Effects of interferon alfa and gamma on human uveal melanoma cells in vitro

An update on inflammation in uveal melanoma

Uveal melanoma (UM) is the primary ocular cancer with upto 50% of patients dying from metastasis. Although rare, it is deadly as patients with metastatic UM seldom survive beyond 18 months after diagnosis. Chemotherapeutics have no proven efficacy, including immunotherapies that have been tried as current treatment options but produce marginal improvement in overall survival for UM patients. While therapeutics are low in efficacy, there is an urgent need to explore novel targets in the treatment of UM. This review provides an update on the contribution of inflammation to UM with a focus on exploring potential therapeutic targets related to the inflammatory tumour microenvironment. As a tumour promoting event, inflammation is one of the hallmarks of cancers. The presence of the inflammatory phenotype characterised by the abundance of immune mediators and proinflammatory cytokines surrounding UM tumours, is a potential area to explore novel therapeutic targets. Despite decades of investigation regarding the role UM tumour microenvironment has played, that of inflammation in UM progression remains poorly understood. With advancement of technologies, an understanding of the prognosis of UM has been accelerated. Excitingly, novel therapeutic targets related to the inflammatory tumour microenvironment have been identified and relevant studies are underway in their preliminary phases, illustrating optimistic results.

A Novel Four Genes of Prognostic Signature for Uveal Melanoma

Autophagy and immunity play critical roles in various cancers, but the prognostic impact of autophagy and immunity for uveal melanoma (UM) remains lacking. Therefore, the RNA sequencing of data in the TCGA-UVM dataset was downloaded from UCSC Xena database. The prognostic autophagy- and immunity-related genes (AIRGs) were selected via univariate Cox regression. Next, we applied LASSO method to construct four genes of signature in the TCGA-UVM and verified in another two GEO datasets (GSE84976 and GSE22138). This signature intimately associated with overall survival (OS) time and metastasis-free survival (MFS) time of UM, which could be considered as a prognostic indicator. Besides, by applying risk assessment, the patients of UM can be divided into two subgroups (high/low risk) with different survival time, distinct clinical outcomes, and immune microenvironments. Gene set enrichment analysis (GSEA) manifested that cancer hallmark epithelial-mesenchymal transition and KRAS pathways were positively activated in the high-risk group. Moreover, the high-risk group could be more sensitive to chemotherapies than the low-risk group. Thus, our finding suggested that the four genes of signature closely linked with UM risk and survival can afford more accurate survival prediction and potential therapeutic targets for clinical application.

LAG3 and Its Ligands Show Increased Expression in High-Risk Uveal Melanoma

Uveal melanoma (UM) is a rare ocular malignancy which originates in the uveal tract, and often gives rise to metastases. Potential targets for immune checkpoint inhibition are lymphocyte-activation gene 3 (LAG3) and its ligands. We set out to analyse the distribution of these molecules in UM. The expression of mRNA was determined using an Illumina array in 64 primary UM from Leiden. The T lymphocyte fraction was determined by digital droplet PCR. In a second cohort of 15 cases from Leiden, mRNA expression was studied by Fluidigm qPCR, while a third cohort consisted of 80 UM from TCGA. In the first Leiden cohort, LAG3 expression was associated with the presence of epithelioid cells (p = 0.002), monosomy of chromosome 3 (p = 0.004), and loss of BAP1 staining (p = 0.001). In this Leiden cohort as well as in the TCGA cohort, LAG3 expression correlated positively with the expression of its ligands: LSECtin, Galectin-3, and the HLA class II molecules HLA-DR, HLA-DQ, and HLA-DP (all p < 0.001). Furthermore, ligands Galectin-3 and HLA class II were increased in monosomy 3 tumours and the expression of LAG3 correlated with the presence of an inflammatory phenotype (T cell fraction, macrophages, HLA-A and HLA-B expression: all p < 0.001). High expression levels of LAG3 (p = 0.01), Galectin-3 (p = 0.001), HLA-DRA1 (p = 0.002), HLA-DQA1 (p = 0.04), HLA-DQB2 (p = 0.03), and HLA-DPA1 (p = 0.007) were associated with bad survival. We conclude that expression of the LAG ligands Galectin-3 and HLA class II strongly correlates with LAG3 expression and all are increased in UM with Monosomy 3/BAP1 loss. The distribution suggests a potential benefit of monoclonal antibodies against LAG3 or Galectin-3 as adjuvant treatment in patients with high-risk UM.

Identification of survival-related genes and a novel gene-based prognostic signature involving the tumor microenvironment of uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignant tumor in adults and almost fifty percent of patients subsequently develop systemic metastases usually involving the liver. The tumor microenvironment (TME) is crucial to the initiation and progression of tumors. In the present study, we comprehensively evaluated the TME of primary UM samples from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database by using several bioinformatic algorithms. The prognostic value of immune score and infiltrating immune cells in the TME were evaluated. Differentially expressed genes between the low- and high-immune score groups were also identified. The majority of tumor-infiltrating lymphocytes in UM have been determined to be activated CD8 + T cells. Therefore, weighted gene co-expression network analysis (WGCNA) was performed to identify the co-expression modules and genes significantly associated with the level of infiltrating CD8 + T cells in UM. Survival-related genes involved in the TME were identified by univariate Cox regression analysis. Furthermore, an eight-gene-based prognostic signature was established in the training dataset TCGA-UM via Lasso-penalized and multivariate Cox regression analyses. The predictive value of this signature was validated in two testing datasets. Besides, a nomogram was established to serve clinical practice. Moreover, hub genes involved in the infiltrating CD8 + T cells were identified and a potential targeted therapy for preventing metastasis of UM was proposed based on the results. In summary, our results provided a robust gene-based prognostic signature for predicting prognosis of UM patients and proposed a potential targeted therapy for preventing UM metastasis.

Translation of single-cell transcriptomic analysis of uveal melanomas to clinical oncology

Uveal melanoma (UM) is an aggressive and deadly neoplasm. In recent decades, great efforts have been made to obtain a more comprehensive understanding of genetics, genomics and molecular changes in UM, enabling the identification of key cellular processes and signalling pathways. Still, there is no effective treatment for the metastatic disease. Intratumoural heterogeneity (ITH) is thought to be one of the leading determinants of metastasis, therapeutic resistance and recurrence. Crucially, tumours are complex ecosystems, where cancer cells, and diverse cell types from their microenvironment engage in dynamic spatiotemporal crosstalk that allows cancer progression, adaptation and evolution. This highlights the urgent need to gain insight into ITH in UM and its intersection with the microenvironment to overcome treatment failure. Here we provide an overview of the studies and technologies to study ITH in human UMs and tumour micro-environmental composition. We discuss how to incorporate ITH into clinical consideration for the purpose of advocating for new clinical management. We focus on the application of single-cell transcriptomic analysis and propose that understanding the driving forces and functional consequences of the observed tumour heterogeneity holds promise for changing the treatment paradigm of metastatic UMs, surmounting resistance and improving patient prognosis.

Uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. UMs are usually initiated by a mutation in GNAQ or GNA11, unlike cutaneous melanomas, which usually harbour a BRAF or NRAS mutation. The annual incidence in Europe and the USA is ~6 per million population per year. Risk factors include fair skin, light-coloured eyes, congenital ocular melanocytosis, ocular melanocytoma and the BAP1-tumour predisposition syndrome. Ocular treatment aims at preserving the eye and useful vision and, if possible, preventing metastases. Enucleation has largely been superseded by various forms of radiotherapy, phototherapy and local tumour resection, often administered in combination. Ocular outcomes are best with small tumours not extending close to the optic disc and/or fovea. Almost 50% of patients develop metastatic disease, which usually involves the liver, and is usually fatal within 1 year. Although UM metastases are less responsive than cutaneous melanoma to chemotherapy or immune checkpoint inhibitors, encouraging results have been reported with partial hepatectomy for solitary metastases, with percutaneous hepatic perfusion with melphalan or with tebentafusp. Better insight into tumour immunology and metabolism may lead to new treatments.

HLA Expression in Uveal Melanoma: An Indicator of Malignancy and a Modifiable Immunological Target

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults, and gives rise to metastases in 50% of cases. The presence of an inflammatory phenotype is a well-known risk factor for the development of metastases. This inflammatory phenotype is characterized by the presence of high numbers of lymphocytes and macrophages, and a high expression of the HLA Class I and II antigens. An abnormal expression of HLA Class I may influence cytotoxic T lymphocyte (CTL) as well as Natural Killer (NK) cell responses. We provide a comprehensive review regarding the inflammatory phenotype in UM and the expression of locus- and allele-specific HLA Class I and of Class II antigens in primary UM and its metastases. Furthermore, we describe the known regulators and the role of genetics (especially chromosome 3 and BRCA-Associated Protein 1 (BAP1 status)), and, last but not least, the effect of putative therapeutic treatments on HLA expression.

Interferon Signaling Is Frequently Downregulated in Melanoma

Immune checkpoint inhibitors that block the programmed cell death protein 1/PD-L1 pathway have significantly improved the survival of patients with advanced melanoma. Immunotherapies are only effective in 15–40% of melanoma patients and resistance is associated with defects in antigen presentation and interferon signaling pathways. In this study, we examined interferon-γ (IFNγ) responses in a large panel of immune checkpoint inhibitor-naïve melanoma cells with defined genetic drivers; BRAF-mutant (n = 11), NRAS-mutant (n = 10), BRAF/NRAS wild type (n = 10), and GNAQ/GNA11-mutant uveal melanomas (UVMs) (n = 8). Cell surface expression of established IFNγ downstream targets PD-L1, PD-L2, HLA-A, -B, and -C, HLA-DR, and nerve growth factor receptor (NGFR) were analyzed by flow cytometry. Basal cellular expression levels of HLA-A, -B, -C, HLA-DR, NGFR, and PD-L2 predicted the levels of IFNγ-stimulation, whereas PD-L1 induction was independent of basal expression levels. Only 13/39 (33%) of the melanoma cell lines tested responded to IFNγ with potent induction of all targets, indicating that downregulation of IFNγ signaling is common in melanoma. In addition, we identified two well-recognized mechanisms of immunotherapy resistance, the loss of β-2-microglobulin and interferon gamma receptor 1 expression. We also examined the influence of melanoma driver oncogenes on IFNγ signaling and our data suggest that UVM have diminished capacity to respond to IFNγ, with lower induced expression of several targets, consistent with the disappointing response of UVM to immunotherapies. Our results demonstrate that melanoma responses to IFNγ are heterogeneous, frequently downregulated in immune checkpoint inhibitor-naïve melanoma and potentially predictive of response to immunotherapy.

Upregulation of HLA Expression in Primary Uveal Melanoma by Infiltrating Leukocytes

Introduction

Uveal melanoma (UM) with an inflammatory phenotype, characterized by infiltrating leukocytes and increased human leukocyte antigen (HLA) expression, carry an increased risk of death due to metastases. These tumors should be ideal for T-cell based therapies, yet it is not clear why prognostically-infaust tumors have a high HLA expression. We set out to determine whether the level of HLA molecules in UM is associated with other genetic factors, HLA transcriptional regulators, or microenvironmental factors.

Methods

28 enucleated UM were used to study HLA class I and II expression, and several regulators of HLA by immunohistochemistry, PCR microarray, qPCR and chromosome SNP-array. Fresh tumor samples of eight primary UM and four metastases were compared to their corresponding xenograft in SCID mice, using a PCR microarray and SNP array.

Results

Increased expression levels of HLA class I and II showed no dosage effect of chromosome 6p, but, as expected, were associated with monosomy of chromosome 3. Increased HLA class I and II protein levels were positively associated with their gene expression and with raised levels of the peptide-loading gene TAP1, and HLA transcriptional regulators IRF1, IRF8, CIITA, and NLRC5, revealing a higher transcriptional activity in prognostically-bad tumors. Implantation of fresh human tumor samples into SCID mice led to a loss of infiltrating leukocytes, and to a decreased expression of HLA class I and II genes, and their regulators.

Conclusion

Our data provides evidence for a proper functioning HLA regulatory system in UM, offering a target for T-cell based therapies.

Calcium regulation by temperature-sensitive transient receptor potential channels in human uveal melanoma cells

Uveal melanoma (UM) is both the most common and fatal intraocular cancer among adults worldwide. As with all types of neoplasia, changes in Ca(2+) channel regulation can contribute to the onset and progression of this pathological condition. Transient receptor potential channels (TRPs) and cannabinoid receptor type 1 (CB1) are two different types of Ca(2+) permeation pathways that can be dysregulated during neoplasia. We determined in malignant human UM and healthy uvea and four different UM cell lines whether there is gene and functional expression of TRP subtypes and CB1 since they could serve as drug targets to either prevent or inhibit initiation and progression of UM. RT-PCR, Ca(2+) transients, immunohistochemistry and planar patch-clamp analysis probed for their gene expression and functional activity, respectively. In UM cells, TRPV1 and TRPM8 gene expression was identified. Capsaicin (CAP), menthol or icilin induced Ca(2+) transients as well as changes in ion current behavior characteristic of TRPV1 and TRPM8 expression. Such effects were blocked with either La(3+), capsazepine (CPZ) or BCTC. TRPA1 and CB1 are highly expressed in human uvea, but TRPA1 is not expressed in all UM cell lines. In UM cells, the CB1 agonist, WIN 55,212-2, induced Ca(2+) transients, which were suppressed by La(3+) and CPZ whereas CAP-induced Ca(2+) transients could also be suppressed by CB1 activation. Identification of functional TRPV1, TRPM8, TRPA1 and CB1 expression in these tissues may provide novel drug targets for treatment of this aggressive neoplastic disease.

Influence of CD8+ T regulatory cells on intraocular tumor development

The interior of the eye, or uvea, is a site of immune privilege where certain immune responses are attenuated or completely excluded to protect non-regenerating tissues essential for vision. One consequence of this immunoregulation is compromised immune mediated elimination of intraocular tumors. For example, certain murine tumor cell lines which are rejected by host immune responses when transplanted in the skin grow progressively when placed in the anterior chamber (a.c.) of the eye. Progressive ocular tumor growth occurs despite induction of tumor-specific CD8+ T cell responses capable of eliminating a subsequent tumor challenge in the skin or opposite eye. Why these CD8+ T effectors fail to eliminate established ocular tumors is not known. It is well appreciated that growth of tumors in the a.c. induces the generation of immunosuppressive CD8+ T regulatory (Treg) cells. However, the contribution of CD8+ Treg in ocular tumor progression remains unclear. Several studies indicate that these CD8+ Treg target responding CD4+ T cells to inhibit their induction of macrophage-dependent delayed type hypersensitivity (DTH) responses to tumor antigens (Ags). However, induction of tumor-specific CD4+ T cell responses does not assure intraocular tumor elimination. This review is focused on how CD8+ Treg could influence the tumoricidal activity of ocular tumor-specific CD8+ T effector cells.

Costimulatory molecule expression on human uveal melanoma cells: functional analysis of CD40 and B7-H1

Costimulatory molecules play important roles in regulating T cell function in tumor immunity. In this study, we investigated costimulatory molecule expression on human uveal melanoma cells (a primary culture, and OCM-1, OMM-1 and 92-1 cell lines) and assessed the functional roles of selected costimulatory molecules. Uveal melanoma cells were incubated in the presence or absence of IFN-γ and expression of costimulatory molecules on the cells was measured by flow cytometry. The costimulatory effect of B7-H1-expressing uveal melanoma cells on cytokine production by purified T cells was studied in uveal melanoma/T cell co-culture experiments using a blocking anti-B7-H1 monoclonal antibody (mAb). The functional role of CD40-mediated interactions in modifying immune responses to uveal melanoma cells was assessed in vitro using recombinant human CD40 ligand (rhCD40L). MHC class I and B7-H1 were consistently detected and further upregulated by IFN-γ stimulation in all human uveal melanoma cell cultures. CD40 was consistently detected and further upregulated by IFN-γ stimulation in primary culture, OCM-1, and OMM-1 but not 92-1. IL-2 production from purified CD3(+) T cells co-stimulated with IFN-γ-treated uveal melanoma cells was significantly enhanced by the addition of anti-B7-H1 mAb. Treatment of primary culture, OCM-1, or OMM-1 with rhCD40L induced or enhanced secretion of chemokines IL-8, MCP-1, IP-10 and RANTES. These results suggest that the expression of B7-H1 on IFN-γ-treated uveal melanoma cells contributes to suppression of T cells by decreasing IL-2 production. In contrast, CD40 expressed on uveal melanoma cells plays an important role in augmenting anti-tumor immunity by stimulating chemokine production. The dual effects of CD40 and B7-H1 may contribute to positive or negative regulation of anti-tumor immune responses to human uveal melanoma.

Decitabine up-regulates S100A2 expression and synergizes with IFN-gamma to kill uveal melanoma cells

PURPOSE

Metastatic uveal melanoma is resistant to conventional chemotherapy and immunotherapy. In this study, we investigated the responsiveness of uveal melanoma cell lines to IFNs and the hypomethylating agent decitabine.

EXPERIMENTAL DESIGN

The uveal melanoma cell lines 92-1, UW-1, OCM-1, and MKT-BR were exposed to varying concentrations of IFN-alpha, IFN-gamma, and decitabine, alone and in combination. The effects of decitabine on gene expression were examined using DNA microarray analysis.

RESULTS

We found that IFN-gamma and decitabine induced cell death in uveal melanoma. Whereas a high concentration of IFN-gamma (1,000 units/mL) was required to induce cell death, we observed a dose-related increase in cell death when decitabine was used at a range of 0.1 to 10 micromol/L. Strikingly, 1 micromol/L decitabine synergized with 10 to 1,000 units/mL IFN-gamma to induce massive cell death. In contrast, decitabine had no effect on three cutaneous melanoma cell lines and exhibited no synergy with either IFN. In uveal melanoma, decitabine up-regulated the expression of genes involved in growth control and apoptosis and down-regulated genes that have been implicated in the malignant phenotype of cutaneous melanoma. The gene up-regulated to the greatest degree by decitabine and whose expression showed a dose-effect across the three concentrations of decitabine was S100A2, a putative tumor suppressor. The genes modulated by decitabine in uveal melanoma were largely unaffected in cutaneous melanoma.

CONCLUSIONS

These findings form a basis for testing the decitabine/IFN-gamma combination in metastatic uveal melanoma and for exploring the role of S100A2 in the susceptibility of uveal melanoma to IFN-mediated cell death.

Field production and functional evaluation of chloroplast-derived interferon-alpha2b

Type I interferons (IFNs) inhibit viral replication and cell growth and enhance the immune response, and therefore have many clinical applications. IFN-alpha2b ranks third in world market use for a biopharmaceutical, behind only insulin and erythropoietin. The average annual cost of IFN-alpha2b for the treatment of hepatitis C infection is $26,000, and is therefore unavailable to the majority of patients in developing countries. Therefore, we expressed IFN-alpha2b in tobacco chloroplasts, and transgenic lines were grown in the field after obtaining United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS) approval. Stable, site-specific integration of transgenes into chloroplast genomes and homoplasmy through several generations were confirmed. IFN-alpha2b levels reached up to 20% of total soluble protein, or 3 mg per gram of leaf (fresh weight). Transgenic IFN-alpha2b had similar in vitro biological activity to commercially produced PEG-Introntrade mark when tested for its ability to protect cells against cytopathic viral replication in the vesicular stomatitis virus cytopathic effect (VSV CPE) assay and to inhibit early-stage human immunodeficiency virus (HIV) infection. The antitumour and immunomodulating properties of IFN-alpha2b were also seen in vivo. Chloroplast-derived IFN-alpha2b increased the expression of major histocompatibility complex class I (MHC I) on splenocytes and the total number of natural killer (NK) cells. Finally, IFN-alpha2b purified from chloroplast transgenic lines (cpIFN-alpha2b) protected mice from a highly metastatic tumour line. This demonstration of high levels of expression of IFN-alpha2b, transgene containment and biological activity akin to that of commercial preparations of IFN-alpha2b facilitated the first field production of a plant-derived human blood protein, a critical step towards human clinical trials and commercialization.

Combined immunologic and anti-angiogenic therapy reduces hepatic micrometastases in a murine ocular melanoma model

PURPOSE

To evaluate the combined effect of neoadjuvant intracameral interferon alpha -2b and adjuvant low-dose angiostatin in reducing the number of hepatic micrometastases in a murine model of ocular melanoma.

METHODS

The posterior compartments of the right eyes of C57BL6 mice were inoculated with 5 x 10(5) cells/2.5 microl of cells from the Queens, B16F10, or B16LS9 melanoma cell lines. The right eyes were enucleated at 7 days, and the mice were sacrificed at 28 days postinoculation, respectively. Hepatic micrometastases were counted. There were four treatment groups (n = 15 each) for each cell line as follows: group 1, intraperitoneal injections of 20 KIU interferon alpha -2b for 4 days prior to enucleation; group 2, intramuscular injections of 100 microl 0.1 microg/microl murine angiostatin every day for 14 days starting on day 1 after enucleation; group 3, treatment of group 1 and group 2 combined; group 4, intraperitoneal and intramuscular injections of equal volumes of phosphate-buffered saline (PBS) (control group).

RESULTS

Results showed decreased micrometastases for groups 1 through 3 compared with group 4, with the greatest reduction in group 3 (p < 0.006).

CONCLUSIONS

This study suggests that combined neoadjuvant interferon alpha -2b and adjuvant low-dose angiostatin therapy act synergistically to decrease hepatic micrometastases in a murine ocular melanoma model.

The relation between c-myc expression and interferon sensitivity in uveal melanoma

BACKGROUND/AIM

Interferons (IFN) are currently being used to treat melanoma, including some patients with uveal melanoma. IFN is thought to inhibit tumour growth through downregulation of the c-myc oncogene; the overexpression of which has been shown to be associated with resistance in cell lines. The aim of this study was to investigate the relation between c-myc gene expression and IFN sensitivity in a series of uveal melanomas in a short term chemosensitivity assay.

METHODS

Tumours from 45 patients with uveal melanoma who had undergone enucleation were studied. The ATP chemosensitivity assay was used to study sensitivity to IFN-alpha-2b in freshly isolated cells from each tumour. Flow cytometry was used to assess c-myc expression in formalin fixed material from the primary specimens.

RESULTS

There was a wide range of IFN sensitivity between the specimens whereas c-myc expression was universal and present in 80% of the tumour cells in 80% of the specimens. Higher c-myc expression was associated with IFN-alpha resistance as measured by the maximum percentage of inhibition (p = 0.05) and there was a trend with the IFN sensitivity index (p = 0.07).

CONCLUSIONS

These results demonstrate that tumours with high c-myc expression are also associated with IFN resistance. Future research is required to explore the potential of c-myc gene manipulation combined with IFN therapy.

Membrane topography of HLA I, HLA II, and ICAM-1 is affected by IFN-γ in lipid rafts of uveal melanomas

The lateral distribution and colocalization of HLA I, HLA-DR, and ICAM-1 proteins was studied for the first time in the plasma membrane of two human uveal melanoma cell lines, OCM-1 and OCM-3. Our fluorescence resonance energy transfer and confocal laser scanning microscopic experiments revealed that these molecules are mostly confined to the same membrane regions, where they form similar protein patterns (homo- and hetero-associates) to those found previously on other cell types of lymphoid as well as colorectal carcinoma origin. Confocal microscopic colocalization experiments with GM(1) gangliosides and the GPI-anchored CD59 molecules showed enrichment of HLA I, HLA-DR, and ICAM-1 molecules in specific membrane domains (lipid rafts) excluding the transferrin receptor. IFN-gamma remarkably increased the expression levels of these molecules and rearranged their association patterns, which can affect the adoptive immune response of effector cells.

High frequency of allele-specific down-regulation of HLA class I expression in uveal melanoma cell lines

Uveal melanoma is the most common primary intra-ocular tumor in adults and has a high mortality rate due to liver metastases, for which no effective treatment is available. To investigate whether immunotherapy might be feasible in uveal melanoma, the HLA class I surface expression of 6 uveal melanoma cell lines was analyzed by flow cytometry using a broad panel of allele-specific monoclonal antibodies. To up-regulate HLA expression, cells were also cultured with IFN-alpha or -gamma. In general, expression of HLA-A alleles was high (except for cell line EOM-3) and could be further up-regulated by both IFN-alpha and -gamma. In cell line EOM-3, IFN-gamma treatment resulted in significant HLA-A expression while IFN-alpha treatment did not. Expression of HLA-B alleles was low or even negative. Variable effects were observed after IFN treatment. In 3 cell lines, expression of some HLA-B alleles could not be induced by IFN-alpha or -gamma: HLA-B44 in cell line 92-1, HLA-B15 in cell line OCM-1 and HLA-B5 in cell line MEL-202. The other B alleles of these cell lines showed enhanced expression levels upon IFN stimulation. In OMM-1 cells, IFN-alpha and -gamma increased the expression of HLA-A but did not induce expression of the 2 B alleles, indicating an HLA-B locus-specific loss. We thus found a high frequency of allele-specific and locus-specific down-regulation of HLA expression in uveal melanoma cell lines. Some of these defects were not restored by IFN-alpha or -gamma treatment. The lack of HLA expression may explain why uveal melanoma cells escape immune surveillance by cytotoxic T cells and complicate the development of immunotherapy in uveal melanoma.

Lack of effect of different cytokines on expression of membrane-bound regulators of complement activity on human uveal melanoma cells

Tumor cells are protected from antibody-dependent complement-mediated lysis by membrane-bound regulators of complement activation (m-RCA). m-RCA are expressed on uveal melanoma cells. We determined whether cytokine treatment affects expression of m-RCA on these cells in vitro. m-RCA expression on uveal melanoma cell lines was studied by flow cytometry, using monoclonal antibodies directed against CD46, CD55, and CD59. Cytokines studied were interferon-alpha (IFN-alpha), IFN-gamma, interleukin-1B (IL-1B), IL-12, and tumor necrosis factor-alpha (TNF-alpha). All three m-RCA were expressed on the uveal melanoma cell lines (CD59>>CD46>CD55), although in variable amounts. With a few exceptions, the cytokines had no effect on m-RCA expression. CD55 expression was not influenced by any of the cytokines. IFN-gamma downregulated expression of CD46 on one cell line (p < 0.01). TNF-alpha upregulated CD59 expression on two of the five cell lines (p < 0.012 and p < 0.001, respectively), which effect was dose dependent. IFN-alpha, IFN-gamma, IL1-beta, IL12, and TNF-alpha had limited effects on m-RCA expression on uveal melanoma cells in vitro.

Melanoma specific Th1 cytotoxic T lymphocyte lines in Vogt-Koyanagi-Harada disease

AIMS/BACKGROUND

To determine the functional properties and cytokine production profiles of melanoma specific cytotoxic T lymphocytes (CTLs) induced from peripheral blood leucocytes of two patients with Vogt-Koyanagi-Harada disease (VKH).

METHODS

Melanoma specific CTL lines were established by long term coculture with a human melanoma cell line (P-36). Cytotoxic activity against P-36 was measured by 51Cr release. The involvement of human leucocyte antigen (HLA) class I or class II molecules in the cytotoxicity of the CTL lines against P-36 was analysed using anti-HLA class I or anti-HLA class II monoclonal antibody (MAb). Surface molecules of CTL lines were analysed by flow cytometry using MAbs specific for CD4, CD8, CD16, CD25, CD56, HLA-DR, T cell antigen receptor (TCR) alpha beta and TCR gamma delta. Cytokine production and soluble interleukin 2 receptor (sIL-2R) secretion were determined by enzyme linked immunosorbent assays. mRNAs of cytokines were analysed using reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

CTLs showed strong cytotoxic activity against P-36. The CTL activity of the cell lines against P-36 was inhibited by the anti-HLA-DR MAb, whereas the MAb specific for monomorphic determinants of HLA-A, B, and C failed to block lytic activity. Flow cytometry identified the following surface molecules: CD4+, CD8-, CD16-, CD25+, CD56-, HLA-DR+, TCR alpha beta +, and TCR gamma delta-. CTLs constitutively produced a high level of IL-6. IL-6 production and sIL-2R secretion of CTLs were enhanced when CTLs were stimulated with P-36. CTLs also produced high levels of interferon gamma (IFN-gamma) and IL-2, but not IL-4. mRNAs of IL-2 and IFN-gamma were detected by RT-PCR in the CTLs.

CONCLUSIONS

Melanoma specific HLADR restricted T helper 1 (Th1) CTLs may play a role in the immunopathogenesis of VKH.

HLA antigen expression on uveal melanoma cells in vivo and in vitro

Immunotherapy with cytokines may be an additional option in the treatment of primary uveal melanoma or melanoma metastases. A study of the effect of cytokines on cultured uveal melanoma cells may predict the effect that cytokines may have in vivo. Knowledge about the influence of cytokines on HLA expression may be especially beneficial, as HLA expression is essential for immune recognition. However, little is known about the normal expression of the HLA antigens on uveal melanoma cells in tissue culture. We therefore determined the HLA expression on short-term cultures of uveal melanoma cells and compared the results to the expression on tissue sections of the original tumors. In vivo and in vitro expression of the monomorphic HLA class I determinants and of HLA-A (R = 0.77) correlated well. A slightly lower agreement was observed for expression of HLA-B (R = 0.68). In vitro growth was associated with a decrease in expression of the class II determinant HLA-DR. We conclude that expression of HLA class I on cultured melanoma cells corresponds to the expression on the original tumor, allowing the applicability of cultured cells as predictors of responsiveness to cytokines in vivo.