Interferon-beta prevents the upregulation of interleukin-8 expression in human melanoma cells

Interferon-β decreases LPS-induced neutrophil recruitment to cardiac fibroblasts

Introduction: Cardiac fibroblasts (CF) are crucial cells in damaged heart tissues, expressing TLR4, IFN-receptor and responding to lipopolysaccharide (LPS) and interferon-β (IFN-β) respectively. While CF interact with immune cells; however, their relationship with neutrophils remains understudied. Additionally, theimpact of LPS and IFN-β on CF-neutrophil interaction is poorly understood. Methods: Isolated CF from adult rats were treated with LPS, with or without IFN-β. This study examined IL-8 secretion, ICAM-1 and VCAM-1 expression, and neutrophil recruitment, as well as their effects on MMPs activity. Results: LPS triggered increased IL-8 expression and secretion, along with elevated ICAM-1 and VCAM-1 expression, all of which were blocked by TAK-242. Pre-treatment with IFN-β countered these LPS effects. LPS treated CF showed higher neutrophil recruitment (migration and adhesion) compared to unstimulated CF, an effect prevented by IFN-β. Ruxolitinib blocked these IFN-β anti-inflammatory effects, implicating JAK signaling. Analysis of culture medium zymograms from CF alone, and CF-neutrophils interaction, revealed that MMP2 was mainly originated from CF, while MMP9 could come from neutrophils. LPS and IFN-β boosted MMP2 secretion by CF. MMP9 activity in CF was low, and LPS or IFN-β had no significant impact. Pre-treating CF with LPS, IFN-β, or both before co-culture with neutrophils increased MMP2. Neutrophil co-culture increased MMP9 activity, with IFN-β pre-treatment reducing MMP9 compared to unstimulated CF. Conclusion: In CF, LPS induces the secretion of IL-8 favoring neutrophils recruitment and these effects were blocked by IFN-. The results highlight that CF-neutrophil interaction appears to influence the extracellular matrix through MMPs activity modulation.

Interferons α and β in cancer: therapeutic opportunities from new insights

Over the past decade, preclinical and clinical research have confirmed the essential role of interferons for effective host immunological responses to malignant cells. Type I interferons (IFNα and IFNβ) directly regulate transcription of >100 downstream genes, which results in a myriad of direct (on cancer cells) and indirect (through immune effector cells and vasculature) effects on the tumour. New insights into endogenous and exogenous activation of type I interferons in the tumour and its microenvironment have given impetus to drug discovery and patient evaluation of interferon-directed strategies. When combined with prior observations or with other effective modalities for cancer treatment, modulation of the interferon system could contribute to further reductions in cancer morbidity and mortality. This Review discusses new interferon-directed therapeutic opportunities, ranging from cyclic dinucleotides to genome methylation inhibitors, angiogenesis inhibitors, chemoradiation, complexes with neoantigen-targeted monoclonal antibodies, combinations with other emerging therapeutic interventions and associations of interferon-stimulated gene expression with patient prognosis - all of which are strategies that have or will soon enter translational clinical evaluation.

Immunomodulatory and antitumor effects of type I interferons and their application in cancer therapy

During the last decades, the pleiotropic antitumor functions exerted by type I interferons (IFNs) have become universally acknowledged, especially their role in mediating interactions between the tumor and the immune system. Indeed, type I IFNs are now appreciated as a critical component of dendritic cell (DC) driven T cell responses to cancer. Here we focus on IFN-α and IFN-β, and their antitumor effects, impact on immune responses and their use as therapeutic agents. IFN-α/β share many properties, including activation of the JAK-STAT signaling pathway and induction of a variety of cellular phenotypes. For example, type I IFNs drive not only the high maturation status of DCs, but also have a direct impact in cytotoxic T lymphocytes, NK cell activation, induction of tumor cell death and inhibition of angiogenesis. A variety of stimuli, including some standard cancer treatments, promote the expression of endogenous IFN-α/β, which then participates as a fundamental component of immunogenic cell death. Systemic treatment with recombinant protein has been used for the treatment of melanoma. The induction of endogenous IFN-α/β has been tested, including stimulation through pattern recognition receptors. Gene therapies involving IFN-α/β have also been described. Thus, harnessing type I IFNs as an effective tool for cancer therapy continues to be studied.

The oncolytic virus dl922-947 reduces IL-8/CXCL8 and MCP-1/CCL2 expression and impairs angiogenesis and macrophage infiltration in anaplastic thyroid carcinoma

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human solid tumor and current treatments are ineffective in increasing patients' survival. Thus, the development of new therapeutic approaches for ATC is needed. We have previously shown that the oncolytic adenovirus dl922-947 induces ATC cell death in vitro and tumor regression in vivo. However, the impact of dl922-947 on the pro-tumorigenic ATC microenvironment is still unknown. Since viruses are able to regulate cytokine and chemokine production from infected cells, we sought to investigate whether dl922-947 virotherapy has such effect on ATC cells, thereby modulating ATC microenvironment. dl922-947 decreased IL-8/CXCL8 and MCP-1/CCL2 production by the ATC cell lines 8505-c and BHT101-5. These results correlated with dl922-947-mediated reduction of NF-κB p65 binding to IL8 promoter in 8505-c and BHT101-5 cells and CCL2 promoter in 8505-c cells. IL-8 stimulates cancer cell proliferation, survival and invasion, and also angiogenesis. dl922-947-mediated reduction of IL-8 impaired ATC cell motility in vitro and ATC-induced angiogenesis in vitro and in vivo. We also show that dl922-947-mediated reduction of the monocyte-attracting chemokine CCL2 decreased monocyte chemotaxis in vitro and tumor macrophage density in vivo. Interestingly, dl922-947 treatment induced the switch of tumor macrophages toward a pro-inflammatory M1 phenotype, likely by increasing the expression of the pro-inflammatory cytokine interferon-γ. Altogether, we demonstrate that dl922-947 treatment re-shape the pro-tumorigenic ATC microenvironment by modulating cancer-cell intrinsic factors and the immune response. An in-depth knowledge of dl922-947-mediated effects on ATC microenvironment may help to refine ATC virotherapy in the context of cancer immunotherapy.

Interferons and their stimulated genes in the tumor microenvironment

Constitutive expression of interferons (IFNs) and activation of their signaling pathways have pivotal roles in host responses to malignant cells in the tumor microenvironment. IFNs are induced by the innate immune system and in tumors through stimulation of Toll-like receptors (TLRs) and through other signaling pathways in response to specific cytokines. Although in the oncologic context IFNs have been thought of more as exogenous pharmaceuticals, the autocrine and paracrine actions of endogenous IFNs probably have even more critical effects on neoplastic disease outcomes. Through high-affinity cell surface receptors, IFNs modulate transcriptional signaling, leading to regulation of more than 2,000 genes with varying patterns of temporal expression. Induction of the gene products by both unphosphorylated and phosphorylated STAT1 after ligand binding results in alterations in tumor cell survival, inhibition of angiogenesis, and augmentation of actions of T, natural killer (NK), and dendritic cells. The interferon-stimulated gene (ISG) signature can be a favorable biomarker of immune response but, in a seemingly paradoxical finding, a specific subset of the full ISG signature indicates an unfavorable response to DNA-damaging interventions such as radiation. IFNs in the tumor microenvironment thus can alter the emergence, progression, and regression of malignancies.

Identification of interferon-beta-stimulated genes that inhibit angiogenesis in vitro

Interferons (IFNs) have proven antitumor activity against a variety of human malignancies, which may result, at least in part, from inhibition of angiogenesis. The objective of this study was to identify IFN-stimulated genes (ISGs) that played a role in mediation of angiogenic inhibition. IFN-beta was a more potent antiangiogenic agent compared to IFN-alpha2b (80% versus 20%, respectively) and suggests that IFNs inhibited angiogenesis by preventing endothelial cell differentiation, and not by direct antiproliferative effects. To identify ISGs that were key inhibitors of angiogenesis, we utilized an in vitro fibrin gel angiogenic assay which closely recapitulated the in vivo processes of angiogenesis. DNA microarray analysis of IFN-beta-treated endothelial cells in the fibrin gel assay identified 11 ISGs that were induced >10-fold during angiogenesis inhibition. Recombinant IP-10 inhibited angiogenesis in a dose-dependent fashion, but was a less effective inhibitor compared to IFN-beta, suggesting that additional ISGs are involved in inhibiting angiogenesis. ISG20 was upregulated by microarray analysis, but did not inhibit angiogenesis when overexpressed in human umbilical vein endothelial cells (HUVECs). However, a dominant negative mutant of ISG20 inhibited angiogenesis by 43%. Results suggest that IFN-induced angiogenic inhibition was likely mediated by multiple ISGs; our novel finding is that decreased exonuclease activity in HUVECs associated with expression of the ISG20 ExoII mutant inhibited angiogenesis.

Growth inhibitory effects of IFN-beta on human liver cancer cells in vitro and in vivo

We investigated the effects of interferon-beta (IFN-beta) on the growth of human liver cancer cells. The effects of IFN-beta with or without 5-fluorouracil (5-FU) on the proliferation of 13 liver cancer cell lines were investigated in vitro. Chronologic change in IFN-alpha receptor 2 (IFNAR-2) expression was monitored in hepatocellular carcinoma (HCC) cells (HAK-1B) cultured with IFN-beta. After HAK-1B cells were transplanted into nude mice, various doses of IFN-beta were administered, and the tumor volume, weight, histology, tumor blood vessel, and angiogenesis factor expression were examined. IFN-beta inhibited the growth of 11 cell lines with apoptosis in a dose-dependent and time-dependent manner. With IFN-beta, IFNAR-2 expression in HAK-1B cells was significantly downregulated from 6 to 12 h. IFN-beta induced a dose-dependent decrease in tumor volume and weight and a significant increase of apoptosis in the tumor. Both basic fibroblast growth factor (bFGF) and blood vessel number in the tumor decreased only in mice receiving the lowest dose (1000 IU) of IFN-beta. IFN-beta with 10 muM of 5-FU frequently induced synergistic antiproliferative effects. IFN-beta with or without 5-FU induces strong antitumor effects in HCC cells, and we conclude that IFN-beta is useful for the prevention and treatment of HCC.

Growth inhibitory effects of pegylated IFN alpha-2b on human liver cancer cells in vitro and in vivo

PURPOSE

We investigated the effects of pegylated IFN-alpha2b (PEG-IFN-alpha2b) on the growth of human liver cancer cells.

METHODS

The effect of PEG-IFN-alpha2b on the proliferation of 13 liver cancer cell lines was investigated in vitro. Chronological changes in growth and IFN-alpha receptor-2 (IFNAR-2) expression were monitored in hepatocellular carcinoma (HCC) cells (HAK-1B) cultured with PEG-IFN-alpha2b. After HAK-1B cells were transplanted into nude mice, various doses of PEG-IFN-alpha2b or IFN-alpha2b were administered, and tumor volume, weight, histology, and IFNAR-2 expression were examined.

RESULTS

PEG-IFN-alpha2b inhibited the growth of nine cell lines with apoptosis in a dose- and time-dependent manner. Continuous contact with PEG-IFN-alpha2b induced time-dependent growth inhibition and down-regulation of IFNAR-2 expression. PEG-IFN-alpha2b induced a dose-dependent decrease in tumor volume and weight, a significant increase of apoptotic cells, and a decrease in IFNAR-2 expression in the tumor. The clinical dose for chronic hepatitis C was also effective. The antitumor effect of PEG-IFN-alpha2b was significantly stronger than that of non-PEG-IFN-alpha2b in vivo.

CONCLUSIONS

Continuous contact with PEG-IFN-alpha2b induces strong antitumor effects and the down-regulation of IFNAR-2 in HCC cells. The data suggest potential clinical application of PEG-IFN-alpha2b for the prevention and treatment of HCC.

Involvement of RB gene family in tumor angiogenesis

Angiogenesis, the development of new blood vessels from pre-existing vessels, represents a fundamental step in tumor progression and metastatization. The induction of vasculature is required for growth of the tumor mass, to ensure an adequate supply of oxygen and metabolites to the tumor beyond a critical size. Tumor angiogenesis is a highly regulated process that is controlled physiologically by the tumor microenvironment and genetically by alteration of several oncogenes or tumor suppressor genes. We will focus on recent demonstrations regarding the involvement of the retinoblastoma family proteins (phosphorylated retinoblastoma (pRb), p107 and pRb2/p130) at different levels of the angiogenic process. pRb and its homologs can regulate the expression of pro- and antiangiogenic factors, such as the vascular endothelial growth factor, through an E2F-dependent mechanism. Moreover, pRb is able to modulate also the transcriptional activity of several angiogenesis-related factors like HIF-1, Id2 and Oct-1. pRb2/p130 is required for both differentiation and mobilization of bone marrow-derived endothelial cell precursors and endothelial sprouting from neighboring vessels. The involvement of the pRb pathway in the angiogenesis process has also been demonstrated by different cellular models expressing viral oncoproteins, like human papilloma virus. Moreover, some natural and synthetic compounds demonstrate their antiangiogenetic activity with a mechanism of action involving pRb. Finally, the possible prognostic value of immunohistochemical evaluation of pRb and/or pRb2/p130 expression can represent a useful tool for the characterization of the angiogenic phenotype of specific tumor histotypes.

Selective induction of interleukin-8 expression in metastatic melanoma cells by transforming growth factor-beta 1

Interleukin (IL)-8 and transforming growth factor (TGF)-beta1 are proangiogenic factors overexpressed in advanced human melanoma. We investigated the effects of TGF-beta1 on IL-8 expression in the well-characterized A375 human melanoma system. We demonstrated by enzyme-linked immunoassay and Northern blot analysis that TGF-beta1 selectively induced IL-8 expression, at both protein and mRNA levels, in highly metastatic A375SM cells but not cells of their poorly metastatic parental line A375P. Transient transfection with luciferase reporter gene constructs revealed that TGF-beta1 activated IL-8 promoter activity in A375SM cells but not A375P cells. Studies with progressive 5' deletion constructs and site-specific mutations demonstrated that a construct containing -133 to +44 of the 5'-flanking sequence was necessary and sufficient for maximal TGF-beta1-induced transcription response and that TGF-beta1-induced activation of IL-8 promoter depended on AP-1 (-126 to -120 bp), NF-kappaB (-94 to -71 bp), and C/EBP-like factor NF-IL6 (-94 to -81 bp) in this region. Interestingly, both A375P and A375SM cells expressed type I and type II TGF-beta receptors and TGF-beta1 induced the nuclear translocation of Smad3 protein in both A375P and A375SM cells. Moreover, both A375P and A375SM cells were susceptible to TGF-beta1-induced growth inhibition. Our data thus demonstrated that TGF-beta1 selectively induced IL-8 expression in highly metastatic A375SM melanoma cells. This TGF-beta1-induced IL-8 expression could be an amplification cascade responsible for overexpression of IL-8 in human melanoma and one of potential mechanisms by which TGF-beta1 promotes angiogenesis, growth, and metastasis of human melanoma.

Efficacy and tolerability of pegylated IFN-alpha in patients with neuroendocrine gastroenteropancreatic carcinomas

Interferon-alpha (IFN-alpha) is well established in the treatment of neuroendocrine carcinomas (NEC). Treatment is accompanied by fatigue and flu-like symptoms. In patients with chronic hepatitis C, pegylated IFN (PEGIFN) leads to improved antiviral efficacy and good tolerability. Our aim was to assess the efficacy and tolerability of PEG-IFN on the management of patients with well-differentiated NEC of the gastroenteropancreatic system. In 17 patients, the effect of PEG-IFN-alpha2b was studied. After first-line octreotide treatment, IFN-alpha was added at the time of tumor progression. Six patients were switched from conventional IFN-alpha, and 11 patients were IFN naive. Inhibition of tumor growth, including stabilization of disease, occurred in 13 of 17 patients, and biochemical and symptomatic responses were seen in 7 of 10 patients with functionally active tumors. Tolerability of PEG-IFN-alpha2b was much better than that of IFN-alpha. Fatigue occurred in 59% of all patients but was mild in severity. Eleven of thirteen patients who had a benefit remained on therapy for a median time of 20 months (range 6-30 months). PEG-IFN-alpha2b provides symptomatic and antiproliferative efficacy in patients with NEC. Better tolerability of PEG-IFN-alpha2b improved patients' compliance, justifying its use in patients who do not tolerate conventional IFN-alpha treatment.

Inducible nitric oxide synthase activity is essential for inhibition of prostatic tumor growth by interferon-beta gene therapy

We have previously reported that adenoviral vector-mediated interferon (IFN)-beta gene therapy inhibits orthotopic growth of human prostate cancer cells in nude mice. The purpose of this study was to determine efficacy and mechanisms of this therapy in immune-competent mice. TRAMP-C2Re3 mouse prostate cancer cells infected with 100 multiplicity of infection (MOI) of adenoviral vector encoding for mouse IFN-beta (AdmIFN-beta), but not AdE/1 (a control adenoviral vector), produced approximately 60 ng/10(5) cells/24 h of IFN-beta. The tumorigenicity of AdmIFN-beta-transduced cells was dramatically reduced in the prostates of C57BL/6 mice. A single intratumoral injection of 2 x 10(9) PFU (plaque-forming unit) of AdmIFN-beta inhibited tumor growth by 70% and prolonged survival of tumor-bearing mice. Intriguingly, this AdmIFN-beta therapy did not alter the growth of tumors in inducible nitric oxide synthase (iNOS)-null C57BL/6 mice. Immunohistochemical analysis revealed that treatment of tumors with AdmIFN-beta in wild-type C57BL/6 mice led to increased iNOS expression, decreased microvessel density, decreased cell proliferation, and increased apoptosis. Furthermore, quantitative reverse-transcriptional PCR analysis showed that AdmIFN-beta therapy, in C57BL/6 but not the iNOS-null counterparts, reduced levels of the mRNAs for angiopoietin, basic fibroblast growth factor, matrix metalloproteinase-9, transforming growth factor-beta1, vascular endothelial growth factor (VEGF)-A, and VEGF-B, as well as the antiapoptotic molecule endothelin-1. These data indicated that IFN-beta gene therapy could be effective alternative for the treatment of locally advanced prostate cancer and suggest an obligatory role of NO in IFN-beta antitumoral effects in vivo.

Review: Milstein Award lecture: interferons and cancer: where from here?

Interferons (IFNs) remain the most broadly active cytokines for cancer treatment, yet ones for which the full potential is not reached. IFNs have impacted positively on both quality and quantity of life for hundreds of thousands of cancer patients with chronic leukemia, lymphoma, bladder carcinoma, melanoma, and renal carcinoma. The role of the IFN system in malignant pathogenesis continues to enhance understanding of how the IFN system may be modulated for therapeutic advantage. Reaching the full potential of IFNs as therapeutics for cancer will also result from additional understanding of the genes underlying apoptosis induction, angiogenesis inhibition, and influence on immunologic function. Food and Drug Administration (FDA) approval of IFNs occurred less than 20 years ago; after 40 years, third-generation products of early cytotoxics, such as 5- fluorouracil (5FU), are beginning to reach clinical approval. Thus, substantial potential exists for additional application of IFNs and IFN inducers as anticancer therapeutics, particularly when one considers that their pleiotropic cellular and molecular effects have yet to be fully defined.

Antiproliferative effects of interferon-alphaCon1 on ovarian clear cell adenocarcinoma in vitro and in vivo

PURPOSE

We examined the antiproliferative effect of IFN-alphaCon1 and its mechanism on ovarian clear cell adenocarcinoma in vitro and in vivo.

EXPERIMENTAL DESIGN

(a) The effects of IFN-alphaCon1 on growth, morphology, cell cycle, and type I IFN-alpha receptor (IFNAR-2) expression were examined on two ovarian clear cell adenocarcinoma cell lines (KOC-5C and KOC-7C) in vitro. (b) KOC-5C or KOC-7C cells were transplanted into nude mice, and changes in tumor volume, tumor weight, apoptosis, necrosis, and microvessel density were investigated. The expression of angiogenesis factors was examined in the serum and the developed tumors.

RESULTS

Both cell lines expressed IFNAR-2 mRNA, but its protein was detected only in KOC-7C. In KOC-7C cells, antiproliferative effects were observed in a time- and dose-dependent manner and cell division was blocked at the S phase. The KOC-7C tumors showed decreases in tumor volume and weight; a decreasing tendency in basic fibroblast growth factor (bFGF), vascular endothelial growth factor, and interleukin (IL)-8 protein expression in the tumor; a significant decrease in bFGF and IL-8 protein expression in the serum, and of microvessel density; and significant increase in apoptosis and necrosis in the tumor. In the KOC-5C tumors, these in vitro and in vivo changes were not apparent, and the antiproliferative effects of IFN-alphaCon1 were not obvious.

CONCLUSIONS

IFN-alphaCon1 suppresses tumor proliferation by inducing apoptosis, blocking the cell cycle, and inhibiting tumor angiogenesis. Our findings show that the clinical efficacy of IFN-alphaCon1 can be predicted by examining IFNAR-2 expression on tumor cells, and the efficacy of IFN-alphaCon1 treatment can be evaluated by measuring serum bFGF and IL-8 levels.

The interferon-inducible IFI16 gene inhibits tube morphogenesis and proliferation of primary, but not HPV16 E6/E7-immortalized human endothelial cells

Immunohistochemical analysis has demonstrated that the human IFI16 gene, in addition to the hematopoietic tissues, is highly expressed in endothelial cells and squamous stratified epithelia. In this study, we have developed a reliable HSV-derived replication-defective vector (TO-IFI16) to efficiently transduce IFI16 into primary human umbilical vein endothelial cells (HUVEC), which are usually poorly transfectable. HUVEC infection with TO-IFI16 virus suppressed endothelial migration, invasion and formation of capillary-like structures in vitro. In parallel, sustained IFI16 expression inhibited HUVEC cell cycle progression, accompanied by significant induction of p53, p21, and hypophosphorylated pRb. Further support for the involvement of these pathways in IFI16 activity came from the finding that infection with TO-IFI16 virus does not impair the in vitro angiogenic activity and cell cycle progression of HUVEC immortalized by HPV16 E6/E7 oncogenes, which are known to inactivate both p53 and pRb systems. This use of a reliable viral system for gene delivery into primary human endothelial cells assigns a potent angiostatic activity to an IFN-inducible gene, namely IFI16, and thus throws further light on antiangiogenic therapy employing IFNs.

Molecular Pathogenesis of Vascular Anomalies: Classification into Three Categories Based upon Clinical and Biochemical Characteristics

Vascular tumors and malformations can be challenging to diagnose. Although they can resemble one another, their classification into tumors, such as hemangiomas of infancy, and malformations, such as venous or arteriovenous malformations, is based not only on their divergent biological behavior, but also on their pathogenesis. This review examines the molecular pathobiology of the processes involved in the development of these vascular birthmarks as they are currently understood. The terms hemangioma, hemangiosarcoma, and vascular proliferation are often used interchangeably, even though these entities are clinically and biochemically distinct. A more precise classification is necessary to facilitate communication between basic scientists and clinicians. Vasculogenesis, the in situ differentiation of blood vessels, occurs very early in the developing embryo. In vivo and in vitro studies, as well as knockout models, seem to indicate that this mechanism is unlikely to be involved in the development of either vascular malformations or hemangiomas of infancy. Recent advances in embryonic angiogenesis, especially explorations of mechanisms of vascular remodeling, have brought new understanding of the pathogenesis of vascular malformations. Vascular remodeling, an integral part of angiogenesis that centers upon the interactions between pericytes and endothelial cells, has been shown to be defective in certain experimental models and in some familial cases of vascular malformation. The occurrences of arteriovenous malformations in territories susceptible to increased remodeling also point towards epigenetic events in the development of vascular malformations.

Regulation of neoplastic angiogenesis

The progressive growth of neoplasms and the production of metastasis depend on the development of adequate vasculature, i.e., angiogenesis. The extent of angiogenesis is determined by the balance between positive- and negative-regulating molecules that are released by tumor and host cells in the microenvironment. The growth of many neoplasms is associated with the absence of the endogenous inhibitor of angiogenesis, interferon beta (IFN beta). A survey of multiple mouse and human tumors shows a lack of IFN beta associated with extensive angiogenesis. Therapy with IFN alpha or beta either by subcutaneous injection of the protein or by introduction of viral vectors that contain the IFN beta gene inhibit angiogenesis and, hence, progressive tumor growth.

Infection and cancer: the common vein

The role of infectious agents in the development of cancer is well documented. The pathogenesis of various human neoplasms ranging from non-Hodgkin lymphoma (NHL) to cervical carcinoma frequently involves a chronic, most often viral, infection. At the same time, there is compelling evidence that certain acute infections result in the inhibition of neoplastic growth. The basis for this phenomenon is often thought to be concomitant anti-tumor immunity. Yet, experimental data supporting this hypothesis are scarce, and other non-immune anti-tumor factors could be involved. For instance, since virtually all aggressive tumors outstrip their blood supply, development of new vessels, or angiogenesis, is a limiting factor during neoplastic growth. In this review, we will discuss recent studies that implicate anti-angiogenesis in infection-mediated tumor suppression and suggest that this mechanism could also complement cytotoxic immunity arising from the use of cancer vaccines.

Differential response of primary and metastatic melanomas to neutrophils attracted by IL-8

IL-8 is a strong chemoattractant for neutrophils, and it is constitutively produced by many tumors, including human melanomas. To determine the biologic importance of IL-8 for melanoma cells from primary and metastatic lesions, we transduced selected cell lines constitutively producing low levels of IL-8 with IL-8 cDNA using a replication-deficient adenoviral vector. Nontumorigenic SBcl2 primary melanoma cells formed tumors when transduced with increasing plaque-forming units of IL-8 per cell. However, at high IL-8 transduction levels (100 ng/ml/10(5) cells in 48 hr), tumor growth was impaired due to massive neutrophil infiltration. A similar biphasic response was observed in WM115 primary melanomas, which are tumorigenic but not metastatic. Depletion of neutrophils with an antibody that blocks the accumulation of granulocytes at the site of inflammation enabled transduced primary melanomas secreting high levels of IL-8 to survive and grow. In contrast, highly tumorigenic and metastatic 451Lu cells showed marked increases in tumor growth and number of metastatic foci in the lungs depending on the expression levels of IL-8. Cytotoxicity assays with isolated neutrophils confirmed the preferential killing of primary over metastatic melanoma cells. SBcl2 cells stimulated by IL-8 to form tumors in immunodeficient mice were induced to produce VEGF, suggesting that the angiogenic response is enhanced due to increased growth factor production. Our results demonstrate that nontumorigenic primary melanomas depend on IL-8 stimulation in vivo for growth and that tumor growth depends on the level of neutrophil infiltration. Metastatic melanomas proliferate in vivo independently of infiltrating neutrophils.

Interferons as antiangiogenic agents

Interferons (IFNs), pleiotropic cytokines that regulate antiviral, antitumor, apoptotic, and cellular immune responses, were the first endogenous antiangiogenic regulators identified. In a species-specific manner, IFNs inhibit secretion of such angiogenic factors as basic fibroblast growth factor from tumor cells. The antiangiogenic activity of IFNs is enhanced when they are combined with other antiangiogenic agents, such as tamoxifen and thalidomide.

Disturbance of tumor necrosis factor alpha-mediated beta interferon signaling in cervical carcinoma cells

In the present study we show that malignant human papillomavirus (HPV)-positive cells lost their ability to synthesize endogenous beta interferon (IFN-beta) upon tumor necrosis factor alpha (TNF-alpha) treatment. IFN-beta transcription, however, was reinducible in nonmalignant HPV-positive cells, which was confirmed in functional protection assays against encephalomyocarditis virus or vesicular stomatitis virus infections. Addition of neutralizing antibodies against IFN-beta blocked the antiviral effect, excluding the possibility that other IFN types were involved. Conversely, both malignant and immortalized cells could be protected against viral cytolysis when either IFN-beta, IFN-alpha, or IFN-gamma was added exogenously. This indicates that only the cross talk between TNF-alpha and the IFN-beta pathways, and not IFN-alpha/beta and IFN-gamma signaling in general, is perturbed in cervical carcinoma cells. Notably, full virus protection was restricted exclusively to nonmalignant cells, indicating that the antiviral effect correlates with the growth-inhibitory and virus-suppressive properties of TNF-alpha. The IFN-regulatory factors IRF-1 and p48 (ISGF3gamma) emerged as key regulatory molecules in the differential IFN-beta response, since their transcription was either absent or only inefficiently enhanced in tumorigenic cells upon treatment with TNF-alpha. Inducibility of both genes, however, became reestablished in cervical carcinoma cells, which were complemented to nontumorigenicity after somatic cell hybridization. Complementation was paralleled by the entire reconstitution of cytokine-mediated IFN-beta expression and the ability of TNF-alpha to exert an antiviral state. In contrast, under conditions where tumor suppression was not accomplished upon somatic cell hybridization, neither expression of IRF-1, p48, and IFN-beta nor antiviral activity could be restored.

Interleukin-8 and human cancer biology

The aggressive nature of metastatic human cancer has been shown to be related to numerous abnormalities in growth factors and their receptors. These perturbations confer a tremendous growth advantage to the malignant cells. Interleukin-8 (IL-8), originally discovered as a chemotactic factor for leukocytes, has recently been shown to contribute to human cancer progression through its potential functions as a mitogenic, angiogenic, and motogenic factor. While it is constitutively detected in human cancer tissues and established cell lines, IL-8 expression is regulated by various tumor microenvironment factors, such as hypoxia, acidosis, nitric oxide, and cell density. Understanding the mechanisms of both inducible and constitutive IL-8 expression will be helpful in designing potential therapeutic strategies of targeting IL-8 to control tumor growth and metastasis. In this review, the role and regulation of IL-8 expression in the growth and metastasis of human cancer with a focus on human pancreatic adenocarcinoma will be discussed.

Suppression of angiogenesis and therapy of human colon cancer liver metastasis by systemic administration of interferon-alpha

The purpose of this study was to determine whether systemic administration of interferon-alpha (IFN-alpha) can inhibit liver metastasis produced in nude mice by human colon cancer cells. KM12L4 (IFN-alpha-sensitive) or KM12L4 IFN(R) (IFN-alpha-resistant) cells were injected into the spleen of nude mice. Seven days later, the mice were treated with subcutaneous (s.c.) injections of IFN-alpha (70,000 units/week) at different dosing schedules (1, 2, or 7 times/week). Significant inhibition of tumor growth, vascularization and expression of basic fibroblast growth factor (bFGF) or matrix metalloproteinase-9 (MMP-9) mRNA and protein occurred in mice given daily injections of IFN-alpha. Kinetic analysis of therapy showed that daily s.c. administrations of 10,000 units of IFN-alpha induced apoptosis in liver metastasis-associated endothelial cells, followed by inhibition of tumor cell division and apoptosis of tumor cells. These data suggest that the antiangiogenic activity of IFN-alpha-2a depends on frequent administration of the optimal biologic dose.

A potential role for interleukin-8 in the metastatic phenotype of breast carcinoma cells

This study shows a strong correlation between the metastatic potentials of breast carcinoma cell lines and their ectopic expression of interleukin-8 (IL-8). Correlations exist for both constitutive and induced levels of IL-8 released. A correlation was also observed between cell morphology, metastatic potential, and IL-8 profile. Metastatic lines are fusiform in appearance, whereas, nonmetastatic lines are epithelioid. The metastatic potential of two breast carcinoma lines was examined using an orthotopic model of spontaneous metastasis. Metastatic cells formed rapidly growing, poorly differentiated primary tumors that metastasized. Nonmetastatic cells formed rapidly growing differentiated primary tumors that did not produce detectable metastases. Comparison of IL-8 expression by the parental cells and cell cultures developed from primary and metastatic tumors, demonstrates that IL-8 released by cultured cells from the primary tumor is higher than that of the parental cells, and IL-8 released by cultured cells derived from the metastatic lung tumors is greater than that released by cultured cells derived from the primary tumor. These data demonstrate a strong correlation between the metastatic phenotype of a cell and its IL-8 expression, suggesting a role for IL-8 in promoting the metastatic potential of breast tumor cells.

Immunological enhancement of primary tumor development and its prevention

While it has been known for decades that the growth of tumor transplants can be enhanced immunologically, the potential significance of these previous findings to the development of primary tumors and the mechanisms of tumor enhancement has remained obscure. This review will summarize recent experiments indicating that primary tumor development can be enhanced by active immunization. The evidence suggests that antibodies, B cells and CD4+ T cells can play a critical role in enhancing the development of primary, tumors, whereas endogenous interferon-gamma (IFNgamma) can counteract enhancement. Thus, we envision two possible functions of IFNgamma: (i) preventing B cell and antibody enhancement and (ii) counteracting tumor promotion independent of T and B cells.

Expression of interleukin-8 detected by in situ hybridization correlates with worse prognosis in primary cutaneous melanoma

Previous in vitro studies have demonstrated that endogenously produced human interleukin-8 (IL-8) can act as an important growth factor for human melanoma cells in vitro. The present study, has investigated whether IL-8 mRNA expression in primary melanomas may be of prognostic relevance with regard to melanoma progression and metastatic spread. In order to evaluate the clinical significance of IL-8 mRNA expression of melanoma cells in vivo, 59 melanocytic tissue specimens (37 primary melanomas and 22 melanocytic naevi) were studied using a semiquantitative in situ hybridization technique. Significant mRNA expression of IL-8 was found in 59 per cent (22/37) of melanomas. In 19 per cent (7/37) of the malignant melanomas, additional hybridization signals were noted within keratinocytes of the overlying epidermis. In contrast, paralesional normal-appearing epidermis and melanocytes in non-malignant lesions (melanocytic naevi) showed no IL-8 mRNA. Analysis of the relationship between IL-8 expression and clinico-histopathological features showed a significant association between IL-8 mRNA expression and the histological melanoma subtype (IL-8 mRNA: 14/19 in superficial spreading melanoma versus 4/12 in nodular melanoma, p< 0.05). Furthermore, IL-8 expression in primary tumours could be correlated with the patients' clinical course, with time to progression being significantly reduced in primary tumours expressing IL-8 in either the tumour cells or keratinocytes of the overlying epidermis. These results demonstrate for the first time that IL-8 expression, as detected by in situ hybridization in primary tumours, may serve as a significant prognostic factor for tumour progression in human malignant melanoma.

CXC-chemokines stimulate invasion and chemotaxis in prostate carcinoma cells through the CXCR2 receptor

BACKGROUND

Metastasis of prostate carcinoma requires invasion through the basement membrane, a thin extracellular matrix that underlies the epithelial cells, which must be breached by tumor cells invading into surrounding tissue. The CXC-chemokines, which have been shown to promote the migration of neutrophils and carcinoma cells, are candidates to influence prostate carcinoma-cell invasion.

METHODS

CXC-chemokines were examined for the ability to stimulate prostate cell line PC3 invasion in vitro through a reconstituted basement membrane and long-term migration and short-term adhesion to laminin, a major component of the basement membrane.

RESULTS

PC3 cells responded to IL-8 and GROalpha with a 1. 6-2-fold increase in invasion through reconstituted basement membrane. A corresponding 2-3-fold increase in chemotaxis toward IL-8 and GROa was seen on laminin. Anti-CXCR2 antibody inhibited IL-8-stimulated migration. Expression levels of the beta(1) integrins were not changed by IL-8, and alpha(6beta1) integrin was used for both stimulated and baseline migration. In addition to the increases in migration and invasion, 2-6-fold transient increases in adhesion on laminin were seen with both IL-8 and GROalpha.

CONCLUSIONS

These results suggest that the CXC-chemokines stimulate migration and invasion in part by altering the activation state of the beta(1) integrins. The CXC-chemokines act on prostate carcinoma cells through the CXCR2 receptor to promote behavior important for metastasis, and as such may be important in prostate carcinoma progression and metastasis.

Angiogenesis and growth of murine colon carcinoma are dependent on infiltrating leukocytes

We determined whether the angiogenesis and growth of murine colon carcinomas growing in the wall of the cecum is dependent on infiltrating leukocytes. Syngeneic BALB/c or SCID mice were treated with a myelosuppressive, maximally tolerated dose of doxorubicin. Parental or multidrug resistant CT-26 colon carcinoma cells were implanted into the cecal wall 3 days after the second intravenous injection of doxorubicin. Control mice developed large, well-vascularized tumors, whereas doxorubicin-pretreated mice did not. Intravenous injection of spleen cells from normal BALB/c or SCID mice one day prior to tumor cell implantation reversed the decreased vascularity and tumorigenicity. The production of proangiogenic molecules and microvessel density in tumors directly correlated with the number of infiltrating leukocytes, suggesting that tumor-infiltrating leukocytes are essential to angiogenesis of murine colon carcinomas.

Expression of interferon-beta is associated with growth arrest of murine and human epidermal cells

The cytokine interferon-beta is a regulator of cell replication and function, including invasion and induction of angiogenesis. The goal of this study was to determine whether the expression of interferon-beta by cells in the epidermis correlated with terminal differentiation. In situ hybridization analysis and immunohistochemical staining of formalin-fixed, paraffin-embedded specimens of normal human and murine epidermis and human and murine skin tumors of epithelial origin revealed that only differentiated, nondividing cells of the epidermis expressed interferon-beta protein. Keratinocyte cultures established from the epidermis of 3 d old mice were maintained under conditions permitting continuous cell division or induction of differentiation. Continuously dividing cells did not produce interferon-beta whereas nondividing differentiated cells expressing keratin 1 did. Growth-arrested, undifferentiated keratinocytes also expressed interferon-beta protein. Neutralizing interferon-beta in the culture medium inhibited differentiation, but the addition of exogenous interferon-beta did not stimulate differentiation. These data indicate that interferon-beta is produced by growth-arrested, terminally differentiated keratinocytes.