bcl-2 protein expression in cutaneous malignant melanoma and benign melanocytic nevi.

bcl-2 is a proto-oncogene belonging to a new category of oncogenes that are not involved in the mechanisms of cell proliferation but instead influence tissue homeostasis regulating cell death. The gene encodes for a protein that preserves cells from death by apoptosis, allowing them to survive in G(o) phase even in the absence of essential growth factors. The expression of bcl-2 protein has been observed in most follicular lymphomas and in approximately 25% of high-grade non-Hodgkin's lymphomas, as well as in solid tumors such as carcinomas of the lung, prostate, and nasopharynx. In this study, we analyzed bcl-2 protein expression in cutaneous malignant melanoma (MM) (29 cases) and benign melanocytic nevi (BMN) (35 cases) using a high specific anti-bcl-2 monoclonal antibody with a standard three-step immunoperoxidase technique on formalin-fixed, paraffin-embedded tissue sections. High levels of bcl-2 protein were observed in 27 of 29 MM (93.1%) and 33 of 35 BMN (94.3%). Our results indicate that bcl-2 protein expression is a common finding in cutaneous melanocytic lesions regardless of their biologic behavior. Expression of the protein in the great majority of MM seems to exclude a prognostic significance of bcl-2 in MM of the skin.