Protective effect of TiO2 particles on UV light induced pyrimidine dimer formation

UV light irradiation is known to induce DNA damage, e.g. pyrimidine dimers, which is expected to introduce genetic damage in tissues and cells. Here, we have studied the effects of TiO2 particles on UV-induced pyrimidine dime r formation. Pyrimidine photoproducts (6-4 type) and cyclobutane-type pyrimidine dimers were detected by using monoclonal antibodies for these dimers in both norma l human cells (TIG-1) and human cancer cells (T24) after UVC light irradiat ion. Application of TiO2 particles to cell surfaces reduced the extent of U VC-induced dimer formation. On mouse skin, UVC introduced both types of pyr imidine dimers, and the presence of TiO2 particles on the surface of mouse skin also reduced the UVC-induced pyrimidine dimer formation. UVA light irradiation, on the other hand, did not introduce dimer formation in either cultured cells or in mouse skin tissues, and TiO2 did not have a significant effect on UVA irradiation. The presence of TiO2 did not influe nce the repair of the UVC-induced pyrimidine dimers. These effects confirm the usefulness of TiO2 as a protective agent against UV-induced DNA damage in cells and tissues. (C) 2001 Elsevier Science B.V. All rights reserved.