The extract, LXB-1, from the barks of Liriodendron × hybrid, induced apoptosis via Akt, JNK and ERK1/2 pathways in A549 lung cancer cells.

The effect of LXB-1, an extract from Liriodendron × hybrid, was determined on A549 human lung adenocarcinoma cell lines. Growth inhibition of LXB-1 was analyzed by MTT assay. Cancer cell cycle was measured by flow cytometry. To verify the apoptosis effect of LXB-1 on A549 cells, annexin V/PI double staining assay was performed. The expression levels of proapoptotic proteins were also measured by western blot. The potential mechanisms of LXB-1 inducing apoptosis - the expression and phosphorylation of ERK, p38, JNK and Akt - were investigated by western blot. The IC50 values of LXB-1 on A549 for 24, 48 and 72 h treatment were determined to be 12.97±1.53 µg/mL, 9.55±1.42 µg/mL, and 5.90±0.74 µg/mL, respectively. LXB-1 induced an obvious G2/M cell cycle arrest in A549 cells and resulted in significant cell apoptosis. LXB-1 also increased the cleavage of both caspase-3 and caspase-9, and greatly decreased the protein levels of Bcl-2. Moreover, LXB-1 increased the expression of phosphorylated JNK but decreased the levels of phosphorylated ERK1/2 and Akt. These results suggest that that LXB-1 induced apoptosis through JNK, ERK1/2, and Akt pathways in A549 cells.