Kaempferol inhibits proliferation, migration, and invasion of liver cancer HepG2 cells by down-regulation of microRNA-21

Liver cancer is one of the most common and lethal cancers in human digestive system, which kills more than half a million people every year worldwide. This study aimed to investigate the effects of kaempferol, a flavonoid compound isolated from vegetables and fruits, on hepatic cancer HepG2 cell proliferation, migration, invasion, and apoptosis, as well as microRNA-21 (miR-21) expression. Cell viability was detected using cell counting kit-8 (CCK-8) assay. Cell proliferation was measured using 5-bromo-2′-deoxyuridine (BrdU) incorporation assay. Cell apoptosis was assessed using Guava Nexin assay. Cell migration and invasion were determined using two-chamber migration (invasion) assay. Cell transfection was used to change the expression of miR-21. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to analyze the expressions of miR-21 and phosphatase and tensin homologue (PTEN). Expression of key proteins involved in proliferation, apoptosis, migration, invasion, and phosphatidylinositol 3-kinase/protein kinase 3/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway were evaluated using western blotting. Results showed that kaempferol significantly inhibited HepG2 cell proliferation, migration, and invasion, and induced cell apoptosis. Kaempferol remarkably reduce the expression of miR-21 in HepG2 cells. Overexpression of miR-21 obviously reversed the effects of kaempferol on HepG2 cell proliferation, migration, invasion, and apoptosis. Moreover, miR-21 negatively regulated the expression of PTEN in HepG2 cells. Kaempferol enhanced the expression of PTEN and inactivated PI3K/AKT/mTOR signaling pathway in HepG2 cells. In conclusion, kaempferol inhibited proliferation, migration, and invasion of HepG2 cells by down-regulating miR-21 and up-regulating PTEN, as well as inactivating PI3K/AKT/mTOR signaling pathway.