Effect of miR-21 down-regulated by H 2O 2 on osteogenic differentiation of MC3T3-E1 cells

Abstract

To explore the effect and mechanism of miR-21 down-regulated which was induced by H 2O 2 on osteogenic differentiation of MC3T3-E1 cells. MC3T3-E1 cells were cultured and passaged, and the 7th generation cells were harvested to use in experiment. The MC3T3-E1 cells were treated with different concentrations (0, 40, 80, 160, and 320 μmol/L) of H 2O 2. The expression of miR-21 was detected by real-time quantitative PCR (RT-PCR) and the cell viability was determined by MTS. Then the appropriate concentration of H 2O 2 was obtained. To analyze the effect of H 2O 2 on osteogenic differentiation of MC3T3-E1 cells, the MC3T3-E1 cells were divided into blank control group (group A), H 2O 2 group (group B), osteogenic induction group (group C), and H 2O 2+osteogenic induction group (group D). The expression of miR-21 and the osteogenesis related genes expressions of Runx2, osteopontin (OPN), and collagen type Ⅰ alpha 1 (Col1a1) were detected by RT-PCR. The expression of phosphatase and tensin homolog (PTEN) was detected by Western blot. The extracellular calcium deposition was detected by alizarin red staining. To analyze the effect on osteogenic differentiation of MC3T3-E1 cells after the transfection of miR-21 inhibitor and siRNA-PTEN, the MC3T3-E1 cells were divided into H 2O 2 group (group A1), H 2O 2+osteogenic induction group (group B1), H 2O 2+osteogenic induction+miR-21 inhibitor group (group C1), and H 2O 2+osteogenic induction+miR-21 inhibitor negative control group (group D1); and H 2O 2 group (group A2), H 2O 2+osteogenic induction group (group B2), H 2O 2+osteogenic induction+siRNA-PTEN negative control group (group C2), and H 2O 2+osteogenic induction+siRNA-PTEN group (group D2). The osteogenesis related genes were detected by RT-PCR and the extracellular calcium deposition was detected by alizarin red staining. The results of MTS and RT-PCR showed that the appropriate concentration of H 2O 2 was 160 μmol/L. The expression of miR-21 was significantly lower in group B than in group A at 1 and 2 weeks ( P<0.05). The expression of miR-21 was significantly lower in group D than in group C at 1 and 2 weeks ( P<0.05). The expression of PTEN protein was significantly lower in group C than in groups A and D ( P<0.05). The mRNA expressions of Runx2, OPN, and Col1a1 were significantly lower in group D than in group C at 1 and 2 weeks ( P<0.05). The extracellular calcium deposition in group D was obviously less than that in group C. The expression of PTEN protein was significantly higher in group C1 than in group D1 ( P<0.05). The mRNA expressions of Runx2 and OPN were significantly lower in group C1 than in groups B1 and D1 at 1 and 2 weeks ( P<0.05). The mRNA expression of Col1a1 was significantly lower in group C1 than in groups B1 and D1 at 2 weeks ( P<0.05). The extracellular calcium deposition in group C1 was obviously less than those in groups B1 and D1. The mRNA expressions of OPN and Col1a1 were significantly higher in group D2 than in groups B2 and C2 at 1 week ( P<0.05). The extracellular calcium deposition in group D2 was obviously more than those in groups B2 and C2. H 2O 2 inhibits the osteogenic differentiation of MC3T3-E1 cells, which may be induced by down-regulating the expression of miR-21.