Investigation of the effect of macrophage and epithelial cell interaction in the progression of different subtypes of breast cancer.

10 Background: In the realm of tumor progression, the immunosuppressive role of macrophages has been well-established. However, a significant lacuna persists concerning the mechanisms through which epithelial cells regulate macrophages. Furthermore, the precise manner in which macrophages modulate breast cancer cells remains unclear. Hence, the primary objective of the current investigation is to delve into the influence of macrophages on the progression of distinct subtypes of breast cancer. Methods: Human monocyte cell-derived macrophages (M0) were cultivated in the presence of conditioned media (CM) from various subtypes of breast cancer cells. Conversely, human luminal breast cancer cell line T47D, and basal cell line MDA MB 231 were cultured in the presence of CM from macrophages. Results: When macrophages were incubated with CM of T47D, they exhibited a spindle-shaped morphology with pseudopodia. Conversely, exposure to CM of MDA MB 231 induced macrophages to adopt a foamy, round shape with numerous filopodia. Flow cytometry analysis revealed that T47D-CM promoted a higher proportion of CD80+ cells, while MDA MB 231-CM led to an increase in both CD206+ and CD80+ cells. Moreover, both T47D and MDA MB 231-CM escalated the production of various cytokines including IL-1β, IL-2, IL-4, IL-5, IL-7, IL-12(p70), IL-13, IL-17, G-CSF, IFN-γ, and MIP-1β. Intriguingly, MDA MB 231-CM induced a significant increase in IL-6, GM-CSF, and TNF-α. Subsequent cultivation of cancer cells in the presence of macrophage-CM resulted in a marked proliferation of MDA MB 231 cells, while T47D cell proliferation decreased significantly. Correspondingly, there was a notable increase in apoptosis among T47D cells. Scratch wound healing assays revealed heightened migration of MDA MB 231 cells following treatment with macrophage-CM, whereas there was negligible alteration in T47D cell migration. Proteomic analysis unveiled dysregulation of 247 and 596 proteins in MDA MB 231 and T47D cells, respectively. Particularly noteworthy were three proteins—MDHM, H1.5, and LEG8—abundant in MDA MB 231 cells, yet scarce in T47D cells. These proteins have been implicated in promoting tumor growth across various cancer types. Conclusions: This study first time elucidates subtype specific role of macrophage in breast tumour. In triple-negative breast cancer, infiltrating macrophages induce an immunosuppressive effect, altering cytokine expression and fostering the expression of tumor-promoting factors in epithelial cells, thereby facilitating cellular proliferation and metastasis. Conversely, in luminal breast cancer, infiltrating macrophages exhibit a predominantly pro-inflammatory profile, resulting in minimal tumor-promoting effects. Key Words: Breast Cancer, Macrophage polarization, Conditioned Media, Cytokines, Proteomics. Acknowledgements, DBT – Govt of India, NIBMG, Kalyani.