title: Glioblastoma cells induce differential glutamatergic gene expressions in human tumor-associated microglia/macrophages and monocyte-derived macrophages.
abstract: Glioblastoma cells produce and release high amounts of glutamate into the extracellular milieu and subsequently can trigger seizure in patients. Tumor-associated microglia/macrophages (TAMs), consisting of both parenchymal microglia and monocytes-derived macrophages (MDMs) recruited from the blood, are known to populate up to 1/3 of the glioblastoma tumor environment and exhibit an alternative, tumor-promoting and supporting phenotype. However, it is unknown how TAMs respond to the excess extracellular glutamate in the glioblastoma microenvironment. We investigated the expressions of genes related to glutamate transport and metabolism in human TAMs freshly isolated from glioblastoma resections. Quantitative real-time PCR analysis showed (i) significant increases in the expressions of GRIA2 (GluA2 or AMPA receptor 2), SLC1A2 (EAAT2), SLC1A3 (EAAT1), (ii) a near-significant decrease in the expression of SLC7A11 (cystine-glutamate antiporter xCT) and (iii) a remarkable increase in GLUL expression (glutamine synthetase) in these cells compared to adult primary human microglia. TAMs co-cultured with glioblastoma cells also exhibited a similar glutamatergic profile as freshly isolated TAMs except for a slight increase in SLC7A11 expression. We next analyzed these genes expressions in cultured human MDMs derived from peripheral blood monocytes for comparison. In contrast, MDMs co-cultured with glioblastoma cells compared to MDMs co-cultured with normal astrocytes exhibited decreased expressions in the tested genes except for GLUL. This is the first study to demonstrate transcriptional changes in glutamatergic signaling of TAMs in a glioblastoma microenvironment, and the findings here suggest that TAMs and MDMs might potentially elicit different cellular responses in the presence of excess extracellular glutamate.
authors.affiliation: a Johannes Gutenberg University of Mainz; Mainz, Germany.
authors.forename: Judy
authors.initials: J
authors.lastname: Choi
authors.forename: Beate
authors.initials: B
authors.lastname: Stradmann-Bellinghausen
authors.forename: Eduard
authors.initials: E
authors.lastname: Yakubov
authors.forename: Nicolai E
authors.initials: NE
authors.lastname: Savaskan
authors.forename: Anne
authors.initials: A
authors.lastname: Régnier-Vigouroux
mesh_terms: D015703:Antigens, CD / Q000235:genetics; D015214:Antigens, Differentiation, Myelomonocytic / Q000235:genetics; D001253:Astrocytes / Q000166:cytology / Q000502:physiology; D001932:Brain Neoplasms / Q000235:genetics / Q000473:pathology*; D039481:CD11b Antigen / Q000235:genetics; D002135:Calcium-Binding Proteins; D018920:Coculture Techniques; D004268:DNA-Binding Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D005909:Glioblastoma / Q000235:genetics / Q000473:pathology*; D018698:Glutamic Acid / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D017493:Leukocyte Common Antigens / Q000235:genetics; D008264:Macrophages / Q000473:pathology / Q000502:physiology*; D008840:Microfilament Proteins; D017628:Microglia / Q000166:cytology* / Q000502:physiology; D018091:Receptors, AMPA / Q000235:genetics; D014407:Tumor Cells, Cultured; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D039481:CD11b Antigen; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D018698:Glutamic Acid; D017493:Leukocyte Common Antigens; D008840:Microfilament Proteins; D018091:Receptors, AMPA; C112986:AIF1 protein, human; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C509295:ITGAM protein, human; C516769:PTPRC protein, human; C104722:glutamate receptor ionotropic, AMPA 2
keywords: GS, glutamine synthetase; HBSS, Hanks' Balance Salts Solution; IL-10, interleukin-10; MACS, magnetic-activated cell sorting; MDMs, monocytes-derived macrophages; MRC1, mannose receptor; NHA, normal human astrocytes; TAMs, Tumor-associated microglia/macrophages; VEGF, vascular endothelial growth factor; glioblastoma; glutamate; monocyte-derived macrophages; qRT-PCR, quantitative real-time PCR; tumor-associated microglia/macrophages