Epigenetic silencing of miR-126 contributes to tumor invasion and angiogenesis in colorectal cancer
ABSTRACT microRNAs (miRNAs) have been reported to play a crucial role in regulating a variety of genes pivotal for tumor metastasis. miR-126 is well known as one of the angiogenesis regulatory miRNAs. Recent studies have reported controversial roles of miR-126 in tumor progression. In this study, we sought to investigate the potential roles of miR-126 in colorectal cancer (CRC). By real-time PCR, miR-126 was shown to be downregulated in primary CRC tissues and cell lines. Restoration of miR-126 in CRC cells inhibited cell growth, migration and invasion. Using both in silico prediction and immunoblotting, we found that vascular endothelial growth factor (VEGF) was a target of miR-126. The interaction of miR-126 on the 3'UTR of VEGF mRNA was validated by luciferase reporter assay. Mechanistically, we found that the silencing of miR-126 was induced by promoter methyl-ation of its host gene, EGFL7. Treatment with 5-aza-CdR restored miR-126 expression and thereby led to a decline in VEGF expression. Functionally, due to suppression of VEGF, enhanced miR-126 expression inhibited tumor neovasculature triggered by CRC cells. In conclusion, our findings suggest that DNA methylation-induced silencing of miR-126 contributes, at least in part, to tumor invasion and angiogenesis in CRC, through upregulation of VEGF expression. miR-126 may be a potential target for the therapeutic strategy against CRC.
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ABSTRACT: Recent evidence shows that altered microRNA-126 (miR-126) expression is implicated in the progression of colorectal cancer (CRC). However, the precise roles and mechanisms of miR-126 in CRC remain unclear. The aim of this study was to investigate the roles of miR-126 in CRC cells and to elucidate miR-126-mediated mechanisms in CRC cells. First, miR-126 expression was analyzed using qRT-PCR in 4 human CRC cell lines (SW480, SW620, HT-29 and HCT-116). Furthermore, the biological properties of miR-126 in CRC cells in vitro were examined by applying Cell Counting Kit 8, cell cycle, cell apoptosis and transwell assays. The mechanisms and pathways of miR-126-mediated in CRC cells were detected by using qRT-PCR, western blotting and luciferase reporter assay. We found that miR-126 overexpression inhibited cell proliferation, migration and invasion, and induced cell arrest in the G0/G1 phase of CRC cells, suggesting that miR-126 functions as a tumor suppressor in CRC cells. Furthermore, we identified the CXC chemokine receptor 4 (CXCR4) as a target of miR-126, and showed that it was negatively regulated by miR-126. We demonstrated that miR-126-mediated tumor suppression might be partly dependent on AKT and ERK1/2 signaling pathways. In conclusion, our data revealed that miR-126 functions as a tumor suppressor in CRC cells by regulating CXCR4 expression via the AKT and ERK1/2 signaling pathways and might be a novel target for therapeutic strategies in CRC.International Journal of Oncology 11/2013; 44(1). DOI:10.3892/ijo.2013.2168 · 3.03 Impact Factor
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ABSTRACT: Numerous studies have suggested that microRNA-126 (miR-126) is involved in development of various cancer types as well as in malignant proliferation and invasion. However, its role in human prostate cancer (PCa) is still unclear. The aim of this study was to investigate miR-126 expression in PCa and its prognostic value for PCa patients undergoing radical prostatectomy. A series of 128 cases with PCa were evaluated for the expression levels of miR-126 by quantitative reverse-transcription PCR (qRT-PCR). Kaplan-Meier analysis and Cox proportional hazards regression models were used to investigate the correlation between miR-126 expression and prognosis of PCa patients. Compared with non-cancerous prostate tissues, the expression level of miR-126 was significantly decreased in PCa tissues (PCa vs. non-cancerous prostate: 1.05 +/- 0.63 vs. 2.92 +/- 0.98, P < 0.001). Additionally, the loss of miR-126 expression was dramatically associated with aggressive clinical pathological features, including advanced pathological stage (P = 0.001), positive lymph node metastasis (P = 0.006), high preoperative PSA (P = 0.003) and positive angiolymphatic invasion (P = 0.001). Moreover, Kaplan-Meier survival analysis showed that PCa patients with low miR-126 expression have shorter biochemical recurrence (BCR)-free survival than those with high miR-126 expression. Furthermore, multivariate analysis indicated that miR-126 expression was an independent prognostic factor for BCR-free survival after radical prostatectomy. These findings suggest for the first time that the loss of miR-126 expression may play a positive role in the malignant progression of PCa. More importantly, the downregulation of miR-126 may serve as an independent predictor of BCR-free survival in patients with PCa.Virtual slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1740080792113255.Diagnostic Pathology 12/2013; 8(1):208. DOI:10.1186/1746-1596-8-208 · 2.41 Impact Factor
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ABSTRACT: MicroRNAs are powerful gene expression regulators, but their corneal repertoire and potential changes in corneal diseases remain unknown. Our purpose was to identify miRNAs altered in the human diabetic cornea by microarray analysis, and to examine their effects on wound healing in cultured telomerase-immortalized human corneal epithelial cells (HCEC) in vitro. Total RNA was extracted from age-matched human autopsy normal (n=6) and diabetic (n=6) central corneas, Flash Tag end-labeled, and hybridized to Affymetrix® GeneChip® miRNA Arrays. Select miRNAs associated with diabetic cornea were validated by quantitative RT-PCR (Q-PCR) and by in situ hybridization (ISH) in independent samples. HCEC were transfected with human pre-miR(TM)miRNA precursors (h-miR) or their inhibitors (antagomirs) using Lipofectamine 2000. Confluent transfected cultures were scratch-wounded with P200 pipette tip. Wound closure was monitored by digital photography. Expression of signaling proteins was detected by immunostaining and Western blot. Using microarrays, 29 miRNAs were identified as differentially expressed in diabetic samples. Two miRNA candidates showing the highest fold increased in expression in the diabetic cornea were confirmed by Q-PCR and further characterized. HCEC transfection with h-miR-146a or h-miR-424 significantly retarded wound closure, but their respective antagomirs significantly enhanced wound healing vs. controls. Cells treated with h-miR-146a or h-miR-424 had decreased p-p38 and p-EGFR staining, but these increased over control levels close to the wound edge upon antagomir treatment. In conclusion, several miRNAs with increased expression in human diabetic central corneas were found. Two such miRNAs inhibited cultured corneal epithelial cell wound healing. Dysregulation of miRNA expression in human diabetic cornea may be an important mediator of abnormal wound healing.PLoS ONE 12/2013; 8(12):e84425. DOI:10.1371/journal.pone.0084425 · 3.53 Impact Factor