Matairesinol repolarizes M2 macrophages to M1 phenotype to induce apoptosis in triple-negative breast cancer cells.

Objective: Triple-Negative Breast Cancer (TNBC), the most challenging subtype of Breast Cancer (BC), currently lacks targeted therapy, presenting a significant therapeutic gap in its management. Tumor Associated Macrophages (TAMs) play a significant role in TNBC progression and could be targeted by repolarizing them from M2 to M1 phenotype. Matairesinol (MAT), a plant lignan, has been shown to exhibit anticancer, anti-inflammatory and immunomodulatory activities. In this study, we explored how MAT-induced repolarization of THP-1-derived M2 macrophages towards the M1 phenotype, which could effectively target the TNBC cell line, MDA-MB-231.

Methods: The differential expression of genes in THP-1-derived macrophages at mRNA levels was evaluated by RNAseq assay. An inverted microscope equipped with a CMOS camera was utilized to capture the morphological variations in THP-1 cells and THP-1-derived macrophages. Relative mRNA expression of M1 and M2 specific marker genes was quantified by qRT-PCR. Cell viability and induction of apoptosis were evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1 dye) assays, respectively.

Results: MAT reduced the viability of M2a and M2d macrophages and repolarized them to M1 phenotype. Conditioned medium (CM) from MAT-treated M2a and M2d macrophages significantly reduced the viability of TNBC cells by apoptosis.

Conclusion: Targeting M2 macrophages is an important strategy to regulate cancer progression. Our study provides evidence that MAT may be a promising drug candidate for developing novel anti-TNBC therapy. However, further studies are warranted to thoroughly elucidate the molecular mechanism of action of MAT and evaluate its therapeutic potential in TNBC in vitro and in vivo models.