Growth inhibitory effect of the HDAC inhibitor vorinostat and the PI3K inhibitor LY-294002 on T-ALL cell lines. (A) Negative correlation of the T-ALL gene expression signature with vorinostat and LY-294002. CMAP analysis was performed on a T-ALL gene expression signature with 6100 instances of compounds. Green and red represent positive and negative correlation, respectively. Each dataset is indicated by a black bar. (B) IC₅₀ values with the HDAC inhibitor vorinostat and the PI3K inhibitor LY-294002. Mouse leukemic DP cells (mouse T-ALL) and various types of human leukemia/cancer cell lines were treated for 3 days with vorinostat or LY-294002 (1 mouse T-ALL, 4 GSI-sensitive T-ALL, 4 GSI-resistant T-ALL, 3 AML, 4 B-NHL/MM/CLL, 4 NBL, and 4 other cancer cell lines). The number of viable cells was measured by the MTT assay, and IC₅₀ values were calculated for each cell. (C-D) Synergistic effects of LY-294002 and vorinostat in combination with GSI. Three GSI-sensitive and 3 GSI-resistant T-ALL cell lines were treated with or without LY-294002 (10μM; C) or vorinostat (0.3μM; D) in the presence or absence of GSI MRK-003 (1μM) for 6 days. The number of viable cells was measured by MTT assay.