Abstract

Corticotropin-releasing hormone receptor-1 (CRH-R1) is expressed in human mast cells, but its role in skin diseases is unknown. By using a sequential double-staining technique, the mast cell expression of CRH-R1 was investigated in biopsies from lesional and non-lesional skin samples of patients with actinic keratosis (AK), basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and psoriasis. Dermal tryptase⁺ mast cells expressed CRH-R1 immunoreactivity in the non-lesional skin in all patient groups. The CRH-R1 expression was significantly increased in the lesional skin of AK (p = 0.03) and psoriasis (p = 0.02), non-significantly in BCC (p = 0.129), but not increased in SCC. To investigate the regulation of CRH-R1, the LAD2 mast cell line was irradiated with UVB or stimulated with CRH or 1,25-dihydroxyvitamin D₃ [1,25-(OH)₂D₃]. Consequently, UVB at 90 mJ/cm² (p = 0.041) and 120 mJ/cm² (p = 0.039) decreased CRH-R1 expression. Instead, CRH at 100 and 1000 nM increased CRH-R1 immunostaining, but did not affect the proliferative response. The treatment with 10 and 100 nM 1,25-(OH)₂D₃ led to a noticeable increase in CRH-R1 staining. After irradiating with UVB, the concentration of CRH increased in the conditioned medium, but not in sonicated LAD2 mast cells. In conclusion, the lack of sufficient levels of CRH-R1 in mast cells may be related to diminished antitumoural response in SCC and possibly in BCC.