Glioma-astrocyte interaction modifies the astrocyte phenotype in a co-culture experimental model.
As the majority of gliomas arise through malignant transformation of astrocytes, we aimed at investigating the interaction between malignant glioma cells and astrocytes in a co-culture experimental model. For this purpose we analyzed the expression of genes and proteins involved in tumor promotion and invasion, such as glial fibrillary acidic protein (GFAP), matrix metalloproteinase-2 (MMP-2), tissue inhibitor of MMP-2 (TIMP-2), transforming growth factor-beta1 (TGF-beta1), secreted protein acidic and rich in cysteine (SPARC), and connexin 43 (CX43). Co-cultures of human neural stem cell-derived astrocytes and U87 MG astrocytoma cells were performed in a transwell system. Gene expression was evaluated by real-time RT-PCR, and protein analysis was performed by Western blotting, SDS-zymography, and immunofluorescence. GFAP tended to be up-regulated in astrocytes co-cultivated with U87, suggesting a reactive response induced by glioma cells. CX43 mRNA tended to be down- regulated in co-cultured astrocytes, as well as the non-phosphorylated isoform at the protein level. MMP-2 mRNA tended to be up-regulated, and MMP-2 protein levels were significantly increased in astrocytes co-cultivated with U87. TIMP-2 and SPARC mRNA decreased in astrocytes co-cultivated with U87, showing lower expression in glioma cells. By contrast, SPARC protein expression was strongly induced in supernatants of co-cultured astrocytes. TGF-beta1 was not modified. Our results suggest that U87 cells elicit phenotype modifications in the neighbouring resident astrocytes very likely mediated by soluble factors. Glioma/astrocyte interaction could possibly trigger an astrocyte phenotype modification consistent with a malignant transformation, and favouring a more permissive environment for glioma cells invasion.
Gagliano
Nicoletta
N
Department of Human Morphology and Biomedical Sciences Città Studi, Extracellular Matrix Laboratory-EML, School of Medicine, University of Milan, Milano, Italy. nicoletta.gagliano@unimi.it
Costa
Francesco
F
Cossetti
Chiara
C
Pettinari
Letizia
L
Bassi
Rosaria
R
Chiriva-Internati
Maurizio
M
Cobos
Everardo
E
Gioia
Magda
M
Pluchino
Stefano
S
D001253:Astrocytes / Q000378:metabolism / Q000473:pathology*; D001932:Brain Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D018920:Coculture Techniques / Q000379:methods*; D018031:Connexin 43 / Q000378:metabolism; D005910:Glioma / Q000473:pathology*; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods; D009474:Neurons / Q000378:metabolism*; D015676:Osteonectin / Q000378:metabolism; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism
D018031:Connexin 43; D015676:Osteonectin; D012333:RNA, Messenger; D019716:Tissue Inhibitor of Metalloproteinase-2