Malignant Astrocytic Tumors Research Articles

VEGFA contributes to tumor property of glioblastoma cells by promoting differentiation of myeloid-derived suppressor cells

BackgroundGlioblastoma (GBM) is a malignant astrocytic tumor and its progression involves the regulation of vascular endothelial growth factor-A (VEGFA). However, the mechanism of VEGFA in regulating GBM progression remains unclear.MethodsVEGFA mRNA expression was analyzed by quantitative real-time polymerase chain reaction. Protein expression of VEGFA, cluster of differentiation 9 (CD9), CD81, and transforming growth factor-β1 (TGF-β1) was detected by western blotting assay. Flow cytometry assay was conducted to assess cell proliferation, cell apoptosis and myeloid-derived suppressor cell (MDSC) differentiation. TUNEL cell apoptosis detection kit was utilized to analyze cell apoptosis of tumors. Angiogenic capacity was investigated by tube formation assay. Transwell assay was used to assess cell migration and invasion. The effect of VEGFA on tumor formation was determined by a xenograft mouse model assay. Immunohistochemistry assay was used to analyze positive expression rate of VEGFA in tumor tissues. TGF-β1 level was detected by enzyme-linked immunosorbent assay.ResultsVEGFA expression was upregulated in GBM tissues, GBM cells, and exosomes from GBM patients and GBM cells. VEGFA silencing led to decreased cell proliferation, tube formation, migration and invasion and increased cell apoptosis. Moreover, VEGFA knockdown also delayed tumor formation. VEGFA promoted MDSC differentiation and TGF-β1 secretion by MDSCs by being packaged into exosomes. In addition, TGF-β1 knockdown displayed similar effects with VEGFA silencing on GBM cell phenotypes, and MDSCs attenuated VEGFA knockdown-induced effects by secreting TGF-β1 in A172 and U251 cells.ConclusionVEGFA contributed to tumor property of GBM cells by promoting MDSC differentiation and TGF-β1 secretion by MDSCs, providing potential targets for GBM treatment.

Treatments for Spinal Cord Malignant Astrocytic Tumors : Up to Date

Treatments for Spinal Cord Malignant Astrocytic Tumors : Up to Date

Acute viral ensefalitis and glioblastoma multiforme; 2 case reports

Viral encephalitis is an acute febrile disease, manifested by changes in consciousness, focal neurological findings, and seizures, causing damage to the parenchymal tissue of the central nervous system. Glioblastoma multiforme (GBM) is the most malignant astrocytic tumor that is mostly supratentorial, multifocal/multicentric, with low differentiation, vascular proliferation, necrosis, and intense infiltration into surrounding tissues. A 55-year-old male patient was evaluated in the emergency department due to a sudden onset of consciousness change and behavior disorder. Leukocytosis and T2-FLAIR hyperintense lesion in the left temporal lobe were detected (Fig. 1). LP couldn’t be performed because it was not allowed. The patient improved with treatment. The control brain imaging revelead growing lesion and contrast enhancement. He had undergone operation and diagnosed as GBM. A 63-year-old male patient was observed with seizures when he evaluated in the emergency department because of blurring of consciousness. Diffusion restriction was observed in the medial of left temporal lobe. He hospitalized with the diagnosis of encephalitis and started treatment. The patient's cerebrospinal fluid HSVtype2 IgM was positive. After evaluating the atypical contrast enhancement on control MRI (Fig. 2) the patient was operated and diagnosed as GBM. In the first case, the patient who presented with acute onset encephalitis clinic was diagnosed with GBM in our follow-up, while in the second case the presence of concurrent GBM was noted of the patient who was diagnosed with definite encephalitis by viral markers. For evaluation of patients with encephalitis, high-grade brain tumors should be considered for bearer and additional diagnosis and followed up clinically/radiologically.

Malignant Astrocytic Tumor Progression Potentiated by JAK-mediated Recruitment of Myeloid Cells.

Purpose: While the tumor microenvironment has been known to play an integral role in tumor progression, the function of nonresident bone marrow-derived cells (BMDC) remains to be determined in neurologic tumors. Here we identified the contribution of BMDC recruitment in mediating malignant transformation from low- to high-grade gliomas.Experimental Design: We analyzed human blood and tumor samples from patients with low- and high-grade gliomas. A spontaneous platelet-derived growth factor (PDGF) murine glioma model (RCAS) was utilized to recapitulate human disease progression. Levels of CD11b+/GR1+ BMDCs were analyzed at discrete stages of tumor progression. Using bone marrow transplantation, we determined the unique influence of BMDCs in the transition from low- to high-grade glioma. The functional role of these BMDCs was then examined using a JAK 1/2 inhibitor (AZD1480).Results: CD11b+ myeloid cells were significantly increased during tumor progression in peripheral blood and tumors of glioma patients. Increases in CD11b+/GR1+ cells were observed in murine peripheral blood, bone marrow, and tumors during low-grade to high-grade transformation. Transient blockade of CD11b+ cell expansion using a JAK 1/2 Inhibitor (AZD1480) impaired mobilization of these cells and was associated with a reduction in tumor volume, maintenance of a low-grade tumor phenotype, and prolongation in survival.Conclusions: We demonstrate that impaired recruitment of CD11b+ myeloid cells with a JAK1/2 inhibitor inhibits glioma progression in vivo and prolongs survival in a murine glioma model. Clin Cancer Res; 23(12); 3109-19. ©2016 AACR.

Correlation of ADC Map with the Ki-67 Index in Glial Tumor Prognosis in Patients of Stereotaxic Ward

Background and Purpose: There has been no report in which preoperative evaluation of ADC for prediction of post therapeutic outcome was presented. The aim of our study was to retrospectively evaluation the use of the apparent diffusion coefficient (ADC) for the prediction of malignancy and the outcome of malignant astrocytic tumors.Methods: We reviewed MRI of 26 male and 14 female patients with a pathologic diagnosis of a malignant astrocytic tumor.Results: There was a relatively significant correlation between Ki-67 LI and minimum ADC was noted for the asterocitoma group (r=−0.701, P<0.001) or the oligodendroglioma group (r=−0.634, P =0.027) and more significantly in oligoastrocitoma group (r=−1.000) separately. There was a significant negative correlation between these parameters for the malignant glial and oligodenroglial tumors as a whole (r=−0.634, P =0.027).Conclusion: The ADC analysis could be considered as one of the clinically accessible techniques used for prediction of outcome of malignant astrocytic tumors, and it might be useful for planning primary treatment modality in patients with these malignant tumors.

ATRX, IDH1-R132H and Ki-67 immunohistochemistry as a classification scheme for astrocytic tumors.

Recurrence and progression to higher grade lesions are key biological events and characteristic behaviors in the evolution process of glioma. Malignant astrocytic tumors such as glioblastoma (GBM) are the most lethal intracranial tumors. However, the clinical practicability and significance of molecular parameters for the diagnostic and prognostic prediction of astrocytic tumors is still limited. In this study, we detected ATRX, IDH1-R132H and Ki-67 by immunohistochemistry and observed the association of IDH1-R132H with ATRX and Ki-67 expression. There was a strong association between ATRX loss and IDH1-R132H (p<0.0001). However, Ki-67 high expression restricted in the tumors with IDH1-R132H negative (p=0.0129). Patients with IDH1-R132H positive or ATRX loss astrocytic tumors had a longer progressive- free survival (p<0.0001, p=0.0044, respectively). High Ki-67 expression was associated with shorter PFS in patients with astrocytic tumors (p=0.002). Then we characterized three prognostic subgroups of astrocytic tumors (referred to as A1, A2 and A3). The new model demonstrated a remarkable separation of the progression interval in the three molecular subgroups and the distribution of patients’ age in the A1-A2-A3 model was also significant different. This model will aid predicting the overall survival and progressive time of astrocytic tumors’ patients.

Rhamnose-coated superparamagnetic iron-oxide nanoparticles: an evaluation of their in vitro cytotoxicity, genotoxicity and carcinogenicity.

Tumor recurrence after the incomplete removal of a tumor mass inside brain tissue is the main reason that scientists are working to identify new strategies in brain oncologic therapy. In particular, in the treatment of the most malignant astrocytic tumor glioblastoma, the use of magnetic nanoparticles seems to be one of the most promising keys in overcoming this problem, namely by means of magnetic fluid hyperthermia (MFH) treatment. However, the major unknown issue related to the use of nanoparticles is their toxicological behavior when they are in contact with biological tissues. In the present study, we investigated the interaction of glioblastoma and other tumor cell lines with superparamagnetic iron-oxide nanoparticles covalently coated with a rhamnose derivative, using proper cytotoxic assays. In the present study, we focused our attention on different strategies of toxicity evaluation comparing different cytotoxicological approaches in order to identify the biological damages induced by the nanoparticles. The data show an intensive internalization process of rhamnose-coated iron oxide nanoparticles by the cells, suggesting that rhamnose moiety is a promising biocompatible coating in favoring cells' uptake. With regards to cytotoxicity, a 35% cell death at a maximum concentration, mainly as a result of mitochondrial damages, was found. This cytotoxic behavior, along with the high uptake ability, could facilitate the use of these rhamnose-coated iron-oxide nanoparticles for future MFH therapeutic treatments.

CBIO-16NON-STEROIDAL ANTI-INFLAMMATORY DRUGS ENHANCE THE THERAPEUTIC EFFECTS OF TEMOZOLOMIDE AND RADIATION AGAINST MALIGNANT ASTROCYTIC TUMOR CELLS IN VITRO

BACKGROUND: The present study aimed to define the anti-tumor effects of aspirin (ASA) and celecoxib (CXB) alone or combined with temozolomide (TMZ) and/or irradiation (XRT), against C6, U87MG and T98G malignant astrocytic tumor cell lines in vitro. METHODS: Cell viability, cell cycles and apoptosis were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, flow cytometry and terminal deoxynucleotidyl transferase-mediated nick end-labeling assays, respectively. RESULTS: Aspirin and CXB exerted similar anti-tumor effects by inducing cell cycle arrest and apoptosis. Aspirin and CXB induced the G0/G1 and G2/M phases of cell cycle arrest respectively, in all three malignant astrocytic tumor cell lines, whereas ASA with TMZ induced G2/M cell cycle arrest in the C6 and U87MG lines. The viability of malignant astrocytic tumor cell lines was reduced more effectively by ASA or CXB when combined with TMZ and XRT than by any of these agents alone or by a combination of any two modalities in the C6 and T98G cell lines. CONCLUSIONS: Both ASA and CXB enhance the therapeutic effects of concomitant XRT and TMZ and thus might serve as a novel strategy for treating malignant astrocytic tumors.

Silibinin Inhibits Glioblastoma Cell Proliferation via Akt/S6/4EBP1 and Stat3 Signaling Pathways In Vitro

Glioblastoma is the most common primary and lethal brain tumor in humans. These malignant astrocytic tumors exhibit high proliferation rates and acquire resistance against many therapeutic regimens. Despite aggressive treatment including surgery, radiation, and chemotherapy, the median survival time of 12‐15 months after diagnosis has remained unchanged.Thus, new effective strategies for controlling glioblastoma are required. Because glioblastoma cells like any cancer cells avoid differentiation and apoptosis, the induction of differentiation and apoptosis in glioblastoma cells may be considered as a potential treatment strategy. Silibinin, a natural polyphenolic flavonoid, is a major bioactive component of silymarin, which is isolated from the plant milk thistle. Recent studies have indicated that silibinin has anticancer activities in various cancers including prostate cancer in both in vitro and in vivo models. The present study investigated the effect of silibinin on glioblastoma cell proliferation in vitro. U87MG cells were grown on well tissue culture plates and cell viability was measured by MTT assay. The expression and activity of AKT, S6K, 4EBP1, and STAT3 proteins were measured by Western blot analysis. Silibinin induced cell death as well as inhibited proliferation in a dose‐ and time‐dependent manner. Accordingly, levels of biologically active phospho‐AKT, phospho‐S6K, phospho‐4EBP1 and phospho‐STAT3 were decreased in a dose‐ and time‐dependent manner. This study demonstrates that silibinin bears an anti‐oncogenic property via inhibition of PI3K/Akt and STAT pathways against GBM cells in vitro. Thus, this study promises a great potential agent for Glioblastoma. Study supported by the science research funds of AMS College of Pharmacy, LIU, NY

The long-term risk of malignant astrocytic tumors after structural brain injury--a nationwide cohort study.

Neoplastic transformation of damaged astrocytes has been proposed as a possible pathological mechanism behind malignant astrocytic tumors. This study investigated the association between structural brain injuries causing reactive astrogliosis and long-term risk for malignant astrocytic tumors. The cohort consisted of all individuals living in Denmark between 1978 and 2011. The personal identification number assigned to all individuals allowed retrieval of diagnoses of traumatic brain injury, cerebral ischemic infarction, and intracerebral hemorrhage from the National Patient Discharge Register. Diagnoses of anaplastic astrocytoma and glioblastoma multiforme (World Health Organization grades III and IV) were retrieved from the Danish Cancer Registry. Rate ratios (RR's) were estimated using log-linear Poisson regression. In a cohort of 8.2 million individuals, 404 812 experienced a structural brain injury and 6152 developed a malignant astrocytic tumor. No significant association was observed 1-4 years after a structural brain injury (RR = 1.14; 95% CI: 0.87-1.46), whereas the long-term (5+ y) risk for malignant astrocytic tumors was significantly reduced (RR = 0.68; 95% CI: 0.49-0.90) compared with no injury. The specific long-term risks by type of injury were: traumatic brain injury RR = 0.32 (95% CI: 0.10-0.75); cerebral ischemic infarction RR = 0.69 (95% CI: 0.47-0.96); and intracerebral hemorrhage RR = 1.39 (95% CI: 0.64-2.60). We found no evidence for an association between structural brain injury and malignant astrocytic tumors within the first 5 years of follow-up. However, our study indicated a protective effect of astrogliosis-causing injuries 5 or more years after structural brain injury.

Wnt signaling transcription factors TCF-1 and LEF-1 are upregulated in malignant astrocytic brain tumors.

Since the discovery of the TCF/LEF family of transcription factors, their functions have been under intensive investigation in the area of cancer biology. The work presented in this paper focused on the changes in TCF-1 and LEF-1 expression levels in a set of astrocytic brain tumors. Protein expression was detected using immunohistochemistry and then evaluated by Ellipse software (ViDiTo, Slovakia). Statistical evaluations were performed with the SPSS statistical package, version 14.0 (SPSS Inc., Chicago, IL, USA). Strong TCF-1 and LEF-1 expression was observed in 51.6% and 71% of glioblastoma samples. Statistical analysis confirmed significant differences in protein expression levels associated to 3 important values, weak expression of TCF-1, weak expression of LEF-1 and strong expression of LEF-1. Analysis of variances performed on the total sample also indicated significant differences in the values of TCF-1 weak (F=2.804; p=0.045), LEF-1 weak (F=4.255; p=0.008) and LEF-1 strong (F=5.498; p=0.002) with regard to malignancy grade. Thus, glioblastomas were characterized by -in relative terms- the lowest values for weak expression of TCF-1 and LEF-1, combined with the highest values of LEF-1 strong expression. The F-ratios for two variables (LEF-1 strong and LEF-1 weak) indicated that differences between astrocytomas (II, III) and glioblastomas were statistically significant (p<0.02). Discriminant function analysis further showed that strong LEF-1 expression alone could discriminate between astrocytomas (II, III) and glioblastomas. Elevated TCF-1 and LEF-1 expression is characteristic of malignant gliomas. LEF-1, in particular, may serve as a potential marker for malignant transformation.

MicroRNA-137 is downregulated in glioblastoma and inhibits the stemness of glioma stem cells by targeting RTVP-1

Glioblastomas (GBM), the most common and aggressive malignant astrocytic tumors, contain a small subpopulation of cancer stem cells (GSCs) that are implicated in therapeutic resistance and tumor recurrence. Here, we study the expression and function of miR-137, a putative suppressor miRNA, in GBM and GSCs. We found that the expression of miR-137 was significantly lower in GBM and GSCs compared to normal brains and neural stem cells (NSCs) and that the miR-137 promoter was hypermethylated in the GBM specimens. The expression of miR-137 was increased in differentiated NSCs and GSCs and overexpression of miR-137 promoted the neural differentiation of both cell types. Moreover, pre-miR-137 significantly decreased the self-renewal of GSCs and the stem cell markers Oct4, Nanog, Sox2 and Shh. We identified RTVP-1 as a novel target of miR-137 in GSCs; transfection of the cells with miR-137 decreased the expression of RTVP-1 and the luciferase activity of RTVP-1 3'-UTR reporter plasmid. Furthermore, overexpression of RTVP-1 plasmid lacking its 3'-UTR abrogated the inhibitory effect of miR-137 on the self-renewal of GSCs. Silencing of RTVP-1 decreased the self-renewal of GSCs and the expression of CXCR4 and overexpression of CXCR4 abrogated the inhibitory effect of RTVP-1 silencing on GSC self-renewal. These results demonstrate that miR-137 is downregulated in GBM probably due to promoter hypermethylation. miR-137 inhibits GSC self-renewal and promotes their differentiation by targeting RTVP-1 which downregulates CXCR4. Thus, miR-137 and RTVP-1 are attractive therapeutic targets for the eradication of GSCs and for the treatment of GBM.

A role for LRIG1 in the regulation of malignant glioma aggressiveness

The molecular mechanisms that drive the development and aggressive progression of malignant astrocytic tumors remain obscure. Recently, in the search for endogenous negative regulators of EGF receptor, LRIG1 was cloned and characterized as a putative tumor suppressor gene often downregulated in various human tumors, including astrocytic tumors. Although several studies have implicated the function of LRIG1 in the inhibition of tumorigenesis, its precise role and potential underlying mechanisms remain obscure. Therefore, we generated a full-length expression vector to overexpress LRIG1 in the U251 malignant glioma cell line. Introduction of exogenous LRIG1 into glioma cells inhibited cell proliferation manifested by MTT and soft agar clone assay in vitro and subcutaneously tumor xenografts. On the other hand, LRIG1 overexpression inhibited glioma growth by significantly changing the expression pattern of cyclins, resulting in delayed cell cycle. Employing transwell invasion and wound scratch assay and gelatin zymography, LRIG1 inhibited U-251 MG cell invasion and migration by attenuating MMP2 and MMP9 production. Under ligand-stimulated conditions, p-ERK levels did not change, whereas p-AKT levels were inhibited in cells with LRIG1 upregulation, indicating that LRIG1 exerts more inhibiting effects on the PI3K/AKT pathway. Our findings suggest that LRIG1 restricted glioma aggressiveness by inhibiting cell proliferation, migration and invasion. Restoration of LRIG1 to glioma cells could offer a novel therapeutic strategy.

Cytomorphology of giant cell glioblastoma: Report of a case and brief review of literature

Giant cell glioblastoma is a histological variant of glioblastoma that accounts for less than 1% of intracranial tumors and to 5% of glioblastoma. They occur at any age and are likely to affect the younger as well the older age group unlike the conventional glioblastoma multiforme (GBM). They are often located subcortically in the temporal and parietal lobes. Cytological descriptions of giant cell glioblastoma are extremely rare. We describe squash cytomorphology of giant cell glioblastoma of left posterior frontal region in 35-year-old male. The squash smears were moderately cellular displaying malignant astrocytic tumor cells disposed in cohesive clusters and dispersed population on a necrotic background. Most striking feature was numerous multinucleated giant cells. We also discuss the differential diagnosis in light of relevant literature.

Non-Stem Cell Origin for Oligodendroglioma

Malignant astrocytic brain tumors are among the most lethal cancers. Quiescent and therapy-resistant neural stem cell (NSC)-like cells in astrocytomas are likely to contribute to poor outcome. Malignant oligodendroglial brain tumors, in contrast, are therapy sensitive. Using magnetic resonance imaging (MRI) and detailed developmental analyses, we demonstrated that murine oligodendroglioma cells show characteristics of oligodendrocyte progenitor cells (OPCs) and are therapy sensitive, and that OPC rather than NSC markers enriched for tumor formation. MRI of human oligodendroglioma also suggested a white matter (WM) origin, with markers for OPCs rather than NSCs similarly enriching for tumor formation. Our results suggest that oligodendroglioma cells show hallmarks of OPCs, and that a progenitor rather than a NSC origin underlies improved prognosis in patients with this tumor.

Abstract LB-273: Inhibition of CD95-dependent signaling for the treatment of glioblastoma multiforme

Abstract CD95 (APO-1/FAS) is a receptor that belongs to the Tumor Necrosis Factor Super Family (TNFSF). Binding of the cognate ligand (CD95L) to CD95 triggers intracellular signaling, ultimately leading to apoptotic cell death. Recent research indicates that CD95 depending on the tissue and the conditions also mediates diverse non-apoptotic functions (e.g. liver regeneration, neuronal development, inflammation and cellular migration/invasion of tumor cells). The potential impact on multiple cellular processes classifies the CD95 pathway as an attractive target for pharmacological interference. Apogenix developed APG101 a human fusion protein consisting of the extracellular domain of the CD95 receptor and the Fc-domain of an IgG antibody. APG101 can be used for the treatment of patho-physiological conditions showing an excess of CD95 induced apoptosis (e.g. acute Graft versus Host Disease, [GvHD]) and for malignancies that depend on CD95 regulated cell migration/invasion (e.g. cancer). Comprehensive, preclinical studies have demonstrated the therapeutic potential of APG101 in Glioblastoma Multiforme (GBM) and aGvHD. GBM is a malignant astrocytic tumor that is highly resistant to radiation and chemotherapy induced apoptosis. A major reason for the particular poor prognosis of GBM is the diffuse invasive growth of infiltrating tumor cell into the surrounding brain. These infiltrating tumor cells evade surgery and are a major cause for tumor relapse. For this reason treatment regimens inhibiting the invasive phenotype should be beneficial for the treatment of GBM. It was shown recently that binding of CD95L to its cognate receptor is an important trigger for the invasive growth of glioblastoma cells and that inhibition of CD95 signaling with neutralizing antibodies abolished the invasion of glioblastoma in vitro and in vivo. Data presented here indicate that APG101 is capable to interfere with the invasive phenotype of glioblastoma cell lines in vitro. Furthermore APG101 effectively reduced the migration of invading tumor cells in a syngeneic mouse model of intracranial GBM (SMA-model). In a modified experimental setup the SMA-mouse model was additionally tested for the efficacy of a combinatorial treatment of APG101 and irradiation. These experiments revealed that a combination of APG101 and sub-lethal irradiation inhibits the invasive growth of GBM cells in vivo, whereas radiation alone had no effect on invasive growth. Detailed analysis of the treatment groups indicated that the combination of APG101 and sub-lethal irradiation prevents formation of satellite tumors, an effect that could not be observed in the control groups. Based on the preclinical data set presented, APG101 is currently tested in a clinical Phase II for the treatment of GBM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-273.

Long-term Temozolomide Treatment Induces Marked Amino Metabolism Modifications and an Increase in TMZ Sensitivity in Hs683 Oligodendroglioma Cells

Gliomas account for more than 50% of all primary brain tumors. The worst prognosis is associated with gliomas of astrocytic origin, whereas gliomas with an oligodendroglial origin offer higher sensitivity to chemotherapy, especially when oligodendroglioma cells display 1p19q deletions. Temozolomide (TMZ) provides therapeutic benefits and is commonly used with radiotherapy in highly malignant astrocytic tumors, including glioblastomas. The actual benefits of TMZ during long-term treatment in oligodendroglioma patients have not yet been clearly defined. In this study, we have investigated the effects of such a long-term TMZ treatment in the unique Hs683 oligodendroglioma model. We have observed increased TMZ sensitivity of Hs683 orthotopic tumors that were previously treated in vitro with months of progressive exposure to increasing TMZ concentrations before being xenografted into the brains of immunocompromised mice. Whole-genome and proteomic analyses have revealed that this increased TMZ sensitivity of Hs683 oligodendroglioma cells previously treated for long periods with TMZ can be explained, at least partly, by a TMZ-induced p38-dependant dormancy state, which in turn resulted in changes in amino acid metabolism balance, in growth delay, and in a decrease in Hs683 oligodendroglioma cell-invasive properties. Thus, long-term TMZ treatment seems beneficial in this Hs683 oligodendroglioma model, which revealed itself unable to develop resistance against TMZ.

Isoform-Specific Contributions of Alpha-Actinin to Glioma Cell Mechanobiology

Glioblastoma Multiforme (GBM) is a malignant astrocytic tumor associated with low survival rates because of aggressive infiltration of tumor cells into the brain parenchyma. Expression of the actin binding protein a-actinin has been strongly correlated with the invasive phenotype of GBM in vivo. To probe the cellular basis of this correlation, we have suppressed expression of the nonmuscle isoforms a-actinin-1 and a-actinin-4 and examined the contribution of each isoform to the structure, mechanics, and motility of human glioma tumor cells in culture. While subcellular localization of each isoform is distinct, suppression of either isoform yields a phenotype that includes dramatically reduced motility, compensatory upregulation and redistribution of vinculin, reduced cortical elasticity, and reduced ability to adapt to changes in the elasticity of the extracellular matrix (ECM). Mechanistic studies reveal a relationship between a-actinin and non-muscle myosin II in which depletion of either a-actinin isoform reduces myosin expression and maximal cell-ECM tractional forces. Our results demonstrate that both a-actinin-1 and a-actinin-4 make critical and distinct contributions to cytoskeletal organization, rigidity-sensing, and motility of glioma cells, thereby yielding mechanistic insight into the observed correlation between a-actinin expression and GBM invasiveness in vivo.

Isoform-Specific Contributions of α-Actinin to Glioma Cell Mechanobiology

Glioblastoma Multiforme (GBM) is a malignant astrocytic tumor associated with low survival rates because of aggressive infiltration of tumor cells into the brain parenchyma. Expression of the actin binding protein α-actinin has been strongly correlated with the invasive phenotype of GBM in vivo. To probe the cellular basis of this correlation, we have suppressed expression of the nonmuscle isoforms α-actinin-1 and α-actinin-4 and examined the contribution of each isoform to the structure, mechanics, and motility of human glioma tumor cells in culture. While subcellular localization of each isoform is distinct, suppression of either isoform yields a phenotype that includes dramatically reduced motility, compensatory upregulation and redistribution of vinculin, reduced cortical elasticity, and reduced ability to adapt to changes in the elasticity of the extracellular matrix (ECM). Mechanistic studies reveal a relationship between α-actinin and non-muscle myosin II in which depletion of either α-actinin isoform reduces myosin expression and maximal cell-ECM tractional forces. Our results demonstrate that both α-actinin-1 and α-actinin-4 make critical and distinct contributions to cytoskeletal organization, rigidity-sensing, and motility of glioma cells, thereby yielding mechanistic insight into the observed correlation between α-actinin expression and GBM invasiveness in vivo.

Skin metastases of glioblastoma in the absence of intracranial progression are associated with a shift towards a mesenchymal immunophenotype: report of two cases

Glioblastoma multiforme (GBM) is the most malignantastrocytic tumour. Extra-neural spread is exceedingly rare,and usually develops at the time of intracranial progressionfollowing a surgical procedure [2–4]. Less frequently,metastases are a consequence of spontaneous tumour trans-dural extension or haematogenous spread. Here, wedescribe two unusual cases of GBM in which scalpmetastases appeared in the absence of intracranial diseaseprogression.Case 1A 48-year-old woman who presented with headache,speech disturbances and left facio-brachial paresis under-went magnetic resonance imaging (MRI), which revealed alarge right fronto-parietal mass with peripheral enhance-ment (Fig. 1a). The patient underwent gross total removalof the tumour, and a histopathological diagnosis of GBMwas made. Using immunohistochemistry, the tumour cellswere shown to co-express GFAP (intensely) and vimentin(less extensively). EGFR was positive in all tumour cellsand YKL-40 showed a faint cytoplasmic positivity in about30% of cells (Fig. 3). Conformal radiotherapy and adjuvanttemozolomide (TMZ) followed surgery. After 12 cycles,and in the absence of intracranial disease recurrence,the patient presented with a 2-cm scalp metastasis, closeto, but not contiguous with the surgical scar (Fig. 1b).A complete removal was performed and the diagnosis ofGBM was confirmed. Histologically, the metastasisshowed an infiltrating growth pattern dispersed intofibrotic tissue and consisted of a neoplastic population oflarge pleomorphic cells with a high mitotic index andstrong positivity for vimentin, while the GFAP stainingwas less diffuse than in the intracranial tumour. More-over, when compared with the primary lesion, EGFR wasnegative in the neoplastic cells, whereas a diffuse, intenseYKL-40 immunoreactivity was found (Fig. 3). The patientunderwent focal radiotherapy; 4 months later, an MRIrevealed distant intracranial progression in the righttemporal lobe. The patient received second-line chemo-therapy but soon the progressive intracranial disease ledto the patient’s death.Case 2A 53-year-old woman presented with a 1-month history ofspeech disturbances and facio-brachio-crural right motordeficit and underwent MRI, which showed a left frontalmass with contrast enhancement (Fig. 2a). She underwentcraniotomy with partial resection of the mass, and a diag-nosis of GBM was made. Immunohistochemistry showed adiffuse and intense GFAP reactivity with vimentin co-expression in a few GFAP-positive areas; EGFR positivitywas diffuse, whereas YKL-40 showed weak and focalexpression (Fig. 3). The patient underwent radiotherapyand standard TMZ treatment, and a partial response with a