Medium-Chain Fatty Acid exposure in non-transformed mammary glands leads to pro-tumorigenic alterations associated with aging.

The local breast environment is a valuable research focus for identifying the etiological and biological factors that contribute to the development of breast cancer. Single-cell RNA sequencing shows that the increased availability of the medium-chain fatty acid octanoic acid induces changes typical of the aged mammary gland, including downregulation of cell-cell junctions, altered extracellular matrix (ECM)-receptor interactions, and upregulation of aging markers like MDK and GDF15. Ex vivo exposure to medium-chain fatty acids compromises cell-cell junctions leading to cell dissemination. As aging is associated with an increased risk of developing breast cancer, it is crucial to identify the factors driving these age-related changes in the mammary gland to develop effective cancer prevention strategies. Given that the proportion of breast adipocytes increases with age, we propose that the remodeling of the mammary gland associated with aging is partly due to the increase in adipocytes and fatty-acid release.