Glioma is the most common and lethal intrinsic primary tumor of the brain. Its controversial origins may contribute to its heterogeneity, creating challenges and difficulties in the development of therapies. Among the components constituting tumors, glioma stem cells are highly plastic subpopulations that are thought to be the site of tumor initiation. Neural stem cells/progenitor cells and oligodendrocyte progenitor cells are possible lineage groups populating the bulk of the tumor, in which gene mutations related to cell-cycle or metabolic enzymes dramatically affect this transformation. Novel approaches have revealed the tumor-promoting properties of distinct tumor cell states, glial, neural, and immune cell populations in the tumor microenvironment. Communication between tumor cells and other normal cells manipulate tumor progression and influence sensitivity to therapy. Here, we discuss the heterogeneity and relevant functions of tumor cell state, microglia, monocyte-derived macrophages, and neurons in glioma, highlighting their bilateral effects on tumors. Finally, we describe potential therapeutic approaches and targets beyond standard treatments.
Humans ; Glioma/metabolism* ; Neuroglia/metabolism* ; Carcinogenesis/pathology* ; Neural Stem Cells/metabolism* ; Microglia/metabolism* ; Brain Neoplasms/metabolism* ; Tumor Microenvironment

OBJECTIVETo review the leading roles of glioma stem cells (GSCs) and their sophisticated interactions with other cells in the tissue remodeling process of gliomagenesis.

DATA SOURCESPublished articles about assessing GSCs in tumor initiation, progression, and multiple interactions with other cells in the special microenvironment were selected using PubMed. The search terms were "glioma stem cells", "tumorigenesis", and "microenvironment".

STUDY SELECTIONArticles regarding the tissue remodeling of GSCs in gliomagenesis were selected.

RESULTSGSCs exhibit enhanced tumor-initiating ability, could reestablish tumor, and were resistant to radiotherapy and chemotherapy. Studying the role of GSCs in gliomagenesis helps to develop targeting therapy against GSCs, which seems to be a cure for gliomas. However, sophisticated interactions between GSCs and their local microenvironment during tumor remodeling, including integrating with partially differentiated tumor cells, GSCs niche, neural stem cells (NSCs), normal glia, tumor-infiltrating lymphocytes, may obscure the leading role of GSCs during gliomagenesis, and make single targeting therapy unsuccessful.

CONCLUSIONSUnderstanding the biological behaviour of GSCs and their regulatory mechanisms may directly impact current efforts for more directed therapeutics against the highly aggressive gliomas. For multiple possible sources to turning into GSCs, simply eradicating the existing GSCs is not enough to be a cure for gliomas, blocking the potential sources of GSCs and ameliorating the local tumor inducing/promoting microenvironment should be a reasonable strategy.

AC133 Antigen ; Antigens, CD ; Biomarkers, Tumor ; metabolism ; Glioma ; metabolism ; pathology ; Glycoproteins ; Humans ; Neoplastic Stem Cells ; metabolism ; pathology ; Peptides

Detailed characterizations of genomic alterations have not identified subtype-specific vulnerabilities in adult gliomas. Mapping gliomas into developmental programs may uncover new vulnerabilities that are not strictly related to genomic alterations. After identifying conserved gene modules co-expressed with EGFR or PDGFRA (EM or PM), we recently proposed an EM/PM classification scheme for adult gliomas in a histological subtype- and grade-independent manner. By using cohorts of bulk samples, paired primary and recurrent samples, multi-region samples from the same glioma, single-cell RNA-seq samples, and clinical samples, we here demonstrate the temporal and spatial stability of the EM and PM subtypes. The EM and PM subtypes, which progress in a subtype-specific mode, are robustly maintained in paired longitudinal samples. Elevated activities of cell proliferation, genomic instability and microenvironment, rather than subtype switching, mark recurrent gliomas. Within individual gliomas, the EM/PM subtype was preserved across regions and single cells. Malignant cells in the EM and PM gliomas were correlated to neural stem cell and oligodendrocyte progenitor cell compartment, respectively. Thus, while genetic makeup may change during progression and/or within different tumor areas, adult gliomas evolve within a neurodevelopmental framework of the EM and PM molecular subtypes. The dysregulated developmental pathways embedded in these molecular subtypes may contain subtype-specific vulnerabilities.
Humans ; Brain Neoplasms/pathology* ; Neoplasm Recurrence, Local/metabolism* ; Glioma/pathology* ; Neural Stem Cells/pathology* ; Oligodendrocyte Precursor Cells/pathology* ; Tumor Microenvironment

OBJECTIVETo investigate the anti-tumor effects of melittin against malignant human glioma cells in vitro.

METHODSTwo malignant human glioma cell lines (U87 and U251) were treated with melittin at various concentrations, and the cell growth inhibition and apoptosis were evaluated using MTT assay, flow cytometry and agarose gel electrophoresis.

RESULTSMelittin could obviously inhibit the proliferation of the two glioma cell lines (P<0.05). At the concentrations of 1, 10, 20, 40, 80, 160, 200 mg/L, melittin resulted in U87 cell apoptosis rates of 12.80%, 16.92%, 22.69%, 34.05%, 41.82%, 59.87%, and 80.25%, and in U251 cell apoptosis rate of 11.61%, 16.21%, 22.03%, 30.57%, 41.10%, 58.33%, and 79.12%, respectively, showing a dose-dependent effect in its action of inducing cell apoptosis.

CONCLUSIONMelittin inhibits the proliferation and induces apoptosis of malignant human glioma cell lines in vitro.

Apoptosis ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Glioma ; metabolism ; pathology ; Humans ; Melitten ; pharmacology

BACKGROUNDRecent studies have suggested that cancer stem cells are one of the major causes for tumor recurrence due to their resistance to radiotherapy and chemotherapy. Although the highly invasive nature of glioblastoma (GBM) cells is also implicated in the failure of current therapies, it is not clear how glioma stem cells (GSCs) are involved in invasiveness. Rac1 activity is necessary for inducing reorganization of actin cytoskeleton and cell movement. In this study, we aimed to investigate the distribution characteristics of CD133+ cells and Rac1+ cells in GBM as well as Rac1 activity in CD133+ GBM cells, and analyze the migration and invasion potential of these cells.

METHODSA series of 21 patients with GBM were admitted consecutively and received tumor resection in Tianjin Medical University General Hospital during the first half of the year 2011. Tissue specimens were collected both from the peripheral and the central parts for each tumor under magnetic resonance imaging (MRI) navigation guidance. Immunohistochemical staining was used to detect the CD133+ cells and Rac1+ cells distribution in GBM specimens. Double-labeling immunofluorescence was further used to analyze CD133 and Rac1 co-expression and the relationship between CD133+ cells distribution and Rac1 expression. Serum-free medium culture and magnetic sorting were used to isolate CD133+ cells from U87 cell line. Rac1 activation assay was conducted to assess the activation of Rac1 in CD133+ and CD133 - U87 cells. The migration and invasive ability of CD133+ and CD133 - U87 cells were determined by cell migration and invasion assays in vitro. Student's t-test and one-way analysis of variance (ANOVA) test were used to determine statistical significance in this study.

RESULTSIn the central parts of GBMs, CD133+ cells were found to cluster around necrosis and occasionally cluster around the vessels under the microscope by immunohistological staining. In the peripheral parts of the tumors, CD133+ cells were lined up along the basement membrane of the vessels and myelinated nerve fibers. Rac1 expression was high and diffused in the central parts of the GBMs, and the Rac1+ cells were distributed basically in accordance with CD133+ cells both in the central and peripheral parts of GBMs. In double-labeling immunofluorescence, Rac1 was expressed in (83.14 ± 4.23)% of CD133+ cells, and CD133 and Rac1 co-expressed cells were located around the vessels in GBMs. Significantly higher amounts of Rac1-GTP were expressed in the CD133+ cells (0.378 ± 0.007), compared to CD133- cells (0.195 ± 0.004) (t = 27.81; P < 0.05). CD133+ cells had stronger ability to migrate (74.34 ± 2.40 vs. 38.72 ± 2.60, t = 42.71, P < 0.005) and invade (52.00 ± 2.28 vs. 31.26 ± 1.82, t = 30.76, P < 0.005), compared to their counterpart CD133- cells in transwell cell migration/invasion assay.

CONCLUSIONSThese data suggest that CD133+ GBM cells highly express Rac1 and have greater potential to migrate and invade through activated Rac1-GTP. The accordance of distribution between Rac1+ cells and CD133+ cells in GBMs implies that Rac1 might be an inhibited target to prevent invasion and migration and to avoid malignant glioma recurrence.

AC133 Antigen ; Antigens, CD ; metabolism ; Cell Line, Tumor ; Glioblastoma ; metabolism ; pathology ; Glioma ; metabolism ; pathology ; Glycoproteins ; metabolism ; Humans ; Immunohistochemistry ; In Vitro Techniques ; Peptides ; metabolism ; rac1 GTP-Binding Protein ; metabolism

BACKGROUNDP53 is one of the most studied tumor suppressors in the cancer research, and over 50% of human tumors carry P53 mutations. MDM-2 is amplified and/or overexpressed in a variety of human tumors of diverse tissue origin. The aim of this study was to examine the expression of P53 protein and MDM-2 protein in gliomas, and to investigate the relationship between the expression of the two proteins and the histopathological grades of glioma. The relationship between MDM-2 protein expression and P53 protein expression was also analyzed.

METHODSThe expression of P53 protein and MDM-2 protein was immunohistochemically detected using monoclonal antibodies in 242 paraffin embedded tissues, including 30 normal brain tissues from patients with craniocerebral injury and 212 tissues from patients with primary glioma (grade I - II group: 5 cases of grade I, 119 cases of grade II; and grade III--IV group: 53 cases of grade III, and 35 cases of grade IV).

RESULTSThe P53 positive rate was significantly higher in the glioma groups than in the control group (P < 0.0001). The P53 positive rate was significantly higher in glioma tissues of grade III - IV than in glioma tissues of grade I - II group (P = 0.001). The MDM-2 positive rate was significantly higher in glioma groups than in the control group (P < 0.0001). There was no significant difference in the MDM-2 positive rate between the two glioma groups (P = 0.936). The expression of P53 protein was not related to expression of MDM-2 protein (P = 0.069)

CONCLUSIONSOverexpression of P53 protein might be related to the occurrence and progression of glioma. Overexpression of MDM-2 protein may play an important role in glioma tumorigenesis, but may not be involved in glioma progression. The overexpression of MDM-2 protein was an early event in malignant transformation of glioma. MDM-2 may be a key player in glioma in its own right.

Glioma ; metabolism ; pathology ; Humans ; Immunohistochemistry ; In Vitro Techniques ; Proto-Oncogene Proteins c-mdm2 ; metabolism ; Tumor Suppressor Protein p53 ; metabolism

Brain Neoplasms ; diagnosis ; metabolism ; pathology ; Child ; Diagnosis, Differential ; Female ; Glioma ; pathology ; Humans ; Immunohistochemistry ; Magnetic Resonance Imaging ; Meningioma ; diagnosis ; metabolism ; pathology ; Mucin-1 ; metabolism ; Occipital Lobe ; Vimentin ; metabolism

Cell Proliferation ; Colony-Forming Units Assay ; Glioma ; pathology ; Hematopoietic Stem Cells ; pathology ; Humans ; Stem Cells ; cytology ; metabolism

Antigens, CD34 ; metabolism ; Astrocytoma ; metabolism ; pathology ; Carcinoma ; metabolism ; pathology ; Central Nervous System Neoplasms ; metabolism ; pathology ; Ependymoma ; metabolism ; pathology ; Fibroma ; metabolism ; pathology ; Ganglioglioma ; metabolism ; pathology ; Glial Fibrillary Acidic Protein ; metabolism ; Glioma ; metabolism ; pathology ; Gliosarcoma ; metabolism ; pathology ; Humans ; Immunohistochemistry ; Neoplasms, Neuroepithelial ; metabolism ; pathology ; Solitary Fibrous Tumors ; metabolism ; pathology

Animals ; Brain Neoplasms ; etiology ; metabolism ; pathology ; Glioma ; etiology ; metabolism ; pathology ; Humans ; Neoplastic Stem Cells ; pathology ; physiology ; Signal Transduction ; Stem Cell Research