Growth-inhibiting and apoptosis-inducing activities of Myricanol from the bark of Myrica rubra in human lung adenocarcinoma A549 cells.

Myrica rubra (Lour.) Sieb. Et Zucc. is a myricaceae Myrica plant. It is a subtropical fruit tree in China and other Asian countries. The bark of M. rubra is used in Chinese folk medicine because of its antibacterial, antioxidant, anti-inflammatory, and anticancer activities. However, the mechanisms underlying such activities remain unclear. This study investigated whether or not Myricanol extracted from M. rubra bark elicits anti-cancer effects on human lung adenocarcinoma A549 cells by inducing apoptosis in vivo. Myricanol was extracted from M. rubra bark through system solvent extraction and silica gel layer column separation. The results of tritiated thymidine assay, colony formation assay, and flow cytometry indicated that Myricanol inhibited the growth of A549 cells. The effects of Myricanol on the expression of key apoptosis-related genes in A549 cells were evaluated by quantitative PCR and Western blot analyses. Myricanol significantly inhibited the growth of A549 cells in a dose-dependent manner, with a half maximal inhibitory concentration of 4.85 μg/ml. Myricanol significantly decreased colony formation and induced A549 cell apoptosis. Myricanol upregulated the expression of Caspase-3, Caspase-9, Bax, and p21 and downregulated the expression of Bcl-2 at the mRNA and protein levels. These changes were associated with apoptosis. Based on these results, we propose that Myricanol elicits growth inhibitory and cytotoxic effects on lung cancer cells. Therefore, Myricanol may be a clinical candidate for the prevention and treatment of lung cancer.