Long-term low-dose exposure of human urothelial cells to sodium arsenite activates lipocalin-2 via promoter hypomethylation
Journal
Archives of Toxicology
Journal Volume
88
Journal Issue
8
Pages
1549-1559
Date Issued
2014
Author(s)
Abstract
We previously reported that the sustained exposure of human urothelial cells (HUCs) to low-dose sodium arsenite induces changes in the gene expression profile and neoplastic transformation. In this study, we used the HumanMethylation27 BeadChip to analyze genome-wide methylation profiles and 5-aza-2′-deoxycytidine to examine the involvement of promoter methylation in gene expression. Because the expression of lipocalin-2 (LCN2) was highly enhanced by promoter hypomethylation in inorganic arsenic (iAs)-HUCs cells as well as bladder cancer tissues, we further showed that mutations at the binding sequences for NF-κB and C/EBP-α significantly reduced LCN2 promoter activity. By chromatin immunoprecipitation assay, we demonstrated the significantly increased binding of RelA (p65) and NF-κB1 (p50) to the hypomethylated promoter of LCN2 in the iAs-HUCs. Furthermore, we also demonstrated that LCN2 overexpression was crucial for the neoplastic characteristics of the iAs-HUCs, such as enhanced anchorage-independent growth, resistance to serum deprivation and activation of NF-κB signaling. In addition, our results indicated that enhanced NF-κB activity in iAs-HUCs was via LCN2-mediated increase in intracellular iron and reactive oxygen species levels. Taken together, our results show that sustained low-dose arsenic exposure results in epigenetic changes and enhanced oncogenic potential via LCN2 overexpression. ? 2014 Springer-Verlag.
Subjects
Bladder cancer; DNA methylation; Epigenetic alterations; Inorganic arsenic; Lipocalin-2; Urothelial cells
SDGs
Other Subjects
arsenite sodium; CCAAT enhancer binding protein; deoxycytidine; immunoglobulin enhancer binding protein; neutrophil gelatinase associated lipocalin; 5 aza 2' deoxycytidine; acute phase protein; arsenite sodium; arsenous acid derivative; azacitidine; culture medium; immunoglobulin enhancer binding protein; LCN2 protein, human; lipocalin; oncoprotein; pollutant; protein binding; sodium derivative; anchorage independent growth; article; bladder cancer; chromatin immunoprecipitation; controlled study; DNA methylation; epigenetics; gene expression; gene mutation; human; human cell; priority journal; promoter region; sequence analysis; signal transduction; urothelium; analogs and derivatives; bladder tumor; cell line; cell proliferation; culture medium; culture technique; cytology; dose response; drug effects; gene silencing; genetic association; genetics; metabolism; pathology; pollutant; site directed mutagenesis; time; toxicity; urothelium; Acute-Phase Proteins; Arsenites; Azacitidine; Cell Culture Techniques; Cell Line; Cell Proliferation; Chromatin Immunoprecipitation; Culture Media, Serum-Free; DNA Methylation; Dose-Response Relationship, Drug; Environmental Pollutants; Gene Silencing; Genome-Wide Association Study; Humans; Lipocalins; Mutagenesis, Site-Directed; NF-kappa B; Promoter Regions, Genetic; Protein Binding; Proto-Oncogene Proteins; Sodium Compounds; Time Factors; Urinary Bladder Neoplasms; Urothelium
Publisher
Springer Verlag
Type
journal article