The expression of antimicrobial peptides is significantly altered in cutaneous squamous cell carcinoma and precursor lesions

Abstract

Antimicrobial peptides and proteins are not only effectors of the immune system but are also attributed important roles in tumour progression or tumour suppression in several malignancies such as oral squamous cell carcinoma (SCC). These reports encouraged us to systematically investigate the expression of different classes of antimicrobial peptides and proteins in tissue samples of cutaneous SCC and its precursor lesions. The protein expression of human beta-defensin (hBD)-1, -2, and -3, ribonuclease (RNase)-7 and the S100 protein psoriasin were analysed in 25 patients with actinic keratosis (AK), 30 with SCC in situ (SCCis), 23 with SCC, nine healthy skin controls and 10 healthy, chronically ultraviolet (UV)-exposed controls, by means of immunohistochemistry. Expression of hBD-1 was significantly reduced in SCC compared with UV-exposed healthy skin, AK and SCCis. RNase-7 expression was reduced gradually parallel to every step of malignant transformation, with the highest expression in healthy skin and the lowest expression in SCC. hBD-2 and psoriasin were significantly overexpressed in SCC and SCCis, compared with healthy controls. hBD-3 showed significantly more frequent expression in AK than in healthy controls, and in patients with SCCis and SCC. It is tempting to speculate that hBD-1 and RNase-7 might act as tumour suppressors while hBD-2 and psoriasin might act in the opposite way as promoters of tumour progression. Further investigations should clarify whether hBD-2 and hBD-3 could be potential targets for the development of pharmacological therapy.