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

Apoptosis, a process of programmed cell death, plays an important role in n ormal 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 ally , data exist on the role of CPP32 in skin tumors, We studied by immunohisto chemistry, 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) wa s detected within epidermal and adnexal keratinocytes. CPP32 was also expre ssed in tumor masses of squamous cell carcinomas and more weakly in basal c ell 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 nor mal skin and in tumors arising from it suggests that this enzyme is involve d in their homeostasis; its precise functional significance awaits further investigation.