RETRACTED: Kaempferol inhibits proliferation, migration, and invasion of liver cancer HepG2 cells by down-regulation of microRNA-21 (Publication with Expression of Concern. See vol. 35, 2021) (Retracted Article)

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.