Supplementary Figure 2 from Role of Survivin in EGFR Inhibitor–Induced Apoptosis in Non–Small Cell Lung Cancers Positive for EGFR Mutations
ARTICLE ABSTRACT
The molecular mechanism by which epidermal growth factor receptor–tyrosine kinase inhibitors (EGFR-TKI) induce apoptosis in non–small cell-lung cancer (NSCLC) cells that are positive for activating mutations of the EGFR remains unclear. In this study, we report the effects of the EGFR-TKI gefitinib on expression of the antiapoptotic protein survivin that have functional consequences in EGFR mutation–positive NSCLC cells. Immunoblot analysis revealed that gefitinib downregulated survivin expression, likely through inhibition of the PI3K-AKT signaling pathway, in NSCLC cells positive for EGFR mutation. Stable overexpression of survivin attenuated gefitinib-induced apoptosis and also inhibited the antitumor effect of gefitinib in human tumor xenografts. Furthermore, the combination of survivin overexpression with inhibition of the gefitinib-induced upregulation of the proapoptotic protein BIM attenuated gefitinib-induced apoptosis to a greater extent than either approach alone. Our results indicate that downregulation of survivin plays a pivotal role in gefitinib-induced apoptosis in EGFR mutation–positive NSCLC cells. Furthermore, they suggest that simultaneous interruption of the PI3K-AKT-survivin and MEK-ERK-BIM signaling pathways is responsible for EGFR-TKI–induced apoptotic death in these cells. Cancer Res; 70(24); 10402–10. ©2010 AACR.
