ZDHHC17-MAP2K4 Signaling Module Promotes Chemoradiotherapy Resistance in GBM Spheres. (A) mRNA expression analysis (Mao's dataset, GSE67089) of ZDHHC17 expression in mesenchymal (MES) GSCs compared to normal astrocytes, or proneural (PN) GSCs. (B) Genome-wide transcriptome microarray analysis (GSE67089) of MAPKKs showing MAP2K4 up-regulation in MES compared with PN GSCs. (C) RT-PCR for ZDHHC17 and MAP2K4 in post-radiation GSCs from U118MG (6 Gy) or temozolomide (TMZ)-treated (25 μM) versus naive GSCs. (D) Western blot for ZDHHC17, MAP2K4, and EZH2 in post-radiation GSCs from U118MG (6 Gy) or TMZ-treated GSCs (25 μM) versus naive GSCs. (E) Flow cytometric analysis for apoptosis in GSCs pre-transduced with control or ZDHHC17 dsRNA, then treated with or without genistein (2.5 μM), radiation (6 Gy), and TMZ (25 μM). (F) BALB/c mice were subcutaneously injected with GSCs from U118MG. After five days, the nude mice were treated with 20 Gy X-irradiation (4.5-4.6 Gy/min), TMZ (50 mg kg-1 two days-1, gastric infusion), or genistein (100 mg/kg daily, tail vein injection). Tumor weight was quantified. Data represent the means ± SD from five separate experiments (ns, not significant; **p < 0.01; ***p < 0.001, unpaired t-test). (G) Typical immunohistochemistry images for ZDHHC17 and MAP2K4 in primary untreated and post-radiation and -TMZ chemotherapy recurrent tumors from matched patients with GBM. Scale bars, 200 µm. (H) Percentage of ZDHHC17 or MAP2K4 positive-stained cells in primary untreated and recurrent tumors from matched patients with GBM (n = 5; *p < 0.05; **p < 0.01; ***p < 0.001).