Effects of cycloheximide on the induction of CYP1A1 gene expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in three human breast cancer cell lines

Treatment of MCF-7, MDA-MB-231 and Hs578-T human breast cancer cell lines with 10 -9 M 2,3,7,8-tetrachlorodibenzo-g-dioxin (TCDD) induces CYP1A1 gene expression in the MCF-7 but not in the MDA-MB-231 or Hs578-T cells. Pretreatment of the cells with 10 -5 M cycloheximide results in significantly increased P4501A1 mRNA levels in all three cells lines. However, in cells co-treated with 10 -5 M cycloheximide plus 10 -9 M TCDD, an induced response by TCDD was observed in the MCF-7 and MDA-MB-231 but not in Hs578-T cells