Effect of a negative regulatory element (NRE) on the human CYP1A1 gene expression in breast carcinoma MCF‐7 and hepatoma HepG2 cells

[摘要]

The expression of the cytochrome P4501A1 gene, CYP1A1, is induced by e.g. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) mainly by transcriptional mechanisms. The inducers mediate their effect upon binding and activation of the aryl hydrocarbon receptor (AHR) transcription-factor complex. Utilizing chimeric CYP1A1/HCAT constructs transient gene expression experiments indicate that the putative negative regulatory element (NRE) of CYP1A1 influence the relative TCDD induced CAT activity in HepG2 cells, whereas this effect was not observed in MCF-7 cells. Differences in the formation of cell-specific protein-DNA complexes were demonstrated by gel retardation assays suggesting a functional difference of NRE in these two cell lines.

[学科分类] 生物化学/生物物理

[关键词] P450IA1;Gene transcription;Negative regulatory element;Cell specificity;Human cell;TCDD;2;3;7;8-tetrachlorodibenzo-p-dioxin;AHR;aryl hydrocarbon receptor;CAT;chloramphenicol acetyl transferase;NRE;negative regulatory element;PAH;polycyclic aromatic hydrocarbons;AHH;aryl hydrocarbon hydroxylase;XRE or DRE;xenobiotic or dioxin response element;ARNT;AHR nuclear translocator;EMSA;electrophoretic mobility shift assay;SV40;simian virus 40;β-gal;β-galactosidase;FCS;fetal bovine serum;DMEM-PH;Dulbecco's Modified Medium without Phenol red;DMSO;dimethylsulfoxide;1deoxy14C-Cm;1-deoxy[dichloroacetyl-l-14C]chloramphenicol;DTT;dithiothreitol;RT;room temperature;HSV tk;herpes simplex virus thymidine kinase