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N. Goldenberg-Cohen, O. Dratviman-Storobinsky, N. Binkovsky, S. Frenkel, Y. Cohen, J. Pe'er; The Role of RASSF1A in Uveal Melanoma. Invest. Ophthalmol. Vis. Sci. 2010;51(13):857.
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© ARVO (1962-2015); The Authors (2016-present)
Uveal melanoma (UM) is the most common intraocular tumor, with mortality from liver metastasis in up to 50% of cases. It is not yet possible to predict those that will die from metastasis. RASSF1A, a tumor suppressor gene, plays a role in the tumorigenesis of UM. Inactivation of RASSF1A by epigenetic methylation may affect UM patients’ prognosis and outcome. To investigate the role of RASSF1A in the development of UM and risk of liver metastasis, we examined a UM cell line proliferation after injection to mice, following exogenous activation of RASFF1A.
RASSF1A was found to be inactivated in the UM paternal cell line. The cells were transfected with exogenous RASSF1A-containing plasmid or empty plasmid. The transfected cells were injected subcutaneously or intraocularly, into male 5-6 week-old athymic BALB/c nude mice. Three experimental groups received the following cells: (1) the parental non-transfected UM cell line; (2) the empty pcDNA3.1 vector-transfected cells from the same parental origin; (3) the RASSF1A-pcDNA3.1-transfected cells from the same parental origin.The tumors were measured with calipers twice a week. Tumor volume was calculated and the mice were sacrificed once the tumors reached 1500 mm3 or 45 days. Tumor tissues, eyes, and livers were analysed histologically by hematoxylen-eosin staining. The expression of the RASSF1A gene was examined in the tumor samples using Real-time-PCR.
Cell lines transfected with exogeneous expressing RASSF1A plasmid did not cause intraocular tumors, and the subcutaneous tumors were delayed and smaller, as compared to paternal UM cell-lines and cells transfected with empty vector. Regardless of tumor size, none of the groups developed liver metastasis.
In the presence of activated RASFF1A, the cells demonstrated reduced tumorigenicity potential. Subcutaneous tumors were smaller and no intraocular tumor was detected. The lack of liver metastasis in all groups might be due to the short period of the experiments (45 days). We therefore conclude that RASSF1A has an important role in the development of UM. Its activation may be used for developing future treatments.
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