Raspberry ketone promotes the differentiation of C3H10T1/2 stem cells into osteoblasts

The decrease in the bone mass associated with osteoporosis caused by ovariectomy, aging, and other conditions is accompanied by an increase in bone marrow adipose tissue. The balance between osteoblasts and adipocytes is influenced by a reciprocal relationship. The development of modalities to promote local/systemic bone formation by inhibiting bone marrow adipose tissue is important in the treatment of fractures or metabolic bone diseases such as osteoporosis. In this study, we examined whether raspberry ketone [4-(4-hydroxyphenyl)butan-2-one; RK], which is one of the major aromatic compounds of red raspberry and exhibits anti-obesity action, could promote osteoblast differentiation in C3H10T1/2 stem cells. Confluent C3H10T1/2 stem cells were treated for 6 days with 10-100 μg/mL of RK in culture medium containing 10 nM all-trans-retinoic acid (ATRA) or 300 ng/mL recombinant human bone morphogenetic protein (rhBMP)-2 protein as an osteoblast-differentiating agent. RK in the presence of ATRA increased alkaline phosphatase (ALP) activity in a dose-dependent manner. RK in the presence of rhBMP-2 also increased ALP activity. RK in the presence of ATRA also increased the levels of mRNAs of osteocalcin, α1(I) collagen, and TGF-βs (TGF-β1, TGF-β2, and TGF-β3) compared with ATRA only. RK promoted the differentiation of C3H10T1/2 stem cells into osteoblasts. However, RK did not affect the inhibition of early-stage adipocyte differentiation. Our results suggest that RK enhances the differentiation of C3H10T1/2 stem cells into osteoblasts, and it may promote bone formation by an action unrelated to adipocyte differentiation.