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

Department of Human Morphology and Biomedical Sciences Città Studi, Extracellular Matrix Laboratory-EML, School of Medicine, University of Milan, Milano, Italy.
Oncology Reports (Impact Factor: 2.3). 12/2009; 22(6):1349-56. DOI: 10.3892/or_00000574
Source: PubMed


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.

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Available from: Nicoletta Gagliano
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    • "Some aggressive tumors including glioblasomas were shown to release microvesicles (exosomes) containing mRNA, DNA, enzymes, oncogenic receptors, growth factors, and miRNA, which after their uptake by surrounding non-tumors cells induce oncogenic transformation of neighbors (Al-Nedawi et al., 2008; Antonyak et al., 2011; Graner et al., 2009; Skog et al., 2008). Co-cultivating of human neural stem cell-derived astrocytes and U87 MG astrocytoma cells resulted in the malignantlike phenotype acquired by astrocytes from tumor cells (Gagliano et al., 2009). Recently, Katakowski et al. (2010) observed the ability of culturing rat gliosarcoma and human glioma cell lines share miRNA between neighboring cells through gap junctions, and this miRNA has a functional effect in the recipient cell via inhibiting expression of a target mRNA. "
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