Mutagenesis Advance Access originally published online on September 28, 2007
Mutagenesis 2007 22(6):403-408; doi:10.1093/mutage/gem035
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Arsenic salt-induced DNA damage and expression of mutant p53 and COX-2 proteins in SV-40 immortalized human uroepithelial cells
1Department of Pathology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan 2Department of Pathology, Kaohsiung Medical University Chung-Ho Memorial Hospital, Kaohsiung 807, Taiwan 3National Sun Yat-Sen University-Kaohsiung Medical University Joint Research Center, Kaohsiung 804, Taiwan 4Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan 5Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
Arsenic is widely distributed in the environment, and is a proven toxic and carcinogenic agent that is associated with various human malignancies, including bladder cancer. However, the mechanisms of its carcinogenic action are still not well understood. In addition, over-expression of mutant p53 and cyclooxygenase-2 (COX-2) frequently occurs in a variety of human malignancies. It is therefore of interest to study the genotoxicity of arsenic salts on human uroepithelial cells and the expression of oncoproteins p53 and COX-2. In this study, the relative genotoxicity of sodium arsenite was evaluated in SV-40 immortalized human uroepithelial cells (SV-HUC-1) using the alkaline comet assay. The expression of mutant p53 and COX-2 was also evaluated by immunocytochemistry and western blotting. Our results revealed that sodium arsenite was able to induce DNA damage, and that its genotoxicity is correlated with its concentration. In addition, the expression of mutant p53 increased in parallel with comet scores, and the maximal expression of mutant p53 was observed at 4 µM arsenite. Similarly, sodium arsenite stimulated a concentration-dependent increase in COX-2 expression. In conclusion, this study demonstrated that sodium arsenite is genotoxic to uroepithelial cells in vitro, and that it will induce expression of mutant p53 and COX-2 proteins, indicating a possible key event in carcinogenesis. This study provides us with knowledge of the relationship between p53 and COX-2 over-expression in arsenite-treated urothelial cells and suggests a potential therapeutic role of COX-2 inhibitors in human urothelial malignancies.
* To whom correspondence should be addressed. Department of Pathology, Kaohsiung Medical University Chung-Ho Memorial Hospital, No. 100, Tzyou 1st Road, Kaohsiung 807, Taiwan. Tel: +886 7 3208233; Fax: +886 7 3136681; Email: cychai{at}kmu.edu.tw
Received on June 13, 2007; revised on July 13, 2007; accepted on August 13, 2007.