Enantioselective estrogenicity of o,p'-dichlorodiphenyltrichloroethane in the MCF-7 human breast carcinoma cell line.
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.
Wang
Lumei
L
Institute of Environmental Science, Zhejiang University, Hangzhou 310027, People's Republic of China. wliu@zjut.edu.cn
Zhou
Shanshan
S
Lin
Kunde
K
Zhao
Meirong
M
Liu
Weiping
W
Gan
Jianying
J
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
D017931:DNA Primers; D004967:Estrogens; D003634:DDT; C016340:o,p'-DDT