CXCL10 alters the tumour immune microenvironment and disease progression in a syngeneic murine model of high-grade serous ovarian cancer

Utilizing network pharmacology and experimental validation to explore the mechanisms of the Qijiafuzheng formula promoting CD8+ T-cell infiltration in the microenvironment of lung adenocarcinoma through STAT1/CXCL10

Qijiafuzheng formula (QJFZF), a Traditional Chinese Medicine used to treat lung cancer and mitigate chemotherapy side effects, was studied to clarify its impact on the tumor immune microenvironment (TIME). Using network pharmacology and experimental validation, 39 overlapping targets were identified from 579 QJFZF-related and 752 lung adenocarcinoma (LUAD)-TIME targets. Key genes (CCL3, IL10, CXCL10, FOXP3, CD86) correlated negatively with tumor purity and positively with CD8+ T-cell infiltration. CXCL10 emerged as the core target, with experiments showing QJFZF activates the STAT1/CXCL10 pathway to enhance CD8+ T-cell recruitment in LUAD-TIME. This study elucidates QJFZF's immunomodulatory mechanisms, supporting its clinical application.

A Novel Chimeric Oncolytic Virus Mediates a Multifaceted Cellular Immune Response in a Syngeneic B16 Melanoma Model

BACKGROUND/OBJECTIVES

Oncolytic virotherapy is a promising approach in cancer immunotherapy. We have previously described a recombinant hybrid oncolytic virus (OV), VSV-NDV, which has a favorable safety profile and therapeutic immunogenicity, leading to direct oncolysis, abscopal effects, and prolonged survival in syngeneic in vivo tumor models. While OVs are known to mediate systemic anti-tumor immune responses, the detailed characterization of local and systemic immune responses to fusogenic oncolytic virotherapy remains unexplored.

METHODS AND RESULTS

We analyzed immune cell compartments in the spleen, blood, tumor-draining lymph nodes (TDLNs), and tumors over the course of VSV-NDV therapy in a bilateral syngeneic melanoma mouse model. Our results revealed significant local infiltration and activation of T lymphocytes in tumors and globally in the blood and spleen. Notably, in vivo CD8+ T cell depletion led to complete abrogation of the tumor response, highlighting the crucial role of T cells in promoting the therapeutic effects of oncolytic VSV-NDV. In vitro co-culture experiments enabled the interrogation of human immune cell responses to VSV-NDV-mediated oncolysis. Human peripheral blood mononuclear cells (PBMCs) were efficiently stimulated by exposure to VSV-NDV-infected cancer cells, which recapitulates the in vivo murine findings.

CONCLUSIONS

Taken together, these data characterize a broad anti-tumor immune cell response to oncolytic VSV-NDV therapy and suggest that CD8+ T cells play a decisive role in therapeutic outcome, which supports the further development of this chimeric vector as a multimechanistic immunotherapy for solid cancers.

Integrated immuno-transcriptomic analysis of ovarian cancer identifies a four-chemokine-dominated subtype with antitumor immune-active phenotype and favorable prognosis

BACKGROUND

Ovarian cancer (OV) is a heterogeneous disease but has traditionally been treated as an immunologically cold malignancy. The relationship between the immune-active cancer phenotype typified by a T helper 1 (Th-1) immune response and clinical outcome in OV remains uncertain.

METHODS

A cohort-scale compendium of transcriptomic data from 2850 OV samples from 19 individual datasets was compiled for integrative immuno-transcriptomic analysis. The immunological constant of rejection was used as a metric to assess the Th-1/cytotoxic response orientation and investigate the clinical-biological significance of immune polarization towards a Th-1 immune response. Single-cell RNA sequencing data from 39 OV samples were analyzed to elucidate the variability of the immune microenvironment, and immunohistochemical validation was performed on 39 samples from the Harbin Medical University Cancer Hospital.

RESULTS

Our results demonstrated the prognostic significance of a Th-1/cytotoxic immune profile within the tumor microenvironment (TME) using the immunological constant of rejection classification to OV samples. Specifically, patients with tumors expressing high levels of ICR markers showed significantly improved survival. A gene panel consisting of four chemokines (CXCL9, CXCL10, CXCL11 and CXCL13) was identified as critical players in mediating the establishment of an active T-cell-inflamed antitumor phenotype. This 4-chemokine signature, which was extensively validated in external multicenter cohorts through transcriptomic profiling and in an independent in-house cohort through immunohistochemistry, introduced a novel immune classification in OV and identified a chemokine-dominated subtype associated with an active antitumor immune phenotype and favorable prognosis. Single-cell transcriptomic analysis revealed that chemokine-dominated tumors increase CXCR3 + NK and T cell recruitment to the TME primarily through the overexpression of macrophage-derived CXCL9/10/11.

CONCLUSIONS

This study provides new insights into understanding immune heterogeneity within the TME and paves the way for tailoring appropriate therapeutic interventions for patients with differing immune profiles.

Radiomics Signatures Based on Computed Tomography for Noninvasive Prediction of CXCL10 Expression and Prognosis in Ovarian Cancer

BACKGROUND

Ovarian cancer (OC) is an aggressive gynecological tumor usually diagnosed with malignant ascites and even observed widespread metastasis or distant spread.

AIMS

We aimed to develop and identify radiomics models according to computed tomography (CT) for preoperative prediction of CXCL10 expression and prognosis in patients with OC.

METHODS

Genomic data with CT images and corresponding clinicopathological parameters were extracted from The Cancer Imaging Archive (TCIA) and The Cancer Genome Atlas (TCGA). To analyze the prognosis, we carried out the univariate Cox regression analysis (UCRA), multivariate Cox regression analysis (MCRA), and Kaplan-Meier (KM) analysis. For the data reduction, logistic regression, operator regression, least absolute shrinkage selection, radiomic feature construction, and feature selection were utilized. The predictive performance of the radiomic signatures was assessed using the analyses of the receiver operating characteristic (ROC) curve, decision curve (DCA), and precision-recall (PR) curve. To evaluate the correlation between the radiomic score (Rad-score) and CXCL10 expression, the Wilcoxon rank-sum test was applied.

RESULTS

Three radiomics models effectively predicted CXCL10 expression levels (AUC = 0.791, 0.748, and 0.718 for the set of training; AUC = 0.761, 0.746, and 0.701 for the set of validation). A higher Rad-score significantly correlated with upregulated CXCL10 expression.

CONCLUSION

CXCL10 expression can be predicted noninvasively and preoperatively via radiomic signatures based on contrast-enhanced CT images.

CXCL10 Recruitment of γδ T Cells into the Hypoxic Bone Marrow Environment Leads to IL17 Expression and Multiple Myeloma Progression

In multiple myeloma (MM), bone marrow stromal cells (BMSC) shape a unique niche within the bone marrow, promoting T-cell dysfunction and driving MM progression; however, the precise underlying mechanisms remain elusive. Here, we show that BMSC-mediated reprogramming of MM cells led to heightened production of CXCL10. CXCL10 orchestrated the recruitment of γδ T cells into the bone marrow, and this was observed in both the Vk*MYC and 5TGM1 mouse models of MM, as well as in patients experiencing refractory or relapsed MM. Furthermore, the dysfunctional γδ T cells in the MM bone marrow niche exhibited increased PD-1 expression and IL17 production. In the Vk*MYC mouse model, MM-associated bone lesions and mortality were markedly alleviated in Tcrd-/- mice, and MM disease progression could be rescued in these mice upon transplantation of γδ T cells expanded from wild-type mice, but not from Il17-/- mice. Mechanistically, the hypoxic microenvironment prevailing in the MM bone marrow niche stimulated the expression of steroid receptor coactivator 3 (SRC-3) in γδ T cells, which in turn interacted with the transcriptional factor RORγt, promoting Il17 transcription. Pharmacologic inhibition of SRC-3 utilizing SI-2 effectively suppressed Il17A expression in γδ T cells, leading to alleviation of MM progression in the murine models and enhancing the anti-multiple myeloma efficacy of bortezomib. Our results illuminated the bone marrow microenvironment's involvement in provoking γδ T-cell dysfunction throughout MM progression and suggest SRC-3 inhibition as a promising strategy to enhance the effectiveness of immunotherapies targeting γδ T cells.

Carbon Ions Suppress Angiogenesis and Lung Metastases in Melanoma by Targeting CXCL10

Carbon-ion radiotherapy (CIRT) enhanced local control in patients with malignant melanoma. In several in vitro studies, carbon ions (C ions) have been also shown to decrease the metastatic potential of melanoma cells. CXC motif 10 (CXCL10) has been shown to play a crucial role in regulating tumor metastasis and it significantly increase in human embryonic kidney cells after heavy ion irradiations. This study sought to explore the regulatory effect of C ions on melanoma metastasis, emphasizing the role of CXCL10 in this process. To explore the potential regulatory effect of C ions on tumor metastasis in vivo, we developed a lung metastasis mouse model by injecting B16F10 cells into the footpad and subjected all mice to treatment with X rays and C ions. Subsequently, a series of assays, including histopathological analysis, enzyme-linked immunosorbent assay, real-time PCR, and western blotting, were conducted to assess the regulatory effects of C ions on melanoma. Our results showed that mice treated with C ions exhibited significantly less tumor vascularity, enhanced tumor necrosis, alleviated lung metastasis, and experienced longer survival than X-ray irradiated mice. Moreover, VEGF expression in B16F10 cells was significantly reduced by C-ion treatment, which could be alleviated by CXCL10 knockdown in vitro. Further investigations revealed that co-culturing with HUVECs resulted in a significant inhibition of proliferation, migration, and tube formation ability in the C-ion treated group, while the opposite effect was observed in the C-ion treated with si-CXCL10 group. In conclusion, our findings demonstrate that treatment with carbon-ion radiation can suppress angiogenesis and lung metastases in melanoma by specifically targeting CXCL10. These results suggest the potential utility of carbon ions in treating melanoma.

The role of CXCL family members in different diseases

Chemokines are a large family mediating a lot of biological behaviors including chemotaxis, tumor growth, angiogenesis and so on. As one member of this family, CXC subfamily possesses the same ability. CXC chemokines can recruit and migrate different categories of immune cells, regulate tumor's pathological behaviors like proliferation, invasion and metastasis, activate angiogenesis, etc. Due to these characteristics, CXCL subfamily is extensively and closely associated with tumors and inflammatory diseases. As studies are becoming more and more intensive, CXCLs' concrete roles are better described, and CXCLs' therapeutic applications including biomarkers and targets are also deeply explained. In this review, the role of CXCL family members in various diseases is summarized.

Tumor and local lymphoid tissue interaction determines prognosis in high-grade serous ovarian cancer

Tertiary lymphoid structure (TLS) is associated with prognosis in copy-number-driven tumors, including high-grade serous ovarian cancer (HGSOC), although the function of TLS and its interaction with copy-number alterations in HGSOC are not fully understood. In the current study, we confirm that TLS-high HGSOC patients show significantly better progression-free survival (PFS). We show that the presence of TLS in HGSOC tumors is associated with B cell maturation and cytotoxic tumor-specific T cell activation and proliferation. In addition, the copy-number loss of IL15 and CXCL10 may limit TLS formation in HGSOC; a list of genes that may dysregulate TLS function is also proposed. Last, a radiomics-based signature is developed to predict the presence of TLS, which independently predicts PFS in both HGSOC patients and immune checkpoint inhibitor (ICI)-treated non-small cell lung cancer (NSCLC) patients. Overall, we reveal that TLS coordinates intratumoral B cell and T cell response to HGSOC tumor, while the cancer genome evolves to counteract TLS formation and function.

The Role of STATs in Ovarian Cancer: Exploring Their Potential for Therapy

Ovarian cancer (OvCa) is a deadly gynecologic malignancy that presents many clinical challenges due to late-stage diagnoses and the development of acquired resistance to standard-of-care treatment protocols. There is an increasing body of evidence suggesting that STATs may play a critical role in OvCa progression, resistance, and disease recurrence, and thus we sought to compile a comprehensive review to summarize the current state of knowledge on the topic. We have examined peer reviewed literature to delineate the role of STATs in both cancer cells and cells within the tumor microenvironment. In addition to summarizing the current knowledge of STAT biology in OvCa, we have also examined the capacity of small molecule inhibitor development to target specific STATs and progress toward clinical applications. From our research, the best studied and targeted factors are STAT3 and STAT5, which has resulted in the development of several inhibitors that are under current evaluation in clinical trials. There remain gaps in understanding the role of STAT1, STAT2, STAT4, and STAT6, due to limited reports in the current literature; as such, further studies to establish their implications in OvCa are necessitated. Moreover, due to the deficiency in our understanding of these STATs, selective inhibitors also remain elusive, and therefore present opportunities for discovery.

In-depth analysis of the expression and functions of signal transducers and activators of transcription in human ovarian cancer

BACKGROUND

Signal transducers and activators of transcription (STAT) transcription factors, a family of genes encoding transcription factors, have been linked to the development of numerous types of tumors. However, there is a relative paucity of a comprehensive investigation of the expression and functional analysis of STATs in ovarian cancer (OV).

METHOD

Gene expression profile interaction analysis (GEPI2A), Metascape, The Cancer Genome Atlas (TCGA), Kaplan-Meier Plotter, Linkedomics, and CancerSEA databases were used for expression analysis and functional enrichment of STATs in ovarian cancer patients. We screened potential predictive genes and evaluated their prognostic value by constructing the minor absolute shrinkage and selection operator (LASSO) Cox proportional risk regression model. We explored STAT5A expression and its effects on cell invasion using ovarian cancer cells and a tissue microarray.

RESULTS

The expression level of STAT1 was higher, but that of STAT2-6 was lower in cancerous ovarian tissues compared to normal tissues, which were closely associated with the clinicopathological features. Low STAT1, high STAT4, and 6 mRNA levels indicated high overall survival. STAT1, 3, 4, and 5A were collectively constructed as prognostic risk models. STAT3, and 5A, up-regulating in the high-risk group, were regarded as risk genes. In subsequent validation, OV patients with a low level of P-STAT5A but not low STAT5A had a longer survival time (P=0.0042). Besides, a negative correlation was found between the expression of STAT5A and invasion of ovarian cancer cells (R= -0.38, p < 0.01), as well as DNA repair function (R= -0.36, p < 0.01). Furthermore, transient overexpression of STAT5A inhibited wound healing (21.8%, P<0.0001) and cell migration to the lower chamber of the Transwell system (29.3%, P<0.0001), which may be achieved by regulating the expression of MMP2.

CONCLUSION

It is suggested that STAT1, STAT4, and STAT6 may be potential targets for the proper treatment of ovarian cancer. STAT5A and P-STAT5A, biomarkers identified in ovarian cancer, may offer new perspectives for predicting prognosis and assessing therapeutic effects.

Dual G9A/EZH2 Inhibition Stimulates Antitumor Immune Response in Ovarian High-Grade Serous Carcinoma

Ovarian high-grade serous carcinoma (HGSC) prognosis correlates directly with presence of intratumoral lymphocytes. However, cancer immunotherapy has yet to achieve meaningful survival benefit in patients with HGSC. Epigenetic silencing of immunostimulatory genes is implicated in immune evasion in HGSC and re-expression of these genes could promote tumor immune clearance. We discovered that simultaneous inhibition of the histone methyltransferases G9A and EZH2 activates the CXCL10-CXCR3 axis and increases homing of intratumoral effector lymphocytes and natural killer cells while suppressing tumor-promoting FoxP3+ CD4 T cells. The dual G9A/EZH2 inhibitor HKMTI-1-005 induced chromatin changes that resulted in the transcriptional activation of immunostimulatory gene networks, including the re-expression of elements of the ERV-K endogenous retroviral family. Importantly, treatment with HKMTI-1-005 improved the survival of mice bearing Trp53-/- null ID8 ovarian tumors and resulted in tumor burden reduction. These results indicate that inhibiting G9A and EZH2 in ovarian cancer alters the immune microenvironment and reduces tumor growth and therefore positions dual inhibition of G9A/EZH2 as a strategy for clinical development.

Minimally Invasive Preclinical Monitoring of the Peritoneal Cavity Tumor Microenvironment

Intraperitoneal (i.p.) experimental models in mice can recapitulate the process of i.p. dissemination in abdominal cancers and may help uncover critical information about future successful clinical treatments. i.p. cellular composition is studied in preclinical models addressing a wide spectrum of other pathophysiological states such as liver cirrhosis, infectious disease, autoimmunity, and aging. The peritoneal cavity is a multifaceted microenvironment that contains various immune cell populations, including T, B, NK, and various myeloid cells, such as macrophages. Analysis of the peritoneal cavity is often obtained by euthanizing mice and performing terminal peritoneal lavage. This procedure inhibits continuous monitoring of the peritoneal cavity in a single mouse and necessitates the usage of more mice to assess the cavity at multiple timepoints, increasing the cost, time, and variability of i.p. studies. Here, we present a simple, novel method termed in vivo intraperitoneal lavage (IVIPL) for the minimally invasive monitoring of cells in the peritoneal cavity of mice. In this proof-of-concept, IVIPL provided real-time insights into the i.p. tumor microenvironment for the development and study of ovarian cancer therapies. Specifically, we studied CAR-T cell therapy in a human high-grade serous ovarian cancer (HGSOC) xenograft mouse model, and we studied the immune composition of the i.p. tumor microenvironment (TME) in a mouse HGSOC syngeneic model.

Screening of CXC chemokines in the microenvironment of ovarian cancer and the biological function of CXCL10

BACKGROUND

This study aims to screen and identify the biological functions and prognostic value of CXC chemokines in ovarian cancer (OC) through bioinformatics and molecular biology methods, and to provide data support for the selection of biomarkers and prognostic analysis of OC.

METHODS

In this study, GEO, ONCOMINE, GEPIA, cBioPortal, GeneMANIA, Metascape, STRING, TRRUST, and TIMER databases were used to study CXC chemokines. Angiogenesis and T cell killing assay were used to detect the effect of CXCL10 on tumor cell immunity and angiogenesis. Real-time quantitative PCR (qRT-PCR), immunoblotting, and ectopic tumor formation experiments were used to verify the effect of CXCL10 on ovarian cancer tumors.

RESULTS

We found that CXCL1, CXCL10, CXCL11, CXCL13, and CXCL14 were significantly upregulated in OC samples compared with normal tissues. Our data showed that there was a relationship between the expression of CXC chemokines and the infiltration of six types of immune cells significant correlation. In vitro assay confirmed that overexpression of CXCL10 could enhance the killing effect of T cells and inhibit angiogenesis. Further in vivo assay had shown that CXCL10 could affect the progression of ovarian cancer by increasing the expression of cytotoxic T cells and inhibiting angiogenesis.

CONCLUSION

In conclusion, we hope that our data will provide new insights into the development of immunotherapy and the selection of prognostic markers for patients with OC.

Identification of an Immune-Related Prognostic Gene CLEC5A Based on Immune Microenvironment and Risk Modeling of Ovarian Cancer

Objective: To understand the immune characteristics of the ovarian cancer (OC) microenvironment and explore the differences of immune-related molecules and cells to establish an effective risk model and identify the molecules that significantly affected the immune response of OC, to help guide the diagnosis. Methods: First, we calculate the TMEscore which reflects the immune microenvironment, and then analyze the molecular differences between patients with different immune characteristics, and determine the prognostic genes. Then, the risk model was established by least absolute shrinkage and selection operator (LASSO) analysis and combined with clinical data into a nomogram for diagnosis and prediction. Subsequently, the potential gene CLEC5A influencing the immune response of OC was identified from the prognostic genes by integrative immune-stromal analysis. The genomic alteration was explored based on copy number variant (CNV) and somatic mutation data. Results: TMEscore was a prognostic indicator of OC. The prognosis of patients with high TMEscore was better. The risk model based on immune characteristics was a reliable index to predict the prognosis of patients, and the nomogram could comprehensively evaluate the prognosis of patients. Besides, CLEC5A was closely related to the abundance of immune cells, immune response, and the expression of immune checkpoints in the OC microenvironment. OC cells with high expression of CLEC5A increased the polarization of M2 macrophages. CLEC5A expression was significantly associated with TTN and CDK12 mutations and affected the copy number of tumor progression and immune-related genes. Conclusion: The study of immune characteristics in the OC microenvironment and the risk model can reveal the factors affecting the prognosis and guide the clinical hierarchical treatment. CLEC5A can be used as a potential key gene affecting the immune microenvironment remodeling of OC, which provides a new perspective for improving the effect of OC immunotherapy.

Immunology and Immune Checkpoint Inhibition in Ovarian Cancer - Current Aspects

In the last decade immunotherapies such as immune checkpoint blockade (ICB) against the PD-1/PD-L1 system have revolutionised the treatment of numerous entities. To date, ovarian cancer has benefited very little from this success story. Possible causes include a rather low mutational burden compared to other tumour types, inadequate presentation of (neo-)antigens, and increased infiltration with immunosuppressive immune cells such as regulatory T cells and tumour-associated macrophages. In the clinical trials completed to date, the response rates to PD-1/PD-L1 checkpoint inhibitors have therefore been disappointingly low as well, although isolated long-term remissions have also been observed in ovarian cancer. The task now is to find suitable predictive biomarkers as well as to identify combination partners for ICB therapy that can increase the immunogenicity of ovarian cancer or overcome immunosuppressive resistance mechanisms. This paper provides an overview of the immune milieu in ovarian cancer, its impact on the effect of ICB, and summarises the clinical trial data available to date on ICB in ovarian cancer.

The effects of T-DXd on the expression of HLA class I and chemokines CXCL9/10/11 in HER2-overexpressing gastric cancer cells

Trastuzumab deruxtecan (T-DXd), a HER2-targeting antibody–drug conjugate with a topoisomerase I inhibitor deruxtecan (DXd), exhibits an excellent anti-tumor effect in previously treated HER2-positive tumors. A recent study demonstrated that T-DXd not only suppressed tumor growth but also enhanced anti-tumor immunity through increasing the number of tumor-infiltrating CD8⁺ T cells and enhancement of major-histocompatibility-complex class I expression on tumor cells in a mouse model. However, the effect of T-DXd on anti-tumor immune responses in human cancers is largely unknown. We investigated the effect of T-DXd on the expression of HLA class I and CXCL9/10/11, T-cell chemoattractants, in HER2-positive human gastric cancer (GC) cells. We found that T-DXd significantly inhibited GC cell proliferation in a HER2-dependent manner, while it slightly increased the expression of HLA class I in HER2-positive GC cells. Moreover, we revealed that T-DXd significantly induced mRNA expression of CXCL9/10/11 in HER2-positive GC cells. T-DXd-triggered up-regulation of these chemokines was mediated through the activation of DNA damage signaling pathways. These results suggest that T-DXd triggers anti-tumor immune responses at least in part through induction of the expression of HLA class I and CXCL9/10/11 on HER2-positive GC cells, resulting in the enhancement of anti-tumor immunity in human GC.

Identification of CXCL10-Relevant Tumor Microenvironment Characterization and Clinical Outcome in Ovarian Cancer

Background

Chemokines are implicated in tumor microenvironment (TME) cell infiltration. Development of ovarian cancer involves heterologous cells together with the adjacent microenvironment. Nonetheless, our understanding of the chemokine-related TME characteristics in ovarian cancer remains obscure.

Methods

In this large-scale multi-platform study of 10 microarray datasets consisting of 1,673 ovarian cancer patients, we comprehensively evaluated CXCL10 and CXCL9 expression risk classifications for predicting overall survival (OS) and TME immune characteristics. The cross-validation between a standard cohort (TCGA: The Cancer Genome Atlas) and three test cohorts (GEO: Gene-Expression Omnibus) was applied. We investigated differences in the biological functions and the underlying mechanisms between high- and low-risk classifications.

Results

We identified that evaluation of CXCL10 expression could predict the tumor development, immune cell infiltration, TME signature, genetic alteration, and patient prognosis in ovarian cancer. Low-risk classification was characterized by high CXCL10 expression and prolonged prognosis, which was positively associated with specific immune cell infiltration (i.e., T cells, DCs, aDC, and Th2 cells) and TME immune-relevant signatures. Meanwhile, the high-risk classification was defined by lower CXCL10/CXCL9 expression and relevant poor prognosis and immune infiltrations. The CXCL10-based low-risk classification was also linked to antitumor biological function of specific immune gene sets, such as IL2-STAT5 signaling. Additionally, a mutational pattern featured by enrichment of C > T transition was further identified to be associated with immune cell infiltration.

Conclusions

This work proposed a promising biomarker for evaluating TME immune characteristics and clinical outcomes in patients with ovarian cancer. Estimation of CXCL10 risk pattern sheds a novel insight on ovarian cancer TME immune characteristics and provides strategies for ovarian cancer immunotherapy.

EZH2 inhibits NK cell-mediated antitumor immunity by suppressing CXCL10 expression in an HDAC10-dependent manner

Enhancer of zeste homolog 2 (EZH2) is a histone H3 lysine 27 methyltransferase that has been shown to function as an oncogene in some cancers. Previous reports have largely focused on the ability of EZH2 to regulate cell-intrinsic tumor regulatory pathways as its mechanism-of-oncogenic action. However, the role that EZH2-mediated immune suppression plays in its oncogenic activity is not fully known. In particular, the role of natural killer (NK) cells in EZH2-driven tumor growth remains incompletely understood. Here, we demonstrate that genetic or pharmacological inhibition of EZH2 induces reexpression of the chemokine CXCL10 in hepatic tumor cells. We find that histone deacetylase 10 (HDAC10) is necessary for EZH2 recruitment to the CXCL10 promoter, leading to CXCL10 transcriptional repression. Critically, CXCL10 is necessary and sufficient for stimulating NK cell migration, and EZH2's ability to inhibit NK cell migration via CXCL10 suppression is conserved in other EZH2-dependent cancers. NK cell depletion in an immunocompetent syngeneic mouse model of hepatic tumorigenesis reverses the tumor inhibitory effects of an EZH2 inhibitor (GSK343), and inhibitor-mediated reexpression of CXCL10 is required for its tumor suppressive effects in the same mouse model. Collectively, these results reveal a decisive role for NK cells and CXCL10 in mediating the oncogenic function of EZH2.

Cocktail strategy for 'cold' tumors therapy via active recruitment of CD8+ T cells and enhancing their function

In immunotherapy, 'cold' tumors, with low T cells infiltration, hardly benefit from the treatment of immune checkpoint inhibitors (ICIs). To address this issue, we screened two 'cold' tumor models for mice with high expression of galectin-3 (Gal-3) and designed a cocktail strategy to actively recruit CD8+ T cells into the tumor microenvironment (TME), which reversed 'cold' tumors into 'hot' and remarkably elevated their ICIs-responsiveness. Gal-3, an important driving force of tumorigenesis, inhibits T cell infiltration into tumor tissue that shapes 'cold' tumor phenotype, and promotes tumor metastasis. In this respect, Gal-3 antagonist G3-C12 peptide was chosen and further loaded into poly(lactic-co-glycolic acid) (PLGA) microspheres, with the prepared G3-C12@PLGA playing a dual role of antitumor, namely, killing two birds with one stone. Specifically, G3-C12@PLGA actively recruit T cells into 'cold' tumors by rescuing IFN-γ, and simultaneously inhibit tumor metastasis induced by Gal-3. Moreover, when combined with chemotherapeutic agent (Oxaliplatin) and anti-PD-1 peptide (APP), the immunopotentiating effect of dendritic cells (DCs) was extremely improved, with T-cell depletion dramatically reversed. In vivo experiments showed that such cocktail therapy exerted remarkable antitumor effect on 'cold' breast cancer (BC) and ovarian serous cancer (OSC). These results indicated that our strategy might be promising in treating 'cold' tumors with high expression of Gal-3, which not only enhance cancer treatment outcome, but provide a new platform for the prevention of postoperative tumor recurrence/metastasis.

The Dual Role of STAT1 in Ovarian Cancer: Insight Into Molecular Mechanisms and Application Potentials

The signal transducer and activator of transcription 1 (STAT1) is a transducer protein and acts as a transcription factor but its role in ovarian cancer (OC) is not completely understood. Practically, there are two-faced effects of STAT1 on tumorigenesis in different kinds of cancers. Existing evidence reveals that STAT1 has both tumor-suppressing and tumor-promoting functions involved in angiogenesis, cell proliferation, migration, invasion, apoptosis, drug resistance, stemness, and immune responses mainly through interacting and regulating target genes at multiple levels. The canonical STAT1 signaling pathway shows that STAT1 is phosphorylated and activated by the receptor-activated kinases such as Janus kinase in response to interferon stimulation. The STAT1 signaling can also be crosstalk with other signaling such as transforming growth factor-β signaling involved in cancer cell behavior. OC is often diagnosed at an advanced stage due to symptomless or atypical symptoms and the lack of effective detection at an early stage. Furthermore, patients with OC often develop chemoresistance and recurrence. This review focuses on the multi-faced role of STAT1 and highlights the molecular mechanisms and biological functions of STAT1 in OC.

Bioinformatics Analysis of Potential Therapeutic Targets and Prognostic Biomarkers amid CXC Chemokines in Ovarian Carcinoma Microenvironment

Background

Ovarian cancer (OC) is one of the leading lethal gynecologic cancers of women around the world. More than 70% of patients are diagnosed with stage III or IV with poor outcome. This is partly because of lacking early effective screening techniques and potential biomarkers of OC. CXC chemokines in tumor microenvironment (TME) and their interaction with relative receptors can excite the downstream signaling pathways to influence tumor progression. However, the role of CXC chemokines in OC has not been identified.

Methods

ONCOMINE, GEPIA, Kaplan–Meier plotter, cBioPortal, TIMER, Metascape, and LinkedOmics were applied in our study.

Results

The transcriptional levels of CXCL1/8/9/10/11/12/13/14/16/17 were significantly elevated while CXCL3 was obviously reduced in OC vs normal ovarian tissue. CXCL8/9/11/13 were correlated with clinic pathological stage. Patients with low expression of CXCL8/9/11/13 were associated with better prognosis. We also found that CXCL3 and CXC12 could be used as potential prognostic markers of OC through Kaplan–Meier plotter. Patients with high expression of CXCL3/12 had a significantly better prognosis. Their functions focus on locomotion, signaling, response to stimulus, undergoing the process of multiorganism, immune system, biological regulation, etc. The differentiated CXC chemokines mainly participate in cytokine-cytokine receptor interaction, chemokine signaling pathway, IL-17 signaling pathway, and toll-like receptor signaling pathway. Our results showed that CXC chemokines were highly correlated with infiltration of immune cells. The kinase targets of differentially expressed CXC chemokines are mainly in ATM, LYN, LCK, PLK1, FYN, CDK2, and ATR.

Conclusions

Our results may provide a new insight for selecting precision biomarkers of targeted therapy of OC.

Oncolytic adenovirus shapes the ovarian tumor microenvironment for potent tumor-infiltrating lymphocyte tumor reactivity

Background

Ovarian cancers often contain significant numbers of tumor-infiltrating lymphocytes (TILs) that can be readily harnessed for adoptive T-cell therapy (ACT). However, the immunosuppressive ovarian tumor microenvironment and lack of tumor reactivity in TILs can limit the effectiveness of the therapy. We hypothesized that by using an oncolytic adenovirus (Ad5/3-E2F-D24-hTNFa-IRES-hIL2; TILT-123) to deliver tumor necrosis factor alpha (TNFa) and interleukin-2 (IL-2), we could counteract immunosuppression, and enhance antitumor TIL responses in ovarian cancer (OVCA).

Methods

We established ex vivo tumor cultures freshly derived from patients with advanced OVCA and evaluated the effects of Ad5/3-E2F-D24-hTNFa-IRES-hIL2 or Ad5/3-E2F-D24 (the control virus without TNFa and IL-2) on TILs, cytokine response and tumor viability. Tumor reactivity was assessed by determining interferon gamma (IFNg) response of clinically relevant TILs towards autologous T-cell-depleted ex vivo tumor cultures pretreated with or without the aforementioned oncolytic adenoviruses.

Results

Treatment of ex vivo tumor cultures with Ad5/3-E2F-D24-hTNFa-IRES-hIL2 caused a substantial rise in proinflammatory signals: increased secretion of IFNg, CXCL10, TNFa and IL-2, and concomitant activation of CD4+ and CD8+ TILs. Potent tumor reactivity was seen, as clinically relevant TIL secreted high levels of IFNg in response to autologous T-cell-depleted ovarian ex vivo tumor cultures treated with Ad5/3-E2F-D24-hTNFa-IRES-hIL2. This phenomenon was independent of PD-L1 expression in tumor cells, a factor that determined the variability of IFNg responses seen in different patient samples.

Conclusions

Overall, oncolytic adenovirus Ad5/3-E2F-D24-hTNFa-IRES-hIL2 was able to rewire the ovarian tumor microenvironment to accommodate heightened antitumor TIL reactivity. Such effects may improve the clinical effectiveness of ACT with TILs in patients with advanced OVCA.

Emerging role of mTOR in tumor immune contexture: Impact on chemokine-related immune cells migration

During the last few decades, cell-based anti-tumor immunotherapy emerged and it has provided us with a large amount of knowledge. Upon chemokines recognition, immune cells undergo rapid trafficking and activation in disease milieu, with immune cells chemotaxis being accompanied by activation of diverse intercellular signal transduction pathways. The outcome of chemokines-mediated immune cells chemotaxis interacts with the cue of mammalian target of rapamycin (mTOR) in the tumor microenvironment (TME). Indeed, the mTOR cascade in immune cells involves migration and infiltration. In this review, we summarize the available mTOR-related chemokines, as well as the characterized upstream regulators and downstream targets in immune cells chemotaxis and assign potential underlying mechanisms in each evaluated chemokine. Specifically, we focus on the involvement of mTOR in chemokine-mediated immune related cells in the balance between tumor immunity and malignancy.

A nine-gene signature related to tumor microenvironment predicts overall survival with ovarian cancer

Mounting evidence suggests that immune cell infiltration within the tumor microenvironment (TME) is a crucial regulator of carcinogenesis and therapeutic efficacy in ovarian cancer (OC). In this study, 593 OC patients from TCGA were divided into high and low score groups based on their immune/stromal scores resulting from analysis utilizing the ESTIMATE algorithm. Differential expression analysis revealed 294 intersecting genes that influencing both the immune and stromal scores. Further Cox regression analysis identified 34 differentially expressed genes (DEGs) as prognostic-related genes. Finally, the nine-gene signature was derived from the prognostic-related genes using a Least Absolute Shrinkage and Selection Operator (LASSO) and Cox regression. This nine-gene signature could effectively distinguish the high-risk patients in the training (TCGA database) and validation (GSE17260) cohorts (all p < 0.01). A time-dependent receiver operating characteristic (ROC) analysis showed that the nine-gene signature had a reasonable predictive accuracy (AUC = 0.707, AUC =0.696) in both cohorts. In addition, this nine-gene signature is associated with immune infiltration in TME by Gene Set Variation Analysis (GSVA), and can be used to predict the survival of patients with OC.

Proteolytic chemokine cleavage as a regulator of lymphocytic infiltration in solid tumors

In the past decade, immune-based therapies such as monoclonal antibodies against tumor epitopes or immune checkpoint inhibitors have become an integral part of contemporary cancer treatment in many entities. However, a fundamental prerequisite for the success of such therapies is a sufficient trafficking of tumor-infiltrating lymphocytes into the tumor microenvironment. This infiltration is facilitated by chemokines, a group of about 50 small proteins capable of chemotactically guiding leukocytes. Proteolytic inactivation of chemokines leading to an impaired infiltration of immune effector cells appears to be an efficient immune escape mechanism of solid cancers.

The CXCR3 and CX3CR1 chemokine receptor ligands CXCL9-11 and CX3CL1, respectively, are mainly responsible for the tumor-suppressive lymphocytic infiltration into the tumor micromilieu. Their structure explains the biochemical basis of their proteolytic cleavage, while in vivo data from mouse models and patient samples shed light on the corresponding processes in cancer. The emerging roles of proteases, e.g., matrix metalloproteinases, cathepsins, and dipeptidyl peptidase 4, in chemokine inactivation define new resistance mechanisms against immunotherapies and identify attractive new targets to enhance immune intervention in cancer.

C-C motif chemokine 14 as a novel potential biomarker for predicting the prognosis of epithelial ovarian cancer

Previous studies have demonstrated that C-C motif chemokine 14 (CCL14) plays an important role in the occurrence and development of cancer. However, the significance of CCL14 in the progression and prognosis of epithelial ovarian cancer (EOC) has not yet been reported. The standard EnVision procedure for tissue microarrays was used to evaluate the immunohistochemical expression of CCL14 protein in 154 patients with EOC who underwent tumor-debulking operations at the Central Cancer Department of Sun Yat-Sen University (Guangzhou, China) or Jiangmen Central Hospital (Jiangmen, China). The association between CCL14 expression and clinicopathological variables was assessed using the χ² test. For survival status of patients with EOC, Kaplan-Meier survival analysis and a Cox multivariate regression model was used. Expression of CCL14 protein was significantly associated with International Federation of Gynecology and Obstetric stage (P=0.014) and pN status(P=0.005). Kaplan-Meier survival analysis revealed that the survival time of patients with high expression of CCL14 was 136.1 months and that of patients with low expression of CCL14 was 98.9 months (P=0.026). Multivariate analysis demonstrated that CCL14 upregulation was associated with overall survival time (HR, 0.48; 95% CI, 0.261–0.896; P=0.021) and progression-free survival time (HR,0.437; 95% CI, 0.228–0.839; P=0.013). In conclusion, CCL14 is an independent prognostic factor for EOC and upregulation of CCL14 is associated with a more favorable prognosis in patients with EOC.

Prognostic and predictive values of CXCL10 in colorectal cancer

BACKGROUND

The role of CXCL10 in progression and prognosis of colorectal cancer (CRC) has been studied for years, yet results remain controversial.

AIM

This study aims to explore the relationship between CXCL10 and CRC progression and prognosis.

METHODS

We evaluated plasma CXCL10 in CRC patients using ELISA. We also performed a meta-analysis of the associations between CXCL10 and overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS), relapse-free survival (RFS), and clinicopathological features. Finally, correlations between CXCL10 and methylation or immune infiltration were performed using TCGA data.

RESULTS

ELISA analysis showed that CXCL10 was associated with age, red blood cells, blood platelets, and blood urea nitrogen. A separate analysis of 3,763 patients from 24 studies revealed that there were significant associations between low CXCL10 expression and OS (HR 1.25, 95% CI 1.01-1.53), DFS (HR 1.65, 95% CI 1.17-2.34), and RFS (HR 1.43, 95% CI 1.20-1.71) in CRC. Additionally, downregulated CXCL10 expression was significantly correlated with age [odds ratio (OR) 1.31, 95% CI 1.13-1.52], metastasis (OR 1.34, 95% CI 1.11-1.63), recurrence (OR 1.46, 95% CI 1.16-1.83), tumor location (OR 1.88, 95% CI 1.58-2.24), differentiation (OR 0.57, 95% CI 0.35-0.93), microsatellite instability (OR 0.23, 95% CI 0.15-0.35), BRAF mutation (OR 1.62, 95% CI 1.25-2.08), p53 mutation (OR 0.28, 95% CI 0.16-0.47), and CIMP (OR 0.27, 95% CI 0.17-0.43). Furthermore, significant associations were observed between CXCL10 and methylation and immune infiltration.

CONCLUSIONS

The study suggests that CXCL10 might be a potential target for the treatment of CRC.

TRIAL REGISTRATION

NCT03189992. Registered 4 June 2017, https://www.clinicaltrials.gov/ct2/show/study/NCT03189992?term=NCT03189992&rank=1 .

Generation of a Tumor-Specific Chemokine Gradient Using Oncolytic Vesicular Stomatitis Virus Encoding CXCL9

Genetically modified vesicular stomatitis virus (VSV) is an attractive agent for cancer treatment due to rapid intratumoral replication and observed clinical responses. Although VSV selectively kills malignant cells and can boost antitumor immunity, limited induction of intratumoral immune infiltration remains a barrier to efficacy in some cancer models. Here we engineered the oncolytic VSV platform to encode the T cell chemokine CXCL9, which is known to mediate the recruitment of activated CD8⁺ cytotoxic T cells and CD4⁺ T helper cells, and demonstrates conserved protein function between mice and humans. Chemotactic activity of the virally encoded chemokine was confirmed in vitro. Intratumoral concentration of CXCL9 was shown to increase after VSV therapy in three different cancer models, but to a much greater degree after VSV-CXCL9 therapy as compared with VSV control viruses. Despite a steep chemokine gradient from the tumor to the bloodstream, tumor trafficking of adoptively transferred and endogenous T cells was not measurably increased following VSV-CXCL9 therapy. Our results indicate that oncolytic VSV infection promotes release of CXCL9 in the tumor microenvironment, but further boosting of the functional chemokine gradient through virus engineering has little incremental impact on intratumoral immune cell infiltration in mouse and human tumor models.

Identification of Key Biomarkers and Potential Molecular Mechanisms in Oral Squamous Cell Carcinoma by Bioinformatics Analysis

The aim of this study was to explore the key genes, microRNA (miRNA), and the pathogenesis of oral squamous cell carcinoma (OSCC) at the molecular level through the analysis of bioinformatics, which could provide a theoretical basis for the screening of drug targets. Data of OSCC were obtained from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified via GEO2R analysis. Next, protein-protein interaction (PPI) network of DEGs was constructed through Search Tool for the Retrieval of Interacting Gene and visualized via Cytoscape, whereas the hub genes were screened out with Cytoscape. Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed by Database for Annotation, Visualization and Integrated Discovery. The miRNA, which might regulate hub genes, were screened out with TargetScan and GO and KEGG analysis of miRNA was performed by DNA Intelligent Analysis-miRPath. Survival analyses of DEGs were conducted via the Kaplan-Meier plotter. Finally, the relationships between gene products and tumors were analyzed by Comparative Toxicogenomics Database. A total of 121 differential genes were identified. One hundred thirty-five GO terms and 56 pathways were obtained, which were mainly related to PI3K-Akt signals pathway, FoxO signaling pathway, Wnt signaling pathway, cell cycle, p53 signaling pathway, cellular senescence, and other pathways; 10 genes were identified as hub genes through modules analyses in the PPI network. Finally, a survival analysis of 10 hub genes was conducted, which showed that the low expression of matrix metalloproteinase (MMP)1, MMP3, and C-X-C motif chemokine ligand (CXCL)1 and the high expression of CXCL9 and CXCL10 resulted in a significantly poor 5-year overall survival rate in patients with OSCC. In this study, the DEGs of OSCC was analyzed, which assists us in a systematic understanding of the pathogenicity underlying occurrence and development of OSCC. The MMP1, MMP3, CXCL1, CXCL9, and CXCL10 genes might be used as potential targets to improve diagnosis and as immunotherapy biomarkers for OSCC.

Poly(I:C)-Mediated Death of Human Prostate Cancer Cell Lines Is Induced by Interleukin-27 Treatment

Interleukin (IL)-27 is a promising anti-cancer cytokine with therapeutic potential. Exhibiting overlapping properties with type I and II interferons (IFNs), IL-27 impacts cancer cell viability and immune cell activity. Known to modulate toll-like receptor (TLR) expression, we investigated whether IL-27 affected TLR-mediated death in cancer cells. Using DU145 and PC3 cell lines as models of prostate cancer, we investigated whether IL-27 and IFN-γ affect TLR3-mediated cell death. Our results demonstrate that when IL-27 or IFN-γ is added with polyinosinic-polycytidylic acid [poly(I:C)], type I IFN (IFN-I) expression increases concurrently with cell death. IL-27 and IFN-γ enhanced TLR3 expression, suggesting a mechanism for sensitization to cell death. Further, PC3 cells were more sensitive to IL-27/poly(I:C)-induced cell death compared with DU145 cells. This correlated with higher production of IFN-β and inducible protein-10 versus IL-6 in response to treatment of PC3 cells compared with DU145. Taken together, this study demonstrates a potential role for IL-27 in the treatment of prostate cancer.

Functions of the CXC ligand family in the pancreatic tumor microenvironment

Therapeutic resistance is the major contributor to the poor prognosis of and low survival from pancreatic cancer (PC). Cancer progression is a complex process reliant on interactions between the tumor and the tumor microenvironment (TME). Members of the CXCL family of chemokines are present in the pancreatic TME and seem to play a vital role in regulating PC progression. As pancreatic tumors interact with the TME and with PC stem cells (CSCs), determining the roles of specific members of the CXCL family is vital to the development of improved therapies. This review highlights the roles of selected CXCLs in the interactions between pancreatic tumor and its stroma, and in CSC phenotypes, which can be used to identify potential treatment targets.

STING agonist therapy in combination with PD-1 immune checkpoint blockade enhances response to carboplatin chemotherapy in high-grade serous ovarian cancer

Background

High-grade serous carcinoma (HGSC) of the ovary is predominantly diagnosed at late stages and primarily treated with debulking surgery followed by platinum/taxane-based chemotherapy. Although certain patients benefit significantly from currently used chemotherapy, there are patients who either do not respond or have an inadequate duration of response. We previously showed that tumours from chemoresistant patients have an immunosuppressed pre-existing tumour immune microenvironment with decreased expression of Type I Interferon (IFN1) genes.

Methods

Efficacy of a ‘STimulator of INterferon Genes’ agonist was evaluated in combination with carboplatin chemotherapy and PD-1 immune checkpoint blockade therapy in the ID8-Trp53^−/− immunocompetent murine model of HGSC.

Results

Treatment with STING agonist led to decreased ascites accumulation and decreased tumour burden. Survival of mice treated with a combination of carboplatin, STING agonist and anti-PD-1 antibody was the longest. Tumour immune transcriptomic profiling revealed higher IFN response, antigen presentation and MHC II genes in tumours from STING agonist-treated mice compared to vehicle controls. Flow cytometry analysis revealed significantly higher intra-tumoural PD-1⁺ and CD69⁺CD62L⁻, CD8⁺ T cells in STING agonist-treated mice.

Conclusions

These findings will enable rational design of clinical trials aimed at combinatorial approaches to improve chemotherapy response and survival in HGSC patients.

Improved migration of tumor ascites lymphocytes to ovarian cancer microenvironment by CXCR2 transduction

Chemokines are essential mediators of cellular trafficking, interactions and tumor development. Though adoptive cell therapy (ACT) has been a tremendous success in the treatment of metastatic melanoma (MM), a major obstacle for successful ACT, is limited homing of effector T cells to immune suppressive tumor sites. We hypothesized that equipping T cells with chemokine receptors matching the chemokines of the tumor microenvironment, could improve tumor homing of T cells. T cells from malignant ascites (n = 13); blood from ovarian cancer (OC) patients (n = 14); and healthy donors (n = 13) were analyzed by flow cytometry. We found that FoxP3⁺ regulatory T cells accumulation in patients with OC associates with CCR4 expression. We characterized a chemokine profile of ascites chemokines, and expression of corresponding receptors on circulating T cells and tumor ascites lymphocytes (TALs). CCL22, CXCL9, CXCL10 and CXCL12 associated with enrichment of CCR4⁺, CCR5⁺, CXCR3⁺ and CXCR4⁺ T cells in ascites. Circulating T cells and TALs however did not express CXCR2, identifying CXCR2 as candidate for chemokine receptor transduction. TALs readily expressed IFNγ and TNFα upon stimulation despite the frequency decreasing with in vitro expansion. Lentiviral transduction of TALs (n = 4) with chemokine receptor CXCR2 significantly increased transwell migration of TALs towards rhIL8 and autologous ascites. The majority of expanded and transduced TALs were of a T effector memory subtype. This proof of concept study shows that chemokine receptor engineering with CXCR2 is feasible and improves homing of transduced TALs towards the OC microenvironment.

Interleukin-33 modulates inflammation in endometriosis

Endometriosis is a debilitating condition that is categorized by the abnormal growth of endometrial tissue outside the uterus. Although the pathogenesis of this disease remains unknown, it is well established that endometriosis patients exhibit immune dysfunction. Interleukin (IL)-33 is a danger signal that is a critical regulator of chronic inflammation. Although plasma and peritoneal fluid levels of IL-33 have been associated with deep infiltrating endometriosis, its contribution to the disease pathophysiology is unknown. We investigated the role of IL-33 in the pathology of endometriosis using patient samples, cell lines and a syngeneic mouse model. We found that endometriotic lesions produce significantly higher levels of IL-33 compared to the endometrium of healthy, fertile controls. In vitro stimulation of endometrial epithelial, endothelial and endometriotic epithelial cells with IL-33 led to the production of pro-inflammatory and angiogenic cytokines. In a syngeneic mouse model of endometriosis, IL-33 injections caused systemic inflammation, which manifested as an increase in plasma pro-inflammatory cytokines compared to control mice. Furthermore, endometriotic lesions from IL-33 treated mice were highly vascularized and exhibited increased proliferation. Collectively, we provide convincing evidence that IL-33 perpetuates inflammation, angiogenesis and lesion proliferation, which are critical events in the lesion survival and progression of endometriosis.

Epigenetic therapy activates type I interferon signaling in murine ovarian cancer to reduce immunosuppression and tumor burden

Ovarian cancer is the most lethal of all gynecological cancers, and there is an urgent unmet need to develop new therapies. Epithelial ovarian cancer (EOC) is characterized by an immune suppressive microenvironment, and response of ovarian cancers to immune therapies has thus far been disappointing. We now find, in a mouse model of EOC, that clinically relevant doses of DNA methyltransferase and histone deacetylase inhibitors (DNMTi and HDACi, respectively) reduce the immune suppressive microenvironment through type I IFN signaling and improve response to immune checkpoint therapy. These data indicate that the type I IFN response is required for effective in vivo antitumorigenic actions of the DNMTi 5-azacytidine (AZA). Through type I IFN signaling, AZA increases the numbers of CD45⁺ immune cells and the percentage of active CD8⁺ T and natural killer (NK) cells in the tumor microenvironment, while reducing tumor burden and extending survival. AZA also increases viral defense gene expression in both tumor and immune cells, and reduces the percentage of macrophages and myeloid-derived suppressor cells in the tumor microenvironment. The addition of an HDACi to AZA enhances the modulation of the immune microenvironment, specifically increasing T and NK cell activation and reducing macrophages over AZA treatment alone, while further increasing the survival of the mice. Finally, a triple combination of DNMTi/HDACi plus the immune checkpoint inhibitor α-PD-1 provides the best antitumor effect and longest overall survival, and may be an attractive candidate for future clinical trials in ovarian cancer.