A549 clonal cell population sensitivity to FK866 (5 nM) before and after IDO induction.

Proliferation of each of 5 individual A549 cell clonal populations before (Panel A) and after (Panel B) IDO induction with IFNγ. A549 clonal cell populations were cultured with or without IFNγ (25 ng/ml) for 48 h. Medium was then replaced with fresh growth medium containing FK866 (5 nM) and cells were allowed to proliferate for 72 h. Cells were then trypsinized and live cells were enumerated. White bars: A549 clones transfected with scrambled, non-targeting control shRNA. Gray bars: A549 cells transfected with anti-IDO shRNA. Results are normalized to control cells not treated with FK866, without (panel A) or with (panel B) IFNγ treatment. Each bar represents the mean of 3 values (n = 3) ± SD, (*, p≤0.05). Panel C: A549 clonal resistance to FK866 before and after IFNγ-mediated IDO induction. Pooled results were obtained from 3 or 2 independent A549 clonal populations stably transfected with scrambled shRNA (white bars) or 2 anti-IDO shRNA (black bars) respectively, before and after induction of IDO. Each bar represents a mean of 9 (white bars) or 6 (black bars) values ± SEM, Significant difference, Student's t-test, p<0.05. Panel D: Correlation analysis of the relationship between IDO protein content (relative to actin) and clonal population resistance to FK866 (proliferation relative to untreated control cells).