Kaempferol suppresses proliferation but increases apoptosis and autophagy by up-regulating microRNA-340 in human lung cancer cells

Abstract Background Lung cancer is a leading cause of cancer-related deaths worldwide with unsatisfied prognosis. Kaempferol is a dietary flavonoid that inhibits tumorgenesis, and we aimed to uncover the underlying mechanism of kaempferol in lung cancer cells. Methods A549 cells were stimulated with kaempferol, and then cell proliferation, apoptosis, autophagy and expression of miR-340 were assessed. Subsequently, effects of kaempferol on protein expression of phosphatase with tensin homology (PTEN) and key kinases in the phosphatidylinositol-3-kinase (PI3K)/AKT pathways were detected by Western blot analysis. Moreover, the effects of miR-340 inhibition on kaempferol-induced alterations in A549 cells were also studied. Results Cell viability, proliferation and cyclinD1 expression level in A549 cells were all reduced by kaempferol. Conversely, cell apoptosis and autophagy were promoted by kaempferol. We found autophagy promoted apoptosis in kaempferol-treated A549 cells. Then, expression of miR-340 was identified to be up-regulated by kaempferol treatment. After treatments with kaempferol, PTEN level was elevated and levels of p-PI3K and p-AKT were decreased. Moreover, the alterations induced by kaempferol were abrogated by miR-340 inhibition. Conclusion Kaempferol inhibited proliferation but induced apoptosis and autophagy in A549 cells. Additionally, kaempferol might function through up-regulating miR-340, along with up-regulation of PTEN and inactivation of the PI3K/AKT pathway.