Adipose compounds in breast tumor extracellular matrix

Abstract

Adipocytes constitute the major cell population of adipose tissue (AT),which in turn is an important breast tissue component. Many epidemiological studies support that AT plays a significant role in breast cancer (BCa) development and progression. In fact, several conditions associated with an increase of AT, such as obesity or waist-to-hip ratio, impact on BCa risk, and outcomes. Besides, in the last years, it has been demonstrated that invasive BCa cells modify adjacent adipocytes, becoming cancer-associated adipocytes (CAAs). These cells differ phenotypic and functionally from normal adipocytes, and secrete factors such as adipokines, inflammatory molecules, and microRNAs (miRNAs) that promote a pro-tumoral microenvironment.Moreover, CAAs can regulate processes such as fat distribution, insulin secretion, energy consumption, and inflammatory reactions. Importantly, studieshave revealed that a cyclic crosstalk between adipocytes and BCa cells is established, from which breast tumor feeds back in order to proliferate, invade,and metastasize. Additionally, the altered AT represents a barrier to resistance for BCa treatment. Thus, therapies targeting AT in the context of BCa are currently the subject of extensive study. In this chapter, we will focus on the signaling molecules and the feedback that is established between BCa cells and AT, which allow BCa progression.