The Omega-3 Docosahexaenoyl Ethanolamide Reduces CCL5 Secretion in Triple Negative Breast Cancer Cells Affecting Tumor Progression and Macrophage Recruitment

SIMPLE SUMMARY: Triple-negative breast cancer (TNBC) is associated with a generally poor breast cancer outcome, intensifying the need for novel therapeutic strategies beyond chemotherapy for this challenging subtype of breast cancer. Evidence shows that omega-3 polyunsaturated fatty acids and their derivatives exert antineoplastic effects within the breast tumor microenvironment, highlighting their potential as anticancer agents. Here, we demonstrated that docosahexaenoic acid conjugated with ethanolamine (DHEA) is able to attenuate the malignant phenotype of TNBC cells, reducing cell migration and invasion and affecting their metabolic profile through a shift from an energetic to a quiescent state. In a co-culture system, TNBC cells exposed to DHEA suppressed macrophage recruitment and cell viability along with the expression of genes related to tumor-associated macrophage (TAM) phenotype. Intriguingly, we unraveled that DHEA effects were mediated by CCL5 secretion from TNBC cells, highlighting this molecule as a promising treatment option against TNBC. ABSTRACT: Triple-negative breast cancer (TNBC), an aggressive breast cancer subtype lacking effective targeted therapies, is considered to feature a unique cellular microenvironment with high infiltration of tumor-associated macrophages (TAM), which contribute to worsening breast cancer patient outcomes. Previous studies have shown the antitumoral actions of the dietary omega-3 docosahexaenoic acid (DHA) in both tumor epithelial and stromal components of the breast cancer microenvironment. Particularly in breast cancer cells, DHA can be converted into its conjugate with ethanolamine, DHEA, leading to a more effective anti-oncogenic activity of the parent compound in estrogen receptor-positive breast cancer cells. Here, we investigated the ability of DHEA to attenuate the malignant phenotype of MDA-MB-231 and MDA-MB-436 TNBC cell lines, which in turn influenced TAM behaviors. Our findings revealed that DHEA reduced the viability of TNBC cells in a concentration-dependent manner and compromised cell migration and invasion. Interestingly, DHEA inhibited oxygen consumption and extracellular acidification rates, reducing respiration and the glycolytic reserve in both cell lines. In a co-culture system, TNBC cells exposed to DHEA suppressed recruitment of human THP-1 cells, reduced their viability, and the expression of genes associated with TAM phenotype. Interestingly, we unraveled that the effects of DHEA in TNCB cells were mediated by reduced C-C motif chemokine ligand 5 (CCL5) expression and secretion affecting macrophage recruitment. Overall, our data, shedding new light on the antitumoral effects of DHA ethanolamine-conjugated, address this compound as a promising option in the treatment of TNBC patients.