Abstract:The renin-angiotensin system (RAS) is known mainly as a regulator of cardiovascular homeostasis. However, it has also been shown to mediate processes such as proliferation, apoptosis, angiogenesis, and carcinogenesis. Nonmelanoma skin cancers (NMSC) -including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) -are among the most common cancers. The aim of the present study was to determine the immunohistochemical expression of angiotensin-converting enzyme (ACE), angiotensin-converting enzyme 2 (ACE2), and Ki-67 antigen in archival samples of normal skin, actinic keratosis, and malignant skin lesions. Cytoplasmic-nuclear ACE immunoreactivity was observed in 99% of examined cases of both normal skin and cancers. Significantly higher ACE immunoreactivity occurred in normal skin, as compared with BCC and SCC (p < 0.01, p < 0.0001, respectively). Additionally, ACE immunoreactivity was also significantly higher in BCC, compared with SCC (p < 0.05). ACE2 immunoreactivity was noted in basal epidermal layers and in sebaceous gland cells in normal skin, though not in NMSC. These novel observations suggest that ACE and skin RAS may be involved in the pathogenesis of malignant skin lesions.