Abstract
Breast cancer frequently metastasizes to the bone, often leading to the formation of osteolytic lesions. This work compares the paracrine‐induced osteoclastogenesis mediated by four human breast cancer cell lines, the estrogen‐receptor positive T47D and MCF‐7 and the estrogen‐negative SK‐BR‐3 and Hs‐578T cell lines. Human osteoclast precursor cells were cultured in the presence of conditioned media from the breast cancer cell lines (10% and 20%), collected at different culture periods (48 h, 7 days, and 14 days). Cultures performed in the absence or the presence of M‐CSF and RANKL served as negative and positive control, respectively. Results showed that the cell lines differentially expressed several osteoclastogenic genes. All cell lines exhibited a significant osteoclastogenic potential, evidenced by a high TRAP activity and number of osteoclastic cells, expression of several osteoclast‐related genes, and, particularly, a high calcium phosphate resorption activity. Differences among the osteoclastogenic potential of the cell lines were noted. T47D and MCF‐7 cell lines displayed the highest and the lowest osteoclastogenic response, respectively. Despite the variability observed, MEK and NF‐κB signaling pathways, and, at a lesser extent, PGE2 production, seemed to have a central role on the observed osteoclastogenic response. In conclusion, the tested breast cancer cell lines exhibited a high osteoclastogenic potential, although with some variability on the cell response profile, a factor to be considered in the development of new therapeutic approaches for breast cancer‐induced bone metastasis. J. Cell. Biochem. 113: 1069–1079, 2012. © 2011 Wiley Periodicals, Inc.