Erlotinib Activates Different Cell Death Pathways in EGFR-mutant Lung Cancer Cells Grown in 3D<i>Versus</i>2D Culture Systems
Hyun-Kyung Lee, Min Hye Noh, SEUNG-WOO HONG, Seung-Mi Kim, Sung Hyun Kim, Yeong Seok Kim, V. Courtney Broaddus, Dae Young Hur
Abstract
BACKGROUND/AIM: Non-small cell lung cancer patients with epidermal growth factor receptor (EGFR) mutation have been shown to have a good response to erlotinib, a receptor tyrosine kinase inhibitor of EGFR. In this study, we found that the cell death pathways activated by erlotinib in 2D and 3D culture systems are different. MATERIALS AND METHODS: The cell death pathways induced by erlotinib were evaluated by flow cytometry and immunoblotting in both 2D and 3D culture systems of EGFR mutant lung cancer cells. RESULTS: Treatment with erlotinib induced caspase 8 activation and up-regulation of TNF-related apoptosis-inducing ligand (TRAIL) expression only in 3D cultures. Knockdown of TRAIL attenuated both erlotinib-induced activation of caspase-8 and apoptosis in 3D cultures. Erlotinib also increased LC3, an autophagy marker, expression and c-Jun N terminal kinase (JNK) activation. Both 3-MA as an autophagy inhibitor and SP600125 as a JNK inhibitor, significantly inhibited erlotinib-induced cell death. CONCLUSION: Erlotinib induces apoptotic cell death in 3D cultures through an autophagy-TRAIL-JNK pathway.