Fig. 1.

Validation of the selective inhibitory effect of resveratrol toward tetraploid cells. (A–D) Multiple diploid and tetraploid clones from human colon carcinoma HCT116 cells (framed in green and red, respectively) were treated with the indicated concentrations of resveratrol for 48 h before the evaluation of the cell-death–associated parameters either by cytofluorometry upon costaining with the vital dye iodure propidium (PI) and the mitochondrial membrane potential (Δψ_m)-sensing dye DiOC₆(3) (A and B) or by fluorescence microcopy upon coimmunostaining with antibodies directed against cytochrome c (Cyt c) and activated caspase 3 (Caspase-3a) (C and D). A illustrates representative dot plots (numbers refer to the percentage of cells found in each quadrants), whereas B shows quantitative data (mean ± SEM; n = 5) from experiments performed on eight different diploid and seven tetraploid clones. Representative pictures and the quantification of cells displaying Cyt c release, caspase-3 activation (Caspase-3a⁺), and pyknotic nuclei (as determined by nuclear counterstaining with Hoechst 33342) are reported in C and D, respectively (mean ± SEM; n = 500 cells). In B, the fraction of dying (DiOC₆(3)^low PI⁻) and dead cells (PI⁺) is represented by white and black columns, respectively, and cisplatin (CDDP) was used as a negative control. **P < 0.01; ***P < 0.001 (Student t test), compared with the equally treated diploid cells. See also Figs. S2 and S3.