Reverse epithelial-mesenchymal transition contributes to the regain of drug sensitivity in tyrosine kinase inhibitor-resistant non-small cell lung cancer cells.

An-Fu Lee,Man-Chin Chen,Yu-Peng Liu,Chao-Ju Chen,Chih-Jen Yang,Ming-Shyang Huang,Aamir Ahmad

doi:10.1371/journal.pone.0180383

Abstract

Tyrosine kinase inhibitors (TKIs) are currently the first-line treatment for non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations. These patients receive platinum-based chemotherapy as the second-line treatment after they develop resistance to TKIs. Many patients regain sensitivity to the TKIs used in the first-line treatment after the failure of chemotherapy. However, the molecular mechanism for the regain of TKI sensitivity is largely unknown. In this study, we established gefitinib-resistant PC9 and HCC827 cell lines, which did not harbor the EGFR T790M mutation and MET amplification but exhibited the epithelial-mesenchymal transition (EMT) phenotype. Overexpression of EMT inducers, Snail or Slug, in the parental lines promoted their resistance to gefitinib. The gefitinib-resistant cell lines regained their sensitivity to gefitinib and displayed reverse EMT phenotypes after long-term culture in gefitinib-free culture medium. Blockage of reverse EMT by stable expression of Snail or Slug prevented the regain of TKI sensitivity. In conclusion, reverse EMT is one of the major mechanisms for the regain of TKI sensitivity in TKI-resistant NSCLC cells, suggesting that the development of small molecules targeting the EMT process may prolong the efficacy of TKIs in NSCLC patients with EGFR mutations.

Highlights

50% of non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations, such as exon 19 deletion and L858R point mutation, receive tyrosine-kinase inhibitors (TKIs) as their first-line treatment
Epithelial-to-mesenchymal transition occurs in gefitinib-resistant lung cancer cell lines
The forced expression of Slug or Snail blocked the regain of gefitinib sensitivity in the HCC827-WGR subline. These results demonstrated that the regain of gefitinib sensitivity after prolonged withdrawal of gefitinib was mediated by reverse epithelial-mesenchymal transition (EMT) in the TKI-resistant lung cancer cells

Summary

Introduction

50% of non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations, such as exon 19 deletion and L858R point mutation, receive tyrosine-kinase inhibitors (TKIs) as their first-line treatment. Rechallenge with TKIs after the failure of first-line TKI treatment and second-line chemotherapy, referred to as the “TKI holiday”, can improve the survival of patients [3,4,5,6]. This resensitization of the tumor against TKIs occurs in some patients with the T790M mutation, suggesting other mechanisms may play a role in this response [6, 7]. The association between these mechanisms and the regain of TKI sensitivity is largely known

Methods

Results

Conclusion