Effect of narrow-band ultraviolet B phototherapy on p63 and microRNA (miR-21 and miR-125b) expression in psoriatic epidermis.

Psoriasis is an inflammatory skin disease in which dysregulation of p63, a member of the p53 family that is crucial for skin development and maintenance, has been demonstrated. Involvement of miR-203, miR-21 and miR-125b, small non-coding RNAs implicated in the regulation of p63 or p53, has been suggested in the patho-genesis of psoriasis. To elucidate the roles of p63 and p63-related microRNAs in psoriasis and to increase our understanding of the mechanisms of narrow-band ultraviolet B (NB-UVB) phototherapy, we studied the effects of NB-UVB treatment on the expression of these molecules. Skin biopsies from 12 psoriasis patients were collected before, during and after NB-UVB therapy. Real-time PCR and immunohistochemistry showed that p63 expression was not significantly affected, whereas NB-UVB phototherapy significantly decreased expression of miR-21 (p = 0.003) and increased miR-125b levels (p = 0.003). The results indicate that the unresolved p63 abnormality in treated epidermis may play a role in maintenance of this disease.