ABSTRACT
Breast cancer bone metastases are attributed to multiple cellular and molecular interactions between the cancer cells and the bone microenvironment. Some breast cancers (about 10%) manifest predominant osteoblastic bone metastases. However, the effects of cancer cell-produced factors on osteoblastic differentiation are not fully understood. Semaphorin 3A (Sema 3A) is a newly identified regulatory factor of bone rebuilding. In the present study, we demonstrated that human breast cancer MCF-7 cells, which preferentially form osteoblastic bone metastases, exhibited increased Sema 3A expression levels. We also found that MCF-7 cell-derived Sema 3A stimulated osteoblastic differentiation and nuclear ß-catenin accumulation, and these effects could be blocked by shRNA Sema 3A or a Sema 3A-neutralizing antibody. In conclusion, our data suggest that MCF-7 cell-derived Sema 3A plays a causative role in osteoblastic bone metastases progression by stimulating osteoblastic differentiation.
