bcl-2 expression in primary malignancies of the skin

Basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and malignant melanoma (MM) are the three most common malignant neoplasms that arise in the skin. Deregulation of oncogene function not infrequently leads to an increased rate of cellular proliferation. However, the expansion of malignant cells can also occur if programmed cell death is inhibited. The oncogene bcl-2 participates in the regulation of apoptosis (programmed cell death). In view of this, we determined the presence and possible role of bcl-2 in primary cutaneous malignancies. Routine paraffin sections of formalin-fixed BCCs, SCCs, MMs (primary and metastatic), actinic keratoses, and SCCs in situ were labeled with anti-bcl-2 monoclonal antibody using a biotin-avidin-immunoperoxidase procedure.

Twenty-three BCCs were examined and all expressed cytoplasmic bcl-2. Two of 20 SCCs were positive. One of these had patchy, diffuse staining, and the other stained in only small foci. None of eight SCCs in situ and none of eight actinic keratoses expressed bcl-2. Sixteen of 18 MMs expressed bcl-2.

The bcl-2 gene product has been found to inhibit apoptosis. Our preliminary results suggest that the expression of bcl-2 is present quite consistently in BCCs and MMs, but not in SCCs or precursor lesions. The expression (or lack thereof) of bcl-2 may reflect the difference in the regulation of cell turnover between these tumors, or histogenetic differences.