Fig. 4.

Schema of miR-19a-3p regulated Fra-1 gene pathway. miR-19a-3p, which regulates TAMs in the breast tumor microenvironment, is able to regulate the phenotype of TAMs by targeting the Fra-1 gene and other genes in its downstream signaling pathway. IL-6 activates M2 polarization-related signal pathways of TAMs by inhibiting miR-19a-3p expression. The downregulation of miR-19a-3p expression in TAMs is likely due to TME induction, which promotes transformation of M1 to M2 and results in the enhancement of migration and invasion of breast cancer cells