Expression and heterodimer-binding activity of Ku70 and Ku80 in human non-melanoma skin cancer

Abstract

Background: Experimental data suggest that exposure to ultraviolet radiation may indirectly induce DNA double-strand breaks. Aim: To investigate the contribution of the non-homologous end-joining repair pathway in basal and squamous cell carcinomas. Methods: Levels of Ku70 and Ku80 proteins were determined by immunohistochemical analysis and Ku70–Ku80 heterodimer-binding activity by electrophoretic mobility shift assay. Matched pathological normal margins and skin from healthy people were used as controls. Results: A significant increase in Ku70 and Ku80 protein levels was found for both tumour types as compared with normal skin (pConclusions: Overall, an up regulation of the Ku70 and Ku80 protein levels seems to correlate only with tumour proliferation rate. As non-homologous end joining is an error-prone mechanism, its up regulation may ultimately increase genomic instability, contributing to tumour progression.