Project description:Exposure to aristolochic acid (AA) is linked to kidney disease and urothelial cancer in humans. The major carcinogenic component of the AA plant extract is aristolochic acid I (AAI). The transcription factor p53 acts as a tumour suppressor and is frequently mutated in AA-induced tumours. Using a mouse model, we previously showed that Trp53 genotype impacts on AAI-induced nephrotoxicity in vivo (i.e. p53 protects from AAI-induced renal proximal tubular injury), but the underlying mechanism(s) involved remain to be further explored. In the present study, we investigated the impact of p53 on AAI-induced gene expression in vivo by treating Trp53(+/+), Trp53(+/-) and Trp53(-/-) mice with 3.5 mg/kg body weight (bw) AAI daily for 6 days. The Clariom™ S Assay microarray was used to elucidate gene expression profiles in mouse kidneys after AAI treatment in order to identify potential mechanisms by which AAI drives renal injury in Trp53(-/-) kidneys. Principle component analysis and hierarchical clustering in Qlucore Omics Explorer showed that gene expression in AAI-exposed Trp53(+/+), Trp53(+/-) and Trp53(-/-) kidneys is treatment-dependent. However, gene expression profiles did not segregate in a clear-cut manner according to Trp53 genotype, hence further investigations were performed by pathway analysis with MetaCore™. Several pathways, such as those related to epithelial-to-mesenchymal transition, transcription of hypoxia-inducible factor 1 targets, renal injury and secretion of xenobiotics were significantly altered to varying degrees for AAI-exposed kidneys. The top ten up-regulated genes included cyclin-dependent kinase inhibitor 1a (Cdkn1a), a mediator of cell cycle arrest; and neutrophil gelatinase-associated lipocalin (Ngal), which has been shown to play a role in nephritis by promoting inflammation and apoptosis. Members of the solute carrier (Slc) family (i.e. Slc22a2, Slc22a6, Slc22a7, Slc22a8) were amongst the top ten down-regulated genes. Pathway analysis also identified genes that are uniquely affected by AAI treatment in Trp53(+/+), Trp53(+/-) and Trp53(-/-) kidneys. Apoptotic pathways were modulated in Trp53(+/+) kidneys; whereas oncogenic and pro-survival pathways were significantly altered for Trp53(+/-) and Trp53(-/-) kidneys, respectively. Microarray gene expression analysis identified significant toxicogenomic responses to AAI that give novel insights into its mechanism of nephrotoxicity. Alterations of biological processes by AAI in Trp53(+/+), Trp53(+/-) and Trp53(-/-) kidneys could explain the mechanisms by which p53 protects from or p53 loss drives AAI-induced renal injury in vivo.
Project description:Aristolochic acid (AA) is a nephrotoxic carcinogen responsible for acute kidney injury, chronic renal failure, and associated urothelial cancers. This study aims to determine the genes in xenobiotic metabolism pathway regulated by AA and clarify the molecular mechanism underlying their action.
Project description:The proximal tubule is particularly susceptible to acute kidney injury caused by ischemic or toxic insults, due to its high oxygen demand, and role in excreting drugs such as DNA-damaging chemotherapeutics. AKI triggers PT cell de-differentiation, expression or pro-inflammatory and pro-fibrotic signaling molecules, and a dramatic shift in PT cell metabolism with severe suppression of fatty acid oxidation. The aim of this study was to investigate the transcriptional changes that occur in the S2 and S3 segments of the PT in response to the DNA damaging agent aristolochic acid I (AAI).
Project description:Exposure to aristolochic acid (AA) is linked to kidney disease and urothelial cancer in humans. The major carcinogenic component of the AA plant extract is aristolochic acid I (AAI). The tumour suppressor p53 is frequently mutated in AA-induced tumours. We previously showed that p53 protects from AAI-induced renal proximal tubular injury, but the underlying mechanism(s) involved remain to be further explored. In the present study, we investigated the impact of p53 on AAI-induced gene expression by treating Trp53(+/+), Trp53(+/-), and Trp53(-/-) mice with 3.5 mg/kg body weight (bw) AAI daily for six days. The Clariom™ S Assay microarray was used to elucidate gene expression profiles in mouse kidneys after AAI treatment. Analyses in Qlucore Omics Explorer showed that gene expression in AAI-exposed kidneys is treatment-dependent. However, gene expression profiles did not segregate in a clear-cut manner according to Trp53 genotype, hence further investigations were performed by pathway analysis with MetaCore™. Several pathways were significantly altered to varying degrees for AAI-exposed kidneys. Apoptotic pathways were modulated in Trp53(+/+) kidneys; whereas oncogenic and pro-survival pathways were significantly altered for Trp53(+/-) and Trp53(-/-) kidneys, respectively. Alterations of biological processes by AAI in mouse kidneys could explain the mechanisms by which p53 protects from or p53 loss drives AAI-induced renal injury in vivo.
Project description: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.
Project description:Aristolochic acid (AA) is a major ingredient in several Chinese herbs that exhibits a wide range of pharmacological effects. Recently, clinical reports and experimental studies have demonstrated that AA causes renal toxicities, acute renal failure and interstitial fibrosis.However, the molecular mechanism underlying AA nephrotoxicity is not yet fully understood. Embryonic stem cells (ESCs) are pluripotent cells isolated from early embryos, which have highly undifferentiated potential and are capable of differentiating into all kinds of body tissues and organs. It has been reported that ESCs are sensitive to drug stimulation, and thus may serve as important tools for in vitro assessment of drug toxicity. We aimed to identify accurate biomarkers of AA-induced renal toxicity on ESCs. Genomics analysis was performed to screen the changes in gene expression levels of ESCs following treatment with AA, in order to determine the potential biological processes in which AA induces renal toxicity.
Project description:This study looks at signatures of Aristolochic Acid mutagenesis in bladder cancer, based on exome and whole genome sequencing data. Thirteen bladder tumors and their matched normal DNAs were sequenced on Illumina platforms. Among them eleven were exome sequenced and two were whole genome sequenced.