Expression of the pro-apoptotic caspase 3/CPP32 in cutaneous basal and squamous cell carcinomas.

Abstract

Apoptosis, a process of programmed cell death, plays an important role in normal and pathologic tissue homeostasis. The apoptotic cascade is triggered by caspases, a family of cystein proteases, among which caspase 3 (CPP32) seems to be the most directly related to apoptosis. Until now, few, if any, data exist on the role of CPP32 in skin tumors. We studied by immunohistochemistry, Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) the expression of CPP32 in specimens of normal human skin, basal and squamous cell carcinomas. CPP32 (both at the protein and mRNA level) was detected within epidermal and adnexal keratinocytes. CPP32 was also expressed in tumor masses of squamous cell carcinomas and more weakly in basal cell carcinomas; no correlation was found between CPP32 expression and depth of tumor invasion. CPP32 was occasionally expressed in tumor-infiltrating lymphocytes and peritumor endothelial cells. The expression of CPP32 in normal skin and in tumors arising from it suggests that this enzyme is involved in their homeostasis; its precise functional significance awaits further investigation.