1.1.1.1. Exosomal miRNAs and tumor-associated macrophages (TAMs)
The most abundant immune cell population in the TME is tumor-associated macrophages (TAMs) [36]. TAMs are highly plastic cells that are involved in various actions, including suppressing the immune system, promoting tumor angiogenesis, and increasing resistance of tumor cells to chemotherapy [63, 64]. Poor prognosis in many cancer types is directly related to the number of TAMs in the tumor microenvironment [65]. According to several studies, in several cancer types, including lung, skin, colon, head and neck, bladder, and ovarian cancer, exosomal miRNAs secreted by cancer cells can induce the transition of macrophages to the TAMs [66-71].