Melanoma-conditioned Medium Research Articles

Melanoma stimulates the proteolytic activity of HaCaT keratinocytes

BackgroundKeratinocytes constitute a major part of the melanoma microenvironment, considering their protective role towards melanocytes in physiological conditions. However, their interactions with tumor cells following melanomagenesis are still unclear.MethodsWe used two in vitro models (melanoma-conditioned media and indirect co-culture of keratinocytes with melanoma cells on Transwell inserts) to activate immortalized keratinocytes towards cancer-associated ones. Western Blotting and qPCR were used to evaluate keratinocyte markers and mediators of cell invasiveness on protein and mRNA expression level respectively. The levels and activity of proteases and cytokines were analysed using gelatin-FITC staining, gelatin zymography, chemiluminescent enzymatic test, as well as protein arrays. Finally, to further study the functional changes influenced by melanoma we assessed the rate of proliferation of keratinocytes and their invasive abilities by employing wound healing assay and the Transwell filter invasion method.ResultsHaCaT keratinocytes activated through incubation with melanoma-conditioned medium or indirect co-culture exhibit properties of less differentiated cells (downregulation of cytokeratin 10), which also prefer to form connections with cancer cells rather than adjacent keratinocytes (decreased level of E-cadherin). While they express only a small number of cytokines, the variety of secreted proteases is quite prominent especially considering that several of them were never reported as a part of secretome of activated keratinocytes’ (e.g., matrix metalloproteinase 3 (MMP3), ADAM metallopeptidase with thrombospondin type 1 motif 1). Activated keratinocytes also seem to exhibit a high level of proteolytic activity mediated by MMP9 and MMP14, reduced expression of TIMPs (tissue inhibitor of metalloproteinases), upregulation of ERK activity and increased levels of MMP expression regulators-RUNX2 and galectin 3. Moreover, cancer-associated keratinocytes show slightly elevated migratory and invasive abilities, however only following co-culture with melanoma cells on Transwell inserts.ConclusionsOur study offers a more in-depth view of keratinocytes residing in the melanoma niche, drawing attention to their unique secretome and mediators of invasive abilities, factors which could be used by cancer cells to support their invasion of surrounding tissues.52obFQmRyJn1nHi_mM3M7bVideo abstract

In Vitro Differentiation of Tumor-Associated Macrophages from Monocyte Precursors with Modified Melanoma-Conditioned Medium.

Tumor-associated macrophages (TAMs) are one of most important components of the tumor microenvironment. Although many assays have been developed to differentiate monocytes into macrophages (Mϕ) for studying the biology of TAMs in vitro, little is known whether the macrophages induced by these approaches can recapitulate the biology of TAMs present in the tumor microenvironment. We have developed a novel assay to differentiate human monocytes into TAMs using modified melanoma-conditioned medium, which is derived from the concentrated tumor cell culture medium. Characterization of these modified melanoma-conditioned medium-induced macrophages (MCMI-Mϕ) by multiple flow cytometry, Luminex, microarray, and immunohistochemistry analyses indicates that MCMI-Mϕ are phenotypically and functionally highly similar to the TAMs present in the tumor microenvironment.

Heterotypic signaling between dermal fibroblasts and melanoma cells induces phenotypic plasticity and proteome rearrangement in malignant cells

The signaling events triggered by soluble mediators released from both transformed and stromal cells shape the phenotype of tumoral cells and have significant implications in cancer development and progression. In this study we performed an in vitro heterotypic signaling assays by evaluating the proteome diversity of human dermal fibroblasts after stimulation with the conditioned media obtained from malignant melanoma cells. In addition, we also evaluated the changes in the proteome of melanoma cells after stimulation with their own conditioned media as well as with the conditioned medium from melanoma-stimulated fibroblasts. Our results revealed a clear rearrangement in the proteome of stromal and malignant cells upon crosstalk of soluble mediators. The main proteome signature of fibroblasts stimulated with melanoma conditioned medium was related to protein synthesis, which indicates that this process might be an early response of stromal cells. In addition, the conditioned medium derived from ‘primed’ stromal cells (melanoma-stimulated fibroblasts) was more effective in altering the functional phenotype (cell migration) of malignant cells than the conditioned medium from non-stimulated fibroblasts. Collectively, self- and cross-stimulation may play a key role in shaping the tumor microenvironment and enable tumoral cells to succeed in the process of melanoma progression and metastasis. Although the proteome landscape of cells participating in such a heterotypic signaling represents a snapshot of a highly dynamic state, understanding the diversity of proteins and enriched biological pathways resulting from stimulated cell states may allow for targeting specific cell regulatory motifs involved in melanoma progression and metastasis.

Immunomodulatory Protective Effects of Rb9 Cyclic-Peptide in a Metastatic Melanoma Setting and the Involvement of Dendritic Cells.

The cyclic VHCDR3-derived peptide (Rb9) from RebMab200 antibody, directed to a NaPi2B phosphate-transport protein, displayed anti-metastatic melanoma activity at 50–300 μg intraperitoneally injected in syngeneic mice. Immune deficient mice failed to respond to the peptide protective effect. Rb9 induced increased CD8+ T and low Foxp3+ T cell infiltration in lung metastases and high IFN-γ and low TGF-β in lymphoid organs. The peptide co-localized with F-actin and a nuclear site in dendritic cells and specifically bound to MIF and CD74 in a dot-blot setting. Murine bone-marrow dendritic cells preincubated with Rb9 for 6 h were treated with MIF for short time periods. The modulated responses showed stimulation of CD74 and inhibition of pPI3K, pERK, and pNF-κB as compared to MIF alone. Rb9 in a melanoma-conditioned medium, stimulated the M1 type conversion in bone marrow-macrophages. Functional aspects of Rb9 in vivo were studied in therapeutic and prophylactic protocols using a melanoma metastatic model. In both protocols Rb9 exhibited a marked anti-melanoma protection. Human dendritic cells were also investigated showing increased expression of surface markers in response to Rb9 incubation. Rb9 either stimulated or slightly inhibited moDCs submitted to inhibitory (TGF-β and IL-10) or activating (LPS) conditions, respectively. Lymphocyte proliferation was obtained with moDCs stimulated by Rb9 and tumor cell lysate. In moDCs from cancer patients Rb9 exerted immunomodulatory activities depending on their functional status. The peptide may inhibit over-stimulated cells, stimulate poorly activated and suppressed cells, or cause instead, little phenotypic and functional alterations. Recently, the interaction MIF-CD74 has been associated to PD-L1 expression and IFN-γ, suggesting a target for melanoma treatment. The effects described for Rb9 and the protection against metastatic melanoma may suggest the possibility of a peptide reagent that could be relevant when associated to modern immunotherapeutic procedures.

Melanoma-conditioned medium promotes cytotoxic immune responses by murine bone marrow-derived monocytes despite their expression of 'M2' markers.

Macrophages have been shown to infiltrate a wide range of malignancies and are often considered to promote tumour survival, growth and spread. However, the source and behaviour of discrete tumour-associated macrophage populations are still poorly understood. Here we show a novel method for the rational development of bone marrow-derived monocytes appropriate for the study of processes which involve the contribution of circulating inflammatory monocytes. We have shown that in response to tumour-conditioned medium, these cells upregulate CD206 and CD115, markers traditionally associated with M2-type macrophages. Treated cells show reduced capacity for cytokine secretion but significantly impact CD4+ and CD8+ T-cell proliferation and polarization. Coculture with conditioned bone marrow-derived monocytes significantly reduced CD4+ T-cell proliferation but increased CD8+ T-cell proliferation and granzyme B expression with significant induction of IFNγ secretion by both CD4+ and CD8+ T cells, indicating that these cells may have a role in promoting anti-cancer immunity.

Dual targeting of C-kit and Integrin Linked Kinase abrogates the phosphorylation of S6 ribosomal protein and reduces melanoma cell growth

Background: Activating mutations in c-kit have been observed in distinct subtypes of melanoma and are associated with disease progression and the development of resistance to treatment. Mutant c-kit uses mainly the phosphatidylinositol 3 kinase (PI3k)/Akt pathway and to a lesser extent the mitogen activated protein kinase (MAPK) pathway in order to promote characteristics of the cancer phenotype, such as excessive proliferation, angiogenesis and invasiveness. However, clinical studies on the inhibition of c-kit in melanoma patients have yielded disappointing results. The reactivation of these pathways have been reported in treatment resistant melanoma cells. Previously we showed that downregulation of integrin linked kinase (ILK), an intracellular adapter molecule that promotes tumor progression and angiogenesis when dysregulated, suppressed Akt phosphorylation and inhibited tumor growth. Therefore we investigated the effects of dual inhbition of c-kit and ILK on tumor cell growth and angiogenesis. Methods: The effects of dual blocking of c-kit and ILK-down regulation using siRNA on tumor cell growth were evaluated in an in vitro co-culture system that contained human vein endothelial cells (HUVECs) and melanoma cells. To investigate the effects of blocking c-kit and ILK on angiogenesis, the migration and invasion of HUVECs in response to conditioned medium from melanoma cells was studied using the xCELLigence system, while endothelial cell tube formation was studied using a collagen-based assay. Protein array studies were employed to investigate the expression patterns of angiogenic proteins in mono- and co-cultured cells. Further marker expression was determined using immunocytochemistry. Results: Significant inhibition of melanoma cell growth was observed in treated co-cultures, and the inhibition correlated with reduced expression of S6 ribosomal protein and S6 kinase. ILK-knockdown inhibited endothelial cell migration and invasion, as well as endothelial cell morphogenesis induced by melanoma conditioned medium. Results also revealed an increase in the expression of Platelet Factor 4 (PF4), and a suppression of proangiogenic factors, including leptin, vascular endothelial growth factor and basic fibroblast growth factor. Conclusions: Findings from this study suggest that the cross-talk between melanoma and endothelial cells which supports tumor cell growth, can be disrupted by dual targeting of c-kit and ILK. Furthermore, dual targeting of c-kit and ILK which also resulted in the altered expression profile of angiogenesis markers to favor antiangiogenesis, may imply that such dual targeting could contribute to enhancing complimentary approaches for melanoma therapy. Legal entity responsible for the study: Angiogenesis Laboratory, University of Pretoria Funding: National Research Foundation, University of Pretoria Disclosure: All authors have declared no conflicts of interest.

Bypassing STAT3-mediated inhibition of the transcriptional regulator ID2 improves the antitumor efficacy of dendritic cells.

Despite the potent ability of dendritic cells (DCs) to stimulate lymphocyte responses and host immunity, granulocyte-macrophage colony-stimulating factor-derived DCs (GM-DCs) used as antitumor vaccines have demonstrated relatively modest success in cancer immunotherapy. We found that injecting GM-DCs into melanoma tumors in mice, or culturing GM-DCs with melanoma-secreted cytokines or melanoma-conditioned medium, rapidly suppressed DC-intrinsic expression of the gene encoding inhibitor of differentiation 2 (ID2), a transcriptional regulator. Melanoma-associated cytokines repressed Id2 transcription in murine DCs through the activation of signal transducer and activator of transcription 3 (STAT3). Enforced expression of ID2 in GM-DCs (ID2-GM-DCs) suppressed their production of the proinflammatory cytokine tumor necrosis factor-α (TNF-α). Vaccination with ID2-GM-DCs slowed the progression of melanoma tumors and enhanced animal survival, which was associated with an increased abundance of tumor-infiltrating interferon-γ-positive CD4(+) effector and CD8(+) cytotoxic T cells and a decreased number of tumor-infiltrating regulatory CD4(+) T cells. The efficacy of the ID2-GM-DC vaccine was improved by combinatorial treatment with a blocking antibody to programmed cell death protein-1 (PD-1), a current immunotherapy that overcomes suppressive immune checkpoint signaling. Collectively, our data reveal a previously unrecognized STAT3-mediated immunosuppressive mechanism in DCs and indicate that DC-intrinsic ID2 promotes tumor immunity by modulating tumor-associated CD4(+) T cell responses. Thus, inhibiting STAT3 or overexpressing ID2 selectively in DCs may improve the efficiency of DC vaccines in cancer therapy.

Melanomas prevent endothelial cell death under restrictive culture conditions by signaling through AKT and p38 MAPK/ ERK-1/2 cascades

ABSTRACTAlthough melanoma progression and staging is clinically well characterized, a large variation is observed in pathogenesis, progression, and therapeutic responses. Clearly, intrinsic characteristics of melanoma cells contribute to this variety. An important factor, in both progression of the disease and response to therapy, is the tumor-associated vasculature. We postulate that melanoma cells communicate with endothelial cells (ECs) in order to establish a functional and supportive blood supply. We investigated the angiogenic potential of human melanoma cell lines by monitoring the survival of ECs upon exposure to melanoma conditioned medium (CM), under restrictive conditions. We observed long-term (up to 72 h) EC survival under hypoxic conditions upon treatment with all melanoma CMs. No such survival effect was observed with the CM of melanocytes. The CM of pancreatic and breast tumor cell lines did not show a long-term survival effect, suggesting that the survival factor is specific to melanoma cells. Furthermore, all size fractions (up to < 1 kDa) of the melanoma CM induced long-term survival of ECs. The survival effect observed by the < 1 kDa fraction excludes known pro-angiogenic factors. Heat inactivation and enzymatic digestion of the CM did not inactivate the survival factor. Global gene expression and pathway analysis suggest that this effect is mediated in part via the AKT and p38 MAPK/ ERK-1/2 signaling axis. Taken together, these data indicate the production of (a) survival factor/s (< 1 kDa) by melanoma cell lines, which enables long-term survival of ECs and promotes melanoma-induced angiogenesis.

Ilexgenin A induces B16-F10 melanoma cell G1/S arrest in vitro and reduces tumor growth in vivo.

The present study aimed to investigate the anti-tumor activity of Ilexgenin A in B16-F10 murine melanoma and to evaluate its effect on the production of tumor-associated inflammatory cytokines. In vitro, our study showed that Ilexgenin A inhibited the proliferation of B16-F10 murine melanoma cells in a dose- and time-dependent manner, and this effect could be ascribed to the arrest of the cell cycle at G0/G1. In vivo, we evaluated the anti-tumor activity of Ilexgenin A in a tumor-bearing mouse model. The results showed that Ilexgenin A reduced the tumor weight by 51.13% (p<0.01). The Ilexgenin A treatment groups showed no apparent side effects during the treatment period. In addition, a histological analysis revealed that Ilexgenin A changed the cell morphology, and induced large areas of necrosis that correlated with a reduction in tumor size. The detection of inflammatory cytokines indicated that the IL-6 level decreased (p<0.001) and the TNF-α level increased (p<0.01) in mice treated with Ilexgenin A. Ilexgenin A also inhibited the IL-6 production of macrophages stimulated by melanoma conditioned medium (MCM) significantly (p<0.001). Importantly, Ilexgenin A dramatically prolonged survival time (p<0.001). In conclusion, Ilexgenin A could be regarded as a promising agent for the treatment of melanoma; it exerts anti-melanoma activity by arresting the cell cycle at G0/G1 and regulating IL-6 and TNF-α production.

Antifibrogenic effects of B16 melanoma-conditioned medium

BackgroundSome malignant cancers show high levels of local invasiveness by the secretion of soluble factors that can degrade adjacent tissues and suppress surrounding cell growth. We investigated the possibility of treating fibroproliferative scars based on these properties of malignant melanoma. Material and methodsB16 melanoma-conditioned medium (B16 M-CM) was added to keloid fibroblasts (KFs), and proliferation, migration, and type I collagen production were measured. The cell cycle and signaling pathways were also analyzed. Proteins associated with cell proliferation were measured with Western blot analysis. Animal experiments using a rabbit ear model was performed to confirm the effect of B16 M-CM in vivo. ResultsB16 M-CM reduced proliferation, migration, and type I collagen production of KFs. This treatment also increased the number of cells in the subG1 phase and decreased phosphorylation levels of AKT, extracellular signal-regulated kinase1/2, cyclin D1, and c-Myc of KFs. Additionally, B16 M-CM reduced the thickness of rabbit ear scars in the rabbit ear model in vivo. ConclusionsB16 M-CM can suppress proliferation, migration, and type I collagen production of KFs. In addition, concentrated B16 M-CM reduced scar thickness in the rabbit ear model. The specific proteins involved should be identified in a future study.

LFA-1 and ICAM-1 expression induced during melanoma-endothelial cell co-culture favors the transendothelial migration of melanoma cell lines in vitro

BackgroundPatients with metastatic melanoma have a poor median rate of survival. It is therefore necessary to increase our knowledge about melanoma cell dissemination which includes extravasation, where cancer cells cross the endothelial barrier. Extravasation is well understood during travelling of white blood cells, and involves integrins such as LFA-1 (composed of two chains, CD11a and CD18) expressed by T cells, while ICAM-1 is induced during inflammation by endothelial cells. Although melanoma cell lines cross endothelial cell barriers, they do not express LFA-1. We therefore hypothesized that melanoma-endothelial cell co-culture might induce the LFA-1/ICAM ligand/receptor couple during melanoma transmigration.MethodsA transwell approach has been used as well as blocking antibodies against CD11a, CD18 and ICAM-1. Data were analyzed with an epifluorescence microscope. Fluorescence intensity was quantified with the ImageJ software.ResultsWe show here that HUVEC-conditioned medium induce cell-surface expression of LFA-1 on melanoma cell lines. Similarly melanoma-conditioned medium activates ICAM-1 expression in endothelial cells. Accordingly blocking antibodies of ICAM-1, CD11a or CD18 strongly decrease melanoma transmigration. We therefore demonstrate that melanoma cells can cross endothelial monolayers in vitro due to the induction of ICAM-1 and LFA-1 occurring during the co-culture of melanoma and endothelial cells. Our data further suggest a role of LFA-1 and ICAM-1 in the formation of melanoma cell clumps enhancing tumor cell transmigration.ConclusionMelanoma-endothelial cell co-culture induces LFA-1 and ICAM-1 expression, thereby favoring in vitro melanoma trans-migration.

Melanoma‐derived conditioned media efficiently induce the differentiation of monocytes to macrophages that display a highly invasive gene signature

The presence of tumor-associated macrophages (TAMs) in melanomas is correlated with a poor clinical prognosis. However, there is limited information on the characteristics and biological activities of human TAMs in melanomas. In this study, we developed an in vitro method to differentiate human monocytes to macrophages using modified melanoma-conditioned medium (MCM). We demonstrate that factors from MCM-induced macrophages (MCMI-Mφ) express both M1-Mφ and M2-Mφ markers and inhibit melanoma-specific T-cell proliferation. Furthermore, microarray analyses reveal that the majority of genes up-regulated in MCMI-Mφ are associated with tumor invasion. The most strikingly up-regulated genes are CCL2 and MMP-9. Consistent with this, blockade of both CCL-2 and MMPs diminish MCMI-Mφ-induced melanoma invasion. Finally, we demonstrated that both MCMI-Mφ and in vivo TAMs express the pro-invasive, melanoma-associated gene, glycoprotein non-metastatic melanoma protein B. Our study provides a framework for understanding the mechanisms of cross-talk between TAMs and melanoma cells within the tumor microenvironment.

Induction of metallothionein expression during monocyte to melanoma-associated macrophage differentiation

Tumor-associated macrophages (TAMs) play a critical role in melanoma growth and metastasis. Infiltration of TAMs correlates with the poor prognosis of melanoma. TAMs are differentiated from monocytes in response to the tumor microenvironment cue. However, the mechanism how TAMs adapt to the tumor microenvironment after differentiation from monocytes is not fully understood. In addition, specific identification of TAMs in melanoma is difficult because the expression of the most commonly used macrophage marker, CD68, is also expressed in melanoma cells. In an earlier study, we found by gene microarray analysis that seven members of the metallothionein (MTs) family were upregulated in melanoma-conditioned medium induced macrophages (MCIM-Mϕ). MTs have been implicated in zinc metabolism and inflammation. In the present study, we confirmed that expression of metallothionein is induced in M-CSF differentiated macrophages (M-CSF/Mϕ) and MCIM-Mϕ at both the mRNA and protein levels using real-time PCR, immunofluorescence, and western blot analysis. Furthermore, we demonstrated the presence of metallothionein in melanoma tissues in vivo and that metallothionein was co-localized with TAMs markers, CD68 and CD163. Finally, we demonstrated the induction of the zinc importer gene Zip8 both in M-CSF/Mϕ and MCIM-Mϕ. Our study identifies metallothionein as a novel marker for TAMs and suggests that metallothionein might play important roles in macrophage adaptation and function in the tumor microenvironment.

Abstract 3464: Melanomas differentially regulate directionally persistent endothelial cell migration

Abstract Introduction: Cutaneous melanoma is the most aggressive form of skin cancer. Although early detection and surgical resection of the primary lesion could improve survival, metastatic melanoma is by large refractory to therapy and predicts poor prognosis. Melanoma progression and metastatic dissemination relies on the process of angiogenesis. The angiogenic process is comprised of a stringent cascade of events ultimately resulting in a new vessel. Pathological (tumor) angiogenesis, however, is mediated by an array of angiogenic modulators produced by the tumor itself. Such tumor-associated modulators arbitrate the enhanced and awry proliferative, survival and migratory responses exhibited by endothelial cells, culminating in unregulated and unimpeded angiogenesis. Project Description: In the current study, we evaluated the angiogenic potential of human melanoma cell lines, based on their ability to regulate directionally persistent endothelial cell (EC) migration. Melanoma conditioned medium (CM) from three human melanoma cell lines (BLM, Mel57, 1F6), differing in their degree of aggressiveness and clinical staging, were used to assess the migratory responses of ECs in a 2-D migration assay, previously established by our group. This assay involves the use of the ‘ring and barrier’ system, wherein the ECs were cultured in a migration ring to generate a confluent area at the periphery and a cell free area in the center. EC migration in response to the tested CMs was monitored real-time, and various migration parameters were determined. Additionally, CM size fractions were tested to delineate the differences observed in migratory responses of the ECs to the tested CMs. Results and Conclusions: There was a clear correlation between EC migration and the degree of aggressiveness of the melanoma cell line used to generate the CM. While the CM of the highly aggressive BLM tumor cells induced a high migratory response in ECs, the CM of the less aggressive 1F6 cells had an inhibitory effect. The 1F6 CM was further size fractionated and it was observed that the factor/s responsible for this inhibition lay in the 10-30 kD range. Gene and protein expression verification helped identify a varied protein expression profile, which are secreted into the CM. Their expression inversely correlated with aggressiveness of the melanoma cell line and ability of the respective CMs to affect EC migration. CM of 1F6 cells silenced with shRNA induced EC migration, while both recombinant protein as well as the CM of BLM cells transfected with protein expressing plasmid mitigated EC migration. Taken together, these results demonstrate that the soluble protein in the CM inhibits the inherent propensity of endothelial cells to undergo directionally persistent migration and that this expression could impede EC melanoma-induced angiogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3464. doi:10.1158/1538-7445.AM2011-3464

Zeaxanthin inhibits PDGF‐BB‐induced migration in human dermal fibroblasts

Zeaxanthin is the dihydroxy carotenoid and is distributed in our daily foods. Various natural carotenoids, including zeaxanthin, have been shown to inhibit proliferation of several types of cancer cells, but available data on the effect of zeaxanthin on skin fibroblasts and melanoma cells are limited. Platelet-derived growth factor (PDGF) functions as a chemotactic factor for dermal fibroblasts and plays an important role in the progression of melanoma. In this study, we investigated the effects of zeaxanthin on the migration of skin fibroblasts induced by PDGF-BB and melanoma cells. We demonstrated that zeaxanthin inhibited PDGF-BB-induced skin fibroblast migration on collagen and gelatin by a modified Boyden chamber system. The electric cell-substrate impedance sensing (ECIS) method also showed similar inhibitory effects of zeaxanthin on the migration of fibroblasts. In functional studies, zeaxanthin decreased melanoma-induced fibroblast migration in a non-contact coculture system and also the migration stimulated by melanoma-derived conditioned medium. Further analysis showed that zeaxanthin attenuated PDGF-BB and melanoma-conditioned medium induced phosphorylation of PDGFR-beta and MAP kinase in a concentration-dependent manner in human skin fibroblasts. However, these effects did not result from direct interaction of zeaxanthin with PDGF-BB. Thus, our results provide the first evidence showing that zeaxanthin is an effective inhibitor of migration of stromal fibroblasts induced by PDGF-BB and melanoma cells and this effect may further support its antitumor potential.

The effects of a cyclooxygenase-2 (COX-2) expression and inhibition on human uveal melanoma cell proliferation and macrophage nitric oxide production

BackgroundCyclooxygenase-2 (COX-2) expression has previously been identified in uveal melanoma although the biological role of COX-2 in this intraocular malignancy has not been elucidated. This study aimed to investigate the effect of a COX-2 inhibitor on the proliferation rate of human uveal melanoma cells, as well as its effect on the cytotoxic response of macrophages.MethodsHuman uveal melanoma cell lines were transfected to constitutively express COX-2 and the proliferative rate of these cells using two different methods, with and without the addition of Amfenac, was measured. Nitric oxide production by macrophages was measured after exposure to melanoma-conditioned medium from both groups of cells as well as with and without Amfenac, the active metabolite of Nepafenac.ResultsCells transfected to express COX-2 had a higher proliferation rate than those that did not. The addition of Amfenac significantly decreased the proliferation rate of all cell lines. Nitric oxide production by macrophages was inhibited by the addition of melanoma conditioned medium, the addition of Amfenac partially overcame this inhibition.ConclusionAmfenac affected both COX-2 transfected and non-transfected uveal melanoma cells in terms of their proliferation rates as well as their suppressive effects on macrophage cytotoxic activity.

Determination of anti-angiogenic therapeutic targets by gene array analysis of differentially expressed angiogenic factors by malignant melanoma

241 The population of patients with malignant melanoma is one of the most rapidly increasing cancer groups worldwide. Because current therapeutic methods for metastatic melanoma are poorly efficacious, enhanced understanding of melanoma development is required. Previous research has shown a possible correlation between the degree of vascularization of melanoma and their metastasizing capacity. Inhibition of angiogenesis, the development of new blood vessels out of pre-existing ones, could therefore be a potential therapy. Tumor cells initiate the onset of new blood vessel formation by releasing VEGF and numerous other angiogenic factors. In this study we focused on melanoma-mediated endothelial cell survival. Six human melanoma cell lines, which differ in degree of aggressiveness, were cultured under normoxic (20%O 2 ) and hypoxic (1%O 2 ) conditions, since hypoxia strongly induces angiogenic factor production. Melanoma-conditioned medium of all cell lines was capable of augmenting endothelial cell survival after hypoxia. The activity of VEGF and the determination of differentially expressed pro- and anti-angiogenic factors by the selected melanoma cells was determined by means of RT-PCR, ELISA and Affymetrix-based microarray analyses. Clearly, the melanoma-induced endothelial cell survival was not solely dependent on VEGF. Our observations suggest that, instead of focusing on a single factor, efficient anti-angiogenic treatment of melanoma may require identification and blocking of several factors.

Lymphatic endothelium-specific hyaluronan receptor LYVE-1 is expressed by stabilin-1+, F4/80+, CD11b+ macrophages in malignant tumours and wound healing tissuein vivo and in bone marrow culturesin vitro: implications for the assessment of lymphangiogenesis

Lymphangiogenesis is a novel prognostic parameter for several cancers that is preferentially quantified by immunohistochemistry of the lymphatic endothelium-specific hyaluronan receptor LYVE-1. Recently, the specificity of LYVE-1 was challenged by serendipitous observations of LYVE-1 expression in rare tissue macrophages. As expression of the hyaluronan receptor-like molecule stabilin-1 is shared by sinusoidal endothelium and macrophages, a thorough analysis of LYVE-1 expression was performed using macrophage-specific markers in vivo and in vitro. In murine tumour models and excisional wound healing, LYVE-1 expression occurred in a subset of CD11b(+), F4/80(+) tissue macrophages that preferentially co-expressed stabilin-1. Upon comparison of single- and double-labelling immunofluorescence, it became apparent that LYVE-1(+) macrophages mimic sprouting and collapsed lymphatic vessels. In vitro, LYVE-1 expression was induced in 25-40% of murine bone marrow-derived macrophages upon exposure to B16F1 melanoma-conditioned medium and IL-4/dexamethasone. By FACS analysis, 11.5% of bone marrow-derived macrophages were LYVE-1(+), stabilin-1(+) double-positive, while 9.9% were LYVE-1(+), stabilin-1(-) and 33.5% were LYVE-1(-), stabilin-1(+). Northern and western analyses confirmed expression of LYVE-1 mRNA and protein in bone marrow-derived macrophages. In the light of the current debate about true endothelial trans-differentiation versus endothelial mimicry of monocytes/macrophages, LYVE-1(+), stabilin-1(+) non-continuous endothelial-like macrophages will require further developmental and functional analyses. In conclusion, the findings imply that LYVE-1 staining must be supplemented by double labelling with macrophage markers in order to differentiate clearly between LYVE-1(+) lymphatics and LYVE-1(+) tumour-infiltrating macrophages. This improved approach will help to clarify the prognostic significance of lymphangiogenesis in malignant tumours.

Melanoma skews dendritic cells to facilitate a T helper 2 profile

Patients with progressing melanoma have a circulating cytokine profile reflecting a T helper cell type 2 (Th2) imbalance, while patients responding to therapy favor a Th1 profile. The aim of this study was to determine the role of circulating dendritic cells (DCs) in mediating this imbalance. Isolated human peripheral blood mononuclear cells (PBMCs) were exposed to cell-free melanoma-conditioned medium (MCM) or control fibroblast-conditioned medium before stimulation. In separate experiments, isolated circulating DCs were exposed to MCM before addition of T cells. DC maturation and function were determined. Mixed leukocyte response T-cell proliferation was quantified and supernatants were assayed for Th1 (interleukin [IL]-2 and interferon gamma) and Th2 (IL-4, IL-5, and IL-10) cytokines. PBMCs exposed to MCM produced significantly more Th2-type cytokines (IL-4, IL-5, and IL-10) over time than those exposed to control medium. DCs exposed to MCM before addition of T cells, produced a similar pattern of a sustained longer term Th2 response after an initial burst of IL-2. Exposure to MCM did not significantly affect DC maturation or IL-12 production. T-cell proliferation did not change significantly in the mixed leukocyte response, however, the percentage of viable CD4+ T cells in the MCM-treated group was significantly less than control (37 vs 50%, P < .05). Exposure of PBMCs to melanoma produces a Th2-type cytokine profile, which may be, in part, facilitated by DCs.

Suppressive effect of Zedoariae rhizoma on pulmonary metastasis of B16 melanoma cells

The inhibitory effect of Curcuma zedoaria Roscoe (WE-CZ) on experimental pulmonary metastasis of B16 melanoma cells was investigated. The intake of WE-CZ at doses of 250 and 500 mg/kg for 6 weeks from 2 weeks before tumor inoculation significantly reduced the number of metastatic surface nodules in the lung, resulting in an extended life span. When the duration of WE-CZ intake was examined, survival time was not affected by pre-intake before B16 melanoma cell inoculation and was slightly extended by post-intake after B16 melanoma cell inoculation, although the life span was prolonged by intake throughout the experiment. To address the mechanism underlying the anti-metastatic effect of WE-CZ, we examined the issue of whether WE-CZ modulated macrophage function, which is involved in killing tumor cells. The intake of WE-CZ for 6 weeks increased nitric oxide (NO) production by macrophages following stimulation with lipopolysaccharide in a dose-dependent manner. The elevated NO was found to serve as a cytotoxic mediator against B16 melanoma cells in co-culture with macrophages. On the contrary, B16 melanoma-conditioned medium reduced NO production by macrophages. However, WE-CZ treatment significantly reversed the reduction in NO production by the conditioned medium. These findings indicate that WE-CZ possesses anti-migratory effects on B16 melanoma cells and that the macrophage function-modulating activity by WE-CZ appears to underlie its anti-metastatic activity, which leads to a decrease in the number of lung metastatic surface nodules and the extension of life span. These results suggest that WE-CZ may play important roles in the inhibition of cancer metastasis.