MiRNA-181b suppresses IGF-1R and functions as a tumor suppressor gene in gliomas

MicroRNAs (miRNAs) are single-stranded, 18- to 23-nt RNA molecules that function as regulators of gene expression. Previous studies have shown that microRNAs play important roles in human cancers, including gliomas. Here, we found that expression levels of miR-181b were decreased in gliomas, and we identified IGF-1R as a novel direct target of miR-181b. MiR-181b overexpression inhibited cell proliferation, migration, invasion, and tumorigenesis by targeting IGF-1R and its downstream signaling pathways, PI3K/AKT and MAPK/ERK1/2. Overexpression of IGF-1R rescued the inhibitory effects of miR-181b. In clinical specimens, IGF-1R was overexpressed, and its protein levels were inversely correlated with miR-181b expression. Taken together, our results indicate that miR-181b functions in gliomas to suppress growth by targeting the IGF-1R oncogene and that miR-181b may serve as a novel therapeutic target for gliomas.     

MicroRNA-424 regulates epithelial-mesenchymal transition of endometrial carcinoma by directly targeting insulin-like growth factor 1 receptor

Although numerous miRNAs are reported to contribute to the carcinogenesis of malignant tumor, the specific role of miR-424 in endometrial carcinoma is seldom reported. To explore the effect of miR-424 on epithelial-mesenchymal transition and its underlying mechanism, we detected miR-424 expression in endometrial carcinoma tissue and cells. We found that miR-424 was significantly downregulated in endometrial carcinoma tissues and cells, especially in HEC-1B cells. To perform the functional analysis, we transfected HEC-1B with miR-424-mi, miR-424-inh, mi-control, and inh-control, respectively. We found that overexpression of miR-424 significantly decreases cell proliferation and migration, accompanied with the increased E-cadherin/Vimentin expression and the transition of mesenchymal to epithelial cell phenotype. We identified that insulin-like growth factor-1 receptor (IGF-1R) was a potential target of miR-424 by computational analysis followed by luciferase reporter assays. Of note, we found that the downregulation of miR-424 in HEC-1B cells enhanced endogenous IGF-1R expression. Further mechanistic analysis revealed that forced expression of IGF-1R in miR-424-mim transfected cells remedied the weakened migration resulting from overexpression of IGF-1R. Taken together, the results of the current study demonstrated that miR-424 was a tumor suppressor for endometrial carcinoma and a favorable factor against tumor progression through targeting IGF-1R, thus providing a target for the treatment of endometrial carcinoma.     

LncRNA FENDRR promotes high-glucose-induced proliferation and angiogenesis of human retinal endothelial cells

The study aimed to investigate the role of lncRNA FENDRR in proliferation and angiogenesis of human retinal endothelial cells (HRECs). HRECs were cultured in high-glucose medium to mimic diabetic retinopathy (DR) model. We overexpressed or knocked down FENDRR in HRECs to evaluate the effect of FENDRR expression on cell proliferation, migration, and capillary morphogenesis of HRECs under either normal glucose or high glucose condition. Results showed that VEGF and FENDRR expression were increased in blood from DR patients compared with the control subjects. Furthermore, high glucose treatment upregulated expression of VEGF and FENDRR secreted from HRECs, in a dose- and time-dependent manner. Importantly, FENDRR overexpression significantly promoted the high-glucose-induced proliferation, migration, capillary morphogenesis, and VEGF expression in HRECs. In contrast, FENDRR knockdown exerted the opposite effects. In conclusion, lncRNA FENDRR promotes the high-glucose-induced proliferation and angiogenesis of HRECs and may serve as a potential target for anti-angiogenic therapy for DR.     

miR-223 contributes to the AGE-promoted apoptosis via down-regulating insulin-like growth factor 1 receptor in osteoblasts

Advanced glycation end products (AGEs) have been confirmed to induce bone quality deterioration in diabetes mellitus (DM), and to associate with abnormal expression of miRNAs in DM patients or in vitro. Recently, miRNAs have been recognized to mediate the onset or progression of DM. In the present study, we investigated the regulation on miR-223 level by AGE-BSA treatment in osteoblast-like MC3T3-E1 cells, with real-time quantitative PCR assay. And then we examined the inhibition of insulin-like growth factor 1 receptor (IGF-1R) expression by miR-223, via targeting of the 3′ UTR of IGF-1R with real-time quantitative PCR, western blotting and luciferase reporter assay. Then we explored the regulation of miR-223 and IGF-1R levels, via the lentivirus-mediated miR-223 inhibition and IGF-1R overexpression in the AGE-BSA-induced apoptosis in MC3T3-E1 cells. It was demonstrated that AGE-BSA treatment with more than 100 μg/ml significantly up-regulated miR-223 level, whereas down-regulated IGF-1R level in MC3T3-E1 cells. And the up-regulated miR-223 down-regulated IGF-1R expression in both mRNA and protein levels, via targeting the 3′ UTR of IGF-1R. Moreover, though the AGE-BSA treatment promoted apoptosis in MC3T3-E1 cells, the IGF-1R overexpression or the miR-223 inhibition significantly attenuated the AGE-BSA-promoted apoptosis in MC3T3-E1 cells. In summary, our study recognized the promotion of miR-223 level by AGE-BSA treatment in osteoblast-like MC3T3-E1 cells. The promoted miR-223 targeted IGF-1R and mediated the AGE-BSA-induced apoptosis in MC3T3-E1 cells. It implies that miR-223 might be an effective therapeutic target to antagonize the AGE-induced damage to osteoblasts in DM.     

Fibrin patch-based insulin-like growth factor-1 gene-modified stem cell transplantation repairs ischemic myocardium

Bone marrow mesenchymal stem cells (BMSCs), tissue-engineered cardiac patch, and therapeutic gene have all been proposed as promising therapy strategies for cardiac repair after myocardial infarction. In our study, BMSCs were modified with insulin-like growth factor-1 (IGF-1) gene, loaded into a fibrin patch, and then transplanted into a porcine model of ischemia/reperfusion (I/R) myocardium injury. The results demonstrated that IGF-1 gene overexpression could promote proliferation of endothelial cells and cardiomyocyte-like differentiation of BMSCs in vitro. Four weeks after transplantation of fibrin patch loaded with gene-modified BMSCs, IGF-1 overexpression could successfully promote angiogenesis, inhibit remodeling, increase grafted cell survival and reduce apoptosis. In conclusion, the integrated strategy, which combined fibrin patch with IGF-1 gene modified BMSCs, could promote the histological cardiac repair for a clinically relevant porcine model of I/R myocardium injury.     

AMPK activation inhibits the expression of HIF-1alpha induced by insulin and IGF-1

Insulin, insulin like growth factor (IGF)-1, and AMP-activated protein kinase (AMPK) signaling regulate independently angiogenesis through vascular endothelial growth factor (VEGF) expression. In the present study, we investigated a potential cross-talk between these signaling pathways on hypoxia-inducible factor (HIF)-1alpha and VEGF expression. Retinal epithelial ARPE-19 cells were treated with AICAR, an AMPK activator, alone or in combination with insulin and IGF-1. AICAR stimulated VEGF mRNA expression, but did not modify the insulin- and IGF-1-induced VEGF expression. We have investigated the effect of AICAR on insulin and IGF-1 signaling pathways. We observed that AICAR increased insulin- and IGF-1-induced phosphorylation of PKB, whereas phosphorylation of S6K-1 was decreased. Moreover, AICAR and metformin inhibited the ability of insulin and IGF-1 to induce HIF-1alpha expression. These results show that AICAR and insulin/IGF-1 regulate VEGF expression through different mechanisms.     

MiR-223 Regulates Human Embryonic Stem Cell Differentiation by Targeting the IGF-1R/Akt Signaling Pathway

Currently, there are difficulties associated with the culturing of pluripotent human embryonic stem cells (hESCs), and knowledge regarding their regulatory mechanisms is limited. MicroRNAs (miRNAs) regulate gene expression and have critical functions in stem cell self-renewal and differentiation. Moreover, fibroblast growth factor (FGF) and the insulin-like growth factor receptor (IGF-1R) are key activators of signaling in hESCs. Based on the identification of complementary binding sites in miR-223 and IGF-1R mRNA, it is proposed that miR-223 acts as a local regulator of IGF-1R. Therefore, levels of miR-223 were detected in differentiated versus undifferentiated hESCs. In addition, proliferation, apoptosis, and differentiation were assayed in these two hESC populations and were compared in the presence of exogenous miR-223 and miR-223 inhibitor. Inhibition of miR-223 was found to maintain the undifferentiated state of hESCs, while addition of miR-223 induced differentiation. Furthermore, these effects were found to be likely dependent on IGF-1R/Akt signaling.     

Polycomb chromobox 4 enhances migration and pulmonary metastasis of hepatocellular carcinoma cell line MHCC97L

We recently report that the expression of polycomb chromobox 4(Cbx4)is significantly correlated with the overall survival of a great cohort of hepatocellular carcinoma(HCC)patients and it enhances hypoxia-induced vascular endothelial growth factor(VEGF)expression and angiogenesis in HCC cells through enhancing sumoylation of hypoxia inducible factor-1alpha(HIF-1α).Here we continue to investigate the potential effects of Cbx4 on the migration and metastasis of the metastatic HCC cell line MHCC97L.Our results show that Cbx4 overexpression in the cell line increases the in vitro vessel formation of vascular endothelial cells in its SUMO interaction motifs-dependent manner,and promotes the in vitro migration of the cancer cell,which can be effectively abrogated by anti-VEGF antibody.Although Cbx4 expression does not impact the in vitro growth of MHCC97L cells,it still promotes the progression and metastasis of orthotopically transplanted tumors in nude mice.These results further support the role of Cbx4 as a SUMO E3 ligase in the progression and metastasis of HCC.     

miRNA-27b Targets Vascular Endothelial Growth Factor C to Inhibit Tumor Progression and Angiogenesis in Colorectal Cancer

Colorectal cancer (CRC) is one of the most prevalent cancers globally and is one of the leading causes of cancer-related deaths due to therapy resistance and metastasis. Understanding the mechanism underlying colorectal carcinogenesis is essential for the diagnosis and treatment of CRC. microRNAs (miRNAs) can act as either oncogenes or tumor suppressors in many cancers. A tumor suppressor role for miR-27b has recently been reported in neuroblastoma, while no information about miR-27b in CRC is available. In this study, we demonstrated that miR-27b expression is decreased in most CRC tissues and determined that overexpression of miR-27b represses CRC cell proliferation, colony formation and tumor growth in vitro and in vivo. We identified vascular endothelial growth factor C (VEGFC) as a novel target gene of miR-27b and determined that miR-27b functioned as an inhibitor of tumor progression and angiogenesis through targeting VEGFC in CRC. We further determined that DNA hypermethylation of miR-27b CpG islands decreases miR-27b expression. In summary, an anti-tumor role for miR-27b and its novel target VEGFC in vivo could lead to tumor necrosis and provide a rationale for developing miR-27b as a therapeutic agent.     

Insulin-like growth factor 1 ameliorates pre-eclampsia by inhibiting zinc finger E-box binding homeobox 1 by up-regulation of microRNA-183

As a common hypertensive complication of pregnancy, preeclampsia (PE) remains one of the leading causes of maternal and fetal with high morbidity and mortality worldwide. Much research has identified the vital functions of insulin-like growth factor 1 (IGF-1) in PE treatment. However, the combined roles and molecular mechanism of IGF-1 and microRNAs (miRNAs) underlying PE remain unclear. Therefore, we first measured the expression of IGF-1, zinc finger E-box binding homeobox 1 (ZEB1) and microRNA-183 (miR-183) expression in the placenta tissues of patients with PE by Western blot analysis and RT-qPCR. Interactions among IGF-1, ZEB1 and miR-183 were assessed by Western blot analysis, ChIP-PCR and dual-luciferase reporter gene assay. The effect of IGF-1 on the biological characteristics of trophoblast cells was investigated by CCK-8, colony formation assay and in vitro angiogenesis experiments after cells were transfected with si-IGF-1. Finally, a mouse eclampsia model induced by knockdown of IGF-1 was established to confirm the in vitro effect of IGF-1 on PE. We found that IGF-1, ZEB1 and miR-183 were highly expressed in the placental tissues of patients with PE. The knockdown of IGF-1 resulted in reduced proliferation and invasion of trophoblast cells and was accompanied by inhibited angiogenesis. ZEB1 was positively regulated by IGF-1 via ERK/MAPK pathway, which in turn inhibited miR-153 expression by binding to the miR-183 promoter. The in vitro experiments further confirmed that IGF-1 knockdown could induce PE. To sum up, IGF-1 knockdown elevated expression of miR-183 by downregulating ZEB1, thereby promoting deterioration of PE.     

VEGF和SDF-1 的协同作用对内皮祖细胞增殖与迁移的影响

目的:研究血管内皮生长因子(VEGF)和基质衍生因子-1(SDF-1)的协同作用对高血压脑出血患者内皮祖细胞(EPCs)增殖迁移能力的影响。方法:采集急性期高血压脑出血患者与健康对照的外周静脉血,分离培养外周血中的EPCs。用分别含有不同VEGF与SDF-1的培养基处理患者外周血分离的EPCs,Western blot检测各组细胞以及患者和对照中VEGF和SDF-1的蛋白表达。MTT法检测细胞增值能力,Transwell法检测细胞迁移能力,分别转染VEGF-si RNA与SDF-1-si RNA至各组细胞观察抑制VEGF和SDF-1对EPCs增殖迁移能力的影响。结果:VEGF和SDF-1在患者中的表达显著高于健康对照组。VEGF和SDF-1对EPCs的增殖和迁移能力有促进作用,且在其协同作用下效果显著。抑制VEGF或SDF-1显著降低VEGF和SDF-1对EPCs增殖迁移能力的促进作用。结论:VEGF和SDF-1的协同作可促进急性期高血压脑出血患者EPCs的细胞增殖能力和迁移能力,对患者血管修复提供新的治疗方向。     

Endothelial Lineage Differentiation from Induced Pluripotent Stem Cells Is Regulated by MicroRNA-21 and Transforming Growth Factor β2 (TGF-β2) Pathways

Finding a suitable cell source for endothelial cells (ECs) for cardiovascular regeneration is a challenging issue for regenerative medicine. In this paper, we describe a novel mechanism regulating induced pluripotent stem cells (iPSC) differentiation into ECs, with a particular focus on miRNAs and their targets. We first established a protocol using collagen IV and VEGF to drive the functional differentiation of iPSCs into ECs and compared the miRNA signature of differentiated and undifferentiated cells. Among the miRNAs overrepresented in differentiated cells, we focused on microRNA-21 (miR-21) and studied its role in iPSC differentiation. Overexpression of miR-21 in predifferentiated iPSCs induced EC marker up-regulation and in vitro and in vivo capillary formation; accordingly, inhibition of miR-21 produced the opposite effects. Importantly, miR-21 overexpression increased TGF-β2 mRNA and secreted protein level, consistent with the strong up-regulation of TGF-β2 during iPSC differentiation. Indeed, treatment of iPSCs with TGFβ-2 induced EC marker expression and in vitro tube formation. Inhibition of SMAD3, a downstream effector of TGFβ-2, strongly decreased VE-cadherin expression. Furthermore, TGFβ-2 neutralization and knockdown inhibited miR-21-induced EC marker expression. Finally, we confirmed the PTEN/Akt pathway as a direct target of miR-21, and we showed that PTEN knockdown is required for miR-21-mediated endothelial differentiation. In conclusion, we elucidated a novel signaling pathway that promotes the differentiation of iPSC into functional ECs suitable for regenerative medicine applications.     

MiR-223 suppresses cell proliferation by targeting IGF-1R

To study the roles of microRNA-223 (miR-223) in regulation of cell growth, we established a miR-223 over-expression model in HeLa cells infected with miR-223 by Lentivirus pLL3.7 system. We observed in this model that miR-223 significantly suppressed the proliferation, growth rate, colony formation of HeLa cells in vitro, and in vivo tumorigenicity or tumor formation in nude mice. To investigate the mechanisms involved, we scanned and examined the potential and putative target molecules of miR-223 by informatics, quantitative PCR and Western blot, and found that insulin-like growth factor-1 receptor (IGF-1R) was the functional target of miR-223 inhibition of cell proliferation. Targeting IGF-1R by miR-223 was not only seen in HeLa cells, but also in leukemia and hepatoma cells. The downstream pathway, Akt/mTOR/p70S6K, to which the signal was mediated by IGF-1R, was inhibited as well. The relative luciferase activity of the reporter containing wild-type 3'UTR(3'untranslated region) of IGF-1R was significantly suppressed, but the mutant not. Silence of IGF-1R expression by vector-based short hairpin RNA resulted in the similar inhibition with miR-223. Contrarily, rescued IGF-1R expression in the cells that over-expressed miR-223, reversed the inhibition caused by miR-223 via introducing IGF-1R cDNA that didn't contain the 3'UTR. Meanwhile, we also noted that miR-223 targeted Rasa1, but the downstream molecules mediated by Rasa1 was neither targeted nor regulated. Therefore we believed that IGF-1R was the functional target for miR-223 suppression of cell proliferation and its downstream PI3K/Akt/mTOR/p70S6K pathway suppressed by miR-223 was by targeting IGF-1R.     

Combined Effect of Insulin-Like Growth Factor-1 and CC Chemokine Ligand 2 on Angiogenic Events in Endothelial Cells

Therapeutic angiogenesis may be applied in medical conditions to promote stimulation of angiogenesis. Angiogenesis is a multistep process, which includes endothelial cell proliferation, migration, and tube formation, which is mediated by various angiogenic polypeptides. Thus, studies that elucidate the cellular mechanisms involved in these processes are necessary to develop novel therapeutic strategies. This study investigated the in vitro effects of the pro-angiogenic factors, insulin-like growth factor-1 (IGF-1) and/or chemokine (CC motif) ligand 2 (CCL2), on endothelial cells. Flow cytometry analysis showed that IGF-1 and CCL2 treatment did not interfere with IGF-1 receptor (IGF-1R) expression, but CCL2 treatment increased CCL2 receptor (CCR2) expression. Immunofluorescence analysis revealed that the IGF-1/CCL2 combination induced a greater increase in fibronectin deposition, but the treatments did not alter the expression of the fibronectin receptors, CD49e and CD44. The interaction of fibronectin with cytokines demonstrated that IGF-1/CCL2 promoted changes in intermediate F-actin remodeling that may result in increased endothelial cell adhesion and cell migration mediated by fibronectin. Furthermore, IGF-1/CCL2 stimulated endothelial cells, grown on fibronectin, to form capillary-like structures and intercellular lumina with greater luminal area. These data suggest that IGF-1/CCL2 combination and a fibronectin matrix may contribute to the angiogenesis process to stimulate adhesion, migration, and tube formation by endothelial cells as a result of F-actin remodeling.     

Picropodophyllin inhibits tumor growth of human nasopharyngeal carcinoma in a mouse model

Insulin-like growth factor-1 receptor (IGF-1R) is a cell membrane receptor with tyrosine kinase activity and plays important roles in cell transformation, tumor growth, tumor invasion, and metastasis. Picropodophyllin (PPP) is a selective IGF-1R inhibitor and shows promising antitumor effects for several human cancers. However, its antitumor effects in nasopharyngeal carcinoma (NPC) remain unclear. The purpose of this study is to investigate the antitumor activity of PPP in NPC using in vitro cell culture and in vivo animal model. We found that PPP dose-dependently decreased the IGF-induced phosphorylation and activity of IGF-1R and consequently reduced the phosphorylation of Akt, one downstream target of IGF-1R. In addition, PPP inhibited NPC cell proliferation in vitro. The half maximal inhibitory concentration (IC50) of PPP for NPC cell line CNE-2 was ?1 μM at 24 h after treatment and ?0.5 μM at 48 h after treatment, respectively. Moreover, administration of PPP by intraperitoneal injection significantly suppressed the tumor growth of xenografted NPC in nude mice. Taken together, these results suggest targeting IGF-1R by PPP may represent a new strategy for treatment of NPCs with positive IGF-1R expression.