Profile of gene expression in K562 cells exposed to 2 mM sodium valproate for 12 hours using Agilent SurePrint G3 Human GE 8x60K Microarray.

To explore the mechanism underlying anti-leukaemia effect of sodium valproate, the growth and survival of the K562 cell line were investigated using the Annexin V/PI dual staining method. Global profiles of gene expression in K562 cells exposed to sodium valproate were assessed using gene expression microarray and validated by qRT-PCR. Gene ontology analysis was performed to establish the function of differentially expressed genes. The differentially expressed genes identified by using gene expression array were further used to query the CMAP database to retrieve a ranked list of compounds that act on the same intracellular targets as sodium valproate. A significant increase in cell apoptosis was observed in valproate exposed K562 cells using flow cytometry. A total of 706 transcripts were identified as being significantly differentially expressed. Eight differentially expressed genes that might be involved in apoptosis were verified by qRT-PCR. The significant enrichment analysis of gene ontology terms for the differentially expressed genes revealed that these genes are involved in many important biological processes such as apoptosis. The connectivity map analysis showed gene expression profile in K562 cells exposed to sodium valproate observed in this study was most similar to that of HDACi and PI3K inhibitor in the connectivity map database, suggesting that sodium valproate might exert anti-leukaemic action by inhibiting HDAC as well as inhibiting PI3K pathway. In conclusion, the data obtained in this study might provide the ground for further studies to elucidate the molecular and therapeutic potential of VPA in leukaemia treatment. Gene expression in K562 cell line were measured after exposure to 2 mM valproate for 12 hours or left untreated as a control using Agilent SurePrint G3 Human GE 8x60K Microarray.