Acacetin, one of the
flavonoid compounds, is a natural product found in various plants, including
Silver birch, and Damiana. Previous studies showed that
acacetin has anti-
cancer effects on many kinds of
cancer cells, however, the role of and the mechanisms of actions of
acacetin on
non-small cell lung cancer (NSCLC) cells is still not fully understood. Herein, we found that, in vitro,
acacetin inhibited the proliferation, invasion, and migration of NSCLC cells, A549 and H460, in a dose-dependent manner. Meanwhile, flow cytometry assay results showed that
acacetin induced G2/M phase cell cycle arrest, and apoptosis of NSCLC cells. In vivo,
acacetin suppressed
tumor formation of A549-xenografted nude mice model with no obvious toxicities. Western blotting results showed that the
protein levels of cell cycle-related
proteins cyclin B1,
cyclin D, and
anti-apoptotic protein Bcl-2 had decreased, while the apoptosis-related
protein Bak had increased both in NSCLC cells and in A549-xenografted
tumor tissues. For investigating the molecular mechanism behind the biological effects of
acacetin on NSCLC, we found that
acacetin induced the expression levels of
tumor suppressor p53 both in vitro and in vivo.
MicroRNA, miR-34a, the direct target of p53, has been shown anti-NSCLC proliferation effects by suppressing the expression of its target gene
programmed death ligand 1 (PD-L1). We found that
acacetin upregulated the expression levels of miR-34a, and downregulated the expression levels of PD-L1 of NSCLC cells in vitro and of
tumors in vivo. In vitro, knockdown p53 expression by siRNAs reversed the induction effects of
acacetin on miR34a expression and abolished the inhibitory activity of
acacetin on NSCLC cell proliferation. Furthermore, using agomir and
antagomir to overexpress and suppress the expression miR-34a in NSCLC cells was also examined. We found that miR-34a agomir showed similar effects as
acacetin on A549 cells, while miR-34a
antagomir could partially or completely reverse
acacetin's effects on A549 cells. In vivo, intratumor injection of miR-34a
antagomir could drastically suppress the anti-
tumor formation effects of
acacetin in A549-xenografted nude mice. Overall, our results showed that
acacetin inhibits cell proliferation and induces cell apoptosis of NSCLC cells by regulating miR-34a.