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.
| Original language | English |
|---|---|
| Pages (from-to) | 1549-1559 |
| Number of pages | 11 |
| Journal | Archives of Toxicology |
| Volume | 88 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - 2014 |
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Keywords
- Bladder cancer
- DNA methylation
- Epigenetic alterations
- Inorganic arsenic
- Lipocalin-2
- Urothelial cells
ASJC Scopus subject areas
- Toxicology
- Health, Toxicology and Mutagenesis
Cite this
Long-term low-dose exposure of human urothelial cells to sodium arsenite activates lipocalin-2 via promoter hypomethylation. / Wang, Hsiu Hua; Wu, Meei Maan; Chan, Michael W Y; Pu, Yeong Shiau; Chen, Chien Jen; Lee, Te Chang.
In: Archives of Toxicology, Vol. 88, No. 8, 2014, p. 1549-1559.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Long-term low-dose exposure of human urothelial cells to sodium arsenite activates lipocalin-2 via promoter hypomethylation
AU - Wang, Hsiu Hua
AU - Wu, Meei Maan
AU - Chan, Michael W Y
AU - Pu, Yeong Shiau
AU - Chen, Chien Jen
AU - Lee, Te Chang
PY - 2014
Y1 - 2014
N2 - 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.
AB - 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.
KW - Bladder cancer
KW - DNA methylation
KW - Epigenetic alterations
KW - Inorganic arsenic
KW - Lipocalin-2
KW - Urothelial cells
UR - http://www.scopus.com/inward/record.url?scp=84904979200&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84904979200&partnerID=8YFLogxK
U2 - 10.1007/s00204-014-1214-x
DO - 10.1007/s00204-014-1214-x
M3 - Article
VL - 88
SP - 1549
EP - 1559
JO - Archiv fur Toxikologie
JF - Archiv fur Toxikologie
SN - 0003-9446
IS - 8
ER -