Fig. 1
Effect of quercetin and 2-deoxy-d-glucose on cell viability and apoptosis generation. HL60 cells were either kept untreated (Cont) or treated with quercetin (Quer) and 2-deoxy-d-glucose (2-DG), alone and in combination. In the combined treatments the cells were pre-treated with Quer for 2 h, followed by addition of 2-DG for 24 h more, and with the occasional presence of the pan-caspase inhibitor z-VAD-fmk (50 μM). Drug concentrations are indicated as subheadings (Quer, μM; 2-DG, mM). When nothing is indicated, Quer was used at 20 μM and 2-DG at 5 mM. a Changes in cell viability, as evidenced by the MTT assay. Absorption values are expressed in relation to the control. b Frequency of apoptosis, represented by the sub-population of cells with sub-G1 DNA content obtained by flow cytometry. Examples of histograms showing cell cycle phases (G1, S and G2/M) and sub-G1 (Ap) are presented in c. d Frequency of early and late apoptotic cells, measured by cell surface annexin V binding and propidium iodide (PI) exclusion or uptake, respectively. e Flow cytometry histograms showing the frequency of PI-permeable cells, indicating plasma membrane disruption. The bar charts in (a–b) represent the mean ± S.D. of at least three determinations, measured by duplicate. The histograms in (d, e) are representative of one out of three determinations with similar results. Symbols mean: (*) significant differences between single treatments; (#) significant differences between the combined treatment and the sum of values in the corresponding individual treatments (e.g., co-incubation with 20 μM Quer and 5 mM 2-DG, in relation to the sum of 20 μM Quer alone plus 5 mM 2-DG alone) (n.s. non-significant). To better discern differences, in this case the sum of values in individual treatments is indicated by a thick black bar within the bar corresponding to the combined treatment. Single symbol, p < 0.05; double symbol, p < 0.01; triple symbol, p < 0.001