title: Enantioselective estrogenicity of o,p'-dichlorodiphenyltrichloroethane in the MCF-7 human breast carcinoma cell line.
abstract: Research increasingly suggests that selectivity between enantiomers may exist in acute and chronic toxicological effects of chiral contaminants. In this study, we used the human breast carcinoma MCF-7 cell line to evaluate enantioselectivity of o,p'-dichlorodiphenyltrichloroethane (o,p'-DDT). Baseline separation of o,p'-DDT enantiomers was achieved on the Chiralcel OJ chiral column by high-performance liquid chromatography, and the absolute configuration and optical rotation of the resolved enantiomers were further identified. Significant differences in estrogenic potential were observed between the two enantiomers of o,p'-DDT in the MCF-7 cell proliferation assay (i.e., the E-Screen assay) and the real-time quantitative polymerase chain reaction (PCR). In the E-Screen assay, the relative proliferative effect ratios of R-(-)-o,p'-DDT and S-(+)-o,p'-DDT were 89.4 and 27.9%, respectively, and the relative proliferative potency ratios were 0.1 and 0.001%, respectively. Compared to the solvent control, R-(-)-o,p'-DDT induced the maximal increase of 2.31-fold at a concentration of 10(-6) mol/L, while S-(+)-o,p'-DDT at 10(-5) mol/L induced the maximal increase of 1.65-fold in estrogenic biomarker pS2 mRNA level. The maximal down-regulation of the transcription levels of estrogen receptor alpha (ERa) and ER3 by R-(-)-o,p'-DDT were 49 and 40% at the concentration of 10(-6) mol/L, while those by S-(+)-o,p'-DDT were 24 and 26% at the concentration of 10(-5) mol/L. The cell proliferation, the up-regulation of pS2, and the down-regulation of ERalpha and ERbeta gene expressions induced by the racemate and enantiomers of o,p'-DDT were all reversed by cotreatment with 10(-6) mol/L ICI 182,780. Therefore, the enantioselective estrogenicity of o,p'-DDT was likely through the ERalpha and ERbeta signaling pathways. Results from this study suggest the need for considering enantioselectivity of chiral contaminants in chronic ecological toxicities.
authors.affiliation: Institute of Environmental Science, Zhejiang University, Hangzhou 310027, People's Republic of China. wliu@zjut.edu.cn
authors.forename: Lumei
authors.initials: L
authors.lastname: Wang
authors.forename: Shanshan
authors.initials: S
authors.lastname: Zhou
authors.forename: Kunde
authors.initials: K
authors.lastname: Lin
authors.forename: Meirong
authors.initials: M
authors.lastname: Zhao
authors.forename: Weiping
authors.initials: W
authors.lastname: Liu
authors.forename: Jianying
authors.initials: J
authors.lastname: Gan
mesh_terms: D001483:Base Sequence; D001943:Breast Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D003634:DDT / Q000737:chemistry / Q000633:toxicity*; D017931:DNA Primers; D004967:Estrogens / Q000633:toxicity*; D006801:Humans; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013237:Stereoisomerism
chemical_list: D017931:DNA Primers; D004967:Estrogens; D003634:DDT; C016340:o,p'-DDT