The mechanism of RGD-insulin anti-osteoclastic bone resorption

Abstract

Objective: This study is to explore the mechanism of anti-bone resorption of RGD-insulin using multinuclear giant cells (MGC) as a model of osteocalst-like cells (OLCs) in vitro. RGD-insulin is a new polypeptide containing RGD (Arg-Gly-Asp) sequence with insulin-like structure, but it has no physiologic activity of insulin. Methods: OLCs were incubated with 10 −5,10 −6,10 −7 mol/L RGD-insulin for 24 or 48 hours. The OLCs were stained by tartrate-resistant acid phosphatase (TRAP) and acid phosphatase (AP). OLCs were dected by in situ hydridization for the gene expression of carbonic anhydrase II (CA II) and stained by in situ apoptosis using TUNEL. Also attachment tests were performed after RGD-insulin treatment. Results: (1) OLCs and osteoclasts had similar characteristics with multinuclei, TRAP positive and bone resorptive function. (2) RGD-insulin was able to inhibit the attachment function of OLCs and induced OLCs apoptosis in dose dependent manners. (3) 10 −7 mol/L RGD-insulin significantly inhibited the gene expression of CA II, which relative with bone resorption. Conclusion: RGD-insulin induced OLCs apoptosis in dose-dependent manners and the apoptosis of OLCs might be related with the expression of CA II mRNA.