N-[2-(4-Acetyl-1-Piperazinyl)Phenyl]-2-(3-Methylphenoxy)Acetamide (NAPMA) Inhibits Osteoclast Differentiation and Protects against Ovariectomy-Induced Osteoporosis

CGK733 alleviates ovariectomy-induced bone loss through blocking RANKL-mediated Ca2+ oscillations and NF-κB/MAPK signaling pathways

Osteoporosis is a prevalent systemic metabolic disease in modern society, in which patients often suffer from bone loss due to over-activation of osteoclasts. Currently, amelioration of bone loss through modulation of osteoclast activity is a major therapeutic strategy. Ataxia telangiectasia mutated (ATM) inhibitor CGK733 (CG) was reported to have a sensitizing impact in treating malignancies. However, its effect on osteoporosis remains unclear. In this study, we investigated the effects of CG on osteoclast differentiation and function, as well as the therapeutic effects of CG on osteoporosis. Our study found that CG inhibits osteoclast differentiation and function. We further found that CG inhibits the activation of NFATc1 and ultimately osteoclast formation by inhibiting RANKL-mediated Ca2+ oscillation and the NF-κB/MAPK signaling pathway. Next, we constructed an ovariectomized mouse model and demonstrated that CG improved bone loss in ovariectomized mice. Therefore, CG may be a potential drug for the prevention and treatment of osteoporosis.

Anti-osteoporotic effects of alisol C 23-acetate via osteoclastogenesis inhibition

Alismatis rhizoma (AR) is the dried rhizome of Alisma orientale (Sam.) Juz. (Alismataceae). This traditional Chinese formula is diuretic, hypoglycemic, and hypolipidemic. Alisol C 23-acetate (AC23A) from AR is anti-inflammatory and ameliorates certain metabolic diseases. However, the mechanism by which AC23A mitigates osteoporosis is unknown. The present study investigated the anti-osteoporotic effects of AC23A in vivo and in vitro. In an ovariectomized (OVX) rat model, AC23A ameliorated OVX-induced organ coefficients and trabecular bone loss. In OVX rats, AC23A treatment lowered serum TRAP5b, CTK, β-CTX, TNF-α, IL-6, and IL-1β, raised serum E2, and did not significantly change serum OCN or BALP. AC23A inhibited osteoclast formation in a rat co-culture system without affecting osteoblast activity. RANK (receptor activator of nuclear factor kappaB) signaling channels are vital osteoclastogenesis transcription elements. AC23A inhibited RANK ligand (RANKL)-induced TRAP, c-Fos, MMP9, NFATc1, and CTK expression and JNK phosphorylation. Therefore, AC23A is anti-osteoclastogenic in vitro and in vivo by inhibiting RANKL-induced osteoclast differentiation and function. Moreover, AC23A could help prevent or limit osteoclast-mediated bone diseases by inhibiting osteoclastogenesis.