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.