| Genetic alterations in astrocytic tumors have frequently been examined to determine areas of possible intervention. Adult and pediatric tumor samples as well as cell lines established from adult tumors have provided the substrate for these analyses. Many adult cell lines have been characterized and used as model systems to study brain tumor progression. However, limited numbers of pediatric astrocytic cell lines have been established for these purposes. Three new cell lines have been established from pediatric glioblastoma multiforme (GBM) patients and two from pediatric anaplastic astrocytoma (AA) patients. The cell lines were first characterized for the most common genetic alterations observed in astrocytic tumors and then were assessed for the potential to differentiate in response to neurotrophins or retinoids. One cell line expressed glial fibrillary acidic protein transcript. The transcripts for EGFR, c-myc, N-myc, and basic fibroblast growth factor were examined for alterations or overexpression of these genes. All five cell lines expressed elevated levels of the EGFR transcript when compared to the normal brain controls. One of the GBM cell lines expressed the c-myc transcript at high levels as a result of an amplified c-myc gene. Mutations in the p53 gene were found in all five cell lines. Three of the cell lines had dominant negative p53 mutations in codons 273 or 248. One cell line carried a mutation in codon 72 and the other had a loss of function mutation. The primary tumors from which the cell lines were derived also contained the same mutations. The expression of genes required for a potential response to differentiating agents were assessed. All five cell lines expressed transcripts for trkB and retinoic acid receptor {dollar}alpha , beta ,{dollar} and {dollar}gamma ;{dollar} three expressed retinoic acid X receptor {dollar}alpha ,{dollar} and one expressed transcripts for gp75{dollar}sp{lcub}rm NGFR{rcub}{dollar} and trkC. However, none of the cell lines differentiated after exposure to neurotrophins, retinoic acids, or retinols. Treatment with retinaldehydes had a cytotoxic effect. These in vitro findings may help to identify specific genes and compounds of interest when evaluating new treatment strategies. |
