Figure 3

Inducible PRKDC knockdown decreases human SCLC cell proliferation and is dependent on high MYC expression levels. A) MYC family gene expression levels in non-isogenic SCLC cell lines (as compared to MYC family gene expression levels in 293 T cells). B) SCLC cell lines with different levels of MYC gene expression were treated with varying concentrations of a PRKDC inhibitor, NU-7441, for 3 days and subject to a cell viability assay. C) MYC gene amplification status in different SCLC cell lines. D-G) SCLC cell lines were subjected to inducible PRKDC downregulation with three independent shRNA clones and knockdown was confirmed via immunoblotting and RT-PCR after doxycycline exposure. Protein was analyzed via immunoblotting for PRKDC (anti-PRKDC) and GAPDH (anti-GAPDH). The SCLC cell lines were exposed to doxycycline for 6–13 days and then subjected to a cell viability assay. Data are shown as mean ± SD. Statistical analysis using one-way ANOVA; ****P ≤0.0001; ***P ≤ 0.001; **P ≤ 0.01; *P ≤ 0.05.