The effects of 2,3,7,8-Tetrachlorodibenzo-p-dioxin(TCDD), which is a well known pollutant, on apoptosis were examined in MCF-7 cells. TODD induced programmed cell death and inhibited Bcl-2 protein expression by suppressing the effect of Estrogen. Estrogen was known to activate the expression of Bcl-2 protein by binding ERE similar sequences. However, in the absence of Estrogen, TCDD inhibited apoptosis and induced Bcl-2 protein expression by binding DRE consensus sequences in Bcl-2 cDNA. DRE consensus sequence is needed for TCDD-AhR complex binding. The study implicates that TODD can regulate Bcl-2 protein expression and apoptosis.
