Unknown,Transcriptomics,Genomics,Proteomics

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DNA microarray analysis for HepG2 cells exposed to arsenic trioxide

ABSTRACT: DNA microarray analysis revealed that the genes related to cell cycle regulation were significantly induced at non- and sub-lethal concentrations (i.e., 0.05-6 M-BM-5M), while the common feature of heavy metal toxicity such as oxidative damage and following increase in glutathione, heat shock proteins, and metallothionein were confirmed at high concentrations (i.e., 6-40 M-BM-5M). The concentration dependent modulation of gene expression (induction of cell cycle genes, induction of cell cycle arrest genes and apoptotic genes) following exposure to arsenic was further supported by acceleration of cell proliferation, ROS generation, and cytotoxicity. Furthermore, three cell cycle genes (i.e., CDC25B, UBE2C, and PTTG1) were proposed as marker genes of inorganic arsenic exposure. Those results indicated the potential pro-carcinogenic actions of inorganic arsenic occur in environmentally relevant exposures (as low as 0.07 M-BM-5M). In this study, we examined the gene expression alteration in HepG2 cells exposed to arsenic trioxide (5 nM to 40 M-BM-5M as As2O3 for 48 hours) by DNA microarray with 8795 human genes. HepG2 cells were also exposed to M-NM-5-caprolactam as a reference of non carcinogen since it is the only chemical categorized in IARCM-bM-^@M-^Ys group 4 (Probably Not Carcinogenic). MQ water was used as control. For replicate, three dishes were prepared for each sample and individually treated in parallel.

ORGANISM(S): Homo sapiens

SUBMITTER: Hiroe Hara-Yamamura

PROVIDER: E-GEOD-48441 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Inorganic arsenic, a major environmental contaminant, has risen as an important health problem worldwide. More detailed identification of the molecular mechanisms associated with iAs exposure would help to establish better strategies for prevention and treatment. Although chronic iAs exposures have been previously studied there is little to no information regarding the early events of exposure to iAs. To better characterize the early mechanisms of iAs exposure we conducted gene expression studies using sublethal doses of iAs at two different time-points. The major transcripts differentially regulated at 2 hrs of iAs exposure included antioxidants, detoxificants and chaperones. Moreover, after 12 hrs of exposure many of the down-regulated genes were associated with DNA replication and S phase cell cycle progression. Interestingly, the most affected biological pathway by both 2 or 12 hrs of iAs exposure were the Nrf2-Keap1 pathway, represented by the highly up-regulated HMOX1 transcript, which is transcriptionally regulated by the transcription factor Nrf2. Additional Nrf2 targets included SQSTM1 and ABCB6, which were not previously associated with acute iAs exposure. Signalling pathways such as interferon, B cell receptor and AhR route were also responsive to acute iAs exposure. Since HMOX1 expression increased early (20 min) and was responsive to low iAs concentrations (0.1 M-oM-^AM--M), this gene could be a suitable early biomarker for iAs exposure. In addition, the novel Nrf2 targets SQSTM1 and ABCB6 could play an important and previously unrecognized role in cellular protection against iAs We used human lymphoblastoid cell line (CL-1), immortalized with Epstein-Barr virus. Cell cultures were propagated in RPMI media supplemented with 10% fetal bovine serum (FBS), L-glutammine 2 mM and antiobiotics penicillin and 10 mg/ml streptomycin) at 37M-BM-:C in an atmosphere of 5% CO2. In the case of primary cultures, 1% phytohemaglutinine were added. Cell cultures (1x106) were treated with 5M-BM-5M sodium arsenite for 2 and 12 hrs while control cultures were incubated with PBS. Nine biological replicates for each condition were used for microarray analysis. After iAs treatment, total RNA from each biological replicate was isolated with Trizol. From the 9 biological replicates performed on each condition, we generated 3 pools at a concentration of 300 ng/M-BM-5L, where each pool was processed to a single microarray platform.

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DNA microarray analysis for HepG2 cells exposed to arsenic trioxide

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