Adriamycin-induced protein and DNA damage in U937 cells.

Proteins of U937 and asPARP-U937 cells were labeled with [³H]lysine and cultured in the presence of 10⁻⁷ M adriamycin and for U937 cells with or without a 30-minute preincubation of 1 mM 3-ABA for up to 24 hours. At the time points indicated, the nuclei were isolated, lysed, and separated by nonreducing SDS–urea gel electrophoresis. DNA cross-linked protein was visualized by silver staining (A). Following ethidium bromide staining, the DNA bands were excised and the radioactivity of the DNA–cross-linked [³H]lysine-labeled proteins was quantified. Data are given as mean ± SD (n = 4) (B). Accumulation of protein-bound carbonyls (C) and appropriate proteasome activity (D) was quantified in the nuclear proteins. Data are given as mean ± SD (n = 4), respectively. DNA damage was evaluated by the comet assay (E). Data are based on 100 cells. Total fluorescence intensity, tail intensity, and tail length were calculated by the MetaMorph-software (Version 3.6a, Universal Imaging, West Chester, PA).