Bone Marrow Adipocytes: A Link between Obesity and Bone Cancer

SIMPLE SUMMARY: This review discusses the important newly-established roles for bone marrow adipose tissue in cancer progression and highlights the research demonstrating great promise for clinically targeting the cells in oncology. Bone marrow adipose tissue expands during aging and in obesity. It primarily comprises bone marrow adipocytes (also known as fat cells) and can also contain other cells, such as pre-adipocytes, fibroblasts, macrophages, other immune cells, and endothelial cells. Bone marrow adipocytes are scattered throughout the hematopoietic or “red” marrow, or are densely packed in the marrow cavity, creating “yellow” marrow. Bone marrow biologists are interrogating many questions to understand the nature of bone marrow adipocytes, including how aging and obesity affect these cells; their origins, functions, and endocrine roles; and whether they can be targeted to treat osteoporosis. In parallel, and often in concert, cancer researchers are delineating the role of bone marrow adipocytes in oncology and their potential translational significance for future therapeutics. ABSTRACT: Cancers that grow in the bone marrow are for most patients scary, painful, and incurable. These cancers are especially hard to treat due to the supportive microenvironment provided by the bone marrow niche in which they reside. New therapies designed to target tumor cells have extended the life expectancy for these patients, but better therapies are needed and new ideas for how to target these cancers are crucial. This need has led researchers to interrogate whether bone marrow adipocytes (BMAds), which increase in number and size during aging and in obesity, contribute to cancer initiation or progression within the bone marrow. Across the globe, the consensus in the field is a unified “yes”. However, how to target these adipocytes or the factors they produce and how BMAds interact with different tumor cells are open research questions. Herein, we review this research field, with the goal of accelerating research in the network of laboratories working in this area and attracting bright scientists with new perspectives and ideas to the field in order to bring about better therapies for patients with bone cancers.