Retention of an appropriate astrocytic response to retinoids by human brain tumors comprised of predominantly glial fibrillary acidic protein-positive cells.
It has been demonstrated that glial fibrillary acidic protein (GFAP)-positive astrocyte precursors will differentiate in response to application of retinoic acid (RA), whereas GFAP/oligodendrocyte type 2-astrocyte progenitors will be inhibited from differentiating and continue to be mitotically active in the presence of RA. The authors sought to determine if cells taken from glial tumors that were GFAP positive retained the ability to differentiate following application of RA in vitro, as their normal astrocytic counterparts do. Primary cultures of seven astrocytic tumors were observed to have significantly fewer cells following 1 month of continuous exposure to 100 microM RA. Comparisons with sister control cultures indicated that in control conditions the tumor cells had undergone proliferation, whereas the number of cells in the RA-exposed cultures remained closer to the number of cells initially plated. This response to RA was demonstrated to be specific to the astrocytic tumors by virtue of the fact that cultures of normal brain and an anaplastic ependymoma both showed a strong proliferative response to retinoids.
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Division of Neurosurgery and Brain Tumor Laboratories, Brigham & Women's Hospital, Boston, Massachusetts.
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