ATL-specific transcriptome of epigenetic regulators. (A) Expression pattern of epigenetic factors shown by heat map (left) and mean expression levels (right graph) based on gene-expression profiles of acute-type ATL cells (n = 26) and normal CD4⁺ T cells (n = 21). (B) Summary of EZH2 mutation status at Y641, A677, and A687 in patient samples from ATL (n = 50) and cell lines. (C) ATL cell lines were transduced with lentivirus vectors carrying short hairpin RNA (shRNA) targeting EZH2 or SUZ12, followed by long-term culture in complete medium. Results as percentage of each Venus-positive population transduced with shRNA series are plotted (n = 3, mean ± SD). (D) Dose-dependent effect of an EZH2 inhibitor GSK126 on cell proliferation in TL-Om1 (ATL-derived) and WSU-DLCL2 (GCB-DLBCL–derived) cells. (E) Apoptosis induction by GSK126 treatment. TL-Om1 cells were treated with 5 μM of GSK126 for 6 days. The apoptotic cells were detected by Annexin V staining. (F) GSK126-dependent apoptosis induction in primary ATL cells. PBMCs from ATL patients (n = 8) were treated with 5 µM of GSK126 for 4 days. The CD4⁺/Annexin V⁺ cells were calculated by flow cytometry (P < .05). (G-H) Western blots showing H3K27me3 level in TL-Om1 cells (G) and primary ATL cells (H) treated with GSK126 at indicated concentrations for 6 days. Mean intensity of H3K27me3 blot from 3 ATL samples is shown.