抄録
Transcriptional regulation by estrogen receptor (ER) and progesterone receptor (PR) are related to proliferation and differentiation of breast cancer. On the other hand, it is speculated that polychlorinated biphenyl (PCB) is related to progression of breast cancer. In the present study, we analyzed the effect of PCB on the regulation of PR-mediated transcription. In MCF-7 cells, low dose of PCB activated PR/ progesterone response element (PRE) transcription. However, at higher concentrations, the transcriptional activities were gradually decreased to the level activated by agonist. In CV-1 cells, PCB suppressed PR/PRE transcription at higher concentrations. These results suggest that the nuclear factor(s) in MCF-7 cells may be related to the augmentation by PCB in MCF-7 cells. We cotransfected ER&alpha with PR/PRE into CV-1 cells. The transcription was slightly suppressed by PCB, suggesting that the effect of ER was excluded from the augmentation by PCB at lower concentrations. We confirmed that PCB that we used in the present study did not affect the cell death. To analyze the effect of PCB on bindings of cofactors to PR, we are currently performing a series of mammalian two-hybrid assays. In addition, we analyzed the effect of PCB on the proliferation of MCF-7 cells. The number of cells was induced by PCB. In conclusion, PCB may disrupt PR-mediated transcription in breast cancer cells. [J Physiol Sci. 2007;57 Suppl:S171]
