Colorectal cancer cell-secreted exosomal miRNA N-72 promotes tumor angiogenesis by targeting CLDN18

Angiogenesis is essential for the growth and metastasis of several malignant tumors including colorectal cancer (CRC). The molecular mechanism underlying CRC angiogenesis has not been fully elucidated. Emerging evidence indicates that secreted microRNAs (miRNAs) may mediate the intercellular communication between tumor cells and neighboring endothelial cells to regulate tumor angiogenesis. In addition, exosomes have been shown to carry and deliver miRNAs to regulate angiogenesis. miRNA N-72 is a novel miRNA that plays a regulatory role in the EGF-induced migration of human amnion mesenchymal stem cells. However, the relation between miRNA N-72 and cancer remains unclear. We here found that CRC cells could secrete miRNA N-72. A high miRNA N-72 level was detected in the serum of CRC patients and the cultured CRC cells. Moreover, the CRC cell-secreted miRNA N-72 could promote the migration, tubulogenesis, and permeability of endothelial cells. In addition, the mouse xenograft model was used to verify the facilitating effects of miRNA N-72 on CRC growth, angiogenesis, and metastasis in vivo. Further mechanism analysis revealed that CRC cell-secreted miRNA N-72 could be delivered into endothelial cells via exosomes, which then inhibited cell junctions of endothelial cells by targeting CLDN18 and consequently promoted angiogenesis. Our findings reveal a novel mechanism of CRC angiogenesis and highlight the potential of secreted miRNA N-72 as a therapeutic target and a biomarker for CRC.