Malignant Progression Of Glioma Research Articles

Clinical and Biological Significances of a Methyltransferase-Related Signature in Diffuse Glioma.

Methylation of DNA, RNA or protein is a reversible modification. The proteins and genes that regulate this modification can be a candidate target for tumor therapy. However, the characteristics of methyltransferase related genes in glioma remain obscure. In this study, we systematically analyzed the relationship between methyltransferase-related genes expression profiles and outcomes in glioma patients based on The Cancer Genome Atlas and Chinese Glioma Genome Atlas RNA sequencing datasets. Consensus clustering identified two robust groups with significantly different pathological features and prognosis. Then a methyltransferase-related risk signature was built by a Cox proportional hazards model with elastic net penalty. Moreover, the risk score is associated with patients' clinical and molecular features and can be used as an independent prognostic indicator for patients with glioma. Furthermore, genes associated with the high-risk group were involved in various aspects of the malignant progression of glioma via Gene Ontology analysis and Gene Set Enrichment Analysis. In summary, our study identified a methyltransferase-related risk signature for predicting the prognosis of gliomas.

Protein disulphide isomerase can predict the clinical prognostic value and contribute to malignant progression in gliomas.

Increasing evidence from structural and functional studies has indicated that protein disulphide isomerase (PDI) has a critical role in the proliferation, survival and metastasis of several types of cancer. However, the molecular mechanisms through which PDI contributes to glioma remain unclear. Here, we aimed to investigate whether the differential expression of 17 PDI family members was closely related to the different clinicopathological features in gliomas from The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas data sets. Additionally, four subgroups of gliomas (cluster 1/2/3/4) were identified based on consensus clustering of the PDI gene family. These findings not only demonstrated that a poorer prognosis, higher WHO grade, lower frequency of isocitrate dehydrogenase mutation and higher 1p/19q non‐codeletion status were significantly correlated with cluster 4 compared with the other clusters, but also indicated that the malignant progression of glioma was closely correlated with the expression of PDI family members. Moreover, we also constructed an independent prognostic marker that can predict the clinicopathological features of gliomas. Overall, the results indicated that PDI family members may serve as possible diagnostic markers in gliomas.

Transformation Foci in IDH1-mutated Gliomas Show STAT3 Phosphorylation and Downregulate the Metabolic Enzyme ETNPPL, a Negative Regulator of Glioma Growth

IDH1-mutated gliomas are slow-growing brain tumours which progress into high-grade gliomas. The early molecular events causing this progression are ill-defined. Previous studies revealed that 20% of these tumours already have transformation foci. These foci offer opportunities to better understand malignant progression. We used immunohistochemistry and high throughput RNA profiling to characterize foci cells. These have higher pSTAT3 staining revealing activation of JAK/STAT signaling. They downregulate RNAs involved in Wnt signaling (DAAM2, SFRP2), EGFR signaling (MLC1), cytoskeleton and cell-cell communication (EZR, GJA1). In addition, foci cells show reduced levels of RNA coding for Ethanolamine-Phosphate Phospho-Lyase (ETNPPL/AGXT2L1), a lipid metabolism enzyme. ETNPPL is involved in the catabolism of phosphoethanolamine implicated in membrane synthesis. We detected ETNPPL protein in glioma cells as well as in astrocytes in the human brain. Its nuclear localization suggests additional roles for this enzyme. ETNPPL expression is inversely correlated to glioma grade and we found no ETNPPL protein in glioblastomas. Overexpression of ETNPPL reduces the growth of glioma stem cells indicating that this enzyme opposes gliomagenesis. Collectively, these results suggest that a combined alteration in membrane lipid metabolism and STAT3 pathway promotes IDH1-mutated glioma malignant progression.

Elevated expression of DOK3 indicates high suppressive immune cell infiltration and unfavorable prognosis of gliomas

Docking protein 3 has been implicated in immune response, including interferon-β production in macrophage and plasma cell differentiation. And its importance in lung adenocarcinoma has been reported. However, studies about its role in gliomas are rare. In this study, we explored the clinical and prognostic characteristics of DOK3 expression in 921 glioma samples. Kaplan-Meier survival analysis and Cox regression analysis verified the independent unfavorable prognostic value and high prognostic accuracy of DOK3 expression for overall survival. Functional analysis with Database for Annotation, Visualization and Integrated Discovery (DAVID) and Gene Set Enrichment Analysis (GSEA) implied the involvement of DOK3 in immune related responses. Immune cell infiltration analysis with online tools, CIBERSORT and EPIC, showed that samples with higher DOK3 expression were infiltrated with much more macrophages. DOK3 was also found to be strongly positively correlated with marker genes of tumor-associated macrophages and M2 macrophages, not M1. Results of immunohistochemical staining also demonstrated that samples with higher DOK3 expression level were infiltrated with more microglia/macrophages and immunosuppressive M2 macrophages. In summary, our results demonstrated the correlation between high DOK3 expression level and malignant progression of gliomas, and the possible involvement of DOK3 in immunosuppressive responses in gliomas.

Hypoxia-induced lncRNA PDIA3P1 promotes mesenchymal transition via sponging of miR-124-3p in glioma

Hypoxia is a critical factor in the malignant progression of glioma, especially for the highly-invasive mesenchymal (MES) subtype. But the detailed mechanisms in hypoxia-induced glioma MES transition remain elusive. Pseudogenes, once considered to be non-functional relics of evolution, are emerging as a critical factor in human tumorigenesis and progression. Here, we investigated the clinical significance, biological function, and mechanisms of protein disulfide isomerase family A member 3 pseudogene 1 (PDIA3P1) in hypoxia-induced glioma MES transition. In this study, we found that PDIA3P1 expression was closely related to tumor degree, transcriptome subtype, and prognosis in glioma patients. Enrichment analysis found that high PDIA3P1 expression was associated with epithelial-mesenchymal transition, extracellular matrix (ECM) disassembly, and angiogenesis. In vitro study revealed that overexpression of PDIA3P1 enhanced the migration and invasion capacity of glioma cells, while knockdown of PDIA3P1 induced the opposite effect. Further studies revealed that PDIA3P1 functions as a ceRNA, sponging miR-124-3p to modulate RELA expression and activate the downstream NF-κB pathway, thus promoting the MES transition of glioma cells. In addition, Hypoxia Inducible Factor 1 was confirmed to directly bind to the PDIA3P1 promotor region and activate its transcription. In conclusion, PDIA3P1 is a crucial link between hypoxia and glioma MES transition through the PDIA3P1-miR-124-3p-RELA axis, which may serve as a prognostic indicator and potential therapeutic target for glioma treatment.

B7-H3 Regulates Glioma Growth and Cell Invasion Through a JAK2/STAT3/Slug-Dependent Signaling Pathway.

PurposeThe aim of this study was to explore the potential role of B7-H3 in malignant glioma progression and identify an innovative approach in clinical glioma therapy.MethodsThe protein expression of B7-H3 in high- and low-grade tumor tissues from glioma patients was assessed by immunohistochemistry. The proliferative and invasive ability of B7-H3-overexpressing or knockout glioma cells was analyzed in vitro and in vivo by CCK-8 assay and an orthotopic mouse glioma model, respectively. Activation of the JAK2/STAT3/Slug signaling pathway and epithelial–mesenchymal transition (EMT) was examined by Western blotting and immunofluorescence. The anticancer effects of napabucasin (NAP) and temozolomide (TMZ) were analyzed in an orthotopic mouse glioma model.ResultsThe expression of B7-H3 was higher in high-grade than in low-grade tumor tissues from glioma patients. In line with this, overexpression of B7-H3 enhanced glioma cell proliferation, induced sustained glioma growth, and promoted glioma cell invasion in vitro and in vivo. Moreover, these effects were mediated through the activation of the JAK2/STAT3/Slug signaling pathway in B7-H3 overexpression glioma cells. We also found that B7-H3 induced EMT processes through downregulation of E-cadherin and upregulation of MMP-2/-9 expression, resulting in enhanced invasion of glioma cells. Finally, we show that the combination of NAP and TMZ significantly suppressed glioma growth and glioma cell invasion, both in vitro and in vivo.ConclusionB7-H3 overexpression facilitated sustained glioma growth and promoted glioma cell invasion through a JAK2/STAT3/Slug-dependent signaling pathway. Application of the STAT3 inhibitor NAP significantly suppressed glioma growth and invasion, and has potential as a therapeutic strategy for the treatment of glioma.

Genomics and Prognosis Analysis of Epithelial-Mesenchymal Transition in Glioma.

Background: Epithelial-mesenchymal transition (EMT) is regulated by induction factors, transcription factor families and an array of signaling pathways genes, and has been implicated in the invasion and progression of gliomas.Methods: We obtained the Clinicopathological data sets from Chinese Glioma Genome Atlas (CGGA). The “limma” package was used to analyze the expression of EMT-related genes in gliomas with different pathological characteristics. We used the “ConsensusClusterPlus” package to divide gliomas into two groups to study their correlation with glioma malignancy. The least absolute shrinkage and selection operator (LASSO) Cox regression was applied to select seven prognosis-associated genes to build the risk signature, and the coefficients obtained from the LASSO algorithm were used to calculate the risk score which we applied to determine the prognostic value of the risk signature. Univariate and multivariate Cox regression analyses were used to determine whether the risk signature is an independent prognostic indicator.Results: We analyzed the differentially expressed 22 common epithelial-mesenchymal transition-associated genes in 508 gliomas graded by different clinicopathological features. Two glioma subgroups (EM1/2) were identified by consistent clustering of the proteins, of which the EM1 subgroup had a better prognosis than the EM2 subgroup, and the EM2 group was associated with cancer migration and proliferation. Significant enrichment analysis revealed that EMT-related transcriptional regulators and signaling pathways genes were highly related to glioma malignancies. Seven EMT-related genes were used to derive risk scores, which served as independent prognostic markers and prediction factors for the clinicopathological features of glioma. And we found the overall survival (OS) was significantly different between the low- and high-risk groups, the ROC curve indicated that the risk score can predict survival rates for glioma patients.Conclusion: EMT-related induction factors, transcriptional regulators and signaling pathways genes are important players in the malignant progression of glioma and may help in decision making regarding the choice of prognosis assessment and provide us clues to understand EMT epigenetic modification in glioma.

Dual functionalized brain-targeting nanoinhibitors restrain temozolomide-resistant glioma via attenuating EGFR and MET signaling pathways

Activation of receptor tyrosine kinase (RTK) protein is frequently observed in malignant progression of gliomas. In this study, the crosstalk activation of epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor (MET) signaling pathways is demonstrated to contribute to temozolomide (TMZ) resistance, resulting in an unfavorable prognosis for patients with glioblastoma. To simultaneously mitigate EGFR and MET activation, a dual functionalized brain-targeting nanoinhibitor, BIP-MPC-NP, is developed by conjugating Inherbin3 and cMBP on the surface of NHS-PEG8-Mal modified MPC-nanoparticles. In the presence of BIP-MPC-NP, DNA damage repair is attenuated and TMZ sensitivity is enhanced via the down-regulation of E2F1 mediated by TTP in TMZ resistant glioma. In vivo magnetic resonance imaging (MRI) shows a significant repression in tumor growth and a prolonged survival of mice after injection of the BIP-MPC-NP and TMZ. These results demonstrate the promise of this nanoinhibitor as a feasible strategy overcoming TMZ resistance in glioma.

Loss of cytoskeleton protein ADD3 promotes tumor growth and angiogenesis in glioblastoma multiforme

Adducin 3 (ADD3) is a crucial assembly factor in the actin cytoskeleton and has been found to be aberrantly expressed in various cancers, including glioblastoma multiforme (GBM). It has previously been studied in array-based studies with controversial findings as to its functional role in glioma. In microarray analyses of 452 glioma specimens, we found significant downregulation of ADD3 in GBM, but not in less malignant gliomas, compared to normal brain tissue, which suggests that its downregulation might underlie critical events during malignant progression. We also found that ADD3 was functionally dependent on cell-matrix interaction. In our in vivo study, the proliferative and angiogenic capacity of ADD3-depleted GBM cells was promoted, possibly through PCNA, while p53 and p21 expression was suppressed, and pro-angiogenic signals were induced through VEGF-VEGFR-2-mediated activation in endothelial cells. With correlative in vitro, in vivo, and clinical data, we provide compelling evidence on the putative tumor-suppressive role of ADD3 in modulating GBM growth and angiogenesis. As a preclinical study, our research offers a better understanding of the pathogenesis of glioma malignant progression for the benefit of future investigations.

RGS16 Promotes Glioma Progression and Serves as a Prognostic Factor

RGS protein family members have recently became new potentially promising therapeutic targets in many cancers. However, as a key member of RGS family, RGS16 has seldom been studied in glioma. The present study was designed to investigate the prognostic value and biological function of RGS16 based on large-scale databases and functional assays in vitro. Here we performed comprehensive analysis for the expression characteristic of RGS16 in Chinese Glioma Genome Atlas (CGGA) microarray database with 301 patients, and validated in The Cancer Genome Atlas (TCGA) microarray and RNA sequencing database. We found that the expression of RGS16 was positively related to the grade of glioma. High-level of RGS16 commonly gathered in glioma of mesenchymal subtype and wild-type IDH1. Moreover, higher expression level of RGS16 was found to be significantly correlated with poor prognosis. The univariate and multivariate Cox regression analysis and ROC curve showed that RGS16 was an independent prognostic factor for glioma patients. Gene ontology analysis, gene set enrichment analysis and gene set variation analysis suggested that the overexpression of RGS16 tightly related to cell proliferation, migration, epithelial-mesenchymal transition (EMT), immune and inflammatory response of glioma. Additionally, RGS16 was involved in immune functions via modulating T-lymphocyte-mediated anti-tumor immunity. Knockdown of RGS16 in glioma cell lines also showed that RGS16 promoted the malignant progress of glioma cell lines. These results suggested that RGS16 closely related to malignant progression of glioma and serves as an independent prognostic factor, especially in GBM patients. Meanwhile, RGS16 was a potential target for immunotherapy of glioma. Funding Statement: This work was supported by grants from National Natural Science Foundation of China (81972816, 81702460 and 81802994), Beijing Natural Science Foundation (7192057) and Beijing Young Crops Project QML20190506). Declaration of Interests: No potential conflicts of interest were disclosed. Ethics Approval Statement: This study was approved by the institutional review board (IRB) of Beijing Tiantan Hospital and informed consent was obtained from all individual participants for CGGA project in this study.

Circ_0005075 stimulates the proliferation and metastasis of glioma via downregulating SIRT1.

The aim of this study was to uncover the potential influence of circ_0005075 on the malignant progression of glioma and the underlying mechanism. Circ_0005075 level in glioma tissues and cell lines was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The relation between circ_0005075 expression and metastasis of glioma patients was analyzed. Prognostic potential of circ_0005075 in glioma was assessed by calculating overall survival (OS) and progression-free survival (PFS). After knockdown or overexpression of circ_0005075, changes in the viability, migration, and wound closure percentage of T98-G and U87 cells were examined, respectively. Subsequently, expression pattern and prognostic value of SIRT1 in glioma patients were determined. Furthermore, the involvement of SIRT1 in glioma progression affected by circ_0005075 was evaluated through rescue experiments. Circ_0005075 was significantly up-regulated in glioma tissues and cell lines. Meanwhile, its expression level was significantly higher in glioma patients with lymphatic metastasis or distant metastasis when compared with those with negative metastasis. OS and PFS were both remarkably worse in glioma patients with high expression level of circ_0005075. Knockdown of circ_0005075 decreased the viability, migration, and wound closure percentage of T98-G cells. However, overexpression of circ_0005075 in U87 cells yielded the opposite trends. SIRT1 expression level was negatively regulated by circ_0005075 in glioma. QRT-PCR results demonstrated that SIRT1 was significantly down-regulated in glioma tissues and cell lines. High level of SIRT1 predicted better prognosis of glioma patients. Rescue experiments confirmed that SIRT1 was responsible for the regulatory role of circ_0005075 in the malignant progression of glioma. Circ_0005075 is up-regulated in glioma tissues and correlated with distant metastasis and poor prognosis of glioma patients. Furthermore, it aggravates the malignant progression of glioma by down-regulating SIRT1.

Circ-DONSON promotes malignant progression of glioma through modulating FOXO3.

The aim of this study was to investigate the expression level of circ-DONSON in glioma and to explore its effect on glioma metastasis and the underlying mechanism. Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was performed to examine circ-DONSON expression in 40 paired glioma tumor tissues and adjacent tissues. Meanwhile, the relation between circ-DONSON level and clinical parameters of glioma and the prognosis of patients was analyzed. The expression of circ-DONSON in glioma cell lines was analyzed by qRT-PCR as well. In addition, circs-DONSON silencing model was constructed in glioma cell lines. Cell counting kit-8 (CCK-8), cell scratch, and transwell migration assays were performed to investigate the effect of circ-DONSON on biological functions of glioma cells. Finally, the interplay between FOXO3 and circ-DONSON was explored. QRT-PCR results revealed that the expression level of circ-DONSON in glioma tumor tissues was remarkably higher than that of adjacent tissues, and the difference was statistically significant (p<0.05). Compared with patients with low expression of circ-DONSON, significantly higher prevalence of lymph node or distant metastasis and worse prognosis were observed in patients with high expression of circ-DONSON (p<0.05). The proliferation and migration abilities of glioma cells in circ-DONSON silenced group were remarkably suppressed when compared with NC group (p<0.05). Additionally, FOXO3 expression was remarkably down-regulated in glioma cell lines and tissues. FOXO3 expression was negatively correlated with circ-DONSON expression. In addition, cell reverse experiment demonstrated that circ-DONSON and FOXO3 can regulate each other, thereby together affecting the malignant progression of glioma. Circ-DONSON was remarkably associated with lymph node or distant metastasis, as well as poor prognosis of patients with glioma. Furthermore, it promoted the metastasis of glioma cells via regulating FOXO3.

Connexin43 peptide, TAT-Cx43266-283, selectively targets glioma cells, impairs malignant growth, and enhances survival in mouse models in vivo.

BackgroundMalignant gliomas are the most frequent primary brain tumors and remain among the most incurable cancers. Although the role of the gap junction protein, connexin43 (Cx43), has been deeply investigated in malignant gliomas, no compounds have been reported with the ability to recapitulate the tumor suppressor properties of this protein in in vivo glioma models.MethodsTAT-Cx43266–283 a cell-penetrating peptide which mimics the effect of Cx43 on c-Src inhibition, was studied in orthotopic immunocompetent and immunosuppressed models of glioma. The effects of this peptide in brain cells were also analyzed.ResultsWhile glioma stem cell malignant features were strongly affected by TAT-Cx43266–283, these properties were not significantly modified in neurons and astrocytes. Intraperitoneally administered TAT-Cx43266–283 decreased the invasion of intracranial tumors generated by GL261 mouse glioma cells in immunocompetent mice. When human glioma stem cells were intracranially injected with TAT-Cx43266–283 into immunodeficient mice, there was reduced expression of the stemness markers nestin and Sox2 in human glioma cells at 7 days post-implantation. Consistent with the role of Sox2 as a transcription factor required for tumorigenicity, TAT-Cx43266–283 reduced the number and stemness of human glioma cells at 30 days post-implantation. Furthermore, TAT-Cx43266–283 enhanced the survival of immunocompetent mice bearing gliomas derived from murine glioma stem cells.ConclusionTAT-Cx43266–283 reduces the growth, invasion, and progression of malignant gliomas and enhances the survival of glioma-bearing mice without exerting toxicity in endogenous brain cells, which suggests that this peptide could be considered as a new clinical therapy for high-grade gliomas.

SKA1 promotes malignant phenotype and progression of glioma via multiple signaling pathways

BackgroundSpindle and kinetochore associated protein 1 (SKA1) is a protein involved in chromosome congression and mitosis. It has been found to be upregulated and oncogenic in several human cancers. Herein, we investigated the precise role of SKA1 in the progression and malignant phenotype of human glioma.MethodsBioinformatic analysis was carried out based on the RNA-seq data and corresponding clinical data from GEO, TCGA and CGGA databases. Western blot was performed to analyze the expression of SKA1 in clinical samples and signaling pathway proteins in glioma cells, respectively. CCK8 assay, colony forming assay and EdU assay were performed to assess the cell viability. Cell migration and invasion assays were also performed. Moreover, xenograft model was established and the expression of SKA1 was assessed in the xenograft by immunohistochemistry.ResultsSKA1 expression is positively correlated with glioma grade and could be a promising biomarker for GBM. Moreover, overexpression of SKA1 may lead to poor prognosis in glioma. Downregulation of SKA1 attenuated cell viability, migration, and invasion in U251, U87, LN229 and T98 cells. Furthermore, GSEA analysis demonstrated that SKA1 was involved in the cell cycle, EMT pathway as well as Wnt/β-catenin signaling pathway, which were then confirmed with Western blot analysis.ConclusionSKA1 promotes malignant phenotype and progression of glioma via multiple pathways, including cell cycle, EMT, Wnt/β-catenin signaling pathway. Therefore, SKA1 could be a promising therapeutic target for the treatment of human gliomas.

MAGI1 Inhibits the Proliferation, Migration and Invasion of Glioma Cells.

BackgroundMembrane-associated guanylate kinase inverted repeat member 1 (MAGI1) acts as a tumor suppressor in a variety of tumors; however, its expression and biological function in glioma are still unknown.MethodsMAGI1 expression in glioma was examined by immunohistochemistry. In addition, overexpression of MAGI1 in U87 and U373 cells, colony formation and MTT assays were used to evaluate cell proliferation, Transwell assays to determine cell migration and invasion, and a xenograft model established using U87 cells to evaluate the effect of MAGI1 overexpression in vivo. Western blot assays were used to analyze the Akt, MMP2, MMP9 and E-cadherin/N-cadherin/vimentin pathway changes after overexpression of MAGI1.ResultsWe demonstrated that MAGI1 was expressed at low levels in glioma. Low MAGI1 expression was positively correlated with the malignant progression of glioma and indicated a poor prognosis. Moreover, we found that overexpressed MAGI1 inhibited the proliferation, migration and invasion of glioma cells by regulating cell growth and EMT through Akt, MMP2, MMP9 and the E-cadherin/N-cadherin/vimentin pathway.ConclusionThese findings demonstrate a novel function of MAGI1 in glioma progression and suggest that MAGI1 might be a target for the diagnosis and treatment of glioma.

Role of Erythropoietin in Cerebral Glioma: An Innovative Target in Neuro-Oncology

Erythropoietin (EPO) is a cytokine primarily involved in the regulation of erythropoiesis. In response to hypoxia-ischemia, hypoxia-inducible factor 1 induces EPO production, which, in turn, inhibits apoptosis of erythroid progenitor cells. By the same mechanism and acting through other signaling pathways, EPO exerts neuroprotective effects. Increased resistance to hypoxia and decreased apoptosis are thought to be important mechanisms for tumor progression, including malignant glioma. Because recent studies have demonstrated that EPO and its receptor (EPOR) are expressed in several tumors and can promote tumor growth, in the present study, we investigated EPO and EPOR expression in human glioma and the effect of EPO administration in a rat model of glioma implantation. Using Western blotting and immunohistochemical analysis, we examined the expression of EPO, EPOR, platelet endothelial cell adhesion molecule, and Ki-67 in human glioma specimens and experimentally induced glioma in rats. In the experimental setting, a daily dose of recombinant human EPO (rHuEPO) or saline solution were administered for 21 days in Fischer rats subjected to 9L cell line implantation. In both human and animal specimens, we found an increase in EPOR expression as long as the lesion presented with an increasing malignant pattern. A significant direct correlation was found between the expression of EPOR and Ki-67 and EPOR and platelet endothelial cell adhesion molecule in low- and high-grade gliomas. The rats treated with rHuEPO presented with significantly larger tumor spread compared with the saline-treated rats. The results of our study have shown that the EPO/EPOR complex might play a significant role in the aggressive behavior of high-grade gliomas. The larger tumor spread in rHuEPO-treated rats suggests a feasible role for EPO in the aggressiveness and progression of malignant glioma.

Hypoxia induced LBH overexpression accelerates malignant progression in glioma.

Hypoxia induced LBH overexpression accelerates malignant progression in glioma.

Identification of novel LncRNA targeting Smad2/PKCα signal pathway to negatively regulate malignant progression of glioblastoma

Glioblastoma multiforme (GBM) is a highly proliferative cancer with generally poor prognosis and accumulating evidence has highlighted the potential of long noncoding RNAs (lncRNAs) in the biological behaviors of glioma cells. This study focused on the identification of lncRNAs to identify targets for possible GBM prognosis. Microarray expression profiling found that 1,759 lncRNAs and 3,026 messenger RNAs (mRNAs) were upregulated, and 1932s lncRNA and 2,979 mRNAs were downregulated in GBM. Bioinformatics analysis and experimental verification identified TCONS_00020456 (TCON) for further analysis. In situ hybridization, along with immunohistochemical and receiver operating characteristic analysis determined TCON (truncation value = 3.5) as highly sensitive and specific in GBM. Grade IV patients with glioma life span with different lncRNA staining scores were analyzed. TCON staining scores below 3.5 indicated poor prognosis (life span ranging from 0.25 to 7 months), even if the glioma was surgically removed. TCON decreased significantly in GBM, and showed a coexpressional relationship with Smad2 and protein kinase C α (PKCα). Overexpression of TCON reduced the proliferation on one hand and migration, invasion on the other. TCON also inhibited epithelial–mesenchymal transformation and glioma progression in vivo, based on a nude mouse tumorigenicity assay. In addition, we predicted a potential binding site and intersection that microRNAs targeting Smad2, PKCα, and TCON through RACE pretest and bioinformatics analysis. Taken together, TCON, regarded as oncosuppressor, targeting the Smad2/PKCα axis plays a novel role in inhibiting the malignant progression of glioma. Moreover, it also demonstrates that the level of TCON can be used as a prognostic and diagnostic biomarker for GBM.

43P - XAF1 enhances temozolomide induced autophagic cell death through AMPK signaling pathway

BackgroundXIAP-associated factor 1 (XAF1) is a pro-apoptotic tumor suppressor whose expression is inactivated in many human malignancies. To explore the XAF1’s candidacy for a suppressor in the pathogenesis of human glioma, we investigated its expression and function in tumor cell lines and tissues. MethodsExpression study was performed using quantitative RT-PCR and immunoblot assays. Functional interplay between XAF1 and AMPK was determined by gene transfection, siRNA-mediated depletion. ResultsXIAP-associated factor 1 (XAF1) is a pro-apoptotic tumor suppressor whose expression is inactivated in many human malignancies. In this study, we explored the XAF1’s candidacy for a suppressor in human glioma pathogenesis. XAF1 reduction is more common in high grade tumors versus low grade tumors and tightly associated with aberrant hypermethylation at 7 CpG sites in the 5’ proximal region of the promoter. XAF1 expression decreases proliferation and colony-forming ability of glioma cells while its depletion enhances cellular resistance to genotoxic drugs, such as temozolomide (TMZ), etoposide and cisplatin. The XAF1 promoter is activated in response to TMZ through JNK-IRF-1 signaling and its activation greatly increases cellular response to TMZ-induced cell death. Furthermore, XAF1 promotes autophagic cell death (ACD) by activating AMP-activated protein kinase (AMPK) in a XIAP-independent manner. Both AMPK-activating and ACD-inducing effects of XAF1 are linked to its activity to decrease intracellular ATP level, oxygen consumption, and mitochondrial membrane potential. XAF1 proteins translocate to the mitochondria and the zinc finger (ZF) 6 domain is essential for its mitochondrial distribution. Consistently, a mutant XAF1 lacking the ZF6 fails to decrease ATP level, activate AMPK, and trigger AMPK-mediated autophagic cell death. Collectively, this study demonstrates that epigenetic inactivation of XAF1 contributes to the malignant progression of human glioma by rendering tumor cells a survival advantage via the attenuation of AMPK signaling. ConclusionsEpigenetic inactivation of XAF1 contributes to the malignant progression of human glioma by rendering tumor cells a survival advantage via the attenuation of AMPK signaling. Legal entity responsible for the studyThe authors. FundingNational Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2018R1D1A1B07041512). DisclosureAll authors have declared no conflicts of interest.

LncRNA SAMD12-AS1 down-regulates P53 to promote malignant progression of glioma.

To study the expression level of long non-coding RNA (LncRNA) SAMD12-AS1 in glioma and its influence on the invasive ability of glioma cells; meanwhile, the regulation mechanism of LncRNA SAMD12-AS1 promoting the development of glioma was further explored. The expression level of SAMD12-AS1 in 40 pairs of tumor tissue specimens and paracancerous ones collected from glioma patients were examined through Real Time quantitative-Polymerase Chain Reaction (qRT-PCR) method, and the interplay between SAMD12-AS1 expression and clinical indicators of glioma patients was also analyzed. Meanwhile, the expression of SAMD12-AS1 in glioma cell lines was further verified by qRT-PCR. In addition, SAMD12-AS1 knockdown model was constructed using glioma cell lines (T98-G and U87). Cell Counting Kit-8 (CCK-8), cell wound healing test, and transwell assays were conducted to examine the impact of SAMD12-AS on glioma cell functions. Additionally, whether it exerted its biological characteristics through P53 was finally explored. qPCR results in the study revealed that SAMD12-AS1 expression in tumor tissue specimens of glioma patients was remarkably higher than that in the adjacent ones, and the difference was statistically significant. Compared with patients with low expression of SAMD12-AS1, patients with high expression of SAMD1-AS1 had a higher incidence of lymph node or distant metastasis. In addition, compared to the NC group, knocking down SAMD12-AS1 markedly attenuated the proliferation rate, as well as the invasiveness and migration ability of glioma cells. Subsequently, in glioma tissues, it was verified that P53 expression was remarkably decreased and negatively correlated with SAMD12-AS1. Finally, cell recovery experiment also demonstrated that there may exist a mutual regulation between SAMD12-AS1 and P53, which then together affected the malignant progression of glioma. LncRNA SAMD12-AS1 may accelerate the invasion and migratory capacities of glioma cells by modulating P53, and its expression was confirmed to be significantly relevant to the incidence of lymph node or distant metastasis.