TY - JOUR
T1 - The autophagy inhibitor chloroquine overcomes the innate resistance of wild-type EGFR non-small-cell lung cancer cells to erlotinib
AU - Zou, Yiyu
AU - Ling, Yi He
AU - Sironi, Juan
AU - Schwartz, Edward L.
AU - Perez-Soler, Roman
AU - Piperdi, Bilal
N1 - Funding Information:
We thank Ana Maria Cuervo for her critical evaluation of this article and expert advice. This work was supported in part by Pilot and Collaborative Grant from Einstein-Montefiore Institute for Clinical and Translational Research.
PY - 2013/6
Y1 - 2013/6
N2 - Introduction: The epidermal growth factor receptor (EGFR) inhibitor erlotinib is much less effective in non-small-cell lung cancer (NSCLC) tumors with wild-type EGFR, than in tumors with activating EGFR mutations. Autophagy is a tightly regulated lysosomal self-digestion process, which may alternatively promote cell survival or type II cell death. This study assessed the role of autophagy in erlotinib-mediated cytotoxicity. Methods: We used wild-type EGFR erlotinib-sensitive and erlotinib- resistant NSCLC cell lines to determine whether inhibiting autophagy by a therapeutic agent potentiated the antitumor activity of erlotinib in vitro and in vivo. Results: Erlotinib at a clinically relevant concentration (2 μM) induced autophagy in NSCLC cells with wild-type EGFR, and the degree of induction was greater in cells that were resistant than sensitive, suggesting that autophagy is cytoprotective. This was confirmed by knockdown of the autophagy-related gene Atg-5, and by using the autophagy inhibitor chloroquine (CQ), both of which increased the cytotoxicity of erlotinib. The synergistic activity of CQ was not because of the potentiation of erlotinib's effects on autophagy, cell-cycle arrest, and inhibition of both EGFR or downstream signaling of EGFR. Rather, CQ markedly activated apoptosis in the cells. The ability of CQ to potentiate the antitumor activity of erlotinib was also seen in mice bearing NSCLC tumor xenografts. Conclusions: The ability to adapt to anti-EGFR therapy by triggering autophagy may be a key determinant for resistance to erlotinib in wild-type EGFR NSCLC. Inhibition of autophagy by CQ represents a novel strategy to broaden the spectrum of erlotinib efficacy in wildtype EGFR NSCLC tumors.
AB - Introduction: The epidermal growth factor receptor (EGFR) inhibitor erlotinib is much less effective in non-small-cell lung cancer (NSCLC) tumors with wild-type EGFR, than in tumors with activating EGFR mutations. Autophagy is a tightly regulated lysosomal self-digestion process, which may alternatively promote cell survival or type II cell death. This study assessed the role of autophagy in erlotinib-mediated cytotoxicity. Methods: We used wild-type EGFR erlotinib-sensitive and erlotinib- resistant NSCLC cell lines to determine whether inhibiting autophagy by a therapeutic agent potentiated the antitumor activity of erlotinib in vitro and in vivo. Results: Erlotinib at a clinically relevant concentration (2 μM) induced autophagy in NSCLC cells with wild-type EGFR, and the degree of induction was greater in cells that were resistant than sensitive, suggesting that autophagy is cytoprotective. This was confirmed by knockdown of the autophagy-related gene Atg-5, and by using the autophagy inhibitor chloroquine (CQ), both of which increased the cytotoxicity of erlotinib. The synergistic activity of CQ was not because of the potentiation of erlotinib's effects on autophagy, cell-cycle arrest, and inhibition of both EGFR or downstream signaling of EGFR. Rather, CQ markedly activated apoptosis in the cells. The ability of CQ to potentiate the antitumor activity of erlotinib was also seen in mice bearing NSCLC tumor xenografts. Conclusions: The ability to adapt to anti-EGFR therapy by triggering autophagy may be a key determinant for resistance to erlotinib in wild-type EGFR NSCLC. Inhibition of autophagy by CQ represents a novel strategy to broaden the spectrum of erlotinib efficacy in wildtype EGFR NSCLC tumors.
KW - Autophagy inhibitors
KW - Epidermal growth factor receptor
KW - Erlotinib
KW - Non-small-cell lung cancer
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U2 - 10.1097/JTO.0b013e31828c7210
DO - 10.1097/JTO.0b013e31828c7210
M3 - Article
C2 - 23575415
AN - SCOPUS:84879497873
SN - 1556-0864
VL - 8
SP - 693
EP - 702
JO - Journal of Thoracic Oncology
JF - Journal of Thoracic Oncology
IS - 6
ER -