Sulforaphane overcomes T790M-mediated gefitinib resistance in vitro through epithelial-mesenchymal transition.

Abstract

The purpose of the present study was to investigate the effects of sulforaphane (SFN) on gefitinib-resistant cell lines with a T790 mutation (PC-9/AB11). The PC-9 and PC-9/AB11 cells were stained with H&E and visualized with a light microscope. The CCK-8 assay method was used to evaluate the antiproliferative activity of gefitinib and SFN on the cells. Cell cycle arrest and apoptosis were analyzed via flow cytometry. The cytotoxic interaction between the two drugs was evaluated in vitro using the combination index method, and epithelial-mesenchymal transition (EMT)-related proteins and alterations in the signaling pathways were determined by Western blot analysis. Compared to the PC-9 cells, the gefitinib-resistant PC-9/AB11 cells acquired a T790M mutation and had characteristics in accordance with EMT. The combination of gefitinib and SFN induced dose-dependent antiproliferative effects in the PC-9 and PC-9/AB11 cells, while both induced cell cycle arrest and cell apoptosis only in the PC-9/AB11 cells. The synergistic effect in the PC-9/AB11 cells was associated with this drug combination, as it caused an expression change of the epithelial (E-cadherin, claudin-1) and matrix proteins (vimentin, N-cadherin) in the cells, related to the reversal of EMT, as well as an expression change of the epidermal growth factor receptor (EGFR), p-EGFR, p-AKT, and p-ERK proteins. In this study, SFN overcame T790M-mediated gefitinib resistance in vitro through EMT. Thus, a combination of gefitinib and SFN may be a beneficial treatment strategy for lung cancer patients with acquired resistance due to T790M mutation.