Target For Glioma Therapy Research Articles

MicroRNA-370-3p inhibits human glioma cell proliferation and induces cell cycle arrest by directly targeting β-catenin

ObjectiveThe aim of this study was to explore the expression and biological role of miR-370-3p in human gliomas. MethodsClinical specimens from the brains of 20 glioma patients and 10 healthy controls were obtained to quantify the expression level of miR-370-3p using quantitative real-time PCR. Oligonucleotide mimics of miR-370-3p were transfected into U251 and U87-MG cells for a gain of function assay. The CCK-8 assay, colony formation assay, EdU assay and flow cytometry were used to evaluate the roles of miR-370-3p in cell proliferation and the cell cycle regulation. Western blot and luciferase activity assays were used to investigate the reciprocal relationship between miR-370-3p and its predicted target, β-catenin. ResultsmiR-370-3p expression was frequently found to be decreased in glioma tissues, and its expression level was negatively correlated with the malignant degree of the glioma. Overexpression of miR-370-3p showed a significant inhibitory effect on cell proliferation and accompanied cell cycle G0/G1 arrest in U251 and U87-MG cells. Furthermore, miR-370-3p inhibited the expression of the canonical Wnt pathway downstream targets cyclin D1 and c-myc via direct binding interaction with the 3′-untranslated region of β-catenin mRNA. Reintroduction of β-catenin could partially reverse the anti-proliferation effect of miR-370-3p. Finally, in 20 glioma tissues the expression of miR-370-3p was negatively correlated with both protein and mRNA levels of β-catenin. ConclusionmiR-370-3p suppresses glioma cell growth by directly targeting β-catenin, suggesting that the miR-370-3p/β-catenin axis may be a target for glioma therapy.

Inhibiting receptor tyrosine kinase AXL with small molecule inhibitor BMS-777607 reduces glioblastoma growth, migration, and invasion in vitro and in vivo.

PurposeReceptor tyrosine kinase AXL (RTK-AXL) is regarded as suitable target in glioma therapy. Here we evaluate the anti-tumoral effect of small molecule inhibitor BMS-777607 targeting RTK-AXL in a preclinical glioma model and provide evidence that RTK-AXL is expressed and phosphorylated in primary and recurrent glioblastoma multiforme (GBM).Experimental designWe studied the impact of BMS-777607 targeting RTK-AXL in GBM models in vitro and in vivo utilizing glioma cells SF126 and U118MG. Impact on proliferation, apoptosis and angiogenesis was investigated by immunohistochemistry (IHC) and functional assays in vitro and in vivo. Tumor growth was assessed with MRI. Human GBM tissue was analyzed in terms of RTK-AXL phosphorylation by immunoprecipitation and immunohistochemistry.ResultsBMS-777607 displayed various anti-cancer effects dependent on increased apoptosis, decreased proliferation and migration in vitro and ex vivo in SF126 and U118 GBM cells. In vivo we observed a 56% tumor volume reduction in SF126 xenografts and remission in U118MG xenografts of more than 91%. The tube formation assay confirmed the anti-angiogenic effect of BMS-777607, which became also apparent in tumor xenografts. IHC of human GBM tissue localized phosphorylated RTK-AXL in hypercellular tumor regions, the migratory front of tumor cells in pseudo-palisades, and in vascular proliferates within the tumor. We further proved RTK-AXL phosphorylation in primary and recurrent disease state.ConclusionCollectively, these data strongly suggest that targeting RTK-AXL with BMS-777607 could represent a novel and potent regimen for the treatment of primary and recurrent GBM.

Peptide-mediated drug delivery systems for targeted glioma therapy

Peptide-mediated drug delivery systems for targeted glioma therapy

Glioma-targeted therapy using Cilengitide nanoparticles combined with UTMD enhanced delivery

Malignant gliomas especially glioblastoma (GBM) are poorly responsive to the current treatments. Cilengitide (CGT) is a cyclic pentapeptide that demonstrated efficacy for GBM treatment by targeting the integrins avβ3 and avβ5 over-expressed on GBM cells. However, clinical translation of this therapy has been limited by issues including fast blood clearance, high kidney and liver uptake, poor blood–brain barrier (BBB) penetration, low tumor specificity and rapid washout from tumors. In this study, these issues were tackled in an integrated manner using a multi-stage strategy combining ultrasound-targeted microbubble destruction (UTMD) with CGT nanotherapy. CGT nanoparticles (CGT-NP) prepared using gelatin and Poloxamer 188-grafted heparin copolymer demonstrated significant apoptotic and cytotoxic effects in C6 GBM cells. Biodistribution study in a rat GBM model demonstrated buildup of high CGT level in tumors subjected to CGT-NP+UTMD combined therapy. The tumor CGT level in these animals was increased over 3-fold, tumor retention of CGT prolonged and renal clearance significantly reduced when compared with free CGT with or without UTMD. CGT-NP+UTMD treatment was further shown to extend the median survival period from less than 20days in the control and about 30days in free CGT group to about 80days. This was achieved with low CGT dosing level (2mg/kg twice weekly). In situ monitoring of GFAP, Ki67, caspase-3, Beclin-1, and LC-3 in the tumor samples together with TUNEL assay, transmission electron microscope imaging and Western blot assay all demonstrated high apoptotic and autophagy activities induced by the combined therapy. In conclusion, this study has provided extensive preclinical data supporting the use of this combined therapy to overcome the limitations of standard CGT treatment of gliomas.

Receptor-Mediated Drug Delivery Systems Targeting to Glioma.

Glioma has been considered to be the most frequent primary tumor within the central nervous system (CNS). The complexity of glioma, especially the existence of the blood-brain barrier (BBB), makes the survival and prognosis of glioma remain poor even after a standard treatment based on surgery, radiotherapy, and chemotherapy. This provides a rationale for the development of some novel therapeutic strategies. Among them, receptor-mediated drug delivery is a specific pattern taking advantage of differential expression of receptors between tumors and normal tissues. The strategy can actively transport drugs, such as small molecular drugs, gene medicines, and therapeutic proteins to glioma while minimizing adverse reactions. This review will summarize recent progress on receptor-mediated drug delivery systems targeting to glioma, and conclude the challenges and prospects of receptor-mediated glioma-targeted therapy for future applications.

WITHDRAWN: Using FUS induced BBB/BTB-opening technique combined with Doxorubicin liposomes to improve glioma-targeted inhibition

// Ying-Zheng Zhao 1, 2, 3 , Li-Juan Chen 4 , Qian Lin 1 , Jun Cai 5 , Wen-Ze Yu 1 , Ya-Ping Zhao 2 , Chong-Yong Xu 2 , Kai-Li Mao 1 , Fu-Rong Tian 1 , Wen-Feng Li 6 , Ho Lun Wong 7 , Cui-Tao Lu 1, 2 1 College of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang Province 325035, China 2 The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province 325000, China 3 Hainan Medical College, Haikou City, Hainan Province 570102, China 4 Dispensary of Traditional Chinese Medicine, Wenzhou Central Hospital, Wenzhou, Zhejiang Province 325000, China 5 Departments of Pediatrics and Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA 6 The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province 325000, China 7 School of Pharmacy, Temple University, Philadelphia, Pennsylvania 19140, USA Correspondence to: Ho Lun Wong, e-mail: ho-lun.wong@temple.edu Cui-Tao Lu, e-mail: lctuua@sina.com Keywords: chemotherapy, focused ultrasound, nanotechonology, BBB opening, glioma Received: July 09, 2015 Accepted: August 20, 2015 Published: September 02, 2015 ABSTRACT Purpose: Blood-brain barrier and blood-tumor barrier (BBB/BTB) are the main limitations for chemotherapeutics in glioma therapy. Focused ultrasound (FUS) combined novel Doxorubicin-loaded liposomes (LIP-DOX) was applied to open the BBB/BTB and improve the efficiency of glioma-targeted chemotherapy. Experimental designs: Particle size, Zeta potential and drug encapsulation efficiency were evaluated. C6 glioma model rats were established to evaluate the BBB/BTB disruption and the glioma inhibition in vivo . With Evans Blue (EB) as the model, the permeability of BBB/BTB was evaluated. The glioma inhibition of FUS+LIP-DOX was investigated by magnetic resonance images (MRI) and confocal laser microscope. The activities of β1-intergrin and claudin-5 proteins in response to FUS-mediated BBB/BTB opening were explored. Results: LIP-DOX has suitable nanoscale size and good polydispersity index. From EB extravasation experiment, FUS increased the BBB/BTB penetration and accumulation of EB in the glioma. LIP-DOX combined with FUS could efficiently enhance DOX penetrate into the model rat brains, realizing strong glioma inhibition in vivo . Among DOX-administrated groups, FUS+LIP-DOX group showed the beat inhibition on glioma. FUS+LIP-DOX group reduced the tumor progression ratio from 1.18 to −0.20, extending the median survival from 23d to 57.5d. β1-intergrin and claudin-5 were significantly decreased after FUS treatment, which explained the molecular mechanisms of BBB-opening by FUS. Conclusions: Glioma-targeted inhibition can be realized by using FUS induced BBB/BTB-opening technique combined with LIP-DOX. This combined technology will be developed as a potential strategy for glioma-targeted therapy.

Abstract 4158: Novel PAK4-mediated regulation of endothelial CXCL1/CXCR2 signaling and angiogenesis in glioblastoma

Abstract Increased endothelial cell proliferation and aberrant neovascularization are pathological hallmarks of glioblastoma that correlate with clinical outcome. Recent studies have also implicated ionizing radiation (IR)-induced angiogenesis as a potential cause for tumor recurrence and metastases in several malignancies. Its impact in gliomas has not been characterized. Factors that drive endothelial proliferation, angiogenesis and interaction of endothelial cells with tumor cells in the context of radiotherapy are potentially novel targets for glioma therapy. Our previous studies demonstrated high levels of expression of p21-activated kinase 4 (PAK4) in gliomas; analyses of tumor cell medium (CM) prepared from shRNA-mediated PAK4-knockdown cells using an angiogenesis antibody array showed a significant decrease in key angiogenic factors including CXCL1. Treatment of human brain microvascular endothelial cells (HBMECs) with CM from PAK4-knockdown cells (PAK4-kd CM) significantly inhibited proliferation, migration and microtubule formation compared with CM from control and scrambled vector-expressing glioma cells. PAK4-kd CM treatment also suppressed CXCR2 activation and decreased the expression levels of p-STAT3, VEGF, MMP-2 and cyclinD1 in HBMECs. Additionally, treatment with CM from ionizing radiation (IR, 8 Gy)-treated cells resulted in elevated CXCL1, MMP-2 and VEGF levels in HBMECs, and induced high levels of endothelial capillary network formation on matrigel, indicating an IR-induced angiogenesis in these cells. Conversely, PAK4-kd inhibited IR-induced angiogenesis and decreased p-STAT3, VEGF and MMP-2 levels in IR-treated HBMECS. Further, in vivo experiments with orthotopic intracranial tumors in nude mice showed growth suppression in PAK4-knockdown tumors compared to control tumors. Immunohistochemical analyses of brain tumor sections revealed a significant decrease in CXCL1, VEGF and MMP-2 in PAK4.sh tumors. In summary, our studies emphasize a novel regulation of angiogenic switch and endothelial CXCL1/CXCR2 signaling by PAK4 in tumor cells, thereby, suggests the role of PAK4 as a critical mediator of tumor-endothelial cell interactions in glioblastoma. Abrogation of key angiogenic signaling after IR treatment and inhibition of in vivo tumor growth by PAK4 suppression indicates its therapeutic potential in the treatment of glioma. Citation Format: Divya Kesanakurti, Jihong Xu, Alessandro Canella, Prabhakaran Nagarajan, Balveen Kaur, Vinay K. Puduvalli. Novel PAK4-mediated regulation of endothelial CXCL1/CXCR2 signaling and angiogenesis in glioblastoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4158. doi:10.1158/1538-7445.AM2015-4158

Nrdp1-mediated ErbB3 degradation inhibits glioma cell migration and invasion by reducing cytoplasmic localization of p27(Kip1).

We previously reported that loss of Nrdp1 contributes to human glioma progression by reducing apoptosis. However, the role of Nrdp1 in glioma migration and invasion has not been investigated. Here, we report that ErbB3, a substrate of Nrdp1, is undetectable in normal brain tissues and grade II/III glioma tissues, but is abundant in a certain percentage of grade IV glioma tissues and is associated with the loss of Nrdp1. This suggests that Nrdp1 may be involved in glioma migration and invasion by regulating ErbB3. Thus, the role of Nrdp1/ErbB3 signaling in glioma cell migration and invasion was investigated using Nrdp1 loss- and gain-of-function. The results show that down-regulation of Nrdp1 by use of short hairpin RNA promoted glioma cell migration and invasion. In contrast, overexpression of Nrdp1 significantly inhibited glioma cell migration and invasion. Further investigation on molecular targets revealed that Nrdp1 decreased the level of ErbB3, which resulted in decreasing p-AKT thereby reducing cytoplasmic p27(Kip1). Taken together, these findings suggest that Nrdp1-mediated ErbB3 degradation suppresses glioma migration and invasion and that loss of Nrdp1 may amplify ErbB3 signaling to contribute to glioma migration and invasion. These findings suggest that Nrdp1 may be a target for glioma therapy.

Neurotrophin receptors TrkB and TrkC promote Brain Tumor Initiating Cells growth and are novel targets for glioma therapy. (P4.242)

Neurotrophin receptors TrkB and TrkC promote Brain Tumor Initiating Cells growth and are novel targets for glioma therapy. (P4.242)

Biochanin A inhibits endothelial cell functions and proangiogenic pathways: implications in glioma therapy.

Malignant gliomas, such as glioblastoma multiforme, are highly vascularized tumors of the central nervous system. A rich network of angiogenic vessels supporting glioma growth is an important therapeutic target in glioma therapy. In the past few years, small molecules have gained interest as multitargeting therapies for cancer. Biochanin A is a small, natural dietary isoflavone known for its anticancer potential. Previously, we have found that biochanin A inhibits invasion in human glioblastoma cells. In this study, we elucidated the antiangiogenic mechanisms of biochanin A using rat brain tumor (C6) and murine brain endothelial (bEnd.3) cells and an ex-vivo chick chorioallantoic membrane model. Biochanin A inhibited endothelial cell functions such as cell viability, migration, and invasion, as analyzed using MTT, scratch wound, and gelatin zymography assays. Activation of proangiogenic proteins (ERK/AKT/mTOR) was inhibited. Biochanin A also inhibited chemical hypoxia-inducible factor-1α and vascular endothelial growth factor in C6 cells. Results of chick chorioallantoic membrane assay showed that biochanin A inhibited blood vessel formation ex vivo. As these results suggest that biochanin A directly targets different facets of angiogenesis in vitro and ex vivo, this study provides a rationale for future preclinical evaluation of its efficacy against angiogenic gliomas.

IB-05 * TUMOR-PROCESSED OSTEOPONTIN/SPP1 SHAPES MICROGLIA POLARIZATION AND IMMUNE MICROENVIRONMENT OF GLIOMA

Malignant gliomas attract resident microglia and macrophages and re-program these cells into pro-invasive, immunosuppressive cells. It results in formation of tumor supportive microenvironment and evasion of antitumor responses. The analysis of marker genes in microglia and macrophages infiltrating experimental gliomas indicates different kinetics and functions of various myeloid subpopulations during glioma progression. Signals responsible for recruitment and polarization of tumor infiltrating myeloid cells are poorly known. Proteomic analysis of glioma secretome revealed a presence of osteopontin (SPP1) and lactadherin (MGF-E8) in microglia-activating fractions. Both proteins stimulated microglia via αvβ3 integrin signaling that results in activation of PI-3K/Akt and FAK, enhancement of microglial migration, phagocytosis and transcriptional responses. Inhibition of ligand-integrin interactions with short interfering peptides abolished pro-invasive polarization in glioma-microglia co-cultures. We found that SPP1, highly overexpressed in glioma cells, was specifically processed by sequential thrombin and metalloproteinase-dependent cleavage. This type of processing results in losing SPP1 pro-inflammatory activity leaving intact its pro-tumorigenic activity and does not occur in non-transformed cells. Knockdown of SPP1 in glioma cells strongly reduced growth of intracranial gliomas. The number of infiltrating microglia/macrophages (Iba1+) was not affected, but amoeboid transformation, expression of the alternative phenotype markers and angiogenesis were reduced in SPP1-depleted gliomas. Interestingly, infiltrating Iba1+ cells did not undergo pro-invasive polarization. Moreover, SPP1-depleted tumors were infiltrated with T cytotoxic lymphocytes, while accumulation of T regulatory cells was significantly reduced. The expression of SPP1 is up-regulated in human glioblastoma and inversely correlated with patient's survival. Our findings demonstrate that glioma-derived and specifically processed osteopontin/SPP1 polarizes glioma-infiltrating microglia and contributes to transformation of tumor microenvironment. This defines osteopontin/SPP1 a new biomarker and target for glioma therapy, and shows that targeting glioma-microglia interactions within tumor microenvironment is a promising strategy to fight these tumors. Studies were supported by a grant 2012/04/A/NZ3/00630 from the National Science Center.

Abstract 3338: IGFBP2 promotes EGFR/STAT3 nuclear crosstalk in glioma

Abstract Insulin-like growth factor binding protein 2 (IGFBP2) is a pleiotropic secreted protein that is overexpressed in various cancers including glioma. Extracellular IGFBP2 binds and modulates the activity of insulin growth factors I and II (IGFI and IGFII) while cytoplasmic IGFBP2 interacts with signaling pathways essential for cell proliferation and survival. The versatility of IGFBP2 as a secreted or cytoplasmic signaling effector is widely characterized; however, the functions of nuclear IGFBP2 remain largely unknown. Through genomic and functional analyses of glioma, we mechanistically elucidated the role of nuclear IGFBP2 and discovered a functional interaction of IGFBP2 with epidermal growth factor receptor (EGFR) and signal transducer and activator of transcription 3 (STAT3) proteins. Our findings established a signaling hierarchy of IGFBP2-EGFR-STAT3; IGFBP2 not only upregulates EGFR/STAT3 signaling activity, but also facilitates EGFR nuclear translocation and subsequent nuclear EGFR/STAT3 activity. Furthermore, mutation of the nuclear localization signal of IGFBP2 demonstrated that nuclear translocation of IGFBP2 is critical to promote the nuclear activity of EGFR. By identifying the role of IGFBP2 in perpetuating nuclear crosstalk between EGFR/STAT3, our study further reveals the importance of exploiting IGFBP2 as a target for glioma therapy. Citation Format: YingXuan Chua, Yuexin Liu, Limei Hu, Kirsi Granberg, Maartje Verploegen, Wei Zhang. IGFBP2 promotes EGFR/STAT3 nuclear crosstalk in glioma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3338. doi:10.1158/1538-7445.AM2014-3338

A dual-targeting liposome conjugated with transferrin and arginine-glycine-aspartic acid peptide for glioma-targeting therapy

The treatment of a brain glioma remains one of the most difficult challenges in oncology. In the present study a delivery system was developed for targeted drug delivery across the blood-brain barrier (BBB) to the brain cancer cells. A cyclic arginine-glycine-aspartic acid (RGD) peptide and transferrin (TF) were utilized as targeting ligands. Cyclic RGD peptides are specific targeting ligands of cancer cells and TFs are ligands that specifically target the BBB and cancer cells. Liposome (LP) was used to conjugate the cyclic RGD and TFs to establish the brain glioma cascade delivery system (RGD/TF-LP). The LPs were prepared by the thin film hydration method and physicochemical characterization was conducted. In vitro cell uptake and three-dimensional tumor spheroid penetration studies demonstrated that the system could target endothelial and tumor cells, as well as penetrate the tumor cells to reach the core of the tumor spheroids. The results of the in vivo imaging further demonstrated that the RGD/TF-LP provided the highest brain distribution. As a result, the paclitaxel-loaded RGD/TF-LP presents the best antiproliferative activity against C6 cells and tumor spheroids. In conclusion, the RGD/TF-LP may precisely target brain glioma, which may be valuable for glioma imaging and therapy.

Isocitrate dehydrogenase 1 and 2 mutations in gliomas.

Over the past few years, new biomarkers have allowed a deeper insight into gliomagenesis and facilitated the identification of possible targets for glioma therapy. Isocitrate dehydrogenase (IDH) 1 and IDH2 mutations have been shown to be promising biomarkers for monitoring disease prognosis and predicting the response to treatment. This review summarizes recent findings in this field. Web of Science, Science Direct, and PubMed online databases were used to search for publications investigating the role of IDH in glioma. References were identified by searching for the keywords "IDH1 or IDH2 and glioma and diagnostic or predictive or prognostic" in papers published from January, 2008, to April, 2014. Only papers in English were reviewed. Publications available only as an abstract were not included. IDH1/2 mutations are tightly associated with grade II and III gliomas and secondary glioblastomas, with better prognosis and production of a recently described oncometabolite, 2-hydroxyglutarate (2HG). Although the contradictory positive effect of IDH mutation on prognosis and negative role of 2HG in tumor transformation remain unresolved, the future direction of personalized treatment strategies targeted to glioma development is likely to focus on IDH1/2 mutations.

Knockdown of PKCε expression inhibits growth, induces apoptosis and decreases invasiveness of human glioma cells partially through Stat3.

Glioma is the most common primary central nervous system tumor. Despite considerable research effort, little progress has been made in the therapeutic treatment of this disease. Protein kinase Cε (PKCε), an important intracellular signaling molecule, modulates diverse cellular functions, including cell proliferation, apoptosis, invasion and differentiation. The aim of the study is to investigate whether knockdown of PKCε expression by RNA interference (RNAi) could affect the growth, apoptosis and invasion of human glioma cells, and the involvement of the signal transducer and activator of transcription 3 (Stat3) signaling pathway in these effects. Our data showed that knockdown of PKCε expression inhibited proliferation, induced apoptosis and decreased invasiveness of human glioma cell lines U251 and U87, as well as suppressed the growth of U87 cell-derived tumors in nude mice. Moreover, PKCε physically interacts with Stat3, and knockdown of PKCε expression attenuated Stat3Ser727 phosphorylation and B-cell lymphoma-extra large (Bcl-xL) expression in the two human glioma cell lines. These results support an important role for PKCε in glioma cell growth, apoptosis and invasion, and PKCε exerting its above effects at least in part through Stat3. Thus, PKCε has the potential to be an attractive therapeutic target for glioma therapy.

Significance of interleukin-13 receptor alpha 2-targeted glioblastoma therapy.

Glioblastoma multiforme (GBM) remains one of the most lethal primary brain tumors despite surgical and therapeutic advancements. Targeted therapies of neoplastic diseases, including GBM, have received a great deal of interest in recent years. A highly studied target of GBM is interleukin-13 receptor α chain variant 2 (IL13Rα2). Targeted therapies against IL13Rα2 in GBM include fusion chimera proteins of IL-13 and bacterial toxins, nanoparticles, and oncolytic viruses. In addition, immunotherapies have been developed using monoclonal antibodies and cell-based strategies such as IL13Rα2-pulsed dendritic cells and IL13Rα2-targeted chimeric antigen receptor-modified T cells. Advanced therapeutic development has led to the completion of phase I clinical trials for chimeric antigen receptor-modified T cells and phase III clinical trials for IL-13-conjugated bacterial toxin, with promising outcomes. Selective expression of IL13Rα2 on tumor cells, while absent in the surrounding normal brain tissue, has motivated continued study of IL13Rα2 as an important candidate for targeted glioma therapy. Here, we review the preclinical and clinical studies targeting IL13Rα2 in GBM and discuss new advances and promising applications.

TGF-β promotes glioma cell growth via activating Nodal expression through Smad and ERK1/2 pathways

While there were certain studies focusing on the mechanism of TGF-β promoting the growth of glioma cells, the present work revealed another novel mechanism that TGF-β may promote glioma cell growth via enhancing Nodal expression. Our results showed that Nodal expression was significantly upregulated in glioma cells when TGF-β was added, whereas the TGF-β-induced Nodal expression was evidently inhibited by transfection Smad2 or Smad3 siRNAs, and the suppression was especially significant when the Smad3 was downregulated. Another, the attenuation of TGF-β-induced Nodal expression was observed with blockade of the ERK1/2 pathway also. Further detection of the proliferation, apoptosis, and invasion of glioma cells indicated that Nodal overexpression promoted the proliferation and invasion of tumor cells and inhibited their apoptosis, resembling the effect of TGF-β addition. Downregulation of Nodal expression via transfection Nodal-specific siRNA in the presence of TGF-β weakened the promoting effect of the latter on glioma cells growth, and transfecting Nodal siRNA alone in the absence of exogenous TGF-β more profoundly inhibited the growth of glioma cells. These results demonstrated that while both TGF-β and Nodal promoted glioma cells growth, the former might exert such effect by enhancing Nodal expression, which may form a new target for glioma therapy.

Vasculogenic mimicry: a novel target for glioma therapy

Anti-angiogenic therapy has shown promising but insufficient efficacy on gliomas. Recent studies suggest that vasculogenic mimicry (VM), or the formation of non-endothelial, tumor-cell-lined microvascular channels, occurs in aggressive tumors, including gliomas. There is also evidence of a physiological connection between the endothelial-lined vasculature and VM channels. Tumor cells, by virtue of their high plasticity, can form vessel-like structures themselves, which may function as blood supply networks. Our previous study on gliomas showed that microvessel density was comparably less in VM-positive tumors than in VM-negative tumors. Thus, VM may act as a complement to ensure tumor blood supply, especially in regions with less microvessel density. Patients with VM-positive gliomas survived a shorter period of time than did patients with VM-negative gliomas. Although the detailed molecular mechanisms for VM are not fully understood, glioma stem cells might play a key role, since they are involved in tumor tissue remodeling and contribute to neovascularization via transdifferentiation. In the future, successful treatment of gliomas should involve targeting both VM and angiogenesis. In this review, we summarize the progress and challenges of VM in gliomas.

MicroRNA-222 promotes tumorigenesis via targeting DKK2 and activating the Wnt/β-catenin signaling pathway

MiR-222 in glioma can regulate cell cycle progression and apoptosis. However, the relationship between miR-222 and Wnt/β-catenin signaling pathway in glioma remains unknown. Here, we found that the Dickkopf-2 gene (DKK2) was a direct target of miR-222 by target prediction analysis and dual luciferase reporter assay. RNA interference silencing of DKK2 proved that miR-222 overexpression led to constitutive activation of β-catenin through inhibition of DKK2 expression in glioma cells. Furthermore, miR-222 siRNA significantly inhibited tumorigenesis in vivo. Finally, Western blot analysis showed that miR-222 could regulate the expression of β-catenin and the downstream genes of Wnt/β-catenin signaling pathway. Taken together, our findings reveal a new regulatory mechanism of miR-222 and suggest that miR-222 might be a potential target in glioma therapy.

Inhibitory Effect of Neuropilin-1 Monoclonal Antibody (NRP-1 MAb) on Glioma Tumor in Mice

This article reports the effect of Neuropilin-1 monoclonal antibody (NRP-1 MAb) on glioma cell lines in vitro and the effect on nude mice bearing glioma tumor (U87) in vivo. MTT, the scratch test and transwell test were used to evaluate the inhibitory effect of NRP-1 MAb on glioma cell lines. The tissue distribution and tumor targeting capability of NRP-1 MAb in U87 Xenografts nude mice was determined in Optical Imaging. Anti-glioma experiment was carried out by NRP-1 MAb on U87 Xenografts nude mice. NRP-1 MAb was showed to inhibit the proliferation, migration and invasion of glioma cells. NRP-1 MAb can specifically target the tumor in U87 Xenografts nude mice and reduce the proliferation activity of the tumor. The results of this study indicate that NRP-1 MAb can inhibit the proliferation, migration and metastasis of glioma cell lines and can target the glioma tumor to reduce tumor growth. Therefore, NRP-1 MAb may be an effective agent for glioma-targeted therapy.