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M Pardo, J-CA Marshall, AL Caissie, SA Callejo, MN Burnier, G Pinard; Cyclooxygenase-2 (COX-2) Expression in Uveal Melanoma and Macrophage Cell Lines . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1136.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: COX-2, a protanglandin synthetase, plays a major role in carcinogenesis, including processes such as tumor invasion, angiogenesis, apoptosis resistance, and immunosuppression. Expression of COX-2 has been found in colon cancer and other cancers including skin and uveal melanoma. Recently, a high number of macrophages in uveal melanoma has been linked to poor prognosis of this malignancy. The aim of this study is to investigate the expression of COX-2 in five human uveal melanoma cell lines (92.1, MKT-BR, OCM-1, UW-1, and SP6.5) of different metastatic potential (MP), previously determined in an immunosuppressed rabbit model of uveal melanoma. COX-2 expression will also be investigated in a mouse macrophage cell line (ANA-1). Methods: The melanoma cells were cultured in macrophage-conditioned medium (MCM) for 12 and 24 hours. Macrophages were cultured in uveal melanoma conditioned medium (UMCM) of 92.1 (highest MP) and MKT-BR. (lowest MP) for 12 and 24 hours. All cell lines were also cultured for the same time periods without conditioned medium. Paraformaldehyde-fixed cytospins of the cell lines were immunostained using a monoclonal antibody against COX-2. Cytospins were evaluated semi-quantitatively and the stain intensity was recorded as 0, +, ++, +++. Results: With unconditioned medium all uveal melanoma cell lines were COX-2 positive (+). Under the same conditions the macrophage cell line showed a more intense (++) stain pattern. With conditioned medium we observed an increase in the amount and intensity (+++) of COX-2 expression in all the cell lines studied, with the exception of SP6.5. The effect of conditioned medium peaked at 12 hours. The most profound effect on the amount and intensity of COX-2 expression was observed in macrophages, particularly those treated with 92.1conditioned medium. Conclusion: Cultured uveal melanoma cell line secreted products stimulate COX-2 expression in macrophages. Macrophage secreted products exert a reciprocal but less intense effect on COX-2 expression in four out of five uveal melanoma cell lines. The interaction of uveal melanoma cells and macrophages may enhance the COX-2 dependent tumorigenic processes. Further experiments using a human macrophage cell line should be performed.
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