Influência das vesículas extracelulares liberadas por células tumorais de mama na modulação fenotípica e funcional de monócitos humanos

Abstract

Breast cancer is the most common type among women. Although triple-negative breast cancer (TNBC) is the least common subtype, it is known for its high aggressiveness, poor prognosis, and lack of targeted therapies. The tumor microenvironment (TME) plays a crucial role in supporting and promoting cancer progression. Among the cells present in the TME, monocytes stand out due to their high plasticity and ability to differentiate into tumor-associated macrophages (TAMs). Tumor cells can secrete extracellular vesicles (EVs), which are critical mediators of communication between tumor cells and monocytes. This study aimed to characterize the phenotypic and functional alterations in human monocytes after stimulation with EVs derived from MDA-MB-231 cells, a triple-negative breast cancer cell line. The results showed that exposure to EVs induced marked phenotypic changes in monocytes, with significant expansion of classical CD14++CD16⁻ cells, and reduction of intermediate (CD14+CD16+) and non-classical (CD14⁺⁻CD16⁺) subsets. CX3CR1 expression was increased in all subsets in a TLR4-dependent manner, as its inhibition abolished this effect. EVs also promoted monocyte migration and invasion, and increased MMP-9 expression. Upregulation of CD206 and Arginase-1, and reduced activation of the transcription factor NF-κB, were observed without changes in nitric oxide production. In addition, a decrease in reactive oxygen species (ROS) production was detected, suggesting a functional shift toward M2-like activation. Heat-inactivation of EV proteins reproduced similar effects, indicating a possible role of lipid components in driving these phenotypic changes. Our data suggest that the phenotypic reprogramming of monocytes by MDA-EVs occurs in a TLR4-dependent manner and indicate that a strong lipid component is also involved in this process.