Abstract A16: Restoration of gefitinib sensitivity and upregulation of BIM by simvastatin in T790M mutated non-small cell lung cancer cells

Abstract

Abstract Objectives: Epidermal growth factor receptor (EGFR) gene mutation sensitize non-small cell lung cancer (NSCLC) cells to EGFR inhibitors. As the first line treatment on NSCLC, the tyrosine kinase inhibitors (TKIs) are effective, however T790M acquired resistant mutation reduces the therapeutic effect. Statins, 3-hydroxy-3-methyl-gluteryl-CoA (HMG-CoA) reductase inhibitors have pleotrophic effects to induce cell cycle arrest and death in certain type of cancer cells by inhibition of cholesterol synthesis and protein prenylation. The antitumor activities of statin in NSCLC cells inhibiting EGFR signaling proteins including PI3K/Akt and MAPK had been reported, but those in gefitinib resistant lung cancer cells harboring T790M mutation were not known. Recently, BH3-only polypeptide BIM (BCL2 like 11) was reported as one of the molecular mechanisms of T790M resistance in NSCLC cells. This study clarified the roles of simvastatin in the regulation of EGFR signaling and BH3-only protein BIM. Methods: The cytotoxic effects of simvastatin on the gefitinib sensitive (HCC827, E716-A750del) and resistant (H1975, T790M + L858R) NSCLC cells were compared. Cell proliferation, intrinsic apoptosis and the expression of EGFR signaling proteins were evaluated. Expression of BIM was determined with western blot analysis and RT-PCR in H1975 cells after the time-dependent treatment of simvastatin or gefitinib. Results: After the treatment of 2μM simvastatin for 24hrs and 48hrs, H1975 cells showed significantly decreased viability compared to HCC827 cells, (50% vs. 98% and 40% vs. 95%). Expression of Bax, cleaved caspase 3 and p-PARP proteins were increased in H1975 cells which showed the intrinsic apoptosis from simvastatin. Activity of EGFR signaling proteins, phosphorylation of EGFR, Akt and Erk were not affected with 2μM simvastatin for 12, 24 and 48 hours in H1975 cells. With gefitinib (1μM) treatment, BIM was suppressed in H1975 cells compared to HCC827 cells. Notably, BIM was induced after the exposure of simvastatin (2μM) for 12, 24 and 48 hours in H1975 cells. Conclusions: T790M mutation, major mechanism of acquired resistance to EGFR-TKI, was associated with decreased BIM proteins. Simvastatin restored the expression of BIM to induce mitochondrial apoptosis in cells harboring T790M mutation and not in gefitinib sensitive mutation. Our study suggests the possibility of simvastatin to overcome gefitinib resistance with T790M mutation. Citation Format: Mo Jin Young, Lim Jeong Uk, Lee Hwa Young, Kim In Kyoung, Lee Sang Haak. Restoration of gefitinib sensitivity and upregulation of BIM by simvastatin in T790M mutated non-small cell lung cancer cells. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr A16.