Table 2.

Exosomal miRNAs functional activities in cancer. Exosomal miRNAs are secreted by macrophages and cancer cells and affect tumor initiation and progression by targeting key factors involved in survival, proliferation, invasion, and angiogenesis. Macrophage- and tumor-derived exosomal miRNAs recently described in the literature are reported here.

miRNA	Donor Cells	Recipient Cells	Phenotype
miR-21	TAM	gastric cancer cells	↑ cell proliferation ↓ chemosensitivity and apoptosis	TAM-derived exosomal miRNAs
miR-223	TAM	breast cancer cells	↑ cell migration capacity and invasiveness
miR-9	TAM	endothelial cells	↑ cell migration and angiogenesis
miR-940	epithelial ovarian cancer	TAM	↑ M2 polarization	Tumor-secreted exosomal miRNAs
miR-203	colorectal carcinoma	monocytes	↑ M2 polarization
miR-21	solid tumor cells	macrophages	↑ proliferation, survival, invasion and migration
miR-29b	solid tumor cells	macrophages	OncomiR: ↑ secretion of pro-metastatic and pro-inflammatory cytokines
miR-9	tumor cell lines	cancer cells	OncomiR: ↑ endothelial cell migration ↑ tumor angiogenesis
miR-210	breast cancer cells	adjacent cancer cells	OncomiR: ↑ angiogenesis
miR-105	breast cancer cells	endothelial cells of distant organs	OncomiR: ↑ metastasis and vascular permeability by targeting the tight junction protein ZO-1
miR-200	metastatic cancer cells	metastatic cancer cells	Regulates mesenchimal to epithelial transition
let-7e	gastric cancer cells	cancer cells	Tumor suppressor function (i.e., inhibits metastasis)
miR-23b	bladder carcinoma cells	cancer cells	Tumor suppressor function (e.g., inhibition angiogenesis, invasion and metastasis)
miR-224	bladder carcinoma cells	cancer cells	Tumor suppressor functions (e.g., inhibition angiogenesis, invasion and metastasis)
miR-921	bladder carcinoma cells	cancer cells	Tumor suppressor functions (e.g., inhibition angiogenesis, invasion and metastasis)
miR-15a	mesenchymal stromal cells	myeloma cells	Tumor suppressor function