Abstract PO1-06-13: Plasma Exosomes in Obesity-driven Diabetes Exacerbate Progression of Triple Negative Breast Cancer: Insights from Animal Models
Authors: Llevenes Pablo 
Published: May 2024

Abstract
Objective: Our objective is to examine how obesity and type 2 diabetes (T2D) drive systemic and local metabolic changes in adipose tissue to promote progression of triple negative breast cancer (TNBC). We investigate the role of plasma exosomes as significant mediators of gene expression and functional changes, increasing TNBC progression and metastasis. We hypothesize that T2D and obesity alter the payload of plasma exosomes. These modified exosomes, specifically differentially expressed microRNAs in T2D, critically reshape the tumor microenvironment, ultimately promoting epithelial to mesenchymal transition (EMT) and distant metastasis of TNBC cells. Our goal is to gain a deeper understanding of the underlying mechanisms connecting T2D, obesity and TNBC metastasis, through the novel factor of exosome crosstalk. Our findings shed light on novel therapeutic targets and strategies to mitigate the impact of metabolic disorders on cancer outcomes.
Methods: We subjected C57BL/6J female mice to high-fat diet (HFD; 60% Kcal fat) for 12 weeks with weight monitoring, whereupon oral glucose tolerance test confirmed glucose intolerance and insulin resistance. Plasma exosomes were then isolated from peripheral blood and used to treat E0771 cells, as a TNBC model, for 72 hours for in vitro and in vivo analysis. To assess gene expression changes, we employed a commercial EMT array kit and performed qPCR. Gene expression data were uploaded to Qiagen software, specifically the Ingenuity Pathway Analysis tool, for analysis. To evaluate cell migration as a functional test of aggressiveness, a migration assay was conducted using 24-hour FBS deprivation, followed by 24-hour migration, utilizing transwell plates with 8μm pores. For in vivo analysis, mice were injected with 50k E0771-GFP cells in the 4th mammary fat pad. Tumors were allowed to grow for 28 days, at which time histology and flow cytometry analyses were performed with harvested brain, lung, and spleen.
Results: In-vitro analysis showed that HFD-derived exosomes reprogram gene expression in E0771 cells, driving a strong EMT signature, compared to LFD control or exosome-free negative control. This reprogramming elicited a pro-metastatic phenotype and upregulated signaling pathways associated with metastasis. Furthermore, HFD exosomes upregulated PD-L1 receptor expression compared to negative controls, linking EMT to immune tolerance. In-vivo analysis confirmed these findings, demonstrating increased metastatic burden in both lung and brain in the HFD context.
Conclusions: Plasma exosomes derived from HFD fed mice dramatically reprogram EMT gene networks in E0771 cells, exerting genomic alterations that persist for at least 28 days. These induced changes in cellular gene expression likely promote the development of brain metastases and immune evasion. The model suggests that TNBC patients with obesity-driven diabetes should be evaluated for increased risk of distant metastases. Plasma exosomes miRNA profiling may be a valuable biomarker in cancer disparities populations where the prevalence of obesity and diabetes are high.
Citation Format: Pablo Llevenes. Plasma Exosomes in Obesity-driven Diabetes Exacerbate Progression of Triple Negative Breast Cancer: Insights from Animal Models [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-06-13.