Tripchlorolide induces autophagy in lung cancer cells by inhibiting the PI3K/AKT/mTOR pathway and improves cisplatin sensitivity in A549/DDP cells

Abstract

// Li-Min Chen 1, 2, 3 , Tian-Jiao Song 1, 2, 3 , Jian-Hong Xiao 4 , Zheng-Hui Huang 1 , Yong Li 1 and Ting-Yan Lin 1 1 Department of Respiratory Medicine, Fujian Medical University Union Hospital, Fuzhou, Fujian 350001, People’s Republic of China 2 Department of Geriatrics, Fujian Medical University Union Hospital, Fuzhou, Fujian 350001, People’s Republic of China 3 Fujian Institute of Geriatrics, Fujian Medical University Union Hospital, Fuzhou, Fujian 350001, People’s Republic of China 4 Department of Respiratory Medicine, Mindong Hospital of Ningde City, Fu’an, Fujian 355000, People’s Republic of China Correspondence to: Li-Min Chen, email: 13599438522@163.com Ting-Yan Lin, email: tingyanlin58@163.com Keywords: tripchlorolide, autophagy, lung cancer, PI3K/AKT/mTOR, MDR1 Received: November 04, 2016      Accepted: June 20, 2017      Published: July 12, 2017 ABSTRACT Tripchlorolide (T4) has been shown to induce A549 lung cancer cell death predominantly by activating an autophagy pathway. However, the underlying mechanism remains unclear. Herein, we demonstrated that compared with T4 treatment alone, pretreatment with wortmannin (an inhibitor of phosphatidylinositol 3-kinase), perifosine (an inhibitor of AKT) or rapamycin (an inhibitor of mTOR) combined with a subsequent T4 treatment significantly impaired the cell viability of A549 and A549/DDP lung cancer cells. We found that either treatment scheme markedly reduced the activity of P13K and AKT. Expression of LC3II increased in parallel to the increase of the T4 concentration in both A549 and A549/DDP cells and was repressed by overexpression of AKT. The expression levels of PI3-K, PI3-P, AKT, TSC2, mTOR, p70S6K and 4E-BP1 were minimally affected by the wortmannin, perifosine, or rapamycin plus T4 treatments, but their phosphorylated products were greatly affected in A549 lung cancer cells and slightly affected in A549/DDP lung cancer cells. These results indicate that T4 induces autophagy in lung cancer cells by inhibiting the PI3K/AKT/mTOR signaling pathway. We further found that T4 decreased expression of MDR1 and improved cisplatin sensitivity of A549/DDP cells. Altogether, these results have meaningful implications for tumor therapy in the future.