Overexpression of a UV-damage recognition protein in a UV-sensitive human colon cancer cell line that features multidrug-resistant phenotype.

We have previously hypothesized that the level of UV-damage recognition protein (UVDRP) is a potential indicator of DNA-damage-mediated sensitivity or resistance of human cells to UV radiation [Chao, C.C.-K., Biochem. J. 282, 203-207, 1992]. In this study, we detected a 2-fold increase in the UVDRP binding activity in a UV-sensitive multidrug-resistant (MDR) human colon cancer cells compared to the parental SW620 cells. However, the MDR cells did not display enhanced DNA repair. The data is consistent with the conclusion that DNA excision repair is not the sole determinant of cellular sensitivity to genotoxic agents. The results also suggest that recognition of damaged DNA may be associated with generating a signal which mediates cellular sensitivity to UV radiation.