Alteration Of Drug Sensitivity According To The Induction And Reversion Of Epithelialto-Mesenchymal Transition (Emt) In Human Lung Adenocarcinoma Cell Lines Harboring An Egfr Mutation

Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LAIntroduction: EMT phenotype is known to relate to drug resistance and immune tolerance of cancer. However, mechanism underling these phenomena, including the mechanism of the induction and reversion of EMT, are not fully understood.Methods: EGFR mutated human lung adenocarcinoma cell lines, HCC-827 and PC-9, were treated with TGF-s and/or FGF-2 to induce EMT. EMT was reversed by treating the induced EMT cells with either of PP242 (mTOR inhibitor), metformin and DMSO. The phenotypic alterations according to the induction and reversion of EMT were accessed by a wound healing assay for mobility, flow cytometry for cell cycle, MTT and apoptosis assays for drug sensitivity to cisplatin and gefitinib, and RT-PCR and fluorescence IHC for PD-L1 expression.Results: The treatment with combination of TGF-s/FGF-2 showed an efficient increase in expressions of mesenchymal markers and slug in both cell lines, and a decrease in E-cadherin expression in HCC827. In immunoblotting analyses, the Smad3 pathway in PC-9, and the Smad3, MEK/Erk and mTOR pathways in HCC-827 were involved in the induction of the EMT. The induced EMT was accompanied by enhanced cell motility and accumulation in the G0/G1 phases in both cell lines. The induced EMT also made the cells less sensitive to gefitinib in both cell lines, and to cisplatin in HCC-827. Increased PD-L1 expression was observed in both cell lines. Treatment of the induced EMT cells with PP242, metformin and DMSO reverted the altered expressions of epithelial and mesenchymal markers, cell motility and cell cycle. These agents reverted the EMT to different extents and through different pathways, depending on the cell lines. Reversion of the EMT using each of the 3 agents partly restored drug sensitivity, and suppressed PD-L1 expression.Conclusion: Inducing EMT by treatment with TGF-s/FGF-2 is an effective way to acquire drug resistance and up-regulation of PD-L1. Reversion of the EMT, therefore, has a potential to overcome drug resistance and immune tolerance of cancer.Citation Format: Ryota Kurimoto, Shunichiro Iwasawa, Takahiro Ebata, Tsukasa Ishiwata, Ikuo Sekine, Yuji Tada, Koichiro Tatsumi, Shuhei Koide, Atsushi Iwama, Yuichi Takiguchi. Alteration of drug sensitivity according to the induction and reversion of epithelial-to-mesenchymal transition (EMT) in human lung adenocarcinoma cell lines harboring an EGFR mutation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 239.