). Strong linear correlations of TRAIL receptors’ mRNA levels were found: TRAIL-R1/TRAIL-R2 (R = 0.653, p < .001), TRAIL-R2/TRAIL-R3 (R = 0.573, p < .001). Finally, relative expression of TRAIL was correlated with KRAS, BRAF and NRAS mutation status, defining an inverse correlation between increased TRAIL expression and the absence of mutations in Mitogen-activated protein kinase (MAPK) pathway.In conclusion, simultaneous analysis of TRAIL pathway membrane components, pointed towards a significant deregulation of mRNA expression in colorectal tumours. Death receptor overexpression was an indicator of a less aggressive phenotype. The multiple expression patterns of TRAIL pathway components in colorectal tumours underscore the importance of patient selection in order to achieve maximum efficiency with TRAIL targeted therapy.

Developing TRAIL/TRAIL death receptor-based cancer therapies.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily that can initiate the apoptosis pathway by binding to its associated death receptors DR4 and DR5. The activation of the TRAIL pathway in inducing tumor-selective apoptosis leads to the development of TRAIL-based cancer therapies, which include recombinant forms of TRAIL, TRAIL receptor agonists, and other therapeutic agents. Importantly, TRAIL, DR4, and DR5 can all be induced by synthetic and natural agents that activate the TRAIL apoptosis pathway in cancer cells. Thus, understanding the regulation of the TRAIL apoptosis pathway can aid in the development of TRAIL-based therapies for the treatment of human cancer.

Cell death and restoration of TRAIL-sensitivity by ciglitazone in resistant cervical cancer cells.

Known activators of the Peroxisome Proliferator-Activated Receptor γ (PPARγ), thiazolidinediones (TZD) induce apoptosis in a variety of cancer cells through dependent and/or independent mechanisms of the receptor. We tested a panel of TZD (Rosiglitazone, Pioglitazone, Ciglitazone) to shed light on their potential therapeutic effects on three cervical cancer cell lines (HeLa, Ca Ski, C-33 A). In these cells, only ciglitazone triggered apoptosis through PPARγ-independent mechanisms and in particular via both extrinsic and intrinsic pathways in Ca Ski cells containing Human PapillomaVirus (HPV) type 16. It also inhibits cervical cancer xenograft development in nude mice. Ciglitazone kills cervical cancer cells by activating death receptor signalling pathway, caspase cascade and BH3 interacting-domain death agonist (Bid) cleavage through the up-regulation of Death Receptor 4 (DR4)/DR5 and soluble and membrane-bound TNF related apoptosis inducing ligand (TRAIL). Importantly, the drug let TRAIL-resistant Ca Ski cells to respond to TRAIL through the downregulation of cellular FLICE-Like Inhibitory Protein (c-FLIP) level. For the first time, we revealed that ciglitazone is able to decrease E6 viral oncoprotein expression known to block TRAIL pathway and this was associated with cell death. Our results highlight the capacity of ciglitazone to restore TRAIL sensitivity and to prevent E6 blocking action to induce apoptosis in cervical cancer cells.

Role of TRAIL pathway and NKG2D pathway in double negative T cell cell anti-tumor

Double negative T cell is a rare type of cells that regulates immune responses in a way that is unique. In the process of adoptive immunotherapy, it gradually becomes a hot spot, because of its obvious anti-tumor effect. However, the mechanism by which DNT cell kills tumor cell is not clear. Tumor necrosis factor-related apoptosis-inducing ligand(TRAIL) and natural-killer group 2, member D (NKG2D) pathway is a more important part of its killing mechanism, and NKG2D receptor can also regulate the production of soluble TRAIL, making the two channels to establish a certain link. In this paper, the effect of Double negative T cell and the mechanism of TRAIL and NKG2D pathway in DNT cell′s anticancer were described. Key words: Immunity; Pancreatic neoplasms; DNT cell; TRAIL; NKG2D