Immunohistochemical and prognostic analysis of apoptosis and proliferation in uveal melanoma.

Neoplasia can be defined as deregulated tissue homeostasis caused by an imbalance between proliferation and apoptosis. Many genes are involved in the maintenance of tissue homeostasis, eg, the c-myc oncoprotein, which is an important regulator of cell proliferation and Bcl-2 protein, which is involved in the regulation of apoptosis. We studied retrospectively indices of proliferation, such as mitotic count and the Mib-1 index, on 51 uveal melanomas and compared their prognostic significance with established indicators of prognosis such as cell type and tumor size. Along the same line we investigated the expression of the regulating proteins c-myc and Bcl-2. Of all parameters tested, the largest tumor diameter and mitotic count were most strongly associated with tumor-related death (P < 0.001 and P = 0.005, respectively). In addition, cell type, the presence of epithelioid cells, the Mib-1 index, and the percentage of cytoplasmic c-myc-positive cells were significant predictive factors. Multivariate analysis showed that the Mib-1 index, largest tumor diameter, and the percentage of cytoplasmic c-myc-positive cells were independent prognostic parameters. Bcl-2 expression did not correlate with clinical outcome. The Mib-1 index correlated with the presence of epithelioid cells (P < 0.03) and the presence of apoptotic bodies (P < 0.001) and c-myc. A strong inverse relationship was found between (nuclear and cytoplasmic) c-myc and Bcl-2 (P < 0.00004 and P < 0.006, respectively), suggesting that Bcl-2 cooperates with c-myc to immortalize uveal melanoma cells.