Exp Mol Med.  2013 Feb;45(2):e9.

Activated protein C differentially regulates both viability and differentiation of osteoblasts mediated by bisphosphonates

• Lee YJ
• Jeong JK
• Seol JW
• Xue M
• Jackson C
• Park SY

Abstract

Activated protein C (APC) is a cytoprotective anticoagulant that can promote cutaneous healing. We examined the effect of APC on viability and differentiation of the osteoblastic line, MG63, in the presence and absence of bisphosphonates (BPs). Osteoblasts were cultured and treated for 24 or 48 h with Alendronate (Aln), Zoledronate (Zol) or Pamidronate (Pam) at concentrations ranging from 10-4 to 10-6 M. Cell differentiation was measured using type 1 collagen production, Alizarin red staining and alkaline phosphatase activity, whereas cell viability was assessed using MTT and crystal violet assays. All three BPs induced MG63 cell death in a dose- and time-dependent manner. Pam- and Zol-related cell death was prevented by APC treatment; however, cell death induced by Aln was accelerated by APC. APC induced MG63 cell differentiation that was enhanced by Aln, but inhibited by Pam or Zol. Endothelial protein C receptor (EPCR) was expressed by MG63 cells and mediated the protective effect of APC on Zol-induced viability. In summary, we have demonstrated that (1) APC favorably regulates MG63 viability and differentiation toward bone growth, (2) APC differentially regulates the effects of specific BPs and (3) at least part of the effects of APC is mediated through EPCR. These findings highlight the potential importance of the PC pathway in bone physiology and provide strong evidence that APC may influence bone cells and has potential to be a therapeutic drug for bone regeneration, depending on concurrent BP treatment.

Keyword

activated protein C; bisphosphonates; EPCR; MG63; osteoblast

MeSH Terms

Antigens, CD/metabolism
Caspases/metabolism
Cell Differentiation/*drug effects
Cell Survival/drug effects
Collagen Type I/metabolism
Diphosphonates/*pharmacology
Extracellular Signal-Regulated MAP Kinases/metabolism
Humans
Matrix Metalloproteinase 2/metabolism
NF-kappa B/metabolism
Osteoblasts/*cytology/*drug effects/enzymology
Protein C/*pharmacology
Receptors, Cell Surface/metabolism
Up-Regulation/drug effects
Antigens, CD
Caspases
Collagen Type I
Diphosphonates
Extracellular Signal-Regulated MAP Kinases
Matrix Metalloproteinase 2
NF-kappa B
Protein C
Receptors, Cell Surface