SYNOPSIS
Statins, cholesterol-lowering drugs, have been recently reported to activate the promoter of the bone morphogenic protein-2 (BMP-2) gene, and stimulate bone formation. In this study, we investigated whether statins promote the mineralization of a subclonal cell line with low differentiation/mineralization potential derived from a murine pro-osteoblastic cell line, MC3T3-E1. Two subclonal cell lines, a nonmineralizing subclone (subclone N) and a mineralizing subclone (subclone M) after growth in the presence of ascorbic acid, were used in this study. Mineralization was detected by von Kossa staining 14 days after the addition of ascorbic acid with or without mevastatin. Total RNA was extracted from the cultured cells 3 days after stimulation, and the mRNA expression level of osteoblast-related molecules was measured using real-time quantitative RT-PCR. Only subclone M formed a mineralized matrix by stimulation of ascorbic acid alone. When mevastatin was added to the ascorbic acid-containing medium, not only subclone M but also subclone N formed a mineralized matrix. The mRNA expression levels of BMP-2 and osteocalcin in subclone N were significantly lower than those in subclone M. When mevastatin was added, both the mRNA levels in subclone N significantly increased, and there was no significant difference between the two subclones. These results demonstrate that statins promote mineralization in nonmineralizing osteoblasts through the induction of BMP-2 and osteocalcin. Hence, statins could be very useful for the promotion of osteoblast differentiation and mineralization in regen-erative bone.

Key words: statin, osteoblast, differentiation, mineralization