Cancer interaction with the bone microenvironment: A workshop of the National Institutes of Health Tumor Microenvironment Study Section

In this workshop, members of the TME Study Section presented concepts relating to basic bone biology, tumor-stromal interaction, and biology of the bone micro-environment as it relates to the growing metastatic deposit. Recently, it has become clear that several defined vascular elements of the bone marrow are critical with regard to the processes of bone development, organization of the bone microenvironment, and the multifaceted response to perturbations such as fractures or the arrival of metastatic tumor cells. In fact, recent work has identified and even localized various types of stem cells residing in different microenvironmental niches. The stromal response to metastatic cancer cells, in the primary tumor as well as at the metastastic site, is beginning to be defined at the cellular and molecular level. Tumor-associated proteases, growth factors, chemokine receptors, and intracellular communication channels contribute to the tumor-bone interaction. Also, the reciprocal effect of the stroma on tumor cells is a target of investigation. Finally, the bone microenvironment can influence the phenotype of cancer cells in a phenomenon termed osteomimicry. Better definition of tumor-stromal interactions within the bone microenvironment may lead to new avenues of therapy.