Psoriasis patients with basal cell carcinoma have more repair-mediated DNAstrand-breaks after UVC damage in lymphocytes than psoriasis patients without basal cell carcinoma

We have investigated the formation of strand-breaks following UVC irradiati on in lymphocytes from psoriasis patients with or without basal cell carcin oma (BCC). Isolated lymphocytes were irradiated with UVC light at a dose of 3.6 J/m(2), and the level of DNA strand-breaks were measured 25 min after the irradiation by the alkaline comet assay. The generation of strand-break s following WC irradiation indicates DNA-repair-mediated incisions, as UVC light does not generate strand-breaks per se. We found that psoriasis patie nts with BCC had more DNA-repair incisions than non-cancer patients. The in cision level correlated to two polymorphisms of the XPD gene. At present, i t is not dear if the association is a primary effect that is related to dif ferences of the XPD protein. Genes encoding for other repair proteins, name ly XRCC1, ERCC1, and LIG1 are located close to the XPD gene, and it is poss ible that the association is due to a cosegregation with a polymorphism in one of these genes. (C) 2000 Elsevier Science Ireland Ltd. All rights reser ved.