IRF-8 controls melanoma progression by regulating the cross talk between cancer and immune cells within the tumor microenvironment

IRF8 Regulates Intrinsic Ferroptosis through Repressing p53 Expression to Maintain Tumor Cell Sensitivity to Cytotoxic T Lymphocytes

Ferroptosis has emerged as a cytotoxic T lymphocyte (CTL)-induced tumor cell death pathway. The regulation of tumor cell sensitivity to ferroptosis is incompletely understood. Here, we report that interferon regulatory factor 8 (IRF8) functions as a regulator of tumor cell intrinsic ferroptosis. Genome-wide gene expression profiling identified the ferroptosis pathway as an IRF8-regulated pathway in tumor cells. IRF8.KO tumor cells acquire resistance to intrinsic ferroptosis induction and IRF8-deficient tumor cells also exhibit decreased ferroptosis in response to tumor-specific CTLs. Irf8 deletion increased p53 expression in tumor cells and knocking out p53 in IRF8.KO tumor cells restored tumor cell sensitivity to intrinsic ferroptosis induction. Furthermore, IRF8.KO tumor cells grew significantly faster than WT tumor cells in immune-competent mice. To restore IRF8 expression in tumor cells, we designed and synthesized codon usage-optimized IRF8-encoding DNA to generate IRF8-encoding plasmid NTC9385R-mIRF8. Restoring IRF8 expression via a lipid nanoparticle-encapsulated NTC9385R-mIRF8 plasmid therapy suppressed established tumor growth in vivo. In human cancer patients, nivolumab responders have a significantly higher IRF8 expression level in their tumor cells as compared to the non-responders. Our data determine that IRF8 represses p53 expression to maintain tumor cell sensitivity to intrinsic ferroptosis.

NEUROD1 predicts better prognosis in pancreatic cancer revealed by a TILs-based prognostic signature

It has been well-defined that tumor-infiltrating lymphocytes (TILs) play critical roles in pancreatic cancer (PaCa) progression. This research aimed to comprehensively explore the composition of TILs in PaCa and their potential clinical significance. A total of 178 samples from the TCGA and 63 samples from the GSE57495 dataset were enrolled in our study. ImmuCellAI was applied to calculate the infiltrating abundance of 24 immune cell types in PaCa and further survival analysis revealed the prognostic values of TILs in PaCa. Moreover, the Hallmark enticement analysis of differentially expressed genes (DEGs) between low- and high-risk groups was performed as well. Immunohistochemistry staining was used to evaluate NEUROD1 expression. As result, different kinds of TILs had distinct infiltrating features. In addition, Specific TILs subsets had notable prognostic values in PaCa. We further established a 6-TILs signature to assess the prognosis of PaCa patients. Kaplan-Meier and Cox regression analyses both suggested the significant prognostic value of the signature in PaCa. Based on the prognostic signature, we screened a great deal of potential prognostic biomarkers and successfully validated NEUROD1 as a novel prognostic biomarker in PaCa. Overall, the current study illuminated the immune cells infiltrating the landscape in PaCa and identified a TILs-dependent signature and NEUROD1 for prognostic prediction in PaCa patients.

IRF8: Mechanism of Action and Health Implications

Interferon regulatory factor 8 (IRF8) is a transcription factor of the IRF protein family. IRF8 was originally identified as an essentialfactor for myeloid cell lineage commitment and differentiation. Deletion of Irf8 leads to massive accumulation of CD11b+Gr1+ immature myeloid cells (IMCs), particularly the CD11b+Ly6Chi/+Ly6G- polymorphonuclear myeloid-derived suppressor cell-like cells (PMN-MDSCs). Under pathological conditions such as cancer, Irf8 is silenced by its promoter DNA hypermethylation, resulting in accumulation of PMN-MDSCs and CD11b+ Ly6G+Ly6Clo monocytic MDSCs (M-MDSCs) in mice. IRF8 is often silenced in MDSCs in human cancer patients. MDSCs are heterogeneous populations of immune suppressive cells that suppress T and NK cell activity to promote tumor immune evasion and produce growth factors to exert direct tumor-promoting activity. Emerging experimental data reveals that IRF8 is also expressed in non-hematopoietic cells. Epithelial cell-expressed IRF8 regulates apoptosis and represses Osteopontin (OPN). Human tumor cells may use the IRF8 promoter DNA methylation as a mechanism to repress IRF8 expression to advance cancer through acquiring apoptosis resistance and OPN up-regulation. Elevated OPN engages CD44 to suppress T cell activation and promote tumor cell stemness to advance cancer. IRF8 thus is a transcription factor that regulates both the immune and non-immune components in human health and diseases.

Immunotherapy discovery on tumor organoid-on-a-chip platforms that recapitulate the tumor microenvironment

Cancer immunotherapy has achieved remarkable success over the past decade by modulating patients' own immune systems and unleashing pre-existing immunity. However, only a minority of cancer patients across different cancer types are able to benefit from immunotherapy treatment; moreover, among those small portions of patients with response, intrinsic and acquired resistance remains a persistent challenge. Because the tumor microenvironment (TME) is well recognized to play a critical role in tumor initiation, progression, metastasis, and the suppression of the immune system and responses to immunotherapy, understanding the interactions between the TME and the immune system is a pivotal step in developing novel and efficient cancer immunotherapies. With unique features such as low reagent consumption, dynamic and precise fluid control, versatile structures and function designs, and 3D cell co-culture, microfluidic tumor organoid-on-a-chip platforms that recapitulate key factors of the TME and the immune contexture have emerged as innovative reliable tools to investigate how tumors regulate their TME to counteract antitumor immunity and the mechanism of tumor resistance to immunotherapy. In this comprehensive review, we focus on recent advances in tumor organoid-on-a-chip platforms for studying the interaction between the TME and the immune system. We first review different factors of the TME that recent microfluidic in vitro systems reproduce to generate advanced tools to imitate the crosstalk between the TME and the immune system. Then, we discuss their applications in the assessment of different immunotherapies' efficacy using tumor organoid-on-a-chip platforms. Finally, we present an overview and the outlook of engineered microfluidic platforms in investigating the interactions between cancer and immune systems, and the adoption of patient-on-a-chip models in clinical applications toward personalized immunotherapy.

Bona Fide Tumor Suppressor Genes Hypermethylated in Melanoma: A Narrative Review

Loss-of-function events in tumor suppressor genes (TSGs) contribute to the development and progression of cutaneous malignant melanoma (CMM). Epigenetic alterations are the major mechanisms of TSG inactivation, in particular, silencing by promoter CpG-island hypermethylation. TSGs are valuable tools in diagnosis and prognosis and, possibly, in future targeted therapy. The aim of this narrative review is to outline bona fide TSGs affected by promoter CpG-island hypermethylation and their functional role in the progression of CMM. We conducted a systematic literature review to identify studies providing evidence of bona fide TSGs by cell line or animal experiments. We performed a broad first search and a gene-specific second search, supplemented by reference checking. We included studies describing bona fide TSGs in CMM with promoter CpG-island hypermethylation in which inactivating mechanisms were reported. We extracted data about protein role, pathway, experiments conducted to meet the bona fide criteria and hallmarks of cancer acquired by TSG inactivation. A total of 24 studies were included, describing 24 bona fide TSGs silenced by promoter CpG-island hypermethylation in CMM. Their effect on cell proliferation, apoptosis, growth, senescence, angiogenesis, migration, invasion or metastasis is also described. These data give further insight into the role of TSGs in the progression of CMM.

Single cell RNA sequencing of AML initiating cells reveals RNA-based evolution during disease progression

The prognosis of most patients with AML is poor due to frequent disease relapse. The cause of relapse is thought to be from the persistence of leukemia initiating cells (LIC's) following treatment. Here we assessed RNA based changes in LICs from matched patient diagnosis and relapse samples using single-cell RNA sequencing. Previous studies on AML progression have focused on genetic changes at the DNA mutation level mostly in bulk AML cells and demonstrated the existence of DNA clonal evolution. Here we identified in LICs that the phenomenon of RNA clonal evolution occurs during AML progression. Despite the presence of vast transcriptional heterogeneity at the single cell level, pathway analysis identified common signaling networks involving metabolism, apoptosis and chemokine signaling that evolved during AML progression and become a signature of relapse samples. A subset of this gene signature was validated at the protein level in LICs by flow cytometry from an independent AML cohort and functional studies were performed to demonstrate co-targeting BCL2 and CXCR4 signaling may help overcome therapeutic challenges with AML heterogeneity. It is hoped this work will facilitate a greater understanding of AML relapse leading to improved prognostic biomarkers and therapeutic strategies to target LIC's.

Oncoimmunology Meets Organs-on-Chip

Oncoimmunology represents a biomedical research discipline coined to study the roles of immune system in cancer progression with the aim of discovering novel strategies to arm it against the malignancy. Infiltration of immune cells within the tumor microenvironment is an early event that results in the establishment of a dynamic cross-talk. Here, immune cells sense antigenic cues to mount a specific anti-tumor response while cancer cells emanate inhibitory signals to dampen it. Animals models have led to giant steps in this research context, and several tools to investigate the effect of immune infiltration in the tumor microenvironment are currently available. However, the use of animals represents a challenge due to ethical issues and long duration of experiments. Organs-on-chip are innovative tools not only to study how cells derived from different organs interact with each other, but also to investigate on the crosstalk between immune cells and different types of cancer cells. In this review, we describe the state-of-the-art of microfluidics and the impact of OOC in the field of oncoimmunology underlining the importance of this system in the advancements on the complexity of tumor microenvironment.

Intratumoral T-Lymphocyte Subsets in Canine Oral Melanoma and Their Association With Clinical and Histopathological Parameters

Canine oral melanoma is a common, aggressive tumor with limited treatment options. Tumor-infiltrating lymphocytes (TILs) are important in antitumor immunity. This study used histopathology and immunophenotyping by flow cytometry to evaluate the presence and distribution of TILs in canine oral melanoma, including the frequency of CD8⁺ T cells, CD4⁺ T cells, and regulatory T cells. Fifty samples of oral melanoma from 45 dogs that did not receive treatment prior to surgery were included in the study. The distribution of TILs in the tissue (brisk, nonbrisk, and absent) was evaluated in 48 samples. Twenty-eight (58%) samples had a brisk distribution pattern, 10 (21%) samples had a nonbrisk pattern, and 10 (21%) samples had an absent TIL pattern. Comparing the histological evaluation and the immunophenotyping data, it was observed that samples with a brisk TIL pattern had a higher frequency of CD8⁺ T lymphocytes (P = .05) and a lower frequency of CD4⁺/CD25⁺/FoxP3⁺ Tregs (P = .03), compared to the samples with nonbrisk and absent infiltrate patterns. Patients with a higher survival rate had higher TIL scores (P = .002), a brisk or nonbrisk TIL pattern (P = .001), and an increased frequency of CD8⁺ T lymphocytes infiltrating the tumor (P = .003). Our analysis suggests that the evaluation of TILs in canine oral melanoma is relevant to predict tumor aggressiveness and patient prognosis.

Construction of an immune-related gene signature for prediction of prognosis in patients with cervical cancer

Cervical cancer (CeCa) is becoming an intractable public health issue worldwide. Emerging evidence uncovers that the tumor progression and prognosis of patients with CeCa are tightly associated with the abundance of tumor-infiltrating immune cells. In the current study, the abundance of tumor-infiltrating immune cells in CeCa samples was assessed by using the ssGSEA, thereby generating two immune-related groups according to the immune status. A 4-gene prognostic signature (RIPOR2, DAAM2, SORBS1, and CXCL8) was next established based on the grouping and its predictive capability was validated by multiple analyses. The TIMER database was used to evaluate the association between 4 hub gene expression and immune cell infiltration. Immunophenoscore (IPS) was used to assess response to immune checkpoint inhibitors in CeCa samples. As the results, a novel grouping strategy based on immune cell infiltration was developed and validated. Based on the grouping, a 4-gene signature was identified to be an independent prognostic indicator for overall survival (OS) in CeCa patients. Among the 4 hub genes, RIPOR2 and CXCL8 expression were significantly correlated with immune cell infiltration. Besides, higher immune checkpoints expression and IPS scores were found in the 4-gene signature low-risk group, suggesting a more immunoactive status that tended to respond to immune checkpoint inhibitors. To sum up, a novel immune-related signature is established to predict CeCa patients' prognosis and also associated with response to immune checkpoint inhibitors, which might be a promising prognostic stratification strategy and innovate therapeutic management.

Concomitant DNA methylation and transcriptome signatures define epidermal responses to acute solar UV radiation

The simultaneous analysis of different regulatory levels of biological phenomena by means of multi-omics data integration has proven an invaluable tool in modern precision medicine, yet many processes ultimately paving the way towards disease manifestation remain elusive and have not been studied in this regard. Here we investigated the early molecular events following repetitive UV irradiation of in vivo healthy human skin in depth on transcriptomic and epigenetic level. Our results provide first hints towards an immediate acquisition of epigenetic memories related to aging and cancer and demonstrate significantly correlated epigenetic and transcriptomic responses to irradiation stress. The data allowed the precise prediction of inter-individual UV sensitivity, and molecular subtyping on the integrated post-irradiation multi-omics data established the existence of three latent molecular phototypes. Importantly, further analysis suggested a form of melanin-independent DNA damage protection in subjects with higher innate UV resilience. This work establishes a high-resolution molecular landscape of the acute epidermal UV response and demonstrates the potential of integrative analyses to untangle complex and heterogeneous biological responses.

Loss of a Negative Feedback Loop between IRF8 and AR Promotes Prostate Cancer Growth and Enzalutamide Resistance

In incurable castration-resistant prostate cancer (CRPC), resistance to the novel androgen receptor (AR) antagonist enzalutamide is driven mainly by AR overexpression. Here we report that the expression of interferon regulatory factor 8 (IRF8) is increased in primary prostate cancer but decreased in CRPC compared with normal prostate tissue. Decreased expression of IRF8 positively associated with CRPC progression and enzalutamide resistance. IRF8 interacted with AR and promoted its degradation via activation of the ubiquitin/proteasome systems. Epigenetic knockdown of IRF8 promoted AR-mediated prostate cancer progression and enzalutamide resistance in vitro and in vivo. Furthermore, IFNα increased expression of IRF8 and improved the efficacy of enzalutamide in CRPC by targeting the IRF8-AR axis. We also provide preliminary evidence for the efficacy of IFNα with hormonotherapy in a clinical study. Collectively, this study identifies IRF8 both as a tumor suppressor in prostate cancer pathogenesis and a potential alternative therapeutic option to overcome enzalutamide resistance. SIGNIFICANCE: These findings identify IRF8-mediated AR degradation as a mechanism of resistance to AR-targeted therapy, highlighting the therapeutic potential of IFNα in targeting IRF8-AR axis in CRPC. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/13/2927/F1.large.jpg.

Comprehensive Analysis of the Expression and Prognosis for GBPs in Head and neck squamous cell carcinoma

Guanylate binding proteins (GBPs) belongs to the interferons (IFNs) induced guanylate-binding protein family (Guanosine triphosphatases, GTPases) consisting of seven homologous members, termed GBP1 to GBP7. We used multidimensional survey ways to explore GBPs expression, regulation, mutations, immune infiltration and functional networks in head and neck squamous cell carcinoma (HNSCC) patient data based on various open databases. The study provides staggered evidence for the significance of GBPs in HNSCC and its potential role as a novel biomarker. Our results showed that over expressions of 7 GBPs members and multivariate analysis suggested that N-stage, high expressions of GBP1 and low expression of GBP6/7 were linked to shorter OS in HNSCC patients. In addition, B cells of immune infiltrates stimulant the prognosis and might have a medical prognostic significance linked to GBPs in HNSCC. We assume that GBPs play a synergistic role in the viral related HNSCC. Our results show that data mining efficiently reveals information about GBPs expression in HNSCC and more importance lays a foundation for further research on the role of GBPs in cancers.

Consensus guidelines for the definition, detection and interpretation of immunogenic cell death

Cells succumbing to stress via regulated cell death (RCD) can initiate an adaptive immune response associated with immunological memory, provided they display sufficient antigenicity and adjuvanticity. Moreover, multiple intracellular and microenvironmental features determine the propensity of RCD to drive adaptive immunity. Here, we provide an updated operational definition of immunogenic cell death (ICD), discuss the key factors that dictate the ability of dying cells to drive an adaptive immune response, summarize experimental assays that are currently available for the assessment of ICD in vitro and in vivo, and formulate guidelines for their interpretation.

Small molecules-Giant leaps for immuno-oncology

Immuno-oncology therapies are revolutionizing the oncology landscape with checkpoint blockade becoming the treatment backbone for many indications. While inspiring, much work remains to increase the number of cancer patients that can benefit from these treatments. Thus, a new era of immuno-oncology research has begun which is focused on identifying novel combination regimes that lead to improved response rates. This review highlights the significance of small molecules in this approach and illustrates the huge progress that has been made to date.

An immunoevasive strategy through clinically-relevant pan-cancer genomic and transcriptomic alterations of JAK-STAT signaling components

BACKGROUND

Since its discovery almost three decades ago, the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway has paved the road for understanding inflammatory and immunity processes related to a wide range of human pathologies including cancer. Several studies have demonstrated the importance of JAK-STAT pathway components in regulating tumor initiation and metastatic progression, yet, the extent of how genetic alterations influence patient outcome is far from being understood.

METHODS

Focusing on 133 genes involved in JAK-STAT signaling, we investigated genomic, transcriptomic and clinical profiles of over 18,000 patients representing 21 diverse cancer types. We identified a core set of 28 putative gain- or loss-of-function JAK-STAT genes that correlated with survival outcomes using Cox proportional hazards regression and Kaplan-Meier analyses. Differential expression analyses between high- and low-expressing patient groups were performed to evaluate the consequences of JAK-STAT misexpression.

RESULTS

We found that copy number alterations underpinning transcriptional dysregulation of JAK-STAT pathway genes differ within and between cancer types. Integrated analyses uniting genomic and transcriptomic datasets revealed a core set of JAK-STAT pathway genes that correlated with survival outcomes in brain, renal, lung and endometrial cancers. High JAK-STAT scores were associated with increased mortality rates in brain and renal cancers, but not in lung and endometrial cancers where hyperactive JAK-STAT signaling is a positive prognostic factor. Patients with aberrant JAK-STAT signaling demonstrated pan-cancer molecular features associated with misexpression of genes in other oncogenic pathways (Wnt, MAPK, TGF-β, PPAR and VEGF). Brain and renal tumors with hyperactive JAK-STAT signaling had increased regulatory T cell gene (Treg) expression. A combined model uniting JAK-STAT and Tregs allowed further delineation of risk groups where patients with high JAK-STAT and Treg scores consistently performed the worst.

CONCLUSION

Providing a pan-cancer perspective of clinically-relevant JAK-STAT alterations, this study could serve as a framework for future research investigating anti-tumor immunity using combination therapy involving JAK-STAT and immune checkpoint inhibitors.

Direct Inhibition of IRF-Dependent Transcriptional Regulatory Mechanisms Associated With Disease

Interferon regulatory factors (IRFs) are a family of homologous proteins that regulate the transcription of interferons (IFNs) and IFN-induced gene expression. As such they are important modulating proteins in the Toll-like receptor (TLR) and IFN signaling pathways, which are vital elements of the innate immune system. IRFs have a multi-domain structure, with the N-terminal part acting as a DNA binding domain (DBD) that recognizes a DNA-binding motif similar to the IFN-stimulated response element (ISRE). The C-terminal part contains the IRF-association domain (IAD), with which they can self-associate, bind to IRF family members or interact with other transcription factors. This complex formation is crucial for DNA binding and the commencing of target-gene expression. IRFs bind DNA and exert their activating potential as homo or heterodimers with other IRFs. Moreover, they can form complexes (e.g., with Signal transducers and activators of transcription, STATs) and collaborate with other co-acting transcription factors such as Nuclear factor-κB (NF-κB) and PU.1. In time, more of these IRF co-activating mechanisms have been discovered, which may play a key role in the pathogenesis of many diseases, such as acute and chronic inflammation, autoimmune diseases, and cancer. Detailed knowledge of IRFs structure and activating mechanisms predisposes IRFs as potential targets for inhibition in therapeutic strategies connected to numerous immune system-originated diseases. Until now only indirect IRF modulation has been studied in terms of antiviral response regulation and cancer treatment, using mainly antisense oligonucleotides and siRNA knockdown strategies. However, none of these approaches so far entered clinical trials. Moreover, no direct IRF-inhibitory strategies have been reported. In this review, we summarize current knowledge of the different IRF-mediated transcriptional regulatory mechanisms and how they reflect the diverse functions of IRFs in homeostasis and in TLR and IFN signaling. Moreover, we present IRFs as promising inhibitory targets and propose a novel direct IRF-modulating strategy employing a pipeline approach that combines comparative in silico docking to the IRF-DBD with in vitro validation of IRF inhibition. We hypothesize that our methodology will enable the efficient identification of IRF-specific and pan-IRF inhibitors that can be used for the treatment of IRF-dependent disorders and malignancies.

Ex Vivo Tumor-on-a-Chip Platforms to Study Intercellular Interactions within the Tumor Microenvironment

The emergence of immunotherapies and recent FDA approval of several of them makes them a promising therapeutic strategy for cancer. While these advancements underscore the potential of engaging the immune system to target tumors, this approach has so far been efficient only for certain cancers. Extending immunotherapy as a widely acceptable treatment for various cancers requires a deeper understanding of the interactions of tumor cells within the tumor microenvironment (TME). The immune cells are a key component of the TME, which also includes other stromal cells, soluble factors, and extracellular matrix-based cues. While in vivo studies function as a gold standard, tissue-engineered microphysiological tumor models can offer patient-specific insights into cancer-immune interactions. These platforms, which recapitulate cellular and non-cellular components of the TME, enable a systematic understanding of the contribution of each component toward disease progression in isolation and in concert. Microfluidic-based microphysiological platforms recreating these environments, also known as "tumor-on-a-chip," are increasingly being utilized to study the effect of various elements of TME on tumor development. Herein are reviewed advancements in tumor-on-a-chip technology that are developed and used to understand the interaction of tumor cells with other surrounding cells, including immune cells, in the TME.

TNFα mediated ceramide generation triggers cisplatin induced apoptosis in B16F10 melanoma in a PKCδ independent manner

Ceramide is one of the important cellular components involved in cancer regulation and exerts its pleiotropic role in the protective immune response without exhibiting any adverse effects during malignant neoplasm. Although, the PKCδ-ceramide axis in cancer cells has been an effective target in reduction of cancer, involvement of PKCδ in inducing nephrotoxicity have become a major questionnaire. In the present study, we have elucidated the mechanism by which cisplatin exploits the ceramide to render cancer cell apoptosis leading to the abrogation of malignancy in a PKCδ independent pathway with lesser toxicity. Our study revealed that cisplatin treatment in PKCδ silenced melanoma cells induces ceramide mediated apoptosis. Moreover, cisplatin induced upregulation of the transcription factor IRF1 leading to the induction of the transcriptional activity of the TNFα promoter was evident from the pharmacological inhibition and RNA interference studies. Increased cellular expression of TNFα resulted in an elevated ceramide generation by stimulating acid-sphingomyelinase and cPLA₂. Furthermore, reciprocity in the regulation of sphingosine kinase 1 (Sphk1) and sphingosine kinase 2 (Sphk2) during PKCδ independent ceramide generation was also observed during cisplatin treatment. PKCδ inhibited murine melanoma model showed reduction in nephrotoxicity along with tumor regression by ceramide generation. Altogether, the current study emphasized the unexplored signaling cascade of ceramide generation by cisplatin during PKCδ silenced condition, which is associated with increased TNFα generation. Our findings enlightened the detailed mechanistic insight of ceramide mediated signaling by chemotherapeutic drugs in cancer therapy exploring a new range of targets for cancer treatment strategies.

Levels of peripheral blood polymorphonuclear myeloid-derived suppressor cells and selected cytokines are potentially prognostic of disease progression for patients with non-small cell lung cancer

Polymorphonuclear-MDSC (PMN-MDSC) have emerged as an independent prognostic factor for survival in NSCLC. Similarly, cytokine profiles have been used to identify subgroups of NSCLC patients with different clinical outcomes. This prospective study investigated whether the percentage of circulating PMN-MDSC, in conjunction with the levels of plasma cytokines, was more informative of disease progression than the analysis of either factor alone. We analyzed the phenotypic and functional profile of peripheral blood T-cell subsets (CD3+, CD3+CD4+ and CD3+CD8+), neutrophils (CD66b+) and polymorphonuclear-MDSC (PMN-MDSC; CD66b+CD11b+CD15+CD14-) as well as the concentration of 14 plasma cytokines (IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12 p70, IL-17A, IL-27, IL-29, IL-31, and IL-33, TNF-α, IFN-γ) in 90 treatment-naïve NSCLC patients and 25 healthy donors (HD). In contrast to HD, NSCLC patients had a higher percentage of PMN-MDSC and neutrophils (P < 0.0001) but a lower percentage of CD3+, CD3+CD4+ and CD3+CD8+ cells. PMN-MDSC% negatively correlated with the levels of IL1-β, IL-2, IL-27 and IL-29. Two groups of patients were identified according to the percentage of circulating PMN-MDSC. Patients with low PMN-MDSC (≤ 8%) had a better OS (22.1 months [95% CI 4.3-739.7]) than patients with high PMN-MDSC (9.3 months [95% CI 0-18.8]). OS was significantly different among groups of patients stratified by both PMN-MDSC% and cytokine levels. In sum, our findings provide evidence suggesting that PMN-MDSC% in conjunction with the levels IL-1β, IL-27, and IL-29 could be a useful strategy to identify groups of patients with potentially unfavorable prognoses.

Breast and pancreatic cancer interrupt IRF8-dependent dendritic cell development to overcome immune surveillance

Tumors employ multiple mechanisms to evade immune surveillance. One mechanism is tumor-induced myelopoiesis, whereby the expansion of immunosuppressive myeloid cells can impair tumor immunity. As myeloid cells and conventional dendritic cells (cDCs) are derived from the same progenitors, we postulated that myelopoiesis might impact cDC development. The cDC subset, cDC1, which includes human CD141⁺ DCs and mouse CD103⁺ DCs, supports anti-tumor immunity by stimulating CD8⁺ T-cell responses. Here, to understand how cDC1 development changes during tumor progression, we investigated cDC bone marrow progenitors. We found localized breast and pancreatic cancers induce systemic decreases in cDC1s and their progenitors. Mechanistically, tumor-produced granulocyte-stimulating factor downregulates interferon regulatory factor-8 in cDC progenitors, and thus results in reduced cDC1 development. Tumor-induced reductions in cDC1 development impair anti-tumor CD8⁺ T-cell responses and correlate with poor patient outcomes. These data suggest immune surveillance can be impaired by tumor-induced alterations in cDC development.

Tumors escape the immune system through many mechanisms. Here the authors show that certain tumors inhibit anti-tumor immunity by stopping the production of conventional dendritic cells (cDCs) in the bone marrow, therefore depleting the pool of cDCs available to present antigen to CD8⁺ T cells.

New Insights into the Tumor Microenvironment Utilizing Protein Array Technology

The tumor microenvironment (TME) is a considerably heterogeneous niche, which is created by tumor cells, the surrounding tumor stroma, blood vessels, infiltrating immune cells, and a variety of associated stromal cells. Intercellular communication within this niche is driven by soluble proteins synthesized by local tumor and stromal cells and include chemokines, growth factors, interferons, interleukins, and angiogenic factors. The interaction of tumor cells with their microenvironment is essential for tumorigenesis, tumor progression, growth, and metastasis, and resistance to drug therapy. Protein arrays enable the parallel detection of hundreds of proteins in a small amount of biological sample. Recent data have demonstrated that the application of protein arrays may yield valuable information regarding the structure and functional mechanisms of the TME. In this review, we will discuss protein array technologies and their applications in TME analysis to discern pathways involved in promoting the tumorigenic phenotype.

IFN-α potentiates the direct and immune-mediated antitumor effects of epigenetic drugs on both metastatic and stem cells of colorectal cancer

Epigenetic alterations, including dysregulated DNA methylation and histone modifications, govern the progression of colorectal cancer (CRC). Cancer cells exploit epigenetic regulation to control cellular pathways, including apoptotic and metastatic signals. Since aberrations in epigenome can be pharmacologically reversed by DNA methyltransferase and histone deacetylase inhibitors, epigenetics in combination with standard agents are currently envisaged as a new therapeutic frontier in cancer, expected to overcome drug resistance associated with current treatments. In this study, we challenged this idea and demonstrated that the combination of azacitidine and romidepsin with IFN-α owns a high therapeutic potential, targeting the most aggressive cellular components of CRC, such as metastatic cells and cancer stem cells (CSCs), via tight control of key survival and death pathways. Moreover, the antitumor efficacy of this novel pharmacological approach is associated with induction of signals of immunogenic cell death. Of note, a previously undisclosed key role of IFN-α in inducing both antiproliferative and pro-apoptotic effects on CSCs of CRC was also found. Overall, these findings open a new frontier on the suitability of IFN-α in association with epigenetics as a novel and promising therapeutic approach for CRC management.

Epigenetic View on Interferon γ Signalling in Tumour Cells

IFN-γ is a pleiotropic cytokine crucial for both innate and adaptive immunity, which also plays a critical role in immunological surveillance of cancer. Genetic defects or gene silencing in the IFN-γ signal transduction pathways as well as in the expression of IFN-γ-regulated genes represent frequent mechanisms by which tumour cells can escape from immune responses. Epigenetic control of the IFN-γ signalling pathway activation associated with epigenetic changes in the corresponding regulatory gene regions, such as chromatin remodelling, histone acetylation and methylation, and DNA demethylation is frequently dysregulated in tumour cells. Epigenetic silencing of the IFN-γ regulatory pathway components, as well as of the IFN-γ-regulated genes crucial for tumour cell recognition or induction of anti-tumour immune responses, has been documented in various cancer models. Expression of both IFN-γ signalling pathway components and selected IFN-γ-regulated genes can be influenced by epigenetic modifiers, namely DNA methyltransferase and histone deacetylase inhibitors. These agents thus can mimic, restore, or boost the immunomodulatory effects of IFN-γ in tumour cells, which can contribute to their anti-tumour therapeutic efficacies and justifies their potential use in combined epigenetic therapy with immunotherapeutic approaches.

Neutrophils and PMN-MDSC: Their biological role and interaction with stromal cells

Neutrophils and polymorphonucler myeloid-derived suppressor cells (PMN-MDSC) share origin and many morphological and phenotypic features. However, they have different biological role. Neutrophils are one of the major mechanisms of protection against invading pathogens, whereas PMN-MDSC have immune suppressive activity and restrict immune responses in cancer, chronic infectious disease, trauma, sepsis, and many other pathological conditions. Although in healthy adult individuals, PMN-MDSC are not or barely detectable, in patients with cancer and many other diseases they accumulate at various degree and co-exist with neutrophils. Recent advances allow for better distinction of these cells and better understanding of their biological role. Accumulating evidence indicates PMN-MDSC as pathologically activated neutrophils, with important role in regulation of immune responses. In this review, we provide an overview on the definition and characterization of PMN-MDSC and neutrophils, their pathological significance in a variety of diseases, and their interaction with other stromal components.

Antitumor Effects of Epidrug/IFNα Combination Driven by Modulated Gene Signatures in Both Colorectal Cancer and Dendritic Cells

Colorectal cancer results from the progressive accumulation of genetic and epigenetic alterations. IFN signaling defects play an important role in the carcinogenesis process, in which the inability of IFN transcription regulatory factors (IRF) to access regulatory sequences in IFN-stimulated genes (ISG) in tumors and in immune cells may be pivotal. We reported that low-dose combination of two FDA-approved epidrugs, azacytidine (A) and romidepsin (R), with IFNα2 (ARI) hampers the aggressiveness of both colorectal cancer metastatic and stem cells in vivo and triggers immunogenic cell death signals that stimulate dendritic cell (DC) function. Here, we investigated the molecular signals induced by ARI treatment and found that this drug combination increased the accessibility to regulatory sequences of ISGs and IRFs that were epigenetically silenced in both colorectal cancer cells and DCs. Likewise, specific ARI-induced histone methylation and acetylation changes marked epigenetically affected ISG promoters in both metastatic cancer cells and DCs. Analysis by ChIP-seq confirmed such ARI-induced epigenetically regulated IFN signature. The activation of this signal endowed DCs with a marked migratory capability. Our results establish a direct correlation between reexpression of silenced ISGs by epigenetic control and ARI anticancer activity and provide new knowledge for the development of innovative combined therapeutic strategies for colorectal cancer. Cancer Immunol Res; 5(7); 604-16. ©2017 AACR.

3D Microfluidic model for evaluating immunotherapy efficacy by tracking dendritic cell behaviour toward tumor cells

Immunotherapy efficacy relies on the crosstalk within the tumor microenvironment between cancer and dendritic cells (DCs) resulting in the induction of a potent and effective antitumor response. DCs have the specific role of recognizing cancer cells, taking up tumor antigens (Ags) and then migrating to lymph nodes for Ag (cross)-presentation to naïve T cells. Interferon-α-conditioned DCs (IFN-DCs) exhibit marked phagocytic activity and the special ability of inducing Ag-specific T-cell response. Here, we have developed a novel microfluidic platform recreating tightly interconnected cancer and immune systems with specific 3D environmental properties, for tracking human DC behaviour toward tumor cells. By combining our microfluidic platform with advanced microscopy and a revised cell tracking analysis algorithm, it was possible to evaluate the guided efficient motion of IFN-DCs toward drug-treated cancer cells and the succeeding phagocytosis events. Overall, this platform allowed the dissection of IFN-DC-cancer cell interactions within 3D tumor spaces, with the discovery of major underlying factors such as CXCR4 involvement and underscored its potential as an innovative tool to assess the efficacy of immunotherapeutic approaches.

Hydrogels bearing bioengineered mimetic embryonic microenvironments for tumor reversion

Embryonic microenvironments can reverse the metastatic phenotype of aggressive tumors by inhibiting the Nodal signaling pathway. Here, we hypothesize that embryonic microenvironments can be transplanted for the purpose of oncotherapy. We report the development of an injectable bioactive hydrogel system containing the key antagonists of Nodal signaling-Cripto-1 receptor antibodies (2B11)-for the creation of embryonic microenvironments and the examination of their effect on tumor reversion treatment using a mouse model. Our in vitro results show that the hydrogel system can reduce the mitochondrial membrane potential of MDA-MB-231 and MCF-7, promote cell apoptosis, and reduce the invasive ability of cells. Our in vivo results illustrate that the hydrogel system can significantly inhibit tumor growth in both breast cancer and melanoma tumor-bearing mouse models, as well as transform the cell morphology of melanoma B16 cells to melanin-like cells. Furthermore, the results of the up-regulation of tumor suppressor genes and the down-regulation of oncogenes by high-throughput sequencing confirm that the developed system can also selectively turn on some tumor suppressor genes and turn off certain oncogenes so as to prompt the benign reversion of the tumor phenotype. Taken together, our results demonstrate the injectable biomaterial system is able to create an effective microenvironment for melanoma and breast tumor therapy.

Context Matters: Distinct Disease Outcomes as a Result of Crebbp Hemizygosity in Different Mouse Bone Marrow Compartments

Perturbations in CREB binding protein (CREBBP) are associated with hematopoietic malignancies, including myelodysplastic syndrome (MDS). Mice hemizygous for Crebbp develop myelodysplasia with proliferative features, reminiscent of human MDS/myeloproliferative neoplasm-unclassifiable (MDS/MPN-U), and a proportion goes on to develop acute myeloid leukemia (AML). We have also shown that the Crebbp+/- non-hematopoietic bone marrow microenvironment induces excessive myeloproliferation of wild-type cells. We now report that transplantation of unfractionated Crebbp+/- bone marrow into wild-type recipients resulted in either early-onset AML or late-onset MDS and MDS/MPN-U. In contrast, purified Lin-Sca-1+c-Kit++ cells primarily gave rise to MDS with occasional transformation to AML. Furthermore, Crebbp+/- common myeloid progenitors and granulocyte/macrophage progenitors could trigger skewed myelopoiesis, myelodysplasia and late-onset AML. Surprisingly, the phenotypically abnormal cells were all of wild-type origin. MDS, MPN and AML can thus all be transferred from Crebbp+/- BM to wild-type hosts but fractionated bone marrow does not recapitulate the full disease spectrum of whole bone marrow, indicating that not only mutational status but also cellular context contribute to disease outcome. This has important consequences for structuring and interpreting future investigations into the underlying mechanisms of myeloid malignancies as well as for their treatment.

Immunoregulatory roles of versican proteolysis in the myeloma microenvironment

Myeloma immunosurveillance remains incompletely understood. We have demonstrated proteolytic processing of the matrix proteoglycan, versican (VCAN), in myeloma tumors. Whereas intact VCAN exerts tolerogenic activities through Toll-like receptor 2 (TLR2) binding, the immunoregulatory consequences of VCAN proteolysis remain unknown. Here we show that human myeloma tumors displaying CD8(+) infiltration/aggregates underwent VCAN proteolysis at a site predicted to generate a glycosaminoglycan-bereft N-terminal fragment, versikine Myeloma-associated macrophages (MAMs), rather than tumor cells, chiefly produced V1-VCAN, the precursor to versikine, whereas stromal cell-derived ADAMTS1 was the most robustly expressed VCAN-degrading protease. Purified versikine induced early expression of inflammatory cytokines interleukin 1β (IL-1β) and IL-6 by human myeloma marrow-derived MAMs. We show that versikine signals through pathways both dependent and independent of Tpl2 kinase, a key regulator of nuclear factor κB1-mediated MAPK activation in macrophages. Unlike intact VCAN, versikine-induced Il-6 production was partially independent of Tlr2. In a model of macrophage-myeloma cell crosstalk, versikine induced components of "T-cell inflammation," including IRF8-dependent type I interferon transcriptional signatures and T-cell chemoattractant CCL2. Thus the interplay between stromal cells and myeloid cells in the myeloma microenvironment generates versikine, a novel bioactive damage-associated molecular pattern that may facilitate immune sensing of myeloma tumors and modulate the tolerogenic consequences of intact VCAN accumulation. Therapeutic versikine administration may potentiate T-cell-activating immunotherapies.

Transcriptional regulation of myeloid-derived suppressor cells

Myeloid-derived suppressor cells are a heterogeneous group of pathologically activated immature cells that play a major role in the negative regulation of the immune response in cancer, autoimmunity, many chronic infections, and inflammatory conditions, as well as in the regulation of tumor angiogenesis, tumor cell invasion, and metastases. Accumulation of myeloid-derived suppressor cells is governed by a network of transcriptional regulators that could be combined into 2 partially overlapping groups: factors promoting myelopoiesis and preventing differentiation of mature myeloid cells and factors promoting pathologic activation of myeloid-derived suppressor cells. In this review, we discuss the specific nature of these factors and their impact on myeloid-derived suppressor cell development.

Regulation of chemokine expression in the tumor microenvironment

Chemokines are chemotactic cytokines critical for homeostatic and inflammation-induced trafficking of leukocytes during immune responses, hematopoesis, wound healing, and tumorigenesis. Despite three decades of intensive study of the chemokine network, the molecular mechanisms regulating chemokine expression during tumor growth are not well understood. In this review, we focus on the role of chemokines in both tumor growth and anti-tumor immune responses and on molecular mechanisms employed by tumor cells to regulate chemokine expression in the tumor microenvironment. Multiple mechanisms used by tumors to regulate chemokine production, including those revealed by very recent studies (such as DNA methylation or post-translational nitrosylation of chemokines) are discussed. Concluding the review, we discuss how understanding of these regulatory mechanisms can be used in cancer therapy to suppress tumor growth and/or to promote immune-mediated eradication of tumors.

Cancer-driven dynamics of immune cells in a microfluidic environment

Scope of the present work is to infer the migratory ability of leukocytes by stochastic processes in order to distinguish the spontaneous organization of immune cells against an insult (namely cancer). For this purpose, spleen cells from immunodeficient mice, selectively lacking the transcription factor IRF-8 (IRF-8 knockout; IRF-8 KO), or from immunocompetent animals (wild-type; WT), were allowed to interact, alternatively, with murine B16.F10 melanoma cells in an ad hoc microfluidic environment developed on a LabOnChip technology. In this setting, only WT spleen cells were able to establish physical interactions with melanoma cells. Conversely, IRF-8 KO immune cells exhibited poor dynamical reactivity towards the neoplastic cells. In the present study, we collected data on the motility of these two types of spleen cells and built a complete set of observables that recapitulate the biological complexity of the system in these experiments. With remarkable accuracy, we concluded that the IRF-8 KO cells performed pure uncorrelated random walks, while WT splenocytes were able to make singular drifted random walks that collapsed on a straight ballistic motion for the system as a whole, hence giving rise to a highly coordinate response. These results may provide a useful system to quantitatively analyse the real time cell-cell interactions and to foresee the behavior of immune cells with tumor cells at the tissue level.

Cancer subclonal genetic architecture as a key to personalized medicine

The future of personalized oncological therapy will likely rely on evidence-based medicine to integrate all of the available evidence to delineate the most efficacious treatment option for the patient. To undertake evidence-based medicine through use of targeted therapy regimens, identification of the specific underlying causative mutation(s) driving growth and progression of a patient's tumor is imperative. Although molecular subtyping is important for planning and treatment, intraclonal genetic diversity has been recently highlighted as having significant implications for biopsy-based prognosis. Overall, delineation of the clonal architecture of a patient's cancer and how this will impact on the selection of the most efficacious therapy remain a topic of intense interest.

Tumor-induced perturbations of cytokines and immune cell networks

Until recently, the intrinsically high level of cross-talk between immune cells, the complexity of immune cell development, and the pleiotropic nature of cytokine signaling have hampered progress in understanding the mechanisms of immunosuppression by which tumor cells circumvent native and adaptive immune responses. One technology that has helped to shed light on this complex signaling network is the cytokine antibody array, which facilitates simultaneous screening of dozens to hundreds of secreted signal proteins in complex biological samples. The combined applications of traditional methods of molecular and cell biology with the high-content, high-throughput screening capabilities of cytokine antibody arrays and other multiplexed immunoassays have revealed a complex mechanism that involves multiple cytokine signals contributed not just by tumor cells but by stromal cells and a wide spectrum of immune cell types. This review will summarize the interactions among cancerous and immune cell types, as well as the key cytokine signals that are required for tumors to survive immunoediting in a dormant state or to grow and spread by escaping it. Additionally, it will present examples of how probing secreted cell-cell signal networks in the tumor microenvironment (TME) with cytokine screens have contributed to our current understanding of these processes and discuss the implications of this understanding to antitumor therapies.

Histone deacetylase sirtuin 1 deacetylates IRF1 protein and programs dendritic cells to control Th17 protein differentiation during autoimmune inflammation

The type III histone deacetylase Sirt1 has recently emerged as a critical immune regulator by suppressing T cell immunity and macrophage activation during inflammation, but its role in dendritic cells (DCs) remains unknown. Here, we show that mice with genetic Sirt1 deletion specifically in DCs are resistant to MOG-induced experimental autoimmune encephalomyelitis. Loss of Sirt1 functions in DCs enhances their ability to produce IL-27 and interferon β (IFN-β). Co-cultivation of Sirt1-null DCs with CD4(+) T cells inhibited Th17 differentiation, which is reversed by anti-IL27 and anti-IFN-β neutralization antibodies. Sirt1 antagonizes acetylation of IRF1, a transcription factor that drives IL-27 production. Genetic deletion of IRF1 in Sirt1-null DCs abolishes IL-27 production and suppresses Th17 differentiation. Our results show that the histone deacetylase Sirt1 programs DCs to regulate Th17 differentiation during inflammation.

Overcoming intratumor heterogeneity of polygenic cancer drug resistance with improved biomarker integration

Improvements in technology and resources are helping to advance our understanding of cancer-initiating events as well as factors involved with tumor progression, adaptation, and evasion of therapy. Tumors are well known to contain diverse cell populations and intratumor heterogeneity affords neoplasms with a diverse set of biologic characteristics that can be used to evolve and adapt. Intratumor heterogeneity has emerged as a major hindrance to improving cancer patient care. Polygenic cancer drug resistance necessitates reconsidering drug designs to include polypharmacology in pursuit of novel combinatorial agents having multitarget activity to overcome the diverse and compensatory signaling pathways in which cancer cells use to survive and evade therapy. Advances will require integration of different biomarkers such as genomics and imaging to provide for more adequate elucidation of the spatially varying location, type, and extent of diverse intratumor signaling molecules to provide for a rationale-based personalized cancer medicine strategy.

The dual role of IRF8 in cancer immunosurveillance

For a long time, the transcription factor interferon-regulatory factor 8 (IRF8) has been recognized as a masterpiece for the development of myeloid cells, and its role as a central regulator of immune responses has now been clarified. IRF8 is also critical for tumor progression, suggesting its fundamental relevance in multiple aspects of cancer immunosurveillance.

The tumor microenvironment: a pitch for multiple players

The cancer microenvironment may be conceptually regarded as a pitch where the main players are resident and non-resident cellular components, each covering a defined role and interconnected by a complex network of soluble mediators. The crosstalk between these cells and the tumor cells within this environment crucially determines the fate of tumor progression. Immune cells that infiltrate the tumor bed are transported there by blood circulation and exert a variety of effects, either counteracting or favoring tumor outgrowth. Here, we review and discuss the multiple populations composing the tumor bed, with special focus on immune cells subsets that positively or negatively dictate neoplastic progression. In this scenario, the contribution of cancer stem cells within the tumor microenvironment will also be discussed. Finally, we illustrate recent advances on new integrated approaches to investigate the tumor microenvironment in vitro.