Quinoline compound KM11073 enhances BMP-2-dependent osteogenic differentiation of C2C12 cells via activation of p38 signaling and exhibits in vivo bone forming activity.

Seung-Hwa Baek,Sik-Won Choi,Sang-Joon Park,Sang-Han Lee,Seong Hwan Kim,Hang-Suk Chun,Damian Christopher Genetos

doi:10.1371/journal.pone.0120150

Abstract

Recombinant human bone morphogenetic protein (rhBMP)-2 has been approved by the FDA for clinical application, but its use is limited due to high cost and a supra-physiological dose for therapeutic efficacy. Therefore, recent studies have focused on the generation of new therapeutic small molecules to induce bone formation or potentiate the osteogenic activity of BMP-2. Here, we show that [4-(7-chloroquinolin-4-yl) piperazino][1-phenyl-5-(trifluoromethyl)-1H-pyrazol-4-yl]methanone (KM11073) strongly enhances the BMP-2-stimulated induction of alkaline phosphatase (ALP), an early phase biomarker of osteoblast differentiation, in bi-potential mesenchymal progenitor C2C12 cells. The KM11073-mediated ALP induction was inhibited by the BMP antagonist noggin, suggesting that its osteogenic activity occurs via BMP signaling. In addition, a pharmacological inhibition study suggested the involvement of p38 activation in the osteogenic action of KM11073 accompanied by enhanced expression of BMP-2, -6, and -7 mRNA. Furthermore, the in vivo osteogenic activity of KM11073 was confirmed in zebrafish and mouse calvarial bone formation models, suggesting the possibility of its single use for bone formation. In conclusion, the combination of rhBMP-2 with osteogenic small molecules could reduce the use of expensive rhBMP-2, mitigating the undesirable side effects of its supra-physiological dose for therapeutic efficacy. Moreover, due to their inherent physical properties, small molecules could represent the next generation of regenerative medicine.

Highlights

A delicate balance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation is necessary for normal bone development and remodeling
This finding was confirmed by the posttreatment of noggin; when noggin was post-treated alone on differentiation day 4 after BMP-2 and KM11073 treated on differentiation day 0 and 2, noggin dose-dependently and significantly inhibited the alkaline phosphatase (ALP) activity induced by both BMP-2 and KM11073 (Fig. 2C)
An increased risk of complications and adverse events has been suggested for patients receiving Recombinant human bone morphogenetic protein (rhBMP)-2 in spinal fusion, and safety concerns about its clinical application have emerged, including a greater apparent risk of new malignancy with higher doses of Recombinant human BMP-2 (rhBMP-2) [18]

Summary

Introduction

A delicate balance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation is necessary for normal bone development and remodeling. Excessive osteoclastic bone resorption and/or reduced bone formation results in bone loss that leads to pathological bone-related disorders, such as osteoporosis, rheumatoid arthritis, periodontal disease, and cancer bone metastasis [1]. These bone-related disorders impact clinical and public health, most importantly due to subsequent fractures. RhBMP-2 has been approved by the FDA for application in spinal fusion and the treatment of long bone fractures [7, 11], but its clinical use is limited due to its comparatively expensive cost and severe side effects, among other reasons. In the present study, the effect of KM11073 on the commitment of C2C12 cells into osteoblasts was confirmed and potential mechanisms explaining its osteogenic activity investigated

Methods

Results

Conclusion