RESUMO
OBJECTIVE To investigate the inhibitory effects of silymarin （SM） on glioma in vivo and in vitro and its potential mechanism. METHODS Human glioma cell line U87 cells were randomly divided into control group， SM low- concentration， SM medium-concentration and SM high-concentration groups （50， 100， 200 μg/mL）， protein kinase B （Akt） activator group （SC79 20 μmol/L）， high-concentration of SM combined with Akt activator group （SM 200 μg/mL+SC79 20 μmol/L）. After drug treatment （except for the control group）， optical density （OD） value， clone formation rate， apoptotic rate， the expressions of proliferation/apoptosis-related proteins [proliferating cell nuclear antigen （PCNA）， B-cell lymphoma-2 （Bcl-2）， Bcl- 2-associated X protein （Bax）， caspase-3]， the phosphorylation levels of Akt/mitogen-activated protein kinase （MAPK） signaling pathway related proteins [Akt， p38 MAPK， extracellular signal-regulated kinase 1/2 （ERK1/2）] were detected in each group. The xenograft tumor model in nude mice was established by injecting U87 cells subcutaneously via the right armpit， and then divided into control group， SM low-dose， SM medium-dose and SM high-dose groups （25， 50， 100 mg/kg）， Akt activator group （SC79 40 mg/kg）， high-dose of SM combined with Akt activator group （SM 100 mg/kg+SC79 40 mg/kg）， with 5 mice in each group. After drug intervention （except for the control group of nude mice）， the tumor mass was weighed and the tumor volume was calculated. RESULTS Compared with control group， the OD values， clone formation rates， protein expressions of PCNA and Bcl- 2， phosphorylation levels of Akt， p38 MAPK and ERK1/2 in SM groups， tumor mass and volume in nude mice of SM groups were all decreased significantly， while the apoptosis rates， protein expressions of Bax and caspase-3 were increased significantly， in a dose-dependent manner （P＜0.05）；the trend of changes in the above indicators in the Akt activator group was opposite （P＜ 0.05）， and Akt activator could significantly attenuate the inhibitory effect of high-concentration/high-dose SM on glioma in vivo and in vitro （P＜0.05）. CONCLUSIONS SM may promote the apoptosis of U87 cells， and inhibit its proliferation， clone formation and tumor growth in xenograft nude mice by inhibiting Akt/MAPK signaling pathway.