Tumor-suppressive microRNA-218 inhibits tumor angiogenesis via targeting the mTOR component RICTOR in prostate cancer

New insights into the regulatory role of microRNA in tumor angiogenesis and clinical implications

Angiogenesis is essential for tumor growth and metastasis. Understanding the regulation of tumor angiogenesis has become increasingly important. MicroRNAs (miRNAs) are small noncoding RNAs that function in diverse biological processes via post-transcriptional regulation. Extensive studies have revealed two important regulatory roles of miRNAs in tumor angiogenesis: miRNAs in tumor cells affect the activity of endothelial cells via non-cell-autonomous mechanisms, and miRNAs in endothelial cells regulate the cell-autonomous behavior. Recent advances have further highlighted the role of tumor-derived extracellular vesicles in the regulation of tumor angiogenesis via transferring miRNAs to endothelial cells. In this review, we summarize the regulatory role of miRNA in tumor angiogenesis, with a highlight on clinical implications of miRNAs as biomarkers for anti-angiogenic therapy response, and as therapeutic interventions against tumor angiogenesis in vivo.

miRNAs as potential regulators of mTOR pathway in renal cell carcinoma

Renal cell carcinoma (RCC) is the most commonly occurring solid cancer of the adult kidney with the majority of RCC cases being detected accidentally. The most aggressive subtype is clear cell RCC (ccRCC). miRNAs, a family of small noncoding RNAs regulating gene expression have been identified as key biological modulators. The von Hippel-Lindau pathway is one of the signaling pathways involved in the pathophysiology of ccRCC. Another oncogenic mechanism involves the activation of PI3K/AKT/mTOR signaling and serves as a central regulator of cell metabolism, proliferation and survival. Several studies have described the involvement of miRNA dysregulation in the pathogenesis and progression of ccRCC. These molecules can be considered as potential diagnostic and prognostic biomarkers, allowing response to therapy to be monitored.

Circulating pro-angiogenic and anti-angiogenic microRNA expressions in patients with acute ischemic stroke and their association with disease severity

The main objectives of this study are to evaluate 28 selected pro-angiogenic and anti-angiogenic microRNA (miRNA) expressions in plasma of acute ischemic stroke (AIS) patients and controls and to assess the correlations of these miRNAs with risk and severity of AIS. In the exploring stage, 10 AIS patients and 10 controls with vascular risk factors were enrolled. And in the validating stage, 106 AIS patients and 110 controls with the same eligibility were recruited. Blood samples were collected from participants within 24 h post the onset of symptoms, and plasma levels of miRNAs were evaluated by the qPCR method. In the exploring stage, 11 differentially expressed miRNAs (DEM) were identified and included into the validating stage. In the validating stage, the expression of miR-126, miR-130a, and miR-378 in plasma declined in the AIS patients; however, miR-222, miR-218, and miR-185 plasma levels were elevated. Univariate and multivariate logistic regression analysis disclosed that miR-126, miR-130a, miR-222, miR-218, and miR-185 were independent predicting factors for AIS. When these five DEMs were combined together, they presented a good diagnostic value with an area under curve (AUC) value of 0.767 (95% CI 0.705-0.829), sensitivity of 87.7%, and specificity of 54.5% at best cutoff point. Additionally, miR-126, miR-378, miR-101, miR-222, miR-218, and miR-206 were associated with National Institutes of Health Stroke Scale (NIHSS) score. Circulating miR-126, miR-130a, miR-222, miR-218, and miR-185 could be served as promising and independent biomarkers for risk of AIS, and miR-126, miR-378, miR-222, miR-101, miR-218, and miR-206 could be used for disease severity management of AIS.

MicroRNA-140-5p inhibits invasion and angiogenesis through targeting VEGF-A in breast cancer

MicroRNAs (miRNAs) have been proven to be involved in cell metastasis and angiogenesis by interaction with the target mRNAs. Evidence has been confirmed that miR-140-5p is a tumor suppressor in human cancers such as breast cancer. However, the potential molecular mechanism of miR-140-5p in breast cancer invasion and angiogenesis is still poorly understood. According to our study, we reported that miR-140-5p inhibited the tumor invasion and angiogenesis of breast cancer cells both in vitro and in vivo by targeting VEGF-A. The mRNA amount of miR-140-5p was decreased in the breast cancer clinical samples and breast cancer with metastasis compared with the corresponding adjacent normal tissues and cancer without metastasis. MiR-140-5p mimics and a negative control were transfected into human MCF-7 and MDA-MB-231 cells. Transwell chambers were used to detect the invasive ability of the cells, and the angiogenic ability was assessed by tube-formation assay. The markers of invasion and angiogenesis, VEGF-A, CD31 and MMP-9, were detected by using immunohistochemistry and western blot analysis in vivo. VEGF-A was verified as a possible target gene of miR-140-5p, and corroborated by dual-luciferase reporter and ELISA. Taken together, the study elucidates the molecular mechanisms by which miR-140-5p inhibits breast cancer metastasis and angiogenesis, and provides a potent evidence for the development of a novel microRNA-targeting anticancer strategy for breast cancer patients.