Angiogenic profile of uveal melanoma

Identification of feature genes and molecular mechanisms involved in cell communication in uveal melanoma through analysis of single‑cell sequencing data

Uveal melanoma (UM) is a highly metastatic cancer with resistance to immunotherapy. The present study aimed to identify novel feature genes and molecular mechanisms in UM through analysis of single-cell sequencing data. For this purpose, data were downloaded from The Cancer Genome Atlas and National Center for Biotechnology Information Gene Expression Omnibus public databases. The statistical analysis function of the CellPhoneDB software package was used to analyze the ligand-receptor relationships of the feature genes. The Metascape database was used to perform the functional annotation of notable gene sets. The randomForestSRC package and random survival forest algorithm were applied to screen feature genes. The CIBERSORT algorithm was used to analyze the RNA-sequencing data and infer the relative proportions of the 22 immune-infiltrating cell types. In vitro, small interfering RNAs were used to knockdown the expression of target genes in C918 cells. The migration capability and viability of these cells were then assessed by gap closure and Cell Counting Kit-8 assays. In total, 13 single-cell sample subtypes were clustered by t-distributed Stochastic Neighbor Embedding and annotated by the R package, SingleR, into 7 cell categories: Tissue stem cells, epithelial cells, fibroblasts, macrophages, natural killer cells, neurons and endothelial cells. The interactions in NK cells|Endothelial cells, Neurons|Endothelial cells, CD74_APP, and SPP1_PTGER4 were more significant than those in the other subsets. T-Box transcription factor 2, tropomyosin 4, plexin D1 (PLXND1), G protein subunit α I2 (GNAI2) and SEC14-like lipid binding 1 were identified as the feature genes in UM. These marker genes were found to be significantly enriched in pathways such as vasculature development, focal adhesion and cell adhesion molecule binding. Significant correlations were observed between key genes and immune cells as well as immune factors. Relationships were also observed between the expression levels of the key genes and multiple disease-related genes. Knockdown of PLXND1 and GNAI2 expression led to significantly lower viability and gap closure rates of C918 cells. Therefore, the results of the present study uncovered cell communication between endothelial cells and other cell types, identified innovative key genes and provided potential targets of gene therapy in UM.

Impact of Nintedanib and Anti-Angiogenic Agents on Uveal Melanoma Cell Behavior

Purpose

The purpose of this study was to investigate the direct impact of the combined angiokinase inhibitor nintedanib as well as the anti-angiogenic agents ranibizumab, bevacizumab, and aflibercept on the primary uveal melanoma (UM) cell line Mel270 and liver metastasis UM cell line OMM2.5.

Methods

The metabolic activity, viability, and oxidative stress levels were analyzed by the Thiazolyl Blue Tetrazolium Bromide (MTT), LIVE/DEAD, and reactive oxygen species (ROS) assays. Expression of intracellular VEGF-A165 and VEGF receptor-2 was detected by immunofluorescent staining. The secretion of VEGF-A165 into the cell culture supernatants was evaluated by VEGF-A165 ELISA.

Results

Nintedanib, at a concentration of 1 µg/mL, resulted in a median reduction of metabolic activity (for Mel270 of approximately 38% and for OMM2.5 of 46% compared to the untreated control) without exerting toxicity in either cell line, whereas the other 3 substances did not result in any changes (which also means that none of the 4 substances led to an increased cell death). Moreover, nintedanib (1 µg/mL) induced oxidative stress in the Mel270 by approximately 1.2 to 1.5-fold compared to the untreated control, but not the OMM2.5 cells.

Conclusions

Nintedanib could suppress the growth of UM cells in a concentration-dependent manner. The metastatic UM cell line OMM2.5 was not sensitive to the pro-oxidant activity of nintedanib. This study was the first to investigate nintedanib in the context of UM. We propose further investigation of this substance to elucidate its effects on this tumor entity with the hope of identifying advantageous therapeutic options for future adjuvant tumor therapies.

Identification and validation of immunogenic cell death-related score in uveal melanoma to improve prediction of prognosis and response to immunotherapy

BACKGROUND

Immunogenic cell death (ICD) could activate innate and adaptive immune response. In this work, we aimed to develop an ICD-related signature in uveal melanoma (UVM) patients and facilitate assessment of their prognosis and immunotherapy.

METHODS

A set of machine learning methods, including non-negative matrix factorization (NMF) method and least absolute shrinkage and selection operator (LASSO) logistic regression model, and bioinformatics analytic tools were integrated to construct an ICD-related risk score (ICDscore). CIBERSORT and ESTIMATE algorithms were used to evaluate the infiltration of immune cells. The Genomics of Drug Sensitivity in Cancer (GDSC), cellMiner and tumor immune dysfunction and exclusion (TIDE) databases were used for therapy sensitivity analyses. The predictive performance between ICDscore with other mRNA signatures was also compared.

RESULTS

The ICDscore could predict the prognosis of UVM patients in both the training and four validating cohorts. The ICDscore outperformed 19 previously published signatures. Patients with high ICDscore exhibited a substantial increase in immune cell infiltration and expression of immune checkpoint inhibitor-related genes, leading to a higher response rate to immunotherapy. Furthermore, the downregulation of poly (ADP-ribose) polymerase family member 8 (PARP8), a critical gene involved in the development of the ICDscore, resulted in decreased cell proliferation and slower migration of UVM cells.

CONCLUSION

In conclusion, we developed a robust and powerful ICD-related signature for evaluating the prognosis and benefits of immunotherapy that could serve as a promising tool to guide decision-making and surveillance for UVM patients.

Inhibition of CD146 lessens uveal melanoma progression through reducing angiogenesis and vasculogenic mimicry

PURPOSE

Anti-angiogenesis drug therapy is ineffective in treating uveal melanoma since it only targets angiogenesis leaving vasculogenic mimicry aside. There is no effective clinical strategy targeting vasculogenic mimicry, yet. We show here that CD146 is a novel target to inhibit uveal melanoma progression since it regulates both uveal melanoma angiogenesis and vasculogenic mimicry activity.

METHODS

CD146 inhibition was achieved with its specific siRNAs or antibody AA98. Tube formation and migration of primary human retinal microvascular endothelial cells and tube-like structure formation, migration, invasion of uveal melanoma cells were evaluated after CD146 inhibition. The underlying mechanisms were investigated by Western blot and immunofluorescence. Finally, uveal melanoma cells were injected subretinally into the eyes of nude mice and AA98 was administrated. Tumor size was revealed by H&E staining, and angiogenesis and vasculogenic mimicry were evaluated with CD31-PAS staining.

RESULTS

CD146 inhibition induced declines in tube formation and migration of primary human retinal microvascular endothelial cells and tube-like structure formation of uveal melanoma cells. CD146 mediated VEGFR/AKT/p38/NF-κB and FAK/VE-cadherin signal cascades were partially responsible for these biological effects. CD146 blockade by siRNA or AA98 also resulted in inhibition of migration and invasion as well as EMT process of uveal melanoma cells. The physiological relevance of such declines was confirmed by showing that AA98 treatment markedly suppressed the tumor growth, angiogenesis and vasculogenic mimicry induced by implantation of uveal melanoma cells into the eyes of nude mice.

CONCLUSIONS

CD146 is a novel mediator of both angiogenesis and vasculogenic mimicry in uveal melanoma. Its antibody AA98 has the potency to be developed as a new antibody drug for treating uveal melanoma. Our results warrant further assessment of CD146 as a potential target to improve therapeutic management of uveal melanoma in a clinical setting.

Systemic and liver-directed therapies in metastatic uveal melanoma: state-of-the-art and novel perspectives

Metastatic uveal melanoma (MUM) is the most common form of noncutaneous melanoma. It is different from its cutaneous counterpart and is characterized by a very poor prognosis. Despite groundbreaking improvements in the treatment of cutaneous melanoma, there have been few advances in the treatment of MUM, and standard treatments for MUM have not been defined. We performed a systematic review focusing our attention on all interventional studies, ongoing or already published, concerning the treatment of MUM. We present results from studies of chemotherapy, targeted therapy, immunotherapy and liver-directed therapies. Although the results in this setting have been disappointing until now, trials investigating novel immunotherapeutic strategies alone and in combination with targeted agents and liver-directed therapies are ongoing.

Hypoxia-dependent drivers of melanoma progression

Hypoxia, a condition of low oxygen availability, is a hallmark of tumour microenvironment and promotes cancer progression and resistance to therapy. Many studies reported the essential role of hypoxia in regulating invasiveness, angiogenesis, vasculogenic mimicry and response to therapy in melanoma. Melanoma is an aggressive cancer originating from melanocytes located in the skin (cutaneous melanoma), in the uveal tract of the eye (uveal melanoma) or in mucosal membranes (mucosal melanoma). These three subtypes of melanoma represent distinct neoplasms in terms of biology, epidemiology, aetiology, molecular profile and clinical features.In this review, the latest progress in hypoxia-regulated pathways involved in the development and progression of all melanoma subtypes were discussed. We also summarized current knowledge on preclinical studies with drugs targeting Hypoxia-Inducible Factor-1, angiogenesis or vasculogenic mimicry. Finally, we described available evidence on clinical studies investigating the use of Hypoxia-Inducible Factor-1 inhibitors or antiangiogenic drugs, alone or in combination with other strategies, in metastatic and adjuvant settings of cutaneous, uveal and mucosal melanoma.Hypoxia-Inducible Factor-independent pathways have been also reported to regulate melanoma progression, but this issue is beyond the scope of this review.As evident from the numerous studies discussed in this review, the increasing knowledge of hypoxia-regulated pathways in melanoma progression and the promising results obtained from novel antiangiogenic therapies, could offer new perspectives in clinical practice in order to improve survival outcomes of melanoma patients.

MicroRNA-145 suppresses uveal melanoma angiogenesis and growth by targeting neuroblastoma RAS viral oncogene homolog and vascular endothelial growth factor

BACKGROUND

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. It has been demonstrated that microRNA-145 (miR-145) is correlated with the progression of various cancers by regulating the expression of multiple target genes, especially a number of genes that regulate angiogenesis and proliferation. However, the underlying mechanisms of miR-145 in tumor angiogenesis of UM are still not well illustrated. Thus, we aimed to explore the potential target genes or pathways regulated by miR-145 in UM and the effect of miR-145 on invasion and angiogenesis.

METHODS

Totally, 24 choroid samples were collected in our study, including 12 UM samples and 12 normal uveal tissues. The expression of neuroblastoma RAS viral oncogene homolog (N-RAS), phosphorylated protein kinase B (p-AKT), and vascular endothelial growth factor (VEGF) in UM tissues and normal uveal tissues was analyzed using Western blotting analysis. Lentivirus expression system was used to construct MUM-2B and OCM-1 cell lines with stable overexpression of miR-145. Transwell and endothelial cell tube formation assay were used to measure the effects of miR-145 on the invasion and angiogenesis of UM in vitro. The downstream target genes of miR-145 were predicted by bioinformatics and confirmed using a luciferase assay. BALB/c nude mice models were established to investigate the mechanisms of miR-145 on tumor growth and angiogenesis in vivo. Group data comparisons were performed using analysis of Student's t test. A two-tailed P < 0.05 was considered as statistically significant.

RESULTS

The results of Western blotting analysis indicated that the expressions of N-RAS (1.10 ± 0.35 vs. 0.41 ± 0.36, t = 3.997, P = 0.012), p-AKT (1.16 ± 0.22 vs. 0.57 ± 0.03, t = 7.05, P = 0.001), and VEGF (0.97 ± 0.32 vs. 0.45 ± 0.21, t = 3.314, P = 0.008) in UM tumor tissues were significantly higher than those in normal uveal tissue. Luciferase assay demonstrated N-RAS and VEGF as downstream targets of miR-145. Moreover, tube formation assay revealed that miR-145-transfected human microvascular endothelial cell line formed shorter tube length (36.10 ± 1.51 mm vs. 42.91 ± 0.94 mm, t = 6.603, P = 0.003) and less branch points (350.00 ± 19.97 vs. 406.67 ± 17.62, t = 3.685, P = 0.021) as compared with controls. In addition, the numbers of invaded MUM-2B and OCM-1 cells with miR-145 overexpression were significantly lower than the controls (35.7 ± 3.3 vs. 279.1 ± 4.9, t = 273.75, P < 0.001 and 69.5 ± 4.4 vs. 95.6 ± 4.7, t = 21.27, P < 0.001, respectively). In vivo, xenografts expressing miR-145 had smaller sizes (miR-145 vs. miR-scr, 717.41 ± 502.62 mmvs. 1694.80 ± 904.33 mm, t = 2.314, P = 0.045) and lower weights (miR-145 vs. miR-scr, 0.74 ± 0.46 g vs. 1.65 ± 0.85 g, t = 2.295, P = 0.045).

CONCLUSION

Our results indicated that miR-145 is an important tumor suppressor and the inhibitory strategies against N-RAS/VEGF signaling pathway might be potential therapeutic applications for UM in the future.

The Autocrine FGF/FGFR System in both Skin and Uveal Melanoma: FGF Trapping as a Possible Therapeutic Approach

Fibroblast growth factors (FGFs) play non-redundant autocrine/paracrine functions in various human cancers. The Cancer Genome Atlas (TCGA) data mining indicates that high levels of FGF and/or FGF receptor (FGFR) expression are associated with reduced overall survival, chromosome 3 monosomy and BAP1 mutation in human uveal melanoma (UM), pointing to the FGF/FGFR system as a target for UM treatment. Here, we investigated the impact of different FGF trapping approaches on the tumorigenic and liver metastatic activity of liver metastasis-derived murine melanoma B16-LS9 cells that, similar to human UM, are characterized by a distinctive hepatic tropism. In vitro and in vivo experiments demonstrated that the overexpression of the natural FGF trap inhibitor long-pentraxin 3 (PTX3) inhibits the oncogenic activity of B16-LS9 cells. In addition, B16-LS9 cells showed a reduced tumor growth and liver metastatic activity when grafted in PTX3-overexpressing transgenic mice. The efficacy of the FGF trapping approach was confirmed by the capacity of the PTX3-derived pan-FGF trap small molecule NSC12 to inhibit B16-LS9 cell growth in vitro, in a zebrafish embryo orthotopic tumor model and in an experimental model of liver metastasis. Possible translational implications for these observations were provided by the capacity of NSC12 to inhibit FGF signaling and cell proliferation in human UM Mel285, Mel270, 92.1, and OMM2.3 cells. In addition, NSC12 caused caspase-3 activation and PARP cleavage followed by apoptotic cell death as well as β-catenin degradation and inhibition of UM cell migration. Together, our findings indicate that FGF trapping may represent a novel therapeutic strategy in UM.

Tumour Angiogenesis in Uveal Melanoma Is Related to Genetic Evolution

Increased angiogenesis is associated with a higher metastasis- and mortality rate in uveal melanoma (UM). Recently, it was demonstrated that genetic events, such as 8q-gain and BAP1-loss, influence the level of immune infiltrate. We aimed to determine whether genetic events, and specific cytokines, relate to angiogenesis in UM. Data from UM patients who underwent enucleation between 1999 and 2008 were analysed. Microvascular density (MVD) and the presence of infiltrating immune cells were determined with immunohistochemistry (IHC) and immunofluorescence in 43 cases. Chromosome status, BAP1 IHC and mRNA expression of angiogenesis-related genes were known in 54 cases. Tumours with monosomy 3/BAP1-loss showed a higher MVD compared to tumours with disomy 3/normal BAP1 expression (p = 0.008 and p = 0.004, respectively). Within BAP1-positive lesions (n = 20), 8q-gain did not relate to MVD (p = 0.51). A high MVD was associated with an increased expression of angiopoietin 2 (ANGPT2) (p = 0.041), Von Willebrand Factor (VWF) (p = 0.010), a decreased expression of vascular endothelial growth factor B (VEGF-B) (p = 0.024), and increased numbers of tumour-infiltrating macrophages (CD68+, p = 0.017; CD68+CD163+, p = 0.031) and lymphocytes (CD4+, p = 0.027). Concluding, vascular density of UM relates to its genetic profile: Monosomy 3 and BAP1-loss are associated with an increased MVD, while an early event (gain of 8q) is not independently related to MVD, but may initiate a preparation phase towards development of vessels. Interestingly, VEGF-B expression is decreased in UM with a high MVD.

Targeted Therapy of Uveal Melanoma: Recent Failures and New Perspectives

Among Uveal Melanoma (UM) driver mutations, those involving GNAQ or GNA11 genes are the most frequent, while a minor fraction of tumors bears mutations in the PLCB4 or CYSLTR2 genes. Direct inhibition of constitutively active oncoproteins deriving from these mutations is still in its infancy in UM, whereas BRAFV600E-targeted therapy has obtained relevant results in cutaneous melanoma. However, UM driver mutations converge on common downstream signaling pathways such as PKC/MAPK, PI3K/AKT, and YAP/TAZ, which are presently considered as actionable targets. In addition, BAP1 loss, which characterizes UM metastatic progression, affects chromatin structure via histone H2A deubiquitylation that may be counteracted by histone deacetylase inhibitors. Encouraging results of preclinical studies targeting signaling molecules such as MAPK and PKC were unfortunately not confirmed in early clinical studies. Indeed, a general survey of all clinical trials applying new targeted and immune therapy to UM displayed disappointing results. This paper summarizes the most recent studies of UM-targeted therapies, analyzing the possible origins of failures. We also focus on hyperexpressed molecules involved in UM aggressiveness as potential new targets for therapy.

Uveal Melanoma, Angiogenesis and Immunotherapy, Is There Any Hope?

Uveal melanoma is considered a rare disease but it is the most common intraocular malignancy in adults. Local treatments are effective, but the systemic recurrence rate is unacceptably high. Moreover, once metastasis have developed the prognosis is poor, with a 5-year survival rate of less than 5%, and systemic therapies, including immunotherapy, have rendered poor results. The tumour biology is complex, but angiogenesis is a highly important pathway in these tumours. Vasculogenic mimicry, the ability of melanomas to generate vascular channels independently of endothelial cells, could play an important role, but no effective therapy targeting this process has been developed so far. Angiogenesis modulates the tumour microenvironment of melanomas, and a close interplay is established between them. Therefore, combining immune strategies with drugs targeting angiogenesis offers a new therapeutic paradigm. In preclinical studies, these approaches effectively target these tumours, and a phase I clinical study has shown encouraging results in cutaneous melanomas. In this review, we will discuss the importance of angiogenesis in uveal melanoma, with a special focus on vasculogenic mimicry, and describe the interplay between angiogenesis and the tumour microenvironment. In addition, we will suggest future therapeutic approaches based on these observations and mention ways in which to potentially enhance current treatments.

Neddylation Blockade Diminishes Hepatic Metastasis by Dampening Cancer Stem-Like Cells and Angiogenesis in Uveal Melanoma

Purpose: Liver metastasis is the major and direct cause of death in patients with uveal melanoma (UM). There is no effective therapy for patients with metastatic UM. Improved treatments of hepatic metastatic patients with UM were urgently needed. Inspired by readily detectable key components in the neddylation pathway in UM cells, we aimed at exploring whether neddylation pathway was a therapeutic target for liver metastatic UM.Experimental Design: Expression of key proteins in the neddylation pathway in UM was detected by Western blotting, real-time quantitative RT-PCR (qRT-PCR), and immunohistochemical staining. Cellular proliferation, apoptosis, cell cycle, migration, and cancer stem-like cells (CSCs) properties were examined upon treatment with MLN4924, a potent and selective NAE inhibitor. Antitumor activity and frequency of CSCs were determined by using a NOD-SCID mouse xenograft model. Liver metastasis was evaluated by use of a NOD-scid-IL2Rg-/- mouse model.Results: NAE1 expression was readily detectable in UM. Inhibition of the neddylation pathway by MLN4924 repressed the CSCs properties in UM (capacities of tumorsphere formation and serially replating, aldehyde dehydrogenase-positive cells, and frequency of CSC) through Slug protein degradation. MLN4924 treatment disturbed the paracrine secretion of NF-κB-mediated VEGF-C and its dependent angiogenesis. The inhibitory effect of neddylation blockade on proliferation, which was confirmed by xenografted UM tumor in NOD-SCID mice, was involved in activation of ATM-Chk1-Cdc25C DNA damage response, and G₂-M phase arrest. Neddylation inhibition profoundly inhibited hepatic metastasis in UM.Conclusions: Our studies validate the neddylation pathway as a promising therapeutic target for the treatment of patients with hepatic metastasis of UM. Clin Cancer Res; 24(15); 3741-54. ©2017 AACRSee related commentary by Yang et al., p. 3477.

Phase II Trial of Bevacizumab in Combination With Temozolomide as First-Line Treatment in Patients With Metastatic Uveal Melanoma

BACKGROUND

In experimental models, bevacizumab suppressed in vitro growth and in vivo hepatic metastasis of ocular melanoma cells. Additional preclinical data suggested a potential benefit when combining bevacizumab with dacarbazine.

METHODS

This noncomparative phase II study evaluated a combination of bevacizumab (10 mg/kg on days 8 and 22) with temozolomide (150 mg/m(2) on days 1-7 and 15-21) in 36 patients with metastatic uveal melanoma (MUM). The primary endpoint was the progression-free rate (PFR) at 6 months. Using a modified 2-step Fleming plan, at least 10 of 35 patients were required to support a predefined PFR at 6 months of 40%. Secondary objectives were progression-free survival (PFS), overall survival (OS), and safety; liver perfusion computed tomography (CT) for response imaging; and impact of VEGF-A gene polymorphisms on bevacizumab pharmacodynamics.

RESULTS

First- and second-step analyses revealed nonprogression at 6 months in 3 of 17 and 8 of 35 patients, respectively. Finally, the 6-month PFR was 23% (95% confidence interval [CI]: 10-39), with long-lasting stable disease in 5 patients (14%). Median PFS and OS were 12 weeks and 10 months, respectively. No unexpected toxicity occurred. Liver perfusion CT imaging was not useful in assessing tumor response, and VEGF-A gene polymorphisms were not correlated with toxicity or survival.

CONCLUSION

In patients with MUM, a combination of bevacizumab plus temozolomide achieved a 6-month PFR of 23%.

Analysis of caveolin-1 and phosphoinositol-3 kinase expression in primary uveal melanomas

BACKGROUND

To evaluate the regulation of blood supply in primary uveal melanomas through caveolin-1 (Cav-1)/phosphoinositol-3 kinase (PI3K).

METHODS

The expression of Cav-1 and PI3K was analysed in 51 paraffin sections of metastatic (n = 30) and non-metastastic uveal melanomas (n = 21). Two trained observers quantified Cav-1 and PI3K immunofluorescensce expression by determining intensity of staining and percentage of positive cells. The expression was correlated with known prognostic factors. Besides angiogenesis by means of endoglin expression, the normal vasculature (von Willebrand Factor expression) was evaluated semi-quantitatively. Vasculogenic mimicry (VM) was analysed by CD31/PAS staining.

RESULTS

All examined specimens expressed Cav-1 with a mean of 90.34% Cav-1 positive cells (range, 3.23-100%). Metastatic disease was associated with a higher Cav-1 expression. The correlation of Cav-1 with well-established prognostic factors showed a significant association between Cav-1 expression and largest tumour diameter (P = 0.022), tumour node metastasis classification (P = 0.008) and invasion of optic nerve head (P = 0.048). PI3K was expressed by all uveal melanomas with a mean of 87.28% cells showing PI3K expression. A higher level of PI3K was significantly associated with larger height (P = 0.042) and progressed tumour node metastasis stage (P = 0.016). The percentage of PI3K and Cav-1 positive cells were significantly associated (P = 0.034). For PI3K and Cav-1 expression a non-significant association with VM was shown (P = 0.064 and P = 0.072, respectively). No correlation of PI3K or Cav-1 with angiogenesis or mature vasculature was seen (P > 0.05).

CONCLUSIONS

Cav-1 expression may be especially up-regulated in larger uveal melanomas. As it was correlated with PI3K expression and VM in this series of uveal melanoma, Cav-1 might induce the formation of VM via the PI3K-signalling cascade.

Establishment and Characterization of Orthotopic Mouse Models for Human Uveal Melanoma Hepatic Colonization

Uveal melanoma (UM) is a rare type of melanoma, although it is the most common primary ocular malignant tumor in adults. Nearly one-half the patients with primary UM subsequently develop systemic metastasis, preferentially to the liver. Currently, no treatment is effective for UM hepatic metastasis, and the prognosis is universally poor. The main challenge in designing a treatment strategy for UM hepatic metastasis is the lack of suitable animal models. We developed two orthotopic mouse models for human UM hepatic metastases: direct hepatic implantation model (intrahepatic dissemination model) and splenic-implantation model (hematogenous dissemination model) and investigated the tumorgenesis in the liver. A human UM cell line, established from a hepatic metastasis and nonobese diabetic severe combined immunodeficient γ mice, were used for development of in vivo tumor models. In the direct hepatic implantation model, a localized tumor developed in the liver in all cases and intrahepatic dissemination was subsequently seen in about one-half of cases. However, in the splenic implantation model, multiple hepatic metastases were observed after splenic implantation. Hepatic tumors subsequently seeded intra-abdominal metastasis; however, lung metastases were not seen. These findings are consistent with those observed in human UM hepatic metastases. These orthotopic mouse models offer useful tools to investigate the biological behavior of human UM cells in the liver.

Subtoxic Levels of Apigenin Inhibit Expression and Secretion of VEGF by Uveal Melanoma Cells via Suppression of ERK1/2 and PI3K/Akt Pathways

The effects of apigenin on the expression of VEGF in uveal melanoma cells have not been reported. We studied this effect and relevant signaling pathways in two human uveal melanoma cell lines (SP6.5 and C918). ELISA assay revealed that the constitutive secretion of VEGF by uveal melanoma cells was 21-fold higher than that in normal uveal melanocytes. Apigenin at subtoxic levels (1-5  μ M) significantly suppressed the secretion of VEGF in a dose- and time-dependent manner in melanoma cells. VEGF levels in the conditioned culture media from SP6.5 and C918 cell lines treated with 5  μ M apigenin for 24 h reduced to 29% and 21% of those in cells not treated with apigenin, respectively. RT-PCR analysis found that apigenin also decreased the expression of VEGF mRNA in melanoma cells. ELISA study of various signal pathways showed that apigenin significantly decreased phosphorylated Akt and ERK1/2 but increased phosphorylated JNK1/2 and p38 MAPK levels in melanoma cells. PI3K/Akt or ERK1/2 inhibitors significantly decreased, but JNK1/2 and p38 MAPK inhibitors did not influence the secretion of VEGF by melanoma cells, suggesting that apigenin suppresses the secretion of VEGF mainly through the inhibition of PI3K/Akt and ERK1/2 pathways.

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.

Intraocular activation of angiogenic and inflammatory pathways in uveal melanoma

PURPOSE

To identify and quantify angiogenic and inflammatory cytokines in aqueous and vitreous humor in eyes with untreated uveal melanoma and to analyze clinicopathologic correlations.

METHODS

Intraocular fluid samples of patients (uveal melanoma aqueous n = 21, vitreous n = 34) and controls (cataract aqueous n = 41, vitreomacular traction aqueous n = 35, vitreous n = 36) were taken intraoperatively and analyzed using Luminex xMAP suspension array technology. Beadlyte kits were used for detection of 28 different cytokines.

RESULTS

Flt-3 ligand, interleukin (IL) 1α, IL-6, IL-8, interferon-γ inducible protein (IP)-10, monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein 1α, platelet-derived growth factor AA, and vascular endothelial growth factor were significantly elevated in aqueous and vitreous of melanoma eyes when compared with controls. Eotaxin was significantly elevated in aqueous, and IL-7 and RANTES were significantly elevated in vitreous samples of melanoma eyes. Interferon-γ inducible protein 10, macrophage inflammatory protein 1α (aqueous and vitreous), Flt-3 ligand, IL-6, IL-8, and MCP-1 (vitreous) correlated with tumor dimensions. Further correlations were found between infiltration of Bruch membrane and Flt-3 ligand, MCP-1 (aqueous and vitreous), IL-8, interferon-γ inducible protein 10, macrophage inflammatory protein 1α, and platelet-derived growth factor AA (vitreous). Analyzing 16 paired aqueous and vitreous melanoma samples, Flt-3 ligand, IL-7, interferon-γ inducible protein 10, MCP-1, and platelet-derived growth factor AA were significantly elevated in vitreous, and IL-1α and vascular endothelial growth factor in aqueous samples.

CONCLUSION

A range of significantly elevated angiogenic, inflammatory, and chemotactic cytokines in eyes with uveal melanoma supports the link between inflammation and tumorigenesis.

A pilot study of bevacizumab and interferon-α2b in ocular melanoma

OBJECTIVES

We hypothesized that administration of bevacizumab, a monoclonal antibody that neutralizes vascular endothelial growth factor, in combination with high-dose interferon-alpha2b (IFN-α2b), an inhibitor of basic fibroblast growth factor, would have clinical activity in patients with metastatic ocular melanoma.

METHODS

Patients with metastatic ocular melanoma received bevacizumab (15 mg/kg intravenously every 2 weeks) plus IFN-α2b (5 MU/m subcutaneously 3 times weekly for 2 weeks followed by a dose of 10 MU/m subcutaneously thereafter). Patients exhibiting a clinical response or stabilization of disease were treated until disease progression.

RESULTS

In this pilot study, 5 patients were treated (3 men, 2 women) with a mean age of 63.8 years (range, 53-71 years). Overall, the regimen was well-tolerated. The following adverse events were noted: grade 3 dyspnea (2 patients), grade 3 and 4 fatigue (2), grade 3 muscle weakness (1), grade 3 anorexia (1), grade 1 and 2 proteinuria (2), and grade 3 diarrhea (1). All adverse events resolved with a treatment holiday or dose reduction. One patient had reduction in tumor burden of 23% by Response Evaluation Criteria in Solid Tumors criteria and 2 patients had stabilization of disease lasting 28 and 36 weeks, respectively. Two patients failed to respond and progressed after 6 and 7 weeks of therapy.

CONCLUSION

Bevacizumab and IFN-α2b were well tolerated in this patient population, and clinical activity was observed. Further study of high-dose IFN-α2b in combination with bevacizumab in this setting is warranted.

Serum vascular endothelial growth factor (VEGF) levels correlate with number and location of micrometastases in a murine model of uveal melanoma

BACKGROUND

A preliminary animal study was performed to determine if hepatic micrometastases from uveal melanoma secrete vascular endothelial growth factor (VEGF) that is measurable in serum.

METHODS

We analysed the serum of a C57Bl/6 mouse model of uveal melanoma (n=10) at days 4, 7, 14 and 21 post-inoculation for VEGF levels. We compared the serum VEGF levels with the number and location of hepatic micrometastases and their respective expression of VEGF mRNA.

RESULTS

Serum VEGF levels rose after inoculation of C57Bl/6 mice eyes with B16LS9 cutaneous melanoma cells. Beginning on day 14 there was a statistically significant (p<0.05) increase in VEGF levels, rising to an average peak level of 37.985 pg/ml at day 21. Peak serum VEGF levels correlated with the total number of hepatic micrometastases (R=0.444) and there was moderate correlation of peak VEGF serum levels with micrometastases in more hypoxic locations (R=0.572). VEGF mRNA expression by micrometastases was highest in the most hypoxic regions of the hepatic lobule.

CONCLUSIONS

Hepatic micrometastastic melanoma arising in a mouse model of ocular melanoma secretes VEGF. The number and location of the micrometastases correlate with serum VEGF levels.

A mutated EGFR is sufficient to induce malignant melanoma with genetic background-dependent histopathologies

Melanoma is a tumor with a very low cure rate once metastasized. Although many genes important for melanoma induction, transformation, and metastasis have been identified, the process of melanomagenesis is only partly understood. Melanoma mediators are easiest to investigate in cell culture models, but animal models are required to evaluate their importance in the context of the whole organism. Here, we describe a transgenic melanoma model in medaka. The oncogenic receptor tyrosine kinase, Xmrk, responsible for melanoma formation in Xiphophorus, was stably expressed under the control of a pigment cell-specific promoter. The transgenic fish developed pigment cell tumors with a penetrance of 100%. The model was used for monitoring the in vivo relevance of several apoptosis and differentiation genes, and for induction of melanoma-relevant signal transduction pathways. We found that Stat5 activation, and Mitf and Bcl-2 levels correlated with a more aggressive stage of the malignancy. Interestingly, different types of pigment cell tumors occurred depending on the genetic background, namely invasive melanoma, uveal melanoma, or exophytic and less aggressive pigment cell tumors called xanthoerythrophoroma. Furthermore, on p53 mutant background, the expression of xmrk led to the appearance of giant focal pigment cell tumors, whereas tumor onset was unchanged compared with wild-type medaka.

Differential effects of imatinib mesylate against uveal melanoma in vitro and in vivo

Uveal melanoma is refractory to chemotherapy. The receptor tyrosine kinase inhibitor, imatinib mesylate, has demonstrated antiproliferative effects against uveal melanoma cells in vitro. The effects of imatinib mesylate, alone and combined with the alklyating agent, temozolomide, were examined in vivo as well as in vitro. Proliferation and angiogenic factor production of human uveal melanoma cell lines in response to imatinib mesylate and temozolomide were examined in vitro. Tumor growth, angiogenic factor production, tumor interstitial fluid pressure, and stroma constituents in response to imatinib mesylate and temozolomide were examined in vivo in mice bearing human uveal melanoma xenografts. Imatinib mesylate in vitro antagonized the antiproliferative effects of temozolomide and increased the production of angiogenic factors. In contrast, pretreatment with imatinib mesylate in vivo could improve the antitumor activity of temozolomide. Imatinib mesylate in vivo decreased the production of angiogenic factors in the tumor stroma and tumor interstitial fluid pressure. These effects were transient. Increases in angiogenic factors, interstitial fluid pressure, and tumor infiltrating macrophages were observed with continued imatinib mesylate treatment in vivo. The antitumor effects of imatinib mesylate can vary in vivo when compared with in vitro. Imatinib mesylate can both positively and negatively modify host-tumor interactions in uveal melanoma.

A novel vector system for gene transfer into the cornea using a partially dried plasmid expressing 18 basic fibroblast growth factor-synthetic amphiphile INTeraction-18 (SAINT-18) complex

PURPOSE

We describe a novel vector system of nonviral gene transfer into the cornea using a partially dried form of a plasmid expressing 18-kDa basic fibroblast growth factor (p-bFGF)-synthetic amphiphile INTeraction-18 (SAINT-18) complex.

METHODS

Corneal neovascularization (NV) was evaluated in 48 eyes of Sprague-Dawley rats after implantation of SAINT-18 containing 2 micro g of plasmid-expressing green fluorescent protein (p-GFP; control group), 0.2 micro g, 2 micro g, or 20 micro g of p-bFGF from day 0 to day 60. bFGF protein expression was analyzed by Western blotting and immunohistochemistry.

RESULTS

The p-bFGF-SAINT-18 complex induced dose-dependent corneal neovascularization, which reached a maximum on days 15-21 in the 20-micro g p-bFGF group, days 12-18 in the 2-micro g p-bFGF group, and on days 9-15 in the 0.2-micro g p-bFGF group, and then regressed progressively. No NV was observed in the p-GFP group.

CONCLUSIONS

This noninflammatory corneal transfection model using partially dried p-bFGF-SAINT-18 complex allows precise localization of tranfection reagents for producing corneal neovascularization.

Targeted therapy for uveal melanoma

Uveal melanoma is the most common primary intra-ocular malignancy in adults. Overall mortality rate remains high because of the development of metastatic disease, which is highly resistant to systemic therapy. Improved understanding of the molecular pathogenesis of cancers has led to a new generation of therapeutic agents that interfere with a specific pathway critical in tumor development or progression. Although no specific genes have been linked to the pathogenesis of uveal melanoma, which differs from that of cutaneous melanoma, progress has been made in identifying potential targets involved in uveal melanoma apoptosis, proliferation, invasion, metastasis, and angiogenesis. This review focuses on the prospects for improving the systemic therapy of uveal melanoma using molecularly targeted agents that are currently in clinical use as well as agents being tested in clinical trials. Preclinical studies suggest potential benefit of inhibitors of Bcl-2, ubiquitin-proteasome, histone deactylase, mitogen-activated protein kinase and phosphatidylinositol-3-kinase-AKT pathways, and receptor tyrosine kinases. Modifiers of adhesion molecules, matrix metalloproteinase, and angiogenic factors also have demonstrated potential benefit. Clinical trials of some of these approaches have been initiated in patients with metastatic uveal melanoma as well as in the adjuvant setting after primary therapy.