EXPRESSION OF ANTI-APOPTOTIC PROTEIN BCL-2 IN CUTANEOUS BASAL CELL CARCINOMA

Abstract

Purpose: Overexpression of antiapoptotic B-cell lymphoma-2 (Bcl-2) protein is one of the major contributors to oncogenesis and high levels have been identified in a variety of tumour types. We investigated an immunohistochemicalexpression of Bcl-2 protein in cutaneous basal cell carcinomas (BCCs) to elucidate whether there are differences in the expression pattern related to tumour growth phenotype.Materials and Methods: The study group consisted of 45 cutaneous BCCs, which were categorised into the nonaggressive (NA-BCCs; 31 cases) and aggressive histologic variants (A-BCCs; 14 cases).Results: There were 3 tumours (6.6%) with negative staining and 42 tumours (93.4%) with positive staining for Bcl-2 protein, 10 of which (23.8%) displayed low and remaining 32 cases (76.2%) exhibited high expression. All three “Bcl-2 negative” BCCs showed aggressive-growth features (infiltrative subtypes). When Bcl-2 values were evaluated as negative/low versus high expression, there was significantly lower Bcl-2 protein expression in the A-BCCs comparedto the NA-BCCs. Even an intensity of immunostaining showed a tendency of being weaker in the A-BCCs. In spite of that, three infiltrative BCCs showed a diffuse strong immunoreactivity.Conclusion: An immunohistochemical positivity of Bcl-2 protein in the neoplastic cells of cutaneous BCC was nearly constant feature, and its decreased staining was associated with an infiltrative growth pattern. It suggests that a lowBcl-2 protein expression in tumor tissue might be considered an unfavorable prognostic indicator.Key words: Basal cell carcinoma, B-cell lymphoma-2 protein, biological behavior