Dioscin-6′-O-acetate inhibits lung cancer cell proliferation via inducing cell cycle arrest and caspase-dependent apoptosis

Lung cancer is the leading cause of global cancer-related mortality. Dioscin-6'-O-acetate (DA), a novel natural steroidal saponin, was firstly isolated from the rhizomes of Dioscorea althaeoides R. Knuth. Until now, there were no studies on its pharmacological activities.Here, we investigated the growth inhibitory effect and explored the underlying molecular mechanisms of DA against lung cancer cells.NSCLC H460, H1299, H520 cells and SCLC H446 cells were treated with DA. To display the cytotoxic effects and possible mechanism of DA on these cells, MTT assay, flow cytometry and western blot analysis were carried out.Our results showed that DA exerted strong anti-proliferative activity against lung cancer cells in a concentration- and time-dependent manner. Flow cytometry demonstrated DA induced the cell cycle arrest at S-phase (NCI-H460, NCI-H1299, NCI-H520) or G1-phase (NCI-H446), caused cellular apoptosis, generation of reactive oxygen species (ROS) and loss of mitochondrial membrane potential. Western blotting analysis showed DA treatment increased the levels of caspase 3, 8, 9, Bax, p21, p53, phosphorylated JNK and p38 MAPK and markedly decreased the expression of Bcl-2, p-ERK, p-PI3K, p-AKT and NF-κB. Blockade of caspases with Z-VAD-FMK converted apoptosis-related proteins. Suppression of p53 with pifithrin-α (PFT) attenuated cell cycle-related protein. Inhibition of ROS with N-acetyl-cysteine (NAC) adjusted apoptosis-related proteins and phosphorylated MAPK and PI3K, as well as NF-κB.Overall, our study indicated that DA suppressed lung cancer cells proliferation via inducing cell-cycle arrest and enhancing caspase-dependent apoptosis, at least partly, through ROS-mediated PI3K/AKT, MAPK and NF-κB signaling pathways.