Niche competition and cancer metastasis to bone.

The molecular basis for the preferential metastases of certain cancers to bone is not well understood. In this issue of the JCI, Shiozawa et al. provide compelling evidence that prostate cancer cells preferentially home to the osteoblastic niche in the bone marrow, where they compete with normal HSCs for niche support. Because signals from the niche may regulate tumor quiescence and sensitivity to chemotherapy, these observations have important implications for the treatment of metastatic prostate cancer in bone.