Valproic acid inhibits proliferation and changes expression of CD44 and CD56 of malignant glioma cells in vitro

Recently we were able to show that valproic acid (WA) induces growth-arrest and differentiation of human neuroblastoma cells. Hence we investigated in vitro the antitumoral effects of VPA on malignant gliomas by determining c ell proliferation and expression of CD56 and CD44 of human T98G, A172, 85HG 66, 86HG39 and rat C6 cell lines. VPA at concentrations ranging from 0.1 to I mM strongly inhibited proliferation of A172, 86HG39, 85HG66 and C6 cells in a dose-dependent manner,whereas T98G cell growth remained unchanged. Al l human glioma cells were highly positive for CD44, whereas CD56 was differ ently expressed. After 7 days of incubation with 1mM VPA CD56 expression wa s markedly increased in T98G, A172 and 85HG66 cells, whereas CD44 expressio n was decreased in all human cell lines. These data suggest that VPA has an titumoral effects on malignant glioma cells. Therefore we consider VPA as a potent therapeutic agent for treatment of these tumors.