Low-level arsenite induced gene expression in HEK293 cells

• Published in: Toxicology (Amsterdam) 2003-05, Vol.187 (1), p.39-48
• Main Authors: Zheng, Xing Hui, Watts, George S., Vaught, Skip, Gandolfi, A.Jay
• Format: Article
• Language: English
• Subjects: Arsenite; Arsenites - toxicity; Biological and medical sciences; cDNA microarray; Cell Line; Chemical and industrial products toxicology. Toxic occupational diseases; DNA, Complementary - analysis; Dose-Response Relationship, Drug; Down-Regulation; Gene Expression Profiling; Gene Expression Regulation - drug effects; Gene Expression Regulation - genetics; HEK293 cells; Heme Oxygenase (Decyclizing) - genetics; Humans; Medical sciences; Metals and various inorganic compounds; Multigene Family - genetics; Oligonucleotide Array Sequence Analysis; Oxidative Stress - genetics; Reverse Transcriptase Polymerase Chain Reaction; Sodium Compounds - toxicity; Toxicology; Up-Regulation
• ISSN: 0300-483X; 1879-3185
• DOI: 10.1016/S0300-483X(03)00025-8

Chronic, low-level exposure to arsenic frequently results in skin, lung, bladder, and kidney cancer. Since arsenic is primarily excreted via the kidney, this study focused on this target tissue. Gene array was used as a sensitive low-level monitor of the impact of arsenic on this target tissue. Arsenite [As(III)] was chosen as the chemical species of arsenic since As(III) species are touted as the cellular toxic form of arsenic . Human embryonic kidney cell line HEK293 cells were incubated with 1, 10, and 25 μM arsenite [As(III)] for 6 or 24 h. Total RNA from treated and control cells was isolated, reverse transcribed, and labeled with Cy3 or Cy5, and hybridized to a human cDNA microarray. Hybridizations were performed four times using independent total RNA preparations to ensure reproducibility. Raw data from 10 and 25 μM treated cells exposed for 6 h was normalized within, and between, hybridizations followed by identification of genes affected by arsenite exposure based on practical significance (2-fold change up or down) and reproducibility (affected in four of six measurements). In these studies, 20 genes (HMOX1, MT1E, or FOSL1, etc.) were up-regulated, and 19 genes (MYC, JAK1, or CENPE, etc.) were down-regulated. Genes identified at 10 and 25 μM arsenic exposure were then examined after 1 μM treatment for 6 or 24 h. Expression of affected genes showed a dose-dependent (1–25 μM) trend that was apparently not time-dependent (6 vs. 24 h). The affected genes indicate that even this realistic, low-level arsenite exposure was recognized by the HEK293 cells (e.g. metallothionein genes) and produced an oxidative stress (e.g. heme oxygenase gene). These affected genes were characterized as stress response genes, proto-oncogene, signaling molecules, transcription factors, chemokine receptors, proteolytic enzymes, ESTs, and unknown genes. These findings imply that arsenite induces complex cellular injury and the cellular adaptation to As(III) is associated with alterations in the expression of many genes.