Primary Human Glioma Research Articles

Retraction Note to: Aplysin enhances temozolomide sensitivity in glioma cells by increasing miR‑181 level.

This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1007/s00280-020-04166-1 .

Abstract 5096: The differences in immune composition observed between astrocytomas and oligodendrogliomas are due to genetics

Abstract We and others have shown that IDH-mutant astrocytomas and oligodendrogliomas share a common lineage hierarchy and a common cell of origin. However, IDH-mutant astrocytomas are infiltrated with immunosuppressive myeloid cells from the periphery to a degree not observed in IDH-mutant oligodendrogliomas. The abundance of blood-derived myeloid cells is prognostic in IDH-mutant glioma, and myeloid-derived suppressive cells are a barrier to emerging immunotherapies. Nonetheless, the cause of the differences observed between IDH-mutant subtypes is unknown. We performed single-cell RNA sequencing (scRNA-seq) and/or single-cell assay for transposon-accessible chromatin sequencing (scATAC-seq) on a cohort of 30 human primary IDH-mutant gliomas, including both astrocytomas and oligodendrogliomas. We integrated these single-cell multi-omics data to elucidate receptor-ligand interactions between tumor cells and myeloid cells, as well as the cis-regulatory grammars and associated transcription factors regulating these interactions. We validated these interactions in situ using imaging mass-cytometry on human specimens. We identified macrophage colony-stimulating factor (CSF1) and other genes responsible for myeloid cell chemotaxis, interlukin 10 (IL10), transforming growth factor beta (TGFB1) and genes responsible for promoting aberrant myeloid activation, as differentially expressed and showing differential chromatin accessibility between astrocytomas and oligodendrogliomas. The promoters of these genes were enriched for STAT3, SOX2, and SOX17/OCT4 recognition motifs, which were also differentially enriched between astrocytomas and oligodendrogliomas in our scATAC-seq data and differentially expressed in our scRNA-seq data. Since the scATAC-seq peaks in these genes correlated with known binding sites of the chromatin-modifying enzyme ATRX, and since ATRX possesses loss-of-function mutations in over %80 of IDH-mutant astrocytomas but almost never in oligodendrogliomas, we hypothesize that the observed differences in myeloid abundance are driven by a loss of ATRX binding in key chemotactic and immunosuppressive cytokines and their upstream transcription factors. To test this hypothesis, we knocked out ATRX in a a syngeneic, immunocompetent glioma mouse model using CRISPR and profiled the resulting tumors via a battery of genomics and protein-level assays. We conclude that the differences in immune composition between IDH-mutant glioma subtypes are due to genetics. In particular, ATRX loss of function in IDH-mutant astrocytoma leads to chromatin changes in STAT3 and downstream effector cytokines, resulting in a greater influx of immunosuppressive myeloid cells. Citation Format: Lin Wang, Husam Babikir, Karin Shamardani, Francisca Catalan, Aaron Diaz. The differences in immune composition observed between astrocytomas and oligodendrogliomas are due to genetics [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5096.

Abstract 1266: Mutant IDH1 alters epigenetic regulation to promote stemness in low grade glioma: Deciphering signaling pathways altered by mIDH1 inhibition

Abstract Greater than 75% of Low Grade Gliomas (LGG) harbor a mutation in isocitrate dehydrogenase 1 (IDH1) and this molecular subgroup also exhibits mutations in TP53 and ATRX. Mutant IDH1 often recurs and presents with a more aggressive phenotype that is refractory to existing therapies. The production of an oncometabolite, 2-hydroxyglutarate by mutant IDH1 (mIDH1) has been shown to induce histone and DNA hypermethylation. Pharmacological inhibition of mIDH1 (AGI-5198) can restore expression of genes involved in neural differentiation. We hypothesize that mIDH1 remodels chromatin to promote a stem cell-like transcriptional state. Recent single cell RNA-seq data from primary mIDH1 astrocytoma and oligodendroglioma has identified an undifferentiated pool of tumor cells with a neural stem/progenitor transcriptional profile. We aim to identify unique regulatory networks in SF10602, a human primary glioma culture derived from a surgical biopsy, which endogenously expresses mIDH1.We treated SF10602 with AGI-5198 every 2 days for 1 week. We observed a global reduction in histone marks: H3K4me3, H3K36me3, and H3K27me3. This reversibility of histone hypermethylation has previously been described in mIDH1 tumor lines treated with mIDH1 inhibitors that block 2HG production. We confirmed that mIDH1 inhibition reduced 2HG levels by collecting condition media and performing liquid chromatography mass spectrometry. We performed a temporal micrococcal nuclease (Mnase) digestion to assess chromatin accessibility and we observed enhanced chromatin condensation following mIDH1 inhibition. To evaluate if the reversion of chromatin organization resulting from mIDH1 inhibition impacts neural differentiation pathways we performed RNA-seq. We identified 496 differentially up-regulated and 893 down-regulated genes (log2>+/-0.6) comparing SF10602 with/out AGI-5198. Following gene set enrichment analysis, we observed upregulation of pathways involved in epigenetic regulation, DNA conformation and neuronal development. Additionally, we observed downregulation of pathways involved in cell polarity and transcription factor activity. In future work, we will perform ChIP-seq to define enhancers and promoters that regulate stem cell-like characteristics. These findings will reveal novel genomic loci unique to mIDH1 glioma. SC is supported by the T32 Cancer Biology Training Grant, the work is supported by grants from NIH/NINDS to MGC and PRL. Citation Format: Stephen Carney, Brandon Zhu, Padma Kadiyala, Maria Garcia-Fabiani, Preethi Gorla, Felipe Nunez, Pedro R. Lowenstein, Maria G. Castro. Mutant IDH1 alters epigenetic regulation to promote stemness in low grade glioma: Deciphering signaling pathways altered by mIDH1 inhibition [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1266.

ET-04 MOLECULAR TARGETED THERAPY AGAINST (PRO)RENIN RECEPTOR FOR GLIOBLASTOMA

INTRODUCTION(Pro)renin receptor(PRR) is part of the Wnt receptor complex. Wnt/β-catenin signaling pathway (Wnt signaling) plays important role in pathogenesis and self-renewal of glioblastoma (GBM), or differentiation of glioma stem cell. We previously reported that PRR activate Wnt signaling, PRR expression correlated with malignancy of glioma, and treatment with PRR siRNA reduced the proliferative capacity. This time, we have developed monoclonal antibodies against PRR and examined their effects in GBM.MATERIAL AND METHODSWe used GBM cell line (U251MG and U87MG) and primary human glioma stem cell line (MGG23). Glioma stem-like cells were cultured and isolated by neurosphere method from U251MG and U87MG. PRR antibody was made targeting the extracellular domain of the PRR with rat lymph node method. WST-1 assay or MTT assay were performed to determine the cell proliferation. Apoptosis was examined by FITC labeled annexin V and propidium iodide with flow cytometry. We analyzed molecules of Wnt signaling and stem cell markers with qRT-PCR.RESULTSWe observed that PRR antibody significantly reduced cell proliferation, decreased sphere formation. Antibody suppressed cell adherent in stem-like cell. Flow cytometry showed that antibody induced apoptosis. Antibody inhibited Wnt signaling and stem cell markers.CONCLUSIONSPRR antibody reduced cell proliferation and induced apoptosis through Wnt signaling. PRR antibody also suppressed stemness. Our results demonstrated that PRR was a potential target for future glioma therapy.

Ninjurin2 overexpression promotes glioma cell growth.

Ninjurin2 (Ninj2) is an adhesion protein expressed in neurons and glial cells. The current study tested its expression and potential functions in human glioma. We show that Ninj2 mRNA and protein levels are significantly upregulated in human glioma cells and tissues. In established and primary human glioma cells, Ninj2 shRNA or knockout (by CRISPR/Cas9 gene editing) potently inhibited cell survival, growth, proliferation, cell migration and invasion, while inducing apoptosis activation. Contrarily, ectopic overexpression of Ninj2 promoted glioma cell progression in vitro. In human glioma tissues and cells, Ninj2 co-immunoprecipitated with multiple receptor tyrosine kinases (EGFR, PDGFRβ and FGFR), required for downstream Akt and Erk activation. Akt and Erk activation was potently inhibited by Ninj2 shRNA or knockout, but enhanced with ectopic Ninj2 overexpression in glioma cells. In summary, we show that Ninj2 overexpression promotes glioma cell growth.

Persistent HCMV infection of a glioblastoma cell line contributes to the development of resistance to temozolomide

Glioblastoma multiforme (GBM) is the most aggressive form of primary human gliomas. While chemotherapy using the DNA alkylating agent temozolomide (TMZ) is a first line treatment for GBMs, the development of resistance to TMZ is a common limitation to successful treatment. Human Cytomegalovirus (HCMV) is a ubiquitous β-herpesvirus that establishes a lifelong infection latent infection in host haematopoetic cells, where lytic replication of the virus is silenced. HCMV can also establish a persistent infection in hosts, where low levels of virus are lytically produced. Furthermore, multiple studies have identified HCMV DNA and/or proteins in human GBM samples, and have shown that acute infection with HCMV confers a glioblastoma stem cell (GSC) phenotype, further supporting an oncomodulatory role for HCMV in GBM progression and severity. In this current study, we examined the long-term effects of HCMV persistence to cell viability, cell proliferation, and the development of TMZ resistance over time using a glioblastoma cell line known as LN-229. Persistent HCMV infections were established and maintained in this cell line for 30 weeks without the addition of new virus. Here, we report that HCMV persistence in this cell line resulted in increased cell viability, increased cell proliferation, and a marked resistance to the DNA alkylating agent, TMZ, over time, suggesting that low levels of lytically replicating HCMV could contribute to tumor progression in GBM.

IMMU-35. COMPLEMENT SYSTEM AND GLIOBLASTOMA: AN INTRICATE RELATIONSHIP

Abstract The complement system is a vital part of the innate immune system which plays a critical role in immune surveillance and inflammatory processes. Malignant and host cells express various complement inhibitory proteins on their surface to protect against complement mediated cytotoxicity. Imbalanced complement activation triggers inflammation and alters the tumor microenvironment. Complement activation has been shown to induce proliferation and migration of breast, ovarian and lung cancer cells. At this time, the expression and functional role of the complement cascade in glioblastoma (GBM) remain elusive. Here, we investigated the role of complement proteins and their receptor expression in human primary glioma stem-like cells (GSCs) and human GBM tissues. Western blot data demonstrated a high level of expression of central complement components and their receptors in GSCs. RT-PCR data further confirmed the high expression of complement genes which was similar or higher to normal human astrocytes (HA), a cell with high baseline expression levels of complement genes. Flow cytometry analysis revealed that almost 95% of GSCs expressed the anaphylatoxin complement receptors C3aR and C5aR on their cell surfaces which was consistent with our immunohistochemistry analysis of freshly resected GBM tissues. Furthermore, anaphylatoxin C5a exposure increased the proliferation of a subgroup of GSCs while reduced in another subset. Interestingly, C5a exposure was found to increase the expression of various pro-inflammatory markers in GSCs with reduced proliferation. Fluorescence-activated cell sorting (FACS) analysis of freshly isolated human GBM tissue revealed predominant expression of C5aR on cancer cells (CD11b-/CD45- cells) rather than on immune cells. RT-PCR analysis also demonstrated high expression levels of complement genes with concomitant decrease in complement inhibitory genes in human GBM tissue. Evaluation of the differential role of the complement system in GSCs along with their role in in vivo glioma models is ongoing.

Lnc-THOR silencing inhibits human glioma cell survival by activating MAGEA6-AMPK signaling

Long non-coding RNA THOR (Lnc-THOR) binds to IGF2BP1, essential for its function. We here show that Lnc-THOR is expressed in human glioma tissues and cells. Its expression is extremely low or even undetected in normal brain tissues, as well as in human neuronal cells and astrocytes. We show that Lnc-THOR directly binds to IGF2BP1 in established and primary human glioma cells. shRNA-mediated Lnc-THOR knockdown or CRISPR/Cas9-induced Lnc-THOR knockout potently inhibited cell survival and proliferation, while provoking glioma cell apoptosis. Contrarily, forced overexpression of Lnc-THOR promoted glioma cell growth and migration. Importantly, Lnc-THOR shRNA or knockout activated MAGEA6-AMPK signaling in glioma cells. AMPK inactivation, by AMPKα1 shRNA, knockout, or dominant-negative mutation (T172A), attenuated Lnc-THOR shRNA-induced A172 glioma cell apoptosis. Moreover, CRISPR/Cas9-induced IGF2BP1 knockout activated MAGEA6-AMPK signaling as well, causing A172 glioma cell apoptosis. Significantly, Lnc-THOR shRNA was ineffective in IGF2BP1 KO A172 cells. In vivo, Lnc-THOR silencing or knockout potently inhibited subcutaneous A172 xenograft tumor growth in mice. MAGEA6 downregulation and AMPK activation were detected in Lnc-THOR-silenced/-KO A172 tumor tissues. Taken together, Lnc-THOR depletion inhibits human glioma cell survival possibly by activating MAGEA6-AMPK signaling.

PMEPA1 isoform a drives progression of glioblastoma by promoting protein degradation of the Hippo pathway kinase LATS1

The Hippo signaling pathway controls organ development and is also known, in cancer, to have a tumor suppressing role. Within the Hippo pathway, we here demonstrate, in human gliomas, a functional interaction of a transmembrane protein, prostate transmembrane protein, androgen induced 1 (PMEPA1) with large tumor suppressor kinase 1 (LATS1). We show that PMEPA1 is upregulated in primary human gliomas. The PMEPA1 isoform PMEPA1a was predominantly expressed in glioma specimens and cell lines, and ectopic expression of the protein promoted glioma growth and invasion in vitro and in an orthotopic xenograft model in nude mice. In co-immunoprecipitation experiments, PMEPA1a associated with the Hippo tumor suppressor kinase LATS1. This interaction led to a proteasomal degradation of LATS1 through recruitment of the ubiquitin ligase, neural precursor cell expressed, developmentally downregulated 4 (NEDD4), which led to silencing of Hippo signaling. Alanine substitution in PMEPA1a at PY motifs resulted in failed LATS1 degradation. Targeting of a downstream component in the Hippo signaling pathway, YAP, with shRNA, interfered with the growth promoting activities of PMEPA1a in vitro and in vivo. In conclusion, the presented work shows that PMEPA1a contributes to glioma progression by a dysregulation of the Hippo signaling pathway and thus represents a promising target for the treatment of gliomas.

Circular RNA PRKCI promotes glioma cell progression by inhibiting microRNA-545

We here tested expression and potential functions of circular RNA PRKCI (circPRKCI) in human glioma. Our results show that circPRKCI is upregulated in human glioma tissues and glioma cells, correlating with downregulation of its potential target, microRNA-545 (miR-545). In A172 and primary human glioma cells, shRNA-mediated silencing of circPRKCI inhibited cancer cell growth, survival, proliferation, and migration. Conversely, ectopic circPRKCI overexpression promoted A172 cell progression. miR-545 is the primary target of circPRKCI in glioma cells. Forced overexpression of miR-545 mimicked circPRKCI shRNA-induced actions, inhibiting glioma cell survival and proliferation. In contrast, miR-545 inhibition, by a lentiviral antagomiR-545 construct, reversed circPRKCI shRNA-induced anti-A172 cell activity. Importantly, neither circPRKCI shRNA nor circPRKCI overexpression was effective in miR-545-knockout (Cas9 method) A172 cells. Importantly, the subcutaneous and orthotopic A172 xenograft growth was significantly inhibited by circPRKCI silencing. Collectively, circPRKCI promotes human glioma cell progression possibly by inhibiting miR-545. Targeting circPRKCI-miR-545 cascade could efficiently inhibit human glioma cells.

RNA splicing factor USP39 promotes glioma progression by inducing TAZ mRNA maturation

Increasing evidence demonstrates that ubiquitin specific protease 39 (USP39) plays an oncogenic role in various human tumors. Here, using expression analysis of the publicly available Oncomine database, clinical glioma patient samples, and glioma cells, we found that USP39 was overexpressed in human gliomas. Knockdown of USP39 in glioma cells demonstrated that the protein promoted cell growth, invasion and migration in vitro and in a tumor model in nude mice. To identify mediators of USP39 growth-promoting properties, we used luciferase reporter constructs under transcriptional control of various promoters specific to seven canonical cancer-associated pathways. Luciferase activity from a synthetic TEAD-dependent YAP/TAZ-responsive reporter, as a direct readout of the Hippo signaling pathway, was decreased by 92% in cells with USP39 knockdown, whereas the luciferase activities from the other six cancer pathways, including MAPK/ERK, MAPK/JNK, NFκB, Notch, TGFβ, and Wnt, remained unchanged. TAZ protein expression however was decreased independent of canonical Hippo signaling. Immunohistochemistry revealed a positive correlation between USP39 and TAZ proteins in orthotopic xenografts derived from modified glioma cells expressing USP39 shRNAs and primary human glioma samples (p < 0.05). Finally, loss of USP39 decreased TAZ pre-mRNA splicing efficiency in glioma cells in vitro, which led to reduced levels of TAZ protein. In summary, USP39 has oncogenic properties that increase TAZ protein levels by inducing maturation of its mRNA. USP39 therefore provides a novel therapeutic target for the treatment of human glioma.

Abstract 1300: Novel thyrointegrin αvβ3 antagonist in the treatment of glioblastoma multiforme

Abstract Background: The proliferative and pro-angiogenic actions mediated by L-thyroxine, pro-inflammatory and all known growth factors in glioblastoma multiforme (GBM) are initiated at cell surface thyrointegrin αvβ3 receptors for thyroid hormone on the extracellular domain of integrin αvβ3. Thyrointegrin αvβ3 receptors are over-expressed on cancer and rapidly dividing blood vessel cells, but quiescent on normal cells. A macromolecule Polyethylene glycol-conjugated bi-TriAzole Tetraiodothyroacetic acid (P-bi-TAT) acts with high affinity (Ki 3.1 nM) and specificity for the thyrointegrin αvβ3 receptors without any significant nuclear translocation. Methods: In the present studies, three primary human GBM cells and U87 glioma cell line were implanted orthotopically or subcutaneously (s.c.) into nude mice that were treated daily for up to 21 days with P-bi-TAT at different doses. Additionally, preclinical Pharmacokinetic and Safety assessments were carried out in multiple species. Results: Pharmacokinetic profiles indicated once-a-day dosing, and safety assessment studies demonstrated high safety and tolerability at 100-fold over the anticipated human equivalent dose. Fluorescence labeled P-bi-TAT administered s.c. demonstrated high biodistribution to GBM tumor in the brain that was comparable to peripherally implanted tumor. P-bi-TAT administered daily for 10-21 days s.c. at 0.3-10 mg/kg resulted in a dose-dependent suppression of GBM tumor growth and viability monitored with IVIS imaging (p &amp;lt;0.001). Histopathological analysis of tumors revealed 95% loss of the vascularity of treated tumors at 10 days (p &amp;lt;0.001) along with extensive cellular necrosis and apoptosis, without intratumoral hemorrhage. GBM tumors had a 97% volume loss and maximal loss of GBM cell viability during a subsequent 22 days off-treatment period (p &amp;lt; 0.001). Genomic micro-array studies with human primary GBM revealed that over 30 pathways relevant to the progression of GBM are modulated by P-bi-TAT. Conclusions: P-bi-TAT is a promising lead clinical candidate effective in the treatment of human GBM. Citation Format: Shaker A. Mousa, Thangirala Sudha, Kavitha Godugu, Mehdi Rajabi, Stewart Sell, Paul J. Davis. Novel thyrointegrin αvβ3 antagonist in the treatment of glioblastoma multiforme [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1300.

Abstract 3414: Identifying dysregulated lncRNAs and miRNAs in low grade glioma: Uncovering signaling pathways and novel therapeutic targets

Abstract A molecular subtype of low grade gliomas (LGG) is characterized by mutations in Alpha-Thalassemia Mental Retardation X-linked (ATRX), TP53 and isocitrate dehydrogenase 1 (IDH1R132H, mIDH1). Our lab has generated a genetically engineered mouse model that harbors the characteristic genetic lesions found in this molecular subtype of LGG. We determined that mouse neurospheres (NS) bearing these mutations showed downregulation of signaling pathways involved in oligodendrocyte differentiation. The production of 2-hydroxyglutarate (2HG) by mIDH1 induces histone and DNA hypermethylation, which has been shown to impair neural precursor cells’ differentiation. We aim to investigate how the presence of mIDH1 impacts the epigenetic regulation of long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and mRNAs in human mutant IDH1 glioma cell cultures obtained from patients at the time of surgery. We hypothesize that the dysregulation/remodeling of lncRNAs, miRNAs and mRNAs contributes to the invasiveness, differentiation status and stemness of glioma cells. Only a handful of lncRNAs have been studied in relation to their role in neural cells’ lineage commitment and glioma stem cells’ biology. We identified 127 differentially expressed (DE) lncRNA (FDR&amp;lt;0.01) in a human primary glioma cell culture SJGBM2, which has a ATRX mutation and was stably-transfected to express mIDH1. Of the 14 DE miRNAs identified, hsa-miR-210-3p and hsa-miR-4461, which have been linked to tumor invasiveness. The results from this work will reveal novel mechanistic pathways by which lncRNA/miRNAs and differentially expressed mRNAs impact downstream signaling pathways in LGG and uncover new therapeutic targets for this molecular glioma subtype. SC is supported by the T32 Cancer Biology Training Grant, the work is supported by grants from NIH/NINDS to MGC and PRL. Citation Format: Stephen Carney, Felipe Nuñez, Pedro R. Lowenstein, Maria G. Castro. Identifying dysregulated lncRNAs and miRNAs in low grade glioma: Uncovering signaling pathways and novel therapeutic targets [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3414.

MicroRNA-4500 inhibits human glioma cell progression by targeting IGF2BP1

Insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) overexpression promotes glioma cell progression. The aim of the current study is to silence IGF2BP1 in glioma cells by the microRNA (miRNA) strategy. The bio-informatic analyses identified that microRNA-4500 (miR-4500) putatively targets 3′-UTR (3′-untranslated region) of IGF2BP1. In A172 cells and primary human glioma cells ectopic overexpression of the wild-type miR-4500 (but not the mutant form) downregulated IGF2BP1 and its target genes (Gli1, IGF2 and c-Myc). Functional studies show that ectopic miR-4500 overexpression inhibited glioma cell growth, survival, proliferation, migration and invasion. Conversely, in A172 cells miR-4500 inhibition, by a lentiviral construct, increased expression of IGF2BP1 and its targets, promoting cell survival, proliferation and migration. Furthermore, IGF2BP1 knockout by the CRISPR/Cas9 method inhibited A172 cell progression. Significantly, miR-4500 overexpression or miR-4500 inhibition was ineffective in IGF2BP1 knockout A172 cells. At last, we show that miR-4500 levels are downregulated in human glioma tissues, correlating with IGF2BP1 upregulation. Together, we conclude that miR-4500 inhibits human glioma cell progression by targeting IGF2BP1.

Expression and activity of the calcitonin receptor family in a sample of primary human high-grade gliomas

BackgroundGlioblastoma (GBM) is the most common and aggressive type of primary brain cancer. With median survival of less than 15 months, identification and validation of new GBM therapeutic targets is of critical importance.ResultsIn this study we tested expression and performed pharmacological characterization of the calcitonin receptor (CTR) as well as other members of the calcitonin family of receptors in high-grade glioma (HGG) cell lines derived from individual patient tumours, cultured in defined conditions.Previous immunohistochemical data demonstrated CTR expression in GBM biopsies and we were able to confirm CALCR (gene encoding CTR) expression. However, as assessed by cAMP accumulation assay, only one of the studied cell lines expressed functional CTR, while the other cell lines have functional CGRP (CLR/RAMP1) receptors. The only CTR-expressing cell line (SB2b) showed modest coupling to the cAMP pathway and no activation of other known CTR signaling pathways, including ERK1/2 and p38 MAP kinases, and Ca2+ mobilization, supportive of low cell surface receptor expression.Exome sequencing data failed to account for the discrepancy between functional data and expression on the cell lines that do not respond to calcitonin(s) with no deleterious non-synonymous polymorphisms detected, suggesting that other factors may be at play, such as alternative splicing or rapid constitutive receptor internalisation.ConclusionsThis study shows that GPCR signaling can display significant variation depending on cellular system used, and effects seen in model recombinant cell lines or tumour cell lines are not always reproduced in a more physiologically relevant system and vice versa.

Polyplexes of Functional PAMAM Dendrimer/Apoptin Gene Induce Apoptosis of Human Primary Glioma Cells In Vitro.

Highly efficient and safe gene delivery has become an important aspect of neuronal gene therapy. We evaluated the ability of polyamidoamine (PAMAM) dendrimer grafted with phenylalanine, histidine, and arginine (PAMAM-FHR), a nonviral gene delivery vector, to deliver a therapeutic, tumor cell-specific killer gene, apoptin, into the human primary glioma cell line GBL-14 and human dermal fibroblasts. We performed a transfection assay using plasmids of luciferase and enhanced green fluorescent protein (EGFP) and assessed cell viability. Both cell lines were treated with complexes of PAMAM-FHR and apoptin after which their intracellular uptake and localization were examined by fluorescence-activated cell sorting (FACS)analysis and confocal laser scanning microscopy. Confocal microscopy showed that the PAMAM-FHR escaped from the endo-lysosome into the cytosol. Cell cycle phase distribution analysis, annexin V staining, and a tetramethylrhodamine ethyl ester (TMRE) assay established that apoptin triggered apoptosis in the GBL-14 cell line but not in normal fibroblasts. These results indicated that the PAMAM-FHR/apoptin complex is an effective gene vehicle for cancer therapy in vitro.

Relationship between expression of XRCC1 and tumor proliferation, migration, invasion, and angiogenesis in glioma

Recently, XRCC1 polymorphisms were reported to be associated with glioma in Chinese population. However, only a few studies reported on the XRCC1 expression, and cancer progression. In this study, we investigated whether XRCC1 plays a role in glioma pathogenesis. Using the tissue microarray technology, we found that XRCC1 expression is significantly decreased in glioma compared with tumor adjacent normal brain tissue (P < 0.01, χ2 test) and reduced XRCC1 staining was associated with WHO stages (P < 0.05, χ2 test). The mRNA and protein levels of XRCC1 were significantly downregulated in human primary glioma tissues (P < 0.001, χ2 test). We also found that XRCC1 was significantly decreased in glioma cell lines compared to normal human astrocytes (P < 0.01, χ2 test). Overexpression of XRCC1 dramatically reduced the proliferation and caused cessation of cell cycle. The reduced cell proliferation is due to G1 phase arrest as cyclin D1 is diminished whereas p16 is upregulated. We further demonstrated that XRCC1 overexpression suppressed the glioma cell migration and invasion abilities by targeting MMP-2. In addition, we also found that overexpression of XRCC1 sharply inhibited angiogenesis, which correlated with down-regulation of VEGF. The data indicate that XRCC1 may be a tumor suppressor involved in the progression of glioma.

HIV-1 Envelope Protein gp120 Promotes Proliferation and the Activation of Glycolysis in Glioma Cell.

Patients infected with human immunodeficiency virus (HIV) are more prone to developing cancers, including glioblastomas (GBMs). The median survival for HIV positive GBM patients is significantly shorter than for those who are uninfected, despite the fact that they receive the same treatments. The nature of the GBM–HIV association remains poorly understood. In this study, we analyzed the effect of the HIV envelope glycoprotein gp120 on GBM cell proliferation. Specifically, we performed cell cycle, western blot, protein synthesis and metabolomics analysis as well as ATP production and oxygen consumption assays to evaluate proliferation and metabolic pathways in primary human glioma cell line, U87, A172 cells and in the HIVgp120tg/GL261 mouse model. Glioma cells treated with gp120 (100 ng/mL for 7–10 days) showed higher proliferation rates and upregulation in the expression of enolase 2, hexokinase and glyceraldehyde-3-phosphate dehydrogenase when compared to untreated cells. Furthermore, we detected an increase in the activity of pyruvate kinase and a higher glycolytic index in gp120 treated cells. Gp120 treated GBM cells also showed heightened lipid and protein synthesis. Overall, we demonstrate that in glioma cells, the HIV envelope glycoprotein promotes proliferation and activation of glycolysis resulting in increased protein and lipid synthesis.

The p75 neurotrophin receptor enhances HIF-dependent signaling in glioma

Tumor hypoxia is associated with several features of aggressive glioma growth, including migration, invasion, and stemness. Most of the cellular adaptation to hypoxia is mediated by the hypoxia-inducible factors HIF-1α and HIF-2α, but regulation of these factors by both oxygen-dependent and –independent mechanisms in brain tumors is only partially understood. Here, we show that the p75 neurotrophin receptor (p75NTR) is stabilized at hypoxia in murine glioma in vivo, as well as in primary human glioma cultures in vitro. Expression of p75NTR resulted in increased stabilization of HIF-1α and HIF-2α, and RNAi or pharmacologic targeting of p75NTR diminished HIF stabilization and HIF-dependent signaling at hypoxia. Consequentially, p75NTR inhibition resulted in decreased migration, invasion, and stemness in response to hypoxia, suggesting that p75NTR is a central regulator of hypoxia-induced glioma aggressiveness. Together, our findings support the literature that identifies p75NTR as a potential therapeutic target in brain tumors.

An adherent tissue-inspired hydrogel delivery vehicle utilised in primary human glioma models

A physical hydrogel cross-linked via the host-guest interactions of cucurbit[8]uril and utilised as an implantable drug-delivery vehicle for the brain is described herein. Constructed from hyaluronic acid, this hydrogel is biocompatible and has a high water content of 98%. The mechanical properties have been characterised by rheology and compared with the modulus of human brain tissue demonstrating the production of a soft material that can be moulded into the cavity it is implanted into following surgical resection. Furthermore, effective delivery of therapeutic compounds and antibodies to primary human glioblastoma cell lines is showcased by a variety of in vitro and ex vivo viability and immunocytochemistry based assays.