J BIOCHEM MOLECULAR TOXICOLOGY Volume 26, Number 11, 2012 Differential Effect of DDT, DDE, and DDD on COX-2 Expression in the Human Trophoblast Derived HTR-8/SVneo Cells Pablo Dominguez-Lopez, 1 Laura Diaz-Cueto, 1 Aleida Olivares, 1 Alfredo Ulloa-Aguirre, 2 and Fabian Arechavaleta-Velasco 1 1 Research Unit in Reproductive Medicine, UMAE en Ginecologia y Obstetricia “Luis Castelazo Ayala.” IMSS, M´ exico D. F., Mexico; E-mail: fabian.arechavaleta@mac.com 2 Division of Reproductive Health, Research Center in Population Health, National Institute of Public Health, Cuernavaca, Morelos, Mexico Received 8 June 2012; accepted 14 August 2012 ABSTRACT: The purpose of this study was to investigate the effect of 1,1,1-trichloro-2,2-bis- (chlorophenyl)ethane (DDT), 1,1-bis-(chlorophenyl)- 2,2-dichloroethene (DDE), and 1,1-dichloro-2,2- bis(chlorophenyl)ethane (DDD) isomers on COX-2 expression in a human trophoblast-derived cell line. Cultured HTR-8/SVneo trophoblast cells were exposed to DDT isomers and its metabolites for 24 h, and COX-2 mRNA and protein expression were assessed by RT-PCR, Western blotting, and ELISA. Prostaglandin E 2 production was also measured by ELISA. Both COX-2 mRNA and protein were detected under control (unexposed) conditions in the HTR-8/SVneo cell line. COX-2 protein expression and prostaglandin E 2 production but not COX-2 mRNA levels increased only after DDE and DDD isomers exposure. It is concluded that DDE and DDD exposure induce the expression of COX-2 protein, leading to increased prostaglandin E2 production. Interestingly, the regulation of COX-2 by these organochlorines pesticides appears to be at the translational level. C  2012 Wiley Periodicals, Inc. J Biochem Mol Tox- icol 26:454–460, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.21444 KEYWORDS: Trophoblast; Cyclooxygenase-2; Organochlorines; DDT; Placenta Correspondence to: Fabian Arechavaleta-Velasco. Contract Grant Sponsor: Consejo Nacional de Ciencia y Tec- nologia (CONACYT), Mexico. Contract Grant Number: CB-2005-1/24119. C  2012 Wiley Periodicals, Inc. INTRODUCTION 1,1,1-Trichloro-2,2-bis-(chlorophenyl)ethane (DDT) is a broad-spectrum synthetic organochlorine in- secticide still used in some countries mainly to control the malaria disease vector. Technical-grade DDT contains the p,p’-DDT (1,1,1-trichloro-2,2-bis(p- chlorophenyl)ethane) and the o,p’-DDT (1,1,1-trichloro- 2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane) iso- mers. In biological systems, DDT isomers are converted slowly to DDE (1,1-bis-(chlorophenyl)- 2,2-dichloroethene) and DDD (1,1-dichloro-2,2- bis(chlorophenyl)ethane) in the liver by the cytochrome P450 system [1]. Both DDT and its metabolites are lipophilic and relatively resistant to environmental degradation, which allows both their persistence in the food chain and their accumulation in the adipose tissue [2]. Epidemiological data suggest an association be- tween these insecticides and adverse pregnancy outcomes, including spontaneous miscarriage and preterm labor, in both human and animals [3–7]. In- flammation due to an increase in prostaglandins (PGs) biosynthesis is a feature that has been consistently as- sociated with the pathogenesis of these obstetrics com- plications [8–12]. Cyclooxygenase (COX) is the rate-limiting enzyme in the biosynthesis of PGs. It is a bifunctional hemopro- tein that catalyzes the conversion of arachidonic acid to prostaglandin H2 (PGH2), the common precursor to PGs and thromboxanes [13]. Two isoforms of COX that catalyze the same reaction but differ mainly in their pat- tern of expression and regulation have been identified to date in eukaryotic cells. COX-1 is constitutively ex- pressed in most cells and tissues and is responsible for 454