PDK4 mediates the response of colon cancer cells to 5-FU-induced apoptosis.
A, knockdown of PDK4 expression by shRNAs was confirmed in HCT116 and CBS cells by Western blotting. Ctrl, control. B, PDK4 knockdown and control cells were treated with different concentrations of 5-FU for 72 h. DNA fragmentation assays were performed. C, Western blotting analyses of cleaved PARP (C-PARP), Bcl-2, and survivin were performed in PDK4 knockdown and control cells after 2.5 μg/ml (for HCT1116) or 5.0 μg/ml (for CBS) 5-FU treatment for 72 h. D, expression of PDK1, PDK2, and PDK3 was knocked down individually by their respective siRNA pools in HCT116 cells (top panel). The knockdown and control cells were treated with different concentrations of 5-FU for 72 h. DNA fragmentation assays were performed (bottom panel). E, PDK4 was overexpressed in HCT116 cells (left panel). Expression of Bcl-2 and survivin was determined in those cells (center panel). Cells were treated with different concentrations of 5-FU for 72 h. DNA fragmentation assays were performed (right). Vec, vector. The data are presented as the mean ± S.D. of triplicate experiments. **, p < 0.01; ***, p < 0.001.