Fig. 1: Inhibition of overexpressed HDAC1/2/3 sensitizes glioma cells towards TMZ.

A Microarray expression data obtained from ArrayExpress of HDAC1 (NM_004964), HDAC2 (NM_001527), HDAC3 (NM_003883) and HDAC8 (NM_018486) from 23 epilepsy sufferers, 45 grade II oligodendroglioma and astrocytoma tumors, 12 grade III oligodendroglioma tumors and 81 grade IV glioblastoma tumors. Indicated significances result from a Mann–Whitney test. B Western blot analysis of HDAC1/2/3 protein levels in LN229, A172, U87MG, LN308 glioma cell lines and the glioma initiating cell lines #1095, #1095_IR compared to non-cancerous HUVECs and astrocytes. HSP90 served as a loading control. C Western blot analysis showing the influence of class I HDAC inhibition by MS-275 (1.5 µM for 72 h) on acetylated-H4 in LN229, A172, U87MG, and LN308 cells. ß-ACTIN served as a loading control. D Apoptosis and necrosis in the glioma cell lines LN229, A172, U87MG, and LN308 induced by the indicated drugs. Indicated significances result from a paired t-test. E Clonal survival of LN229 glioma cells exposed to TMZ in the absence and presence of MS-275 (1.5 µM). F Apoptosis and necrosis induced in non-cancerous cells (Astrocytes and HUVECs) exposed to the indicated drugs. Indicated significances result from a paired t-test. *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001, and ****P ≤ 0.0001. For D and F cells were exposed to MS-275 (1.5 µM), TMZ (50 µM) and TMZ/MS-275. Cell death response was determined by flow cytometric analysis of Annexin V-FITC/PI double-staining 120 h and 144 h after treatment for D and F, respectively.