Fig. 7.

The signaling pathway inhibitors blocked the effect of EPHA3 deficiency on SCLC chemoresistance. After the stably silenced cells (H69 and H1688 EPHA3 shRNA) were treated with the PI3K-specific inhibitor LY294002 (10 μM, Sigma-Aldrich) for 2 h, we detected the expression of PI3K/BMX/STAT3 protein by Western blotting. The increased expression of p-BMX and p-STAT3 protein levels induced by EPHA3 shRNA in H69 and H1688 cells was blocked by the inhibition of PI3K/BMX pathway with LY294002 (a). The expression of p-PI3K-p85α and total PI3K-p85α in the stably silenced cells simply vanished under exposure to LY294002. Moreover, we evaluated the expression of BMX/STAT3 protein in these stably silenced cells by Western blotting following treatment with BMX inhibitor LFM-A13 (3 μM, Sigma-Aldrich) for 2 h. In the same way, the increased expression of p-STAT3 protein levels induced by EPHA3 shRNA in H69 and H1688 cells was blocked by LFM-A13 (b), accompanied by the disappearance of p-BMX and total BMX expression. Even more, the IC50 values of the stably silenced cells exposure to chemotherapeutic drugs were significantly decreased by CCK-8 assay, whether treated with LY294002 or LFM-A13 (c, d)