Abstract P3-06-02: Exosomes produced by adipocytes induce EMT, immune exhaustion and tumor metastasis, in both in vivo and in vitro models of TNBC

Abstract

Abstract Type 2 Diabetes (T2D) is a chronic inflammatory disease characterized by inflamed adipose tissue. Patients with triple negative breast cancer (TNBC) and comorbid T2D have higher risk of metastasis and shorter survival. However, mechanisms that couple T2D to TNBC outcomes are unknown. Here we hypothesize that exosomes, small vesicles secreted by tumor microenvironment breast adipocytes, drive epithelial-to-mesenchymal transition (EMT) in TNBC, immune exhaustion and metastasis via Ampk-Akt signaling.Methods: Exosomes were purified from conditioned media of 3T3-L1 mature adipocytes that were insulin-sensitive (IS) or insulin-resistant (IR), then characterized and quantified by NanoSight and surface markers, CD63. Murine 4T1 cells, a TNBC model, were treated with exosomes in vitro (3 days). To establish 3D organoids, 4T1 spheroids were treated with exosomes and embedded in Matrigel. For in vivo models, mammary fat pads of BALB/c mice were injected with 4T1 cells treated with IS vs IR exosomes. 4T1 tumors were harvested and mRNA extracted for qPCR, RNAseq, and Ingenuity Pathway Analysis. Metastatic sites in lung and liver were visualized by H&E staining and clonogenic assay. Immune exhaustion markers of tumor infiltrated lymphocytes (TILs) were measured by flow cytometry. Results: In 4T1 cells treated with IR exosomes, EMT was upregulated and PD-L1 expression increased. Tumor-bearing mice exhibited metastasis in exosome-treated groups, visualized by microscopy and clonogenic assay. Immune exhaustion markers showed modified expression in TILs from exosome-treated groups. RNA-seq analysis revealed differences among exosome-treated groups that suggest dysregulated Ampk-Akt pathways.Conclusion: Exosomes from IR adipocytes modify the tumor microenvironment, increase EMT and immune exhaustion markers on tumor cells and TILs, and promote metastasis to distant organs through Ampk-Akt. Metabolic diseases such as T2D reshape the TNBC tumor microenvironment, promoting metastasis and decreasing survival. Clearly, TNBC patients with T2D should be more closely monitored for metastasis than metabolically normal patients, with metabolic medications considered. Citation Format: Yuhan Qiu, Conor Ross, Naser Jafari, Manohar Kolla, Pablo Llevenes, Christina Ennis, Carla S Mazzeo, Kiana Mahdaviani, Naomi Y Ko, Gerald V Denis. Exosomes produced by adipocytes induce EMT, immune exhaustion and tumor metastasis, in both in vivo and in vitro models of TNBC [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-06-02.