Biotechnology and Bioprocess Engineering 16: 400-406 (2011) DOI 10.1007/s12257-010-0173-1 The Effect of Environmental Micropollutant (DEET) on the Expression of Cell Cycle and Apoptosis Regulatory Proteins in Human Cells In S. Kim, Xianghao Ren, Jin-Soo Chang, Jin Wook Lee, Hye-Weon Yu, Sung-Jo Kim, Jung Sun Heo, Am Jang and Ho Jae Han Received: 31 May 2010 / Revised: 15 October 2010 / Accepted: 18 October 2010 © The Korean Society for Biotechnology and Bioengineering and Springer 2011 Abstract N,N-diethyl-m-toluamide (DEET) is an insect repellent used worldwide, and a common micropollutant in aquatic environments. However, few studies have addressed the molecular mechanism of DEET toxicity and its effects on cell growth and apoptosis. The purpose of this study was to investigate the effect of DEET on the expression of the cell cycle and apoptosis regulatory proteins in human BE(2)-M17 cells. The results showed that DEET signifi- cantly decreased the cell viability (40.6 ~ 68.9% of control) at concentrations of 500 ~ 4,000 mg/L. Also, DEET signifi- cantly decreased the expressions of CDK 2, CDK 4, and cyclin D1 (3.9 ~ 86.6% of control), at concentrations of 50 ~ 400 mg/L but from 100 mg/L for cyclin E. Furthermore, DEET significantly increased the expression of caspase-3 (223.1 ~ 1,770.6% of control), but significantly decreased Bcl-2 expression (46.1 ~ 86.3% of control) at all concen- trations tested. In conclusion, DEET partially affected the expression of CDK/cyclin molecules, but fully affected the expressions of caspase-3 and Bcl-2 in BE(2)-M17 cells. Keywords : insect repellent, DEET, environmental micro pollutant, cell cycle regulatory protein, apoptosis-related regulatory protein 1. Introduction N,N-diethyl- m-toluamide (DEET), a typical insect repellent, is used to protect humans from insects (Fig. 1). The repellent is used worldwide, and ~ 30% of people in the US were found to utilize DEET [1]. It is discharged into wastewater treatment plants through housing sewage and finally enters the aquatic environment mainly via wastewater treatment plant effluents [2]. DEET is normally found in influents and effluents of wastewater treatment plants [3], reclaimed wastewater [4], rivers [5], seawater [2], irrigation water [6], groundwater [7], and drinking water [8] at concentrations of 10 -6 ~ 10 -2 mg/L. The reason for the wide distribution of DEET in aquatic environments lies in the low elimination rate of this chemical by ultrafilter (UF) filtration, coagulation, chlorination, activated sludge treat- ment, and membrane bio-reactors (MBR), if ozonation, reverse osmosis (RO), and nanofiltration (NF) are not em- ployed [9-12]. The main reported adverse effect of DEET has been neurotoxicity [13-16], although dermatitis [17-20] and allergic reactions [21] have been reported after animal and human testing in vivo. Tisch et al. [22] studied cytotoxicity and DNA damage caused by DEET at the mg/L level in pri- mary human nasal mucosal cells during carcinogenicity Xianghao Ren Key Laboratory of Urban Stormwater System and Water Environment, Ministry of Education, School of Environment and Energy Engineering, Beijing University of Civil Engineering and Architecture, Beijing 100- 044, P. R. China In S. Kim * , Jin Wook Lee, Hye-Weon Yu, Sung-Jo Kim, Am Jang Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Korea E-mail: iskim@gist.ac.kr Jin-Soo Chang Molecular Biogeochemical Laboratory, Department of Biological and Chemical Engineering, Yianbian University of Science and Technology (YUST), Jilin 133-000, China Jung Sun Heo, Ho Jae Han Department of Veterinary Physiology, College of Veterinary Medicine, BK21 Biotherapy Human Resources Center, Chonnam National University, Gwangju 500-757, Korea Xianghao Ren Department of Environmental Engineering, Changwon National University, Changwon 641-773, Korea RESEARCH PAPER