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Browne AJ, Kubasch ML, Göbel A, Hadji P, Chen D, Rauner M, Stölzel F, Hofbauer LC, Rachner TD. Concurrent antitumor and bone-protective effects of everolimus in osteotropic breast cancer. Breast Cancer Res 2017; 19:92. [PMID: 28793923 PMCID: PMC5551016 DOI: 10.1186/s13058-017-0885-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/21/2017] [Indexed: 12/20/2022] Open
Abstract
Background The mammalian target of rapamycin inhibitor everolimus is approved as an antitumor agent in advanced estrogen receptor-positive breast cancer. Surrogate bone marker data from clinical trials suggest effects on bone metabolism, but the mode of action of everolimus in bone biology remains unclear. In this study, we assessed potential bone-protective effects of everolimus in the context of osteotropic tumors. Methods The effects of everolimus on cancer cell viability in vitro and on tumor growth in vivo were assessed. Everolimus-regulated osteoclastogenesis and osteoblastogenesis were also assessed in vitro before we assessed the bone-protective effect of everolimus in a model where bone loss was induced in ovariectomized (OVX) mice. Finally, the role of everolimus in the progression of osteolytic bone disease was assessed in an intracardiac model of breast cancer bone metastases. Results At low concentrations (1 nM) in vitro, everolimus reduced the viability of human and murine cancer cell lines and impaired the osteoclastogenesis of osteoclast progenitors as assessed by quantitative real-time polymerase chain reaction and counting tartrate-resistant acid phosphatase-positive, multinucleated osteoclasts (p < 0.001). Everolimus had little or no deleterious effect on osteoblastogenesis in vitro, with concentrations of 1 and 10 nM increasing the messenger RNA expression of osteoblast marker genes (p ≤ 0.05) and leaving mineralization in differentiated human mesenchymal stem cells unchanged. Everolimus treatment (1 mg/kg body weight/day) prevented the bone loss observed in OVX mice and concurrently inhibited the metastatic growth of MDA-MB-231 cells by 70% (p < 0.002) while preserving bone mass in an intracardiac model of bone metastasis. Conclusions These results underline the antitumor effects of everolimus and highlight its bone-protective efficacy, warranting further research on the potential implications on bone health in populations prone to osteoporosis and bone metastases, such as postmenopausal women with breast cancer. Electronic supplementary material The online version of this article (doi:10.1186/s13058-017-0885-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrew J Browne
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany
| | - Marie L Kubasch
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany
| | - Andy Göbel
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany
| | - Peyman Hadji
- Philipps University of Marburg, Marburg, Germany
| | - David Chen
- Novartis Pharmaceutical Corp., East Hanover, NJ, USA
| | - Martina Rauner
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany
| | - Friedrich Stölzel
- Division of Hematology, Department of Medicine I, Technical University Dresden, Dresden, Germany
| | - Lorenz C Hofbauer
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany.,Center for Healthy Aging, Technical University Dresden, Dresden, Germany.,German Cancer Consortium (DKTK), partner site Dresden and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Tilman D Rachner
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine III, Technical University Dresden, Fetscherstraße 74, D-01307, Dresden, Germany. .,Center for Healthy Aging, Technical University Dresden, Dresden, Germany.
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