Fig. 1

GBM stem cell (GSC) viability was reduced by forced KLF9 expression and HDAC inhibitor. a Dox-induced KLF9 expression in GBM1A neurosphere cells in a dose-dependent manner. b MTS assays of cell viability in GBM1A cells treated with Dox (0.1 μg/ml), LBH589 (25–100 nmol/L) alone, and combined treatment for 48 h. c Similar enhanced cell death in GBM1B cells was observed when treated with Dox (0.1 μg/ml) and LBH589 at 25–100 nmol/L. d Trypan blue staining showing that the combined treatment of Dox and LBH598 significantly induced cell death in GSCs. Neurosphere cells were dissociated to single cell suspension by vigorously pipetting and stained with trypan blue for 10 min. Number of trypan blue positive cells (white bar) and live cells (black bar) were counted and plotted. e Phase contrast photographs of GBM1A neurosphere cells treated with Dox, LBH589 alone, and combined treatment for 48 h. Upon combined Dox + LBH589 treatment, neurospheres displayed massive cell death. Bar = 50 μm. f GBM1B cells were grown on laminin-coated surfaces as adherent cultures and treated with Dox + LBH589. After 48 h, significant cell death was observed under the combined treatment. Bar = 50 μm. g A close look at the morphology of dead cells in the Dox + LBH treated cultures revealed the process of both apoptosis and necrosis. The non-viable cells exhibited apoptotic cell bodies (left panel) and membrane rapture, ghost-like cell debris (right panel), indicating a necrotic phenotype. Bar = 10 μm. *: P < 0.05