OBJECTIVE To investigate the effect of berberine on ferroptosis in MG63 osteosarcoma cells and its mechanism. METHODS Using cells without drug treatment as control， the cell viability， proliferation， the related indexes of ferroptosis [nuclear proliferation associated-antigen （Ki67）， mitochondrial ultrastructure， ferric ion （Fe2+）， reactive oxygen species （ROS）， malondialdehyde （MDA）， and glutathione （GSH）]， the protein expression of signal transducer and activator of transcription 3 （STAT3）， tumor protein 53 （p53）， and solute carrier family 7 member 11 （SLC7A11） were detected after being treated with different concentrations of berberine. Cells were transfected with p53 siRNA and then assigned to the control group， p53 siRNA group， berberine group， and p53 siRNA+berberine group to explore the role of p53 in berberine-induced ferroptosis. After 24 h incubation with 10.0 μmol/L berberine， the protein expressions of p53 and SLC7A11， the levels of mitochondrial membrane potential， GSH， and MDA content were determined. Cells were transfected with STAT3 overexpressed plasmid and then assigned to the control group， berberine group， STAT3 group， and STAT3+berberine group to explore the effect of STAT3 on the regulation of the p53/SLC7A11 pathway. After 24 h incubation with 10 μmol/L berberine， the protein expressions of p-STAT3， STAT3， p53， and SLC7A11 were detected. RESULTS Compared with the control cell， the concentrations of 2.5， 5.0 and 10.0 μmol/L berberine could reduce the cell viability and expression of Ki67， and induce the morphological changes in ferroptosis-related mitochondria， increase the levels of Fe2+， ROS and MDA， and the protein expression of p53， reduce the level of GSH， the binding activity of STAT3 with DNA， and the protein expressions of p-STAT3 and SLC7A11； the above differences were statistically significant （P＜ 0.05 or P＜0.01）. Compared with the berberine group，significantly down-regulated p53 protein expression and MDA level， up-regulated SLC7A11 protein expression， and increased mitochondrial membrane potential and GSH level were observed in the p53 siRNA+berberine group （P＜0.01）. Compared with the berberine group， the protein expressions of p-STAT3， STAT3， and SLC7A11 in the STAT3+berberine group were significantly increased （P＜0.01）， while the protein expression of p53 was significantly decreased （P＜0.01）. CONCLUSIONS Berberine can induce the ferroptosis of MG63 cells by mediating STAT3/p53/SLC7A11 signaling pathway.

OBJECTIVE To study the mechanism of oxymatrine inducing apoptosis of osteosarcoma MG63 cell line based on mitophagy mediated by cyclooxygenase-2 （COX-2）/PTEN-induced putative kinase-1 （PINK1）/Parkinson disease protein-2 （Parkin） signaling pathway. METHODS MG63 cells were treated with 2.0， 4.0， 8.0 mg/mL oxymatrine and 6 μmol/L 5-fluorouracil， then the apoptotic rate， the expression of apoptosis-related proteins [B-cell lymphoma-2 （Bcl-2）， Bcl-2 related X protein （Bax）]， the proportion of decrease in mitochondrial membrane potential， the level of mitophagy as well as the protein expressions of PINK1， Parkin， and microtubule-associated protein 1 light chain-3Ⅱ （LC3-Ⅱ） were detected. PINK1 small interfering RNA （siRNA） was adopted to intervene in the expression of PINK1， the cells were divided into control group， PINK1 siRNA group， oxymatrine group， and PINK1 siRNA+oxymatrine group； the protein expressions of PINK1， Parkin， and LC3-Ⅱ， the proportion of decrease in mitochondrial membrane potential （MMP） as well as apoptotic rate were detected. The lentivirus infection technique was used to overexpress COX-2， the cells were divided into control group， oxymatrine group， COX-2 group， and COX-2+oxymatrine group. The protein expressions of COX-2， PINK1， and Parkin， as well as the proportion of decrease in MMP were detected. RESULTS After being treated with oxymatrine， the apoptotic rate， the protein expressions of Bax， PINK1， Parkin， and LC3-Ⅱ， the level of mitophagy as well as the proportion of decrease in MMP were significantly increased （P＜0.05）， while the protein expression of Bcl-2 was significantly decreased （P＜0.05）. Compared with the oxymatrine group， the protein expressions of PINK1， Parkin， and LC3-Ⅱ， apoptotic rate and the proportion of decrease in MMP were significantly decreased in PINK1 siRNA+oxymatrine group （P＜0.05）. Compared with the oxymatrine group， the protein expression of COX-2 in the COX-2+oxymatrine group was increased significantly （P＜0.05）， while the protein expressions of PINK1 and Parkin as well as the proportion of 526087266@qq.com decrease in MMP were decreased significantly （P＜0.05）. CONCLUSIONS Oxymatrine can mediate the overactivity of mitophagy based on the PINK1/Parkin signaling pathway by inhibiting COX-2 expression， thus promoting the apoptosis of the MG63 osteosarcoma cell line.