Estrogenic Activity of Mineral Oil Aromatic Hydrocarbons Used in Printing Inks
Fig 1
Estrogenic effects of MOs in the E-screen, the hERα-HeLa-9903 assay and induction of ER responsive transcripts as indicated.
Proliferation assays with MCF-7 cells were performed subsequent to cellular stimulation with dispersions of 1 and 0.1 μl/ml MO (eq. to dil. of 1:1,000 and 1:10,000) or E2 as indicated (A). For the reporter gene assay hERα-HeLa-9903 cells were stimulated for 20 h with the indicated amounts of E2 or 1 μl/ml MO dispersed in medium, followed by cellular lysis and measurement of firefly luciferase activity (B). Transcriptional assays were following a 24-h exposure to 1 μl/ml MO or 10 nM E2, respectively (C). Data in all assays represent the mean ± SEM from at least three independent experiments. For the E-screen and the reporter gene assay data were corrected to accommodate the background of untreated cells and subjected to normalization using the effect of 1 nM E2. Likewise gene expression was normalized using RPLP0 and the solvent control as references. Abbreviations: PGR, progesterone receptor (gene); TFF1, trefoil factor (gene); GREB1, estrogen-dependent growth regulator in breast cancer 1 (gene).