Abstract 3054: Proteomics and microRNA characterization of mammary tumor and adipose tissue-derived EVs and their combined impact on cancer cell metabolism
Authors: Bustamante-Marin Ximena Minerva , Grindstaff Emma J. , Rayyan Laith A. , Teegarden Dorothy , Hursting Stephen 
Published: April 2023

Abstract
Background: Obesity increases the risk of triple negative breast cancer (TNBC) and its progression to metastasis, the primary cause of death in women with TNBC. In obesity, dysregulated adipose tissue secretes growth factors and hormones, promoting chronic inflammation. Adipose tissue also secretes extracellular vesicles (EVs), cell-derived nanoparticles (50 - 5000 nm diameter) containing proteins and nucleic acids that interact with and modify local and distant cellular targets. Research from our team and others demonstrated that the enzyme pyruvate carboxylase (PC) is upregulated during obesity. Moreover, PC upregulation correlates strongly with breast cancer progression to lung metastasis. We hypothesize that tumor and adipose-derived EVs from obese versus normoweight mice regulate PC activity promoting metabolic reprogramming and metastasis.
Methods: Female C57BL/6 mice (n=32) were randomized to receive either control diet (CON) or a diet-indued obesity (DIO) regimen for 15 weeks and then orthotopically injected with metMWntlung cells (a murine model of metastatic TNBC). Half of the mice were sacrificed when the tumor volume reached 0.5 cm3, and the other half at 1 cm3. The EVs from mammary tumors and visceral adipose tissue of CON and DIO mice were purified by differential centrifugation in combination with a flotation Iodixanol density gradient. In parallel, serum-EVs were isolated from the same mice. After proper characterization of the purity of EV by western blot, electron microscopy, and nanotracking analysis, the EV proteomics was analyzed by global LC-MS/MS analysis and the microRNA content by small RNA sequencing.
Results: Preliminary proteomic analysis of adipose-EV identified 2,844 proteins, of which 50% were associated with EV according to GOCC name. In adipose-EV, obesity but not tumor size significantly impacted protein composition. In the comparison DIO-0.5 cm3 versus CON-0.5 cm3, 613 proteins were statistically (p-value &lt; 0.05) and biologically significant. In this comparison, 197 proteins were more abundant, and 412 were less abundant in the DIO-05 cm3 relative to CON-0.5 cm3. In addition, we detected the presence of PC in adipose and tumor-EVs. Ongoing analysis will compare the composition of EVs in more detail, determine the presence of PC regulators in EVs, and the metabolic consequences and metastatic effects of the combined action of adipose- and tumor-derived EVs. R01CA232589 to SDH and DT supports this research; an NCI diversity supplement of this grant supports XBM.
Citation Format: Ximena Minerva Bustamante-Marin, Emma J. Grindstaff, Laith A. Rayyan, Dorothy Teegarden, Stephen Hursting. Proteomics and microRNA characterization of mammary tumor and adipose tissue-derived EVs and their combined impact on cancer cell metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3054.