Glioma-astrocyte interaction modifies the astrocyte phenotype in a co-culture experimental model

• Published in: Oncology reports Vol. 22; no. 6; pp. 1349 - 1356
• Main Authors: GAGLIANO, Nicoletta, COSTA, Francesco, COSSETTI, Chiara, PETTINARI, Letizia, BASSI, Rosaria, CHIRIV A-INTERNATI, Maurizio, COBOS, Everardo, GIOIA, Magda, PLUCHINO, Stefano
• Format: Journal Article
• Language: English
• Published: Athens Spandidos 01.12.2009
• Subjects: Astrocytes - metabolism; Astrocytes - pathology; Biological and medical sciences; Brain Neoplasms - pathology; Cell Line, Tumor; Coculture Techniques - methods; Connexin 43 - metabolism; Glioma - pathology; Humans; Medical sciences; Microscopy, Fluorescence - methods; Neurology; Neurons - metabolism; Osteonectin - metabolism; Phenotype; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Stem Cells - cytology; Tissue Inhibitor of Metalloproteinase-2 - metabolism; Tumors; Tumors of the nervous system. Phacomatoses; Nervous system diseases; matrix metalloproteinase-2; Enzyme; Neuroglia; Glial fibrillary acidic protein; Glioblastoma; secreted protein acidic and rich in cysteine; Metalloendopeptidases; Malignant tumor; Astrocyte; Connexin 43; Gelatinase A; Malignant glioma; Peptidases; Mixed cell culture; Phenotype; Cancerology; Central nervous system disease; Osteonectin; Hydrolases; Models; astrocytes; Cancer
• ISSN: 1021-335X; 1791-2431
• DOI: 10.3892/or_00000574

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.