Interferons: therapy for cancer

An important component of the innate immune response of the host in viral infection is the production of type I interferons. Efforts to understand the molecular mechanisms by which animal viruses and also double-stranded RNA trigger the induction of interferon (IFN) 2The abbreviations used are: IFN, interferon; dsRNA, double-stranded RNA; IRF, interferon regulatory factor; IPS-1, interferon promoter stimulator 1; MyD88, myeloid differentiation primary response protein 88; NF-κB, nuclear factor-κB; RIG-I, retinoic acid inducible gene I; RLR, RIG-I-like receptor; ssRNA, single-stranded RNA; TLR, Toll-like receptor; TRIF, Toll/interleukin 1 receptor domain-containing adaptor protein inducing interferon.2The abbreviations used are: IFN, interferon; dsRNA, double-stranded RNA; IRF, interferon regulatory factor; IPS-1, interferon promoter stimulator 1; MyD88, myeloid differentiation primary response protein 88; NF-κB, nuclear factor-κB; RIG-I, retinoic acid inducible gene I; RLR, RIG-I-like receptor; ssRNA, single-stranded RNA; TLR, Toll-like receptor; TRIF, Toll/interleukin 1 receptor domain-containing adaptor protein inducing interferon. have led to the identification of cellular sensors of viral infection. The first two minireviews in this issue provide updates on two kinds of nucleic acid sensors and the biochemical pathways by which they signal the production of interferon. One type of sensor is the family of cytosolic receptor proteins (RIG-I, MDA5, LGP2) known as the retinoic acid-inducible gene I (RIG-I)-like receptors (RLR). The other type of sensor includes members of the Toll-like receptor (TLR) family of cell surface and endosomal membrane protein receptors (TLR3, -7, -8, and -9). These minireviews focus on the biochemical and cellular aspects of the signaling pathways activated by RNA, both single-stranded (ss) RNA and double-stranded (ds) RNA, including the nature of the RLR and TLR sensor proteins and the adaptors through which they signal the production of IFN in virus-infected cells. The third minireview focuses on the structure and function of interferon regulatory factor (IRF) 3 and, to an extent, IRF-7, which are activated by the RLR and TLR signaling pathways. These IRFs, together with the nuclear factor-κB (NF-κB) and activator protein 1 factors lead to the transcriptional activation of the type I interferon β (IFN-β) gene.Interferon was discovered as an antiviral cytokine 50 years ago during seminal studies on virus interference (1Isaacs A. Lindenmann J. Proc. R. Soc. Lond. Ser. B Biol. Sci. 1957; 147: 258-267Crossref PubMed Google Scholar). We now have considerable knowledge about the biology and biochemistry of the IFN system and the critically important role that IFN plays in the innate immune response (2Samuel C.E. Clin. Microbiol. Rev. 2001; 14: 778-809Crossref PubMed Scopus (2115) Google Scholar). Most recently, exciting progress has been made toward elucidating the biochemical pathways by which the host recognizes invading viral pathogens and triggers the production of the type I IFNs, principally IFN-β. Aspects of the RLR and TLR signaling pathways leading to the induction of type I IFN expression in response to viral nucleic acids are summarized in Fig. 1. The RIG-I-like receptors signal via the mitochondrial membrane-associated interferon promoter stimulator 1 (IPS-1) adaptor protein. The Toll-like receptors signal via either the TRIF (Toll/interleukin 1 receptor domain-containing adaptor protein inducing IFN-β) adaptor protein in the case of TLR3 or the MyD88 (myeloid differentiation primary response protein 88) adaptor protein in the case of TLR7, -8, and -9. These signaling pathways lead to the activation of IRF and NF-κB factors that play a key role in the induction of type I IFN expression.In the first minireview, Mitsutoshi Yoneyama and Takashi Fujita at Kyoto University in their article entitled "Function of RIG-I-like Receptors in Antiviral Innate Immunity" consider new developments in both the biochemistry and biology of the cellular RIG-I helicase family of RNA sensors (3Yoneyama M. Fujita T. J. Biol. Chem. 2007; 282: 15315-15318Abstract Full Text Full Text PDF PubMed Scopus (247) Google Scholar). The functional domains and activities of the RLRs, the nature of the viral RNAs that trigger IFN production in an RLR-dependent manner, the proteins that constitute the RLR signaling pathway, and the antagonism of RLR signaling by viral gene products are discussed.The second minireview of the series by Satoshi Uematsu and Shizuo Akira at Osaka University entitled "Toll-like Receptor and Type I Interferons" focuses on recent developments in understanding the TLR receptors that recognize viral nucleic acids including TLR3, which recognizes dsRNA; TLR7 and TLR8, which recognize G- and U-rich ssRNAs; and TLR9, which recognizes CpG-containing DNA (4Uematsu S. Akira S. J. Biol. Chem. 2007; 282: 15319-15324Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar). In addition, progress in understanding the cell surface recognition of viral envelope components by TLR4 leading to IFN induction is discussed. The roles of the RLRs and individual TLRs are considered in the production of IFN-β and IFN-α in different types of cells, including fibroblasts, conventional dendritic cells (cDCs), and plasmacytoid dendritic cells (pDCs).The final minireview of this thematic series on triggers of antiviral innate immunity focuses on the centrally important IRFs involved in transcriptional activation of the type I interferon gene promoters. John Hiscott at McGill University in his minireview entitled "Triggering the Innate Antiviral Response through IRF-3 Activation" describes the role that the transcription factor IRF-3, as well as the closely related factor IRF-7, play in the RLR-dependent and TLR-dependent signaling pathways (5Hiscott J. J. Biol. Chem. 2007; 282: 15325-15329Abstract Full Text Full Text PDF PubMed Scopus (363) Google Scholar).Much progress has been made in elucidating the biochemical mechanisms by which viral infection causes the transcriptional activation of type I interferon production through the RIG-I-like receptor and Toll-like receptor signaling pathways. The authors and editors hope that this minireview series on antiviral innate immunity will enable researchers in the basic and clinical sciences to better appreciate the signaling pathways and the mechanistic insights gained in the area of viral recognition by RLRs and TLRs leading to the expression of type I interferon genes. An important component of the innate immune response of the host in viral infection is the production of type I interferons. Efforts to understand the molecular mechanisms by which animal viruses and also double-stranded RNA trigger the induction of interferon (IFN) 2The abbreviations used are: IFN, interferon; dsRNA, double-stranded RNA; IRF, interferon regulatory factor; IPS-1, interferon promoter stimulator 1; MyD88, myeloid differentiation primary response protein 88; NF-κB, nuclear factor-κB; RIG-I, retinoic acid inducible gene I; RLR, RIG-I-like receptor; ssRNA, single-stranded RNA; TLR, Toll-like receptor; TRIF, Toll/interleukin 1 receptor domain-containing adaptor protein inducing interferon.2The abbreviations used are: IFN, interferon; dsRNA, double-stranded RNA; IRF, interferon regulatory factor; IPS-1, interferon promoter stimulator 1; MyD88, myeloid differentiation primary response protein 88; NF-κB, nuclear factor-κB; RIG-I, retinoic acid inducible gene I; RLR, RIG-I-like receptor; ssRNA, single-stranded RNA; TLR, Toll-like receptor; TRIF, Toll/interleukin 1 receptor domain-containing adaptor protein inducing interferon. have led to the identification of cellular sensors of viral infection. The first two minireviews in this issue provide updates on two kinds of nucleic acid sensors and the biochemical pathways by which they signal the production of interferon. One type of sensor is the family of cytosolic receptor proteins (RIG-I, MDA5, LGP2) known as the retinoic acid-inducible gene I (RIG-I)-like receptors (RLR). The other type of sensor includes members of the Toll-like receptor (TLR) family of cell surface and endosomal membrane protein receptors (TLR3, -7, -8, and -9). These minireviews focus on the biochemical and cellular aspects of the signaling pathways activated by RNA, both single-stranded (ss) RNA and double-stranded (ds) RNA, including the nature of the RLR and TLR sensor proteins and the adaptors through which they signal the production of IFN in virus-infected cells. The third minireview focuses on the structure and function of interferon regulatory factor (IRF) 3 and, to an extent, IRF-7, which are activated by the RLR and TLR signaling pathways. These IRFs, together with the nuclear factor-κB (NF-κB) and activator protein 1 factors lead to the transcriptional activation of the type I interferon β (IFN-β) gene. Interferon was discovered as an antiviral cytokine 50 years ago during seminal studies on virus interference (1Isaacs A. Lindenmann J. Proc. R. Soc. Lond. Ser. B Biol. Sci. 1957; 147: 258-267Crossref PubMed Google Scholar). We now have considerable knowledge about the biology and biochemistry of the IFN system and the critically important role that IFN plays in the innate immune response (2Samuel C.E. Clin. Microbiol. Rev. 2001; 14: 778-809Crossref PubMed Scopus (2115) Google Scholar). Most recently, exciting progress has been made toward elucidating the biochemical pathways by which the host recognizes invading viral pathogens and triggers the production of the type I IFNs, principally IFN-β. Aspects of the RLR and TLR signaling pathways leading to the induction of type I IFN expression in response to viral nucleic acids are summarized in Fig. 1. The RIG-I-like receptors signal via the mitochondrial membrane-associated interferon promoter stimulator 1 (IPS-1) adaptor protein. The Toll-like receptors signal via either the TRIF (Toll/interleukin 1 receptor domain-containing adaptor protein inducing IFN-β) adaptor protein in the case of TLR3 or the MyD88 (myeloid differentiation primary response protein 88) adaptor protein in the case of TLR7, -8, and -9. These signaling pathways lead to the activation of IRF and NF-κB factors that play a key role in the induction of type I IFN expression. In the first minireview, Mitsutoshi Yoneyama and Takashi Fujita at Kyoto University in their article entitled "Function of RIG-I-like Receptors in Antiviral Innate Immunity" consider new developments in both the biochemistry and biology of the cellular RIG-I helicase family of RNA sensors (3Yoneyama M. Fujita T. J. Biol. Chem. 2007; 282: 15315-15318Abstract Full Text Full Text PDF PubMed Scopus (247) Google Scholar). The functional domains and activities of the RLRs, the nature of the viral RNAs that trigger IFN production in an RLR-dependent manner, the proteins that constitute the RLR signaling pathway, and the antagonism of RLR signaling by viral gene products are discussed. The second minireview of the series by Satoshi Uematsu and Shizuo Akira at Osaka University entitled "Toll-like Receptor and Type I Interferons" focuses on recent developments in understanding the TLR receptors that recognize viral nucleic acids including TLR3, which recognizes dsRNA; TLR7 and TLR8, which recognize G- and U-rich ssRNAs; and TLR9, which recognizes CpG-containing DNA (4Uematsu S. Akira S. J. Biol. Chem. 2007; 282: 15319-15324Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar). In addition, progress in understanding the cell surface recognition of viral envelope components by TLR4 leading to IFN induction is discussed. The roles of the RLRs and individual TLRs are considered in the production of IFN-β and IFN-α in different types of cells, including fibroblasts, conventional dendritic cells (cDCs), and plasmacytoid dendritic cells (pDCs). The final minireview of this thematic series on triggers of antiviral innate immunity focuses on the centrally important IRFs involved in transcriptional activation of the type I interferon gene promoters. John Hiscott at McGill University in his minireview entitled "Triggering the Innate Antiviral Response through IRF-3 Activation" describes the role that the transcription factor IRF-3, as well as the closely related factor IRF-7, play in the RLR-dependent and TLR-dependent signaling pathways (5Hiscott J. J. Biol. Chem. 2007; 282: 15325-15329Abstract Full Text Full Text PDF PubMed Scopus (363) Google Scholar). Much progress has been made in elucidating the biochemical mechanisms by which viral infection causes the transcriptional activation of type I interferon production through the RIG-I-like receptor and Toll-like receptor signaling pathways. The authors and editors hope that this minireview series on antiviral innate immunity will enable researchers in the basic and clinical sciences to better appreciate the signaling pathways and the mechanistic insights gained in the area of viral recognition by RLRs and TLRs leading to the expression of type I interferon genes.

Since the interferon (IFN) system involves both IFN producing and IFN responding cells, it is possible to study separately these phenomena, relating them to disease entities as well as to response to therapy. Numerous studies in animals and man suggest effectiveness of IFN and IFN inducer therapy in cancer. However, the competency of the various components of the endogenous IFN system in malignancy has received little attention. These studies show that in malignancy there may be (1) a high incidence of elevated blood levels of IFN; (2) a deficient response of peripheral blood mononuclear cells to endogenous and exogenous IFN; and (3) increased uninduced in vitro IFN production by these cells. These findings indicate that cancer patients are equipped with the ability to produce IFN and suggest that it may be the deficient response of their cells to IFN that plays a role in the development and progression of the disease. Furthermore, the finding of increased spontaneous "uninduced" production of IFN by cells from cancer patients suggests the possibility of an intracellular inducer such as found in persistently virus-infected cells.

Natural killer (NK) cells are innate immune cells with the inherent ability to directly kill tumor and virus infected cells. Due to their ability to kill cancer cells without any prior priming, and their role in preventing metastasis NK cells have since long been the choice for autologous adoptive cell transfer therapy in cancer. However, poor expansion potential of PBMC derived NK cells in vitro is a major roadblock preventing the widespread use of NK cells in immunotherapy. We found that human NK cells isolated from lymph nodes (LNs) express higher levels of genes encoding for stem-like transcription factors (TCF7, LEF1, MYC) compared to NK cells from blood, spleen, bone marrow (BM) and lung. Therefore, we hypothesized that NK cells isolated from LNs will show superior expansion potential in vitro. Flow cytometric analysis shows that LN derived NK cells express high levels of TCF1 protein ex vivo, and show greater proliferation compared to NK cells isolated from blood, spleen and BM following stimulation with IL-2 and IL-15 in vitro. We also observed that a significant frequency of LN NK cells expressed TCF1 even after expansion, suggesting preserved proliferation potential of these cells. Additionally, the expanded NK cells from LN acquired properties of mature, highly functional NK cells such as increased expression of CD16, CD57 and higher Granzyme B expression. Lastly, LN derived NK cells also demonstrate enhanced cytolytic activity in vitro after expansion. Taken together our results suggest that in vitro expanded NK cells from LNs are potentially efficacious anti-tumor agents and could be leveraged for the development of future generation of NK cell directed immunotherapies.

The interferon (IFN) family of cytokines participates in the development of innate and acquired immune defenses against various pathogens and pathogenic stimuli. Discovered originally as a proteinaceous substance secreted from virus-infected cells that afforded immunity to neighboring cells from virus infection, these cytokines are now implicated in various human pathologies, including control of tumor development, cell differentiation, and autoimmunity. It is now believed that the IFN system (IFN genes and the genes induced by them, and the factors that regulate these processes) is a generalized alarm of cellular stress, including DNA damage. IFNs exert both beneficial and deleterious effects on the central nervous system (CNS). Our knowledge of the IFN-regulated processes in the CNS is far from being clear. In this article, we reviewed the current understanding of IFN signal transduction pathways and gene products that might have potential relevance to diseases of the CNS.

616. Enhancement of Antitumor Activity of Interferons by RNAi-Mediated Silencing of SOCS Genes in Tumor Cells

When I first read the manuscript that accompanies this editorial, upon its online publication on February 19th 2020(1), COVID-19 had already killed 2118 people in China, but only one person in Europe - an 80-year-old tourist from China, who died in France on the 15th February. I read the manuscript with grim fascination, as it was clear that SARS-CoV-2 had spread very rapidly in China which already had 74,576 cases and in South Korea which already had 58 cases, and that it was then invading Europe also, as France already had 12 cases, Germany 16, the UK 9, Italy 3, Spain 2 and other countries too.

Interferons (IFN) have been referred to as the prototypic biological response modifiers (BRM). Similarly to corticosteroids they induce a diversity of physiologic changes (1). It is conceivable then that IFNs work by different mechanisms than conventional cytotoxic agents and that their therapeutic optimal dose in cancer therapy not necessarily is equivalent to the maximum tolerated dose. The optimal treatment of cancer in addition involves combined use of various treatment modalities or various drugs. Experimental studies indicate that IFNs can be effectively combined with radiation and chemotherapy (2,3). In addition, IFNs augment the effects of each other and also other biologicals. Such new combined approaches provide possibilities for overcoming resistance of malignant cells. Preliminary evidence from phase I and II trials indicates that qualitatively similar clinical toxicities occur with IFNα, IFNβ and IFNγ (4). In an attempt further to define the clinical spectrum of side effects associated with various types, doses and schedules of IFNs alone and in combined regimens and to select a routine test battery for the monitoring of IFN toxicity we performed systematic large scale tests during four phase II studies in 43 patients with previously untreated lung cancer.

Viruses remodel metabolic processes and utilize host lipids for different stages of their life cycle. Our earlier studies have shown that the flavivirus Japanese encephalitis virus (JEV) downmodulates several key proteins involved in sterol and lipid biosynthesis. Through a lipidome analysis, we report that virus infection dysregulates nearly 41% of the cellular lipids in mouse embryonic fibroblasts (MEFs). This manifests as down-modulation of cholesterol, cholesterol esters, and glycerolipids and upregulation of ceramides and several phospholipids. Significant transcriptional downregulation of cholesterol biosynthetic pathway genes was observed in JEV-infected MEFs and mouse bone marrow-derived macrophages (BMDMs). This effect was dependent upon an active interferon (IFN) signaling node. Both knockdown and pharmacological inhibition of 7-dehydrocholesterol reductase (Dhcr7), a key regulator of the cholesterol biosynthesis pathway, exerted potent antiviral effects by blocking viral replication and enhancing IFN signaling. Direct supplementation with the Dhcr7 substrate, 7-dehydrocholesterol (7DHC), showed similar antiviral effects. A partial inhibition of virus replication was also observed in cells deficient for IFN signaling, highlighting an IFN-independent antiviral role of Dhcr7 inhibition. Overall, these findings underscore the potential of cholesterol biosynthetic pathway inhibition as an antiviral strategy for JEV.IMPORTANCEJEV, a mosquito-borne virus, is a leading global cause of virus-induced encephalitis with a significant disease burden in Southeast Asia. In this study, we observe that the cellular lipid composition changes in virus-infected cells, with lower levels of cholesterol and cholesterol esters. We also observe that specific genes of the cholesterol biosynthesis pathway are decreased, and this depends on the activation of the antiviral interferon (IFN) response. We have characterized one specific downregulated gene Dhcr7, which catalyzes the conversion of 7-dehydrocholesterol (7DHC) to cholesterol. Depletion of the Dhcr7-specific mRNA, inhibition through drugs, or adding the substrate 7DHC further enhanced the IFN response and blocked virus replication. Our study highlights that downregulation of the cholesterol biosynthetic pathway has the potential to be developed into an antiviral strategy. .

The sensitivity of a Us3-deletion mutant virus of herpes simplex virus type 1 (HSV-1) to consensus interferon (IFN) was compared with that of parental wild-type (wt) and the repaired viruses. Although one-step growth of the Us3-deficient virus in the IFN-treated HEp-2 cells was not markedly affected at a high multiplicity of infection (MOI), both the progeny virus yield and cytopathic effect were suppressed in a significantly higher degree in the mutant virus-infected cells than those in wt or the repaired virus-infected cells. This enhanced IFN-sensitivity of the mutant virus was more clearly demonstrated by the infection at a low MOI. In addition, both the size and number of plaques of the Us3-deficient virus in Vero cells were remarkably reduced with increasing concentrations of IFN, compared to those of wt or the repaired virus. These results indicate that the deletion of Us3 gene makes HSV-1 more sensitive to IFN.

85] Animal models for investigating antitumor effects of interferon

Despite the efficacy of hematopoietic stem cell transplantation (HSCT) as a cancer therapy, cancer relapse remains a significant complication. Natural killer (NK) cells are the first lymphoid population to recover after HSCT and can kill transformed or virally-infected cells without prior sensitization. Therefore, accelerating NK cell reconstitution may improve HSCT therapy. We utilized the combination of administering the stimulatory cytokine, IL-2 concurrently with the blockade of the immunosuppressive cytokine, transforming growth factor-beta (TGF-β) as a possible therapy to accelerate NK cell reconstitution after syngeneic HSCT. Resting C57BL/6 mice were treated with daily doses of IL-2 (2x105 IU) and anti-TGF-β (120ug, clone 1D11) every other day for one week. Although combinatorial therapy did not significantly expand NK cell numbers in comparison with IL-2 monotherapy, NK cytotoxicity, as measured by the ability to lyse Yac-1 tumor cells, was significantly greater. However in a HSCT model, combinatorial therapy administered in C57BL/6 mice starting at day 11 post-HSCT did significantly increase both the percentage of activated NK cells and NK tumor lytic ability compared with IL-2 alone. Additionally, mice showed no outward evidence of toxicity during administration of therapy. Together, these results suggest that this combination regimen improves reconstitution of NK cells after HSCT which may lead to better anti-viral and anti-tumor responses.

Natural killer (NK) cells are innate lymphocytes that participate in immune responses against virus-infected cells and tumors. As a countermeasure, viruses and tumors employ strategies to evade from NK cell-mediated immunosurveillance. In this review, we examine immune evasion strategies employed by viruses, focusing on examples from human cytomegalovirus (HCMV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We explore selected viral evasion mechanisms categorized into three classes: (1) providing ligands for the inhibitory receptor NKG2A, (2) down-regulating ligands for the activating receptor NKG2D, and (3) inducing the immunosuppressive cytokine transforming growth factor (TGF)-β. For each class, we draw parallels between immune evasion by viruses and tumors, reviewing potential opportunities for overcoming evasion in cancer therapy. We suggest that in-depth investigations of host-pathogen interactions between viruses and NK cells will not only deepen our understanding of viral immune evasion but also shed light on how NK cells counter such evasion attempts. Thus, due to the parallels of immune evasion by viruses and tumors, we propose that insights gained from anti-viral NK cell responses may serve as valuable lessons that can be leveraged for designing future cancer immunotherapies. This article is protected by copyright. All rights reserved.

Interferons (IFNs) are a group of signaling cytokines, secreted by host cells to induce protection against various disorders. IFNs can directly impact on tumor cells or indirectly induce the immune system to protect host cells. The expression levels of IFNs and its functions of are excellently modulated in a way to protect host cells from probable toxicities caused by extreme responses. The efficacy of anticancer therapies is correlated to IFNs signaling. Although IFN signaling is involved in induction of antitumor responses, chronic stimulation of the IFN signaling pathway can induce resistance to various antineoplasm therapies. Hence, IFNs are expressed by both cancer and immune cells, and modulate their biological function. Understanding this mechanism of action might be a key target of combination therapies.

The effect of interferon (IFN) on the replication of vaccinia DNA has been examined. Studies were carried out in infected mouse L cells grown in monolayer cultures. We examined discontinuous synthesis of small DNA fragments, ligation of the small fragments to form intermediate-sized DNA molecules, completion of unit-length DNA molecules, and introduction of crosslinks at each end of the newly replicated DNA molecules late in infection. We measured by pulse-label and pulse-chase experiments the extent of incorporation of 3H-thymidine into DNA and the conversion of small size DNA into mature and cross-linked viral DNA molecules. Interferon inhibited the initiation of viral DNA and this correlated with an overall inhibition of protein synthesis. Interferon inhibited elongation of viral DNA but this did not correlate with an inhibition of protein synthesis. The effect on elongation was not the result of increased degradation of newly synthesized DNA. It is suggested that the effects of IFN on initiation and elongation of vaccinia DNA may be the result of a decrease in the availability of enzymes or factors involved in the regulation of viral DNA synthesis.

Natural killer (NK) cells are non-B, non-T lymphoid cells of uncertain lineage that rapidly recognize and lyse a large variety of tumor or virus-infected cells, without the need for either prior sensitization or major histocompatibility complex (MHC)-dependent recognition. Though some essential problems in understanding NK cell function are still unsolved, considerable progress has been achieved in recent years following the identification of the characteristic large granular lymphocyte (LGL) morphology of NK cells and their purification, the study of their function at the single-cell level, and the cloning of mouse and human NK cell lines. Activated mainly by interferon (IFN), as well as important producers of IFN, NK cells appear to have a distinct role in immunoregulation in addition to their postulated major role in "immune surveillance," for which convincing in vivo data has accumulated. Future clinical applications may therefore include manipulations of the NK system through expansion and activation of patient's LGL or the use of cloned human NK cell lines.