FL118 selectively and differentially modulates the expression of IAP and Bcl-2 family proteins.

<p>Subconfluent cells were treated with and without FL118 at the concentration and time points as shown (<b>a</b>–<b>c</b>). Cells were then lysed and analyzed by western blot. Representative results are shown. <b>a.</b> A time course for FL118-mediated inhibition of survivin expression in 2008 ovarian cancer cells. <b>b.</b> Differential modulation of the expression of antiapoptotic and proapoptotic proteins by FL118 in PC-3 prostate cancer cells. Quantification as %Control: 100, 7, 5 for survivin; 100, 9, 12 for Mcl-1; 100, 88, 77 for Bcl-2; 100, 54, 49 for Bcl-XL; 1, 100, 43 for Bax; 1, 18, 74 for Bim. <b>c.</b> Downregulation of survivin, XIAP, cIAP2 and Mcl-1 by FL118 in HCT-8 colon cancer cells. The “*” in the survivin panel indicates the potential expression of the proapoptotic protein survivin-2B after FL118 treatment. Quantification as %Control: 100, 11, 7 for survivin (of note, the asterisk-marked band excluded); 100, 9, 8 for XIAP; 100, 22, 12 for cIAP2; and 100, 13, 6 for Mcl-1. <b>d.</b> Genetic silencing of survivin does not affect the expression of other FL118 downstream targets. HCT-8 colon cancer cells were infected with lentiviral survivin-shRNA for 48 hours, followed by western blot analysis of the expression of FL118 downstream targets. Quantification as %Control: 100, 13 for survivin; 100, 96 for XIAP; 100, 98 for cIAP2; and 100, 136 for Mcl-1. Of note, the survivin level without mock lentiviral infection is similar to the mock control lentiviral infected cells (not shown). Actin expression shown in <b>a–d</b> is internal controls. <b>e.</b> FL118 inhibits Mcl-1 promoter-driven luciferase activity. Subconfluent HCT-8 colon cancer cells were transiently transfected with pGL2-Mcl-1. The transfected cells were treated with or without FL118 for 24 hours 16 hours post transfection. Each bar is the mean ± SD derived from three independent assays.