Tigogenin Inhibits Adipocytic Differentiation and Induces Osteoblastic Differentiation in Mouse Bone Marrow Stromal Cells

We investigated the effect of tigogenin on adipocytic and osteoblastic differentiation in mouse bone marrow stromal cells (BMSCs). Tigogenin enhanced the proliferation of BMSCs significantly. Tigogenin treatment reduced the adipogenic induction of lipid accumulation, visfatin secretion, and the expressions of peroxisome proliferation-activated receptor (PPAR)gamma2 and adipocyte fatty acid-binding protein (ap)2. Moreover, tigogenin had no effect on the mitotic clonal expansion. On the other hand, tigogenin significantly elevated alkaline phosphatase (ALP) activity and the expressions of Cbfa1, collagen type I (COL I) and osteocalcin (OCN), as well as the content of matrix calcium in BMSCs. Further, SB-203580 antagonized the tigogenin-promoted osteogenesis. These observations suggested that tigogenin may modulate differentiation of BMSCs to cause a lineage shift away from the adipocytes and toward the osteoblasts, which is at least mediated by inhibition of PPARgamma and via p38 MAPK pathway, and is a potential drug preventing the development of osteoporosis and the related disorders.