Advances in murine models of breast cancer bone disease

Bone is the most prevalent metastatic site for breast cancer affecting ~70% of patients with late-stage disease. Treatments for this condition currently focus on controlling disease progression and limiting tumour-induced damage to bone, thereby playing a valuable role in increasing quality of life. However, limited understanding of the interplay between tumour cells and their environment during bone metastasis has impeded the development of curative treatments. To unravel the complex genetic and phenotypic alterations that occur during this process, it would be helpful to have a model in which tumours develop spontaneously at the primary site, spread to bone, undergo a dormancy phase and then, after a fixed timeframe, become re-activated to form osteolytic/mixed lesions in the skeleton. Unlike humans, spontaneous metastasis of primary mammary tumours to bone is rare in mice and no syngeneic models of oestrogen receptor positive disease have been reported. As there is no single model that authentically reproduces all of the genetic and phenotypic changes representative of human bone metastasis, this review discusses the traditional and novel mouse models that are used to study bone metastasis from breast cancer. Additionally, this review focuses on advances that have been made towards making these models more closely related to human disease in an attempt to help researchers select the correct model(s) for their experimental needs with the aim of improving translational efficacy between the laboratory and the clinic.