transcriptional effects of organochlorine o,p′-ddt and its metabolite p,p′-dde in transfected mda-mb 231 and mcf-7 breast cancer cell lines

Background: the organochlorine ddt has estrogenic activity but the mechanism underlying the estrogenic activity of this pesticide remains unclear. in the present investigation, we studied the transcriptional effects of a synthetic organochlorine pesticide o,p′-ddt [1.1.1.-trichloro-2-(o-chlorophenyl)-2-p-chloriphenyl ethane] and its metabolite p,p'-dde (2-2-bis(4/chlorophenyl)-1-1-dichloroethyl) on the bovine oxytocin and the thymidine kinase-ere promoter by estrogen receptor α in mda-mb 231 and mcf-7 breast cancer cell lines. materials and methods: cells were seeded for transfection into 12- well plates at a density of 100000 cells per well and were transfected with a total of 3 μg of plasmid dna using calcium phosphate coprecipitation. o,p′-ddt and p,p'-dde were used for stimulation of transfected mda-mb 231 and mcf-7 breast cancer cell lines. results: o,p′-ddt showed no agonistic activity in mda-mb 231 cells transfected with the oxytocin promoter construct (otwt) or the thymidine kinase-ere promoter construct (tk ere) and estrogen receptor α. while, we found o,p′-ddt with an agonistic effect on both the oxytocin and the thymidine kinase-ere promoter in mcf-7 leading to a more than two-fold stimulation of transcription at 10-5 m. moreover, there was no agonistic effect with p,p'-dde on transfected mcf-7 cells and mda-mb 231 cell lines. conclusion: in conclusion, o,p′-ddt was not found to have any estrogenic activity in a classical mechanism in transfected mda-mb 231 breast cancer cells while it showed estrogenic activity in a classical mechanism in transfected mcf-7 human breast cancer cell line.