Abstract 5130: Proteomic characterization of cytoplasmic lipid droplets in human metastatic breast cancer cells

One of the characteristic features of metastatic breast cancer is altered lipid metabolism, including increased cellular storage of neutral lipid in cytoplasmic lipid droplets (CLDs). CLD accumulation is associated with increased cancer aggressiveness, suggesting CLDs contribute to metastasis. Although multiple hypotheses exist for how CLDs may promote cancer progression, how exactly CLDs contribute to breast cancer metastasis is not clear. CLDs are composed of a neutral lipid core, a phospholipid monolayer, and associated proteins. Proteins that associate with CLDs are thought to regulate CLD metabolism; however, the proteome of CLDs in metastatic breast cancer and how these proteins may contribute to altered lipid metabolism and breast cancer progression is unknown. Therefore, we utilized untargeted shotgun proteomics and transmission electron microscopy to identify the proteome and assess the characteristics of CLDs in the MCF10CA1a human metastatic breast cancer cell line. We identified a total number of 1537 proteins in the CLD fraction isolated from MCF10CA1a cells, and these proteins were associated with a variety of cellular processes. Interestingly, unlike other cell lines such as adipocytes or enterocytes, the most enriched protein categories were involved in cellular processes outside of lipid metabolism. For example, proteins involved in cell-cell adhesion were the most enriched in the CLD fraction, and some of these proteins had associated terms in cell migration and signaling. In addition, we characterized CLD size and area in MCF10CA1a cells using transmission electron microscopy. Our results provide a hypothesis-generating list of potential players in breast cancer progression and aggressiveness, making them possible therapeutic targets for prevention or treatment of this disease. Citation Format: Alyssa S. Zembroski, Chaylen Andolino, Kimberly K. Buhman, Dorothy Teegarden. Proteomic characterization of cytoplasmic lipid droplets in human metastatic breast cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5130.