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A.P. Figueiredo, P.C. Ferreira, G.S. Lima, F.R. Lopes, G. Gubert, P. Trevisol; RhoC Expression in Primary Uveal Melanomas . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2242.
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The Rho proteins are Ras–related guanosine triphosphatases (GTPases) that function in cytoskeletal reorganization, cell migration, and stress fiber and focal adhesion formation. Overexpression of RhoC enhances the ability of skin melanoma cells to metastasize. In this study, the purpose was to investigate the expression of RhoC in human ocular melanoma and correlate with histopathologic prognostic factors.
Twenty standard paraffin sections of primary uveal melanoma tissue specimens were retrieved, prepared and blocked for immunohistochemistry to detect the expression of RhoC. Slides were also reviewed to determine known prognostic factors such as cell type (spindle, mixed, and epithelioid), tumor infiltrating lymphocytes, closed loops and the expression of RhoC was related to these factors. Cases were divided into 2 groups according to RhoC tumor cell expression: negative or positive if at least 20 cells displayed distinct immunostaining.
Of the 20 cases investigated, 15 tumors (75%) were considered positive for RhoC in malignant cells. The most intense and diffuse RhoC staining was observed in a highly aggressive tumor ( 20 mitotic figures per HPF), and in general, appears to be concentrated in proliferating margins of the tumors. The expression of this molecule in the tumor strongly correlated with epithelioid (80%, 4 of 5) and mixed cell type (65%, 9 of 14), lymphocytic infiltration (65%, 13 of 20), and vascular loops presence (65%, 13 of 20).
Uveal melanoma cells do express RhoC. Our findings suggest that RhoC expression has potential to be linked to local aggressive behavior in human uveal melanoma cells. These results provide compelling evidence to further explore whether RhoC inhibitors may be clinically useful in patients with ocular melanoma.
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