Production of glial fibrillary acidic protein (GFAP) by neoplastic cells: adaptation to the microenvironment.

In 80 specimens of human glioma the production of glial fibrillary acidic protein (GFAP) by tumour cells invading meninges or connective tissue was studied immuno-cytochemically by the PAP technique. In 38 of 55 cases of astrocytoma, glioblastoma, gliosarcoma, and oligoastrocytoma, GFAP immunoreactivity was greater in the invading cells as compared with the main part of the neoplasm. Fifty-eight percent of the astroglial tumours invading the leptomeninges, all astroglial tumours invading connective tissue and all gliosarcomas showed enhanced GFAP immuno-reactivity of tumour cells getting in contact with collagenous tissue, whereas meningeal infiltrates of 25 non-astroglial tumours (oligodendroglioma, ependymoma, medulloblastoma) remained GFAP-negative like the main part of the respective tumours. In the majority of astroglial tumours an increase of GFAP immunoreactivity was found also in perivascular cells of the main part of the tumour. It is concluded that glioma cells are capable of adapting their cytoskeleton to their micro-environment. Contact with dense collagenous tissue appears as an important factor able to induce an increased production of GFAP by adjacent glial cells.