Epithelial-mesenchymal Transition In Glioblastoma Research Articles

Anti-Vimentin Nanobody Decreases Glioblastoma Cell Invasion In Vitro and In Vivo.

Glioblastoma (GBM) is the most common primary brain tumour and one of the deadliest cancers. In addition to late diagnosis and inadequate treatment, the extremely low survival rate is also due to the lack of appropriate therapeutic biomarkers and corresponding therapeutic agents. One of the potential therapeutic biomarkers is the intermediate filament vimentin, which is associated with epithelial-mesenchymal transition (EMT). The purpose of this study was to analyse the effect of the anti-vimentin nanobody Nb79 on cell invasion in vitro and in vivo. To further our understanding of the mechanism of action, we investigated the association between Nb79 and EMT in GBM and GBM stem cells by analysing the expression levels of key EMT-related proteins. The expression of vimentin in glioma tissues and cells was determined by RT-qPCR. An invasion assay was performed on differentiated glioblastoma cell line U-87 MG and stem cell line NCH421k in vitro as well as in vivo in zebrafish embryos. The effect of Nb79 on expression of EMT biomarkers beta-catenin, vimentin, ZEB-1 and ZO1 was determined by Western blot and immunocytochemistry. Our study shows that vimentin is upregulated in glioblastoma tissue compared to lower grade glioma and non-tumour brain tissue. We demonstrated that treatment with Nb79 reduced glioblastoma cell invasion by up to 64% in vitro and up to 21% in vivo. In addition, we found that the tight junction protein ZO-1 had higher expression on the cell membrane, when treated with inhibitory anti-vimentin Nb79 compared to control. In conclusion, our results suggest that anti-vimentin nanobody Nb79 is a promising tool to target glioblastoma cell invasion.

Effect of PACAP on Hypoxia-Induced Angiogenesis and Epithelial-Mesenchymal Transition in Glioblastoma.

Pituitary adenylate cyclase-activating polypeptide (PACAP) exerts different effects in various human cancer. In glioblastoma (GBM), PACAP has been shown to interfere with the hypoxic micro-environment through the modulation of hypoxia-inducible factors via PI3K/AKT and MAPK/ERK pathways inhibition. Considering that hypoxic tumor micro-environment is strictly linked to angiogenesis and Epithelial–Mesenchymal transition (EMT), in the present study, we have investigated the ability of PACAP to regulate these events. Results have demonstrated that PACAP and its related receptor, PAC1R, are expressed in hypoxic area of human GBM colocalizing either in epithelial or mesenchymal cells. By using an in vitro model of GBM cells, we have observed that PACAP interferes with hypoxic/angiogenic pathway by reducing vascular-endothelial growth factor (VEGF) release and inhibiting formation of vessel-like structures in H5V endothelial cells cultured with GBM-conditioned medium. Moreover, PACAP treatment decreased the expression of mesenchymal markers such as vimentin, matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9) as well as CD44 in GBM cells by affecting their invasiveness. In conclusion, our study provides new insights regarding the multimodal role of PACAP in GBM malignancy.

The EIF4A3/CASC2/RORA Feedback Loop Regulates the Aggressive Phenotype in Glioblastomas

Glioblastoma (GBM) is a common and refractory subtype of high-grade glioma with a poor prognosis. The epithelial-mesenchymal transition (EMT) is an important cause of enhanced glioblastoma invasiveness and tumor recurrence. Our previous study found that retinoic acid receptor-related orphan receptor A (RORA) is a nuclear receptor and plays an important role in inhibiting proliferation and tumorigenesis of glioma. We further confirmed RORA was downregulated in GBM. Thus, we determined whether RORA was involved in the migration, invasion, and EMT of GBM. Human GBM cell lines, U87 and T98G, and patient-derived glioma stem cells (GSCs), GSC2C and GSC4D, were used for in vitro and in vivo experiments. The expressions of RORA, CASC2, and EIF4A3 in GBM cells and GSCs were detected by RT-qPCR and western blotting. The biological effects of RORA, CASC2, and EIF4A3 on GBM migration, invasion, and EMT were evaluated using the migration assay, transwell assay, immunofluorescence staining, and xenograft experiments. We found that RORA inhibited the migration, invasion, and EMT of GBM. CASC2 could bind to, maintain the stability, and promote the nuclear translocation of RORA protein. EIF4A3 could downregulate CASC2 expression via inducing its cleavage, while RORA transcriptionally inhibited EIF4A3 expression, which formed a feedback loop among EIF4A3/CASC2/RORA. Moreover, gene set enrichment analysis (GSEA) and in vitro and in vivo experiments showed RORA inhibited the aggressiveness of GBM by negatively regulating the TGF-β1/Smad signaling pathway. Therefore, The EIF4A3/CASC2/RORA feedback loop regulated TGF-β1/Smad signaling pathway might become a promising therapeutic strategy for GBM treatment.

Long Noncoding RNA LINC-PINT Suppresses Cell Proliferation, Invasion, and EMT by Blocking Wnt/β-Catenin Signaling in Glioblastoma.

Background: Glioblastoma (GBM) represents the most aggressive glioma with high invasive potential. Recent studies proved the involvement of epithelial-mesenchymal transition (EMT) process in increasing the malignancy and invasiveness of GBM. LncRNAs have been verified to play pivotal roles in human disease including GBM. However, the molecular mechanisms of lncRNA-mediated EMT in GBM remain largely unknown. LINC-PINT, a LncRNA which has never been studied in GBM before, was predicted to be negatively associated with EMT in GBM. This study aimed to explore the biological function and the EMT relevance of LINC-PINT in GBM and further explore the molecular mechanism. Methods: The bioinformatic prediction data of LINC-PINT in GBM was derived from The Cancer Genome Atlas (TCGA) database by R software and GEPIA website. qRT-PCR assay was performed to detect the expression level of LINC-PINT in GBM cell lines. Cell counting kit-8 (CCK8), clone formation, transwell, and wound healing assays were performed to determine the biological function of LINC-PINT in vivo. Tumor xenograft experiment and tumor peritoneal metastasis experiments were performed to verify the in vivo function. Western blot and immunofluorescence staining assays were carried out to detect the relevance of LINC-PINT with EMT and Wnt/β-catenin signaling. Rescue assays were performed to check the regulation mechanism of LINC-PINT/Wnt signaling/EMT axis in GBM. Results: LINC-PINT was downregulated in GBM cell lines. LINC-PINT suppressed cell progression, invasion, and EMT in GBM. LINC-PINT blocked Wnt/β-catenin signaling in GBM. Conclusion: LINC-PINT suppressed cell proliferation, invasion, and EMT by blocking Wnt/β-catenin signaling in GBM.

NOX4-Derived ROS Mediates TGF-β1-Induced Metabolic Reprogramming during Epithelial-Mesenchymal Transition through the PI3K/AKT/HIF-1α Pathway in Glioblastoma.

Current studies on tumor progression focus on the roles of cytokines in the tumor microenvironment (TME), and recent research shows that transforming growth factor-β1 (TGF-β1) released from TME plays a pivotal role in tumor development and malignant transformation. The alteration in cellular metabolism is a hallmark of cancer, which not only provides cancer cells with ATP for fuel cellular reactions, but also generates metabolic intermediates for the synthesis of essential cellular ingredients, to support cell proliferation, migration, and invasion. Interestingly, we found a distinct metabolic change during TGF-β1-induced epithelial-mesenchymal transition (EMT) in glioblastoma cells. Indeed, TGF-β1 participates in metabolic reprogramming, and the molecular basis is still not well understood. NADPH oxidases 4 (NOX4), a member of the Nox family, also plays a key role in the biological effects of glioblastoma. However, the relationship between NOX4, TGF-β1, and cellular metabolic changes during EMT in glioblastoma remains obscure. Here, our findings demonstrated that TGF-β1 upregulated NOX4 expression accompanied by reactive oxygen species (ROS) through Smad-dependent signaling and then induced hypoxia-inducible factor 1α (HIF-1α) overexpression and nuclear accumulation resulting in metabolic reprogramming and promoting EMT. Besides, inhibition of glycolysis reversed EMT suggesting a causal relationship between TGF-β1-induced metabolic changes and tumorigenesis. Moreover, TGF-β1-induced metabolic reprogramming and EMT which modulated by NOX4/ROS were blocked when the phosphoinositide3-kinase (PI3K)/AKT/HIF-1α signaling pathways were inhibited. In conclusion, these suggest that NOX4/ROS induction by TGF-β1 can be one of the main mechanisms mediating the metabolic reprogramming during EMT of glioblastoma cells and provide promising strategies for cancer therapy.

MicroRNA-381 inhibits metastasis and epithelial-mesenchymal transition of glioblastoma cells through targeting LEF1.

Glioblastoma is a common intracranial malignancy that is extremely harmful to human life and health. Various microRNAs (miRNAs) have been reported to be involved in the progression of glioblastoma, except miR-381. Therefore, the purpose of this study is to investigate the role of miR-381 in glioblastoma. The expression of miR-381 and LEF1 (lymphoid enhancer-binding factor-1) was quantified using quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) and Western blot analysis. Transwell and Dual-Luciferase reporter assays were used to investigate the regulatory mechanism of miR-381/LEF1 in glioblastoma. Downregulation of miR-381 was observed in A172 cells. In addition, the overexpression of miR-381 restrained migration and invasion of glioblastoma cells. Furthermore, overexpression of miR-381 inhibited epithelial-mesenchymal transition (EMT) in A172 cells. Further, miR-381 was confirmed to directly target LEF1 and negatively regulates its expression in glioblastoma cells. Downregulation of LEF1 also inhibited cell migration, invasion, and EMT in glioblastoma cells. More importantly, the upregulation of LEF1 abolished the inhibitory effect of miR-381 in glioblastoma cells. MiR-381 inhibits cell metastasis and EMT in glioblastoma by suppressing LEF1 expression.

Insulin-like growth factor II mRNA-binding protein 3 promotes cell proliferation, migration and invasion in human glioblastoma.

Background/Aims: Recently, the insulin-like growth factor mRNA-binding protein 3 (IMP3) has been reported to be involved in tumorigenesis. We aimed to study the expression and role of IMP3 in human glioblastoma.Methods: We analyzed the expression of IMP3 in 70 cases of glioma tissues, normal brain tissues and 5 kinds of cell lines using western blot. Immunohistochemistry (IHC) was used to evaluate the expression and distribution of IMP3 in glioma tissues. Colony formation, wound healing, migration and invasion assays and tumorigenesis in nude mice were used to explore the function of IMP3 in vitro and in vivo. The epithelial-mesenchymal transition (EMT)-related biomarkers were detected by western blot.Results: We found that the expression level of IMP3 was obviously higher in glioma tissues than that in normal brain tissues, and associated with glioma grade. In-vitro assays revealed that IMP3 overexpression significantly induced cell proliferation, migration, and invasion. Mechanically, IMP3 over-expression downregulated the expression of E-cadherin, but upregulated the expressions of N-cadherin, vimentin, snail, slug and MMP9. However, the inhibition of IMP3 impaired these oncogenic effects. In vivo assay also demonstrated that silencing of IMP3 inhibited tumor growth and improved survival of tumor-bearing xenograft nude mice.Conclusion: IMP3 can promote cell proliferation, migration and invasion by inducing EMT in glioblastoma. Thus, targeting IMP3 pathway may be a novel way to treat patients with glioblastoma.

Resveratrol Suppresses Epithelial-Mesenchymal Transition in GBM by Regulating Smad-Dependent Signaling.

Glioblastoma (GBM) is the most common and malignant intracranial tumor in adults. Despite continuous improvements in diagnosis and therapeutic method, the prognosis is still far away from expectations. The invasive phenotype of GBM is the main reason for the poor prognosis. Epithelial-mesenchymal transition (EMT) is recognized as a participator in this invasive phenotype. Resveratrol, a natural plant-derived compound, is reported to be able to regulate EMT. In the present study, we used TGF-β1 to induce EMT and aimed to evaluate the effect of resveratrol on EMT and to explore the underline mechanism in GBM. Western blotting was used to detect the expression of EMT-related markers, stemness markers, and Smad-dependent signaling. Wound healing assay and transwell invasion assay were performed to evaluate the migratory and invasive ability of GBM cells. Gliosphere formation assay was used to investigate the effect of resveratrol on the ability of self-renewal. Xenograft experiment was conducted to examine the effect of resveratrol on EMT and Smad-dependent signaling in vivo. Our data validated that resveratrol suppressed EMT and EMT-associated migratory and invasive ability via Smad-dependent signaling in GBM cells. We also confirmed that resveratrol obviously inhibited EMT-induced self-renewal ability of glioma stem cells (GSCs) and inhibited EMT-induced cancer stem cell markers Bmi1 and Sox2, suggesting that resveratrol is able to suppress EMT-generated stem cell-like properties in GBM cells. Furthermore, we also showed the inhibitory effect of resveratrol on EMT in xenograft experiments in vivo. Overall, our study reveals that resveratrol suppresses EMT and EMT-generated stem cell-like properties in GBM by regulating Smad-dependent signaling and provides experimental evidence of resveratrol for GBM treatment.

Time Sequential Changes of Epithelial-Mesenchymal Transition Signaling Induced by Ionizing Radiation using Next-Generation Sequencing in Glioblastoma

Epithelial-mesenchymal transition (EMT) is considered as one of the mechanisms of treatment resistance in glioblastoma. We evaluated a time sequential changes of EMT signaling in glioblastoma induced by ionizing radiation. The cell line U-373 MG (human glioblastoma) was irradiated with 6Gy of high energy X-ray (6MV) with dose rate of 6 Gy/min. Next generation sequencing (NGS) was performed on the cell line before irradiation (baseline), 6 hours, 24 hours, and 48 hours after irradiation and database of essential genes (DEG) was evaluated in each period. The DEGs were compared with those included in the 128 of the GeneSets. P value from the Fisher exact test and Q value from the Benjamini Hochberg methods were calculated. All KEGG map pathways were evaluated and the EMT related KEGG pathways were assessed using the EMT gene database (dbEMT). GeneSet analysis showed that ionizing radiation up-regulated the expression of the GeneSet of the wholemark of EMT at 6 hours and 24 hours after irradiation. On KEGG pathway analysis, extracellular matrix (ECM) receptor interactions increased over time and the expression of miRNA-21 increased at 6, 24, and 48 hours after irradiation resulting in cell growth and survival pathway. Increased RTK expression suggested RTK-induced EMT process. HIF-α induced hypoxia and activated TGF-β signaling pathway, which is related with EMT. TGF- β activated Smad2/3 followed by activation of Smad4. Ionizing radiation may promote EMT in glioblastoma, resulting in treatment related resistance. miRNA-21 may play a critical role in EMT after irradiation. EMT blocking to prevent treatment resistance may be a promising strategy to increase survival in glioblastoma.

S100A4 Is a Biomarker and Regulator of Glioma Stem Cells That Is Critical for Mesenchymal Transition in Glioblastoma.

Glioma stem cells (GSC) and epithelial-mesenchymal transition (EMT) are strongly associated with therapy resistance and tumor recurrence, but the underlying mechanisms are incompletely understood. Here, we show that S100A4 is a novel biomarker of GSCs. S100A4+ cells in gliomas are enriched with cancer cells that have tumor-initiating and sphere-forming abilities, with the majority located in perivascular niches where GSCs are found. Selective ablation of S100A4-expressing cells was sufficient to block tumor growth in vitro and in vivo We also identified S100A4 as a critical regulator of GSC self-renewal in mouse and patient-derived glioma tumorspheres. In contrast with previous reports of S100A4 as a reporter of EMT, we discovered that S100A4 is an upstream regulator of the master EMT regulators SNAIL2 and ZEB along with other mesenchymal transition regulators in glioblastoma. Overall, our results establish S100A4 as a central node in a molecular network that controls stemness and EMT in glioblastoma, suggesting S100A4 as a candidate therapeutic target. Cancer Res; 77(19); 5360-73. ©2017 AACR.

Inhibition of Bevacizumab-induced Epithelial-Mesenchymal Transition by BATF2 Overexpression Involves the Suppression of Wnt/β-Catenin Signaling in Glioblastoma Cells.

Bevacizumab (BV) has been used for the treatment of recurrent glioblastoma. However, it also induces epithelial-mesenchymal transition (EMT) in glioblastoma cells, which compromises its efficacy. BATF2 (basic leucine zipper ATF-like transcription factor 2), a multi-target transcriptional repressor, has been found to suppress cancer development partly through inhibition of Wnt/β-catenin singling. The roles of BATF2 and Wnt/β-catenin signaling in BV-induced EMT in glioblastoma cells were investigated in this study. BV was used to treat U87MG cells, and TOP/FOP FLASH luciferase reporters were employed to determine the activity of Wnt/β-catenin signaling. EMT markers were detected with quantitative reverse transcription-PCR and western blotting. Immunofluorescence (IF) was used to determine the compartmentation of β-catenin. Wound-healing, TransWell and ECIS assays were used to analyze cell adhesion, invasion and migration. BV induced EMT phenotype in U87MG cells, and BATF2 overexpression significantly inhibited BV-induced EMT with suppression of Wnt/β-catenin signaling. Our findings expanded the understanding of the role of BATF2 in tumors, and also suggested a potential of using BATF2 as a therapeutic target to hinder bevacizumab induced EMT in glioblastoma.

WITHDRAWN: MiR-143 suppresses the epithelial-mesenchymal transition of spinal glioblastoma through down-regulation of ERK5

Abstract The spinal glioblastoma (GBM) represents the one of most common tumors in humans. However, the biological processes and molecular mechanisms of spinal GBM are still unclear. It is known that miR-143 participates in the development of various tumor progressions. The present study was to evaluate the level of miR-143 in spinal GBM tissues and cells. We further investigated that the molecular mechanisms of miR-143 in U87 and U251 cell lines. Here, our data showed that the expression levels of miR-143 were significantly reduced in spinal GBM tissues and cell lines. Accordingly, the expression levels of the extracellular signal regulated kinase 5 (ERK5) were significantly increased in spinal GBM tissues and cell lines. Ectopic expression of miR-143 in U87 and U251 cells resulted in decreased cell growth and enhanced cell apoptosis, and inhibited the expression of epithelial-mesenchymal transition (EMT) biomarkers. Further study characterized the 3' untranslated region (3'-UTR) of ERK5 gene as a direct target of miR-143 in U87 and U251 cells as determined by luciferase reporter assays. In addition, the ectopic expression of miR-143 led to the down-regulation of epidermal growth factor receptor (EGFR), while the over-expression of ERK5 reversed the miR-143-inhibited EGFR expression, and promoted cell growth and the expression of EMT biomarkers. In conclusion, this study demonstrated that miR-143 plays a crucial role in regulating the EMT of GBM by directly targeting ERK5, and miR-143 may act as a potential therapeutic target in spinal GBM patients.

The involvement of anterior gradient 2 in the stromal cell-derived factor 1-induced epithelial-mesenchymal transition of glioblastoma.

In recent years, it has been widely identified that the stromal cell-derived factor 1 (SDF-1) and anterior gradient 2 (AGR2) were implicated in the development of epithelial-mesenchymal transition (EMT) in a variety of cancers. However, the involvement of SDF-1-AGR2 pathway in the EMT of glioblastoma has not been investigated. In the present study, the in vitro assays were used to investigate the role of AGR2 in cell cycle, migration, and invasion. We found that the expressions of AGR2 and chemokine (C-X-C motif) receptor 4 (CXCR4) were obviously upregulated in glioblastoma cells T98G, A172, U87, and U251 than those in normal human astrocytes (NHA) (all p < 0.01), among which both U87 and U251 cells presented the highest expression (p > 0.05). Western blot revealed that SDF-1 induced the expression of p-AKT, AGR2, and EMT markers (N-cadherin, matrix metalloproteinase-2 (MMP2), and Slug) in a dose-dependent manner in U87 and U251 cells. However, the depletion of AGR2 reversed SDF-1-induced upregulation of EMT markers rather than p-AKT. Furthermore, functional analysis identified that knockdown of AGR2 induced cell cycle arrest in G0/G1 phase and suppressed the migration and invasion of U87 and U251 cells. Taken together, SDF-1-CXCR4 pathway induced the expression of AGR2 to control the progression of EMT likely via AKT pathway in the development of glioblastoma. Our findings lay a promising foundation for the SDF-1-AGR2 axis-targeting therapy in patients with glioblastoma.