EXPRESSION OF THE APOPTOSIS-SUPPRESSING PROTEIN BCL-2 IN NONMELANOMA SKIN-CANCER

Basal cell carcinoma (BCC) is typically a slow-growing malignant tumou r, composed of cells similar to those in the basal area of the epiderm is. We investigated the expression of bcl-2 (B-cell leukaemia/lymphoma -2) in BCC, and also in squamous cell carcinoma (SCC) of the skin. The proto-oncogene bcl-2 encodes a protein which inhibits programmed cell death (apoptosis). The protein is expressed in basal cells in normal human epithelium, but not in the suprabasal cell layers. Immunohistoch emical localization using a monoclonal anti-Bcl-2 antibody revealed bc l-2 expression in all the BCCs (15 patients). SCCs did not express bcl -2 (five patients). The positive Bcl-2 staining of BCC tumour cells su pports the hypothesis that BCCs originate from the basal layer of the epidermis. The bcl-2 expression of BCC tumour cells also suggests a ne oplastic transformation caused by extended cell survival rather than i ncreased cell proliferation. This type of neoplastic growth is possibl y associated with less aggressive tumour behaviour.