Identification of genes responsive to paeoniflorin, a heat shock protein-inducing compound, in human leukemia U937 cells

PURPOSE AND BACKGROUND: Paeoniflorin (PF) isolated from peony root (Paeoniae radix) has been used as a herbal medicine in East Asia for its anti-allergic, anti-inflammatory, and immunoregulatory effects. PF is known to cause apoptosis and to be a chemical heat shock protein (HSP) inducer. With this information, the effects on the gene expression in human leukemia U937 cells treated with PF were investigated. METHODS: U937 cells, a human myelomonocytic cell line, were treated with PF at different concentrations (0-640 microg/ml). Expression level of Hsp70 was monitored by Western blotting. Gene expression was evaluated using high-density oligonucleotide microarrays and computational gene expression analysis tools and the results were verified by real-time quantitative PCR. RESULTS: Although cell viability was not affected after PF treatment at a high concentration of 640 microg/ml, PF treatment (80-640 microg/ml) significantly elevated Hsp70 expression in a concentration-dependent manner. When the cells were treated with PF (160 microg/ml; 30 min), 35 up-regulated and 29 down-regulated genes were identified. Among the differentially expressed genes, a significant genetic network containing CDC2, FOSL1 and EGR1 was associated with biological functions such as cell death, gene expression or cellular growth and proliferation. CONCLUSION: The present results indicate that PF affects the expression of many genes including Hsp70 and will provide a better understanding on the molecular mechanism of action of this compound in inducing HSPs in cells.