Abstract 5889: TWIST1 is a key mediator of HGF-MET-driven resistance to targeted therapies in EGFR mutant and MET-driven lung cancer
Authors: Yochum Zachary A. , Chatterjee Suman , Huang Eric H. , Maurer Deena M. , Attar Myriam A. , Dacic Sanja , Stabile Laura P. , Burns Timothy F. 
Published: August 2018

Abstract
The c-Met (MET) receptor and its ligand, hepatocyte growth factor (HGF), have been shown to mediate epithelial-mesenchymal transition (EMT), proliferation, invasion, motility, and angiogenesis. The HGF/MET pathway is frequently altered in non-small cell lung cancer (NSCLC) and has emerged as a targetable oncogenic driver, as patients with MET amplification and/or mutations have demonstrated marked responses to the MET tyrosine kinase inhibitor (TKI), crizotinib. However, long-term efficacy of MET TKIs is limited as acquired resistance is inevitable and almost half of patients with MET alterations fail to respond to MET TKIs. HGF overexpression has been identified as a mechanism of resistance to both MET and EGFR TKIs in MET altered and EGFR mutant NSCLC. Furthermore, MET amplification has been implicated in EGFR TKI resistance. However, the mechanism(s) by which the HGF-MET pathway causes resistance are poorly understood. We have previously shown that the EMT-transcription factor, TWIST1, is required for MET-driven NSCLC. Here, we investigated the requirement of TWIST1 in HGF-mediated resistance to MET and EGFR TKIs and the role of TWIST1 in de novo and acquired resistance to MET and EGFR TKIs. We found that HGF treatment induced EMT in NSCLC cell lines and increased TWIST1 protein expression through a post-translational mechanism. We demonstrated that targeting TWIST1 pharmacologically with the TWIST1 inhibitor, harmine, overcame HGF-mediated resistance to both MET and EGFR TKIs in MET and EGFR-driven NSCLC. This suggests that TWIST1 is specifically required for HGF-mediated resistance to targeted therapies. We also found that TWIST1 is overexpressed in a subset of MET and EGFR altered cell lines and TWIST1 overexpression was sufficient to cause resistance to MET and EGFR TKIs. In MET-driven and EGFR mutant cell lines that express TWIST1 and are resistant to targeted therapies, we demonstrated that harmine treatment resensitized resistant cells to MET and EGFR TKIs, respectively. To investigate the role of TWIST1 overexpression in Hgf-driven lung cancer, we utilized a CCSP-Hgf (CH) mouse model that constitutively overexpresses Hgf in the lung and develops crizotinib-sensitive tumors following treatment with the tobacco carcinogen, nicotine-derived nitrosamine ketone (NNK). We demonstrated that the Twist1 overexpressing CTH (CCSP-rtTA/Twist1-tetO-luc/CCSP-Hgf) mice developed significantly larger tumors in response to NNK as compared to CH and CCSP-rtTA/Twist1-tetO-luc (CT) mice. In summary, we established that HGF-regulated TWIST1 expression and that TWIST1 expression is required for resistance to MET and EGFR TKIs in the presence and absence of HGF overexpression. These studies suggest that targeting TWIST1 may be an effective therapeutic strategy to overcome HGF-MET-driven resistance in EGFR mutant NSCLC as well as MET TKI resistance in MET-driven NSCLC.
Citation Format: Zachary A. Yochum, Suman Chatterjee, Eric H. Huang, Deena M. Maurer, Myriam A. Attar, Sanja Dacic, Laura P. Stabile, Timothy F. Burns. TWIST1 is a key mediator of HGF-MET-driven resistance to targeted therapies in EGFR mutant and MET-driven lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5889.