Cyclophosphamide causes osteoporosis in C57BL/6 male mice: suppressive effects of cyclophosphamide on osteoblastogenesis and osteoclastogenesis

// Dongfeng Zhao 1, 2, 3, * , Chenglong Wang 1, 2, 4, * , Yongjian Zhao 1, 2, 3 , Bing Shu 1, 2, 3 , Youji Jia 1, 2 , Shufen Liu 1, 2, 3 , Hongshen Wang 1, 2, 3 , Junli Chang 1, 2, 3 , Weiwei Dai 1, 4 , Sheng Lu 1, 2 , Qi Shi 1, 2, 3 , Yanping Yang 1, 2, 3 , Yan Zhang 1, 2, 3 and Yongjun Wang 1, 2, 3, 5 1 Longhua Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, P.R. China 2 Spine Disease Research Institute, Shanghai University of Traditional Chinese Medicine, Shanghai, P.R China 3 Key Laboratory of Theory and Therapy of Muscles and Bones, Ministry of Education, Shanghai University of Traditional Chinese Medicine, Shanghai, P.R. China 4 Central Laboratory of Research, Longhua Hospital, Shanghai, P.R. China 5 School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, P.R. China * These authors have contributed equally to this work Correspondence to: Yongjun Wang, email: yjwang8888@126.com Yan Zhang, email: medicineyan@aliyun.com Yanping Yang, email: yanpingyangks@163.com Keywords: cyclophosphamide; chemotherapy; osteoporosis; osteoblastogenesis; osteoclastogenesis Received: May 09, 2017     Accepted: August 23, 2017     Published: September 18, 2017 ABSTRACT The clinical evidence indicated that cyclophosphamide (CPD), one of the chemotherapy drugs, caused severe deteriorations in bones of cancer patients. However, the exact mechanisms by which CPD exerts effects on bone remodeling is not yet fully elucidated. Therefore, this study was performed to investigate the role and potential mechanism of CPD in osteoblastogenesis and osteoclastogenesis. Here it was found that CPD treatment (100mg/kg/day) for 7 days led to osteoporosis phenotype in male mice. CPD inhibited osteoblastogenesis as shown by decreasing the number and differentiation of bone mesenchymal stem cells (MSCs) and reducing the formation and activity of osteoblasts. Moreover, CPD suppressed the osteoclastogenesis mediated by receptor activator for nuclear factor-κ B ligand (RANKL) as shown by reducing the maturation and activity of osteoclasts. At the molecular level, CPD exerted inhibitory effect on the expression of components (Cyclin D1, β-catenin, Wnt 1, Wnt10b) of Wnt/β-catenin signaling pathway in MSCs and osteoblasts-specific factors (alkaline phosphatase, Runx2, and osteocalcin). CPD also down-regulated the expression of the components (tumor necrosis factor receptor-associated factor 6, nuclear factor of activated T-cells cytoplasm 1, c-Fos and NF-κB) of RANKL signaling pathway and the factors (matrix metalloproteinase 9, cathepsin K, tartrate-resistant acid phosphates and carbonic anhydrase II) for osteoclastic activity. Taken together, this study demonstrated that the short-term treatment of CPD induced osteoporosis in mice and the underlying mechanism might be attributed to its marked suppression on osteoblastogenesis and osteoclastogenesis, especially the effect of CPD on bone formation might play a dominant role in its detrimental effects on bone remodeling.