The function and diagnostic potential of adipocyte-derived factors in the tumor microenvironment

Solid tumors resemble dysfunctional “organs” comprised of malignant cancer cells and heterogeneous components of the tumor microenvironment (TME). The TME includes extracellular matrix and non-cancer stromal cells (e.g., fibroblasts, immune cells, and vascular cells) that may support cancer progression. Adipocytes, despite being the most abundant cell type in certain tumor types (e.g., breast cancer), are often overlooked in the TME. It is now well established that the TME plays an important role in tumor growth and metastasis, and while multiple studies have contributed to our understanding of the TME, relatively little is known about how adipocytes, despite their role as major sources of paracrine and endocrine factors, influence tumor progression. In this chapter, we will briefly introduce the TME and its various components and then provide a comprehensive analysis of the roles of tumor-associated adipocytes and adipokines during solid tumor development. We will also highlight the potential diagnostic/prognostic value of adipose tissue and adipose-derived factors in cancer.