Effects and mechanism of aromatic aminoketone SY0916 on osteoclastic bone destruction.

Aim: To study the effects and mechanism of aromatic aminoketone (SY0916) on bone destruction in vitro.

Methods: MC3T3-E1 cells and bone marrow cells were co-cultured to obtain purified osteoclasts. The proliferation of osteoclast-like cells (OCLs) was determined by MTT assay. The number of osteoclasts was measured by tartrate-resistant acid phosphatase (TRAP) staining. The functioning of osteoclasts was determined by measuring the area of bone resorption pits on bone slices. MMP-9 secretion by osteoclasts was measured by an ELISA kit. Osteoclast apoptosis was detected by flow cytometry using an AnnexinV-FITC kit. Gene expression of RANK and MMP-9 in osteoclasts as well as RANKL and OPG in MC3T3-E1 cells was determined by real-time PCR.

Results: SY0916 significantly inhibited the proliferation of OCLs, decreased both the total and average area of bone resorption pits, and dramatically inhibited the number of osteoclasts between concentrations of 0.01 and 10 micromol/L. Furthermore, SY0916 reversed IL-1 beta-mediated inhibition of osteoclast apoptosis and shortened osteoclast lifespan. In addition, SY0916 significantly inhibited the mRNA expression of RANK, RANKL, OPG, and MMP-9. However, the inhibition of OPG was weaker than that of RANKL. Accordingly, the ratio of RANKL to OPG mRNA expression in MC3T3-E1 cells was significantly decreased by SY0916. Meanwhile, the expression of MMP-9 protein in osteoclasts was inhibited by SY0916 between 0.01 and 10 micromol/L.

Conclusion: SY0916 prevents osteoclastic bone destruction by inhibiting the proliferation and function of osteoclasts. The underlying mechanism for this effect involves the regulation of the RANKL-OPG-RANK axis, which determines the direction of bone metabolism.