An immunohistochemical analysis of nm23 gene product expression in uveal melanoma

Uveal melanoma is characterized by an unpredictable clinical course, during which metastatic disease may occur after a prolonged and, at present, undefinable disease-free interval. Because of its relative rarity and the dispersion of cases, the possible genetic alterations implicated in the invasive and metastatic behaviour of this ocular neoplasm have not yet been characterized. The aim of this immunohistochemical retrospective study was to assess the expression of nm23 gene product, proposed to be a metastasis-suppressor gene, in uveal melanoma and to analyse its prognostic significance in relation to the various conventional histopathological parameters, currently considered the major prognostic indicators in this intra-ocular neoplasm. We analysed formalin-fixed paraffin-embedded samples excised from 33 patients with uveal melanoma. Of these, 22 (67%) were positive for monoclonal antibody nm23. This nm23 positivity was inversely associated with scleral invasion level (P = 0.001) and largest tumour diameter (P = 0.02), which represent the two most significant prognostic factors for metastasis. On the other hand, there was no correlation between nm23 expression and other prognostic markers such as cell type, intraocular location or clinical characteristics. These results may suggest a close relationship between nm23 gene expression and metastatic potential of uveal melanomas. In addition, analysis of nm23 gene expression on bioptic tissue may represent an extreme useful prognostic tool for metastatic progression of uveal melanomas.