Therapeutically targeting the unique disease landscape of pediatric high-grade gliomas.

Pediatric high-grade gliomas (pHGG) are a rare yet devastating malignancy of the central nervous system's glial support cells, affecting children, adolescents, and young adults. Tumors of the central nervous system account for the leading cause of pediatric mortality of which high-grade gliomas present a significantly grim prognosis. While the past few decades have seen many pediatric cancers experiencing significant improvements in overall survival, the prospect of survival for patients diagnosed with pHGGs has conversely remained unchanged. This can be attributed in part to tumor heterogeneity and the existence of the blood-brain barrier. Advances in discovery research have substantiated the existence of unique subgroups of pHGGs displaying alternate responses to different therapeutics and varying degrees of overall survival. This highlights a necessity to approach discovery research and clinical management of the disease in an alternative subtype-dependent manner. This review covers traditional approaches to the therapeutic management of pHGGs, limitations of such methods and emerging alternatives. Novel mutations which predominate the pHGG landscape are highlighted and the therapeutic potential of targeting them in a subtype specific manner discussed. Collectively, this provides an insight into issues in need of transformative progress which arise during the management of pHGGs.

Phase I/IIa Trial in Advanced Pancreatic Ductal Adenocarcinoma Treated with Cytotoxic Drug-Packaged, EGFR-Targeted Nanocells and Glycolipid-Packaged Nanocells.

PURPOSE: We assessed the safety and efficacy of an EGFR-targeted, super-cytotoxic drug, PNU-159682-packaged nanocells with α-galactosyl ceramide-packaged nanocells (E-EDV-D682/GC) in patients with advanced pancreatic ductal adenocarcinoma (PDAC) who had exhausted all treatment options. PATIENTS AND METHODS: ENG9 was a first-in-man, single-arm, open-label, phase I/IIa, dose-escalation clinical trial. Eligible patients had advanced PDAC, Eastern Cooperative Oncology Group status 0 to 1, and failed all treatments. Primary endpoints were safety and overall survival (OS). RESULTS: Of 25 enrolled patients, seven were withdrawn due to rapidly progressive disease and one patient withdrew consent. All 25 patients were assessed for toxicity, 24 patients were assessed for OS, which was also assessed for 17 patients completing one treatment cycle [evaluable subset (ES)]. Nineteen patients (76.0%) experienced at least one treatment-related adverse event (graded 1 to 2) resolving within hours. There were no safety concerns, dose reductions, patient withdrawal, or treatment-related deaths.Median OS (mOS) was 4.4 months; however, mOS of the 17 ES patients was 6.9 months [208 days; range, 83-591 days; 95.0% confidence interval (CI), 5.6-10.3 months] and mOS of seven patients who did not complete one cycle was 1.8 months (54 days; range, 21-72; 95.0% CI, 1.2-2.2 months). Of the ES, 47.1% achieved stable disease and one partial response. Ten subjects in the ES survived over 6 months, the longest 19.7 months. During treatments, 82.0% of the ES maintained stable weight. CONCLUSIONS: E-EDV-D682/GC provided significant OS, minimal side effects, and weight stabilization in patients with advanced PDAC. Advanced PDAC can be safely treated with super-cytotoxic drugs via EnGeneIC Dream Vectors to overcome multidrug resistance.

Integrin-linked kinase expression in myeloid cells promotes colon tumorigenesis.

Colorectal cancer (CRC) is one of the most common forms of cancer worldwide and treatment options for advanced CRC, which has a low 5-year survival rate, remain limited. Integrin-linked kinase (ILK), a multifunctional, scaffolding, pseudo-kinase regulating many integrin-mediated cellular processes, is highly expressed in many cancers. However, the role of ILK in cancer progression is yet to be fully understood. We have previously uncovered a pro-inflammatory role for myeloid-specific ILK in dextran sodium sulfate (DSS)-induced colitis. To establish a correlation between chronic intestinal inflammation and colorectal cancer (CRC), we investigated the role of myeloid-ILK in mouse models of CRC. When myeloid-ILK deficient mice along with the WT control mice were subjected to colitis-associated and APCmin/+-driven CRC, tumour burden was reduced by myeloid-ILK deficiency in both models. The tumour-promoting phenotype of macrophages, M2 polarization, in vitro was impaired by the ILK deficiency and the number of M2-specific marker CD206-expressing tumour-associated macrophages (TAMs) in vivo were significantly diminished in myeloid-ILK deficient mice. Myeloid-ILK deficient mice showed enhanced tumour infiltration of CD8+ T cells and reduced tumour infiltration of FOXP3+ T cells in colitis-associated and APCmin/+-driven CRC, respectively, with an overall elevated CD8+/FOXP3+ ratio suggesting an anti-tumour immune phenotypes. In patient CRC tissue microarrays we observed elevated ILK+ myeloid (ILK+ CD11b+) cells in tumour sections compared to adjacent normal tissues, suggesting a conserved role for myeloid-ILK in CRC development in both human and animal models. This study identifies myeloid-specific ILK expression as novel driver of CRC, which could be targeted as a potential therapeutic option for advanced disease.

Genistein Targets STING-Driven Antiviral Responses.

Cytoplasmic detection of DNA by cyclic GMP-AMP (cGAMP) synthase (cGAS) is an essential component of antiviral responses. Upon synthesis, cGAMP binds to the stimulator of interferon (IFN) genes (STING) in infected and adjacent cells through intercellular transfer by connexins forming gap-junctions, eliciting a strong IFN-ß-driven antiviral response. We demonstrate here that Genistein, a flavonoid compound naturally occurring in soy-based foods, inhibits cGAS-STING antiviral signaling at two levels. First, Genistein pretreatment of cGAMP-producing cells inhibited gap-junction intercellular communication, resulting in reduced STING responses in adjacent cells. In addition, Genistein directly blocked STING activation by the murine agonist DMXAA, by decreasing the interaction of STING with TBK1 and IKKε. As a result, Genistein attenuated STING signaling in human and mouse cells, dampening antiviral activity against Semliki Forest Virus infection. Collectively, our findings identify a previously unrecognized proviral activity of Genistein mediated via its inhibitory effects at two levels of cGAS-STING signaling. IMPORTANCE Several reports suggest that Genistein exhibits antiviral activities against DNA viruses. Our work uncovers a previously unrecognized proviral effect of Genistein, through inhibition of the cGAS-STING pathway at the level of cGAMP transfer and its sensing by STING. This suggests that the use of Genistein as an antiviral should be taken with caution as it may reduce the protective antiviral effects elicited by host STING activation.

Integrin-Linked Kinase Expression Characterizes the Immunosuppressive Tumor Microenvironment in Colorectal Cancer and Regulates PD-L1 Expression and Immune Cell Cytotoxicity.

Integrin-linked kinase (ILK) has been implicated as a molecular driver and mediator in both inflammation and tumorigenesis of the colon. However, a role for ILK in the tumor microenvironment (TME) and immune evasion has not been investigated. Here, we show a correlation of ILK expression with the immunosuppressive TME and cancer prognosis. We also uncover a role for ILK in the regulation of programmed death-ligand 1 (PD-L1) expression and immune cell cytotoxicity. Interrogation of web-based data-mining platforms, showed upregulation of ILK expression in tumors and adjacent-non tumor tissue of colorectal cancer (CRC) associated with poor survival and advanced stages. ILK expression was correlated with cancer-associated fibroblast (CAFs) and immunosuppressive cell infiltration including regulatory T cells (Treg) and M2 macrophages (M2) in addition to their gene markers. ILK expression was also significantly correlated with the expression of different cytokines and chemokines. ILK expression showed pronounced association with different important immune checkpoints including PD-L1. Deletion of the ILK gene in PD-L1 positive CRC cell lines using a doxycycline inducible-CRISPR/Cas9, resulted in suppression of both the basal and IFNγ-induced PD-L1 expression via downregulating NF-κB p65. This subsequently sensitized the CRC cells to NK92 immune cell cytotoxicity. These findings suggest that ILK can be used as a biomarker for prognosis and immune cell infiltration in colon cancer. Moreover, ILK could provide a therapeutic target to prevent immune evasion mediated by the expression of PD-L1.

Nanocell COVID-19 vaccine triggers a novel immune response pathway producing high-affinity antibodies which neutralize all variants of concern.

Most current anti-viral vaccines elicit a humoral and cellular immune response via the pathway of phagocytic cell mediated viral antigen presentation to B and T cell surface receptors. However, this pathway results in reduced ability to neutralize S-protein Receptor Binding Domains (RBDs) from several Variants of Concern (VOC) and the rapid waning of memory B cell response requiring vaccine reformulation to cover dominant VOC S-proteins and multiple boosters. Here we show for the first time in mice and humans, that a bacterially derived, non-living, nanocell (EDV; EnGeneIC Dream Vector) packaged with plasmid expressed SARS-CoV-2 S-protein and α-galactosyl ceramide adjuvant (EDV-COVID-αGC), stimulates an alternate pathway due to dendritic cells (DC) displaying both S-polypeptides and αGC thereby recruiting and activating iNKT cells with release of IFNγ. This triggers DC activation/maturation, activation of follicular helper T cells (TFH), cognate help to B cells with secretion of a cytokine milieu promoting B cell maturation, somatic hypermutation in germinal centers to result in high affinity antibodies. Surrogate virus neutralization tests show 90-100% neutralization of ancestral and early VOC in mice and human trial volunteers. EDV-COVID-αGC as a third dose booster neutralized Omicron BA. 4/5. Serum and PBMC analyses reveal long lasting S-specific memory B and T cells. In contrast, control EDVs lacking αGC, did not engage the iNKT/DC pathway resulting in antibody responses unable to neutralize all VOCs and had a reduced B cell memory. The vaccine is lyophilized, stored and transported at room temperature with a shelf-life of over a year.

A Potential Role for Integrin-Linked Kinase in Colorectal Cancer Growth and Progression via Regulating Senescence and Immunity.

Integrin-linked kinase (ILK) has been implicated as a molecular driver and mediator in both inflammation and tumorigenesis of the colon. ILK functions as an adaptor and mediator protein linking the extracellular matrix with downstream signaling pathways. ILK is broadly expressed in many human tissues and cells. It is also overexpressed in many cancers, including colorectal cancer (CRC). Inflammation, as evidenced by inflammatory bowel disease (IBD), is one of the highest risk factors for initiating CRC. This has led to the hypothesis that targeting ILK therapeutically could have potential in CRC, as it regulates different cellular processes associated with CRC development and progression as well as inflammation in the colon. A number of studies have indicated an ILK function in senescence, a cellular process that arrests the cell cycle while maintaining active metabolism and transcription. Senescent cells produce different secretions collectively known as the senescence-associated secretory phenotype (SASP). The SASP secretions influence infiltration of different immune cells, either positively for clearing senescent cells or negatively for promoting tumor growth, reflecting the dual role of senescence in cancer. However, a role for ILK in senescence and immunity in CRC remains to be determined. In this review, we discuss the possible role for ILK in senescence and immunity, paying particular attention to the relevance of ILK in CRC. We also examine how activating Toll-like receptors (TLRs) and their agonists in CRC could trigger immune responses against cancer, as a combination therapy with ILK inhibition.

Mitochondrial arginase-2 is essential for IL-10 metabolic reprogramming of inflammatory macrophages.

Mitochondria are important regulators of macrophage polarisation. Here, we show that arginase-2 (Arg2) is a microRNA-155 (miR-155) and interleukin-10 (IL-10) regulated protein localized at the mitochondria in inflammatory macrophages, and is critical for IL-10-induced modulation of mitochondrial dynamics and oxidative respiration. Mechanistically, the catalytic activity and presence of Arg2 at the mitochondria is crucial for oxidative phosphorylation. We further show that Arg2 mediates this process by increasing the activity of complex II (succinate dehydrogenase). Moreover, Arg2 is essential for IL-10-mediated downregulation of the inflammatory mediators succinate, hypoxia inducible factor 1α (HIF-1α) and IL-1ß in vitro. Accordingly, HIF-1α and IL-1ß are highly expressed in an LPS-induced in vivo model of acute inflammation using Arg2-/- mice. These findings shed light on a new arm of IL-10-mediated metabolic regulation, working to resolve the inflammatory status of the cell.

Connexin-Dependent Transfer of cGAMP to Phagocytes Modulates Antiviral Responses.

Activation of cyclic GMP-AMP (cGAMP) synthase (cGAS) plays a critical role in antiviral responses to many DNA viruses. Sensing of cytosolic DNA by cGAS results in synthesis of the endogenous second messenger cGAMP that activates stimulator of interferon genes (STING) in infected cells. Critically, cGAMP can also propagate antiviral responses to uninfected cells through intercellular transfer, although the modalities of this transfer between epithelial and immune cells remain poorly defined. We demonstrate here that cGAMP-producing epithelial cells can transactivate STING in cocultured macrophages through direct cGAMP transfer. cGAMP transfer was reliant upon connexin expression by epithelial cells and pharmacological inhibition of connexins blunted STING-dependent transactivation of the macrophage compartment. Macrophage transactivation by cGAMP contributed to a positive-feedback loop amplifying antiviral responses, significantly protecting uninfected epithelial cells against viral infection. Collectively, our findings constitute the first direct evidence of a connexin-dependent cGAMP transfer to macrophages by epithelial cells, to amplify antiviral responses.IMPORTANCE Recent studies suggest that extracellular cGAMP can be taken up by macrophages to engage STING through several mechanisms. Our work demonstrates that connexin-dependent communication between epithelial cells and macrophages plays a significant role in the amplification of antiviral responses mediated by cGAMP and suggests that pharmacological strategies aimed at modulating connexins may have therapeutic applications to control antiviral responses in humans.

Mechanisms and consequences of constitutive activation of integrin-linked kinase in acute myeloid leukemia.

Integrin-linked kinase (ILK) has emerged as a critical adaptor and mediator protein in cell signaling pathways that is commonly deregulated in acute myeloid leukemia (AML). This has led to the expectation that therapeutic targeting of ILK may be a useful option in treating leukemia. Although ILK can regulate many cellular processes, including cell differentiation, survival, migration, apoptosis and production of pro-inflammatory cytokines, its role in promoting AML is still unclear. However, its ability to mediate phosphorylation and regulate the important hematopoietic stem cell regulators protein kinase B (AKT) and glycogen synthase kinase-3ß supports ILK as an attractive target for the development of novel anticancer therapeutics. In this review, we summarize the existing knowledge of ILK signaling and its impact on cytokines, paying particular attention to the relevance of ILK signaling in AML. We also discuss the rationale for targeting ILK in the treatment of AML and conclude with perspectives on the future of ILK-targeted therapy in AML.

PD-L1 expression is a prognostic factor in subgroups of gastric cancer patients stratified according to their levels of CD8 and FOXP3 immune markers.

Current studies aiming at identifying single immune markers with prognostic value have limitations in the context of complex antitumor immunity and cancer immune evasion. Here, we show how the integration of several immune markers influences the predictions of prognosis of gastric cancer (GC) patients. We analyzed Tissue Microarray (TMA) by multiplex immunohistochemistry and measured the expression of immune checkpoint molecule PD-L1 together with antitumor CD8 T cells and immune suppressive FOXP3 Treg cells in a cohort of GC patients. Unsupervised hierarchical clustering analysis of these markers was used to define correlations between CD8 T, FOXP3 Treg and PD-L1 cell densities. We found that FOXP3 and PD-L1 densities were elevated while CD8 T cells were decreased in tumor tissues compared to their adjacent normal tissues. However, patient stratification based on each one of these markers individually did not show significant prognostic value on patient survival. Conversely, combination of the ratios of CD8/FOXP3 and CD8/PD-L1 enabled the identification of patient subgroups with different survival outcomes. As such, high densities of PD-L1 in patients with high CD8/FOXP3 and low CD8/PD-L1 ratios correlated with increased survival. Collectively, this work demonstrates the need for the integration of several immune markers to obtain more meaningful survival prognosis and patient stratification. In addition, our work provides insights into the complex tumor immune evasion and immune regulation by the tumor-infiltrating effector and suppressor cells, informing on the best use of immunotherapy options for treating patients.

Meeting summary: 2nd Aegean Conference on Cytokine Signaling in Cancer.

Cytokines and chemokines are intricately connected to cancer initiation, progression and metastasis as well as to innate and adaptive host defense mechanisms against transformed cells. The Aegean Conference on Cytokine Signaling in Cancer (ACCSC) aims to bring together researchers in this highly targeted area of cancer research in a lovely and relaxing Greek-Mediterranean backdrop to discuss latest developments. Being small in size with about one hundred participants, this conference fosters scientific and social interactions among established and emerging scientists in clinical and basic research in diverse fields of oncology, biochemistry, biophysics, genetics and immunology. The 2nd ACCSC held at Heraklion on the Greek island of Crete was organized by Serge Fuchs (University of Pennsylvania), Mathias Muller (University of Veterinary Medicine Vienna), Leonidas Platanias (Northwestern University, Chicago) and Belinda Parker (La Trobe University, Melbourne) between May 30 and June 04, 2017, was a great success in every single aspect of a high level scientific meeting. Signaling within cancer cells as well as in stromal and immune cells is the common thread of this conference series. An outline of the research topics discussed at this conference is presented here to emphasize its high quality and to stimulate interest among cytokine researchers to participate in future ACCSC meetings.

Identification of a histone family gene signature for predicting the prognosis of cervical cancer patients.

Heterogeneity in terms of tumor characteristics, prognosis, and survival among cancer patients is an unsolved issue. Here, we systematically analyzed the aberrant expression patterns of cervical cancer using RNA-Seq data from The Cancer Genome Atlas (TCGA). We incorporated gene profiling, molecular signatures, functional and pathway information with gene set enrichment and protein-protein interaction (PPI) network analysis, to identify sub-networks of genes. Those identified genes relating to DNA replication and DNA repair-mediated signaling pathways associated with systemic lupus erythematosus (SLE). Next, we combined cross-validated prognostic scores to build an integrated prognostic model for survival prediction. The combined approach revealed that the DNA repair-mediated including the functional interaction module of 18 histone genes (Histone cluster 1 H2A, B and H4), were significantly correlated with the survival rate. Furthermore, five of these histone genes were highly expressed in three cervical cancer cohorts from the Oncomine database. Comparison of high and low histone variant-expressing human cervical cancer cell lines revealed different responses to DNA damage, suggesting protective functions of histone genes against DNA damage. Collectively, we provide evidence that two SLE-associated gene sets (HIST1H2BD and HIST1H2BJ; and HIST1H2BD, HIST1H2BJ, HIST1H2BH, HIST1H2AM and HIST1H4K) can be used as prognostic factors for survival prediction among cervical cancer patients.

Topoisomerase 1 Inhibition Promotes Cyclic GMP-AMP Synthase-Dependent Antiviral Responses.

Inflammatory responses, while essential for pathogen clearance, can also be deleterious to the host. Chemical inhibition of topoisomerase 1 (Top1) by low-dose camptothecin (CPT) can suppress transcriptional induction of antiviral and inflammatory genes and protect animals from excessive and damaging inflammatory responses. We describe the unexpected finding that minor DNA damage from topoisomerase 1 inhibition with low-dose CPT can trigger a strong antiviral immune response through cyclic GMP-AMP synthase (cGAS) detection of cytoplasmic DNA. This argues against CPT having only anti-inflammatory activity. Furthermore, expression of the simian virus 40 (SV40) large T antigen was paramount to the proinflammatory antiviral activity of CPT, as it potentiated cytoplasmic DNA leakage and subsequent cGAS recruitment in human and mouse cell lines. This work suggests that the capacity of Top1 inhibitors to blunt inflammatory responses can be counteracted by viral oncogenes and that this should be taken into account for their therapeutic development.IMPORTANCE Recent studies suggest that low-dose DNA-damaging compounds traditionally used in cancer therapy can have opposite effects on antiviral responses, either suppressing (with the example of CPT) or potentiating (with the example of doxorubicin) them. Our work demonstrates that the minor DNA damage promoted by low-dose CPT can also trigger strong antiviral responses, dependent on the presence of viral oncogenes. Taken together, these results call for caution in the therapeutic use of low-dose chemotherapy agents to modulate antiviral responses in humans.

Understanding immune phenotypes in human gastric disease tissues by multiplexed immunohistochemistry.

BACKGROUND: Understanding immune phenotypes and human gastric disease in situ requires an approach that leverages multiplexed immunohistochemistry (mIHC) with multispectral imaging to facilitate precise image analyses. METHODS: We developed a novel 4-color mIHC assay based on tyramide signal amplification that allowed us to reliably interrogate immunologic checkpoints, including programmed death-ligand 1 (PD-L1), cytotoxic T cells (CD8+T) and regulatory T cells (Foxp3), in formalin-fixed, paraffin-embedded tissues of various human gastric diseases. By observing cell phenotypes within the disease tissue microenvironment, we were able to determine specific co-localized staining combinations and various measures of cell density. RESULTS: We found that PD-L1 was expressed in gastric ulcer and in tumor cells (TCs), as well as in tumor-infiltrating immune cells (TIICs), but not in normal gastric mucosa or other gastric intraepithelial neoplastic tissues. Furthermore, we found no significant reduction in CD8+T cells, whereas the ratio of CD8+T:Foxp3 cells and CD8+T:PD-L1 cells was suppressed in tumor tissues and elevated in adjacent normal tissues. An unsupervised hierarchical analysis also identified correlations between CD8+T and Foxp3+ tumor-infiltrating lymphocyte (TIL) densities and average PD-L1 levels. Three main groups were identified based on the results of CD8+T:PD-L1 ratios in gastric tumor tissues. Furthermore, integrating CD8+T:Foxp3 ratios, which increased the complexity for immune phenotype status, revealed 6-7 clusters that enabled the separation of gastric cancer patients at the same clinical stage into different risk-group subsets. CONCLUSIONS: Characterizing immune phenotypes in human gastric disease tissues via multiplexed immunohistochemistry may help guide PD-L1 clinical therapy. Observing unique disease tissue microenvironments can improve our understanding of immune phenotypes and cell interactions within these microenvironments, providing the ability to predict safe responses to immunotherapies.

An Emergence Framework of Carcinogenesis.

Experimental paradigms provide the framework for the understanding of cancer, and drive research and treatment, but are rarely considered by clinicians. The somatic mutation theory (SMT), in which cancer is considered a genetic disease, has been the predominant traditional model of cancer for over 50 years. More recently, alternative theories have been proposed, such as tissue organization field theory (TOFT), evolutionary models, and inflammatory models. Key concepts within the various models have led to them being difficult to reconcile. Progressively, it has been recognized that biological systems cannot be fully explained by the physicochemical properties of their constituent parts. There is an increasing call for a 'systems' approach. Incorporating the concepts of 'emergence', 'systems', 'thermodynamics', and 'chaos', a single integrated framework for carcinogenesis has been developed, enabling existing theories to become compatible as alternative mechanisms, facilitating the integration of bioinformatics and providing a structure in which translational research can flow from both 'benchtop to bedside' and 'bedside to benchtop'. In this review, a basic understanding of the key concepts of 'emergence', 'systems', 'system levels', 'complexity', 'thermodynamics', 'entropy', 'chaos', and 'fractals' is provided. Non-linear mathematical equations are included where possible to demonstrate compatibility with bioinformatics. Twelve principles that define the 'emergence framework of carcinogenesis' are developed, with principles 1-10 encapsulating the key concepts upon which the framework is built and their application to carcinogenesis. Principle 11 relates the framework to cancer progression. Principle 12 relates to the application of the framework to translational research. The 'emergence framework of carcinogenesis' collates current paradigms, concepts, and evidence around carcinogenesis into a single framework that incorporates previously incompatible viewpoints and ideas. Any researcher, scientist, or clinician involved in research, treatment, or prevention of cancer can employ this framework.

Integrin-Linked Kinase Expression in Myeloid Cells Promotes Inflammatory Signaling during Experimental Colitis.

The pathology of inflammatory bowel diseases is driven by the inflammatory signaling pathways associated with mucosal epithelial damage. Myeloid cells are known to play an essential role in mediating epithelial inflammatory responses during injury. However, the precise role of these cells in stimulating intestinal inflammation and the subsequent tissue damage is unclear. In this article, we show that expression of integrin-linked kinase (ILK) in myeloid cells is critical for the epithelial inflammatory signaling during colitis induced by dextran sodium sulfate. Myeloid ILK (M-ILK) deficiency significantly ameliorates the pathology of experimental colitis. In response to dextran sodium sulfate, colonic infiltration of neutrophils and inflammatory cytokine production are impaired in M-ILK-deficient mice, and activation of epithelial NF-κB and PI3K signaling pathways are restricted by the M-ILK deficiency. In contrast, reduced epithelial damage in M-ILK-deficient mice is correlated with elevated levels of epithelial Stat3 activation and proliferation. Moreover, M-ILK-dependent inflammatory signaling in the mucosal epithelium can be therapeutically targeted by the pharmacological inhibition of ILK during experimental colitis. Collectively, these findings identify M-ILK as a critical regulator of epithelial inflammatory signaling pathways during colitis and, as a consequence, targeting M-ILK could provide therapeutic benefit.

ATF3 Repression of BCL-XL Determines Apoptotic Sensitivity to HDAC Inhibitors across Tumor Types.

Purpose: Histone deacetylase inhibitors (HDACi) are epigenome-targeting small molecules approved for the treatment of cutaneous T-cell lymphoma and multiple myeloma. They have also demonstrated clinical activity in acute myelogenous leukemia, non-small cell lung cancer, and estrogen receptor-positive breast cancer, and trials are underway assessing their activity in combination regimens including immunotherapy. However, there is currently no clear strategy to reliably predict HDACi sensitivity. In colon cancer cells, apoptotic sensitivity to HDACi is associated with transcriptional induction of multiple immediate-early (IE) genes. Here, we examined whether this transcriptional response predicts HDACi sensitivity across tumor type and investigated the mechanism by which it triggers apoptosis.Experimental Design: Fifty cancer cell lines from diverse tumor types were screened to establish the correlation between apoptotic sensitivity, induction of IE genes, and components of the intrinsic apoptotic pathway.Results: We show that sensitivity to HDACi across tumor types is predicted by induction of the IE genes FOS, JUN, and ATF3, but that only ATF3 is required for HDACi-induced apoptosis. We further demonstrate that the proapoptotic function of ATF3 is mediated through direct transcriptional repression of the prosurvival factor BCL-XL (BCL2L1) These findings provided the rationale for dual inhibition of HDAC and BCL-XL, which we show strongly cooperate to overcome inherent resistance to HDACi across diverse tumor cell types.Conclusions: These findings explain the heterogeneous responses of tumor cells to HDACi-induced apoptosis and suggest a framework for predicting response and expanding their therapeutic use in multiple cancer types. Clin Cancer Res; 23(18); 5573-84. ©2017 AACR.