Microarray analysis of aristolochic acid in normal human cells

Aim： Use microarray analysis to understand the molecular mechanism underlying the effect of aristolochic acid (AA), a major active component of plants from the Aristolochiaceae family, in normal human kidney (HK-2) cells. Methods： HK-2 cells were treated with AA for 24 hours and cell viability was measured by a 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay. Complementary DNA microarrays were used to investigate the gene expression pattern of HK-2 cells exposed to AA and the results of this study were in triplicate. Quantitative real-time RT-PCR assay was used to verify the microarray data for selected nuclear factor kappa B (NF-κB)-regulated genes. Furthermore, subcellular localization of NF-κB p65 was visualized by immunofluorescence confocal microscopy in HK-2 cells. NF-κB activity was examined by luciferase reporter assay in HK-2/NF-κB transgenic cells. Results： AA exhibited a dose-dependent cytotoxic effect in HK-2 cells and induced alterations in gene expression profiles related to DNA damage response, stress response, etc. In addition, 9 biological pathways associated with immunomodulatory functions were down-regulated in AA-treated HK-2 cells. Network analysis revealed that NF-κB played a central role in the network topology. Among NF-kB-regulated genes, 8 differentially expressed genes were verified by real-time RT-PCR. The inhibition of NF-κB activity by AA was further confirmed by immunofluorescence confocal microscopy and by NF-κB luciferase reporter assay. Conclusion： Our data revealed that AA could suppress NF-κB activity in normal human cells, perhaps partially accounting for the reported anti-inflammatory effects of some plants from the genus Aristolochia. HK-2 cells were grown in keratinocyte serum-free basal medium (Gibco) supplemented with 5 ng/ml of recombinant epidermal growth factor and 50 μg/ml of bovine pituitary extract without antibiotics in 5 % CO2 at 370C. HK-2 cells were seeded in 25-T flasks and incubated for 24 h before aristolochic acid treatment. Aristolochic acid (10 90 μM) were added to HK-2 cells for 24 h. The control cells received equal amounts of water only.