Invasion as target for therapy of glioblastoma multiforme

Improved anti-glioblastoma efficacy by IL-13Rα2 mediated copolymer nanoparticles loaded with paclitaxel

Glioma presents one of the most malignant brain tumors, and the therapeutic effect is often limited due to the existence of brain tumor barrier. Based on interleukin-13 receptor α2 (IL-13Rα2) over-expression on glioma cell, it was demonstrated to be a potential receptor for glioma targeting. In this study, Pep-1-conjugated PEGylated nanoparticles loaded with paclitaxel (Pep-NP-PTX) were developed as a targeting drug delivery system for glioma treatment. The Pep-NP-PTX presented satisfactory size of 95.78 nm with narrow size distribution. Compared with NP-PTX, Pep-NP-PTX exhibited significantly enhanced cellular uptake in C6 cells (p < 0.001). The in vitro anti-proliferation evaluation showed that the IC50 were 146 ng/ml and 349 ng/ml of Pep-NP-PTX and NP-PTX, respectively. The in vivo fluorescent image results indicated that Pep-NP had higher specificity and efficiency in intracranial tumor accumulation. Following intravenous administration, Pep-NP-PTX could enhance the distribution of PTX in vivo glioma section, 1.98, 1.91 and 1.53-fold over that of NP-PTX group after 0.5, 1 and 4 h, respectively. Pep-NP-PTX could improve the anti-glioma efficacy with a median survival time of 32 days, which was significantly longer than that of PTX-NP (23 days) and Taxol(®) (22 days). In conclusion, Pep-NP-PTX is a potential targeting drug delivery system for glioma treatment.

Overexpression of SCLIP promotes growth and motility in glioblastoma cells

SCLIP, a microtubule-destabilizing phosphoprotein, is known to be involved in the development of the central nervous system (CNS). It has been well established that there are notable parallels between normal development and tumorigenesis, especially in glioma. However, no studies have examined the significance of SCLIP in gliomagenesis. To address this, we investigated the expression of SCLIP and its roles in the development of gliomas. Notably, we found that SCLIP was highly expressed in various grades of glioma samples, as compared with normal brain tissues. Overexpression of SCLIP dramatically stimulated tumor cell migration and invasion as well as proliferation and downregulation of SCLIP showed opposite effects, establishing an important oncogenic role for this gene. Furthermore, we revealed that STAT3 was required to maintain SCLIP stability, suggesting that overexpression of STAT3 may be a critical step to facilitate microtubule dynamics and subsequently promotes migration and invasion of glioma cells. Taken together, our findings demonstrate that SCLIP plays an important role in glioma pathology, and may represent a novel therapeutic strategy against human glioma.

Aggressive invasion is observed in CD133-/A2B5+ glioma-initiating cells

Glioblastoma multiforme is the most common and fatal primary brain tumor in adults. Aggressive invasion of glioblastoma cells into brain tissue often limits complete surgical resection and contributes to therapeutic resistance. The cell surface marker, CD133, has been identified as a putative stem cell marker in normal and malignant brain tissues; CD133^-/A2B5⁺ cells exhibit neural stem-like cell properties. The invasive properties and the molecular mechanisms of CD133^-/A2B5⁺ glioma-initiating cells (GICs) were investigated in the process of self-renewal and tumorigenesis. An increased number of invasive cells through matrigel and an increase in migratory cells through filters were observed in CD133^-/A2B5⁺ GIC populations compared with matched non-initiating tumor cell populations. Considerable changes were detected in expression of mRNA and protein associated with migration or invasion. CD133^-/A2B5⁺ GIC demonstrated infiltrating growth patterns and displayed greater invasive potential under fluorescent microscopy comparing with the matched non-initiating tumor cells after cells labeled with red fluorescence protein were transplanted into the brains of athymic/nude mice. CD133^-/A2B5⁺ GICs possess strong migratory and invasive capacity. These infiltrating cells in the invasive fronts may be responsible for rapid tumor recurrence following conventional treatments. CD133^-/A2B5⁺ GICs may be an important subpopulation with high invasive potential and they should not be ignored when targeting GICs to prevent GBM recurrence.

Effect of Concomitant Radiochemotherapy on Invasion Potential of Glioblastoma

Glioblastoma (GBM) is the most common primary brain tumor in adults with inevitable recurrence after oncotherapy. The insufficient effect of "gold standard" temozolomide-based concomitant radiochemotherapy may be due to the inability to prevent tumor cell invasion. Peritumoral infiltration depends mainly on the interaction between extracellular matrix (ECM) components and cell membrane receptors. Changes in invasive behaviour after oncotherapy can be evaluated at the molecular level by determining the RNA expression and protein levels of the invasion-related ECM components. The expression of nineteen ECM molecules was determined at both RNA and protein levels in thirty-one GBM samples. Fifteen GBM samples originated from the first surgical procedure on patients before oncotherapy, and sixteen GBM samples were collected at the second surgery due to local recurrence after concomitant chemoirradiation. RNA expressions were measured with qRT-PCR, and protein levels were determined by quantitative analysis of Western blots. Only MMP-9 RNA transcript level was reduced (p < 0.05) whereas at protein level, eight molecules showed changes concordant with RNA expression with significant decrease in brevican only. The results suggest that concomitant radiochemotherapy does not have sufficient impact on the expression of invasion-related ECM components of glioblastoma, oncotherapy does not significantly affect its invasive behavior. To avoid the spread of tumors into the brain parenchyma, supplementation of antiproliferative treatment with anti-invasive agents may be worth consideration in oncotherapy for glioblastoma.

Extracellular Matrix Properties Regulate the Migratory Response of Glioblastoma Stem Cells in Three-Dimensional Culture

Diffuse infiltration across brain tissue is a hallmark of glioblastoma and the main cause of unsuccessful total resection that leads to tumor reappearance. A subpopulation termed glioblastoma stem cells (GSCs) has been directly related to aggressive invasion; nonetheless, their migratory characteristics and regulation by the microenvironment are still unknown. In this study, we developed a composite matrix of hyaluronan (HA) structurally supported by a collagen-oligomer fibril network to simulate the brain tumor extracellular matrix (ECM) composition. Matrigel-coated microfibers were embedded within the matrix to create a tunable dual niche microenvironment that resembles the vascular network of the brain. This model was compared with the most commonly used in vitro three-dimensional (3D) culture formats, Matrigel and collagen type-I monomer matrices, to study how the mechanical and compositional properties of the ECM alter the migration characteristics of GSC neurospheres. The migration mode, distance, velocity, and morphology of the GSCs were monitored over a 72-h period. The cells altered their migration mode depending on the matrix composition, showing migration by expansive growth in Matrigel matrices, multicellular extension along rigid interfaces (as Matrigel glass and coated microfibers), and mesenchymal single-cell migration in collagen matrices. Velocity and distance of migration within each composition varied according to matrix mechanical properties. In the dual niche system, the presence of HA reduced velocity and number of migratory cells; however, cells that came in contact with the pseudovessels exhibited collective migration by an extensive strand and reached higher velocities than cells migrating individually across the 3D matrix. Our results show that GSCs adopt varied migration mechanisms to invade multiple ECM microenvironments, and the migration characteristics exhibited are highly influenced by the matrix physical properties. Moreover, GSC neurospheres exhibit concomitant single and collective migration as a function of the microenvironment topography to reach the most productive migration strategy.

The TWEAK receptor Fn14 is a potential cell surface portal for targeted delivery of glioblastoma therapeutics

Fibroblast growth factor-inducible 14 (Fn14; TNFRSF12A) is the cell surface receptor for the tumor necrosis factor (TNF) family member TNF-like weak inducer of apoptosis (TWEAK). The Fn14 gene is normally expressed at low levels in healthy tissues but expression is significantly increased after tissue injury and in many solid tumor types, including glioblastoma (GB; formerly referred to as 'GB multiforme'). GB is the most common and aggressive primary malignant brain tumor and the current standard-of-care therapeutic regimen has a relatively small impact on patient survival, primarily because glioma cells have an inherent propensity to invade into normal brain parenchyma, which invariably leads to tumor recurrence and patient death. Despite major, concerted efforts to find new treatments, a new GB therapeutic that improves survival has not been introduced since 2005. In this review article, we summarize studies indicating that (i) Fn14 gene expression is low in normal brain tissue but is upregulated in advanced brain cancers and, in particular, in GB tumors exhibiting the mesenchymal molecular subtype; (ii) Fn14 expression can be detected in glioma cells residing in both the tumor core and invasive rim regions, with the maximal levels found in the invading glioma cells located within normal brain tissue; and (iii)

TWEAK

Fn14 engagement as well as Fn14 overexpression can stimulate glioma cell migration, invasion and resistance to chemotherapeutic agents in vitro. We also discuss two new therapeutic platforms that are currently in development that leverage Fn14 overexpression in GB tumors as a way to deliver cytotoxic agents to the glioma cells remaining after surgical resection while sparing normal healthy brain cells.

The Critical Role of Rab31 in Cell Proliferation and Apoptosis in Cancer Progression

Rab31, a member of the Ras superfamily, is reported to play a role in tumor development and progression. However, the detailed role of Rab31 in proliferation and apoptosis of cancer cells is still unclear. Here, we used different cell lines, such as glioblastoma, and cervical cancer, to investigate the role of Rab31 in cancer progression. We found that Rab31 promotes U87 and SiHa cell proliferation via activation of G1/S checkpoint transitions, accompanied with an increase of cyclin D1, cyclin A, and cyclin B1. Meanwhile, Rab31 inhibits U87 and SiHa cell apoptosis, and decreased the BAX and PIG3 expression, but enhanced BCL2 expression. In addition, Rab31 induces N-cadherin, Vimentin, and Snail expression, and inhibits E-cadherin expression to regulate proliferation and migration. Besides, we observed that ERK1/2 and PI3k/AKT pathways are required for Rab31-induced cell proliferation and migration. In vivo, the knockdown of Rab31 suppresses tumor mass growth. In conclusion, our data highlight the crucial role of Rab31 in cancer progression, proliferation, and apoptosis, and indicates that Rab31 may be a useful and effective target for the clinical therapy of most cancers.

Sublethal dose of irradiation enhances invasion of malignant glioma cells through p53-MMP 2 pathway in U87MG mouse brain tumor model

Background

Glioblastoma is a highly lethal neoplasm that frequently recurs locally after radiotherapy, and most of these recurrences originate from near the irradiated target field. In the present study, we identified the effects of radiation on glioma invasion and p53, TIMP-2, and MMP-2 expression through in vitro and in vivo experiments.

Methods

The U87MG (wt p53) and U251 (mt p53) human malignant glioma cell lines were prepared, and the U2OS (wt 53) and Saos2 (del p53) osteosarcoma cell lines were used as p53 positive and negative controls. The four cell lines and p53 knock-downed U87MG cells received radiation (2–6 Gy) and were analyzed for expression of p53 and TIMP-2 by Western blot, and MMP-2 activity was detected by zymography. In addition, the effects of irradiation on directional invasion of malignant glioma were evaluated by implanting nude mice with bioluminescent u87-Fluc in vivo followed by MMP-2, p53, and TIMP-2 immunohisto-chemistry and in situ zymography.

Results

MMP-2 activity and p53 expression increased in proportional to the radiation dose in cell lines with wt p53, but not in the cell lines with del or mt p53. TIMP-2 expression did not increase in U87MG cells. MMP-2 activity decreased in p53 knock-downed U87MG cells but increased in the control group. Furthermore, radiation enhanced MMP-2 activity and increased tumor margin invasiveness in vivo. Tumor cells invaded by radiation overexpressed MMP-2 and p53 and revealed high gelatinolytic activity compared with those of non-radiated tumor cells.

Conclusion

Radiation-induced upregulation of p53 modulated MMP-2 activity, and the imbalance between MMP-2 and TIMP-2 may have an important role in glioblastoma invasion by degrading the extracellular matrix. Bioluminescent “U87-Fluc”was useful for observing tumor formation without sacrifice after implanting tumor cells in the mouse brain. These findings suggest that the radiotherapy involved field for malignant glioma needs to be reconsidered, and that future trials should investigate concurrent pharmacologic therapies that inhibit invasion associated with radiotherapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-015-0475-8) contains supplementary material, which is available to authorized users.

CXCL12/CXCR4 Axis Upregulates Twist to Induce EMT in Human Glioblastoma

In recent decades, the chemokine receptor CXCR4 and its ligand CXCL12 have been extensively reported to be associated with tumorigenesis. In addition, Twist signaling induces the epithelial-mesenchymal transition (EMT) process in glioblastoma development. In the present study, in vitro assays were used to investigate the role of CXCR4 and Twist in human glioblastoma. We explored the impact of CXCR4 and Twist on human glioblastoma using in vitro protein and gene assays. We found the administration of CXCL12 upregulated the expression of p-ERK, p-AKT, Twist, N-cadherin, and MMP9 in U87 cells, whereas the increase of E-cadherin protein was affected. Subsequently, Twist activity and EMT signaling were directly influenced by PD98059 and LY294002. Most importantly, the genetic silencing of Twist inhibited CXCL12-induced EMT occurrence, including proliferation, migration, and tumor formation of U87 cells. In conclusion, CXCL12/CXCR4 pathway activates ERK and PI3K/AKT signaling to upregulate Twist pathway, leading to the progression of EMT in human glioblastoma. Our study creates a new stage for molecule-targeted therapy of human glioblastoma.

High-content analysis of tumour cell invasion in three-dimensional spheroid assays

Targeting infiltrating tumour cells is an attractive way of combating cancer invasion and metastasis. Here we describe a novel and reproducible method for high content analysis of invading cells using multicellular tumour spheroid assays in a high grade glioma model. Live cell imaging of spheroids generated from glioma cell lines, U87 and U251, gave insight into migration dynamics and cell morphology in response to anti-migratory drugs. Immunofluorescence imaging confirmed cytoskeletal rearrangements in the treated cells indicating a direct effect on cell morphology. Effect on migration was determined by a Migration Index (MI) from brightfield images which confirmed anti-migratory activity of the drugs. A marked effect on the core with treatment suggestive of disordered proliferation was also observed. A newly developed technique to prepare the spheroids and migratory cells for immunohistochemistry allowed an assessment of response to drug treatment with a selection of markers. A difference in protein expression was noted between cells maintained within the core and migratory cells indicative of the presence of cell subpopulations within the spheroid core. We conclude that this high content analysis allows researchers to perform screening of anti-tumour invasion compounds and study their effects on cellular dynamics, particularly in relation to protein expression, for the first time.

Reconciling the discrepancies on the involvement of large-conductance Ca(2+)-activated K channels in glioblastoma cell migration

Glioblastoma (GBM) is the most common and aggressive primary brain tumor, and is notable for spreading so effectively through the brain parenchyma to make complete surgical resection virtually impossible, and prospect of life dismal. Several ion channels have been involved in GBM migration and invasion, due to their critical role in supporting volume changes and Ca(2+) influx occuring during the process. The large-conductance, Ca(2+)-activated K (BK) channels, markedly overexpressed in biopsies of patients with GBMs and in GBM cell lines, have attracted much interest and have been suggested to play a central role in cell migration and invasion as candidate channels for providing the ion efflux and consequent water extrusion that allow cell shrinkage during migration. Available experimental data on the role of BK channel in migration and invasion are not consistent though. While BK channels block typically resulted in inhibition of cell migration or in no effect, their activation would either enhance or inhibit the process. This short review reexamines the relevant available data on the topic, and presents a unifying paradigm capable of reconciling present discrepancies. According to this paradigm, BK channels would not contribute to migration under conditions where the [Ca(2+)] i is too low for their activation. They will instead positively contribute to migration for intermediate [Ca(2+)] i , insufficient as such to activate BK channels, but capable of predisposing them to cyclic activation following oscillatory [Ca(2+)] i increases. Finally, steadily active BK channels because of prolonged high [Ca(2+)] i would inhibit migration as their steady activity would be unsuitable to match the cyclic cell volume changes needed for proper cell migration.

Identification of Commonly Dysregulated Genes in Non-small-cell Lung Cancer by Integrated Analysis of Microarray Data and qRT-PCR Validation

BACKGROUND

Non-small-cell lung cancer (NSCLC), the most common lung cancer, leads to the largest number of cancer-related deaths worldwide. There are many studies to identify the differentially expressed genes (DEGs) between NSCLC and normal control (NC) tissues by means of microarray technology. Because of the inconsistency of the microarray data sets, we performed an integrated analysis to identify DEGs and analyzed their biological function.

METHODS AND RESULTS

We combined 15 microarray data sets and identified 1063 DEGs between NSCLC and NC tissues; in addition, we found that the DEGs were enriched in regulation of cell proliferation process and focal adhesion signaling pathway. The protein-protein interaction network analysis for the top 20 significantly DEGs revealed that CAV1, COL1A1, and ADRB2 were the significant hub proteins. Finally, we employed qRT-PCR to validate the meta-analysis approach by determining the expression of the top 10 most significantly DEGs and found that the expression of these genes were significantly different between tumor and NC tissues, in accordance with the results of meta-analysis.

CONCLUSION

qRT-PCR results indicated that the meta-analysis approach in our study was acceptable. Our data suggested that some of the DEGs, including MMP12, COL11A1, THBS2, FAP, and CAV1, may participate in the pathology of NSCLC and could be applied as potential markers or therapeutic targets for NSCLC.

The Downregulation of MicroRNA-146a Modulates TGF-β Signaling Pathways Activity in Glioblastoma

Transforming growth factor-β (TGF-β) is considered to be one of the main factors responsible for glioblastoma tumorigenesis. MicroRNAs have recently been shown to regulate cell proliferation, differentiation, and apoptosis. However, the involvement of miRNA-146a in TGF-β1-induced glioblastoma development remains largely unknown. Here, miRNA-164a transfection was used to overexpress miRNA-164a in U87, and then real-time quantitative PCR and Western blot were applied to detect the gene transcription and protein expression. In addition, MTT and wound healing assay were also used to observe cell proliferation and migration. Our data revealed that miRNA-146a was downregulated by TGF-β1 treatment, but upregulated by miRNA-164a transfection. MiRNA-146a overexpression significantly reduced SMAD4 protein expression instead of p-SMAD2. Besides, miRNA-146a overexpression also decreased the messenger RNA (mRNA) and protein expression of epidermal growth factor receptor (EGFR) and MMP9 as well as the p-ERK1/2 level. Furthermore, the upregulation of miRNA-146a suppressed TGF-β1-mediated U87 proliferation and migration. These results demonstrate that miRNA-146a acts as a novel regulator to modulate the activity and transduction of TGF-β signaling pathways in glioblastoma, and the downregulation of miRNA-146a is required for overexpression of EGFR and MMP9, which can be considered an efficiently therapeutic target and a better understanding of glioblastoma pathogenesis.

The Clinical Implications of Transforming Growth Factor Beta in Pathological Grade and Prognosis of Glioma Patients: A Meta-Analysis

The transforming growth factor beta (TGF-β) pathway plays a key role in oncogenesis of advanced cancers. However, the effects of TGF-β pathway on gliomas are still controversial. So, it is essential to conduct a meta-analysis to determine their correlations. Eligible studies were included, and then odds ratios (ORs), standard mean differences (SMDs), and hazard ratios (HRs) with 95 % confidence intervals (95% CIs) were estimated. Funnel plots were available for evaluation of publication bias. In this meta-analysis, all 14 eligible studies involving 875 patients were included and conducted in China. Six studies with dichotomous data revealed altered TGF-β expression in glioma tissues was closely associated with high WHO grade (III + IV) (OR 4.39, 95% CI 2.90-6.63; p = 0.000), meanwhile, seven studies with continuous data also demonstrated TGF-β expression intensity extremely related to high grade (SMD -2.44, 95% CI -2.71, -2.16; p = 0.000). To our interest, TGF-β expression was associated with old age (OR 0.59, 95% CI 0.36-0.93; p = 0.025) rather than gender (OR 1.04, 95% CI 0.64-1.67; p = 0.884). Besides, TGF-β expression significantly correlated to 3-year-OS (n = 2; HR 2.53, 95% CI 1.18-5.41; p = 0.017) rather than 5-year-OS (n = 1; HR 1.04, 95% CI 0.66-1.64; p = 0.872) in glioma patients. No heterogeneity and publication bias were observed across all studies. Taken together, the present meta-analysis testifies TGF-β is potently associated with high grade and poor 3 years prognosis, and TGF-β test combined with survivin [1 Mol Neurobiol] and MMP9 [2 Mol Neurobiol] in glioma tissues should be clinically recommended as criteria of glioma grade in department of pathology.

STAT3 Activation in Glioblastoma: Biochemical and Therapeutic Implications

Signal transducer and activator of transcription 3 (STAT3) is a potent regulator of gliomagenesis through its induction of angiogenesis, host immunosuppression, and tumor invasion. Gain of function mutations result in constitutive activation of STAT3 in glioma cells, making STAT3 an attractive target for inhibition in cancer therapy. Nevertheless, some studies show that STAT3 also participates in terminal differentiation and apoptosis of various cell lines and in glioma with phosphatase and tensin homolog (PTEN)-deficient genetic backgrounds. In light of these findings, the utility of STAT3 as a prognostic indicator and as a target of drug therapies will be contingent on a more nuanced understanding of its pro- and anti-tumorigenic effects.

On the notion of doll's eyes

CD90 is a membrane GPI-anchored protein with one Ig V-type superfamily domain that was initially described in mouse T cells. Besides the specific expression pattern and functions of CD90 that were described in normal tissues, i.e., neurons, fibroblasts and T cells, increasing evidences are currently highlighting the possible involvement of CD90 in cancer. This review first provides a brief overview on CD90 gene, mRNA and protein features and then describes the established links between CD90 and cancer. Finally, we report newly uncovered functional connections between CD90 and endoplasmic reticulum (ER) stress signaling and discuss their potential impact on cancer development.