Cancer-associated fibroblasts downregulate type I interferon receptor to stimulate intratumoral stromagenesis

Activation of cancer-associated fibroblasts (CAFs) and ensuing desmoplasia play an important role in the growth and progression of solid tumors. Here we demonstrate that, within colon and pancreatic ductal adenocarcinoma tumors, efficient stromagenesis relies on downregulation of the IFNAR1 chain of the type I interferon (IFN1) receptor. Expression of the fibroblast activation protein (FAP) and accumulation of the extracellular matrix (ECM) was notably impaired in tumors grown in the Ifnar1S526A (SA) knock-in mice, which are deficient in IFNAR1 downregulation. Primary fibroblasts from these mice exhibited elevated levels of Smad7, a negative regulator of the transforming growth factor-β (TGFβ) pathway. Knockdown of Smad7 alleviated deficient ECM production in SA fibroblasts in response to TGFβ. Analysis of human colorectal cancers revealed an inverse correlation between IFNAR1 and FAP levels. Whereas growth of tumors in SA mice was stimulated by co-injection of wild type but not SA fibroblasts, genetic ablation of IFNAR1 in fibroblasts also accelerated tumor growth. We discuss how inactivation of IFNAR1 in CAFs acts to stimulate stromagenesis and tumor growth.

Activation of p38α stress-activated protein kinase drives the formation of the pre-metastatic niche in the lungs

Primary tumor-derived factors (TDFs) act upon normal cells to generate a pre-metastatic niche, which promotes colonization of target organs by disseminated malignant cells. Here we report that TDFs-induced activation of the p38α kinase in lung fibroblasts plays a critical role in the formation of a pre-metastatic niche in the lungs and subsequent pulmonary metastases. Activation of p38α led to inactivation of type I interferon signaling and stimulation of expression of fibroblast activation protein (FAP). FAP played a key role in remodeling of the extracellular matrix as well as inducing the expression of chemokines that enable lung infiltration by neutrophils. Increased activity of p38 in normal cells was associated with metastatic disease and poor prognosis in human melanoma patients whereas inactivation of p38 suppressed lung metastases. We discuss the p38α-driven mechanisms stimulating the metastatic processes and potential use of p38 inhibitors in adjuvant therapy of metastatic cancers.

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.

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.

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.

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.

Abstract A63: IFNAR1 downregulation during melanoma progression upregulates αv expression and promotes metastasis

The anti-metastatic effects of type 1 interferon (IFN1) prompted its use for adjuvant therapy in malignant melanoma patients at high risk for developing metastasis. While IFN1 adjuvant therapy continues to be the preferred treatment, many patients fail to elicit response to IFN1 treatment and progress to develop distal metastases often resulting in a lethal outcome. We observed downregulation of the IFNAR1 chain of the IFN1 receptor and suppression of IFN1 signaling in genetically engineered mouse melanomas driven by melanocyte-specific activation of Braf and inactivation of Pten. Induction of melanoma in animals expressing IFNAR1 that is deficient in ubiquitination and degradation led to a delayed onset of the disease and decreased number of local metastases. Remarkably, no distant metastases were found in these mice despite substantial primary tumor burden. Gene set enrichment analysis demonstrated a dramatic loss of the αv integrin pathway signature in mice harboring stabilized IFNAR1. Conversely, melanomas induced in Ifnar1 knockout mice yielded transplantable cell lines that displayed high levels of αv expression. Restoring IFNAR1 expression in these cells led to the loss of αv expression. We discuss the role of these mechanisms in melanoma metastasis and refractoriness to IFN1-based therapy.

Citation Format: Angelica Ortiz, Yuliya V. Katlinskaya, Kanstantsin V. Katlinski, Serge Y. Fuchs. IFNAR1 downregulation during melanoma progression upregulates αv expression and promotes metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Metastasis; 2015 Nov 30-Dec 3; Austin, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(7 Suppl):Abstract nr A63.

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.

DNA-damage-induced type I interferon promotes senescence and inhibits stem cell function

Expression of type I interferons (IFNs) can be induced by DNA-damaging agents, but the mechanisms and significance of this regulation are not completely understood. We found that the transcription factor IRF3, activated in an ATM-IKKα/β-dependent manner, stimulates cell-autonomous IFN-β expression in response to double-stranded DNA breaks. Cells and tissues with accumulating DNA damage produce endogenous IFN-β and stimulate IFN signaling in vitro and in vivo. In turn, IFN acts to amplify DNA-damage responses, activate the p53 pathway, promote senescence, and inhibit stem cell function in response to telomere shortening. Inactivation of the IFN pathway abrogates the development of diverse progeric phenotypes and extends the lifespan of Terc knockout mice. These data identify DNA-damage-response-induced IFN signaling as a critical mechanism that links accumulating DNA damage with senescence and premature aging.

Triggering ubiquitination of IFNAR1 protects tissues from inflammatory injury

Type 1 interferons (IFN) protect the host against viruses by engaging a cognate receptor (consisting of IFNAR1/IFNAR2 chains) and inducing downstream signaling and gene expression. However, inflammatory stimuli can trigger IFNAR1 ubiquitination and downregulation thereby attenuating IFN effects in vitro. The significance of this paradoxical regulation is unknown. Presented here results demonstrate that inability to stimulate IFNAR1 ubiquitination in the Ifnar1(SA) knock-in mice renders them highly susceptible to numerous inflammatory syndromes including acute and chronic pancreatitis, and autoimmune and toxic hepatitis. Ifnar1(SA) mice (or their bone marrow-receiving wild type animals) display persistent immune infiltration of inflamed tissues, extensive damage and gravely inadequate tissue regeneration. Pharmacologic stimulation of IFNAR1 ubiquitination is protective against from toxic hepatitis and fulminant generalized inflammation in wild type but not Ifnar1(SA) mice. These results suggest that endogenous mechanisms that trigger IFNAR1 ubiquitination for limiting the inflammation-induced tissue damage can be purposely mimicked for therapeutic benefits.