Abstract A18: A novel 3D co-culture system for the study of adipocyte and extracellular matrix influences on the breast cancer phenotype
Authors: Pallegar Nikitha Kendyala , Mahendralingam Mathepan , Viloria-Petit Alicia , Christian Sherri 
Published: March 2017

Abstract
Breast cancer (BC) is the most common cancer among women worldwide. Among the different subtypes of breast cancer, triple negative breast cancer (TNBC) is the most aggressive disease. The breast tumor microenvironment, which is mainly composed of extracellular matrix (ECM) and stromal cells such as endothelial cells, immune cells and adipocytes, plays a crucial role in cancer progression. The ECM is considered a major regulator of epithelial architecture and function in mammary gland. ECM stiffness correlates with a more malignant breast cancer phenotype. BC progression is also influenced by other conditions of the patient such as obesity. Obesity increases the number of myofibroblasts in mammary adipose tissue which deposits a stiffer ECM and increases the malignant characteristics of mammary epithelial cells. Obese patients with TNBC have a reduced tendency to respond to therapy leading to poor outcome. The density of the mammary gland in terms of adipocyte to ECM ratio also contributes to breast cancer progression. However, the combined contribution of adipocytes and ECM to the phenotype of transformed mammary epithelium and to cancer progression is rather unexplored. The culture models used so far are limited in their relevance to the in vivo interactions among adipocytes, the ECM and breast cancer cells, and the influence of each of these compartments on each other. Whereas, cells in 3-dimensional (3D) culture models exhibit features that are closer to complex in vivo conditions. In this study, we used a 3D co-culture system comprising adipocyte, ECM and BC cells to understand the function of adipocytes in BC aggressiveness. We determined the effect of mature adipocytes and ECM on epithelial-mesenchymal transition markers in breast cancer cells using immunofluorescence and confocal microscopy. In parallel, we determined the effect of the breast cancer cells on lipid morphology and accumulation in mature adipocytes via Bodipy staining of the lipid droplets and morphology analysis under confocal microscope. We found that ECM and the presence of mature adipocytes modified the phenotype of the BC cells. We also found that the BC cells as well as the ECM modified lipid accumulation in adipocytes. These data show that complex physiological interaction between ECM, adipocytes and BC cells affects the breast cancer phenotype. Thus, the co-culture model described here might serve as a valuable tool to address key questions of TNBC biology, including how the microenvironment in obese patients contributes to TNBC progression, and this may lead to improved therapies for this BC subtype.
Citation Format: Nikitha Kendyala Pallegar, Mathepan Mahendralingam, Alicia Viloria-Petit, Sherri Christian. A novel 3D co-culture system for the study of adipocyte and extracellular matrix influences on the breast cancer phenotype. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr A18.