Exogenous over-expression of HDAC7 inhibits ATX expression in cancer cells in a HDAC3-dependent manner. A, HDAC3 and HDAC7 protein levels, as well as ATX mRNA levels, were detected by Western blot and RT-PCR analyses, respectively, in 13 cancer cell lines (1, MDA-MB-231; 2, MCF-7; 3, MDA-MB-468; 4, Hela; 5, A549; 6, A2780; 7, HEY; 8, OCC1; 9, PC3; 10, Du145; 11, MDA-MB-435; 12, colo320; 13, HT-29). B and C, HDAC7 (B) or HDAC3 (C) over-expression plasmid was transfected into indicated cancer cells with empty vector as the control. ATX mRNA expression was detected by real-time RT-PCR 48 hrs post transfection. D, The indicated cancer cells were first transfected with non-specific siRNA (siNC) or HDAC3 siRNA for 24 hrs, followed by transfection of the HDAC7 over-expression plasmid. ATX mRNA expression levels were detected by real-time RT-PCR 48 hrs post the second transfection. The p values derived from Student's t test are (*) p < 0.005, (**) p < 0.001.