Sebastian Di Cesare

Molecular Pathways Mediating Liver Metastasis in Patients with Uveal Melanoma

Uveal melanoma arises from melanocytes located in the uveal tract of the eye and is the most common primary intraocular tumor in adults. Metastatic liver disease is the overwhelming cause of death in uveal melanoma patients, with almost 50% of patients developing liver metastases up to 15 years after diagnosis. Most of these patients do not present with any evidence of overt metastasis at the time of initial diagnosis although it is assumed that they have undetectable micrometastases. Currently, there are no therapeutic modalities to prevent or efficiently treat the metastatic disease in uveal melanoma patients. Recent discoveries have shed light on the molecular pathways that may contribute to the progression of liver metastasis. The aim of this review is to describe new insights into the genetic and molecular pathways that may play a role in the development of liver metastases in uveal melanoma patients.

Expression of cyclooxygenase-2 in choroidal neovascular membranes from age-related macular degeneration patients.

Purpose: The objective of this study was to investigate the expression of cyclooxygenase (COX)-2 in human choroidal neovascular membranes. Methods: Paraffin-embedded sections of choroidal neovascular membranes excised from 16 patients with wet age-related macular degeneration were used for this study. Sections were subjected to immunohistochemistry using a monoclonal mouse antihuman COX-2 antibody. Staining was classified as either negative or positive in retinal pigment epithelial cells, vascular endothelial cells, and fibroblasts. Serial sections were stained for vimentin expression to confirm tissue antigenicity. Results: Eleven of 16 (69%) choroidal neovascular membranes stained positive for COX-2 in retinal pigment epithelial cells, with 6 (38%) of these also expressing COX-2 in vascular endothelial cells and 6 (38%) in fibroblasts. None of the sections that were negative for COX-2 in the retinal pigment epithelial cells showed COX-2 expression in the other cell types assessed. There was a statistically significant difference (P = 0.0097) in the mean ages between the COX-2 positive group (65.6 years) and COX-2 negative group (76.8 years) as determined by a two-tailed, unpaired Student’s t-test. Conclusion: The expression of COX-2 in human choroidal neovascular membranes suggests a possible role for this modulator in age-related macular degeneration pathogenesis. The age-dependent expression observed is novel and warrants further investigation.

Lysyl oxidase expression and inhibition in uveal melanoma.

Lysyl oxidase is a marker of poor prognosis in several malignancies and is hypothesized to promote a migratory phenotype in hypoxic breast carcinomas. This study aims to characterize the expression of the lysyl oxidase and lysyl oxidase-like proteins in human uveal melanoma cell lines and archival choroidal melanomas using immunohistochemistry. The transcriptional control of lysyl oxidase will also be investigated under simulated hypoxic conditions using cobalt chloride. Lastly, changes in cellular proliferation and invasion will be assessed after the treatment of cell lines with β-aminopropionitrile, a lysyl oxidase catalytic inhibitor. Retrospective analysis of lysyl oxidase expression in primary human uveal melanoma showed 82% (27 of 33) of tumors being stained positive. High lysyl oxidase expression correlated with the aggressive epithelioid cell type and was associated with shorter metastasis-free survival. Simulated hypoxia resulted in a significant increase in lysyl oxidase mRNA expression. Inhibiting lysyl oxidases catalytic activity significantly reduced cellular invasion but had no effect on cell proliferation. Our study is the first to show lysyl oxidase expression in primary choroidal melanomas. This protein may represent a potential therapeutic target that warrants further study in this malignancy.

The effect of blue light exposure in an ocular melanoma animal model

BackgroundUveal melanoma (UM) cell lines, when exposed to blue light in vitro, show a significant increase in proliferation. In order to determine if similar effects could be seen in vivo, we investigated the effect of blue light exposure in a xenograft animal model of UM.MethodsTwenty New Zealand albino rabbits were injected with 1.0 × 106 human UM cells (92.1) in the suprachoroidal space of the right eye. Animals were equally divided into two groups; the experimental group was exposed to blue light, while the control group was protected from blue light exposure. The eyes were enucleated after sacrifice and the proliferation rates of the re-cultured tumor cells were assessed using a Sulforhodamine-B assay. Cells were re-cultured for 1 passage only in order to maintain any in vivo cellular changes. Furthermore, Proliferating Cell Nuclear Antigen (PCNA) protein expression was used to ascertain differences in cellular proliferation between both groups in formalin-fixed, paraffin-embedded eyes (FFPE).ResultsBlue light exposure led to a statistically significant increase in proliferation for cell lines derived from intraocular tumors (p < 0.01). PCNA expression was significantly higher in the FFPE blue light treated group when compared to controls (p = 0.0096).ConclusionThere is an increasing amount of data suggesting that blue light exposure may influence the progression of UM. Our results support this notion and warrant further studies to evaluate the ability of blue light filtering lenses to slow disease progression in UM patients.

In vitro characterization and inhibition of the CXCR4/CXCL12 chemokine axis in human uveal melanoma cell lines

PurposeThe CXCR4/CXCL12 chemokine axis may play a critical role in guiding CXCR4+ circulating malignant cells to organ specific locations that actively secrete its ligand CXCL12 (SDF-1) such as bone, brain, liver, and lungs. We sought to characterize the presence of the CXCR4/CXCL12 axis in five uveal melanoma (UM) cell lines in vitro. The ability of TN14003, a synthetic peptide inhibitor that targets the CXCR4 receptor complex, to inhibit this axis was also assessed.MethodsImmunocytochemistry was performed against CXCR4 to confirm expression of this chemokine receptor in all five UM cell lines. Flow cytometry was preformed to evaluate CXCR4 cell surface expression on all five UM cell lines. A proliferation assay was also used to test effects TN14003 would have on cellular proliferation. Inhibition of cellular migration by specifically inhibiting the CXCR4/CXCL12 axis with TN14003 was also investigated. The binding efficacy of TN14003 to the CXCR4 receptor was assessed through flow cytometric methods.ResultsThe CXCR4 receptor was present on all five UM cell lines. All five cell lines expressed different relative levels of surface CXCR4. TN14003 did not affect the proliferation of the five cell lines (p > 0.05). All cell lines migrated towards the chemokine CXCL12 at a level greater than the negative control (p < 0.05). All 5 cell lines pre-incubated with TN14003 prevented cellular migration towards chemokine CXCL12 (p < 0.01). TN14003 preferentially binds CXCR4 to native ligand CXCL12.ConclusionInterfering with the CXCR4/CXCL12 axis, using TN14003 was shown to effectively down regulate UM cell migration in vitro. Knowing that UM expresses the CXCR4 receptor, these CXCR4+ cells may be less likely to colonize distant organs that secrete the CXCL12 ligand, if treated with an inhibitor that binds CXCR4. Further studies should be pursued in order to test TN14003 efficacy in vivo.

Immune Expression and Inhibition of Heat Shock Protein 90 in Uveal Melanoma

Purpose: To examine the immunohistochemical profile of heat shock protein 90 (Hsp90) in uveal melanoma and the cytotoxicity of an Hsp90 inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), in uveal melanoma cell lines. Experimental Design: Hsp90 expression was determined by immunohistochemistry in 44 paraffin-embedded sections of primary human uveal melanoma and in five uveal melanoma cell lines (92.1, OCM-1, MKT-BR, SP6.5, and UW-1). Sulforhodamine B–based proliferation assay was used to compare uveal melanoma cell growth with a range of concentrations of 17-AAG. Changes in cell migration, invasion, cell cycle fractions, and apoptotic activity were also evaluated. Expression of intracellular proteins was determined by Western blot analysis after 17-AAG exposure. Results: Immunohistochemical expression of Hsp90 was identified in 68% of the paraffin-embedded sections and significantly associated with largest tumor dimension (P = 0.03). 17-AAG significantly reduced the proliferation rates of uveal melanoma cell lines, with concentrations of 100 to 0.1 μmol/L. 17-AAG also significantly reduced the migratory and invasive capabilities of uveal melanoma cell lines. Cell cycle analysis showed that 17-AAG induced accumulations of cells in G1. Caspase-3 protease activity analysis, a marker for apoptosis, showed a significant increase after drug exposure. The cytotoxic effect of 17-AAG was associated with decreased levels of phosphorylated Akt and cyclin-dependent kinase 4. Conclusions: The immunohistochemical expression of Hsp90 in uveal melanoma indicates worse prognosis. To the best of our knowledge, this is the first report showing the inhibitory effect on uveal melanoma cells using 17-AAG to target Hsp90. Therefore, Hsp90 may be used as a potential target for treatment of patients with uveal melanoma.

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.

Eyelid and conjunctival paracoccidioidomycosis simulating carcinoma

Paracoccidioidomycosis (PCM) is the most prevalent systemic mycosis in immunocompetent individuals in Brazil. Ocular infection by PCM is rare; however, when infection does occur, the most common ocular sites involved are eyelid and conjunctiva. A 68-year-old white male presented with a 2-month history of a painless, ulcerated, infiltrative and diffuse whitish lesion located on the right inferior eyelid. A clinical diagnosis of malignant tumor, possibly squamous cell carcinoma, was made. The histopathologic examination showed a hyperplastic epithelium with inflammatory infiltrate of lymphocytes, plasma cells, neutrophils and histiocytes. Large numbers of giant cells were also present. Periodic acid Schiff and Grocott (silver methenamine) stains showed several large round structures with peripheral lateral small budding cells that resembled a “ship’s wheel”. No multinucleated fungi were seen. The fungi varied in size and small forms were round and single fungal structures. A diagnosis of paracoccidioidomycosis was made PCM eyelid infection is rare and can simulate carcinoma both clinically and histopathologically.

Use of CD25 as an immunohistochemical marker for acquired ocular toxoplasmosis.

PURPOSE Toxoplasmosis is the most common cause of posterior infectious uveitis worldwide. It is often impossible to determine its congenital or acquired nature. Interleukin-2 (IL-2) in peripheral blood has been described as a possible marker for acquired toxoplasmosis. The purpose of this study is to evaluate the histopathological characteristics of ocular toxoplasmosis cases using CD25 as a marker for the expression of interleukin-2. METHODS Ten formalin-fixed, paraffin-embedded enucleated globes from ten immunocompetent patients with clinical diagnosis of toxoplasmosis were evaluated. Four patients had the acquired form of ocular toxoplasmosis (positive IgM) while six were IgM negative and IgG positive for toxoplasmosis. Histopathological slides were reviewed for the extension of the retinal necrosis, number of toxo cysts, the granulomatous inflammatory reaction, the presence of T and B cells within the choroid and the IL-2 expression. Immunohistochemistry using monoclonal antibodies was performed to observe the expression of CD4, CD8, CD20, CD25, and CD68. RESULTS The histopathological evaluation disclosed no differences between acquired and the other ocular toxoplasmosis cases regarding the characteristics studied. However, CD25 showed a higher expression of IL-2 on the 4 acquired cases of ocular toxoplasmosis compared to the remainders. CONCLUSIONS To the best of our knowledge, this is the first report showing that the use of CD25 as a marker for interleukin-2 could differentiate acquired ocular toxoplasmosis.

Expression of EpCAM in uveal melanoma

BackgroundUveal melanoma (UM) is the most common primary intraocular malignant tumor in adults, and nearly 40% of UM will develop metastasis that will ultimately lead to death. The Epithelial Cell Adhesion Molecule (EpCAM) is a type I transmembrane glycoprotein expressed by carcinomas of head and neck, ovary, colon, breast, kidney and lung. Recently, antibodies against EpCAM such as Edrecolomab and Catumaxomab were developed, and clinical trials with these antibodies have been used in several types of neoplasia. We studied the expression of EpCAM in UM.Methods25 enucleated formalin-fixed, paraffin-embedded UM specimens were immunostained for EpCAM. Histopathological analysis of the specimens with regards to prognostic factors such as cell type, largest (linear) tumor dimension, number of mitotic figures, scleral invasion and tumor infiltrating lymphocytes were done.ResultsNone of them was positive for this EpCAM.ConclusionIn our report, UM did not express EpCAM. Therefore, it is not a helpful immunohistochemical marker to predict the behavior of UM. Further studies are needed to verify if EpCAM could also be related with prognosis and treatment of UM.