GFAP-transfected SF-126 human astrocytoma cells were shown to overexpress the phosphorylated form of FAK only when these cells were placed on a fibronectin matrix.
We have previously transfected GFAP-negative human astrocytoma cells with the gene for GFAP and have demonstrated that GFAP transfection decreases astrocytoma proliferation and alters astrocytoma morphology.
This pattern of IF gene expression was different from that of the astrocytoma and neuroblastoma cell lines, which expressed IF genes usually associated with the mature cell types or with differentiating fetal neural precursor cells, i.e.GFAP and neurofilament-L.
When assessed in an in vitro invasion assay system, antisense GFAP-transfected astrocytoma cells more readily penetrated Matrigel-coated filters than did controls.
These results: (a) provide molecular data confirming the classification of the two cell lines as oligodendrogliomal and suggest that their molecular profiles are indicative of immature oligodendrocytes; (b) demonstrate the expression of cytokeratins in oligodendrogliomal cell lines and suggest that apparent GFAP expression in oligodendrogliomas detected by immunocytochemical methods may be due to cross-reactivity with cytokeratins, with which they share common polypeptide sequence; and (c) indicate that astrocytoma cell lines can exhibit a "mixed" phenotype, expressing genes associated with fully differentiated oligodendrocytes and neurons.
To investigate the function of GFAP, we have studied the human astrocytoma cell line, U251, which constitutively expresses GFAP and vimentin in the same 10-nm filaments.
Glial fibrillary acidic protein (GFAP) mRNA levels in the human astrocytoma line U-373MG were examined to explore further the effects of agents that regulate protein kinase C. U-373MG cells exhibit a biphasic change in steady-state GFAP mRNA in the presence of the phorbol ester phorbol-12-myristate-13-acetate (PMA).