Figure 4.

miRNA and Exosomal Effects in Breast Cancer. miRNAs manipulate tumor activity inside breast cancer cells through various downstream effects (shown on left). Inflammatory M1 and TAM M2 macrophages (MØ) within the TME show differential effects based on miRNA expression patterns and changes within each MØ phenotype (left-center, black boxes). Green and red arrows indicate up- or down-regulation of various effects, while black arrows indicate pathways. Exosomal production by the BCCs and M2 MØs within the TME has various effects, including M2 polarization, cell invasion, metastatic progression, and protumoral TME progression (right side, blue arrows). Depending on what miRNAs and exosomal effects are present, it would potentially be possible to switch the TAMs phenotype and thus the TME into a more beneficial state for the host.