Anti-tumorigenic effects of Type 1 interferon are subdued by integrated stress responses

Multifaceted role of GCN2 in tumor adaptation and therapeutic targeting

Tumor cells voraciously consume nutrients from their environment to facilitate rapid proliferation, necessitating effective strategies to manage nutrient scarcity during tumor growth and progression. A pivotal regulatory mechanism in this context is the Integrated Stress Response (ISR), which ensures cellular homeostasis under conditions such as endoplasmic reticulum stress, the unfolded protein response, and nutrient deprivation. Within the ISR framework, the kinase GCN2 is critical, orchestrating a myriad of cellular processes including the inhibition of protein synthesis, the enhancement of amino acid transport, autophagy initiation, and angiogenesis. These processes collectively enable tumor survival and adaptation under nutrient-limited conditions. Furthermore, GCN2-mediated pathways may induce apoptosis, a property exploited by specific therapeutic agents. Leveraging extensive datasets from TCGA, GEO, and GTEx projects, we conducted a pan-cancer analysis to investigate the prognostic significance of GCN2 expression across diverse cancer types. Our analysis indicates that GCN2 expression significantly varies and correlates with both adverse and favorable prognoses depending on the type of cancer, illustrating its complex role in tumorigenesis. Importantly, GCN2 also modulates the tumor immune microenvironment, influencing immune checkpoint expression and the functionality of immune cells, thereby affecting immunotherapy outcomes. This study highlights the potential of targeting GCN2 with specific inhibitors, as evidenced by their efficacy in preclinical models to augment treatment responses and combat resistance in oncology. These findings advocate for a deeper exploration of GCN2's multifaceted roles, which could pave the way for novel targeted therapies in cancer treatment, aiming to improve clinical outcomes.

Endoplasmic reticulum stress in diseases

The endoplasmic reticulum (ER) is a key organelle in eukaryotic cells, responsible for a wide range of vital functions, including the modification, folding, and trafficking of proteins, as well as the biosynthesis of lipids and the maintenance of intracellular calcium homeostasis. A variety of factors can disrupt the function of the ER, leading to the aggregation of unfolded and misfolded proteins within its confines and the induction of ER stress. A conserved cascade of signaling events known as the unfolded protein response (UPR) has evolved to relieve the burden within the ER and restore ER homeostasis. However, these processes can culminate in cell death while ER stress is sustained over an extended period and at elevated levels. This review summarizes the potential role of ER stress and the UPR in determining cell fate and function in various diseases, including cardiovascular diseases, neurodegenerative diseases, metabolic diseases, autoimmune diseases, fibrotic diseases, viral infections, and cancer. It also puts forward that the manipulation of this intricate signaling pathway may represent a novel target for drug discovery and innovative therapeutic strategies in the context of human diseases.

Adjuvant COX inhibition augments STING signaling and cytolytic T cell infiltration in irradiated 4T1 tumors

Immune therapy is the new frontier of cancer treatment. Therapeutic radiation is a known inducer of immune response and can be limited by immunosuppressive mediators including cyclooxygenase-2 (COX2) that is highly expressed in aggressive triple negative breast cancer (TNBC). A clinical cohort of TNBC tumors revealed poor radiation therapeutic efficacy in tumors expressing high COX2. Herein, we show that radiation combined with adjuvant NSAID (indomethacin) treatment provides a powerful combination to reduce both primary tumor growth and lung metastasis in aggressive 4T1 TNBC tumors, which occurs in part through increased antitumor immune response. Spatial immunological changes including augmented lymphoid infiltration into the tumor epithelium and locally increased cGAS/STING1 and type I IFN gene expression were observed in radiation-indomethacin-treated 4T1 tumors. Thus, radiation and adjuvant NSAID treatment shifts "immune desert phenotypes" toward antitumor M1/TH1 immune mediators in these immunologically challenging tumors. Importantly, radiation-indomethacin combination treatment improved local control of the primary lesion, reduced metastatic burden, and increased median survival when compared with radiation treatment alone. These results show that clinically available NSAIDs can improve radiation therapeutic efficacy through increased antitumor immune response and augmented local generation of cGAS/STING1 and type I IFNs.

Targeting hnRNPC suppresses thyroid follicular epithelial cell apoptosis and necroptosis through m6A-modified ATF4 in autoimmune thyroid disease

Both environmental and genetic factors contribute to the etiology of autoimmune thyroid disease (AITD) including Graves' disease (GD) and Hashimoto's thyroiditis (HT). However, the exact pathogenesis and interactions that occur between environmental factors and genes remain unclear, and therapeutic targets require further investigation due to limited therapeutic options. To solve such problems, this study utilized single-cell transcriptome, whole transcriptome, full-length transcriptome (Oxford nanopore technology), and metabolome sequencing to examine thyroid lesion tissues from 2 HT patients and 2 GD patients as well as healthy thyroid tissue from 1 control subject. HT patients had increased ATF4-positive thyroid follicular epithelial (ThyFoEp) cells, which significantly increased endoplasmic reticulum stress. The enhanced sustained stress resulted in cell death mainly including apoptosis and necroptosis. The ATF4-based global gene regulatory network and experimental validation revealed that N6-methyladenosine (m6A) reader hnRNPC promoted the transcriptional activity, synthesis, and translation of ATF4 through mediating m6A modification of ATF4. Increased ATF4 expression initiated endoplasmic reticulum stress signaling, which when sustained, caused apoptosis and necroptosis in ThyFoEp cells, and mediated HT development. Targeting hnRNPC and ATF4 notably decreased ThyFoEp cell death, thus ameliorating disease progression. Collectively, this study reveals the mechanisms by which microenvironmental cells in HT and GD patients trigger and amplify the thyroid autoimmune cascade response. Furthermore, we identify new therapeutic targets for the treatment of autoimmune thyroid disease, hoping to provide a potential way for targeted therapy.

Clinical Application of Small Extracellular Vesicles in Gynecologic Malignancy Treatments

Small extracellular vesicles (sEVs) are the key mediators of intercellular communication. They have the potential for clinical use as diagnostic or therapeutic biomarkers and have been explored as vectors for drug delivery. Identification of reliable and noninvasive biomarkers, such as sEVs, is important for early diagnosis and precise treatment of gynecologic diseases to improve patient prognosis. Previous reviews have summarized routine sEVs isolation and identification methods; however, novel and unconventional methods have not been comprehensively described. This review summarizes a convenient method of isolating sEVs from body fluids and liquid biopsy-related sEV markers for early, minimally invasive diagnosis of gynecologic diseases. In addition, the characteristics of sEVs as drug carriers and in precision treatment and drug resistance are introduced, providing a strong foundation for identifying novel and potential therapeutic targets for sEV therapy. We propose potential directions for further research on the applications of sEVs in the diagnosis and treatment of gynecologic diseases.

Tumor-Suppressive and Immune-Stimulating Roles of Cholesterol 25-hydroxylase in Pancreatic Cancer Cells

Cholesterol dependence is an essential characteristic of pancreatic ductal adenocarcinoma (PDAC). Cholesterol 25-hydroxylase (CH25H) catalyzes monooxygenation of cholesterol into 25-hydroxycholesterol, which is implicated in inhibiting cholesterol biosynthesis and in cholesterol depletion. Here, we show that, within PDAC cells, accumulation of cholesterol was facilitated by the loss of CH25H. Methylation of the CH25H gene and decreased levels of CH25H expression occurred in human pancreatic cancers and was associated with poor prognosis. Knockout of Ch25h in mice accelerated progression of Kras-driven pancreatic intraepithelial neoplasia. Conversely, restoration of CH25H expression in human and mouse PDAC cells decreased their viability under conditions of cholesterol deficit, and decelerated tumor growth in immune competent hosts. Mechanistically, the loss of CH25H promoted autophagy resulting in downregulation of MHC-I and decreased CD8+ T-cell tumor infiltration. Re-expression of CH25H in PDAC cells combined with immune checkpoint inhibitors notably inhibited tumor growth. We discuss additional benefits that PDAC cells might gain from inactivation of CH25H and the potential translational importance of these findings for therapeutic approaches to PDAC.

IMPLICATIONS

Loss of CH25H by pancreatic cancer cells may stimulate tumor progression and interfere with immunotherapies.

Major roles of the circadian clock in cancer

Circadian rhythms are natural rhythms that widely exist in all creatures, and regulate the processes and physiological functions of various biochemical reactions. The circadian clock is critical for cancer occurrence and progression. Its function is regulated by metabolic activities, and the expression and transcription of various genes. This review summarizes the composition of the circadian clock; the biological basis for its function; its relationship with, and mechanisms in, cancer; its various functions in different cancers; the effects of anti-tumor treatment; and potential therapeutic targets. Research in this area is expected to advance understanding of circadian locomotor output cycles kaput (CLOCK) and brain and muscle ARNT-like protein 1 (BMAL1) in tumor diseases, and contribute to the development of new anti-tumor treatment strategies.

Protection of Regulatory T Cells from Fragility and Inactivation in the Tumor Microenvironment

Fragility of regulatory T (Treg) cells manifested by the loss of neuropilin-1 (NRP1) and expression of IFNγ undermines the immune suppressive functions of Treg cells and contributes to the success of immune therapies against cancers. Intratumoral Treg cells somehow avoid fragility; however, the mechanisms by which Treg cells are protected from fragility in the tumor microenvironment are not well understood. Here, we demonstrate that the IFNAR1 chain of the type I IFN (IFN1) receptor was downregulated on intratumoral Treg cells. Downregulation of IFNAR1 mediated by p38α kinase protected Treg cells from fragility and maintained NRP1 levels, which were decreased in response to IFN1. Genetic or pharmacologic inactivation of p38α and stabilization of IFNAR1 in Treg cells induced fragility and inhibited their immune suppressive and protumorigenic activities. The inhibitor of sumoylation TAK981 (Subasumstat) upregulated IFNAR1, eliciting Treg fragility and inhibiting tumor growth in an IFNAR1-dependent manner. These findings describe a mechanism by which intratumoral Treg cells retain immunosuppressive activities and suggest therapeutic approaches for inducing Treg fragility and increasing the efficacy of immunotherapies.

Decoding endoplasmic reticulum stress signals in cancer cells and antitumor immunity

The tumor microenvironment (TME) provokes endoplasmic reticulum (ER) stress in malignant cells and infiltrating immune populations. Sensing and responding to ER stress is coordinated by the unfolded protein response (UPR), an integrated signaling pathway governed by three ER stress sensors: activating transcription factor (ATF6), inositol-requiring enzyme 1α (IRE1α), and protein kinase R (PKR)-like ER kinase (PERK). Persistent UPR activation modulates malignant progression, tumor growth, metastasis, and protective antitumor immunity. Hence, therapies targeting ER stress signaling can be harnessed to elicit direct tumor killing and concomitant anticancer immunity. We highlight recent findings on the role of the ER stress responses in onco-immunology, with an emphasis on genetic vulnerabilities that render tumors highly sensitive to therapeutic UPR modulation.

Direct and indirect effects of IFN-α2b in malignancy treatment: not only an archer but also an arrow

Interferon-α2b (IFN-α2b) is a highly active cytokine that belongs to the interferon-α (IFN-α) family. IFN-α2b has beneficial antiviral, antitumour, antiparasitic and immunomodulatory activities. Direct and indirect antiproliferative effects of IFN-α2b have been found to occur via multiple pathways, mainly the JAK-STAT pathway, in certain cancers. This article reviews mechanistic studies and clinical trials on IFN-α2b. Potential regulators of the function of IFN-α2b were also reviewed, which could be utilized to relieve the poor response to IFN-α2b. IFN-α2b can function not only by enhancing the systematic immune response but also by directly killing tumour cells. Different parts of JAK-STAT pathway activated by IFN-α2b, such as interferon alpha and beta receptors (IFNARs), Janus kinases (JAKs) and IFN‐stimulated gene factor 3 (ISGF3), might serve as potential target for enhancing the pharmacological action of IFN-α2b. Despite some issues that remain to be solved, based on current evidence, IFN-α2b can inhibit disease progression and improve the survival of patients with certain types of malignant tumours. More efforts should be made to address potential adverse effects and complications.

Targeting PARP11 to avert immunosuppression and improve CAR T therapy in solid tumors

Evasion of antitumor immunity and resistance to therapies in solid tumors are aided by an immunosuppressive tumor microenvironment (TME). We found that TME factors, such as regulatory T cells and adenosine, downregulated type I interferon receptor IFNAR1 on CD8⁺ cytotoxic T lymphocytes (CTLs). These events relied upon poly-ADP ribose polymerase-11 (PARP11), which was induced in intratumoral CTLs and acted as a key regulator of the immunosuppressive TME. Ablation of PARP11 prevented loss of IFNAR1, increased CTL tumoricidal activity and inhibited tumor growth in an IFNAR1-dependent manner. Accordingly, genetic or pharmacologic inactivation of PARP11 augmented the therapeutic benefits of chimeric antigen receptor T cells. Chimeric antigen receptor CTLs engineered to inactivate PARP11 demonstrated a superior efficacy against solid tumors. These findings highlight the role of PARP11 in the immunosuppressive TME and provide a proof of principle for targeting this pathway to optimize immune therapies.

The Comprehensive Analysis of Interferon-Related Prognostic Signature with regard to Immune Features in Ovarian Cancer

Interferon plays an important role in immune response of ovarian cancer. However, the expression pattern of interferon in ovarian cancer remains unclear. This study is aimed at exploring the expression profile of interferon-relate genes and constructing an interferon-based prognostic signature in ovarian cancer. The ovarian cancer samples collected from TCGA database were viewed as the training set, and ovarian cancer samples collected from GEO datasets were used as the independent validation sets. Univariate Cox regression analysis and multivariate Cox regression analysis were used to construct interferon-related signature, which worked as independent prognostic factor. Bioinformatics based on David software, GSEA, and R software were used to investigate the relationship between immune status and the signature in ovarian cancer. The signature showed close correlation with the status for ovarian cancer immune microenvironment, which might provide the possibility for clinical targeted therapy.

A small-molecule SUMOylation inhibitor activates antitumor immune responses and potentiates immune therapies in preclinical models

[Figure: see text].

The Yin and Yang of Type I IFNs in Cancer Promotion and Immune Activation

Type I Interferons (IFNs) are key regulators of natural and therapy-induced host defense against viral infection and cancer. Several years of remarkable progress in the field of oncoimmunology have revealed the dual nature of these cytokines. Hence, Type I IFNs may trigger anti-tumoral responses, while leading immune dysfunction and disease progression. This dichotomy relies on the duration and intensity of the transduced signaling, the nature of the unleashed IFN stimulated genes, and the subset of responding cells. Here, we discuss the role of Type I IFNs in the evolving relationship between the host immune system and cancer, as we offer a view of the therapeutic strategies that exploit and require an intact Type I IFN signaling, and the role of these cytokines in inducing adaptive resistance. A deep understanding of the complex, yet highly regulated, network of Type I IFN triggered molecular pathways will help find a timely and immune"logical" way to exploit these cytokines for anticancer therapy.

Down-Regulation of ID2-AS1 Alleviates the Neuronal Injury Induced by 1-Methy1-4-Phenylpyridinium in Human Neuroblastoma Cell Line SH-SY5Y Cells Through Regulating miR-199a-5p/IFNAR1/JAK2/STAT1 Axis

We aimed to illustrate the roles and molecular mechanisms of ID2-AS1 in parkinson's disease (PD). Methods: qRT-PCR detected the expression of ID2-AS1. CCK-8, LDH release assays the effect of ID2-AS1 knockdown on PD cells. Flow cytometry and Western Blot were used to detect the effect of ID2-AS1 inhibition on PD cell apoptosis. ELISA analysis showed that ID2-AS1 inhibition can reduce the inflammation of PD cells. ROS activity assay showed that inhibiting ID2-AS1 attenuated the oxidative stress induced by 1-methy1-4-phenylpyridinium (MPP+). RNA binding protein immunoprecipitation assay showed that ID2-AS1 is mainly located in the cytoplasm. The luciferase reporter assay is used to verify the interaction. In our study, ID2-AS1 was concentration-dependently and time-dependently up-regulated in MPP+ -treated human neuroblastoma cell line SH-SY5Y. ID2-AS1 knockdown enhanced cell proliferation and decreased cell death in PD cells. Knockdown of ID2-AS1 attenuates MPP+ -induced cytotoxicity in SH-SY5Y cells. ID2-AS1 is a sponge of miR-199a-5p. IFNAR1 is a target of miR-199a-5p. Inhibition of miR-199a-5p and overexpression of IFNAR1 alleviate the inhibitory effect of ID2-AS1 knockdown on MPP+ triggered neuronal injury. Inhibition of miR-199a-5p and overexpression of IFNAR1 alleviate the inhibitory effect of ID2-AS1 knockdown on MPP+ -triggered JAK2/STAT1 activation. Overall, down-regulation of ID2-AS1 alleviated the neuronal injury in PD through regulating miR-199a-5p/IFNAR1/JAK2/STAT1 axis.

Regulation of intercellular biomolecule transfer-driven tumor angiogenesis and responses to anticancer therapies

Intercellular biomolecule transfer (ICBT) between malignant and benign cells is a major driver of tumor growth, resistance to anticancer therapies, and therapy-triggered metastatic disease. Here we characterized cholesterol 25-hydroxylase (CH25H) as a key genetic suppressor of ICBT between malignant and endothelial cells (ECs) and of ICBT-driven angiopoietin-2-dependent activation of ECs, stimulation of intratumoral angiogenesis, and tumor growth. Human CH25H was downregulated in the ECs from patients with colorectal cancer and the low levels of stromal CH25H were associated with a poor disease outcome. Knockout of endothelial CH25H stimulated angiogenesis and tumor growth in mice. Pharmacologic inhibition of ICBT by reserpine compensated for CH25H loss, elicited angiostatic effects (alone or combined with sunitinib), augmented the therapeutic effect of radio-/chemotherapy, and prevented metastatic disease induced by these regimens. We propose inhibiting ICBT to improve the overall efficacy of anticancer therapies and limit their prometastatic side effects.

Immune suppressive activity of myeloid-derived suppressor cells in cancer requires inactivation of the type I interferon pathway

Myeloid-derived suppressor cells (MDSC) are pathologically activated neutrophils and monocytes with potent immune suppressive activity. These cells play an important role in accelerating tumor progression and undermining the efficacy of anti-cancer therapies. The natural mechanisms limiting MDSC activity are not well understood. Here, we present evidence that type I interferons (IFN1) receptor signaling serves as a universal mechanism that restricts acquisition of suppressive activity by these cells. Downregulation of the IFNAR1 chain of this receptor is found in MDSC from cancer patients and mouse tumor models. The decrease in IFNAR1 depends on the activation of the p38 protein kinase and is required for activation of the immune suppressive phenotype. Whereas deletion of IFNAR1 is not sufficient to convert neutrophils and monocytes to MDSC, genetic stabilization of IFNAR1 in tumor bearing mice undermines suppressive activity of MDSC and has potent antitumor effect. Stabilizing IFNAR1 using inhibitor of p38 combined with the interferon induction therapy elicits a robust anti-tumor effect. Thus, negative regulatory mechanisms of MDSC function can be exploited therapeutically.

Type I and II Interferons in the Anti-Tumor Immune Response

The interferons (IFNs) are essential components of the immune response against infections and malignancies. IFNs are potent promoters of the anti-tumor response, but there is also evidence that feedback mechanisms regulated by IFNs negatively control immune responses to avoid hyper-activation and limit inflammation. This balance of responses plays an important role in cancer surveillance, immunoediting and response to anticancer therapeutic approaches. Here we review the roles of both type I and type II IFNs on the control of the immune response against malignancies in the context of effects on both malignant cells and cells of the immune system in the tumor microenvironment.

Endoplasmic reticulum stress signals in the tumour and its microenvironment

Protein handling, modification and folding in the endoplasmic reticulum (ER) are tightly regulated processes that determine cell function, fate and survival. In several tumour types, diverse oncogenic, transcriptional and metabolic abnormalities cooperate to generate hostile microenvironments that disrupt ER homeostasis in malignant and stromal cells, as well as infiltrating leukocytes. These changes provoke a state of persistent ER stress that has been demonstrated to govern multiple pro-tumoural attributes in the cancer cell while dynamically reprogramming the function of innate and adaptive immune cells. Aberrant activation of ER stress sensors and their downstream signalling pathways have therefore emerged as key regulators of tumour growth and metastasis as well as response to chemotherapy, targeted therapies and immunotherapy. In this Review, we discuss the physiological inducers of ER stress in the tumour milieu, the interplay between oncogenic signalling and ER stress response pathways in the cancer cell and the profound immunomodulatory effects of sustained ER stress responses in tumours.

Modulation of Early Host Innate Immune Response by an Avipox Vaccine Virus' Lateral Body Protein

The avian pathogen fowlpox virus (FWPV) has been successfully used as a vaccine vector in poultry and humans, but relatively little is known about its ability to modulate host antiviral immune responses in these hosts, which are replication-permissive and nonpermissive, respectively. FWPV is highly resistant to avian type I interferon (IFN) and able to completely block the host IFN-response. Microarray screening of host IFN-regulated gene expression in cells infected with 59 different, nonessential FWPV gene knockout mutants revealed that FPV184 confers immunomodulatory capacity. We report that the FPV184-knockout virus (FWPVΔ184) induces the cellular IFN response as early as 2 h postinfection. The wild-type, uninduced phenotype can be rescued by transient expression of FPV184 in FWPVΔ184-infected cells. Ectopic expression of FPV184 inhibited polyI:C activation of the chicken IFN-β promoter and IFN-α activation of the chicken Mx1 promoter. Confocal and correlative super-resolution light and electron microscopy demonstrated that FPV184 has a functional nuclear localisation signal domain and is packaged in the lateral bodies of the virions. Taken together, these results provide a paradigm for a late poxvirus structural protein packaged in the lateral bodies, capable of suppressing IFN induction early during the next round of infection.

The Unfolded Protein Response Mediator PERK Governs Myeloid Cell-Driven Immunosuppression in Tumors through Inhibition of STING Signaling

The primary mechanisms supporting immunoregulatory polarization of myeloid cells upon infiltration into tumors remain largely unexplored. Elucidation of these signals could enable better strategies to restore protective anti-tumor immunity. Here, we investigated the role of the intrinsic activation of the PKR-like endoplasmic reticulum (ER) kinase (PERK) in the immunoinhibitory actions of tumor-associated myeloid-derived suppressor cells (tumor-MDSCs). PERK signaling increased in tumor-MDSCs, and its deletion transformed MDSCs into myeloid cells that activated CD8⁺ T cell-mediated immunity against cancer. Tumor-MDSCs lacking PERK exhibited disrupted NRF2-driven antioxidant capacity and impaired mitochondrial respiratory homeostasis. Moreover, reduced NRF2 signaling in PERK-deficient MDSCs elicited cytosolic mitochondrial DNA elevation and, consequently, STING-dependent expression of anti-tumor type I interferon. Reactivation of NRF2 signaling, conditional deletion of STING, or blockade of type I interferon receptor I restored the immunoinhibitory potential of PERK-ablated MDSCs. Our findings demonstrate the pivotal role of PERK in tumor-MDSC functionality and unveil strategies to reprogram immunosuppressive myelopoiesis in tumors to boost cancer immunotherapy.

Malignant cell-specific pro-tumorigenic role of type I interferon receptor in breast cancers

Within the microenvironment of solid tumors, stress associated with deficit of nutrients and oxygen as well as tumor-derived factors triggers the phosphorylation-dependent degradation of the IFNAR1 chain of type I interferon (IFN1) receptor and ensuing suppression of the IFN1 pathway. Here we sought to examine the importance of these events in malignant mammary cells. Expression of non-degradable IFNAR1^S526A mutant in mouse mammary adenocarcinoma cells stimulated the IFN1 pathway yet did not affect growth of these cells in vitro or ability to form subcutaneous tumors in the syngeneic mice. Remarkably, these cells exhibited a notably accelerated growth when transplanted orthotopically into mammary glands. Importantly, in human patients with either ER+ or ER- breast cancers, high levels of IFNAR1 were associated with poor prognosis. We discuss the putative mechanisms underlying the pro-tumorigenic role of IFNAR1 in malignant breast cells.

Rs11655237 polymorphism of LINC00673 affects the prognosis of cervical cancer by interfering with the interaction between LINC00673 and microRNA-1231

Single-nucleotide polymorphism (SNP) in long noncoding RNAs (lncRNAs) is known to disrupt the binding between lncRNAs and microRNAs. In this paper, we aimed to explore the role of LINC00673 rs11655237 SNP in the survival of cervical cancer (CC). Real-time polymerase chain reaction and western-blot analysis were used to detect expressions of LINC00673 and microRNA-1231 (miR-1231) in CC patients with different rs11655237 SNP genotypes. And the expression of LINC00673, miR-1231, and IFNAR1 was measured in mice and cells treated with exosomes carrying GG, GA, and AA rs11655237 genotypes. Compared with patients carrying the rs11655237 A allele of LINC00673 rs11655237 SNP, patients carrying the G allele showed higher overall survival and higher miR-1231 expression. In addition, the expression of miR-1231 was the highest in patients carrying the GG genotype and the lowest in patients carrying the AA genotype. Furthermore, the exosomes carrying GG, GA, and AA genotypes of LINC00673 rs11655237 SNP reduced tumor growth in mice, while the inhibitory effect of rs11655237 A allele was much stronger than that of the rs11655237 G allele. Additionally, exosome treatment upregulated the expression of LINC000673 and IFNAR1 while downregulating the expression of miR-1231. Interestingly, the A allele of rs11655237 generated a binding site for miR-1231 and subsequently affected the expression of IFNAR1, a target gene of miR-1231 containing a miR-1231 binding site in its 3'-untranslated region. Cells transfected with exosomes carrying GG, GA, and AA genotypes of LINC00673 rs11655237 SNP achieved higher LINC000673 and IFNAR1 expression along with lower miR-1231 expression. Therefore, rs11655237 can be used as a prognostic biomarker for CC.

An optimized retinoic acid-inducible gene I agonist M8 induces immunogenic cell death markers in human cancer cells and dendritic cell activation

RIG-I is a cytosolic RNA sensor that recognizes short 5' triphosphate RNA, commonly generated during virus infection. Upon activation, RIG-I initiates antiviral immunity, and in some circumstances, induces cell death. Because of this dual capacity, RIG-I has emerged as a promising target for cancer immunotherapy. Previously, a sequence-optimized RIG-I agonist (termed M8) was generated and shown to stimulate a robust immune response capable of blocking viral infection and to function as an adjuvant in vaccination strategies. Here, we investigated the potential of M8 as an anti-cancer agent by analyzing its ability to induce cell death and activate the immune response. In multiple cancer cell lines, M8 treatment strongly activated caspase 3-dependent apoptosis, that relied on an intrinsic NOXA and PUMA-driven pathway that was dependent on IFN-I signaling. Additionally, cell death induced by M8 was characterized by the expression of markers of immunogenic cell death-related damage-associated molecular patterns (ICD-DAMP)-calreticulin, HMGB1 and ATP-and high levels of ICD-related cytokines CXCL10, IFNβ, CCL2 and CXCL1. Moreover, M8 increased the levels of HLA-ABC expression on the tumor cell surface, as well as up-regulation of genes involved in antigen processing and presentation. M8 induction of the RIG-I pathway in cancer cells favored dendritic cell phagocytosis and induction of co-stimulatory molecules CD80 and CD86, together with increased expression of IL12 and CXCL10. Altogether, these results highlight the potential of M8 in cancer immunotherapy, with the capacity to induce ICD-DAMP on tumor cells and activate immunostimulatory signals that synergize with current therapies.

Type I interferons and dendritic cells in cancer immunotherapy

Type I interferons (IFNs) facilitate cancer immunosurveillance, antitumor immunity and antitumor efficacy of conventional cell death-inducing therapies (chemotherapy/radiotherapy) as well as immunotherapy. Moreover, it is clear that dendritic cells (DCs) play a significant role in aiding type I IFN-driven immunity. Owing to these antitumor properties several immunotherapies involving, or inducing, type I IFNs have received considerable clinical attention, e.g., recombinant IFNα2 or agonists targeting pattern recognition receptor (PRR) pathways like Toll-like receptors (TLRs), cGAS-STING or RIG-I/MDA5/MAVS. A series of preclinical and clinical evidence concurs that the success of anticancer therapy hinges on responsiveness of both cancer cells and DCs to type I IFNs. In this article, we discuss this link between type I IFNs and DCs in the context of cancer biology, with particular attention to mechanisms behind type I IFN production, their impact on DC driven anticancer immunity, and the implications of this for cancer immunotherapy, including DC-based vaccines.

The PKR-Like Endoplasmic Reticulum Kinase Promotes the Dissemination of Myc-Induced Leukemic Cells

Hyperactive oncogenic Myc stimulates protein synthesis that induces the unfolded protein response, which requires the function of the eukaryotic translation initiation factor 2-alpha kinase 3, also known as protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK). Activated PERK acts to limit mRNA translation, enable proper protein folding, and restore the homeostasis in the endoplasmic reticulum. Given that Myc activation contributes to many types of lymphoid and myeloid human leukemias, we used a mouse model to examine the importance of PERK in development and progression of Myc-induced leukemias. We found that genetic ablation of Perk does not suppress the generation of the leukemic cells in the bone marrow. However, the cell-autonomous Perk deficiency restricts the dissemination of leukemic cells into peripheral blood, lymph nodes, and vital peripheral organs. Whereas the loss of the IFNAR1 chain of type I IFN receptor stimulated leukemia, Perk ablation did not stabilize IFNAR1, suggesting that PERK stimulates the leukemic cells' dissemination in an IFNAR1-independent manner. We discuss the rationale for using PERK inhibitors against Myc-driven leukemias. IMPLICATIONS: The role of PERK in dissemination of Myc-induced leukemic cells demonstrated in this study argues for the use of PERK inhibitors against leukemia progression.

Ubiquitin Ligases in Cancer Immunotherapy - Balancing Antitumor and Autoimmunity

Considerable progress has been made in understanding the contribution of E3 ubiquitin ligases to health and disease, including the pathogenesis of immunological disorders. Ubiquitin ligases exert exquisite spatial and temporal control over protein stability and function, and are thus crucial for the regulation of both innate and adaptive immunity. Given that immune responses can be both detrimental (autoimmunity) and beneficial (antitumor immunity), it is vital to understand how ubiquitin ligases maintain immunological homeostasis. Such knowledge could reveal novel mechanisms underlying immune regulation and identify new therapeutic approaches to enhance antitumor immunity and safeguard against autoimmunity.

An Interferon-Driven Oxysterol-Based Defense against Tumor-Derived Extracellular Vesicles

Tumor-derived extracellular vesicles (TEV) "educate" healthy cells to promote metastases. We found that melanoma TEV downregulated type I interferon (IFN) receptor and expression of IFN-inducible cholesterol 25-hydroxylase (CH25H). CH25H produces 25-hydroxycholesterol, which inhibited TEV uptake. Low CH25H levels in leukocytes from melanoma patients correlated with poor prognosis. Mice incapable of downregulating the IFN receptor and Ch25h were resistant to TEV uptake, TEV-induced pre-metastatic niche, and melanoma lung metastases; however, ablation of Ch25h reversed these phenotypes. An anti-hypertensive drug, reserpine, suppressed TEV uptake and disrupted TEV-induced formation of the pre-metastatic niche and melanoma lung metastases. These results suggest the importance of CH25H in defense against education of normal cells by TEV and argue for the use of reserpine in adjuvant melanoma therapy.

Viral dedication to vigorous destruction of interferon receptors

Interferons (IFNs) exhibit forceful inhibitory activities against numerous viruses by inducing synthesis of anti-viral proteins or promoting immune cell functions, which help eradicate the vicious microbes. Consequently, the degree to which viruses evade or counterattack IFN responses influences viral pathogenicity. Viruses have developed many strategies to interfere with the synthesis of IFNs or IFN receptor signaling pathway. Furthermore, multiple viruses decrease levels of IFN receptors via diverse tactics, which include decreasing type I IFN receptor mRNA expression, blocking post-translational modification of the receptor, and degrading IFN receptors. Recently, influenza virus was found to induce CK1α-induced phosphorylation and subsequent degradation of the receptor for type I and II IFNs. In this review, viral mechanisms that remove IFN receptors are summarized with an emphasis on the mechanisms for virus-induced degradation of IFN receptors.

Plasticity of Type I Interferon-Mediated Responses in Cancer Therapy: From Anti-tumor Immunity to Resistance

The efficacy of several therapeutic strategies against cancer, including cytotoxic drugs, radiotherapy, targeted immunotherapies and oncolytic viruses, depend on intact type I interferon (IFN) signaling for the promotion of both direct (tumor cell inhibition) and indirect (anti-tumor immune responses) effects. Malfunctions of this pathway in tumor cells or in immune cells may be responsible for the lack of response or resistance. Although type I IFN signaling is required to trigger anti-tumor immunity, emerging evidence indicates that chronic activation of type I IFN pathway may be involved in mediating resistance to different cancer treatments. The plastic and dynamic features of type I IFN responses should be carefully considered to fully exploit the therapeutic potential of strategies targeting IFN signaling. Here, we review available evidence supporting the involvement of type I IFN signaling in mediating resistance to various cancer therapies and highlight the most promising modalities that are being tested to overcome resistance.

Interferon regulatory factor 1 inactivation in human cancer

Interferon regulatory factors (IRFs) are a group of closely related proteins collectively referred to as the IRF family. Members of this family were originally recognized for their roles in inflammatory responses; however, recent research has suggested that they are also involved in tumor biology. This review focusses on current knowledge of the roles of IRF-1 and IRF-2 in human cancer, with particular attention paid to the impact of IRF-1 inactivation. The different mechanisms underlying IRF-1 inactivation and their implications for human cancers and the potential importance of IRF-1 in immunotherapy are also summarized.

Casein Kinase 1α Mediates the Degradation of Receptors for Type I and Type II Interferons Caused by Hemagglutinin of Influenza A Virus

Although influenza A virus (IAV) evades cellular defense systems to effectively propagate in the host, the viral immune-evasive mechanisms are incompletely understood. Our recent data showed that hemagglutinin (HA) of IAV induces degradation of type I IFN receptor 1 (IFNAR1). Here, we demonstrate that IAV HA induces degradation of type II IFN (IFN-γ) receptor 1 (IFNGR1), as well as IFNAR1, via casein kinase 1α (CK1α), resulting in the impairment of cellular responsiveness to both type I and II IFNs. IAV infection or transient HA expression induced degradation of both IFNGR1 and IFNAR1, whereas HA gene-deficient IAV failed to downregulate the receptors. IAV HA caused the phosphorylation and ubiquitination of IFNGR1, leading to the lysosome-dependent degradation of IFNGR1. Influenza viral HA strongly decreased cellular sensitivity to type II IFNs, as it suppressed the activation of STAT1 and the induction of IFN-γ-stimulated genes in response to exogenously supplied recombinant IFN-γ. Importantly, CK1α, but not p38 MAP kinase or protein kinase D2, was proven to be critical for HA-induced degradation of both IFNGR1 and IFNAR1. Pharmacologic inhibition of CK1α or small interfering RNA (siRNA)-based knockdown of CK1α repressed the degradation processes of both IFNGR1 and IFNAR1 triggered by IAV infection. Further, CK1α was shown to be pivotal for proficient replication of IAV. Collectively, the results suggest that IAV HA induces degradation of IFN receptors via CK1α, creating conditions favorable for viral propagation. Therefore, the study uncovers a new immune-evasive pathway of influenza virus.IMPORTANCE Influenza A virus (IAV) remains a grave threat to humans, causing seasonal and pandemic influenza. Upon infection, innate and adaptive immunity, such as the interferon (IFN) response, is induced to protect hosts against IAV infection. However, IAV seems to be equipped with tactics to evade the IFN-mediated antiviral responses, although the detailed mechanisms need to be elucidated. In the present study, we show that IAV HA induces the degradation of the type II IFN receptor IFNGR1 and thereby substantially attenuates cellular responses to IFN-γ. Of note, a cellular kinase, casein kinase 1α (CK1α), is crucial for IAV HA-induced degradation of both IFNGR1 and IFNAR1. Accordingly, CK1α is proven to positively regulate IAV propagation. Thus, this study unveils a novel strategy employed by IAV to evade IFN-mediated antiviral activities. These findings may provide new insights into the interplay between IAV and host immunity to impact influenza virus pathogenicity.

A PERK-miR-211 axis suppresses circadian regulators and protein synthesis to promote cancer cell survival

The unfolded protein response (UPR) is a stress-activated signalling pathway that regulates cell proliferation, metabolism and survival. The circadian clock coordinates metabolism and signal transduction with light/dark cycles. We explore how UPR signalling interfaces with the circadian clock. UPR activation induces a 10 h phase shift in circadian oscillations through induction of miR-211, a PERK-inducible microRNA that transiently suppresses both Bmal1 and Clock, core circadian regulators. Molecular investigation reveals that miR-211 directly regulates Bmal1 and Clock via distinct mechanisms. Suppression of Bmal1 and Clock has the anticipated impact on expression of select circadian genes, but we also find that repression of Bmal1 is essential for UPR-dependent inhibition of protein synthesis and cell adaptation to stresses that disrupt endoplasmic reticulum homeostasis. Our data demonstrate that c-Myc-dependent activation of the UPR inhibits Bmal1 in Burkitt's lymphoma, thereby suppressing both circadian oscillation and ongoing protein synthesis to facilitate tumour progression.

Rotavirus Degrades Multiple Interferon (IFN) Type Receptors To Inhibit IFN Signaling and Protects against Mortality from Endotoxin in Suckling Mice

STAT1 phosphorylation in response to exogenous interferon (IFN) administration can be inhibited by rotaviral replication both in vitro and in vivo In addition many rotavirus strains are resistant to the actions of different IFN types. The regulation by rotaviruses (RVs) of antiviral pathways mediated by multiple IFN types is not well understood. In this study, we find that during infection in vitro and in vivo, RVs significantly deplete IFN type I, II, and III receptors (IFNRs). Regulation of IFNRs occurred exclusively within RV-infected cells and could be abrogated by inhibiting the lysosomal-endosomal degradation pathway. In vitro, IFNR degradation was conserved across multiple RV strains that differ in their modes of regulating IFN induction. In suckling mice, exogenously administered type I, II, or III IFN induced phosphorylation of STAT1-Y701 within intestinal epithelial cells (IECs) of suckling mice. Murine EW strain RV infection transiently activated intestinal STAT1 at 1 day postinfection (dpi) but not subsequently at 2 to 3 dpi. In response to injection of purified IFN-α/β or -λ, IECs in EW-infected mice exhibited impaired STAT1-Y701 phosphorylation, correlating with depletion of different intestinal IFNRs and impaired IFN-mediated transcription. The ability of EW murine RV to inhibit multiple IFN types led us to test protection of suckling mice from endotoxin-mediated shock, an outcome that is dependent on the host IFN response. Compared to mortality in controls, mice infected with EW murine RV were substantially protected against mortality following parenteral endotoxin administration. These studies identify a novel mechanism of IFN subversion by RV and reveal an unexpected protective effect of RV infection on endotoxin-mediated shock in suckling mice.IMPORTANCE Antiviral functions of types I, II, and III IFNs are mediated by receptor-dependent activation of STAT1. Here, we find that RV degrades the types I, II, and III IFN receptors (IFNRs) in vitro In a suckling mouse model, RV effectively blocked STAT1 activation and transcription following injection of different purified IFNs. This correlated with significantly decreased protein expression of intestinal types I and II IFNRs. Recent studies demonstrate that in mice lipopolysaccharide (LPS)-induced lethality is prevented by genetic ablation of IFN signaling genes such as IFNAR1 and STAT1. When suckling mice were infected with RV, they were substantially protected from lethal exposure to endotoxin. These findings provide novel insights into the mechanisms underlying rotavirus regulation of different interferons and are likely to stimulate new research into both rotavirus pathogenesis and endotoxemia.

miR-93-5p/IFNAR1 axis promotes gastric cancer metastasis through activating the STAT3 signaling pathway

Aberrant expression of microRNAs (miRNAs) plays an important role in gastric cancer (GC) development. miR-93-5p has shown opposing functions in different types of cancers, but the exact expression pattern and molecular mechanism of miR-93-5p in GC development remain to be elucidated. Here, we reported that miR-93-5p expression was increased in GC tissues compared with the adjacent normal tissues and that its overexpression was correlated with distant metastasis and poor survival in GC patients. miR-93-5p knockdown inhibited the migration, invasion and proliferation of GC cells in vitro and in vivo, while its overexpression displayed an opposite result. Using an mRNA microarray, we found that miR-93-5p significantly downregulated IFNAR1 expression in GC cells, which was further identified as a direct target of miR-93-5p. IFNAR1 knockdown promoted GC cell migration and invasion, but its restoration could rescue GC cell migration and invasion induced by miR-93-5p overexpression. Moreover, miR-93-5p-IFNAR1 axis increased MMP9 expression via STAT3 pathway in GC cells. Taken together, we reveal that miR-93-5p overexpression is associated with the poor survival of GC patients and miR-93-5p-IFNAR1 axis promotes GC metastasis through activation of STAT3 pathway.

Downregulation of the IFNAR1 chain of type 1 interferon receptor contributes to the maintenance of the haematopoietic stem cells

Recent studies demonstrated that prolonged exposure of haematopoietic stem cells (HSCs) to type I interferons (IFN) stimulates HSCs entrance into cell cycle, continuous proliferation and eventual exhaustion, which could be prevented by ablation of the Ifnar1 chain of IFN receptor. Given that levels IFNAR1 expression can be robustly affected by IFN-independent ubiquitination and downregulation of IFNAR1 in response to activation of protein kinases such as protein kinase R-like endoplasmic reticulum kinase (PERK) and casein kinase 1α (CK1α), we aimed to determine the role of IFNAR1 downregulation in the maintenance of HSCs. Mice harboring the ubiquitination-deficient Ifnar1^S526A allele displayed greater levels of haematopoietic cell progenitors but reduced numbers of the long-term HSCs compared with wild type mice and animals lacking Ifnar1. Studies using competitive bone marrow repopulation assays showed that CK1α (but not PERK) is essential for the long-term HSCs function. Concurrent ablation of Ifnar1 led to a modest attenuation of the CK1α-null phenotype indicating that, although other CK1α targets are likely to be important, IFNAR1 downregulation can contribute to the maintenance of the HSCs function.

RIG-I Resists Hypoxia-Induced Immunosuppression and Dedifferentiation

A hypoxic tumor microenvironment is linked to poor prognosis. It promotes tumor cell dedifferentiation and metastasis and desensitizes tumor cells to type-I IFN, chemotherapy, and irradiation. The cytoplasmic immunoreceptor retinoic acid-inducible gene-I (RIG-I) is ubiquitously expressed in tumor cells and upon activation by 5'-triphosphate RNA (3pRNA) drives the induction of type I IFN and immunogenic cell death. Here, we analyzed the impact of hypoxia on the expression of RIG-I in various human and murine tumor and nonmalignant cell types and further investigated its function in hypoxic murine melanoma. 3pRNA-inducible RIG-I-expression was reduced in hypoxic melanoma cells compared with normoxic controls, a phenomenon that depended on the hypoxia-associated transcription factor HIF1α. Still, RIG-I functionality was conserved in hypoxic melanoma cells, whereas responsiveness to recombinant type-I IFN was abolished, due to hypoxia-induced loss of type I IFN receptor expression. Likewise, RIG-I activation in hypoxic melanoma cells, but not exposure to recombinant IFNα, provoked melanocyte antigen-specific CD8⁺ T-cell and NK-cell attack. Scavenging of hypoxia-induced reactive oxygen species by vitamin C restored the inducible expression of RIG-I under hypoxia in vitro, boosted in vitro anti-melanoma NK- and CD8⁺ T-cell attack, and augmented 3pRNA antitumor efficacy in vivo These results demonstrate that RIG-I remains operational under hypoxia and that RIG-I function is largely insensitive to lower cell surface expression of the IFNα receptor. RIG-I function could be fortified under hypoxia by the combined use of 3pRNA with antioxidants. Cancer Immunol Res; 5(6); 455-67. ©2017 AACR.

Expression of the IFNAR1 chain of type 1 interferon receptor in benign cells protects against progression of acute leukemia

Type I interferons (IFN) were widely used for leukemia treatment. These cytokines act on cell surface receptor consisting of the IFNAR1/2 chains to induce anti-tumorigenic effects. Given that levels of IFNAR1 can be regulated by phosphorylation-driven ubiquitination and degradation that undermines IFN signaling and anti-tumorigenic effects, we sought to determine the importance of IFNAR1 downregulation in progression of acute leukemia. Using knock-in mice deficient in downregulation of IFNAR1, we uncovered that IFNAR1 expression in stromal benign cells functions to protect against progression of leukemia. We discuss putative mechanisms of this regulation and potential of therapeutic targeting of IFNAR1 downregulation to treat leukemia.

The molecular basis for differential type I interferon signaling

Type I interferons (IFN-1) are cytokines that affect the expression of thousands of genes, resulting in profound cellular changes. IFN-1 activates the cell by dimerizing its two-receptor chains, IFNAR1 and IFNAR2, which are expressed on all nucleated cells. Despite a similar mode of binding, the different IFN-1s activate a spectrum of activities. The causes for differential activation may stem from differences in IFN-1-binding affinity, duration of binding, number of surface receptors, induction of feedbacks, and cell type-specific variations. All together these will alter the signal that is transmitted from the extracellular domain inward. The intracellular domain binds, directly or indirectly, different effector proteins that transmit signals. The composition of effector molecules deviates between different cell types and tissues, inserting an additional level of complexity to the system. Moreover, IFN-1s do not act on their own, and clearly there is much cross-talk between the activated effector molecules by IFN-1 and other cytokines. The outcome generated by all of these factors (processing step) is an observed phenotype, which can be the transformation of the cell to an antiviral state, differentiation of the cell to a specific immune cell, senescence, apoptosis, and many more. IFN-1 activities can be divided into robust and tunable. Antiviral activity, which is stimulated by minute amounts of IFN-1 and is common to all cells, is termed robust. The other activities, which we term tunable, are cell type-specific and often require more stringent modes of activation. In this review, I summarize the current knowledge on the mode of activation and processing that is initiated by IFN-1, in perspective of the resulting phenotypes.

A Potent In Vivo Antitumor Efficacy of Novel Recombinant Type I Interferon

Purpose: Antiproliferative, antiviral, and immunomodulatory activities of endogenous type I IFNs (IFN1) prompt the design of recombinant IFN1 for therapeutic purposes. However, most of the designed IFNs exhibited suboptimal therapeutic efficacies against solid tumors. Here, we report evaluation of the in vitro and in vivo antitumorigenic activities of a novel recombinant IFN termed sIFN-I.Experimental Design: We compared primary and tertiary structures of sIFN-I with its parental human IFNα-2b, as well as affinities of these ligands for IFN1 receptor chains and pharmacokinetics. These IFN1 species were also compared for their ability to induce JAK-STAT signaling and expression of the IFN1-stimulated genes and to elicit antitumorigenic effects. Effects of sIFN-I on tumor angiogenesis and immune infiltration were also tested in transplanted and genetically engineered immunocompetent mouse models.Results: sIFN-I displayed greater affinity for IFNAR1 (over IFNAR2) chain of the IFN1 receptor and elicited a greater extent of IFN1 signaling and expression of IFN-inducible genes in human cells. Unlike IFNα-2b, sIFN-I induced JAK-STAT signaling in mouse cells and exhibited an extended half-life in mice. Treatment with sIFN-I inhibited intratumoral angiogenesis, increased CD8+ T-cell infiltration, and robustly suppressed growth of transplantable and genetically engineered tumors in immunodeficient and immunocompetent mice.Conclusions: These findings define sIFN-I as a novel recombinant IFN1 with potent preclinical antitumorigenic effects against solid tumor, thereby prompting the assessment of sIFN-I clinical efficacy in humans. Clin Cancer Res; 23(8); 2038-49. ©2016 AACR.

Role of interferon in melanoma: old hopes and new perspectives

INTRODUCTION

Interferons (IFNs) play a key role in modulating anti-microbial and antitumor immune responses. In oncology, past attempts to exploit IFNs therapeutically did not fulfill expectations, and had only modest clinical results, mostly limited to adjuvant melanoma treatment. The recent successes of immunotherapy in oncology have brought new attention to the potential of immune-modulatory agents like the IFNs. Areas covered: The authors review the biological effects of IFN on melanoma and immune cells. Then, the authors summarize the clinical results of adjuvant and therapeutic IFN in melanoma, giving focus to possible prognostic factors and new on-going clinical trials. Expert opinion: IFNs offer intriguing opportunities for synergism between conventional treatments and recently introduced molecular-targeted and immunotherapy approaches. However, the full comprehension of all IFN effects and their multiple biologic links is challenging. A strong commitment toward parallel translational research is needed to facilitate the interpretation of IFN's expected and unexpected effects, guiding the rational design of informative clinical studies.

Inactivation of Interferon Receptor Promotes the Establishment of Immune Privileged Tumor Microenvironment

Refractoriness of solid tumors, including colorectal cancers (CRCs), to immunotherapies is attributed to the immunosuppressive tumor microenvironment that protects malignant cells from cytotoxic T lymphocytes (CTLs). We found that downregulation of the type I interferon receptor chain IFNAR1 occurs in human CRC and mouse models of CRC. Downregulation of IFNAR1 in tumor stroma stimulated CRC development and growth, played a key role in formation of the immune-privileged niche, and predicted poor prognosis in human CRC patients. Genetic stabilization of IFNAR1 improved CTL survival and increased the efficacy of the chimeric antigen receptor T cell transfer and PD-1 inhibition. Likewise, pharmacologic stabilization of IFNAR1 suppressed tumor growth providing the rationale for upregulating IFNAR1 to improve anti-cancer therapies.

Therapeutic Elimination of the Type 1 Interferon Receptor for Treating Psoriatic Skin Inflammation

Phototherapy with UV light is a standard treatment for psoriasis, yet the mechanisms underlying the therapeutic effects are not well understood. Studies in human and mouse keratinocytes and in the skin tissues from human patients and mice showed that UV treatment triggers ubiquitination and downregulation of the type I IFN receptor chain IFNAR1, leading to suppression of IFN signaling and an ensuing decrease in the expression of inflammatory cytokines and chemokines. The severity of imiquimod-induced psoriasiform inflammation was greatly exacerbated in skin of mice deficient in IFNAR1 ubiquitination (Ifnar1(SA)). Furthermore, these mice did not benefit from UV phototherapy. Pharmacologic induction of IFNAR1 ubiquitination and degradation by an antiprotozoal agent halofuginone also relieved psoriasiform inflammation in wild-type but not in Ifnar1(SA) mice. These data identify downregulation of IFNAR1 by UV as a major mechanism of the UV therapeutic effects against the psoriatic inflammation and provide a proof of principle for future development of agents capable of inducing IFNAR1 ubiquitination and downregulation for the treatment of psoriasis.

Suppression of Type I Interferon Signaling Overcomes Oncogene-Induced Senescence and Mediates Melanoma Development and Progression

Oncogene activation induces DNA damage responses and cell senescence. We report a key role of type I interferons (IFNs) in oncogene-induced senescence. IFN signaling-deficient melanocytes expressing activated Braf do not exhibit senescence and develop aggressive melanomas. Restoration of IFN signaling in IFN-deficient melanoma cells induces senescence and suppresses melanoma progression. Additional data from human melanoma patients and mouse transplanted tumor models suggest the importance of non-cell-autonomous IFN signaling. Inactivation of the IFN pathway is mediated by the IFN receptor IFNAR1 downregulation that invariably occurs during melanoma development. Mice harboring an IFNAR1 mutant, which is partially resistant to downregulation, delay melanoma development, suppress metastatic disease, and better respond to BRAF or PD-1 inhibitors. These results suggest that IFN signaling is an important tumor-suppressive pathway that inhibits melanoma development and progression and argue for targeting IFNAR1 downregulation to prevent metastatic disease and improve the efficacy of molecularly target and immune-targeted melanoma therapies.

Antitumour actions of interferons: implications for cancer therapy

The interferons (IFNs) are a family of cytokines that protect against disease by direct effects on target cells and by activating immune responses. The production and actions of IFNs are finely tuned to achieve maximal protection and avoid the potential toxicity associated with excessive responses. IFNs are back in the spotlight owing to mounting evidence that is reshaping how we can exploit this pathway therapeutically. As IFNs can be produced by, and act on, both tumour cells and immune cells, understanding this reciprocal interaction will enable the development of improved single-agent or combination therapies that exploit IFN pathways and new 'omics'-based biomarkers to indicate responsive patients.

Anti-metastatic functions of type 1 interferons: Foundation for the adjuvant therapy of cancer

The anti-tumorigenic effects that type 1 interferons (IFN1) elicited in the in vitro studies prompted consideration of IFN1 as a potent candidate for clinical treatment. Though not all patients responded to IFN1, clinical trials have shown that patients with high risk melanoma, a highly refractory solid malignancy, benefit greatly from intermediate IFN1 treatment in regards to relapse-free and distant-metastasis-free survival. The mechanisms by which IFN1 treatment at early stages of disease suppress tumor recurrence or metastatic incidence are not fully understood. Intracellular IFN1 signaling is known to affect cell differentiation, proliferation, and apoptosis. Moreover, recent studies have revealed specific IFN1-regulated genes that may contribute to IFN1-mediated suppression of cancer progression and metastasis. In concert, expression of these different IFN1 stimulated genes may impede numerous mechanisms that mediate metastatic process. Though, IFN1 treatment is still utilized as part of standard care for metastatic melanoma (alone or in combination with other therapies), cancers find the ways to develop insensitivity to IFN1 treatment allowing for unconstrained disease progression. To determine how and when IFN1 treatment would be most efficacious during disease progression, we must understand how IFN1 signaling affects different metastasis steps. Here, we specifically focus on the anti-metastatic role of endogenous IFN1 and parameters that may help to use pharmaceutical IFN1 in the adjuvant treatment to prevent cancer recurrence and metastatic disease.

Hemagglutinin of Influenza A Virus Antagonizes Type I Interferon (IFN) Responses by Inducing Degradation of Type I IFN Receptor 1

Influenza A virus (IAV) employs diverse strategies to circumvent type I interferon (IFN) responses, particularly by inhibiting the synthesis of type I IFNs. However, it is poorly understood if and how IAV regulates the type I IFN receptor (IFNAR)-mediated signaling mode. In this study, we demonstrate that IAV induces the degradation of IFNAR subunit 1 (IFNAR1) to attenuate the type I IFN-induced antiviral signaling pathway. Following infection, the level of IFNAR1 protein, but not mRNA, decreased. Indeed, IFNAR1 was phosphorylated and ubiquitinated by IAV infection, which resulted in IFNAR1 elimination. The transiently overexpressed IFNAR1 displayed antiviral activity by inhibiting virus replication. Importantly, the hemagglutinin (HA) protein of IAV was proved to trigger the ubiquitination of IFNAR1, diminishing the levels of IFNAR1. Further, influenza A viral HA1 subunit, but not HA2 subunit, downregulated IFNAR1. However, viral HA-mediated degradation of IFNAR1 was not caused by the endoplasmic reticulum (ER) stress response. IAV HA robustly reduced cellular sensitivity to type I IFNs, suppressing the activation of STAT1/STAT2 and induction of IFN-stimulated antiviral proteins. Taken together, our findings suggest that IAV HA causes IFNAR1 degradation, which in turn helps the virus escape the powerful innate immune system. Thus, the research elucidated an influenza viral mechanism for eluding the IFNAR signaling pathway, which could provide new insights into the interplay between influenza virus and host innate immunity.

IMPORTANCE

Influenza A virus (IAV) infection causes significant morbidity and mortality worldwide and remains a major health concern. When triggered by influenza viral infection, host cells produce type I interferon (IFN) to block viral replication. Although IAV was shown to have diverse strategies to evade this powerful, IFN-mediated antiviral response, it is not well-defined if IAV manipulates the IFN receptor-mediated signaling pathway. Here, we uncovered that influenza viral hemagglutinin (HA) protein causes the degradation of type I IFN receptor subunit 1 (IFNAR1). HA promoted phosphorylation and polyubiquitination of IFNAR1, which facilitated the degradation of this receptor. The HA-mediated elimination of IFNAR1 notably decreased the cells' sensitivities to type I IFNs, as demonstrated by the diminished expression of IFN-induced antiviral genes. This discovery could help us understand how IAV regulates the host innate immune response to create an environment optimized for viral survival in host cells.

Type I interferons mediate pancreatic toxicities of PERK inhibition

The great preclinical promise of the pancreatic endoplasmic reticulum kinase (PERK) inhibitors in neurodegenerative disorders and cancers is marred by pancreatic injury and diabetic syndrome observed in PERK knockout mice and humans lacking PERK function and suffering from Wolcott-Rallison syndrome. PERK mediates many of the unfolded protein response (UPR)-induced events, including degradation of the type 1 interferon (IFN) receptor IFNAR1 in vitro. Here we report that whole-body or pancreas-specific Perk ablation in mice leads to an increase in IFNAR1 protein levels and signaling in pancreatic tissues. Concurrent IFNAR1 deletion attenuated the loss of PERK-deficient exocrine and endocrine pancreatic tissues and prevented the development of diabetes. Experiments using pancreas-specific Perk knockouts, bone marrow transplantation, and cultured pancreatic islets demonstrated that stabilization of IFNAR1 and the ensuing increased IFN signaling in pancreatic tissues represents a major driver of injury triggered by Perk loss. Neutralization of IFNAR1 prevented pancreatic toxicity of PERK inhibitor, indicating that blocking the IFN pathway can mitigate human genetic disorders associated with PERK deficiency and help the clinical use of PERK inhibitors.