Serum imbalance of cytokines in melanoma patients

Helper Innate Lymphoid Cells-Unappreciated Players in Melanoma Therapy

Immune checkpoint inhibitors (ICIs) and targeted therapy have dramatically changed the outcome of metastatic melanoma patients. Although immune checkpoints were developed based on the biology of adaptive T cells, they have subsequently been shown to be expressed by other subsets of immune cells. Similarly, the immunomodulatory properties of targeted therapy have been studied primarily with respect to T lymphocytes, but other subsets of immune cells could be affected. Innate lymphoid cells (ILCs) are considered the innate counterpart of T lymphocytes and include cytotoxic natural killer cells, as well as three helper subsets, ILC1, ILC2 and ILC3. Thanks to their tissue distribution and their ability to respond rapidly to environmental stimuli, ILCs play a central role in shaping immunity. While the role of NK cells in melanoma physiopathology and therapy is well established, little is known about the other helper ILC subsets. In this review, we summarize recent findings on the ability of the melanoma TME to influence the phenotype and functional plasticity of helper ILCs and highlight how this subset may in turn shape the TME. We also discuss changes in the melanoma TME induced by targeted therapy that could affect helper ILC functions, the expression of immune checkpoints on this subset and how their inhibition by ICIs may modulate helper ILC function and contribute to therapeutic efficacy.

Saffron anti-metastatic properties, ancient spice novel application

Crocus sativus L. (saffron), was applied as a spice, food colorant and medicine since four millennia ago and has been used as a remedy for various maladies. In the last three decades, the anti-primary tumor properties of saffron and its main carotenoids, crocin and crocetin, have been well explored. Despite the fact that metastasis is the leading cause of death in cancer patients, the anti-metastatic potential of saffron and its carotenoids has been surveyed only this decade. This review aims to provide an unprecedented overview of the anti-metastatic effects of saffron, crocin and crocetin, and the mechanisms underlying these effects. Investigations on various cancers demonstrated the anti-migratory, anti-invasion, anti-angiogenic potentials of saffron and its carotenoids, as well as their effects suppressing cell-ECM adhesion and enhancing cell-cell attachment. Saffron and its carotenoids exert their impact through different mechanisms such as reduction of CD34 and suppression of Wnt/β-catenin, Ras/ERK, P38, DCLK1, EMT, matrix metalloproteinases and urokinases. Crocin displayed more effective anti-metastatic potency, in comparison with saffron extract and crocetin. The bioaccessibility/bioavailability, nontoxicity on normal cells, confirmed anti-tumor efficiency and the recent evidence on the anti-metastatic potential of saffron and its carotenoids, recommends them as a propitious multipotent dietary agent and herbal medicine.

Insights into Differentiation of Melanocytes from Human Stem Cells and Their Relevance for Melanoma Treatment

Simple Summary

The reactivation of embryonic developmental programs is crucial for melanoma cells to grow and to metastasize. In order to understand this process better, we first summarize the melanocytic differentiation process both in vivo and in vitro. Secondly, we compare and highlight important similarities between neural crest cell fate during differentiation and tumor cell characteristics during melanoma mestastasis. Finally, we suggest possible therapeutic targets, which could be used to inhibit phenotype switching by developmental cues and hence also suppress the metastatic melanoma spread.

Abstract

Malignant melanoma represents a highly aggressive form of skin cancer. The metastatic process itself is mostly governed by the so-called epithelial mesenchymal transition (EMT), which confers cancer cells migrative, invasive and resistance abilities. Since EMT represents a conserved developmental process, it is worthwhile further examining the nature of early developmental steps fundamental for melanocyte differentiation. This can be done either in vivo by analyzing the physiologic embryo development in different species or by in vitro studies of melanocytic differentiation originating from embryonic human stem cells. Most importantly, external cues drive progenitor cell differentiation, which can be divided in stages favoring neural crest specification or melanocytic differentiation and proliferation. In this review, we describe ectopic factors which drive human pluripotent stem cell differentiation to melanocytes in 2D, as well as in organoid models. Furthermore, we compare developmental mechanisms with processes described to occur during melanoma development. Finally, we suggest differentiation factors as potential co-treatment options for metastatic melanoma patients.

Serum proteomic analysis of melanoma patients with immunohistochemical profiling of primary melanomas and cultured cells: Pilot study

The steadily increasing incidence of malignant melanoma (MM) and its aggressive behaviour makes this tumour an attractive cancer research topic. The tumour microenvironment is being increasingly recognised as a key factor in cancer biology, with an impact on proliferation, invasion, angiogenesis and metastatic spread, as well as acquired therapy resistance. Multiple bioactive molecules playing cooperative roles promote the chronic inflammatory milieu in tumours, making inflammation a hallmark of cancer. This specific inflammatory setting is evident in the affected tissue. However, certain mediators can leak into the systemic circulation and affect the whole organism. The present study analysed the complex inflammatory response in the sera of patients with MM of various stages. Multiplexed proteomic analysis (Luminex Corporation) of 31 serum proteins was employed. These targets were observed in immunohistochemical profiles of primary tumours from the same patients. Furthermore, these proteins were analysed in MM cell lines and the principal cell population of the melanoma microenvironment, cancer‑associated fibroblasts. Growth factors such as hepatocyte growth factor, granulocyte‑colony stimulating factor and vascular endothelial growth factor, chemokines RANTES and interleukin (IL)‑8, and cytokines IL‑6, interferon‑α and IL‑1 receptor antagonist significantly differed in these patients compared with the healthy controls. Taken together, the results presented here depict the inflammatory landscape that is altered in melanoma patients, and highlight potentially relevant targets for therapy improvement.

The bidirectional crosstalk between metastatic uveal melanoma cells and hepatic stellate cells engenders an inflammatory microenvironment

Uveal melanoma is the most common primary ocular neoplasm in adults. It is peculiar for its hematogenous dissemination and its high propensity to spread to the liver. Current treatments rarely prolong patient survival. We hypothesized that metastatic uveal melanoma cells modulate the function of surrounding hepatic stellate cells to facilitate their own growth and survival. This study was conducted to investigate the role of the hepatic microenvironment on uveal melanoma aggressiveness. We demonstrated that the paracrine signaling of surrounding hepatic stellate cells have more transcriptional impact on metastatic uveal melanoma cells. Upregulated transcripts were linked to inflammation and included several interleukins. The uveal melanoma-stellate cell crosstalk induced as well the expression of transmembrane integrins. In addition, the interleukin-6 receptor inhibitor Tocilizumab did not reduce the growth of uveal melanoma cells. Our results provide evidence that inflammatory mediators are key players in the homing of uveal melanoma cells to the liver. The bidirectional crosstalk between uveal melanoma cells and hepatic stellate cells involved pro-fibrogenic interleukins. The inflammatory characteristics of the metastatic microenvironment might offer relevant therapeutic opportunities in uveal melanoma.

Proteomic profiles by multiplex microsphere suspension array

Advances in high-throughput proteomic approaches have provided substantial momentum to novel disease-biomarker discovery research and have augmented the quality of clinical studies. Applications based on multiplexed microsphere suspension array technology are making strong in-roads into the clinical diagnostic/prognostic practice. Conventional proteomic approaches are designed to discover a broad set of proteins that are associated with a specific medical condition. In comparison, multiplex microsphere immunoassays use quantitative measurements of selected set(s) of specific/particular molecular markers such as cytokines, chemokines, pathway signaling or disease-specific markers for detection, metabolic disorders, cancer, and infectious agents causing human, plant and animal diseases. This article provides a foundation to the multiplexed microsphere suspension array technology, with an emphasis on the improvements in the technology, data analysis approaches, and applications to translational and clinical research with implications for personalized and precision medicine.

Dietary Crocin Reverses Melanoma Metastasis

Crocus sativus and its bioactive constituent crocin are well known for anti-tumor potential in different models. However, the efficacy of crocin on in-vivo melanoma metastasis is not yet reported. In this study, melanoma metastatic model was developed by tail vein injection of B16F-10 cells in to C57BL/6 mice. Metastatic mice treated with two different doses of crocin (250 and 500 µg/kg of bodyweight) for 10 days and parameters such as lung metastasis inhibition, mean survival time, lung hydroxyproline, uronic acid and hexosamine levels were analyzed after 21 days of treatment. Then blood was collected and serum gamma glutamyl transpeptidase (g-GGT), sialic acid, tumor necrosis factor alpha (TNF-a), interleukin 10 (IL-10), IL-6, IL-2, and TIMP-1 levels were measured. Further, a lung histological examination was done in crocin treated metastatic mice. Subsequently hallmark metastatic parameters such as matrix metalloproteases (MMPs), extracellular regulated kinase 2 (ERK2), vascular endothelial growth factor (VEGF), and K-ras gene expression were investigated in the lungs of crocin treated metastatic mice. Further, in-vitro adhesion, invasion and migration of B16F-10 cells were examined after 24 h of crocin (5 and 10 µg/mL) treatment. Administration of crocin to tumor bearing C57BL/6 mice reduced the lung metastasis by 85%. Elevated levels of hydroxyproline, uronic acid, hexosamine, serum sialic acid andg-GGT in metastatic control were found to be significantly reduced in crocin treated mice. Crocin also inhibited expression of MMP-2, MMP-9, ERK-2, K-ras, and VEGF. Crocin reduced the ability of B16F-10 cells invasion (p<0.05), migration (p<0.05) and adhesion by upregulating E-cadherin expression. In conclusion, crocin elicited marked anti-metastatic potential by regulating the metastasis induced biomarkers.

Cancer Immune Equilibrium and Schizophrenia Have Similar Interferon-γ, Tumor Necrosis Factor-α, and Interleukin Expression: A Tumor Model of Schizophrenia

For at least a century, a debate has continued as to whether cancer risk is reduced in schizophrenia. Genetic studies have also suggested the 2 conditions may share protein transcriptional pathways. The author predicted that if the pathophysiology of schizophrenia confers protection from cancer, then the immunology of schizophrenia should reflect a state of tumor suppression, ie, the opposite of tumor escape. To examine this possibility, the author performed a literature search for measurements of cytokines in drug-naïve first episode subjects with schizophrenia for comparison with cytokine expression in tumor escape vs tumor suppression. The comparison showed that instead of either tumor suppression or escape, schizophrenia appears to be in a state of tumor equilibrium. Based on this finding, the author hypothesized that the clinical presentation of schizophrenia may involve cell transformation similar to an early stage of cancer initiation or an attenuated tumorigenesis. While this condition could reflect the presence of an actual tumor such as an ovarian teratoma causing anti-NMDA receptor encephalitis, it would only explain a small percentage of cases. To find a more likely tumor model, the author then compared the cytokine profile of schizophrenia to individual cancers and found the best match was melanoma. To demonstrate the viability of the theory, the author compared the hallmarks, emerging hallmarks, and enabling characteristics of melanoma to schizophrenia and found that many findings in schizophrenia are understood if schizophrenia is a condition of attenuated tumorigenesis.

Integrated analysis of multidimensional omics data on cutaneous melanoma prognosis

Multiple types of genetic, epigenetic, and genomic changes have been implicated in cutaneous melanoma prognosis. Many of the existing studies are limited in analyzing a single type of omics measurement and cannot comprehensively describe the biological processes underlying prognosis. As a result, the obtained prognostic models may be less satisfactory, and the identified prognostic markers may be less informative. The recently collected TCGA (The Cancer Genome Atlas) data have a high quality and comprehensive omics measurements, making it possible to more comprehensively and more accurately model prognosis. In this study, we first describe the statistical approaches that can integrate multiple types of omics measurements with the assistance of variable selection and dimension reduction techniques. Data analysis suggests that, for cutaneous melanoma, integrating multiple types of measurements leads to prognostic models with an improved prediction performance. Informative individual markers and pathways are identified, which can provide valuable insights into melanoma prognosis.

Melanoma-derived IL-1 converts vascular endothelium to a proinflammatory and procoagulatory phenotype via NFκB activation

Spreading of melanoma is associated with efficient extravasation of circulating tumor cells from the vascular system into distant target organs. This process is accompanied and supported by proinflammatory and procoagulatory conditions. In this study, we analysed the ability of human melanoma cell lines to activate endothelial cells (ECs) in vitro. Some melanoma cells, that is, MV3, were shown to trigger an prompt calcium-flux-dependent, procoagulatory endothelial response that was accompanied by luminal release of ultra-large von Willebrand factor (ULVWF) fibres that were immobilized to the endothelial surface layer. In contrast to MV3-derived supernatant, prolonged treatment of ECs with WM9-derived supernatant mediated a pronounced activation of nuclear factor kappa B (NFκB). NFκB activation in ECs was dependent on both IL-1α and IL-1β secreted from melanoma cells. Melanoma-derived IL-1 mediated an upregulation of proinflammatory cytokines IL-6 and IL-8, the intercellular adhesion molecule-1 (ICAM-1), the vascular cell adhesion molecule-1 (VCAM-1) and the procoagulatory tissue factor (TF) in ECs. Our data show that melanoma cells activate ECs either directly and within seconds or by an IL-1-mediated NFκB activation. Both pathways of EC activation convert the regular repressive function of ECs on inflammation and coagulation to a proinflammatory and procoagulatory surface that supports tumor progression.

In vivo profiling reveals immunomodulatory effects of sorafenib and dacarbazine on melanoma

Sorafenib is a multi-kinase inhibitor used alone or in combination with dacarbazine to treat metastasized melanoma. Our study investigated the relationship between metabolic response assessed by PET-CT and global transcriptome changes during sorafenib and dacarbazine therapy in patients with advanced melanoma. We conducted an open-label, investigator-initiated study that enrolled 13 sorafenib-naïve Stage IV melanoma patients, whose metastases were accessible for repeated biopsies. Treatment regimen included orally administered sorafenib and intravenous dacarbazine. Biopsies of skin or superficial lymph node metastases were taken before treatment (baseline), during sorafenib and after dacarbazine therapy and used for transcriptional profiling and validation experiments. Serum samples were evaluated for cytokine production. Metabolic response to therapy was observed in 45.5% of patients. The study drugs were well tolerated. We observed a clear upregulation of interferon (IFN)-stimulated immune response genes in profiled metastases. The IFNγ-induced gene signature seemed to be enhanced after addition of dacarbazine to sorafenib. Serum IFNγ also increased during therapy, particularly after addition of dacarbazine. Induction of IFNγ stimulated genes correlating with increased serum IFNγ was predictive of better clinical outcome and responders who had significantly higher serum IFNγ levels lived longer. Our data reveal in situ changes in melanoma metastases during treatment with sorafenib and dacarbazine and suggest an additional mechanism of action through immunomodulation.

Increased frequencies of CD11b(+) CD33(+) CD14(+) HLA-DR(low) myeloid-derived suppressor cells are an early event in melanoma patients

Myeloid-derived suppressor cells (MDSC) are a heterogeneous cell population characterized by immunosuppressive activity. Elevated levels of MDSC in peripheral blood are found in inflammatory diseases as well as in malignant tumors where they are supposed to be major contributors to mechanisms of tumor-associated tolerance. We investigated the frequency and function of MDSC in peripheral blood of melanoma patients and observed an accumulation of CD11b(+) CD33(+) CD14(+) HLA-DR(low) MDSC in all stages of disease (I-IV), including early stage I patients. Disease progression and enhanced tumor burden did not result in a further increase in frequencies or change in phenotype of MDSC. By investigation of specific MDSC-associated cytokines in patients' sera, we found an accumulation of IL-8 in all stages of disease. T-cell proliferation assays revealed that MDSC critically contribute to suppressed antigen-specific T-cell reactivity and thus might explain the frequently observed transient effects of immunotherapeutic strategies in melanoma patients.

Insights into the Transforming Growth Factor-β Signaling Pathway in Cutaneous Melanoma

Transforming growth factor-β (TGF-β) is a pleiotropic growth factor with broad tissue distribution that plays critical roles during embryonic development, normal tissue homeostasis, and cancer. While its cytostatic activity on normal epithelial cells initially defined TGF-β signaling as a tumor suppressor pathway, there is ample evidence indicating that TGF-β is a potent pro-tumorigenic agent, acting via autocrine and paracrine mechanisms to promote peri-tumoral angiogenesis, together with tumor cell migration, immune escape, and dissemination to metastatic sites. This review summarizes the current knowledge on the implication of TGF-β signaling in melanoma.

TNF-α and tumor lysate promote the maturation of dendritic cells for immunotherapy for advanced malignant bone and soft tissue tumors

BACKGROUND

Dendritic cells (DCs) play a pivotal role in the immune system. There are many reports concerning DC-based immunotherapy. The differentiation and maturation of DCs is a critical part of DC-based immunotherapy. We investigated the differentiation and maturation of DCs in response to various stimuli.

METHODS

Thirty-one patients with malignant bone and soft tissue tumors were enrolled in this study. All the patients had metastatic tumors and/or recurrent tumors. Peripheral blood mononuclear cells (PBMCs) were suspended in media containing interleukin-4 (IL-4) and granulocyte-macrophage colony stimulating factor (GM-CSF). These cells were then treated with or without 1) tumor lysate (TL), 2) TL + TNF-α, 3) OK-432. The generated DCs were mixed and injected in the inguinal or axillary region. Treatment courses were performed every week and repeated 6 times. A portion of the cells were analyzed by flow cytometry to determine the degree of differentiation and maturation of the DCs. Serum IFN-γ and serum IL-12 were measured in order to determine the immune response following the DC-based immunotherapy.

RESULTS

Approximately 50% of PBMCs differentiated into DCs. Maturation of the lysate-pulsed DCs was slightly increased. Maturation of the TL/TNF-α-pulsed DCs was increased, commensurate with OK-432-pulsed DCs. Serum IFN-γ and serum IL-12 showed significant elevation at one and three months after DC-based immunotherapy.

CONCLUSIONS

Although TL-pulsed DCs exhibit tumor specific immunity, TL-pulsed cells showed low levels of maturation. Conversely, the TL/TNF-α-pulsed DCs showed remarkable maturation. The combination of IL-4/GM-CSF/TL/TNF-α resulted in the greatest differentiation and maturation for DC-based immunotherapy for patients with bone and soft tissue tumors.

Induction of monocyte chemoattractant protein-1 and interleukin-10 by TGFbeta1 in melanoma enhances tumor infiltration and immunosuppression

Melanoma progression is associated with the expression of different growth factors, cytokines, and chemokines. Because TGFβ1 is a pleiotropic cytokine involved not only in physiologic processes but also in cancer development, we analyzed in A375 human melanoma cells, the effect of TGFβ1 on monocyte chemoattractant protein-1 (MCP-1) and interleukin-10 (IL-10) expression, two known factors responsible for melanoma progression. TGFβ1 increased the expression of MCP-1 and IL-10 in A375 cells, an effect mediated by the cross-talk between Smad, PI3K (phosphoinositide 3-kinase)/AKT, and BRAF-MAPK (mitogen activated protein kinase) signaling pathways. Supernatants from TGFβ1-treated A375 cells enhanced MCP-1-dependent migration of monocytes, which, in turn, expressed high levels of TGF,β1, bFGF, and VEGF mRNA. Moreover, these supernatants also inhibited functional properties of dendritic cells through IL-10-dependent mechanisms. When using in vitro, the TGFβ1-blocking peptide P144, TGFβ1-dependent Smad3 phosphorylation, and expression of MCP-1 and IL-10 were inhibited. In vivo, treatment of A375 tumor-bearing athymic mice with P144 significantly reduced tumor growth, associated with a lower macrophage infiltrate and decreased intratumor MCP-1 and VEGF levels, as well as angiogenesis. Finally, in C57BL/6 mice with B16-OVA melanoma tumors, when administered with immunotherapy, P144 decreased tumor growth and intratumor IL-10 levels, linked to enhanced activation of dendritic cells and natural killer cells, as well as anti-OVA T-cell responses. These results show new effects of TGFβ1 on melanoma cells, which promote tumor progression and immunosuppression, strongly reinforcing the relevance of this cytokine as a molecular target in melanoma.

The invasive potential of human melanoma cell lines correlates with their ability to alter fibroblast gene expression in vitro and the stromal microenvironment in vivo

The tumor microenvironment is thought to play an important role in invasion and metastasis. Previously, we have shown that signaling from melanoma cells can alter the gene expression profiles of fibroblasts in vitro and in vivo. To investigate whether the capacity to signal fibroblasts and alter host gene expression profiles is correlated to the invasive potential of specific human melanoma cell lines, we assayed changes in gene expression of fibroblasts when cocultured with the human melanoma cell lines BLM, MV3, A2058, SK-mel28 and WM164. Results indicated that the gene expression of key chemokines and cytokines, such as IL-1B, IL-8, IL-6 and CCL2/MCP1, was significantly upregulated in fibroblasts cocultured with the invasive melanoma lines BLM and MV3 compared to fibroblasts cocultured with noninvasive WM164 cells. The results were verified by quantitative RT-PCR as well as by protein assay and supported by immunohistochemistry of human invasive melanoma. Furthermore, a role for fibroblast-secreted IL-1B in the invasion of melanoma was demonstrated in vitro, where siRNA silencing of IL-1B in melanoma-stimulated fibroblasts resulted in a diminution of melanoma invasion. Although CCL2/MCP1, a chemoattractant for macrophages, was shown to be upregulated in fibroblasts cocultured with metastatic melanoma cell lines, immunohistochemical analysis of human melanoma also indicated CCL2/MCP1 production associated with the melanoma. In summary, these experiments indicate that the invasiveness of melanoma can partly be correlated to its ability to stimulate host stromal fibroblasts to give rise to the secretion of chemokines that generate a microenvironment that is conductive for melanoma invasion and metastasis.

Melanoma inhibition by cyclooxygenase inhibitors: role of interleukin-6 suppression, a putative mechanism of action, and clinical implications

Melanoma progression is often associated with supranormal levels of interleukin-6 (IL-6). Il-6 is an important growth factor for many cases of melanoma. A recent case report by Lejeune et al. [Melanoma Res 2006;16:263-265] of remission of an advanced melanoma during treatment with the cyclooxygenase, (COX) inhibitor rofecoxib can be explained by rofcoxib-mediated lowering of tumor-produced Il-6. Several examples of rofecoxib's ability to lower Il-6 in humans have been published recently in other settings, and many reports indicate that other commonly used COX inhibitors like aspirin, diclofenac, etodolac, indomethacin, naproxen, and many others, also lower Il-6 in humans. These studies are reviewed. The likely mechanism of COX inhibition leading to Il-6 lowering is due to the tendency for Il-6 levels to be controlled by intracellular cyclic adenosine monophosphate (cAMP). Adenylate cyclase is the rate-limiting enzyme in cAMP synthesis. Because adenylate cyclase activity is allosterically enhanced when it binds prostaglandin E, the latter increases Il-6. COX inhibition lowers prostaglandin E levels. This lowers intracellular cAMP levels. Lower cAMP results in lower Il-6 synthesis, lower levels of a required growth factor. Controlled studies are needed to define the role of COX inhibitors in melanoma treatment.

Basal level and behaviour of cytokines in a randomized outpatient trial comparing chemotherapy and biochemotherapy in metastatic melanoma

Cytokines play a crucial role in the host's immune response. In melanoma patients, cytokine profiles seems to be related to the clinical course and their imbalance could be associated to tumour progression. Thus, we studied a panel of baseline cytokines and their behaviour during treatment in order to verify their correlation with clinical outcomes. Interleukin-6, interleukin-8, interleukin-10, interleukin-12 and soluble receptor of interleukin-2 were evaluated in 90 out of 176 metastatic melanoma patients enrolled in a phase III study comparing chemotherapy and biochemotherapy. We divided patients into three different groups according to their own cytokine levels (low, intermediate and high) and then we correlated these groups with some clinical features. We also monitored the cytokines during the treatment in a subgroup of 37 patients. In univariate analysis, higher values of interleukin-6 (P = 0.005), soluble receptor of interleukin-2 (P = 0.001) and interleukin-12 (P = 0.010) were correlated with a worse survival. Conversely, interleukin-8 was unable to discriminate patients with different prognoses, and interleukin-10 was undetectable in the majority of patients. In multivariate analysis, only soluble receptor of interleukin-2 maintained its independent role in survival. The impact of baseline cytokines on response was insignificant. Regarding the behaviours of cytokines during treatment, the most remarkable aspect was a progressive increase of interleukin-12 and soluble receptor of interleukin-2 in patients with a better survival. In our metastatic melanoma patients, higher basal levels of interleukin-6, interleukin-12 and soluble receptor of interleukin-2 were associated with a worse survival. In contrast, a progressive increase of interleukin-12 and soluble receptor of interleukin-2 was observed during treatment in patients with a better survival.

Interleukin-6, secreted by human ovarian carcinoma cells, is a potent proangiogenic cytokine

Angiogenesis, a key rate-limiting step in the growth and dissemination of malignant tumors, is regulated by the balance between positive and negative effectors. Recent studies indicate that the pleiotropic cytokine interleukin-6 (IL-6) may contribute to the vascularization of some tumors by disrupting the equilibrium between positive and negative angiogenic regulatory molecules. We determined whether IL-6 participates in the angiogenesis observed during the progression of ovarian carcinoma. We measured IL-6 production by human ovarian cancer cell lines in vitro and in vivo. Not all cell lines secreted IL-6 in vitro; however, when the cell lines were implanted into the peritoneal cavity of female nude mice, every line secreted IL-6. Most human ovarian carcinoma cell lines tested secreted significant levels of the soluble IL-6 receptor (sIL-6R). Endothelial cell lines established from the ovary and mesentery of female H-2K(b)-tsA58 mice were tested for response to IL-6. Both endothelial cell lines expressed the IL-6R and their stimulation with the exogenous ligand significantly enhanced cell migration and activated the downstream signaling molecule signal transducers and activators of transcription 3. Dual immunohistochemical staining for IL-6R and CD31 revealed IL-6R expression on human endothelial cells within normal ovary and carcinoma specimens. Gelfoam sponges containing 0.4% agarose and IL-6 or basic fibroblast growth factor and implanted into the subcutis of BALB/c mice were vascularized to the same extent. Collectively, the data indicate that ovarian tumor cells secreted IL-6, a highly angiogenic cytokine that supports progression of disease.

Secretion of interleukin-6 and prostaglandin E2 during uveal melanoma-monocyte in vitro interactions

Host-tumor interactions in uveal melanoma are not well understood. It is believed that the cytokine interleukin-6 and the lipid mediator autacoid prostaglandin E2 are involved in tumor growth, proliferation, tumor cell survival, and angiogenesis. These cytokines have been shown to be poor prognostic markers in uveal and cutaneous melanoma. In this study, we investigated the levels of interleukin-6 and prostaglandin E2 in monocyte and uveal melanoma conditioned medium. Five human uveal melanoma cell lines (92.1, MKT-BR, OCM-1, SP6.5 and UW-1), and one monocyte cell line (28SC) were seeded in 6 well plates at a concentration of 1 x 10(6)cells ml(-1). After 18 hr melanoma conditioned medium was placed on the monocyte cell line and monocyte conditioned medium was placed on each uveal melanoma cell line. Tumor cells and monocytes incubated in fresh medium after 18 hr were used as controls. Interleukin-6 and prostaglandin E2 levels were determined by immunoassays prior to media transfer and 6, 12, 24, and 36 hr thereafter. In the absence of conditioned medium, neither product showed baseline levels of expression. Interleukin-6 but not prostaglandin E2, which remained undetectable for the duration of the study, showed up-regulation of expression after incubation in conditioned medium. 28SC incubated in melanoma conditioned medium expressed higher levels of interleukin-6 than did uveal melanoma cells incubated in monocyte conditioned medium. In addition each cell line exhibited a distinct pattern of expression with individual cell lines exhibiting peak levels of cytokine production at different time points. The results of this study offer insight into the mechanism by which interleukin 6 may be involved in tumor-host interactions potentially favoring tumor growth, survival, and proliferation.

Multiparametric flow cytometric analysis of inter-patient variation in STAT1 phosphorylation following interferon Alfa immunotherapy

BACKGROUND

Regulation of gene expression by signal transducer and activator of transcription 1 (STAT1) within host tissues mediates the antitumor effects of interferon alfa (IFN alpha). We used a novel flow cytometric assay to examine phosphorylation-mediated activation of STAT1 within immune effector cell subsets following in vitro or in vivo IFN alpha treatments.

METHODS

Peripheral blood mononuclear cells (PBMCs) isolated from healthy donors (n = 17) or melanoma patients (n = 19) were treated in vitro with interferon alfa-2b (IFN alpha-2b) or phosphate-buffered saline (PBS) and subjected to multiparametric flow cytometry to measure the levels of phosphorylated STAT1 (P-STAT1) within immune cell subsets. We similarly analyzed PBMCs isolated from melanoma patients before and 1 hour after immunotherapy with IFN alpha-2b. All statistical tests were two-sided.

RESULTS

P-STAT1 levels in all major immune cell subsets increased within 15 minutes of in vitro IFN alpha-2b treatment of PBMCs; the increase was most pronounced in T lymphocytes and monocytes. Relatively low doses of IFN alpha-2b (i.e., 10(2)-10(3) IU/mL) induced maximal STAT1 activation in vitro. Compared with melanoma patients, healthy donors had higher basal levels of P-STAT1 (specific fluorescence [Fsp]; i.e., Fsp(PBS), the level of P-STAT1 in PBS-treated cells) in total PBMCs, natural killer (NK) cells, and T cells (mean Fsp(PBS) in total PBMCs: 5.5 in healthy donors versus 1.6 in patients, difference = 3.9, 95% confidence interval [CI] = 1.4 to 6.5, P =.004; mean Fsp(PBS) in NK cells: 4.6 in healthy donors versus 0.9 in patients, difference = 3.7, 95% CI = 1.7 to 5.7, P =.001; mean Fsp(PBS) in T cells: 6.8 in healthy donors versus 0.9 in patients, difference = 5.9, 95% CI = 2.5 to 9.3, P =.002). P-STAT1 was detected in the NK and T cells of two patients who received IFN alpha-2b immunotherapy (20 MU/m2 [MU = million units], administered by intravenous injection). P-STAT1 levels in the PBMCs of a patient treated sequentially with 5 MU/m2 and 10 MU/m2 IFN alpha-2b (administered by subcutaneous injection) also increased in response to treatments with IFN alpha-2b but did not increase further with the increased dosage of IFN alpha-2b.

CONCLUSION

This flow cytometry method can be used to monitor STAT1 activation within subsets of immune cells from patients undergoing IFN alpha immunotherapy.

The antitumor effects of IFN-alpha are abrogated in a STAT1-deficient mouse

IFN-alpha activates the signal transducer and activator of transcription (STAT) family of proteins; however, it is unknown whether IFN-alpha exerts its antitumor actions primarily through a direct effect on malignant cells or by stimulating the immune system. To investigate the contribution of STAT1 signaling within the tumor, we generated a STAT1-deficient melanoma cell line, AGS-1. We reconstituted STAT1 into AGS-1 cells by retroviral gene transfer. The resulting cell line (AGS-1STAT1) showed normal regulation of IFN-alpha-stimulated genes (e.g., H2k, ISG-54) as compared with AGS-1 cells infected with the empty vector (AGS-1MSCV). However, mice challenged with the AGS-1, AGS-1STAT1, and AGS-1MSCV cell lines exhibited nearly identical survival in response to IFN-alpha treatment, indicating that restored STAT1 signaling within the tumor did not augment the antitumor activity of IFN-alpha. In contrast, STAT1-/- mice could not utilize exogenous IFN-alpha to inhibit the growth of STAT1+/+ melanoma cells in either an intraperitoneal tumor model or in the adjuvant setting. The survival of tumor-bearing STAT1-/- mice was identical regardless of treatment (IFN-alpha or PBS). Additional cell depletion studies demonstrated that NK cells mediated the antitumor effects of IFN-alpha. Thus, STAT1-mediated gene regulation within immune effectors was necessary for mediating the antitumor effects of IFN-alpha in this experimental system.