Integrative transcriptome analysis identified a BMP signaling pathway-regulated lncRNA AC068643.1 in IDH mutant and wild-type glioblastomas.

Glioblastomas (GBMs) are classified into isocitrate dehydrogenase (IDH) mutant (IDH MT) and wild-type (IDH WT) subtypes, and each is associated with distinct tumor behavior and prognosis. The present study aimed to investigate differentially expressed long non-coding (lnc)RNAs and mRNAs between IDH MT and IDH WT GBMs, as well as to explore the interaction and potential functions of these RNAs. A total of 132 GBM samples with RNA profiling data (10 IDH MT and 122 IDH WT cases) were obtained from The Cancer Genome Atlas, and 62/78 and 142/219 up/downregulated lncRNAs and mRNAs between IDH MT and IDH WT GBMs were identified, respectively. Multivariate Cox analysis of the dysregulated lncRNAs/mRNAs identified three-lncRNA and fifteen-mRNA signatures with independent prognostic value, indicating that these RNAs may serve roles in determining distinct tumor behaviors and prognosis of patients with IDH MT/WT GBMs. Functional analysis of the three lncRNAs revealed that they were primarily associated with cell stemness or differentiation. Pearson's correlation analysis revealed that the protective lncRNA AC068643.1 was significantly positively correlated with two key bone morphogenetic protein (BMP) signaling-associated mRNAs, Bone morphogenetic protein 2 (BMP2) and Myostatin (MSTN), from the 15 mRNAs. Further in vitro studies demonstrated that BMP2 and MSTN directly stimulated AC068643.1 expression. In conclusion, the present study identified a BMP signaling pathway-regulated lncRNA AC068643.1, which may contribute to the different tumor behaviors observed between IDH MT and IDH WT GBMs.

Bortezomib inhibits growth and sensitizes glioma to temozolomide (TMZ) via down-regulating the FOXM1-Survivin axis.

BACKGROUND: High-grade glioma (HGG) is a fatal human cancer. Bortezomib, a proteasome inhibitor, has been approved for the treatment of multiple myeloma but its use in glioma awaits further investigation. This study aimed to explore the chemotherapeutic effect and the underlying mechanism of bortezomib on gliomas. METHODS: U251 and U87 cell viability and proliferation were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, tumor cell spheroid growth, and colony formation assay. Cell apoptosis and cell cycle were detected by flow cytometry. Temozolomide (TMZ)-insensitive cell lines were induced by long-term TMZ treatment, and cells with stem cell characteristics were enriched with stem cell culture medium. The mRNA levels of interested genes were measured via reverse transcription-quantitative polymerase chain reaction, and protein levels were determined via Western blotting/immunofluorescent staining in cell lines and immunohistochemical staining in paraffin-embedded sections. Via inoculating U87 cells subcutaneously, glioma xenograft models in nude mice were established for drug experiments. Patient survival data were analyzed using the Kaplan-Meier method. RESULTS: Bortezomib inhibited the viability and proliferation of U251 and U87 cells in a dose- and time-dependent manner by inducing apoptosis and cell cycle arrest. Bortezomib also significantly inhibited the spheroid growth, colony formation, and stem-like cell proliferation of U251 and U87 cells. When administrated in combination, bortezomib showed synergistic effect with TMZ in vitro and sensitized glioma to TMZ treatment both in vitro and in vivo. Bortezomib reduced both the mRNA and protein levels of Forkhead Box M1 (FOXM1) and its target gene Survivin. The FOXM1-Survivin axis was markedly up-regulated in established TMZ-insensitive glioma cell lines and HGG patients. Expression levels of FOXM1 and Survivin were positively correlated with each other and both related to poor prognosis in glioma patients. CONCLUSIONS: Bortezomib was found to inhibit glioma growth and improved TMZ chemotherapy efficacy, probably via down-regulating the FOXM1-Survivin axis. Bortezomib might be a promising agent for treating malignant glioma, alone or in combination with TMZ.

Long noncoding RNA UBE2R2-AS1 promotes glioma cell apoptosis via targeting the miR-877-3p/TLR4 axis.

Introduction: Brain glioma is the most common type of primary malignancy in the central nervous system (CNS), with high recurrence and mortality rate, especially glioblastoma (GBM). Recent evidence suggests a role for many long noncoding RNAs (lncRNAs) in the pathogenesis, proliferation, apoptosis, metastasis, and chemotherapeutic resistance of cancer cells. Although the functions of some lncRNAs in the occurrence and development of gliomas have been confirmed, detailed mechanisms of action are lacking. Furthermore, the biological roles of many other lncRNAs in glioma have not been reported at all. Methods: In this study, we identified a novel lncRNA, UBE2R2-AS1, which was dramatically downregulated in glioma compared with normal tissue, by performing microarray detection of six pairs of glioma samples and adjacent normal tissues. In vitro experiments demonstrated that UBE2R2-AS1 regulated glioma cell proliferation, apoptosis, and migration. Results: UBE2R2-AS1 acted as a competing endogenous RNA (ceRNA) to target Toll-like receptor 4 (TLR4) mRNA by binding to miR-877-3p. Furthermore, lncRNA UBE2R2-AS1 suppressed glioblastoma cell growth, migration, and invasion, as well as promoting cell apoptosis by targeting miR-877-3p/TLR4 directly. Conclusion: This information regarding UBE2R2-AS1 and its glioma-related molecular mechanisms will aid the future identification of new lncRNA-directed diagnostics and drug-targeting therapies.

Methylation-mediated miR-155-FAM133A axis contributes to the attenuated invasion and migration of IDH mutant gliomas.

Gliomas with isocitrate dehydrogenases gene mutations (IDHMT) were found to be less aggressive than their wildtype (IDHWT) counterparts. However, the mechanism remains unclear. The current study aims to investigate the role of silenced oncogenic microRNAs in IDHMT gliomas, which were largely ignored and may contribute to the less aggressive behavior of IDHMT gliomas. Microarrays, bioinformatics analysis of the data from TCGA and qPCR analysis of samples from our experimental cohort (LGG: IDHWT = 10, IDHMT = 31; GBM: IDHWT = 34, IDHMT = 9) were performed. The results show that miR-155 was consistently down-regulated in IDHMT gliomas. Establishment of IDH1R132H overexpressing glioma cell line and bisulfite sequencing PCR suggested that miR-155 down-regulation was associated with IDH1R132H mutation induced promoter CpG islands methylation. The cancer testis antigen FAM133A is a direct downstream target of miR-155 and is a negative regulator of glioma invasion and migration possibly by regulating matrix metallopeptidase 14 (MMP14). Together, we found that methylation-regulated miR-155-FAM133A axis may contribute to the attenuated invasion and migration of IDHMT gliomas by targeting MMP14.

Blood-Brain Barrier Disruption, Sodium Fluorescein, And Fluorescence-Guided Surgery Of Gliomas.

PURPOSE: Sodium fluorescein (SF) is an ideal dye for intraoperative guided-resection of high-grade gliomas (HGGs). However, it is not well understood whether the SF-guided technique is suitable for different grades of gliomas, and the correlation between fluorescence and pathology is also not yet clear. MATERIALS AND METHODS: In this study, we investigated 28 patients, including 23 patients with HGG and 5 patients with low-grade glioma (LGG). All patients were treated using the SF-guided technique on a Pentero 900 microscope (Carl Zeiss, Oberkochen, Germany). Claudin-5 immunohistochemical (IHC) staining for the tumours and peritumour tissues was analyzed. RESULTS: Intraoperative yellow fluorescence was noted in all the HGGs but not in the LGGs. Claudin-5 expression in the blood brain barrier endothelial cells was downregulated and disconnected in the HGGs (p < 0.05), but had no difference or slightly decreased in the LGGs (p > 0.05). CONCLUSIONS: The SF-guided technique is suitable for HGG surgery but not for LGG surgery. Downregulation of claudin-5 expression may contribute to the presence of yellow fluorescence in the glioma in SF-guided surgery.

MiR-206 is down-regulated and suppresses cell proliferation by targeting FOXP1 in brain gliomas.

Aberrant expression of miR-206 has been repeatedly found and demonstrated to play crucial roles in cancers. However, the role of miR-206 in brain glioma remains unclear. To address this issue, we detected miR-206 expression of 60 gliomas and 18 normal peritumor tissues, and found that miR-206 is significantly down-regulated in gliomas. Further in silico analysis of 198 glioma samples from the Chinese Glioma Genome Atlas (CGGA) indicated that miR-206 is significantly down-regulated in high grade gliomas and that miR-206 predicts favorable patients' prognosis. Notably, we found that miR-206 expression is negatively correlated with Ki-67 staining, indicating a proliferative inhibition of miR-206 in gliomas. To explore the crucial role of miR-206 in gliomas, we constructed miR-206 stably overexpressed LN229 glioma cell lines and found that the proliferation is significantly inhibited. Through flow cytometry (FCM) analyses, we found that the apoptotic rate is increased and the cell cycle is arrested in LN229 cells after overexpression of miR-206. Bioinformatic analysis, qPCR, western blot and luciferase assay indicated that the Forkhead Box Protein 1 (FOXP1) is a direct target of miR-206 in gliomas. Overexpression of FOXP1 could partially rescue the proliferative inhibition in the miR-206 stably overexpressed LN229 cells. In summary, our results suggest that miR-206 might function as a tumor suppressor of gliomas by inhibition of proliferation and could serve as a promising candidate for therapeutic applications in glioma by targeting FOXP1.

Pyrrolidine dithiocarbamate sensitizes U251 brain glioma cells to temozolomide via downregulation of MGMT and BCL-XL.

The current study investigated the effect of pyrrolidine dithiocarbamate (PDTC) on the proliferation, apoptosis, cell cycle and sensitivity to temozolomide (TMZ) of the U251 glioma cell line. Proliferation, apoptosis and cell cycle analysis of U251 cells following treatment with PDTC and TMZ was determined by an MTT assay and flow cytometry, respectively. The mRNA and protein expression levels of O-6-methylguanine-DNA methyltransferase (MGMT), B-cell lymphoma extra-large (BCL-XL) and survivin were further determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting analysis. The results revealed that treatment with TMZ, PDTC and TMZ + PDTC significantly inhibited cell proliferation, induced apoptosis and contributed to cell cycle arrest in U251 cells. A combination of PDTC and TMZ induced the highest rates of proliferation inhibition and apoptosis. PDTC treatment markedly reduced the expression levels of MGMT, BCL-XL and survivin. The expression levels of MGMT and BCL-XL, were significantly upregulated by TMZ but not by combination treatment of TMZ and PDTC. The results of the present study suggest that treatment with PDTC inhibits cell proliferation, induces apoptosis and cell cycle arrest, and enhances sensitivity to TMZ in U251 cells, which is partly induced by downregulation of MGMT and BCL-XL.

Downregulation of HIF-1a sensitizes U251 glioma cells to the temozolomide (TMZ) treatment.

PURPOSE: The aim of this study was to investigate the effect of downregulation of HIF-1α gene on human U251 glioma cells and examine the consequent changes of TMZ induced effects and explore the molecular mechanisms. METHODS: U251 cell line stably expressing HIF-1α shRNA was acquired via lentiviral vector transfection. The mRNA and protein expression alterations of genes involved in our study were determined respectively by qRT-PCR and Western blot. Cell proliferation was measured by MTT assay and colony formation assay, cell invasion/migration capacity was determined by transwell invasion assay/wound healing assay, and cell apoptosis was detected by flow cytometry. RESULTS: We successfully established a U251 cell line with highly efficient HIF-1α knockdown. HIF-1a downregulation sensitized U251 cells to TMZ treatment and enhanced the proliferation-inhibiting, invasion/migration-suppressing, apoptosis-inducing and differentiation-promoting effects exerted by TMZ. The related molecular mechanisms demonstrated that expression of O(6)-methylguanine DNA methyltransferase gene (MGMT) and genes of Notch1 pathway were significantly upregulated by TMZ treatment. However, this upregulation was abrogated by HIF-1α knockdown. We further confirmed important regulatory roles of HIF-1α in the expression of MGMT and activation of Notch1 pathways. CONCLUSION: HIF-1α downregulation sensitizes U251 glioma cells to the temozolomide treatment via inhibiting MGMT expression and Notch1 pathway activation.

Microarray analysis of the aberrant microRNA expression pattern in gliomas of different grades.

Previous studies have focused on miRNA expression in brain gliomas. However, both the expression pattern of miRNAs in gliomas of different grades and various miRNAs involved in malignant progression of gliomas are poorly understood. In the present study, we used miRNA microarray-based screening to investigate the miRNA expression profile in gliomas, which was further verified by qRT-PCR in selected miRNAs. In total, we found 13 differentially expressed miRNAs between gliomas and their matched surrounding tissues. Among them, 12 miRNAs were upregulated and only one (miR-4489) was downregulated compared with the control. Furthermore, the lower expression level of miR-4489 was confirmed by qRT-PCR in 26 glioma samples. Our microarray result revealed 8, 9 and 15 aberrantly expressed miRNAs in gliomas of World Health Organization (WHO) grade II-IV, respectively. Gene Ontology (GO) and Pathway analysis indicated that target genes of the 13 miRNAs were significantly enriched in central nervous system- and tumor-related biological processes and signaling pathways. The dysregulated miRNAs identified in the present study contribute to the tumorigenesis and malignant progression of gliomas and may serve as useful markers for advanced glioma pathological grading and prognosis.