Gamma-Tocotrienol Stimulates the Proliferation, Differentiation, and Mineralization in Osteoblastic MC3T3-E1 Cells

Gamma-tocotrienol, a major component of tocotrienol-rich fraction of palm oil, has been suggested to exhibit bone protective effects in vivo. However, the effects of gamma-tocotrienol on osteoblast cells are still unclear. In this study, the effects of gamma-tocotrienol on the proliferation, differentiation, and mineralization in osteoblastic MC3T3-E1 cells were investigated. Our results showed that gamma-ocotrienol (2-8.. mol/L) significantly improved the cell proliferation (p < 0.05), but it did not affect cell cycle progression. gamma-Tocotrienol significantly increased alkaline phosphatase (ALP) activity (p < 0.05), secretion levels of osteocalcin (OC) and osteonectin (ON), and mRNA levels of collagen type I (Col I) of MC3T3-E1 cells. Meanwhile, we found that gamma-tocotrienol is promoted in differentiation MC3T3-E1 cells by upregulation of the expression of Runx2 protein. Moreover, the number of bone nodules increased over 2.5-fold in cells treated with gamma-tocotrienol (2-8 mu mol/L) for 24 d compared to control group. These results indicated that gamma-tocotrienol at low dose levels, especially 4 mu mol/L, couldmarkedly enhance the osteoblastic function by increasing the proliferation, differentiation, and mineralization of osteoblastic MC3T3-E1 cells. Moreover, our data also indicated that Runx2 proteinmay be involved in these effects. Further studies are needed to determine the potential of gamma-tocotrienol as an antiosteoporotic agent.