Caveolin-1 is critical in the proliferative effect of leptin on osteoblasts through the activation of Akt

Osteoblasts are critical in bone remodeling and the repair of bone fractures. Leptin is involved in bone metabolism and osteoblast survival through the downstream signaling pathway, however, the exact mechanism of the effect of leptin on osteoblasts remains to be fully elucidated. In the present study, hFOB 1.19 cells were used to observe the effects of leptin on cell proliferation and apoptosis, and to investigate the underlying mechanism. The results confirmed that treatment of hFOB 1.19 cells with leptin significantly induced cell proliferation. Western blot analysis showed that the expression of caveolin-1 and the activation of Akt in the cells treated with leptin were significantly increased, compared with the control cells. Additionally, inhibiting Akt activation eliminated the effects on cell proliferation induced by leptin. The rates of cell apoptosis and cell cycle distribution were examined using flow cytometry, which revealed a decrease in the apoptotic rate and an increase in the proportion of cells in the S phase. This indicated that leptin was capable of inducing cell proliferation by inhibiting apoptosis and stimulating cell progression to the S phase. Transfection of the cells with caveolin-1 small interfering RNA showed that the activation of Akt induced by leptin was significantly inhibited. Furthermore, caveolin-1 knockdown and inhibiting Akt activation eliminated the increased proliferation, increased proportion of cells in the S phase and increased anti-apoptotic effects induced by leptin. Taken together, the data obtained in the present study demonstrated that caveolin-1 was critical in the proliferative effect of leptin on osteoblasts via the activation of Akt.