Anthracycline Treatments and the Presence of Tumor Cells Synergistically Modify the Composition of Macrophage Subpopulations in the Co-Culture System

In addition to killing malignant cells, effective cancer therapies must also promote the development of an immunostimulatory tumor microenvironment (TME). Macrophages are the most abundant immune cell population within the TME. These highly plastic cells play key roles in tumor progression, chronic inflammation, immunosuppression, and metastasis. Although increasing research efforts focus on manipulating macrophage functions, relatively little is known about how standard anticancer strategies, especially chemotherapeutic agents, influence the composition, polarization state, and functional behavior of macrophage subpopulations. Chemotherapeutic agents remain a primary treatment option for many types of cancer, including breast and cervical cancers. In this study, we used epirubicin and doxorubicin at near-therapeutic concentrations and examined their effects on macrophage functions in co-culture with MDA-MB-231 breast cancer and HeLa cervical cancer cell lines. We demonstrated that the presence of tumor cells led to increased expression of the M2 macrophage marker CD206, a change that was reduced by both chemotherapeutic agents. The production of macrophage-derived chemokines, such as IP-10 and IL-8, was also altered by tumor presence and drug exposure. A striking finding was that the co-presence of chemotherapeutic agents and MDA-MB-231 cells synergistically altered macrophage motility. This effect was not observed in monocultures. Furthermore, the presence of tumor cells reduced the susceptibility of pro-inflammatory M1 macrophages to drug-induced cell death. These results indicate that chemotherapy can reshape the macrophage landscape in the TME. We highlight that the combined effects of tumor cell presence and chemotherapy modulate the composition, phenotype, and migration of macrophage subtypes differently than either factor alone.