Effects of histone deacetylation and DNA methylation on the constitutive and TCDD-inducible expressions of the human CYP1 family in MCF-7 and HeLa cells.
Human CYP1A1, CYP1A2, and CYP1B1 mRNAs were constitutively expressed in MCF-7 (human breast carcinoma) cells and were extensively (6-12-fold) induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In contrast, in HeLa (human cervical adenocarcinoma) cells, CYP1A1 and CYP1B1 were induced by TCDD by up to 2-3-fold but CYP1A2 was not detected even when the cells were treated with TCDD. In the present study, the involvement of histone deacetylation and DNA methylation in the cell-specific inducibility of the human CYP1 family was investigated. The treatment of MCF-7 cells with trichostatin A (TSA), an inhibitor of histone deacetylase, and 5-aza-2'-deoxycitidine (AzaC), an inhibitor of DNA methylase, increased the constitutive expression level of CYP1A1, CYP1A2, and CYP1B1 by 2-3-fold. However, these treatments did not affect the levels of induction by TCDD. In HeLa cells, TSA and AzaC treatment increased the constitutive expression levels of CYP1A1 and CYP1B1. The induction of CYP1A2 was enhanced to a detectable level by TSA and AzaC even when the cells were not exposed to TCDD. Interestingly, pretreatment with TSA and AzaC increased the levels of CYP1A1, CYP1A2, and CYP1B1 induced by TCDD in HeLa cells. Furthermore, it was observed that TSA and AzaC treatment increased the constitutive expression level of AhR by 2-fold only in HeLa cells. To compare the methylation status of the 5'-flanking region of the human CYP1A1 gene including five XREs and the promoter region in MCF-7 and HeLa cells, the bisulfite-modified genes were amplified and sequenced. Since there was no remarkable difference in the methylation status within a -1.4 kb region of the human CYP1A1 gene, the methylation status in the CpG sites that exist in other regions of the human CYP1A1 gene might be involved in the cell-specific induction.
Nakajima
Miki
M
Division of Drug Metabolism, Faculty of Pharmaceutical Sciences, Kanazawa University, Takara-machi 13-1, Kanazawa 920-0934, Japan.
Iwanari
Masashi
M
Yokoi
Tsuyoshi
T
D024506:5' Flanking Region / Q000235:genetics; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis / Q000235:genetics; D001374:Azacitidine / Q000494:pharmacology; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000096:biosynthesis / Q000235:genetics; D065633:Cytochrome P-450 CYP1B1; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D003640:Dealkylation; D004785:Environmental Pollutants / Q000633:toxicity*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008745:Methylation; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013447:Sulfites / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D004785:Environmental Pollutants; D006657:Histones; D006877:Hydroxamic Acids; D000072317:Polychlorinated Dibenzodioxins; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D013447:Sulfites; C012589:trichostatin A; D004247:DNA; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2; D065633:Cytochrome P-450 CYP1B1; D001374:Azacitidine; C042345:hydrogen sulfite