Abstract PO3-24-11: Impact of Circulating Extracellular Vesicles derived from Obese Women on Pro-Tumor Functions of Stromal Fibroblasts in Breast Cancer

Abstract The incidence of obesity has risen sharply worldwide, and growing evidence shows its impact on several malignancies, including breast cancer (BC). Excessive adiposity and high body mass index (BMI) significantly affect BC incidence, prognosis, and therapeutic response of patients. Indeed, obese women exhibit larger tumor size, limph node involvement, metastatic spread, and poorer survival outcomes. Preclinical and clinical studies indicated that the obese setting provides local and systemic modifications that may stimulate BC progression and influence tumor microenvironment, particularly composed of stromal fibroblasts (SF). The mechanisms behind this interplay are likely to be multifactorial and may involve important adipocyte-derived mediators, such as adipokines and growth factors. Aside from these soluble factors, extracellular vesicles (EVs), nanoscale lipid-bilayer enclosed vesicles released by a variety of cells, are emerging as powerful regulators of cell-to-cell communication able to promote BC initiation, growth, metastatic dissemination and drug resistance. However, the potential impact of obesity-derived EVs in affecting tumor-stimulatory features of SF has not been yet investigated. To this aim, circulating EVs were isolated from the serum of women categorized as normal weight (NW; 18 > BMI < 24.9 Kg/m2) and overweight/obese (OW/Ob; BMI > 25 Kg/m2). Immortalised human mammary control fibroblasts (CF), their cancer-associated counterparts (exp-CAFs), and human CAFs, isolated from biopsies of primary BC, were used as experimental models for stromal fibroblasts. Human MCF-7 and T47D BC cells were employed as experimental cell models for mammary carcinoma in co-culture experiments. Circulating EVs were successfully extracted from the serum of NW and OW/Ob women, and characterized by their shapes, size and protein markers. Transmission Electron Microscopy (TEM), and Nanoparticle Tracking Analysis (NTA) showed that EVs in the isolated fractions were oval or bowl-shaped with a size range between 50-200 nm. In accordance with the Minimal Information for Studies of Extracellular Vesicles (MISEV) 2018, enrichment of the EV markers TSG101, CD81, and CD63 were all detected in the EV isolated fractions. Interestingly, elevated levels of circulating EVs were detected in OW/Ob women compared to NW subjects. Treatment of CF with OW/Ob-EVs resulted in an increased cell motility, invasiveness, contractility along with an up-regulation of CF markers. BC cells cocultured with conditioned medium (CM) derived from OW/Ob-EV-treated CF exhibited higher anchorage-independent growth and migratory capacity than BC cells cocultured with CM derived from NW-EV-treated CF. Moreover, OW/Ob-EVs enhanced tumor-stimulatory activities of exp-CAFs and CAFs, further highlighting how obese-related EVs may have the potential to modulate fibroblast phenotype in BC. Finally, cytokine arrays revealed that treatment of CF with OW/Ob EVs was associated with an enhanced release of Fibroblast Growth Factor 19 and Cystatin C, factors that are closely related to BC growth and development. In conclusion, our data provide first evidence for the functional importance of EVs isolated from obese women in impacting tumor-stroma cross-talk and drive BC progression. Since obesity and its pathophysiological sequelae are on the rise, this new knowledge may help to identify specific biomarkers and innovative targets (i.e. FGF-19, and Cystatin C) that may allow a personalized management of patients affected by BC and obesity. Citation Format: Ines Barone, Piercarlo Del Console, Felice Maria Accattatis, Luca Gelsomino, Giuseppina Augimeri, Ennio Avolio, Sebastiano Andò, Daniela Bonofiglio, Cinzia Giordano, Stefania Catalano. Impact of Circulating Extracellular Vesicles derived from Obese Women on Pro-Tumor Functions of Stromal Fibroblasts in Breast Cancer [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 PO3-24-11.