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Recurrent waves of COVID19 remain a major global health concern. Repurposing either FDA-approved or clinically advanced drug candidates can save time and effort required for validating the safety profile and FDA approval. However, the selection of appropriate screening approaches is key to identifying novel candidate drugs with a higher probability of clinical success. Here, we report a rapid, stratified two-step screening approach using pseudovirus entry inhibition assay followed by an infectious prototypic SARS CoV2 cytotoxic effect inhibition assay in multiple cell lines. Using this approach, we screened a library of FDA-approved and clinical-stage drugs and identified four compounds, apilimod, berbamine, cepharanthine and (S)-crizotinib which potently inhibited SARS CoV2-induced cell death. Importantly, these drugs exerted similar inhibitory effect on the delta and omicron variants although they replicated less efficiently than the prototypic strain. Apilimod is currently under clinical trial (NCT04446377) for COVID19 supporting the validity and robustness of our screening approach.

The majority of patients with colon cancer will develop advanced disease, with the liver being the most common site of metastatic disease. Patients with increased numbers of tumor-infiltrating lymphocytes in primary colon tumors and liver metastases have improved outcomes. However, the molecular factors that could empower antitumor immune responses in this setting remain to be elucidated. We reported that the immunostimulatory cytokine LIGHT (TNFSF14) in the microenvironment of colon cancer metastases associates with improved patient survival, and here we demonstrate in an immunocompetent murine model that colon tumors expressing LIGHT stimulate lymphocyte proliferation and tumor cell–specific antitumor immune responses. In this model, increasing LIGHT expression in the microenvironment of either primary tumors or liver metastases triggered regression of established tumors and slowed the growth of liver metastases, driven by cytotoxic T-lymphocyte–mediated antitumor immunity. These responses corresponded with significant increases in tumor-infiltrating lymphocytes and increased expression of lymphocyte-homing signals in the metastatic tumors. Furthermore, we demonstrated evidence of durable tumor-specific antitumor immunity. In conclusion, increasing LIGHT expression increased T-cell proliferation, activation, and infiltration, resulting in enhanced tumor-specific immune-mediated tumor regressions in primary tumors and colorectal liver metastases. Mechanisms to increase LIGHT in the colon cancer microenvironment warrant further investigation and hold promise as an immunotherapeutic strategy. Cancer Res; 77(8); 1880–91. ©2017 AACR.

Supplemental Figure Legend from LIGHT Elevation Enhances Immune Eradication of Colon Cancer Metastases

Supplemental figure 1 presents proliferation, apoptosis, and migration assays demonstrating that LIGHT expressing colon cancer cell lines maintain wild-type characteristics. Supplemental figure 2 provides evidence that LIGHT expressing colorectal liver metastases demonstrate increased dendritic cell infiltration and increased immunocyte homing signals.

The IG20 gene undergoes alternative splicing resulting in the differential expression of six putative splice variants. Four of these (IG20pa, MADD, IG20-SV2, and DENN-SV) are expressed in virtually all human tissues. However, investigations examining alternative splicing of the IG20 gene to date have been largely limited to nonneural malignant and nonmalignant cells. In this study, we investigated the expression of alternative splice isoforms of the IG20 gene in human neuroblastoma cells. We found that six IG20 splice variants (IG20-SVs) were expressed in two human neuroblastoma cell lines (SK-N-SH and SH-SY5Y), highlighted by the expression of two unique splice isoforms (i.e., KIAA0358 and IG20-SV4). Similarly, we found enriched expression of these two IG20-SVs in human neural tissues derived from cerebral cortex, hippocampus, and, to a lesser extent, spinal cord. Using gain-of-function studies and siRNA technology, we determined that these “neural-enriched isoforms” exerted significant and contrasting effects on vulnerability to apoptosis in neuroblastoma cells. Specifically, expression of KIAA0358 exerted a potent antiapoptotic effect in both the SK-N-SH and SH-SY5Y neuroblastoma cell lines, whereas expression of IG20-SV4 had proapoptotic effects directly related to the activation of caspase-8 in these cells, which have minimal or absent constitutive caspase-8 expression. These data indicate that the pattern of expression of these neural-enriched IG20-SVs regulates the expression and activation of caspase-8 in certain neuroblastoma cells, and that manipulation of IG20-SV expression pattern may represent a potent therapeutic strategy in the therapy of neuroblastoma and perhaps other cancers. [Cancer Res 2008;68(18):7352–61]

Supplementary Figure 3 from Regulation of Apoptosis and Caspase-8 Expression in Neuroblastoma Cells by Isoforms of the IG20 Gene

Supplementary Figure 1 from Regulation of Apoptosis and Caspase-8 Expression in Neuroblastoma Cells by Isoforms of the IG20 Gene

Supplementary Legends 1-5 from Regulation of Apoptosis and Caspase-8 Expression in Neuroblastoma Cells by Isoforms of the IG20 Gene

Supplementary Figure 4 from Regulation of Apoptosis and Caspase-8 Expression in Neuroblastoma Cells by Isoforms of the IG20 Gene

Supplementary Figure 2 from Regulation of Apoptosis and Caspase-8 Expression in Neuroblastoma Cells by Isoforms of the IG20 Gene

Supplementary Figure 5 from Regulation of Apoptosis and Caspase-8 Expression in Neuroblastoma Cells by Isoforms of the IG20 Gene

INTRODUCTION: The generation of long-term durable tumor immunity and prolonged disease-free survival depends on the ability to generate and support CD8+ central memory T-cells. Microsatellite-stable colon cancer is resistant to currently available immunotherapies, thus, development of novel mechanisms to increase both lymphocyte infiltration and central memory formation are needed to improve outcomes in these patients. We have previously demonstrated that both Interleukin-2 (IL-2) and LIGHT (TNFSF14) independently enhance anti-tumor immune responses, and hypothesize that combination immunotherapy may increase the CD8+ central memory T-cell response. METHODS: CT26 murine colorectal cancer tumors were established in syngeneic mice. Tumors were treated with control, soluble, or liposomal Interleukin-2 (IL-2) at established intervals. A subset of animal tumors overexpressed tumor necrosis superfamily factor LIGHT (TNFSF14). Peripheral blood, splenic, and tumor infiltrating lymphocytes were isolated for phenotypic studies and flow cytometry. RESULTS: Tumors exposed to a combination of LIGHT and IL-2 experienced a decrease in tumor size compared to IL-2 alone that was not demonstrated in wild-type (wt) tumors or between other treatment groups. Combination exposure also increased splenic central memory CD8+ cells compared to IL-2 administration alone, while not increasing tumor-infiltrating lymphocytes. In the periphery, the combination enhanced levels of circulating CD8 T-cells and central memory T-cells, while also increasing circulating T-regulatory cells. CONCLUSIONS: Combination of IL-2, whether soluble or liposomal, with exposure to LIGHT results in increased CD8+ central memory cells in the spleen and periphery. New combination immunotherapy strategies that support both effector and memory T-cell functions are critical to enhancing durable anti-tumor responses and warrant further investigation.

Escalated innate immunity plays a critical role in SARS-CoV-2 pathology; however, the molecular mechanism is incompletely understood. Thus, we aim to characterize the molecular mechanism by which SARS-CoV-2 Spike protein advances human macrophage (Mϴ) inflammatory and glycolytic phenotypes and uncover novel therapeutic strategies. We found that human Mϴs exposed to Spike protein activate IRAK4 phosphorylation. Blockade of IRAK4 in Spike protein-stimulated Mϴs nullifies signaling of IRAK4, AKT, and baseline p38 without affecting ERK and NF-κB activation. Intriguingly, IRAK4 inhibitor (IRAK4i) rescues the SARS-CoV-2-induced cytotoxic effect in ACE2

Abstract Increased tumor infiltrating lymphocytes (TIL) are associated with improved patient responses to immunotherapy. As a result, there is interest in enhancing lymphocyte trafficking particularly to colon cancers since the majority are checkpoint blockade-resistant and microsatellite stable. Here, we demonstrate that activated T-cells (ATC) armed with anti-CD3 x anti-EGFR bispecific antibody increases TIL and mediate anti-tumor cytotoxicity while decreasing tumor cell viability. Furthermore, treatment induces endogenous anti-tumor immunity that resisted tumor rechallenge and increased memory T-cell subsets in the tumor. When combined with targeted tumor expression of the tumor necrosis factor superfamily member LIGHT, activated T-cell proliferation and infiltration were further enhanced, and human colorectal tumor regressions were observed. Our data indicate that tumor-targeted armed bispecific antibody increases TIL trafficking and is a potentially potent strategy that can be paired with combination immunotherapy to battle microsatellite stable colon cancer. Significance Enhancing trafficking of tumor infiltrating lymphocytes (TILs) to solid tumors has been shown to improve outcomes. Unfortunately, few strategies have been successful in the clinical setting for solid tumors, particularly for “cold” microsatellite stable colon cancers. In order to address this gap in knowledge, this study combined TNFSF14/LIGHT immunomodulation with a bispecific antibody armed with activated T-cells targeted to the tumor. This unique T-cell trafficking strategy successfully generated anti-tumor immunity in a microsatellite stable colon cancer model, stimulated T-cell infiltration, and holds promise as a combination immunotherapy for treating advanced and metastatic colorectal cancer.

LIGHT, also known as tumor-necrosis factor (TNF) superfamily member 14 (TNFSF14), is predominantly expressed on activated immune cells and some tumor cells. LIGHT is a pivotal regulator both for recruiting and activating immune cells in the tumor lesions. In this study, we armed human telomerase reverse transcriptase (TERT) promoter controlled oncolytic adenovirus with LIGHT to generate rAd.Light. rAd.Light effectively transduced both human and mouse breast tumor cell lines in vitro, and expressed LIGHT protein on the surface of tumor cells. Both rAd.Null, and rAd.Light could replicate in human breast cancer cells, and produced cytotoxicity to human and mouse mammary tumor cells. rAd.Light induced apoptosis resulting in tumor cell death. Using a subcutaneous model of 4T1 cells in BALB/c mice, rAd.Light was delivered intratumorally to evaluate the anti-tumor responses. Both rAd.Light and rAd.Null significantly inhibited the tumor growth, but rAd.Light produced much stronger anti-tumor effects. Histopathological analysis showed the infiltration of T lymphocytes in the tumor tissues. rAd.Light also induced stronger cellular apoptosis than rAd.Null in the tumors. Interestingly, on day 15, compared to rAd.Null, there was a significant reduction of Tregs following rAd.Light treatment. rAd.Light significantly increased Th1 cytokine interleukin (IL)-2 expression, and reduced Th2 cytokines expression, such as transforming growth factor β (TGF-β) and IL-10 in the tumors. These results suggest rAd.Light induced activation of anti-tumor immune responses. In conclusion, rAd.Light produced anti-tumor effect in a subcutaneous model of breast cancer via inducing tumor apoptosis and evoking strong anti-tumor immune responses. Therefore, rAd.Light has great promise to be developed as an effective therapeutic approach for the treatment of breast cancer.

Recurrent waves of SARS CoV2 infections remain a major global health concern. Emergence of highly infectious variants with reduced sensitivity to neutralization by vaccines and monoclonal antibodies (mAb) necessitates a deeper understanding of factors involved in SARS CoV2 infections and identification of drug candidates to halt infection. Here, we determined the primacy of endosomal protease cathepsin-L in mediating SARS CoV2 entry and screened a library of well-annotated bioactive compounds for potent cathepsin-L inhibitory activity. Whilst the potent cathepsin-L inhibitors were capable of inhibiting SARS CoV2 entry and cytopathic effect (CPE) in less susceptible cell lines such as human ACE2 expressing 293T cells, these drugs failed to inhibit SARS CoV2 in highly susceptible cell lines such as human TMPRSS2 or human-ACE2-TMPRSS2 overexpressing Vero E6 cells. Only drugs with dual inhibitory effect on both host cathepsin-L and virus 3CL-Protease enzymes such as Z-FA-FMK and GC-376 were capable of inhibiting prototypic (USA-WA1/2020, Lineage A) SARS CoV2 induced CPE in highly susceptible cell lines. Moreover, these drugs inhibited delta (Lineage-B.1.617.2) and omicron (Lineage-B.1.1.529) infection with equal potency showing that the newer mutations harbored in these variants did not affect the mechanism of action of these drugs such as cathepsin-L or 3CL-Pro inhibition. Moreover, our early evidence that 3CL-Pro inhibition can effectively inhibit omicron-induced CPE in highly susceptible cell lines suggests that the recently FDA-approved oral drug, a 3CL-Pro inhibitor which is a combination of nirmatrelvir/ritonavir (Paxlovid) could be effective against omicron variant which shows reduced sensitivity to vaccines and mAb.ImportanceWe report that cathepsin-L and 3CL-Pro as major targets for designing antivirals against SARS CoV2. Dual inhibition of cathepsin-L and 3CL-Pro by GC-376 renders it effective in inhibiting SARS CoV2-induced cytopathic effect in highly susceptible cell lines. Moreover, this candidate drug is equally effective against prototypic SARS CoV2 lineage A and emerging variants such as delta and omicron which show reduced sensitivity to vaccines and monoclonal antibodies. Given the recent wave of SARS CoV2 omicron variant infection around the world, and 3CL-Pro inhibitor nirmatrelvir is one of the components of the FDA-approved Paxlovid, our findings are timely, important and should be of broad interest.

Class-switched antinuclear autoantibodies produced by T follicular helper (TFH) cell–dependent germinal center (GC) B cell response play an essential pathogenic role in lupus nephritis (LN). The role of T follicular regulatory (TFR) cells, an effector subset of CD4+Foxp3+ T regulatory cells (Tregs), which are specialized in suppressing TFH-GC response and Ab production, remains elusive in LN. Contrasting reports have shown increased/reduced circulating TFR cells in human lupus that might not accurately reflect their presence in the GCs of relevant lymphoid organs. In this study, we report a progressive reduction in TFR cells and decreased TFR/TFH ratio despite increased Tregs in the renal lymph nodes of NZBWF1/j mice, which correlated with increased GC-B cells and proteinuria onset. Cotreatment with soluble OX40L and Jagged-1 (JAG1) proteins increased Tregs, TFR cells, and TFR/TFH ratio, with a concomitant reduction in TFH cells, GC B cells, and anti-dsDNA IgG Ab levels, and suppressed LN onset. Mechanistic studies showed attenuated TFH functions and diminished GC events such as somatic hypermutation and isotype class-switching in OX40L-JAG1–treated mice. RNA sequencing studies revealed inhibition of hypoxia-inducible factor 1-α (HIF-1a) and STAT3 signaling in T conventional cells from OX40L-JAG1–treated mice, which are critical for the glycolytic flux and differentiation into TFH cell lineage. Therefore, the increased TFR/TFH ratio seen in OX40L-JAG1–treated mice could involve both impaired differentiation of TFH cells from T conventional cells and expansion of TFR cells. We show a key role for GC-TFR/TFH imbalance in LN pathogenesis and how restoring homeostatic balance can suppress LN.

In an effort to develop a new therapy for cancer and to improve antiprogrammed death inhibitor-1 (anti-PD-1) and anticytotoxic T lymphocyte-associated protein (anti-CTLA-4) responses, we have created a telomerase reverse transcriptase promoter-regulated oncolytic adenovirus rAd.sT containing a soluble transforming growth factor receptor II fused with human IgG Fc fragment (sTGFβRIIFc) gene. Infection of breast and renal tumor cells with rAd.sT produced sTGFβRIIFc protein with dose-dependent cytotoxicity. In immunocompetent mouse 4T1 breast tumor model, intratumoral delivery of rAd.sT inhibited both tumor growth and lung metastases. rAd.sT downregulated the expression of several transforming growth factor β (TGFβ) target genes involved in tumor growth and metastases, inhibited Th2 cytokine expression, and induced Th1 cytokines and chemokines, and granzyme B and perforin expression. rAd.sT treatment also increased the percentage of CD8(+) T lymphocytes, promoted the generation of CD4(+) T memory cells, reduced regulatory T lymphocytes (Tregs), and reduced bone marrow-derived suppressor cells. Importantly, rAd.sT treatment increased the percentage of CD4(+) T lymphocytes, and promoted differentiation and maturation of antigen-presenting dendritic cells in the spleen. In the immunocompetent mouse Renca renal tumor model, similar therapeutic effects and immune activation results were observed. In the 4T1 mammary tumor model, rAd.sT improved the inhibition of tumor growth and lung and liver metastases by anti-PD-1 and anti-CTLA-4 antibodies. Analysis of the human breast and kidney tumors showed that a significant number of tumor tissues expressed high levels of TGFβ and TGFβ-inducible genes. Therefore, rAd.sT could be a potential enhancer of anti-PD-1 and anti-CTLA-4 therapy for treating breast and kidney cancers.

ATC is an aggressive disease with limited therapeutic options due to drug resistance. TRAIL is an attractive anti-cancer therapy that can trigger apoptosis in a cancer cell-selective manner. However, TRAIL resistance is a major clinical obstacle for its use as a therapeutic drug. Previously, we demonstrated that MADD is a cancer cell pro-survival factor that can modulate TRAIL resistance. However, its role, if any, in overcoming TRAIL resistance in ATC is unknown. First, we characterized ATC cell lines as either TRAIL resistant, TRAIL sensitive or moderately TRAIL sensitive and evaluated MADD expression/cellular localization. We determined the effect of MADD siRNA on cellular growth and investigated its effect on TRAIL treatment. We assessed the effect of combination treatment (MADD siRNA and TRAIL) on mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) levels. The effect of combination treatment on tumor growth was assessed in vivo. We found increased levels of MADD in ATC cells relative to Nthy-ori 3-1. MADD protein localizes in the cytosol (endoplasmic reticulum and Golgi body) and membrane. MADD knockdown resulted in spontaneous cell death that was synergistically enhanced when combined with TRAIL treatment in otherwise resistant ATC cells. Combination treatment resulted in a significant reduction in MMP and enhanced generation of ROS indicating the putative mechanism of action. In an orthotopic mouse model of TRAIL-resistant ATC, treatment with MADD siRNA alone reduced tumor growth that, when combined with TRAIL, resulted in significant tumor regressions. We demonstrated the potential clinical utility of MADD knockdown in sensitizing cells to TRAIL-induced apoptosis in ATC.

Self-tolerance, the state of unresponsiveness to self-tissues/antigens, is maintained through central and peripheral tolerance mechanisms, and a breach of these mechanisms leads to autoimmune diseases. Foxp3 + T-regulatory cells (Tregs) play an essential role in suppressing autoimmune response directed against self-antigens and thereby regulate self-tolerance. Natural Tregs are differentiated in the thymus on the basis of their higher TCR-affinity to self-antigens and migrate to the periphery where they maintain peripheral tolerance. In addition, extra-thymic differentiation of induced Tregs can occur in the periphery which can control abrupt immune responses under inflammatory conditions. A defect in Treg cell numbers and/or function is found to be associated with the development of autoimmune disease in several experimental models and human autoimmune diseases. Moreover, augmentation of Tregs has been shown to be beneficial in treating autoimmunity in preclinical models, and Treg based cellular therapy has shown initial promise in clinical trials. However, emerging studies have identified an unstable subpopulation of Tregs which expresses pro-inflammatory cytokines under both homeostatic and autoimmune conditions, as well as in ex vivo cultures. In addition, clinical translation of Treg cellular therapy is impeded by limitations such as lack of easier methods for selective expansion of Tregs and higher cost associated with GMP-facilities required for cell sorting, ex vivo expansion and infusion of ex vivo expanded Tregs. Here, we discuss the recent advances in molecular mechanisms regulating Treg differentiation, Foxp3 expression and lineage stability, the role of Tregs in the prevention of various autoimmune diseases, and critically review their clinical utility for treating human autoimmune diseases.

Colorectal cancer remains a leading cause of cancer-related mortality worldwide. Metastases to the liver are often present at initial presentation and will form in most patients during their course of disease. We have previously demonstrated that enhanced trafficking and activation of tumor-infiltrating lymphocytes in colorectal liver metastases (CRLM) may improve antitumor immune responses. Thus, development of novel mechanisms to increase lymphocyte infiltration and activation are needed to improve patient outcomes.CT26 murine colorectal cancer cells were treated with physiologic levels of the potent inducer of immunogenic cell death mitoxantrone (MTX). An in situ vaccine was created with treated cells in an established model of CRLM. Cells were evaluated by flow cytometry for cell cycle evaluation and calreticulin expression. Splenic and tumor-infiltrating lymphocytes were isolated for phenotypic studies.MTX-treatment of colon cancer cells resulted in a sub-G1 peak, inhibition of G1 cell cycle progression, and increased G2/M cell fractions while simultaneously increasing dynamic exposure of calreticulin on the cell surface (P 0.05). Vaccination with MTX-treated cells resulted in significant decreases in CRLM formation associated with increased tumor-infiltrating leukocytes that displayed increased expression of the T cell surface activation marker CD69.Vaccination with MTX-treated primary colon cancer cells enhances tumor-infiltrating lymphocytes and clinical responses in CRLM.

Increased tumor infiltrating lymphocytes (TIL) are associated with improved patient responses to immunotherapy. As a result, there is interest in enhancing lymphocyte trafficking particularly to colon cancers since the majority are checkpoint blockade-resistant and microsatellite stable. Here, we demonstrate that activated T-cells (ATC) armed with anti-CD3 x anti-EGFR bispecific antibody increases TIL and mediate anti-tumor cytotoxicity while decreasing tumor cell viability. Furthermore, treatment induces endogenous anti-tumor immunity that resisted tumor rechallenge and increased memory T-cell subsets in the tumor. When combined with targeted tumor expression of the tumor necrosis factor superfamily member LIGHT, activated T-cell proliferation and infiltration were further enhanced, and human colorectal tumor regressions were observed. Our data indicate that tumor-targeted armed bispecific antibody increases TIL trafficking and is a potentially potent strategy that can be paired with combination immunotherapy to battle microsatellite stable colon cancer. SIGNIFICANCE: Enhancing trafficking of tumor infiltrating lymphocytes (TILs) to solid tumors has been shown to improve outcomes. Unfortunately, few strategies have been successful in the clinical setting for solid tumors, particularly for "cold" microsatellite stable colon cancers. In order to address this gap in knowledge, this study combined TNFSF14/LIGHT immunomodulation with a bispecific antibody armed with activated T-cells targeted to the tumor. This unique T-cell trafficking strategy successfully generated anti-tumor immunity in a microsatellite stable colon cancer model, stimulated T-cell infiltration, and holds promise as a combination immunotherapy for treating advanced and metastatic colorectal cancer.

TNF receptor superfamily comprises many T-cell costimulatory receptors, including TNFRSF1, TNFRSF2, TNFRSF4 (OX40), TNFRSF9 (4-1BB), TNFRSF18 (GITR), and TNFRSF7 (CD27). Signaling through these costimulatory stimulatory receptors can promote conventional T-cell (Tconv) proliferation, and effector functions in an antigen-dependent manner. Thus, agonistic antibodies and ligands for OX40, 4-1BB, GITR, and CD27 have been tested for inducing T-cell-mediated antitumor responses in several cancers. However, recently emerging reports show critical role for TNFR signaling in regulatory T-cell (Treg) differentiation and expansion, which might suppress effector T-cell proliferation and functions. Here, we show preferential over expression of TNFR2, OX40, 4-1BB, and GITR in Treg cells over Tconv cells, and the ability of OX40L and GITRL to induce selective proliferation of Treg cells, but not Tconv cells, in an antigen-independent manner. We describe the standard protocols used for Affymetrix gene expression profiling, T-cell isolation, and Cell Trace Violet-based cell proliferation assay.

TNF receptor superfamily comprises many T-cell costimulatory receptors, including TNFRSF1, TNFRSF2, TNFRSF4 (OX40), TNFRSF9 (4-1BB), TNFRSF18 (GITR), and TNFRSF7 (CD27). Signaling through these costimulatory stimulatory receptors can promote conventional T-cell (Tconv) proliferation, and effector functions in an antigen-dependent manner. Thus, agonistic antibodies and ligands for OX40, 4-1BB, GITR, and CD27 have been tested for inducing T-cell-mediated antitumor responses in several cancers. However, recently emerging reports show critical role for TNFR signaling in regulatory T-cell (Treg) differentiation and expansion, which might suppress effector T-cell proliferation and functions. Here, we show preferential over expression of TNFR2, OX40, 4-1BB, and GITR in Treg cells over Tconv cells, and the ability of OX40L and GITRL to induce selective proliferation of Treg cells, but not Tconv cells, in an antigen-independent manner. We describe the standard protocols used for Affymetrix gene expression profiling, T-cell isolation, and Cell Trace Violet-based cell proliferation assay.

Anaplastic thyroid cancer (ATC) is rare but with poor prognosis. TRAIL can selectively induce apoptosis in cancer cells; however, resistance is quite common. Aim of our study was to evaluate TRAIL-induced apoptosis in ATC-derived cell lines, in vitro and in vivo, and the effect of combination with tyrosine kinase inhibitors (TKIs) selective for BRAF (vemurafenib) or Akt (MK-2206). Four ATC-derived cell lines were used: C643, CAL62, HTh7, with activating mutation of RAS and copy gain of PI3K (HTh7) and, 8505C with activating mutation of BRAF. Cells were treated with TRAIL alone or in combination with vemurafenib or MK-2206. The pro-apoptotic effect of TRAIL alone or combined with TKIs was, also, evaluated in two mouse xenograft models (HTh7 and 8505C). C643, CAL62, and HTh7 cells were sensitive to TRAIL-induced apoptosis, whereas 8505C cells were resistant. Both in vitro and in vivo vemurafenib was able to increase the TRAIL-induced apoptosis in 8505C cells causing a slower tumor growth in 8505C xenograft compared to placebo, while MK-2206 did not have any additive effect on TRAIL treatment in HTh7 model. TRAIL is a promising therapeutic agent in ATC and in case of resistance vemurafenib may be a valid complementary therapy.

We have recently demonstrated that treatment of NOD mice with the epigenetic drug Trichostatin A (TSA) ameliorated myelin peptide induced progressive experimental autoimmune encephalomyelitis (P-EAE). Protection was accompanied by induction of antigen-specific T-cell tolerance in the periphery and reduced influx of T cells into the spinal cord. In this investigation, we examined whether the epigenetic drug could impact the innate immune system as well. Whereas the mature (MHC class II+) CD11b+Ly-6G+ neutrophils expanded substantially in the peripheral lymphoid compartment during the preclinical phase, the MHC class II+, CD11b+Ly-6C+ mature monocytes increased modestly throughout the disease course. Amelioration of the clinical disease by TSA treatment was accompanied by diminished abundance of CD11b+Ly-6Gdim activated neutrophils in secondary lymphoid organs and their influx into the spinal cord without affecting monocytes. Interestingly, the co-inhibitory ligand CD274+ (PD-L1+) but not CD275+ (ICOS-L+), CD39+ or CD11c+ dendritic cells were decreased in the peripheral lymphoid compartment of drug treated mice. Thus, in addition to myelin-specific T cell tolerance induction observed previously, selective repression of mature neutrophils and PD-L1+ cells is critically involved in the epigenetic regulation of P-EAE.

We have previously shown that OX40L/OX40 interaction is critical for TCR-independent selective proliferation of Foxp3+ Tregs, but not Foxp3− effector T-cells (Teff), when CD4+ T-cells are co-cultured with GM-CSF derived bone marrow dendritic cells (G-BMDCs). Events downstream of OX40L/OX40 interaction in Tregs responsible for this novel mechanism are not understood. Earlier, OX40L/OX40 interaction has been shown to stimulate CD4+ T-cells through the formation of a signalosome involving TRAF2/PKC-Ѳ leading to NF-kB activation. In this study, using CD4+ T-cells from WT and OX40−/− mice we first established that OX40 mediated activation of NF-kB was critical for this Treg proliferation. Although CD4+ T-cells from PKC-Ѳ−/− mice were also defective in G-BMDC induced Treg proliferation ex vivo, this defect could be readily corrected by adding exogenous IL-2 to the co-cultures. Furthermore, by treating WT, OX40−/−, and PKC-Ѳ−/− mice with soluble OX40L we established that OX40L/OX40 interaction was required and sufficient to induce Treg proliferation in vivo independent of PKC-Ѳ status. Although PKC-Ѳ is dispensable for TCR-independent Treg proliferation per se, it is essential for optimum IL-2 production by Teff cells. Finally, our findings suggest that OX40L binding to OX40 likely results in recruitment of TRAF1 for downstream signalling.

The long‐term usage of doxorubicin (DOX) is largely limited due to the development of severe cardiomyopathy. Many studies indicate that DOX‐induced cardiac injury is related to reactive oxygen species generation and ultimate activation of apoptosis. The role of novel mitochondrial fission protein 1 (Mtfp1) in DOX‐induced cardiotoxicity remains elusive. Here, we report the pro‐mitochondrial fission and pro‐apoptotic roles of Mtfp1 in DOX‐induced cardiotoxicity. DOX up‐regulates the Mtfp1 expression in HL‐1 cardiac myocytes. Knockdown of Mtfp1 prevents cardiac myocyte from undergoing mitochondrial fission, and subsequently reduces the DOX‐induced apoptosis by preventing dynamin 1‐like (Dnm1l) accumulation in mitochondria. In contrast, when Mtfp1 is overexpressed, a suboptimal dose of DOX can induce a significant percentage of cells to undergo mitochondrial fission and apoptosis. These data suggest that knocking down of Mtfp1 can minimize the cardiomyocytes loss in DOX‐induced cardiotoxicity. Thus, the regulation of Mtfp1 expression could be a novel therapeutic approach in chemotherapy‐induced cardiotoxicity.

One of the severe limitations of chemotherapy is the development of drug resistance. However, the mechanisms underlying chemotherapy resistance remain to be elucidated. Mitochondrial mediated apoptosis is a form of cell death induced by chemotherapy. Several chemotherapeutic agents have been shown to induce mitochondrial fission, and finally activate the apoptosis cascade in various cancer cells. Here, we report that the mitochondrial membrane protein 18 (MTP18) induced mitochondrial fragmentation in gastric cancer cells under doxorubicin (DOX) exposure. Upon over-expression of MTP18, a sub-cytotoxic dose of DOX could sensitize a significant number of cells to undergo mitochondrial fission and subsequent apoptosis. These findings suggest that MTP18 can enhance the sensitivity of gastric cancer cells to DOX. Mechanistically, we found that MTP18 enriched dynamic-related protein 1 (DRP1) accumulation in mitochondria and it was responsible for mediating DOX-induced signaling required for mitochondrial fission. Intriguingly, MTP18 expression was downregulated during DOX treatment. Thus, down-regulation of MTP18 expression could be one of the resistance factors interfering with DOX-induced apoptosis in gastric cancer cells.

Anaplastic Thyroid Cancer (ATC) is an aggressive malignancy with limited therapeutic options and dismal patient survival. We have previously shown MADD to be differentially overexpressed in multiple cancer histologies and to contribute to tumor cell growth and survival. Therefore, we targeted MADD by gene silencing, explored its effect on cellular proliferation and metastases and examined its therapeutic potential in an orthotopic ATC model in athymic nude mice. When compared to untreated control and scramble siRNA, MADD siRNA treatment inhibited the proliferative capacity of 8505C, C643 and HTH7 cells in vitro and 8505C-derived-orthotopic tumor growth in vivo. MADD ablation caused a significant reduction in cellular migration and invasion potential; clonogenic capacity; as well as, mitochondrial length and potential in vitro. This MADD siRNA-induced anti-migratory/invasive effect corresponded with inhibition of epithelial–mesenchymal transition (EMT) and Wnt signaling. Mechanistically, MADD siRNA inhibited TNFα induced activation of pERK, pGSK3β and β-catenin, suggesting that MADD knockdown might exert its anti-migratory/invasive effects, by blocking TNFα/ERK/GSK3β axis. MADD siRNA can inhibit β-catenin nuclear translocation and consequently, the expression of its target genes in ATC cells. In in vivo experiments, along with tumor regression, MADD siRNA treatment also decreased evidence of lung metastases. Immunohistochemically, MADD siRNA-treated tumor tissues exhibited a reduction in Ki67 and N-Cadherin expression, and an increase in E-Cadherin expression. In conclusion, we show the crucial role of MADD in ATC tumorigenesis and metastasis and its potential implications as a molecular target for ATC therapy.

Regulatory T cells (Tregs) play a pivotal role in immune-tolerance, and loss of Treg function can lead to the development of autoimmunity. Natural Tregs generated in the thymus substantially contribute to the Treg pool in the periphery, where they suppress self-reactive effector T cells (Teff) responses. Recently, we showed that OX40L (TNFSF4) is able to drive selective proliferation of peripheral Tregs independent of canonical antigen presentation (CAP-independent) in the presence of low-dose IL-2. Therefore, we hypothesized that OX40 signaling might be integral to the TCR-independent phase of murine and human thymic Treg (tTreg) development. Development of tTregs is a two-step process: Strong T-cell receptor (TCR) signals in combination with co-signals from the TNFRSF members facilitate tTreg precursor selection, followed by a TCR-independent phase of tTreg development in which their maturation is driven by IL-2. Therefore, we investigated whether OX40 signaling could also play a critical role in the TCR-independent phase of tTreg development. OX40(−/−) mice had significantly reduced numbers of CD25(−)Foxp3(low) tTreg precursors and CD25(+)Foxp3(+) mature tTregs, while OX40L treatment of WT mice induced significant proliferation of these cell subsets. Relative to tTeff cells, OX40 was expressed at higher levels in both murine and human tTreg precursors and mature tTregs. In ex vivo cultures, OX40L increased tTreg maturation and induced CAP-independent proliferation of both murine and human tTregs, which was mediated through the activation of AKT-mTOR signaling. These novel findings show an evolutionarily conserved role for OX40 signaling in tTreg development and proliferation, and might enable the development of novel strategies to increase Tregs and suppress autoimmunity.

Multiple sclerosis (MS) afflicts genetically predisposed individuals and is associated with T lymphocyte-mediated damage to the myelin sheath of neurons in the central nervous system, resulting in severely impaired signal transmission. The mechanisms of the induction and manifestation of MS are not entirely understood. The control of autoimmune disorders is accomplished by both central tolerance in which autoreactive T lymphocytes are eliminated in the thymus and by tolerance mechanisms that operate in the periphery. Among the many mechanisms described, T regulatory (Treg) cells derived from the thymus (tTregs) and induced (iTregs) in the periphery as well as T regulatory type 1 cells (Tr1) are involved in many disease models. However, the precise details of the generation and perpetuation of these various Treg subsets and their relevance to the regulation of autoimmune diseases remain elusive. In this review, we critically analyze the current knowledge of the tolerance mechanisms involved in the regulation of MS and its animal model, experimental autoimmune encephalomyelitis.

Regulatory T-cells (Tregs) can facilitate immune evasion by tumor cells by dampening anti-tumor immunity. Reduced Teff/Treg ratio and enhanced Treg functional activity have been observed in patients suffering from different types of cancers, and attenuated Treg numbers/functions can serve as prognostic indicators. Normally, Tregs play an essential role in the maintenance of immune tolerance and prevention of autoimmunity. The most common immune checkpoint blockers (ICB) targeting co-inhibitory receptors such as anti-CTLA4 (ipilimumab and tremelimumab) and anti-PD1 (pembrolizumab and nivolumab)/anti-PD-L1 (atezolizumab) have achieved unprecedented success in cancer treatment by facilitating an effective anti-tumor immune response, at least in part, by blocking Treg mediated immunosuppression. While ICBs have shown remarkable success in cancer immunotherapy, immune-related adverse events (IRAEs) arising from ICB have forced consideration of ways to maintain immune homeostasis post ICB treatment. Preclinical models of IRAEs have shown a negative correlation between Treg numbers and IRAEs. Therefore, understanding the "ying-yang" role of Tregs in the regulation of autoimmunity and anti-tumor immunity is critical to provoking an effective anti-tumor response while maintaining immune homeostasis. Studies aimed at developing effective approaches to minimize IRAEs without compromising anti-tumor immunity are underway. Herein, we discuss 1) the critical role of key co-inhibitory receptors on Treg homeostasis and tumor tolerance; 2) how co-receptor blockade by cancer immunotherapy can lead to autoimmune adverse events; and 3) recently emerging management strategies to minimize autoimmune adverse events arising from ICB.

Apoptosis plays a critical role in the development of myocardial infarction. Cardiomyocytes are enriched with mitochondria and excessive mitochondrial fission can trigger cellular apoptosis. Recently, the mitochondrial ubiquitin ligase (MITOL), localized in the mitochondrial outer membrane, was reported to play an important role in the regulation of mitochondrial dynamics and apoptosis. However, the underlying mechanism of its action remains uncertain. The present study was aimed at uncovering the role of MITOL in the regulation of cardiomyocyte apoptosis. Our results showed that MITOL expression was up‐regulated in cardiomyocytes in response to apoptotic stimulation. Mitochondrial ubiquitin ligase overexpression blocked dynamin‐related protein 1 accumulation in the mitochondria, and attenuated the mitochondrial fission induced by hydrogen peroxide. Conversely, MITOL knockdown sensitized cardiomyocytes to undergo mitochondrial fission, resulting in subsequent apoptosis. These findings suggest that MITOL plays a protective role against apoptosis in cardiomyocytes, and may serve as a potential therapeutic target for apoptosis‐related cardiac diseases.

Earlier, we have shown that GM-CSF derived bone marrow (BM) dendritic cells (G-BMDCs) can expand Foxp3+ regulatory T-cells (Tregs) through a TCR-independent, but IL-2 dependent mechanism that required OX40L/OX40 interaction. While some reports have shown suppression of autoimmunity upon treatment with an OX40 agonist, others have shown exacerbation of autoimmune disease instead. To better understand the basis for these differing outcomes, we compared the effects of OX40L treatment in 6-week-old pre-diabetic and 12-week-old near diabetic NOD mice. Upon treatment with OX40L, 6-week-old NOD mice remained normoglycemic and showed a significant increase in Tregs in their spleen and lymph nodes, while 12-week-old NOD mice very rapidly developed hyperglycemia and failed to show Treg increase in spleen or LN. Interestingly, OX40L treatment increased Tregs in the thymus of both age groups. However, it induced Foxp3+CD103+CD38− stable-phenotype Tregs in the thymus and reduced the frequency of autoreactive Teff cells in 6-week-old mice; while it induced Foxp3+CD103−CD38+ labile-phenotype Tregs in the thymus and increased autoreactive CD4+ T cells in the periphery of 12-week-old mice. This increase in autoreactive CD4+ T cells was likely due to either a poor suppressive function or conversion of labile Tregs into Teff cells. Using ex vivo cultures, we found that the reduction in Treg numbers in 12-week-old mice was likely due to IL-2 deficit, and their numbers could be increased upon addition of exogenous IL-2. The observed divergent effects of OX40L treatment were likely due to differences in the ability of 6- and 12-week-old NOD mice to produce IL-2.

Anaplastic thyroid cancer is an extremely hard-to-treat malignancy due to its aggressiveness, metastasis and inherent therapeutic resistance. Despite using all available armamentaria, the median survival of ATC patients remains dismal. In this regard, TNF-related apoptosis-inducing ligand (TRAIL) is known to induce cancer-specific apoptosis without affecting nontumor cells. However, development of resistance to TRAIL hampers its clinical use. One of the mechanisms of TRAIL resistance is mediated through phosphorylation of Map kinase Activating Death Domain-containing protein (MADD) by Akt. In light of this, preventing MADD phosphorylation might be a rational approach to overcome TRAIL resistance. To test this, we examined MADD expression and TRAIL sensitivity by Western blotting and active caspase-3 staining in several ATC cell lines harboring mutations in cancer driver genes including BRAF, Akt, and PTEN. MADD phosphorylation was inhibited by introducing site-directed mutations in Akt phosphorylation sites of MADD and exogenously expressing the mutant constructs to determine the effect on TRAIL-induced apoptosis. Our results showed that MADD was differentially overexpressed in all ATC cells compared to the normal thyroid tissues irrespective of their mutational landscape. Further, exogenous expression of non-phosphorylatable MADD resulted in a significantly increased TRAIL-induced apoptosis accompanied by the activation of both intrinsic and extrinsic apoptotic pathways. Thus, this study establishes a concept of prevention of MADD phosphorylation to improve TRAIL susceptibility of ATC cells as it can yield similar results as that of blocking PI3k/Akt pathway without any off-target effects. Further studies are warranted to explore specific inhibitors to target MADD phosphorylation. Note: This abstract was not presented at the conference. Citation Format: Shikha Saini, Aditi Mathur, Fei Yue, Ajay Maker, Bellur S. Prabhakar. Targeting PI3K/Akt-mediated MADD phosphorylation improves TRAIL sensitivity in anaplastic thyroid cancer [abstract]. In: Proceedings of the AACR Special Conference on Targeting PI3K/mTOR Signaling; 2018 Nov 30-Dec 8; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(10_Suppl):Abstract nr A17.

Type-1 Diabetes (T1D) is the major autoimmune disease affecting the juvenile population in which insulin-producing pancreatic β-cells are destroyed by self-reactive T-cells and B-cells. Emerging studies have identified the presence of autoantibodies and altered T-cell reactivity against several autoantigens in individuals who are at risk of developing T1D even before the clinical onset of diabetes. Whilst these findings could lead to the development of predictive biomarkers for early diagnosis, growing evidence on the generation of neoepitopes, epitope spreading and diverse antigen repertoire in T1D poses a major challenge for developing approaches to induce antigen-specific tolerance. Mechanisms of neoepitope generation include post-translational modifications of existing epitopes, aberrant translational products, peptide fusion, and differences in MHC binding registers. Here, we focus our discussion on how post-translational modifications can give rise to immunogenic neoepitopes in T1D and present our perspective on how it could affect the development of therapeutic approaches to induce antigen-specific tolerance.

We have previously shown GM-CSF derived bone-marrow dendritic cells (G-BMDCs) can induce the selective expansion of Tregs through the surface-bound molecule OX40L; however, the physiological role of this ex vivo derived DC subset remained to be elucidated. We determined GM-CSF administration to mice induced the generation of in vivo derived OX40L+ DCs, phenotypically similar to ex vivo OX40L+G-BMDCs, in the spleen, brachial lymph nodes and liver. The generation of OX40L+ DCs correlated with increased percentages of functionally suppressive Tregs in the spleen, brachial lymph nodes, and liver of GM-CSF treated mice. DCs from GM-CSF treated mice expanded Tregs in CD4+ T-cell co-cultures in an OX40L dependent manner, suggesting OX40L+ DCs may play a role in peripheral Treg homeostasis. Furthermore, comparing the transcriptome data of OX40L+ DCs to that of all immune cell types revealed OX40L+ DCs to be distinct from steady-state immune cells and, microarray analysis of OX40L+G-BMDCs and OX40L−G-BMDCs revealed higher expression of molecules that are associated with tolerogenic phenotype and could play important roles in the function of OX40L+ DCs. These findings suggest that OX40L+ DCs may represent a unique DC subset induced under inflammatory conditions that may play an essential role in maintaining Treg homeostasis.

Anaplastic Thyroid Cancer (ATC) accounts for >40% thyroid cancer-related deaths and has a dismal prognosis. In the past decade, significant efforts have been made towards understanding the pathogenesis of this disease and developing novel therapeutics. Unfortunately, effective treatment is still lacking and a more thorough understanding of ATC pathogenesis may provide new opportunities to improve ATC therapeutics. This review provides insights into ATC clinical presentation and pathology, and the putative role of genetic aberrations and alterations in molecular signaling pathways in ATC pathogenesis. We reviewed prevalent mutations, chromosomal abnormalities and fusions, epigenetic alterations and dysregulations in ATC, and highlighted several signaling cascades which appeared to be integral to ATC pathogenesis. Moreover, these features offer insights into de-differentiated, aggressive and drug-resistant phenotype of ATC, and thus may help in exploring potential new molecular targets for developing novel therapeutics.

The immune system ensures optimum T-effector (Teff) immune responses against invading microbes and tumor antigens while preventing inappropriate autoimmune responses against self-antigens with the help of T-regulatory (Treg) cells. Thus, Treg and Teff cells help maintain immune homeostasis through mutual regulation. While Tregs can contribute to tumor immune evasion by suppressing anti-tumor Teff response, loss of Treg function can result in Teff responses against self-antigens leading to autoimmune disease. Thus, loss of homeostatic balance between Teff/Treg cells is often associated with both cancer and autoimmunity. Co-stimulatory and co-inhibitory receptors, collectively known as co-signaling receptors, play an indispensable role in the regulation of Teff and Treg cell expansion and function and thus play critical roles in modulating autoimmune and anti-tumor immune responses. Over the past three decades, considerable efforts have been made to understand the biology of co-signaling receptors and their role in immune homeostasis. Mutations in co-inhibitory receptors such as CTLA4 and PD1 are associated with Treg dysfunction, and autoimmune diseases in mice and humans. On the other hand, growing tumors evade immune surveillance by exploiting co-inhibitory signaling through expression of CTLA4, PD1 and PDL-1. Immune checkpoint blockade (ICB) using anti-CTLA4 and anti-PD1 has drawn considerable attention towards co-signaling receptors in tumor immunology and created renewed interest in studying other co-signaling receptors, which until recently have not been as well studied. In addition to co-inhibitory receptors, co-stimulatory receptors like OX40, GITR and 4-1BB have also been widely implicated in immune homeostasis and T-cell stimulation, and use of agonistic antibodies against OX40, GITR and 4-1BB has been effective in causing tumor regression. Although ICB has seen unprecedented success in cancer treatment, autoimmune adverse events arising from ICB due to loss of Treg homeostasis poses a major obstacle. Herein, we comprehensively review the role of various co-stimulatory and co-inhibitory receptors in Treg biology and immune homeostasis, autoimmunity, and anti-tumor immunity. Furthermore, we discuss the autoimmune adverse events arising upon targeting these co-signaling receptors to augment anti-tumor immune responses.