Animal Models Of Uveal Melanoma Research Articles

Animal Models of Uveal Melanoma.

Animal models are crucial for the study of tumorigenesis and therapies in oncology research. Though rare, uveal melanoma (UM) is the most common intraocular tumor and remains one of the most lethal cancers. Given the limitations of studying human UM cells in vitro, animal models have emerged as excellent platforms to investigate disease onset, progression, and metastasis. Since Greene’s initial studies on hamster UM, researchers have dramatically improved the array of animal models. Animals with spontaneous tumors have largely been replaced by engrafted and genetically engineered models. Inoculation techniques continue to be refined and expanded. Newer methods for directed mutagenesis have formed transgenic models to reliably study primary tumorigenesis. Human UM cell lines have been used to generate rapidly growing xenografts. Most recently, patient-derived xenografts have emerged as models that closely mimic the behavior of human UM. Separate animal models to study metastatic UM have also been established. Despite the advancements, the prognosis has only recently improved for UM patients, especially in patients with metastases. There is a need to identify and evaluate new preclinical models. To accomplish this goal, it is important to understand the origin, methods, advantages, and disadvantages of current animal models. In this review, the authors present current and historic animal models for the experimental study of UM. The strengths and shortcomings of each model are discussed and potential future directions are explored.

Expression of BRCA1-associated protein 1 in primary tumors and metastasis in an animal model of uveal melanoma

Background: Uveal melanoma (UM) is the most common primary intraocular tumor in adults. Despite successful local treatment, approximately 50% of these patients develop lethal metastatic disease. BRCA1-associated protein 1 (BAP1) encodes BAP1, which functions as a tumor suppressor. Inactivation by a somatic mutation in BAP1 results in a loss of protein expression, which is associated with increased risk of metastasis.Aim: To analyze the expression of BAP1 protein in primary uveal tumors and their corresponding metastasis in an animal model of UM and to determine whether BAP1 expression is lost during the metastatic process.Subjects and Methods: Postmortem eyes and lungs with metastasis from nine rabbits previously inoculated with human UM cells expressing BAP1 (92.1 strain) were analyzed. Immunohistochemistry was performed on formalin-fixed paraffin-embedded samples using a monoclonal BAP1 (C-4) antibody. Expression was evaluated by the extent and intensity of staining. All primary tumors and metastasis were positive for BAP1. Results: The staining was diffuse and intense in the primary tumors of four rabbits (67%), focal-intense in one rabbit and focal-mild in one rabbit. All lung metastasis showed focal staining. All animals with intense BAP1 staining in the primary tumor showed mild BAP1 in the metastasis. Discussion: A predominant pattern observed between primary and metastatic lesion shows a transition from moderate into mild intensity and diffuse into the focal extent, suggesting a decrease in BAP1 expression. Future studies, including the human tissue of primary UM and their corresponding metastasis, should be performed to corroborate these findings.

Arylsulfonamide 64B Inhibits Hypoxia/HIF-Induced Expression of c-Met and CXCR4 and Reduces Primary Tumor Growth and Metastasis of Uveal Melanoma.

Uveal melanoma (UM) is the most prevalent and lethal intraocular malignancy in adults. Here, we examined the importance of hypoxia in UM growth and tested the antitumor effects of arylsulfonamide 64B, an inhibitor of the hypoxia-induced factor (HIF) pathway in animal models of UM and investigated the related mechanisms. UM cells were implanted in the uvea of mice eyes and mice systemically treated with 64B. Drug effect on primary eye tumor growth, circulating tumor cells, metastasis formation in liver, and survival were examined. 64B effects on UM cell growth, invasion and hypoxia-induced expression of C-X-C chemokine receptor type 4 (CXCR4) and mesenchymal-epithelial transition factor (c-Met) were measured. Luciferase reporter assays, chromatin immunoprecipitation, co-immunoprecipitation, and cellular thermal shift assays were used to determine how 64B interferes with the HIF transcriptional complex. Systemic administration of 64B had potent antitumor effects against UM in several orthotopic mouse models, suppressing UM growth in the eye (∼70% reduction) and spontaneous liver metastasis (∼50% reduction), and extending mice survival (P < 0.001) while being well tolerated. 64B inhibited hypoxia-induced expression of CXCR4 and c-Met, 2 key drivers of tumor invasion and metastasis. 64B disrupted the HIF-1 complex by interfering with HIF-1α binding to p300/CBP co-factors, thus reducing p300 recruitment to the MET and CXCR4 gene promoters. 64B could thermostabilize p300, supporting direct 64B binding to p300. Our preclinical efficacy studies support the further optimization of the 64B chemical scaffold toward a clinical candidate for the treatment of UM.

Animal Models of Uveal Melanoma for Localized Interventions.

Uveal melanoma is the most common primary intraocular malignancy in adults, carrying a significant risk for death from metastatic disease. Treatment efforts aim toward local tumor control and early detection and management of metastases. Animal models are a valuable tool in the study of the molecular, genetic, and cellular events associated with the development of uveal melanoma and the evaluation of the therapeutic potential for various treatment methods. So far, several spontaneous, transgenetic, or induced animal models have been used, each presenting distinct advantages and disadvantages. This review article systematically presents an analysis of these animal models aimed at localized interventions; We aim to assist researchers with the selection of the optimal animal model based on their particular research targets.

Animal Models of Uveal Melanoma: Methods, Applicability, and Limitations.

Animal models serve as powerful tools for investigating the pathobiology of cancer, identifying relevant pathways, and developing novel therapeutic agents. They have facilitated rapid scientific progress in many tumor entities. However, for establishing a powerful animal model of uveal melanoma fundamental challenges remain. To date, no animal model offers specific genetic attributes as well as histologic, immunologic, and metastatic features of uveal melanoma. Syngeneic models with intraocular injection of cutaneous melanoma cells may suit best for investigating immunologic/tumor biology aspects. However, differences between cutaneous and uveal melanoma regarding genetics and metastasis remain problematic. Human xenograft models are widely used for evaluating novel therapeutics but require immunosuppression to allow tumor growth. New approaches aim to establish transgenic mouse models of spontaneous uveal melanoma which recently provided preliminary promising results. Each model provides certain benefits and may render them suitable for answering a respective scientific question. However, all existing models also exhibit relevant limitations which may have led to delayed research progress. Despite refined therapeutic options for the primary ocular tumor, patients' prognosis has not improved since the 1970s. Basic research needs to further focus on a refinement of a potent animal model which mimics uveal melanoma specific mechanisms of progression and metastasis. This review will summarise and interpret existing animal models of uveal melanoma including recent advances in the field.

Imatinib Mesylate Alters the Expression of Genes Related to Disease Progression in an Animal Model of Uveal Melanoma

Imatinib mesylate (IM) is a compound that inhibits both BCR-ABL tyrosine kinase and c-kit receptors. Tyrosine kinases are important in cellular signaling and mediate major cellular processes such as proliferation, differentiation, apoptosis, attachment, and migration. Twenty-six albino rabbits were injected with 1 × 106 human uveal melanoma (UM) cells (92.1) into the suprachoroidal space. Animals were immunosuppressed (cyclosporin A) over the course of the 12-week experiment and divided into two groups (n = 13). The experimental group received IM once daily by gavage while the control group received a placebo. One animal per group was sacrificed every week after the 2nd week. Upon necropsy, organs were harvested for histopathological examination. Cells from the primary tumors were recultured and tested in proliferation and invasion assays. A PCR array was used to investigate the differences in expression of 84 genes related to tumor metastasis. In the treated group, 4 rabbits developed intraocular tumors, with an average largest tumor dimension (LTD) of 2.5 mm and 5 animals reported metastatic disease. Whereas 6 rabbits in the control group developed intraocular tumors, with an average LTD of 5.8 mm and 6 animals reported metastatic disease. The recultured cells from the treated group demonstrated lower proliferation rates and were less invasive (p &lt; 0.001 The PCR array showed differences in expression of genes related to metastasis. Notably, there was 290-fold increase inSERPINB5, a tumor suppressor gene, and a 10-fold higher expression ofKISS1, a metastasis suppressor gene, in the treated group. Proangiogenic genes such asVEGFA,PDGFAandPDGFBwere downregulated in the treated group. To the best of our knowledge, this is the first report detailing the altered expression of specific genes in UM cells after treatment with IM.

Imatinib mesylate alters the expression of genes related to disease progression in an animal model of uveal melanoma.

Imatinib mesylate (IM) is a compound that inhibits both BCR-ABL tyrosine kinase and c-kit receptors. Tyrosine kinases are important in cellular signaling and mediate major cellular processes such as proliferation, differentiation, apoptosis, attachment, and migration. Twenty-six albino rabbits were injected with 1 × 106 human uveal melanoma (UM) cells (92.1) into the suprachoroidal space. Animals were immunosuppressed (cyclosporin A) over the course of the 12-week experiment and divided into two groups (n = 13). The experimental group received IM once daily by gavage while the control group received a placebo. One animal per group was sacrificed every week after the 2nd week. Upon necropsy, organs were harvested for histopathological examination. Cells from the primary tumors were recultured and tested in proliferation and invasion assays. A PCR array was used to investigate the differences in expression of 84 genes related to tumor metastasis. In the treated group, 4 rabbits developed intraocular tumors, with an average largest tumor dimension (LTD) of 2.5 mm and 5 animals reported metastatic disease. Whereas 6 rabbits in the control group developed intraocular tumors, with an average LTD of 5.8 mm and 6 animals reported metastatic disease. The recultured cells from the treated group demonstrated lower proliferation rates and were less invasive (p < 0.001 The PCR array showed differences in expression of genes related to metastasis. Notably, there was 290-fold increase in SERPINB5, a tumor suppressor gene, and a 10-fold higher expression of KISS1, a metastasis suppressor gene, in the treated group. Proangiogenic genes such as VEGFA, PDGFA and PDGFB were downregulated in the treated group. To the best of our knowledge, this is the first report detailing the altered expression of specific genes in UM cells after treatment with IM.

Fine needle aspiration biopsy to reestablish cell culture in an animal model of uveal melanoma

To access the reliability of fine-needle aspiration biopsy in harvesting a sufficient amount of viable melanoma cells to establish a cell culture and maintain a melanoma cell line from an animal model of uveal melanoma. For this study, fifteen male New Zealand albino rabbits had their right eye surgically inoculated with uveal melanoma cell line 92.1. The animals were immunosupressed with cyclosporine A using a dose schedule previously published. The animals were followed for 12 weeks. Intraocular tumor growth was monitored weekly by indirect ophthalmoscopy. After the fourth week, one animal was sacrificed per week preceded by fine-needle aspiration biopsy using a sharp 25-gauge, 1-inch long needle. Two separate aspirates were made from different areas of the tumor. Each aspirate was flushed to a separate cell culture media and sent for cell culture. The cells were frozen after two weeks when there were at least 1 million cells, which is enough to maintain a cell line. Cells were defrosted for HMB-45 immuno-stains to confirm the melanoma origin. Cell growth was observed from the samples harvested from 11 out of the 15 animals inoculated with uveal melanoma. All cell cultures, after defrost, immunoassayed positive for HMB-45. Fine needle aspiration biopsy seems to be a reliable method to harvest cells from solid intraocular melanomas in an animal model, to establish cell culture and to maintain a melanoma cell line.

Resveratrol Inhibits Uveal Melanoma Tumor Growth via Early Mitochondrial Dysfunction

To test the efficacy of resveratrol, a nontoxic plant product, in the treatment of uveal melanoma. The effect of oral administration and peritumor injection of resveratrol was tested on tumor growth in two animal models of uveal melanoma. The mechanism of resveratrol action on uveal melanoma cells was studied in vitro in a cell-viability assay: with JC-1 dye, to measure mitochondrial membrane potential; by Western blot analysis, to analyze the cellular redistribution of cytochrome c and Smac/diablo; and in a fluorescence assay with specific substrates, to measure activation of different caspases. Resveratrol treatment inhibited tumor growth in animal models of uveal melanoma. Since oral administration resulted in relatively low bioavailability of resveratrol, the effect of increased local levels was tested by peritumor injection of the drug. This method resulted in tumor cell death and tumor regression. In vitro experiments with multiple uveal melanoma cell lines demonstrate that resveratrol causes a decrease in cell viability, resulting at least in part from an increase in apoptosis through a mitochondrial pathway. An early event in drug action is the direct targeting of mitochondria by resveratrol, which leads to a decrease in mitochondrial membrane potential and the eventual activation of caspase-3. These data suggest that resveratrol can inhibit tumor growth and can induce apoptosis via the intrinsic mitochondrial pathway and that by further increasing bioavailability of resveratrol the potency of the drug can be increased, leading to tumor regression. The nontoxic nature of the drug at levels needed for therapy make resveratrol an attractive candidate for the treatment of uveal melanoma.

The effect of Blue‐Light exposure in an ocular melanoma animal model

Abstract Purpose: Uveal melanoma (UM) cells lines, when exposed to blue light in vitro, show a significant increase in proliferation. In order to see if the same effect would be seen in vivo, we investigated the influence of blue‐light exposure in an animal model of UM. Methods: Twenty albino rabbits were injected with 1 million human UM cells (92.1) into the suprachoroidal space of the eye. Animals were immunosuppressed using cyclosporin A throughout the 8 week long experiment. The animals were divided into two groups of 10 animals each. The experimental group was exposed to blue‐light, while the control group was protected from blue‐light using a yellow‐filter. Intraocular tumor growth was evaluated weekly by fundoscopic examination. One animal was sacrificed per week, after the 2nd week, in order to evaluate progression of the disease. The eyes were removed after sacrifice and the proliferation rates of the re‐cultured cells obtained from the intraocular tumors were performed using the Sulfordhamine‐B assay. The Student's t–test was used to compare results for statistical significance. Results: Re‐cultures of UM cells were establish from 4 and 5 rabbits of the experimental and control group respectively. Cells were re‐cultured for a very short period of time (1 passage only) in order to maintain any in vivo cellular changes. The exposure of rabbits to blue light led to an increase in proliferation of the cell lines derived from intraocular tumors compared to the control (p=0.001). Conclusions: There is increasing amount of data suggesting that Blue‐light, one of the components of visible light, may influence the progression of UM. Our results warrant further studies to relate the importance of Blue‐Light filtering lenses for UM patients.

The use of a cyclooxygenase-2 inhibitor (Nepafenac) in an ocular and metastatic animal model of uveal melanoma

The expression of cyclooxygenase-2 (COX-2) has been reported as an indicator of poor prognosis in a wide variety of human tumors, including colon, breast and uveal melanoma (UM). COX-2 inhibitors have shown promise in controlling the malignancy of several types of tumors. Previous studies have demonstrated the efficacy of a COX-2 inhibitor on the proliferation rates of human UM cells. The goal of this experiment was to investigate the efficiency of Nepafenac, a topically administered COX-2 inhibitor, in a rabbit model of UM. The animals were divided into two groups of 14 animals for the duration of the 12-week experiment. One animal per group was killed each week to evaluate disease progression and for histopathological studies. The experimental group received drops containing 0.3% Nepafenac solution. Intraocular tumor growth was evaluated weekly by fundoscopic examination and each animal was weighed prior to examination. Blood samples were taken weekly from all rabbits to detect circulating malignant cells (CMCs) throughout the experiment. After the second week of inoculation, the experimental group weighed significantly more than the control group. The control group developed more intraocular tumors and presented with metastases and higher detectable levels of CMCs before the treated group. These results indicate that the topical administration of a COX-2 inhibitor delayed the progression of this malignancy in our animal model. A clinical trail using an anti-COX-2 inhibitor for patients with UM should be considered.

Experimental models of uveal melanoma

Over the past several decades, considerable effort has been directed toward developing suitable experimental models for the study of uveal melanoma. Animal models of uveal melanoma have undergone many improvements, leading to the development of experimental systems that better represent the disease in human beings. A major advance has come from the use of human uveal melanoma cell lines capable of inducing tumour growth and metastatic disease in immunodeficient hosts. Knowledge gained from the use of experimental models will ultimately be translated into better diagnostic and therapeutic strategies for patients with uveal melanoma. In this review the authors describe the current state-of-the-art designs of experimental models of uveal melanoma, highlighting the advantages and disadvantages of the available models. Novel findings from a rabbit model of uveal melanoma are also presented.

Animal models in uveal melanoma: establishment and research

Experimental models may help elucidate aspects of uveal melanoma, such as the histogenesis, etiology and natural history, that are not yet fully understood. Moreover, the development of experimental models allows testing of new diagnostic methods and treatments to improve the life expectancy and quality of life of affected patients.The author reviews the development of animal models of uveal melanoma and research with animal models examining primary and metastatic uveal melanoma as well as treatments for these tumours and ways to prevent metastasis.

Methods for subchoroidal implantation of Greene melanoma in rabbits.

As an alternative to previously reported treatments, experimental animal models of uveal melanoma provide useful information for assessing the advantage of treatments designed to salvage eyes. Greene melanoma is the best-established model and has been used for the purpose of assessment of several treatments. Various other experimental models that implant melanoma cell lines into the anterior chamber of the rabbit eye have been reported. This article reviews some of the advantages and disadvantages of these experimental models of human uveal melanoma in rabbits and presents a modified subchoroidal implantation procedure for melanoma cells that is used in our laboratory. This procedure effectively, efficiently, and consistently enables us to provide animal models bearing large-sized choroidal melanomas. This modified technique may eventually be applicable to the development of new therapeutic options.

Animal models of uveal melanoma

Many attempts have been made to develop a suitable animal model to study more effectively the aetiology, pathogenesis, diagnosis and therapy of intraocular (uveal) melanoma. Uveal melanoma may spontaneously occur in some animals, including dogs, cats, horses, rats, mice, birds and fish. The histological features, metastatic behaviour and unpredictable nature of occurrence of these uncommon spontaneous tumours detract from their suitability as a model. Several methods have been developed to induce intraocular melanoma chemically or by radiation in laboratory animals. Some of these induced tumours resemble human uveal melanoma, although the majority originate from the retinal pigment epithelium. Uveal proliferations have been biologically induced by feline leukaemia/sarcoma virus and simian virus 40, although the presence of virus in tumour cells and extraocular tumours resulting from shed virus detract from the utility of this model. Inoculation of tissue culture hamster, murine or human melanoma cells into animal eyes has the advantage that the inoculation site and size of inoculum can be controlled. Disadvantages include the immune suppression necessary for tumour growth in some models as well as the fact that many of the melanoma cell lines are of cutaneous origin. Transgenic murine models have been developed using the promoter region of the tyrosinase gene to target expression of oncogenes in melanin-producing cells. Spontaneous intraocular pigmented tumours and distant metastases may occur, although many, if not all, of the intraocular tumours arise in the retinal pigment epithelium.

Animal models of uveal melanoma

Many attempts have been made to develop a suitable animal model to study more effectively the aetiology, pathogenesis, diagnosis and therapy of intraocular (uveal) melanoma. Uveal melanoma may spontaneously occur in some animals, including dogs, cats, horses, rats, mice, birds and fish. The histological features, metastatic behaviour and unpredictable nature of occurrence of these uncommon spontaneous tumours detract from their suitability as a model. Several methods have been developed to induce intraocular melanoma chemically or by radiation in laboratory animals. Some of these induced tumours resemble human uveal melanoma, although the majority originate from the retinal pigment epithelium. Uveal proliferations have been biologically induced by feline leukaemia/sarcoma virus and simian virus 40, although the presence of virus in tumour cells and extraocular tumours resulting from shed virus detract from the utility of this model. Inoculation of tissue culture hamster, murine or human melanoma cells into animal eyes has the advantage that the inoculation site and size of inoculum can be controlled. Disadvantages include the immune suppression necessary for tumour growth in some models as well as the fact that many of the melanoma cell lines are of cutaneous origin. Transgenic murine models have been developed using the promoter region of the tyrosinase gene to target expression of oncogenes in melanin-producing cells. Spontaneous intraocular pigmented tumours and distant metastases may occur, although many, if not all, of the intraocular tumours arise in the retinal pigment epithelium.