Figure 2.

Curcumin potentiates 5-FU-induced membrane flip-flop, caspase activation, poly (ADP-ribose) polymerase (PARP) cleavage and DNA fragmentation. (a) MDA-MB-231 cells were treated with 5-FU and/or curcumin for 16 h and stained for Annexin V-propidium iodide (PI) positivity. Annexin V-positive cells in various fields were counted, and the average was taken. The green-stained cells are those that have taken only the Annexin V-FITC stain and indicate early stages of apoptosis, and red-stained cells are those that have taken up both Annexin-FITC and PI, which indicates nuclear membrane damage, and hence represents later stages of apoptosis. Representative histograms indicates percentage of annexin positive cells. *** represent P-value ⩽0.0001. (b–e) Western blots showing curcumin-mediated enhancement of 5-FU-induced caspase activation in MDA-MB-231 cells. Whole-cell extracts were prepared after treating MDA-MB-231 cells with 5-FU and/or curcumin for 48 h and probed using anticaspase antibodies. (f) Western blot showing curcumin-mediated enhancement of 5-FU-induced PARP cleavage in MDA-MB-231cells.Whole cell extracts were prepared as described earlier and probed using anti-PARP antibody. (g) Agarose gel showing the effect of 5-FU and/or curcumin on internucleosomal DNA fragmentation in MDA-MB-231 cells. Cells were treated with 5-FU and/or curcumin for 48 h, DNA was isolated, run on an agarose gel and visualized. All experiments were repeated at least three times to confirm the reproducibility