Boosting Apoptotic Cell Clearance by Colonic Epithelial Cells Attenuates Inflammation In Vivo.

Few apoptotic corpses are seen even in tissues with high cellular turnover, leading to the notion that the capacity for engulfment in vivo is vast. Whether corpse clearance can be enhanced in vivo for potential benefit is not known. In a colonic inflammation model, we noted that the expression of the phagocytic receptor Bai1 was progressively downmodulated. Consistent with this, BAI1-deficient mice had more pronounced colitis and lower survival, with many uncleared apoptotic corpses and inflammatory cytokines within the colonic epithelium. When we engineered and tested transgenic mice overexpressing BAI1, these had fewer apoptotic cells, reduced inflammation, and attenuated disease. Boosting BAI1-mediated uptake by intestinal epithelial cells (rather than myeloid cells) was important in attenuating inflammation. A signaling-deficient BAI1 transgene could not provide a similar benefit. Collectively, these complementary genetic approaches showed that cell clearance could be boosted in vivo, with potential to regulate tissue inflammation in specific contexts.

Genetic requirement for Mycl and efficacy of RNA Pol I inhibition in mouse models of small cell lung cancer.

Small cell lung cancer (SCLC) is a devastating neuroendocrine carcinoma. MYCL (L-Myc) is frequently amplified in human SCLC, but its roles in SCLC progression are poorly understood. We isolated preneoplastic neuroendocrine cells from a mouse model of SCLC and found that ectopic expression of L-Myc, c-Myc, or N-Myc conferred tumor-forming capacity. We focused on L-Myc, which promoted pre-rRNA synthesis and transcriptional programs associated with ribosomal biogenesis. Deletion of Mycl in two genetically engineered models of SCLC resulted in strong suppression of SCLC. The high degree of suppression suggested that L-Myc may constitute a therapeutic target for a broad subset of SCLC. We then used an RNA polymerase I inhibitor to target rRNA synthesis in an autochthonous Rb/p53-deleted mouse SCLC model and found significant tumor inhibition. These data reveal that activation of RNA polymerase I by L-Myc and other MYC family proteins provides an axis of vulnerability for this recalcitrant cancer.

Emerging Immune Checkpoint Molecules on Cancer Cells: CD24 and CD200.

Cancer immunotherapy strategies are based on the utilization of immune checkpoint inhibitors to instigate an antitumor immune response. The efficacy of immune checkpoint blockade, directed at adaptive immune checkpoints, has been demonstrated in select cancer types. However, only a limited subset of patients has exhibited definitive outcomes characterized by a sustained response after discontinuation of therapy. Recent investigations have highlighted the significance of immune checkpoint molecules that are overexpressed in cancer cells and inhibit myeloid lineage immune cells within a tumor microenvironment. These checkpoints are identified as potential targets for anticancer immune responses. Notably, the immune checkpoint molecules CD24 and CD200 have garnered attention owing to their involvement in tumor immune evasion. CD24 and CD200 are overexpressed across diverse cancer types and serve as signaling checkpoints by engaging their respective receptors, Siglec-10 and CD200 receptor, which are expressed on tumor-associated myeloid cells. In this review, we summarized and discussed the latest advancements and insights into CD24 and CD200 as emergent immune checkpoint moieties, further delving into their therapeutic potentials for cancer treatment.

Ocular syphilis on the rise: a 10-year analysis from 2010 to 2020.

PURPOSE: The purpose of the study was to evaluate the incidence of ocular syphilis as well as diagnostic parameters, comorbidities, and visual outcomes over a 10-year time period in West Virginia. METHODS: A retrospective chart review included 25 eyes of 17 patients with ocular syphilis between 2010 and 2020. RESULTS: The incidence of systemic syphilis at a large tertiary referral center has increased from 27 cases in 2010 to 105 cases in 2020. Seventeen patients were identified with ocular syphilis. Bilaterality was present in 47.1% of cases. In this study, 70.6% of patients were male and 29.4% were female. The median age of presentation was 40.2 years (range 21-63). Panuveitis was the most common (60.0%) followed by isolated anterior uveitis (16.0%), chorioretinitis (12.0%), inner retinitis (4.0%), and papillitis (8.0%). Forty percent of patients had visual acuity worse than 20/400 on presentation. Post-treatment visual acuity improved in all patients. Rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TP-PA) tests were positive in 84.6% and 100% of cases, respectively. CSF venereal disease research laboratory (VDRL) was positive in 36.4%, CSF pleocytosis was present in 72.7%, and elevated CSF protein was observed in 81.8%. Human immunodeficiency virus (HIV) co-infection was present in 31.3%. A majority of patients experienced maculopapular rash and/or history of genital chancre. The anatomic classification of presenting uveitis (anterior, intermediate, posterior, and panuveitis) did not correlate with clinical variables including age, gender, HIV status, serologic test, presence of rash, or year of diagnosis (p > 0.05). CONCLUSION: Ocular syphilis is becoming increasingly prevalent and can present with a variety of ocular findings; therefore, it should be considered in the differential diagnosis for patients with ocular inflammation. Visual prognosis is excellent with timely diagnosis and treatment.

Structural basis for the substrate specificity of an S-formylglutathione hydrolase derived from Variovorax sp. PAMC 28711.

S-Formylglutathione hydrolase was originally known to catalyze the hydrolysis of S-formylglutathione to formate and glutathione. However, this enzyme has a broader esterase activity toward substrates containing thioester and ester bonds. In a previous study, we identified a new S-formylglutathione hydrolase (VaSFGH) gene in the Antarctic bacterium Variovorax sp. PAMC 28711, and recombinant VaSFGH protein was purified and characterized. Previous enzyme activity assays showed that VaSFGH has high activity, especially toward short-chain p-nitrophenyl esters (C2-C4). In this study, we determined the crystal structure of substrate-free VaSFGH at a resolution of 2.38 Å. In addition, p-nitrophenyl ester-bound VaSFGH structure models were generated by molecular docking simulations to obtain structural evidence of its substrate specificity. Comparative structural analysis of the apo-form and p-nitrophenyl ester-bound VaSFGH model structures revealed that large substrates could not bind inside the hydrophobic substrate-binding pocket because of the intrinsically static and relatively small substrate-binding pocket size of VaSFGH. This study provides useful information for further protein engineering of SFGHs for industrial use.

Wistin Exerts an Anti-Inflammatory Effect via Nuclear Factor-κB and p38 Signaling Pathways in Lipopolysaccharide-Stimulated RAW264.7 Cells.

Inflammation is an immune response to cellular damage caused by various stimuli (internal or external) and is essential to human health. However, excessive inflammatory responses may be detrimental to the host. Considering that the existing drugs for the treatment of inflammatory diseases have various side effects, such as allergic reactions, stomach ulcers, and cardiovascular problems, there is a need for research on new anti-inflammatory agents with low toxicity and fewer side effects. As 4',6-dimethoxyisoflavone-7-O-ß-d-glucopyranoside (wistin) is a phytochemical that belongs to an isoflavonoid family, we investigated whether wistin could potentially serve as a novel anti-inflammatory agent. In this study, we found that wistin significantly reduced the production of nitric oxide and intracellular reactive oxygen species in lipopolysaccharide-stimulated RAW 264.7 cells. Moreover, wistin reduced the mRNA levels of pro-inflammatory enzymes (inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2)) and cytokines (interleukin (IL)-1ß and IL-6) and significantly reduced the protein expression of pro-inflammatory enzymes (iNOS and COX-2). Furthermore, wistin reduced the activation of the nuclear factor-κB and p38 signaling pathways. Together, these results suggest that wistin is a prospective candidate for the development of anti-inflammatory drugs.

The microbiological spectrum, antimicrobial resistance pattern, and visual outcomes of endogenous endophthalmitis in West Virginia 2009-2019.

PURPOSE: To report the microbiological spectrum, antimicrobial resistance patterns, and visual outcomes in patients with endogenous endophthalmitis (EE). METHODS: This was a retrospective study of 50 patients with culture-positive EE managed in a tertiary referral center between October 2009 and 2019. Clinical, microbiology analysis, and antimicrobial resistance were reviewed. A multivariable linear regression analysis was used for identifying risk factors associated with worse visual outcomes. RESULTS: Fifty organisms were identified, 62% bacterial and 38% fungal. The most common bacterial organism was Staphylococcus aureus (75% methicillin resistant), and Candida was the most common fungal species. Multidrug resistance was observed in methicillin-resistant Staphylococcus aureus (MRSA) isolates against clindamycin, daptomycin, and fluoroquinolones. The distributions of the final visual acuity (VA) between the bacterial and fungal groups were significantly different, and the visual outcomes in the bacterial group tended to be worse (p = 0.01). The distributions of enucleation status were significantly higher in bacterial EE (35%) than fungal EE (5.3%) (p = 0.02). Results from the multivariable linear regression analysis revealed that older age was significantly associated with worse visual outcome (coef = 0.03; p = 0.02), while fungal infections were associated with better outcomes (coef = - 0.87; p = 0.01). Intravenous drug use (coef = 0.87; p = 0.054) was a marginally significant factor associated with worse visual outcomes. CONCLUSION: There was a higher prevalence of bacterial organisms than fungal species among EE. Bacterial EE was associated with worse visual outcomes and higher enucleation rates than fungal EE. Multidrug resistance was prevalent among MRSA isolates. Older age and intravenous drug use may be factors associated with poor prognosis.

Mortality risk associated with endophthalmitis in West Virginia.

PURPOSE: To explore how endophthalmitis presented from 2009 to 2019 in a West Virginia population particularly affected by the national opioid crisis. The analysis explores the relationship between the type of endophthalmitis and mortality, accounting for factors including age, gender, type of organism, and intravenous drug use (IVDU). METHODS: The electronic health record of West Virginia University (WVU) Medicine was queried for all patients managed for endophthalmitis from October 2009 to October 2019. For each of the included subjects, age, gender, history of IVDU, culture results, concomitant endocarditis, type of endophthalmitis, and the date of diagnosis were extracted. Mortality data were obtained from WVU's electronic medical record, the Social Security Death Index, and public obituaries. Mortality results were represented by a Kaplan-Meier Survival curve following each patient for one year from the date of diagnosis. Results were analyzed using unadjusted and adjusted Cox Proportional Hazard models. RESULTS: One-year mortality was 14 out of 113 endogenous cases (12.4%) compared to 6 out of 173 exogenous cases (3.5%). Endogenous endophthalmitis cases had significantly higher mortality than exogenous ones within one year of diagnosis (p = 0.0034). The unadjusted Cox proportional hazards model revealed that the type of endophthalmitis (endogenous vs. exogenous) was the only variable with a significant impact on 1-year mortality with a hazard ratio of 3.78 (p = 0.01). However, the hazard ratio for endogenous infections rose to 10.91 (CI 3.544-33.595) when the other variables of age, gender, organism, and IVDU were controlled (p < 0.01). The Cox proportional hazard ratios for age group, gender, organism type, and history of IVDU were not significantly different when adjusted for all other variables. CONCLUSION: Endogenous cases, which were significantly overrepresented in West Virginia, were associated with a significantly higher 1-year mortality rate than the exogenous ones. Age, gender, organism type, and history of IVDU have less, if any, modifying effect on mortality.

Phytochemicals as Anti-Inflammatory Agents in Animal Models of Prevalent Inflammatory Diseases.

Phytochemicals are known to have anti-inflammatory effects in vitro and in vivo, such as in inflammatory disease model systems. Inflammation is an essential immune response to exogenous stimuli such as infection and injury. Although inflammation is a necessary host-defense mechanism, chronic inflammation is associated with the continuous local or systemic release of inflammatory mediators, non-cytokine mediators, such as ROS and NO, and inflammatory cytokines are strongly implicated in the pathogenesis of various inflammatory disorders. Phytochemicals that exhibit anti-inflammatory mechanisms that reduce sustained inflammation could be therapeutic candidates for various inflammatory diseases. These phytochemicals act by modulating several main inflammatory signaling pathways, including NF-κB, MAPKs, STAT, and Nrf-2 signaling. Here, we discuss the characteristics of phytochemicals that possess anti-inflammatory activities in various chronic inflammatory diseases and review the molecular signaling pathways altered by these anti-inflammatory phytochemicals, with a focus on transcription factor pathways. Furthermore, to evaluate the phytochemicals as drug candidates, we translate the effective doses of phytochemicals in mice or rat disease models into the human-relevant equivalent and compare the human-relevant equivalent doses of several phytochemicals with current anti-inflammatory drugs doses used in different types of chronic inflammatory diseases.

Structural insights into the enzyme specificity of a novel ω-transaminase from the thermophilic bacterium Sphaerobacter thermophilus.

Transaminases are pyridoxal 5'-phosphate-dependent enzymes that reversibly catalyze transamination reactions from an amino group donor substrate to an amino group acceptor substrate. ω-Transaminases (ωTAs) utilize compounds with an amino group not at α-carbon position as their amino group donor substrates. Recently, a novel ωTA with broad substrate specificity and high thermostability from the thermophilic bacterium Sphaerobacter thermophilus (St-ωTA) has been reported. Although St-ωTA has been biochemically characterized, little is known about its determinants of substrate specificity. In the present study, we determined the crystal structure of St-ωTA at 1.9 Šresolution to clarify in detail its mechanism of substrate recognition. The structure of St-ωTA revealed that it has a voluminous active site resulting from the unique spatial arrangement of residues comprising its active site. In addition, our molecular docking simulation results suggest that substrate compounds may bind to active site residues via electrostatic interactions or hydrophobic interactions that can be induced by subtle rearrangements of active site residues. On the basis of these structural analyses, we propose a plausible working model of the enzymatic mechanism of St-ωTA. Our results provide profound structural insights into the substrate specificity of St-ωTA and extend the boundaries of knowledge of TAs.

Structural transformation-mediated dimerization of caspase recruitment domain revealed by the crystal structure of CARD-only protein in frog virus 3.

Caspase recruitment domain (CARD)-only proteins (COPs), regulate apoptosis, inflammation, and innate immunity. They inhibit the assembly of NOD-like receptor complexes such as the inflammasome and NODosome, which are molecular complexes critical for caspase-1 activation. COPs are known to interact with either caspase-1 CARD or RIP2 CARD via a CARD-CARD interaction, and inhibit caspase-1 activation or further downstream signaling. In addition to the human COPs, Pseudo-ICE, INCA, and ICEBERG, several viruses also contain viral COPs that help them escape the host immune system. To elucidate the molecular mechanism of host immunity inhibition by viral COPs, we solved the structure of a viral COP for the first time. Our structure showed that viral COP forms a structural transformation-mediated dimer, which is unique and has not been reported in any structural study of a CARD domain. Based on the current structure, and the previously solved structures of other death domain superfamily members, we propose that structural transformation-mediated dimerization might be a new strategy for dimer assembly in the death domain superfamily.

Crystal structure of a transcription factor, GerE (PaGerE), from spore-forming bacterium Paenisporosarcina sp. TG-14.

In cold and harsh environments such as glaciers and sediments in ice cores, microbes can survive by forming spores. Spores are composed of a thick coat protein, which protects against external factors such as heat-shock, high salinity, and nutrient deficiency. GerE is a key transcription factor involved in spore coat protein expression in the mother cell during sporulation. GerE regulates transcription during the late sporulation stage by directly binding to the promoter of cotB gene. Here, we report the crystal structure of PaGerE at 2.09 Šresolution from Paenisporosarcina sp. TG-14, which was isolated from the Taylor glacier. The PaGerE structure is composed of four α-helices and adopts a helix-turn-helix architecture with 68 amino acid residues. Based on our DNA binding analysis, the PaGerE binds to the promoter region of CotB to affect protein expression. Additionally, our structural comparison studies suggest that DNA binding by PaGerE causes a conformational change in the α4-helix region, which may strongly induce dimerization of PaGerE.

Phosphatidylserine receptor BAI1 and apoptotic cells as new promoters of myoblast fusion.

Skeletal muscle arises from the fusion of precursor myoblasts into multinucleated myofibres. Although conserved transcription factors and signalling proteins involved in myogenesis have been identified, upstream regulators are less well understood. Here we report an unexpected discovery that the membrane protein BAI1, previously linked to recognition of apoptotic cells by phagocytes, promotes myoblast fusion. Endogenous BAI1 expression increased during myoblast fusion, and BAI1 overexpression enhanced myoblast fusion by means of signalling through ELMO/Dock180/Rac1 proteins. During myoblast fusion, a fraction of myoblasts within the population underwent apoptosis and exposed phosphatidylserine, an established ligand for BAI1 (ref. 3). Blocking apoptosis potently impaired myoblast fusion, and adding back apoptotic myoblasts restored fusion. Furthermore, primary human myoblasts could be induced to form myotubes by adding apoptotic myoblasts, even under normal growth conditions. Mechanistically, apoptotic cells did not directly fuse with the healthy myoblasts, rather the apoptotic cells induced a contact-dependent signalling with neighbours to promote fusion among the healthy myoblasts. In vivo, myofibres from Bai1(-/-) mice are smaller than those from wild-type littermates. Muscle regeneration after injury was also impaired in Bai1(-/-)mice, highlighting a role for BAI1 in mammalian myogenesis. Collectively, these data identify apoptotic cells as a new type of cue that induces signalling via the phosphatidylserine receptor BAI1 to promote fusion of healthy myoblasts, with important implications for muscle development and repair.

Predicting visual function after an ocular bee sting.

PURPOSE: To report a case of toxic optic neuropathy caused by an ocular bee sting. METHODS: Case report and literature review. RESULTS: A 44-year-old female presented with no light perception vision 2 days after a corneal bee sting in her right eye. She was found to have diffuse cornea edema with overlying epithelial defect and a pinpoint penetrating laceration at 6 o'clock. There was an intense green color to the cornea. The pupil was fixed and dilated with an afferent pupillary defect. A small hyphema was seen, and a dense white cataract had formed. A diagnosis of toxic endophthalmitis with associated toxic optic neuropathy was made. The patient underwent pars plana vitrectomy and lensectomy with anterior chamber washout. She was also placed on systemic broad-spectrum antibiotics. She had noted clinical improvement over the course of her hospitalization and was discharged with light perception vision. A corneal opacity precluded viewing of the fundus. We utilized ganzfeld electroretinography and flash visual evoked potentials (2 and 10 Hz) to assess the visual function. Both tests were normal and predicted improvement following restorative surgery. She underwent a secondary lens implantation with penetrating keratoplasty 7 months later. This was followed by an epiretinal membrane peel 1 year after the bee sting. Her best corrected visual acuity improved to 20/80. CONCLUSION: Toxic endophthalmitis and toxic optic neuropathy can be complications of ocular bee sting. We discuss the management of this rare occurrence and the role of electroretinographic testing and visual evoked potentials in predicting visual outcome.

Structure-Based Classification and Anti-Cancer Effects of Plant Metabolites.

A variety of malignant cancers affect the global human population. Although a wide variety of approaches to cancer treatment have been studied and used clinically (surgery, radiotherapy, chemotherapy, and immunotherapy), the toxic side effects of cancer therapies have a negative impact on patients and impede progress in conquering cancer. Plant metabolites are emerging as new leads for anti-cancer drug development. This review summarizes these plant metabolites with regard to their structures and the types of cancer against which they show activity, organized by the organ or tissues in which each cancer forms. This information will be helpful for understanding the current state of knowledge of the anti-cancer effects of various plant metabolites against major types of cancer for the further development of novel anti-cancer drugs.

Structural aspects of transglutaminase 2: functional, structural, and regulatory diversity.

Transglutaminase 2 (TG2) is a multi-functional protein that has both protein cross-linking and guanosine 5'-triphosphate (GTP) hydrolysis activities. The activities of this protein are controlled by many cellular factors, including calcium (Ca2+) and GTP, and have been implicated in several physiological activities, including apoptosis, angiogenesis, wound healing, cellular differentiation, neuronal regeneration, and bone development. TG2 is linked to many human diseases such as inflammatory disease, celiac disease, neurodegenerative disease, diabetes, tissue fibrosis, and various cancers and is one of the most dynamic enzymes in terms of its functions, structures, and regulatory mechanisms. The aim of this review was to summarize the functional, structural, and regulatory diversity of TG2, with a particular focus on the structure of TG2.

The Role of Kinase Modulators in Cellular Senescence for Use in Cancer Treatment.

Recently, more than 30 small molecules and eight monoclonal antibodies that modulate kinase signaling have been approved for the treatment of several pathological conditions, including cancer, idiopathic pulmonary fibrosis, and rheumatoid arthritis. Among them, kinase modulators have been a primary focus for use in cancer treatment. Cellular senescence is believed to protect cells from tumorigenesis by irreversibly halting cell cycle progression and avoiding the growth of damaged cells and tissues. Senescence can also contribute to tumor suppression and be utilized as a mechanism by anti-cancer agents. Although the role of kinase modulators in cancer treatment and their effects on senescence in tumor development have been extensively studied, the relationship between kinase modulators for cancer treatment and senescence has not been fully discussed. In this review, we discuss the pro- and anti-tumorigenesis functions of senescence and summarize the key roles of kinase modulators in the regulation of senescence against tumors.

Adhesion GPCRs as Modulators of Immune Cell Function.

Immune cells express several adhesion G protein-coupled receptors (aGPCRs), including the ADGRE subfamily members EMR1 (F4/80, ADGRE1), EMR2 (ADGRE2), EMR3 (ADGRE3), EMR4 (FIRE, ADGRE4), and CD97 (ADGRE5), the ADGRB subfamily member BAI1 (ADGRB1), and the ADGRG subfamily members GPR56 (ADGRG1), GPR97 (Pb99, ADGRG3), and GPR114 (ADGRG5). Expression of these molecules in hematopoietic stem and progenitor cells, monocytes/macrophages (Mφs), dendritic cells, granulocytes, and lymphocytes depends on lineage diversification and maturation, making them suitable markers for individual leukocyte subsets (e.g., F4/80 on mouse Mφs). Recent studies revealed intriguing activities of aGPCRs in tolerance induction (EMR1), granulopoiesis (CD97), engulfment of apoptotic cells and bacteria (BAI1), hematopoietic stem cell formation (GPR56), and control of cytotoxicity (GPR56). Here, we review these findings and discuss their biological and translational implications.

Endothelial deletion of phospholipase D2 reduces hypoxic response and pathological angiogenesis.

OBJECTIVE: Aberrant regulation of the proliferation, survival, and migration of endothelial cells (ECs) is closely related to the abnormal angiogenesis that occurs in hypoxia-induced pathological situations, such as cancer and vascular retinopathy. Hypoxic conditions and the subsequent upregulation of hypoxia-inducible factor-1α and target genes are important for the angiogenic functions of ECs. Phospholipase D2 (PLD2) is a crucial signaling mediator that stimulates the production of the second messenger phosphatidic acid. PLD2 is involved in various cellular functions; however, its specific roles in ECs under hypoxia and in vivo angiogenesis remain unclear. In the present study, we investigated the potential roles of PLD2 in ECs under hypoxia and in hypoxia-induced pathological angiogenesis in vivo. APPROACH AND RESULTS: Pld2 knockout ECs exhibited decreased hypoxia-induced cellular responses in survival, migration, and thus vessel sprouting. Analysis of hypoxia-induced gene expression revealed that PLD2 deficiency disrupted the upregulation of hypoxia-inducible factor-1α target genes, including VEGF, PFKFB3, HMOX-1, and NTRK2. Consistent with this, PLD2 contributed to hypoxia-induced hypoxia-inducible factor-1α expression at the translational level. The roles of PLD2 in hypoxia-induced in vivo pathological angiogenesis were assessed using oxygen-induced retinopathy and tumor implantation models in endothelial-specific Pld2 knockout mice. Pld2 endothelial-specific knockout retinae showed decreased neovascular tuft formation, despite a larger avascular region. Tumor growth and tumor blood vessel formation were also reduced in Pld2 endothelial-specific knockout mice. CONCLUSIONS: Our findings demonstrate a novel role for endothelial PLD2 in the survival and migration of ECs under hypoxia via the expression of hypoxia-inducible factor-1α and in pathological retinal angiogenesis and tumor angiogenesis in vivo.

Digitoxin sensitizes glioma cells to TRAIL-mediated apoptosis by upregulation of death receptor 5 and downregulation of survivin.

Glioblastoma multiforme is the most lethal and aggressive astrocytoma among primary brain tumors in adults. However, most glioblastoma cells have been reported to be resistant to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. Here, we have shown that digitoxin (DT), a clinically approved cardiac glycoside for heart failure, can induce TRAIL-mediated apoptosis of glioblastoma cells. DT in noncytotoxic doses (20 nmol/l) can increase TRAIL-induced apoptosis in TRAIL-resistant U87MG glioblastoma cells. Treatment with DT led to apoptosis and a robust reduction in the levels of the antiapoptotic protein survivin by inducing its proteasomal degradation; however, it did not affect the levels of many other apoptosis regulators. Moreover, silencing survivin with small interfering RNAs sensitized glioma cells to TRAIL-induced apoptosis, underscoring the functional role of survivin depletion in the TRAIL-sensitizing actions of DT. We demonstrate that inactivation of survivin and death receptor 5 expression by DT is sufficient to restore TRAIL sensitivity in resistant glioma cells. Our results suggest that combining DT with TRAIL treatments may be useful in the treatment of TRAIL-resistant glioma cells.