Fig. 3
BTZ resistance protects CMY cells from S phase arrest by Ara-C. CMY and CMY-BR100 cell lines were treated with increasing concentrations of Ara-C, from 1 nM to 150 μM and viability plotted as percent of control (y-axis) against Log10 nM Ara-C (x-axis). After 72 h almost all the CMY parent cells died at high Ara-C doses, but the viability of CMY-BR cells remained at 50% at the same concentration and time points. After 4 days of exposure to high doses of Ara-C, the CMY-BR cells still maintained 25% viability (a). Cell cycle phase distribution of CMY and CMY-BR cell lines after treatment with 1, 10 and 100 μM Ara-C at 72 h were analyzed. CMY cells demonstrated an S-phase arrest at 1 and 10 μM Ara-C, with cell death at 100 μM. However, the CMY-BR cells showed an accumulation in the G1 phase, no S-phase arrest regardless of the Ara-C concentration used. (b). Cell cycle was analyzed using propidium iodide (PI) staining and flow cytometry. The plots show PI staining at the x-axis and cell counts at the y-axis. The graphs were prepared using ModFit LT™ software (Verity Software House). Nd: not detected