Interactions between breast cancer cells and bone marrow derived cells in vitro define a role for osteopontin in affecting breast cancer cell migration

The preferential metastasis of breast cancer cells to bone is a complex set of events including homing and preferential growth which may include unique factors produced by bone cells in the immediate microenvironment. In this study, we evaluated the suitability of bone cells derived from orthoplastic surgeries for use in an in vitro co-culture system representing a model of the bone microenvironment. Using a limiting dilution assay we determined the relative survival and proliferation potentials of breast cancer cell lines co-cultured on bone-derived cells or on Hs68 fibroblasts. The comparison of bone and skin fibroblastic substrata indicates that MCF-7 cells preferentially survive and grow in a bone microenvironment (P < 0.001). Overall, we show that bone-derived cells enhance survival, proliferation, and migration of breast cancer cells, where migration is in part mediated by bone cell-produced osteopontin. Our in vitro co-culture model system provides a robust cost-effective method to study the various factors that mediate cancer/bone-derived cell interactions.