Expression of cyclin D1 and p16 in psoriasis before and after phototherapy

P>Background. Psoriasis vulgaris (PV) is characterized by keratinocyte hyper-proliferation. Altered expression of cell-cycle regulatory genes involved in the cyclin D1/p16 INK4-pRb pathway may contribute to this epidermal hyperproliferation. Aim. To assess the expression of cyclinD1 and p16 in psoriasis, and to evaluate the effect of phototherapy on their expression. Methods. The study population comprised 25 patients with PV and 10 healthy controls. Patients were treated with 24 sessions of either narrowband ultraviolet (UV) B or psoralen UVA. Skin biopsies were taken from the affected skin of each patient before and after treatment, and from the healthy controls, to examine cyclin D1 and p16 expression. Results. Before phototherapy, the mean value of cyclin D1 concentration in patients was significantly greater than that in controls and the mean value of p16 concentration in patients was significantly lower than that in controls. Following treatment, we detected a significant decrease in cyclin D1 and a significant increase in p16. Conclusion. Cyclin D1 upregulation and p16 downregulation may play a role in the pathogenesis of psoriasis. Normalization of the levels of both parameters may be a mechanism by which phototherapy induces remission in psoriasis.