OBJECTIVETo explore the inhibition and molecular mechanism of icaritin (ICT) combined doxorubicin (DOX) on human osteosarcoma MG-63 cells in vitro.

METHODSThe control group, ICT groups (10, 20, 40, 80, and 160 µmol/L), DOX groups (1, 2, 4, 8, and 16 µg/mL), and combination groups (20 µmol/ L ICT +1 µg/mL DOX, 20 µmol/L ICT +2 µg/mL DOX, 20 µmol/L ICT +4 µg/mL DOX, 40 µmol/L ICT +1 µg/mL DOX, 40 µmol/L ICT +2 µg/mL DOX, 40 µmol/L ICT +4 µg/mL DOX, 80 µmol/L ICT +1 µg/mL DOX, 80 µmol/L ICT +2 µg/mL DOX, 80 µmol/L ICT +4 µg/mL DOX) were set up. Human osteosarcoma MG-63 cells were respectively cultured and their effects on morphological changes were observed using inverted phase contrast microscope after 24-and 48-h intervention. The cell proliferation inhibition rate of each group was de- termined using CCK-8, and IC50 calculated. The MG-63 apoptosis rate was detected using Annexin V-FITC/ PI double dye flow cytometry. Expression levels of bcl-2, caspase-3, and p21 were detected using RT-PCR.

RESULTSICT and DOX could obviously inhibit the proliferation of MG-63 cell. Along with ICT concentration increasing from 10 µmol/L to 160 µmol/L, the cell proliferation inhibition rate also increased gradually from 9.67% ± 3.62% to 89.18% ± 9.66%. The IC50 was 46.93 µmol/L and 3.87 µg/mL respectively. ICT and DOX could cause either early or late stage apoptosis, down-regulate Bcl-2 gene expression, and up-regulate gene expressions of Caspase-3 and p21 respectively (P < 0.05). Aforesaid changes were more obviously seen in combination groups than in lCT groups and DOX groups (P < 0.05).

CONCLUSIONCT combined DOX had additive or synergistic inhibition effect for the proliferation of osteosarcoma MG-63 cells, which might be related with regulating gene expressions of bcl-2, caspase-3, and p21.