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Cancer Res. 2017 Jul 1;77(13):3527-3539. doi: 10.1158/0008-5472.CAN-16-3470. Epub 2017 May 18.

Targeting FBW7 as a Strategy to Overcome Resistance to Targeted Therapy in Non-Small Cell Lung Cancer.

Author information

1
Department of Pulmonary Medicine, Xijing Hospital, Xi'an, China.
2
State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi'an, China.
3
Department of Occupational and Environmental Health, School of Public Health, Fourth Military Medical University, Xi'an, China.
4
Department of Thoracic Surgery, Tangdu Hospital, Fourth Military Medical University, Xi'an, China.
5
State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi'an, China. zhangjian197011@gmail.com biozhangj@fmmu.edu.cn.
6
Department of Pulmonary Medicine, Xijing Hospital, Xi'an, China. zhangjian197011@gmail.com biozhangj@fmmu.edu.cn.

Abstract

Inhibition of EGFR and anaplastic lymphoma kinase (ALK) signaling is highly effective in a subgroup of non-small cell lung cancer (NSCLC) patients with distinct clinicopathologic features. However, resistance to EGFR and ALK inhibitors inevitably occurs, and the molecular mechanism underlying resistance is not fully understood. In this study, we report a PI3K/Akt- and MEK/ERK-independent resistance mechanism by which loss of the E3 ubiquitin ligase F-box and WD repeat domain containing 7 (FBW7α) leads to targeted therapy resistance via stabilization of antiapoptotic protein MCL-1. Using a panel of in vitro and in vivo studies, we showed that the regulatory machinery responsible for MCL-1 protein degradation was a step-wise event involving phosphorylation and nucleus translocation. ERK cooperated with GSKβ to phosphorylate MCL-1 Ser159 residue, which enabled MCL-1 to translocate into the nucleus and bind FBW7. Defects in this sequence impaired MCL-1 degradation and cell apoptosis, recapitulating phenotypes observed in FBW7 deficiency. Downregulation of FBW7 was found in EGFR inhibitor-resistant human NSCLC specimens and correlated with increased MCL-1 protein expression. Reactivation of FBW7 sensitized resistant cells to targeted therapy and facilitated MCL-1 degradation. Overall, our study provides proof-of-principle insight into a PI3K/Akt- and MEK/ERK-independent resistant model and suggests that targeting FBW7 can overcome resistance to targeted therapy. Cancer Res; 77(13); 3527-39. ©2017 AACR.

PMID:
28522751
DOI:
10.1158/0008-5472.CAN-16-3470
[Indexed for MEDLINE]
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