Expression Of Death Receptor Research Articles

Expression of Death Receptor 3 (DR3) on Circulating CD4 Positive Lymphocytes in Patients with Alopecia Areata

Alopecia areata (AA) is an autoimmune disorder characterized by transient hair loss and preservation of the hair follicle that affect both sexes.There is scarcity in the published data that discuss the role of DR3 in pathogenesis and prognosis of AA. Therefore, our study was conducted to study this role by assessment of DR3 expression on circulating CD4 positive lymphocytes in AA patients. This study was a case control study that included 50 patients with AA in addition to 50 apparently healthy individuals of matched age and sex as a control group. Assessment of DR3 expression on circulating CD4 positive lymphocytes on both groups was done by flow cytometric analysis. Results of the present study demonstrated a significant difference in DR3 expression level between AA patients and control group. DR3 expression level was considered as risk predictor of AA occurrence. In addition, it was considered as risk predictor of active and severe (higher SALT score) cases.

RNA-Seq identifies condition-specific biological signatures of ischemia-reperfusion injury in the human kidney

BackgroundAcute kidney injury (AKI) is defined as a sudden event of kidney failure or kidney damage within a short period. Ischemia-reperfusion injury (IRI) is a critical factor associated with severe AKI and end-stage kidney disease (ESKD). However, the biological mechanisms underlying ischemia and reperfusion are incompletely understood, owing to the complexity of these pathophysiological processes. We aimed to investigate the key biological pathways individually affected by ischemia and reperfusion at the transcriptome level.ResultsWe analyzed the steady-state gene expression pattern of human kidney tissues from normal (pre-ischemia), ischemia, and reperfusion conditions using RNA-sequencing. Conventional differential expression and self-organizing map (SOM) clustering analyses followed by pathway analysis were performed. Differential expression analysis revealed the metabolic pathways dysregulated in ischemia. Cellular assembly, development and migration, and immune response-related pathways were dysregulated in reperfusion. SOM clustering analysis highlighted the ischemia-mediated significant dysregulation in metabolism, apoptosis, and fibrosis-related pathways, while cell growth, migration, and immune response-related pathways were highly dysregulated by reperfusion after ischemia. The expression of pro-apoptotic genes and death receptors was downregulated during ischemia, indicating the existence of a protective mechanism against ischemic injury. Reperfusion induced alterations in the expression of the genes associated with immune response such as inflammasome and antigen representing genes. Further, the genes related to cell growth and migration, such as AKT, KRAS, and those related to Rho signaling, were downregulated, suggestive of injury responses during reperfusion. Semaphorin 4D and plexin B1 levels were also downregulated.ConclusionsWe show that specific biological pathways were distinctively involved in ischemia and reperfusion during IRI, indicating that condition-specific therapeutic strategies may be imperative to prevent severe kidney damage after IRI in the clinical setting.

Abstract 6325: CXCR4 intracellular protein regulates chemotherapy resistance by modulating the expression of death receptor 5

Abstract Chemotherapy resistance is one of the pivotal reasons for cancer-associated huge mortality and morbidity. Cancer cells become therapy resistant by smartly evading the execution of apoptosis. Death Receptors (DR) are critical pro-apoptotic factors that regulate cell death, and paucity of death receptors in cancer cells promotes therapy resistance. High expression of CXCR4 is strongly correlated with poor prognosis and adverse clinical outcomes. Inhibitors of the CXCL12-CXCR4 axis, such as FDA approved drug plerixafor (AMD3100), and Nox-A12 have shown limited clinical success in cancer treatment. Alternately, CXCR7, another CXCL12 binding receptor, could be the reason for the limited success of the CXCR4 blockade in clinics. However, recent preclinical data for blocking both the chemokine receptors failed to explain the pro-tumorigenic functions of these axes. Therefore, CXCR4-CXCL12 signaling may not be the exclusive contributor to its pro-tumorigenic functions. In our continuous effort to understand the chemokine receptor signaling inhibition as cancer therapy, here we unexpectedly discovered that instead of CXCR4-CXCL12 signaling, CXCR4 intracellular protein augments therapy resistance and pro-tumorigenic functions. By utilizing stable gain and loss of function approaches, we observed that CXCR4 selectively resists and sensitizes cancer cells against paclitaxel therapy. Our unbiased apoptosis array followed by immunoblot, FACS, real-time PCR, and ChIP analysis clearly demonstrate that CXCR4 promotes downregulation of pro-apoptotic protein DR5 via modulating differential recruitment of transcription factors p53 and YY1 to the promoter of DR5 gene. Inhibiting CXCR4 mediated signals failed to block the above phenotype. Irrespective of CXCR4 surface expression, three different colon cancer xenograft models evidently exhibited loss of CXCR4 protein results in compromised colon tumor growth in vivo. Finally, performing TCGA data mining, real-time PCR, immunofluorescence microscopy of human cancer patient samples and cell lines, we observed that expression of CXCR4 and DR5 are inversely correlated in human cancer. Together, we showed for the first time that targeting intracellular CXCR4 protein may be critical to dampen the pro-tumorigenic functions of CXCR4. Citation Format: Mushtaq Ahmad Nengroo, Shrankhla Maheshwari, Akhilesh Singh, Anup Kumar Singh, Priyank Chaturvedi, Ayushi Verma, Rakesh Kumar Arya, Krishan Kumar Saini, Annapurna Gupta, Anjali Mishra, Dipak Datta. CXCR4 intracellular protein regulates chemotherapy resistance by modulating the expression of death receptor 5 [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 6325.

Abstract LB-069: TRAILing chemoresistance: Oxaliplatin resistance sensitizes colorectal cancer to TRAIL via death receptor localization

Abstract Colorectal cancer (CRC) remains the second leading cause of cancer related death in the United States. Clinical studies show combination chemotherapy cocktails increase Stage IV patient progression free survival when containing 5-fluorouracil, leucovorin and oxaliplatin (FOLFOX). Despite an initial response rate of 40-50%, patients undergoing FOLFOX have a low median overall survival of 18-months. Treatment induced chemoresistance is in part responsible for this high morbidity, as subpopulations of surviving cells develop resistance mechanisms to induce a more aggressive, metastatic phenotype. Consequently, there exists an urgent need to develop new therapies for metastatic cancers that have become chemoresistant. We hypothesized that Tumor Necrosis factor - α Related Apoptosis Inducing Ligand (TRAIL) based therapeutics would be efficacious in treating oxaliplatin resistant CRC, providing an adjuvant for patients who have exhausted conventional treatment modalities. Four different CRC cell lines were chosen for this study: SW620, SW480, HCT116 and HT29 cells as they all have varying sensitivities to TRAIL. Briefly, oxaliplatin resistant (OxR) derivatives of these cell lines were developed by treating with oxaliplatin and subjecting surviving subpopulations to many rounds of increasing concentrations of chemotherapy. Resistant cells show increased expression of mesenchymal markers along with increased invasiveness. Metastatic CRC patient blood samples were obtained from Guthrie Clinic. Interestingly, SW620 OxR and HCT116 OxR cells show increased sensitization to soluble TRAIL compared to their parental counterparts. Flow cytometry and confocal microscopy demonstrate these sensitized cell lines have increased expression of death receptor 4 (Dr4). Previous studies have demonstrated that combination treatment with oxaliplatin and TRAIL sensitize cancer cells via localization of death receptors into lipid rafts. In our study, we observe a similar phenomenon where oxaliplatin resistant cells have a higher degree of lipid raft-Dr4 colocalization. Induction of death receptor-lipid raft complexes using resveratrol enhances parental SW620 cell sensitivity to TRAIL by 70%, whereas inhibition of lipid rafts via cholesterol sequestration using nystatin decreases sensitization of SW620 OxR cells by 30%. Circulating tumor cells (CTCs) from metastatic CRC patients who have undergone FOLOFX or oxaliplatin based chemotherapy exhibited colocalization of Dr4 and Dr5 into lipid rafts. Additionally, treating whole blood samples from patients with TRAIL-conjugated nanoparticles decreased the number of viable CTCs in circulation 4-fold compared to oxaliplatin monotherapy. These results demonstrate the utility of TRAIL based therapeutics to treat chemoresistant and metastatic CRC. Additionally, this mechanism of apoptosis signal propagation via lipid raft-death receptor complexes can be explored further to probe possible drug targets to augment receptor localization. Citation Format: Joshua Dale Greenlee, Nerymar Ortiz-Otero, Tejas Subramanian, Kevin Liu, Michael King. TRAILing chemoresistance: Oxaliplatin resistance sensitizes colorectal cancer to TRAIL via death receptor localization [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 LB-069.

Abstract 5403: Targeting death-receptors in therapy resistant progressive neuroblastoma: A preliminary insight

Abstract Neuroblastoma is the most common cancer in infants and accounts for 9.1% of childhood cancer-related deaths. Despite the current standard of care (SOC), drug-resistant neuroblastoma significantly compromises patient survival. Hence it is critical to identify new and less toxic therapeutic approaches for better patient outcomes. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), which mediates its effect through the activation of the death receptor (DR) 4 and 5 are found on many cell types and are the main pathway for apoptosis. These can death receptors can kill most tumor cell types expressing TRAIL-receptor 1. Mining RNA-Seq data across multiple cohorts of neuroblastoma patients indicated that high levels of DR4 and DR5 significantly associated with poor clinical outcomes (OS, EFS, RFS). Further, examining the surface expression of DR4 and DR5 by immunohistochemistry using anti-human rabbit monoclonal antibodies on custom-archived TMAs for 100 NB patients revealed profound correlation with poor OS and RFS. Immunoblot analysis for DR4 and DR5 level in a panel of stage 4 patient-derived cell-lines during diagnosis and from progressive disease after therapy displayed high-levels of death receptor expression in progressive disease. Preliminary co-culture investigations with genetically engineered mesenchymal stem cells (MSCs) expressing tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) mimicking targeted delivery showed heightened differentiation and death (limited dilution tumorosphere assay) of therapy resistant cells. Further these studies exhibited inhibition of tumor cell migration and invasion. The results demonstrate the benefit of targeted TRAIL delivery in in the treatment of therapy resistant neuroblastoma and further imply that the genetically engineered MSCs could serve as a clinically valuable tool for improved therapeutic strategy in this setting. Citation Format: Dinesh Babu Somasundaram, Andrew Maher, Sheeja Aravindan, Terence S. Herman, Natarajan Aravindan. Targeting death-receptors in therapy resistant progressive neuroblastoma: A preliminary insight [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 5403.

Luteolin enhances TRAIL sensitivity in non-small cell lung cancer cells through increasing DR5 expression and Drp1-mediated mitochondrial fission

Cancer cells exhibit extreme sensitivity to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) over normal cells, highlighting TRAIL's potential as a novel and effective cancer drug. However, the therapeutic effect of TRAIL is limited due to drug resistance. In the present study, we sought to investigate the potential effects of luteolin as a TRAIL sensitizer in non-small cell lung cancer (NSCLC) cells. A549 and H1975 cells had low sensitivity or were resistant to TRAIL. Luteolin alone or in combination with TRAIL decreased cell viability and increased apoptosis. Furthermore, luteolin alone or in combination with TRAIL enhanced death receptor 5 (DR5) expression and dynamin-related protein 1 (Drp1)-dependent mitochondrial fission. However, the synergistic effect of luteolin on cell viability and apoptosis was reversed by DR5 and Drp1 inhibition, suggesting that DR5 upregulation and mitochondrial dynamics may be essential for luteolin as a sensitizer of TRAIL-based therapy in NSCLC. Moreover, luteolin treatment alone or in combination with TRAIL increased the phosphorylation of c-Jun N-terminal kinase (JNK), while SP600125 (the JNK inhibitor) significantly abolished the synergistic effect on DR5 expression and Drp1 translocation, indicating that JNK signaling activation was greatly associated with the synergistic effect exerted by luteolin in NSCLC cells. Therefore, TRAIL combined with luteolin could be as an effective chemotherapeutic strategy for NSCLC.

HIF-1α Mediates TRAIL-Induced Neuronal Apoptosis via Regulating DcR1 Expression Following Traumatic Brain Injury.

Background: Neuronal apoptosis involved in secondary injury following traumatic brain injury (TBI) significantly contributes to the poor outcomes of patients with TBI. The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can selectively induce apoptosis of tumor cells. Hypoxia factor (HIF) 1α is a controversial factor that mediates the neuronal apoptotic pathway. Herein, we hypothesize that HIF-1α may mediate the TRAIL-induced neuronal apoptosis after TBI.Methods: We used Western blots and immunofluorescence to study the expression and cell localization of TRAIL and death receptor 5 (DR5) after TBI in rats. Soluble DR5 (sDR5) administration was used to block the TRAIL-induced neuronal death and neural deficits. HIF-1α inhibitor 2ME and agonist DMOG were used to study the role of HIF-1α in TRAIL-induced neuronal death. Meanwhile, HIF-1α siRNA was used to investigate the role of HIF-1α in TRAIL-induced neuronal death in vitro.Results: The expressions of microglia-located TRAIL and neuron-located DR5 were significantly upregulated after TBI. sDR5 significantly attenuated TRAIL-induced neuronal apoptosis and neurological deficits. 2ME decreased neuronal apoptosis, lesion area, and brain edema and improved neurological function via increased expression of TRAIL decoy receptor 1 (DcR1), which inhibited TRAIL-induced apoptosis after TBI. The administration of DMOG produced the opposite effect than did 2ME. Similarly, HIF-1α siRNA attenuated TRAIL-induced neuronal death via increased DcR1 expression in vitro.Conclusion: Our findings suggested that the TRAIL/DR5 signaling pathway plays an important role after neuronal apoptosis after TBI. HIF-1α mediates TRAIL-induced neuronal apoptosis by regulating DcR1 expression following TBI.

Imipridone enhances vascular relaxation via FOXO1 pathway.

Cardiovascular complications are a side effect of cancer therapy, potentially through reduced blood vessel function. ONC201 (TIC10) is currently used in phase 2 clinical trials to treat high-grade gliomas. TIC10 is a phosphatidylinositol 3-kinase (PI3K)/AKT/extracellular signal-regulated kinase (ERK) inhibitor that induces apoptosis via upregulation of TNF-related apoptosis-inducing ligand, which via stimulation of FOXO and death receptor could increase eNOS upregulation. This has the potential to improve vascular function through increased NO bioavailability. Our aim was to investigate the role of TIC10 on vascular function to determine if it would affect the risk of CVD. Excised abdominal aorta from White New Zealand male rabbits were cut into rings. Vessels were incubated with TIC10 and AS1842856 (FOXO1 inhibitor) followed by cumulative doses of acetylcholine (Ach) to assess vessel function. Vessels were then processed for immunohistochemistry. Incubation of blood vessels with TIC10 resulted in enhanced vasodilatory capacity. Combination treatment with the FOXO1 inhibitor and TIC10 resulted in reduced vascular function compared to control. Immunohistochemical analysis indicated a 3-fold increase in death receptor 5 (DR5) expression in the TIC10-treated blood vessels but the addition of the FOXO1 inhibitor downregulated DR5 expression. The expression of DR4 receptor was not significantly increased in the presence of TIC10; however, addition of the FOXO1 inhibitor downregulated expression. TIC10 has the capacity to improve the function of healthy vessels when stimulated with the vasodilator Ach. This highlights its therapeutic potential not only in cancer treatment without cardiovascular side effects, but also as a possible drug to treat established CVD.

Rationally designed redirection of natural killer cells anchoring a cytotoxic ligand for pancreatic cancer treatment

The emergence of T-cell engineering with chimeric antigen receptors (CARs) has led to attractive therapeutics; however, autologous CAR-T cells are associated with poor clinical outcomes in solid tumors because of low safety and efficacy. Therefore, the aim of our study was to develop a CAR therapy with enhanced cytotoxicity against solid cancer using allogeneic NK cells. In this study, we engineered “off-the-shelf” NK cells to redirect them towards pancreatic ductal adenocarcinoma (PDAC) by improving their target-specific cytotoxic potential. By integrated bioinformatic and clinicopathological analyses, folate receptor alpha (FRα) and death receptor 4 (DR4) were significantly highly expressed in patient-derived tumor cells. The combined expression of FRα and DR4/5 was associated with inferior clinical outcomes, therefore indicating their use as potential targets for biomolecular treatment. Thus, FRα and DR4 expression pattern can be a strong prognostic factor as promising therapeutic targets for the treatment of PDAC. For effective PDAC treatment, allogeneic CAR-NK cells were reprogrammed to carry an apoptosis-inducing ligand and to redirect them towards FRα and initiate DR4/5-mediated cancer-selective cell death in FRα- and DR4/5-positive tumors. As a result, the redirected cytotoxic ligand-loaded NK cells led to a significantly enhanced tumor-selective apoptosis. Accordingly, use of allogeneic CAR-NK cells that respond to FRα and DR4/5 double-positive cancers might improve clinical outcomes based on personal genome profiles. Thus, therapeutic modalities based on allogeneic NK cells can potentially be used to treat large numbers of patients with optimally selective cytotoxicity.

Inhibition of autophagy flux by sertraline attenuates TRAIL resistance in lung cancer via death receptor5 upregulation.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potential target for cancer therapy, owing to its ability to selectively kill cancer cells without causing significant toxicity to normal cells. However, due to the lack of death receptor expression, cancer cells can become highly resistant to TRAIL. Hence, it is vital to develop agents that restore TRAIL efficacy. Sertraline is an antidepressant drug with anticancer properties. To the best of our knowledge, this is the first study to demonstrate that sertraline inhibits autophagic flux and increases the expression of death receptor 5 (DR5) on TRAIL-resistant lung cancer cells. Inhibition of autophagy using autophagy inhibitors 3-methyladenine and chloroquine upregulated the expression of DR5 and enhanced TRAIL-induced apoptosis, as confirmed by the increase of pro-apoptotic proteins caspase-8 and caspase-3. Silencing DR5 expression using DR5 small interfering RNA prevented sertraline-induced TRAIL-mediated apoptosis, indicating the role of DR5 in TRAIL-mediated apoptosis. Overall, sertraline enhanced TRAIL-mediated apoptosis via the downregulation of AMP-activated protein kinase phosphorylation, resulting in the inhibition of autophagic flux, upregulation of DR5 expression, and activation of the apoptotic caspase cascade. These data suggested that sertraline could be used to sensitize human lung cancer cells to TRAIL, while also serving as a therapeutic option in cancer patients with depression.

Knockdown of Enhancer of Zeste Homolog 2 Affects mRNA Expression of Genes Involved in the Induction of Resistance to Apoptosis in MOLT-4 Cells.

The Enhancer of Zeste Homolog 2 (EZH2) is a subunit of the polycomb repressive complex 2 that silences the gene transcription via H3K27me3. Previous studies have shown that EZH2 has an important role in the induction of the resistance against the Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL)-Induced Apoptosis (TIA) in some leukemia cells. The aim of this study was to determine the effect of silencing EZH2 gene expression using RNA interference on the expression of death receptors 4 and 5 (DR4/5), Preferentially expressed Antigen in Melanoma (PRAME), and TRAIL human lymphoid leukemia MOLT-4 cells. Quantitative RT-PCR was used to detect the EZH2 expression and other candidate genes following the siRNA knockdown in MOLT-4 cells. The toxicity of the EZH2 siRNA was evaluated using Annexin V/PI assay following the transfection of the cells by 80 pM EZH2 siRNA at 48 hours. Based on the flow-cytometry results, the EZH2 siRNA had no toxic effects on MOLT-4 cells. Also, the EZH2 inhibition increased the expression of DR4/5 but reduced the PRAME gene expression at the mRNA levels. Moreover, the EZH2 silencing could not change the TRAIL mRNA in the transfected cells. Our results revealed that the down-regulation of EZH2 in MOLT-4 cells was able to affect the expression of important genes involved in the induction of resistance against TIA. Hence, we suggest that the silencing of EZH2 using RNA interference can be an effective and safe approach to help defeat the MOLT-4 cell resistance against TIA.

Basal Signalling Through Death Receptor 5 and Caspase 3 Activates p38 Kinase to Regulate Serum Response Factor (SRF)-Mediated MyoD Transcription.

We have previously reported that stable expression of a dominant negative Death Receptor 5 (dnDR5) in skeletal myoblasts results in decreased basal caspase activity and decreased mRNA and protein expression of the muscle regulatory transcription factor MyoD in growth medium (GM), resulting in inhibited differentation when myoblasts are then cultured in differentiation media (DM). Further, this decreased level of MyoD mRNA was not a consequence of altered message stability, but rather correlated with decreased acetylation of histones in the distal regulatory region (DRR) of the MyoD extended promoter known to control MyoD transcription. As serum response factor (SRF) is the transcription factor known to be responsible for basal MyoD expression in GM, we compared the level of SRF binding to the non-canonical serum response element (SRE) within the DRR in parental and dnDR5 expressing myoblasts. Herein, we report that stable expression of dnDR5 resulted in decreased levels of serum response factor (SRF) binding to the CArG box in the SRE of the DRR. Total SRF expression levels were not affected, but phosphorylation indicative of SRF activation was impaired. This decreased SRF phosphorylation correlated with decreased phosphorylation-induced activation of p38 kinase. Moreover, the aforementioned signaling events affected by expression of dnDR5 could be appropriately recapitulated using either a pharmacological inhibitor of caspase 3 or p38 kinase. Thus, our results have established a signaling pathway from DR5 through caspases to p38 kinase activation, to SRF activation and the basal expression of MyoD.

Regulation of pancreatic cancer TRAIL resistance by protein O-GlcNAcylation

AbstractTRAIL-activating therapy is promising in treating various cancers, including pancreatic cancer, a highly malignant neoplasm with poor prognosis. However, many pancreatic cancer cells are resistant to TRAIL-induced apoptosis despite their expression of intact death receptors (DRs). Protein O-GlcNAcylation is a versatile posttranslational modification that regulates various biological processes. Elevated protein O-GlcNAcylation has been recently linked to cancer cell growth and survival. In this study, we evaluated the role of protein O-GlcNAcylation in pancreatic cancer TRAIL resistance, and identified higher levels of O-GlcNAcylation in TRAIL-resistant pancreatic cancer cells. With gain- and loss-of-function of the O-GlcNAc-adding enzyme, O-GlcNActransferase (OGT), we determined that increasing O-GlcNAcylation rendered TRAIL-sensitive cells more resistant to TRA-8-induced apoptosis, while inhibiting O-GlcNAcylation promoted TRA-8-induced apoptosis in TRAIL-resistance cells. Furthermore, we demonstrated that OGT knockdown sensitized TRAIL-resistant cells to TRA-8 therapy in a mouse model in vivo. Mechanistic studies revealed direct O-GlcNAc modifications of DR5, which regulated TRA-8-induced DR5 oligomerization. We further defined that DR5 O-GlcNAcylation was independent of FADD, the adapter protein for the downstream death-inducing signaling. These studies have demonstrated an important role of protein O-GlcNAcylation in regulating TRAIL resistance of pancreatic cancer cells; and uncovered the contribution of O-GlcNAcylation to DR5 oligomerization and thus mediating DR-inducing signaling.

Antitumor Activity of TRAIL-Mu3 Protein in vitro and in vivo and the Mechanisms

TRAIL-Mu3 was obtained by mutating the N-terminus of human tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) gene to an eight continuous arginine sequence. The present study was designed to explore the antitumor effect of this soluble mutant protein and the underlying mechanisms. The inhibitory effect of TRAIL-Mu3 on the proliferation of lung cancer cell lines NCI-H460, A549, NCI-H1299 and calu-1 was tested by CCK8 assay. The apoptotic rates of A549 and NCI-H460 treated by TRAIL-Mu3 were detected by flow cytometer (FCM). The expressions of apoptosis related proteins death receptor (DR) 4, DR5, Caspase-3, Caspase-8 and X-linked inhibitor of apoptosis protein (XIAP) were detected by Western blot .Moreover, a subcutaneous xenograft tumor mouse model of NCI-H460 was established and treated with TRAIL-Mu3 daily or every other day or three times a week. The expressions of DR4, DR5, Caspase-3, Caspase-8 and XIAP were detected by immunohistochemical staining. The in vitro study demonstrated that as compared to the TRAIL, the TRAIL-Mu3 was more toxic and pro-apoptotic by up-regulation of the expression and activity of DR4, Caspase-3 and Caspase-8. Also, the animal study showed a similar antitumor effect between treatment with TRAIL-Mu3 every other day and three time a week, which was better than daily use. All treatments significantly suppressed the growth of xenograft tumor, increased the expression or activity of DR4 and Caspase-3, and down-regulated the expression of XIAP ( P<0.05). TRAIL-Mu3 could improve antitumor activity in vivo and in vitro through elevating DR4 expression, activating Caspase-3/-8, and inhibiting XIAP activation.

Chemotherapeutic Agents Sensitize Resistant Cancer Cells to the DR5-Specific Variant DR5-B more Efficiently than to TRAIL by Modulating the Surface Expression of Death and Decoy Receptors.

TRAIL is considered a promising antitumor agent because it causes apoptosis of transformed cells without affecting normal cells. However, many types of tumors are cytokine resistant, and combination therapy with various chemotherapeutic drugs is being developed to overcome the resistance. We have demonstrated that the combination of TRAIL with doxorubicin, bortezomib, and panobinostat dramatically reduced the viability of TRAIL-resistant A549 and HT-29 cells. Chemotherapy even more efficiently sensitized cells to the DR5-specific mutant variant of TRAIL DR5-B, which does not have an affinity for decoy receptors. Bortezomib and doxorubicin greatly enhanced the surface expression of the death receptors DR5 and DR4, while panobinostat increased expression of DR5 and suppressed expression of DR4 in both cell lines. All drugs increased surface expression of the decoy receptors DcR1 and DcR2. Unlike the combined treatment, if the cells were pretreated with chemotherapy for 24 h, the cytotoxic activity of TRAIL was less pronounced, while sequential treatment of cells enhanced the effectiveness of DR5-B. The same results were obtained with agonistic anti-DR5 antibodies. Thus, the effectiveness of TRAIL was rather limited due to changes in the ratio of death and decoy receptors and DR5-specific agonists may be preferred in combination antitumor therapy regimens.

Epigallocatechin-3-Gallate Induces Apoptosis as a TRAIL Sensitizer via Activation of Caspase 8 and Death Receptor 5 in Human Colon Cancer Cells

Though epigallocatechin-3-gallate (EGCG), a major compound of green tea, has anti-diabetes, anti-obesity, anti-inflammatory, and antitumor effects, the underlying antitumor molecular mechanism of EGCG was not fully understood so far. Here the sensitizing effect of EGCG to tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL) was examined in colorectal cancers. Cotreatment of EGCG and TRAIL synergistically enhanced cytotoxicity and sub G1 accumulation, increased the number of terminal deoxynucleotidyl transferase-dT-mediated dUTP nick end labelling (TUNEL)-positive cells in SW480 and HCT116 cells. Furthermore, this cotreatment promoted the cleavages of poly (adenosine diphosphate-ribose) polymerase (PARP) and induced caspase 8 activation compared to TRAIL or EGCG alone in SW480 and HCT116 cells. Of note, cotreatment of EGCG and TRAIL increased the expression of death receptor 5 (DR5) at protein and mRNA levels and also DR5 cell surface level in colon cancer cells. Conversely, depletion of DR5 reduced the apoptotic activity of cotreatment of EGCG and TRAIL to increase cytotoxicity, sub-G1 population and PARP cleavages in colon cancer cells. Overall, our findings provide evidence that EGCG can be a sensitizer of TRAIL via DR5 and caspase 8 mediated apoptosis in colorectal cancer cells.

Improved melanoma suppression with target-delivered TRAIL and Paclitaxel by a multifunctional nanocarrier

Malignant melanoma, a highly dangerous type of skin cancer, is usually resistant to pro-apoptosis agents such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) due to low death receptor expression levels. After verifying combination of chemotherapy drug paclitaxel (PTX) and TRAIL could significantly enhance their anti-melanoma effects, we developed a liposomal melanoma target-delivery system with tumor microenvironment responsiveness (TRAIL-[Lip-PTX]C18-TR) to co-deliver TRAIL and PTX. TRAIL is attached to negatively-charged liposome surface while PTX is encapsulated inside, with final surface modification of a stearyl chain (C18) fused pH-sensitive cell-penetrating peptide (TR). Here, C18-TR could specifically binds to melanoma-rich integrin receptors αvβ3 for melanoma targeting, help release TRAIL in low pH microenvironment by reversing the liposomal charge, and facilitate consequent liposome internalization. TRAIL-[Lip-PTX]C18-TR displayed significantly better in vitro half-maximal inhibitory concentration (IC50) than other formulations, and an in vivo tumor inhibition rate of 93.8%. Mechanistic study revealed that this synergistic effect is associated with the upregulation of death receptors DR4/5 by PTX. This co-delivery system significantly improved TRAIL-based therapy against melanoma, and provided a simple platform to co-deliver other drugs/agents for melanoma treatment.

CUDC-907 enhances TRAIL-induced apoptosis through upregulation of DR5 in breast cancer cells.

CUDC-907 is a novel dual-acting inhibitor of phosphoinositide 3-kinase (PI3K) and histone deacetylase (HDAC). In this study, we aimed to explore the anticancer effects of CUDC-907 on human breast cancer cells. Our results showed that CUDC-907 effectively inhibited breast cancer cell proliferation. Flow cytometry analysis revealed that CUDC-907 induced cell cycle arrest and apoptosis in breast cancer cells. The combined treatment of CUDC-907 and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) resulted in a marked increase in apoptosis and cleavage of caspase-8, -9 and poly (ADP-ribose) polymerase (PARP) in breast cancer cells. CUDC-907 enhanced expressions of death receptor 5 (DR5), reduced the levels of anti-apoptotic molecules XIAP, Bcl-2 and Bcl-xL. Knockdown of DR5 abrogated apoptosis induced by the combination of CUDC-907 and TRAIL in breast cancer cells. CUDC-907 increased the phosphorylation of JNK and p38 MAPK. JNK inhibitor pretreatment attenuated CUDC-907-induced upregulation of DR5. In summary, CUDC-907 shows potent cytotoxicity against breast cancer cells and facilitates TRAIL-mediated apoptosis through DR5 upregulation. The combination of CUDC-907 and TRAIL may be a promising therapeutic approach in the treatment of breast cancer.

Integrated drug profiling and CRISPR screening identify essential pathways for CAR T-cell cytotoxicity

AbstractChimeric antigen receptor (CAR) T-cell therapy has proven effective in relapsed and refractory B-cell malignancies, but resistance and relapses still occur. Better understanding of mechanisms influencing CAR T-cell cytotoxicity and the potential for modulation using small-molecule drugs could improve current immunotherapies. Here, we systematically investigated druggable mechanisms of CAR T-cell cytotoxicity using >500 small-molecule drugs and genome-scale CRISPR-Cas9 loss-of-function screens. We identified several tyrosine kinase inhibitors that inhibit CAR T-cell cytotoxicity by impairing T-cell signaling transcriptional activity. In contrast, the apoptotic modulator drugs SMAC mimetics sensitized B-cell acute lymphoblastic leukemia and diffuse large B-cell lymphoma cells to anti-CD19 CAR T cells. CRISPR screens identified death receptor signaling through FADD and TNFRSF10B (TRAIL-R2) as a key mediator of CAR T-cell cytotoxicity and elucidated the RIPK1-dependent mechanism of sensitization by SMAC mimetics. Death receptor expression varied across genetic subtypes of B-cell malignancies, suggesting a link between mechanisms of CAR T-cell cytotoxicity and cancer genetics. These results implicate death receptor signaling as an important mediator of cancer cell sensitivity to CAR T-cell cytotoxicity, with potential for pharmacological targeting to enhance cancer immunotherapy. The screening data provide a resource of immunomodulatory properties of cancer drugs and genetic mechanisms influencing CAR T-cell cytotoxicity.

Icariin sensitizes human colon cancer cells to TRAIL‑induced apoptosis via ERK‑mediated upregulation of death receptors.

Tumor necrosis factor‑associated apoptosis‑inducing ligand (TRAIL) is considered to be a potential therapeutic target for various types of cancer. However, colon cancer is difficult to treat due to its resistance to TRAIL. Therefore, various trials have been conducted to overcome TRAIL resistance in colon cancer. The present study aimed to determine whether icariin (ICA) may sensitize human colon cancer cells to TRAIL‑induced apoptosis invitro and invivo. In the investigation of the effect of ICA on TRAIL‑induced apoptosis, the LIVE/DEAD assay results demonstrated that TRAIL plus ICA synergistically induced apoptosis in 49% of HCT116colon cancer cells. These results were confirmed using long‑term colony formation assay. ICA potentiated TRAIL‑induced apoptosis by modulating the expression of apoptotic proteins and the induction of cell surface death receptors(DRs)4and5. Upregulation of DRs by ICA was also observed at the transcriptional level by RT‑PCR. The expression of DR by ICA was increased through the production of reactive oxygen species (ROS). The results also suggested that increased expression of DR by ICA may be due to the activation of ERK and induction of the transcription factor CCAAT enhancer‑binding protein homologous protein (CHOP). NAC, a ROS scavenger, reduced the effect of ICA on ERK activation, DR induction and sensitization of TRAIL‑induced apoptosis. In addition, ICA enhanced the effects of TRAIL to reduce tumor growth in an invivo xenograft mouse model. Overall, the present study provided evidence that ICA sensitized tumor cells to TRAIL‑induced apoptosis via ROS‑, ERK‑ and CHOP‑mediated upregulation of DR5 and DR4. Based on these results, it is suggested that the antitumor activity of ICA and TRAIL co‑treatment invitro and invivo may be used as an effective therapeutic agent in chemotherapy.