A549 clone sensitivity to methoxyamine (3 mM) before and after IDO induction.

<p>Proliferation of each of 5 individual A549 cell clonal populations before (<b>Panel A</b>) and after (<b>Panel B</b>) IDO induction with IFNγ. A549 clonal populations were cultured with or without IFNγ (25 ng/ml) for 48 h. Cultured medium was then replaced with fresh growth medium containing Methoxyamine (MX) (3 mM) and cells were allowed to proliferate for 72 h. Cells were then trypsinized and live cells were enumerated. <b>White bars</b>: A549 clones transfected with scrambled, non-targeting control shRNA. <b>Gray bars</b>: A549 cells transfected with anti-IDO shRNA. Each bar represents the mean of 3 values (<i>n</i> = 3 for determination of each value) ± SD. Results are normalized to control cells not treated with methoxyamine, without (panel A) or with (panel B) IFNγ treatment. <b>Panel C</b>: Induction of IDO in A549 clonal cell populations induces resistance to MX (3 mM). Results were obtained from 3 or 2 independent clonal cell populations with scrambled, non-targeting control shRNA or anti-IDO shRNA, respectively. Each bar represents a mean of 9 (white bars) or 6 (black bars) values ± SEM, *Significant difference, Student's <i>t</i>-test, <i>p</i><0.05. <b>Panel D</b>: Relationship between IDO protein level (relative to actin) and resistance to methoxyamine (MX)(proliferation relative to untreated control cells). The R² value of 0.83 represents a moderate positive relationship.