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

Abstract

Abstract. 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-ß1 (TGF-ß1), 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 nonphosphorylated 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 cocultivated with U87, showing lower expression in glioma cells. By contrast, SPARC protein expression was strongly induced in supernatants of co-cultured astrocytes. TGF-ß1 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.

Glioma cells escaped from cytotoxicity of temozolomide and vincristine by communicating with human astrocytes

“…Research has shown that the astrocyte phenotype can be transformed through GJC [27]. In the transwell co-culture experiments, GFAP and matrix metalloproteinase-2 (MMP-2) in astrocytes were upregulated, while tissue inhibitor of MMP-2 (TIMP-2) and secreted protein acidic and rich in cysteine (SPARC) were downregulated [44].…”

Glioblastoma cells inhibit astrocytic p53-expression favoring cancer malignancy

“…Gagliano et al 42 have also shown that the co-culture of astrocytes with GBM cells increases the expression of MMP-2 and a decrease in TIMP-2 (tissue inhibitor of metalloproteinase) in astrocytes. Our work shows that GBM cells are able to modulate p53 expression of astrocytes, confirming that GBM is able to modulate protein expression of surrounding astrocytes as a way to favor malignancy.…”

In vivo ectopic chondrogenesis of BMSCs directed by mature chondrocytes

“…A transwell co-culture system was used to confirm the chondroinductive role of soluble factors secreted by chondrocytes [22,23]. BMSC-scaffold constructs and chondrocyte-scaffold constructs were co-cultured in a transwell system separated by a semipermeable membrane (pore size: 0.4 mm) (Fig.…”