INHIBITORY EFFECTS OF PHENYLBUTYRATE ON THE PROLIFERATION, MORPHOLOGY, MIGRATION AND INVASIVENESS OF MALIGNANT GLIOMA-CELLS

The purpose of this study was to characterize the effects of sodium 4- phenylbutyrate (phenylbutyrate) on the proliferation, morphology, migr ation and invasiveness of malignant glioma cells in vitro. Phenylbutyr ate is a novel differentiating and cytotoxic compound used clinically with low toxicity in the treatment of beta-thalassemia, sickle cell an emia and urea cycle disorders. Preliminary clinical trials testing phe nylbutyrate as an anticancer agent have included patients with maligna nt glioma. However, little information is available regarding the effe cts of phenylbutyrate on glioma cells, particularly with respect to th e expression of genes important in the pathogenesis of glial malignanc y. In experiments reported here, glioma cell lines and explant cells f rom a tumor patient were exposed to 2, 4 and 8 mM phenylbutyrate and c ompared to untreated control cells. The effect on cellular proliferati on was assessed using cell counts and DNA flow cytometry. Changes in m orphology were evaluated using vimentin staining. Scratch and Matrigel assays were performed to assess changes in cellular migration and inv asiveness. Finally, Northern blot analysis was used to study c-myc and urokinase expression. Phenylbutyrate was found to have dose-dependent inhibitory effects on glioma cell proliferation, morphology, migratio n, invasiveness and c-myc and urokinase expression. Mean growth-inhibi tory (IC50) phenylbutyrate concentrations ranged from 0.5 mM for T98G cells to 5.0 mM for explant cells. Phenylbutyrate treatment reduced % S phase cells, increased % G(0)/G(1) cells, and produced morphologic c hanges consistent with induction of differentiation. 24 hours of treat ment with 4 mM phenylbutyrate resulted in a 50% reduction in migration and invasiveness. Northern blots showed a decrease in urokinase and c -myc expression at noncytotoxic doses. We conclude that phenylbutyrate is a promising candidate compound for treating patients with malignan t glioma.