Lynch, M. E., Brooks, D., Mohanan, S., Lee, M. J., Polamraju, P., Dent, K., Bonassar, L. J., van der Meulen, M. C. H. and Fischbach, C. (2013), In vivo tibial compression decreases osteolysis and tumor formation in a human metastatic breast cancer model. J Bone Miner Res, 28: 2357–2367. doi: 10.1002/jbmr.1966
Biomedical Engineering, Cornell University, Ithaca, NY, USA
Biomedical Sciences, School of Veterinary Medicine, Cornell University, Ithaca, NY, USA
Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA
Research Division, Hospital for Special Surgery, New York, NY, USA
Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA
In vivotibialcompressiondecreasesosteolysis and tumorformation in a humanmetastaticbreastcancermodel.
Bone metastasis, the leading cause of breastcancer-related deaths, is characterized by bone degradation due to increased osteoclastic activity. In contrast, mechanical stimulation in healthy individuals upregulates osteoblastic activity, leading to new bone formation. However, the effect of mechanical loading on the development and progression of metastaticbreastcancer in bone remains unclear. Here, we developed a new in vivomodelto investigate the role of skeletal mechanical stimuli on the development and osteolytic capability of secondary breast tumors. Specifically, we applied compressive loading to the tibia following intratibial injection of metastaticbreastcancer cells (MDA-MB231) into the proximal compartment of female immunocompromised (SCID) mice. In the absence of loading, tibiae developed histologically-detectable tumors with associated osteolysis and excessive degradation of the proximal bone tissue. In contrast, mechanical loading dramatically reduced osteolysis and tumorformation and increased tibial cancellous mass due to trabecular thickening. These loading effects were similar to the baseline response we observed in non-injected SCID mice. In vitro mechanical loading of MDA-MB231 in a pathologically relevant 3D culture model suggested that the observed effects were not due to loading-induced tumor cell death, but rather mediated via decreased expression of genes interfering with bone homeostasis. Collectively, our results suggest that mechanical loading inhibits the growth and osteolytic capability of secondary breast tumors after their homing to the bone, which may inform future treatment of breastcancer patients with advanced disease.