Abstract 1276: Inhibition of lipid metabolism decreases proliferation and increases radiosensitvity in EGFR-TKI resistant NSCLC cells with bFGF secretion

Abstract

Abstract Primary and acquired EGFR-TKIs resistance restricts the benefit of EGFR-TKIs to EGFR mutant NSLCLC patients. Recent studies found that metabolic reprogramming might contribute to develop metastasis and drug resistance of tumor cells. Therefore, illustrating the metabolism change is meaningful and targeting the peculiar metabolic pathways might be considered as potential therapeutic strategies for EGFR-TKIs resistant NSCLC. We separated single clones from gefitnib resistant NSCLC cells, by exposing EGFR-mutant EGFR-TKIs sensitive PC-9 cells into increasing concentrations of gefitnib. Among the numerous clones, clone 5 was resistant to gefitinib or AZD9291 and named as PC-9GR-FGF because of high level of bFGF secretion. We found that bFGF promote the transcription of SREBP-1 and its downstream genes, acetyl-CoA carboxylase alpha (ACC), ATP citrate lyase (ACLY) and fatty acid synthase (FASN) in PC-9 cells. Compared to PC-9 cells, higher ACC expression was detected in PC-9GR-FGF cells. Basing on TCGA database (lung Adenocarcinoma, provisional), patients with high ACC expression showed significant shorter PFS (progression-free survival) and OS (overall survival) compared to those with low ACC expression in the EGFR-mutant NSCLC (p<0.05, N=32). Down-regulation of ACC by siRNA or TOFA, a small molecular ACC inhibitor, mederately decreased the proliferation of PC-9 cells whereas strongly decreased proliferation of PC-9GR-FGF cells in vitro and in vivo. Moreover, Reactive oxygen species (ROS) and oxidative stress scavenger, NAC and ferrostatin-1, failed to reverse the effect of ACC inhibition in PC-9 and PC-9GR-FGF cells. Furthermore, after down-regulation or inhibition of ACC, stronger G2/M arrest and more accumulation of DNA damage marker, γH2AX, were found in PC-9GR-FGF cells compared with PC-9 cells. In addition, ACC expression were increased after irradiation of X-ray in PC-9GR-FGF cells, and inhibition of ACC increased accumulation of γH2AX induced by X-rays in PC-9GR-FGF cells. Our research gives a view sight into lipid metabolism changes in EGFR-mutant NSCLC cells before and after acquired EGFR-TKIs resistance, and explores the possibility of combination strategy with radiotherapy and anti-cancer lipid metabolism therapy. Citation Format: Wei Wang, Shunli Peng, Rong Wang, yueyun Ma, Longhui Zhong. Inhibition of lipid metabolism decreases proliferation and increases radiosensitvity in EGFR-TKI resistant NSCLC cells with bFGF secretion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1276.