Stromal‐derived miR‐486‐5p promotes metastasis of non‐small‐cell lung cancer cells by targeting the CADM1/tight junctions axis in vascular endothelial cells
Bing Sun, Yu Han, Minhua Shi
Abstract
Abstract Serum microRNA has been demonstrated as a noninvasive predictor for the progression of non‐small‐cell lung cancer (NSCLC). The role of microRNA‐486‐5p (miR‐486‐5p) in NSCLC seems to be paradoxical. On the one hand, elevated expression of miR‐486‐5p in serum is associated with unfavorable survival; on the other hand, miR‐486‐5p was notably reduced in NSCLC tissues and acted as a tumor‐suppressor to inhibit NSCLC metastasis. The expression of miR‐486‐5p was analyzed in serum and tissue samples and their relationship was explored. The miR‐486‐5p‐expressing cells were isolated by fluorescent‐activated cell sorting. The downstream target of miR‐486‐5p was identified by bioinformatics prediction and experimental confirmation. Functional studies of miR‐486‐5p on NSCLC metastasis were determined by endothelial permeability assay and trans‐endothelial invasion assay. We found that the expression of miR‐486‐5p was remarkably increased in serum, while dramatically downregulated in tumor tissues of NSCLC. However, the level of miR‐486‐5p in serum was positively correlated with that in tumor tissues. Next, we identified CD31 + vascular endothelial cells in the lung stroma as miR‐486‐5p‐expressing cells. According to bioinformatics prediction, quantitative real‐time reverse transcription PCR, luciferase reporter assay, and western blot, miR‐486‐5p directly targeted the cell adhesion molecule 1/tight junctions axis in vascular endothelial cells. In addition, endothelial permeability assay and trans‐endothelial invasion assay confirmed that miR‐486‐5p promoted NSCLC metastasis. Highly elevated expression of miR‐486‐5p in CD31 + vascular endothelial cells increased vascular permeability and promoted NSCLC metastasis. In conclusion, stromal‐derived miR‐486‐5p is responsible for the paradoxical effect of miR‐486‐5p in serum and tumor tissue.