Abstract
Macamides are a class of bioactive natural products obtained from Lepidium meyenii (maca), which have been reported to exert inhibitory activity in cancer. However, their role in lung cancer is currently unknown. In the present study, macamide B was shown to inhibit the proliferation and invasion of lung cancer cells, as determined by Cell Counting Kit-8 and Transwell assays, respectively. By contrast, macamide B induced cell apoptosis, as determined by Annexin V-FITC assay. Moreover, combined treatment with macamide B and olaparib, an inhibitor of poly (ADP-ribose) polymerase, further suppressed the proliferation of lung cancer cells. At the molecular level, the expression of ataxia-telangiectasia mutated (ATM), RAD51, p53 and cleaved caspase-3 were significantly increased by macamide B, as determined by western blotting, whereas the expression levels of Bcl-2 were decreased. By contrast, when ATM expression was knocked down by small interfering RNA technology in A549 cells treated with macamide B, the expression levels of ATM, RAD51, p53 and cleaved caspase-3 were reduced, whereas those of Bcl-2 were increased. Consistently, cell proliferation and invasive ability were partially rescued by ATM knockdown. In conclusion, macamide B inhibits lung cancer progression by inhibiting cell proliferation and invasion, and inducing apoptosis. Furthermore, macamide B may participate in regulating the ATM signaling pathway. The present study provides a potential new natural drug for treating patients with lung cancer.