Project description:Arsenic (As) exposure is a significant worldwide environmental health concern. Low dose, chronic arsenic exposure has been associated with higher risk of skin, lung, and bladder cancer, as well as cardiovascular disease and diabetes. While arsenic-induced biological changes play a role in disease pathology, little is known about the dynamic cellular changes due to arsenic exposure and withdrawal. In these studies, we seek to understand the molecular mechanisms behind the biological changes induced by chronic low doses of arsenic exposure. We used a comprehensive approach involving chromatin structural studies and mRNA microarray analyses to determine how chromatin structure and gene expression patterns change in response to chronic low dose arsenic exposure and its subsequent withdrawal. Our results show that cells exposed to low doses of sodium arsenite have distinct temporal and coordinated chromatin, gene expression and miRNA changes that are consistent with differentiation and activation of multiple biochemical pathways. Most of these temporal patterns in gene expression are reversed when arsenic was withdrawn. However, some of the gene expression patterns remained altered, plausibly as a result of an adaptive response by these cells. Additionally, these gene expression patterns correlated with changes in chromatin structure, further solidifying the role of chromatin structure in gene regulatory changes due to arsenite exposure. Lastly, we show that arsenite exposure influences gene regulation both at the transcription initiation as well as at the splicing level. Thus our results suggest that general patterns of alternative splicing, as well as expression of particular gene regulators, can be indicative of arsenite-induced cell transformation. A total of eight (8) samples with two biological replicates under four separate conditions: wild-type treated with deionized H2O for 36 days (NT); chronic low-dose arsenic exposure of 1 uM of sodium arsenite (iAs-T) for 36 days; chronic arsenic exposure of 1 uM of sodium arsenite for 26 days followed by removal of sodium arsenite for 10 days, measured at day 36 (iAs-Rev); and chronic arsenic exposure of 1 uM of sodium arsenite for 26 days, followed by removal of sodium arsenite exposure for 10 days, followed by 1 uM of chronic sodium arsenite exposure for 10 days (measured at day 46) (iAs-Rev-T).
Project description:Epithelial-mesenchymal transition (EMT) is an important mechanism in carcinogenesis. To determine the mechanisms that are involved in the regulation of EMT is crucial to develop new biomarkers and therapeutic targets towards cancers. In this study, when TGFÃ1 and TNFa were used to induce EMT in human lung carcinoma A549 cells, we were surprised to find an increase in an epithelial cell tight junction marker, Claudin 1. We further identified that it was the TNFa and not the TGFÃ1 that induced the fibroblast-like morphology changes. TNFa also caused the increase in Claudin-1 gene expression and protein levels in Triton X-100 soluble cytoplasm fraction. Down-regulation of Claudin-1, using small interfering RNA (siRNA), inhibited 75% of TNFa-induced gene expression changes. Claudin-1 siRNA effectively blocked TNFa-induced molecular functional networks related to inflammation and cell movement. Wound-healing assay showed that Claudin-1 siRNA was able to significantly reduce TNF-enhanced cell migration. Furthermore, over expression of Claudin 1 with a Claudin 1-pcDNA3.1/V5-His vector enhanced cell migration. In conclusion, these observations indicate that Claudin 1 acts as a critical signal mediator in TNFa-induced gene expression and cell migration in human lung cancer cells. Further analyses of these cellular processes may be helpful in developing novel therapeutic strategies. 4 groups (with or without TNFα, control or Claudin 1 siRNA) of human lung adenocarcinoma A549 cells with 3 replicates per group.
Project description:Arsenic is a potent environmental toxin and a cause of numerous health problems. Most studies have assumed that arsenic-induced changes in mRNA levels result from effects on gene transcription. The influence of arsenic on post-transcriptional regulation, another important locus of gene expression control, has remained largely unexplored. To evaluate the prevalence of changes in mRNA stability in response to arsenic in human fibroblasts, we used microarray analyses to determine changes in steady state mRNA levels, and their decay rates, following 24 hour exposure to non-cytotoxic concentrations of sodium arsenite (1 µM). We conclude that arsenite modification of mRNA stability is relatively uncommon, but in some instances can result in significant changes in gene expression. Human BJ diploid foreskin fibroblasts were used in the study. The decay rates of transcripts were determined using actinomycin D to stop transcription after sodium arsenite or water treatment for 24 h. Actinomycin D was added into the culture medium at a final concentration of 5 µg/ml, and treated cells were then harvested at 0, 1, 2, 3 and 4 h for RNA extraction.
Project description:The aim of the experiment is to identify kinetic changes in host gene expression upon infection of A549 lung epithelial carcinoma cells with human corona virus HCoV-229E as compared to unifected cells. Negativ controls include infections with heat-inactivated virus. Positive controls include treatment of cells with human IL-1alpha (10ng/ml) for 1h. All experiments have been performed at 33°C which is required for sufficient viral entry/replication.
Project description:Comparison of expression profiles detected in A549 cells exposed to DMSO, TCDD, and BaP for 2w Exposure to persistent ligands of aryl hydrocarbon receptor (AhR) has been found to cause lung cancer in experimental animals and lung adenocarcinomas are often associated with enhanced AhR expression and aberrant AhR activation. In order to better understand the action of toxic AhR ligands in lung epithelial cells, we performed global gene expression profiling in order to analyse TCDD- induced changes in A549 transcriptome, and compare them with changes in transcriptome of A549 cells exposed to BaP for 2w.
Project description:Arsenic is methylated during its metabolism, thereby depleting the intracellular methyl donor S-adenosyl-methionine, which may lead to disturbances in DNA methylation patterns Cells were exposed to sodium arsenite (NaAsO2, Sigma) at concentrations of 0.08 M-BM-5M, 0.4 M-BM-5M and 2 M-BM-5M for 1, 2 and 8 weeks. A549 arsenic dose time response study.
Project description:Fresh peripheral blood mononuclear cells of four human donors were cultured together with either lung adenocarcinoma A549 cancer cells or A549-expressing H1N1 Sialidase cancer cells. These treatments induced the differentiation of donor cells into immunosuppressive MDSC-like cells, which were further subjected to bulk RNA sequencing. Computational analysis of RNA-Seq profiles of these cells was applied to understand the differences in their suppressive capacities.
Project description:We have employed whole genome microarray expression to distinguish the effect of Fumed Silica Nanoparticles on human alveolar epithelial A549 lung cells. Cells were exposed in vitro, and datasets of differentially expressed genes were identified for NPs versus control samples. NPs induced gene expression in A549 cells was measured at 24 hours and 72 hours after exposure. Minimum three independent experiments were performed for each experiment.