Quercetin induced apoptosis and cell cycle arrest in MDA-MB-231 breast cancer cells.
(A) FACS analysis via Annexin V-FITC/PI staining was used to observe the induction of apoptosis in MDA-MB-231 by quercetin treatment. Representative images of the flow cytometry analysis are shown (left). Cells in the lower and upper right quadrant indicate cells with early and late apoptosis, respectively. Statistic graph presents apoptotic levels of quercetin-treated samples and untreated controls at 24 h and 48 h (right). (B) MDA-MB-231 cells were treated with quercetin for 48 h and stained with PI. Cell cycle was analyzed by FACS. M1, M2, M3 and M4 indicate sub G1, G0/G1, S and G2/M phases of cell cycle, respectively (up). The graph shows percentage of cells in each phase (down). (C) RT real-time PCR analysis for expression of FasL mRNA in MDA-MB-231 cells treated with 20 µM quercetin for 12 h, 24 h and 48 h. (D) MDA-MB-231 cells were transiently transfected with p53, p21 or GADD45-luciferase reporter for 24 h prior to treatment of 20 µM quercetin for another 24 h. Cells lysate were collected for Luciferase assay. Relative luciferase activity after normalized with Renilla luciferase reporter is shown as fold change from control. *p<0.05, **p<0.01, ***p<0.001.
