Despite several reports on the effects of HDAC KD in human and other species, a direct comparison of global gene expression changes between individual class I HDAC KD and HDACi treatment has not previously been per formed on human cancer cell lines. selleck bio In this report, we examined viability parameters and transcriptional profiles of human HDAC1, 2 and 3 KD, and directly compared expression profiles with treatment of near IC50 doses of two structurally distinct HDACi. the pan inhibitory hydroxamate belinostat and the class I selective short chain fatty acid valproic acid. Further, we compared HeLa class I HDAC KD microarray data with that obtained in a recent similar study on U2OS cells. Results Depletion of HDAC1, 2 and 3 affect viability Efficient and specific down regulation of HDAC1, 2 and 3 was obtained in HeLa cells at both protein and mRNA levels, by using the siRNA technol ogy.

Viability, as measured by metabolically active cells present in culture, was consistently reduced by 20, 23 and 16% following HDAC1, 2 and 3 KD, respectively. A similar effect was seen in HCT116 and MCF 7 cells. In HDAC1 2 double KD cells, prolifer ation was reduced by 35% and 25% when compared with single HDAC1 KD and HDAC2 KD cells, respectively. Apoptotic effector caspase 3 7 activity was significantly increased for HDAC1, 2 and combina tion KD, but not for HDAC3 KD alone. Further, a dose response of 1. 4, 1. 8 and 2. 3 fold increased apoptosis at 0. 1, 1. 0 and 10. 0 M at 24 hours is evident for belinostat treatment. No indication of cell cycle deregulation was observed for class I HDAC KD in HeLa at 48 hours post transfection.

However, an increase in the subdiploid pop ulation corresponding to fragmented cells was observed Dacomitinib for especially HDAC2 and to some extent in HDAC3 KD cells, though not for HDAC1 KD cells. In comparison, belinostat treatment showed marked cell cycle alterations and cell debris. HDAC1 knockdown reduces sensitivity to the HDACi belinostat Next, we examined how HeLa cells respond to HDACi treatment following individual class I HDAC enzyme down regulation. Interestingly, HDAC1 KD signif icantly increased IC50 values almost 2 fold towards the hydroxamate belinostat, which was not seen in response to either HDAC2 or 3 depletion. When examin ing VPA, no significance was observed for either HDAC KD condition. Gene expression profiles of belinostat and VPA treatment Global gene expression analysis has previously been per formed following HDACi treatment regimens primarily in human cell lines, but only once recently for indi vidual human class I HDAC KD. However, a direct comparison of gene expression profiles for each has not been reported.