Transcriptional effects of organochlorine o,p -DDT and its metabolite p,p′-DDE in transfected MDA-MB 231 and MCF-7 breast cancer cell line

The organochlorine DDT has estrogenic activity but the mechanism underlying the estrogenic activity of this pesticide remains unclear. In the present investigation here, 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 line. Cells were seeded for transfections 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. The results showed o,p’-DDT has 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, The results obviously show that o,p’-DDT has 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. In addition, there is no agonistic effect with p,p''-DDE on transfected MCF-7 cells and MDA-MB 231 cell line. In conclusion, our results revealed that o,p’-DDT has not estrogenic activity in a classical mechanism in transfected MDA-MB 231 breast cancer cells while has estrogenic activity in a classical mechanism in transfected MCF-7 human breast cancer cell line.