Formononetin suppresses the proliferation of human non-small cell lung cancer through induction of cell cycle arrest and apoptosis.

Formononetin is a novel herbal isoflavonoid isolated from Astragalus membranaceus and possesses antitumorigenic properties. In the present study, we investigated the anti-proliferative effects of formononetin on human non-small cell lung cancer (NSCLC), and further elucidated the molecular mechanism underlying the anti-tumor property. MTT assay showed that formononetin treatment significantly inhibited the proliferation of two NSCLC cell lines including A549 and NCI-H23 in a time- and dose-dependent manner. Flow cytometric analysis demonstrated that formononetin induced G1-phase cell cycle arrest and promoted cell apoptosis in NSCLC cells. On the molecular level, we observed that exposure to formononetin altered the expression levels of cell cycle arrest-associated proteins p21, cyclin A and cyclin D1. Meanwhile, the apoptosis-related proteins cleaved caspase-3, bax and bcl-2 were also changed following treatment with formononetin. In addition, the expression level of p53 was dose-dependently upregulated after administration with formononetin. We also found that formononetin treatment increased the phosphorylation of p53 at Ser15 and Ser20 and enhances its transcriptional activity in a dose-dependent manner. Collectively, these results demonstrated that formononetin might be a potential chemopreventive drug for lung cancer therapy through induction of cell cycle arrest and apoptosis in NSCLC cells.