Article

Aristolochic acid suppresses DNA repair and triggers oxidative DNA damage in human kidney proximal tubular cells

School of Chinese Medicine, China Medical University, Taichung, Taiwan.
Oncology Reports (Impact Factor: 2.3). 07/2010; 24(1):141-53. DOI: 10.3892/or_00000839
Source: PubMed

ABSTRACT

Aristolochic acid (AA), derived from plants of the Aristolochia genus, has been proven to be associated with aristolochic acid nephropathy (AAN) and urothelial cancer in AAN patients. In this study, we used toxicogenomic analysis to clarify the molecular mechanism of AA-induced cytotoxicity in normal human kidney proximal tubular (HK-2) cells, the target cells of AA. AA induced cytotoxic effects in a dose-dependent (10, 30, 90 microM for 24 h) and time-dependent manner (30 microM for 1, 3, 6, 12 and 24 h). The cells from those experiments were then used for microarray experiments in triplicate. Among the differentially expressed genes analyzed by Limma and Ingenuity Pathway Analysis software, we found that genes in DNA repair processes were the most significantly regulated by all AA treatments. Furthermore, response to DNA damage stimulus, apoptosis, and regulation of cell cycle, were also significantly regulated by AA treatment. Among the differentially expressed genes found in the dose-response and time-course studies that were involved in these biological processes, two up-regulated (GADD45B, NAIP), and six down-regulated genes (TP53, PARP1, OGG1, ERCC1, ERCC2, and MGMT) were con-firmed by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). AA exposure also caused a down-regulation of the gene expression of anti-oxidant enzymes, such as superoxide dismutase, glutathione reductase, and glutathione peroxidase. Moreover, AA treatment led to increased frequency of DNA strand breaks, 8-hydroxydeoxyguanosine-positive nuclei, and micronuclei in a dose-dependent manner in HK-2 cells, possibly as a result of the inhibition of DNA repair. These data suggest that oxidative stress plays a role in the cytotoxicity of AA. In addition, our results provide insight into the involvement of down-regulation of DNA repair gene expression as a possible mechanism for AA-induced genotoxicity.

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    • "The mechanisms by which AA induced nephrotoxicity are not yet fully revealed. Recently, it was reported that AA-induced nephrotoxicity was related to oxidative stress produced by PTECs (Chen et al., 2010). AAI seems to directly cause renal damage by activating mitochondrial permeability transition and endoplasmic reticulum stress (Hsin et al., 2006; Qi et al., 2007). "
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    ABSTRACT: Bardoxolone methyl (BARD) is an antioxidant modulator that acts through induction of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. This study aimed to investigate the role of BARD in protecting kidneys from aristolochic acid (AA)-induced acute kidney injury (AKI). Male C57BL/6 mice received intraperitoneal (i.p.) injections of aristolochic acid I (AAI) (5 mg/kg/day) for 5 days to produce acute AA nephropathy (AAN) model. BARD (10 mg/kg/day, i.p.) was applied for 7 consecutive days, starting 2 days prior to AAI administration. The mice in the AA group showed AKI as evidenced by worsening kidney function evaluated by blood urea nitrogen (BUN) and serum creatinine (SCr) levels, and severe tubulointerstitial injury marked by massive tubule necrosis in kidney tissues. BARD significantly reduced BUN and SCr levels which were elevated by AAI. Additionally, AAI-induced histopathological renal damage was ameliorated by BARD. Furthermore, the expression of Nrf2 was reduced, and its repressor Kelch-like ECH-associated protein 1 (Keap1) was increased significantly, whereas heme oxygenase-1 (HO-1) was upregulated and NAD(P)H quinone oxidoreductase-1 (NQO1) was barely increased in the cytoplasm of tubules in kidneys after treatment with AAI. BARD significantly upregulated renal Nrf2, NQO1 and HO-1 expression and downregulated Keap1 expression compared with those in the AA group. Moreover, it was found that Nrf2 was expressed both in the cytoplasm and nuclear of glomeruli and tubules, whereas NQO1 and HO-1 were localized in the cytoplasm of tubules only. In conclusion, AA-induced acute renal injury was associated with impaired Nrf2 activation and expression of its downstream target genes in renal tissues. BARD prevented renal damage induced by AAI, and this renoprotective effect may be exerted by activating the Nrf2 signaling pathway and increasing expression of the downstream target genes.
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    • "The in vitro toxic effect of Aristolochia cymbifera extracts on MA104 cells (Figure 3) is similar to that observed in studies that report high toxicity of the Aristolochia genus to human kidney cells, which was associated with aristolochic acids (Chen et al. 2010). However, the checkerboard dilution test used in this study showed that lower extract concentrations improve the antibacterial activity of the mixture (see Additional file 1). "
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    ABSTRACT: The appearance of new antibiotic-resistant bacteria is a societal problem that requires the development of new alternative treatments. Therefore, this work evaluated the antibacterial activity of ethanolic (EHI), dichloromethanic (EDI) and hexanic (EHE) extracts from Aristolochia cymbifera stems and the combination of these extracts with an antimicrobial drug to develop a new antibacterial therapy. The EDI, EHE and EHI extracts were obtained by maceration using three different solvents. The minimal inhibitory concentrations (MIC) of these extracts were determined using the microdilution test to determine the antibacterial potential of these extracts and their combination with streptomycin against Staphylococcus aureus, Bacillus cereus, Klebsiella pneumoniae and Shigella flexneri. The extract dose leading to the cytotoxicity of 50% of the cells (CC50) was evaluated using mammalian cells MA104 and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. The extracts had a MIC under 500 mg/L and a CC50 lower than 50 mg/L. The antibiotic/extract proportion influenced the antibacterial activity of the mixtures, and the proportion that optimized the antibacterial activity of streptomycin was a mixture that contained 75 percent of extract. This composition included less than 6.5 mg/L of extract and 2.5 mg/L of streptomycin and has potential as a new antibacterial therapy. Electronic supplementary material The online version of this article (doi:10.1186/2193-1801-2-430) contains supplementary material, which is available to authorized users.
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