Effect of miR-200c-3p overexpression on primary human macrophages

Macrophages constitute a major part of the tumor-infiltrating immune cells and within the tumor microenvironment acquire an alternatively activated, tumor-supporting phenotype. Factors released by tumor cells are crucial for the recruitment of tumor-associated macrophages. In the present project, we aimed to understand the role of miR-200c in the interplay between tumor cells and macrophages. To this end, we employed a coculture system of MCF7 breast tumor cells and primary human macrophages and observed a substantial transfer of miR-200c from apoptotic tumor cells to macrophages, which required intact CD36 receptor in macrophages. We further comprehensively determined miR-200c targets in macrophages by mRNA-sequencing and found numerous migration-associated mRNAs to be downregulated by miR-200c. Consequently, miR-200c attenuated macrophage infiltration into 3-dimensional tumor spheroids. The miR-200c-mediated reduction of infiltration further correlated well with a miR-200c migration signature comprised of four miR-200c-repressed targets (PPM1F, RAB11FIB2, RDX, MSN). Overall design: mRNA-seq of primary human macrophages transfected with miR-200c-3p mimic or control harvested 72 h after transfection (n = 4).