104 | In vitro crosstalk between perfluorooctanoic acid–induced hypertrophic adipocytes and MCF-7 breast cancer cells

Maria Sofia Molonia¹, Federica Lina Salamone^1|2, Santi Trischitta¹, Antonella Saija¹, Antonio Speciale¹, Francesco Cimino¹ | ¹Department of Chemical, Biological, Pharmaceutical, and Environmental Sciences, University of Messina, Italy; ²Imbesi Foundation, Messina, Italy.

Adipocytes are recognized as active regulators of the tumor microenvironment, playing a critical role in breast cancer development and progression. Through the release of metabolic substrates, adipokines and inflammatory mediators, dysfunctional adipocytes can, in fact, establish a crosstalk with cancer cells, promoting tumor growth, survival and therapy resistance. This interaction is particularly relevant in the context of obesity, a well-established risk factor for breast cancer. Environmental obesogens, such as perfluorooctanoic acid (PFOA), have been implicated in adipose tissue dysfunction. PFOA exposure has been shown to promote adipocyte hypertrophy, metabolic dysfunction and altered adipokine secretion through activation of peroxisome proliferator-activated receptor gamma (PPARγ); however, the indirect effects of these adipocyte-mediated alterations on breast cancer progression remain poorly understood. In this regard, in this study, we investigated the impact of PFOA-induced adipocyte hypertrophy on breast cancer cell behaviour using an in vitro coculture model. 3T3-L1 preadipocytes were exposed to low concentrations of PFOA (0.1-10 µM) throughout the differentiation period to generate hypertrophic mature adipocytes. Subsequently, fully differentiated adipocytes were cocultured with estrogen receptor–positive MCF-7 breast cancer cells using a transwell system, allowing paracrine interaction without direct cell contact. Coculture with PFOA-treated hypertrophic adipocytes significantly increased MCF-7 cell proliferation in a dose-dependent manner, reaching levels comparable to those induced by estradiol, used as a positive control. This proliferative response was associated with activation of PI3K/AKT and ERK proliferative signaling pathways. Furthermore, MCF-7 cells exposed to PFOA-treated adipocytes exhibited a dose-dependent reduction in the cell cycle regulators p53 and p21 and altered apoptotic activity as demonstrated by Bcl-2/Bax ratio increase and reduced caspase-3 activity. Overall, these findings demonstrate that PFOA-induced hypertrophic adipocytes create a pro-tumorigenic microenvironment that enhances proliferation and survival of ER-positive MCF-7 breast cancer cells through coordinated modulation of cell cycle regulators and apoptotic pathways. This study therefore highlights adipocyte-mediated mechanisms as a critical link between environmental obesogen exposure and breast cancer progression, providing new insight into the role of the tumor microenvironment in endocrine-related carcinogenesis.