Fig. 1.

Cell-free microRNAs are taken up by cells in the tumour microenvironment.

MicroRNAs are secreted by donor cells through active or passive release mechanisms. These cell-free microRNAs are then taken up by recipient tumour, immune, or stromal recipient cells present in the TME, where they elicit functional effects on gene expression in recipient cells leading to changes in cell proliferation, differentiation, migration, immune response, and angiogenesis that collectively influence tumour progression and metastasis.