Inhibitory effect of Polo-like kinase 1 depletion on mitosis and apoptosis of gastric cancer cells

Figure 1 Effect of PLK1 depletion on members of the MPF complex. A: Western blotting showed that PLK1 levels decreased and cyclinB level increased at 48 and 72 h after RNAi targeting PLK, whereas there was almost no change in cdc2 level at 24, 48, and 72 h. B: Cdc2 activity was substantially increased at 48 and 72 h after PLK1 expression knockdown.

Figure 2 Changes in tumor cell cycle after PLK1 depletion. A: Fluorescence-activated cell sorting (FACS) analysis revealed that PLK^– MKN45 cells had an increased G₂ DNA content and were accumulated at G₂/M phase. B: Cells treated with siRNA became rounder in shape.

Figure 3 Effect of PLK1 depletion on cell proliferation.

Figure 4 Tumor cell mitosis decreases following PLK1 depletion. A: Control cells showed clear mitotic frameworks, whereas the spindles of the PLK^– depleted cells were unclear and broken when the sister chromosomes were separated. B: The five examined substages of mitosis (I-V) in both control and PLK^– depleted cells.

Figure 5 PLK1 siRNA induces MKN45 apoptosis. A: Annexin V staining and FCM revealed a higher percentage of apoptotic PLK1-depleted cells at 48 and 72 h; B: Western blotting showed reduced pro-caspase 3 levels in PLK^– cells at 48 and 72 h.