1.
Annas, Anita, et al.
(författare)
Differential response of cultured human umbilical vein and artery endothelial cells to Ah receptor agonist treatment : CYP-dependent activation of food and environmental mutagens
2000
Ingår i: Toxicology and Applied Pharmacology. - : Elsevier BV. - 0041-008X .- 1096-0333. ; 169:1, s. 94-101
Tidskriftsartikel (refereegranskat) abstract
In the present study, 7-ethoxyresorufin O-deethylase (EROD), 7,12-dimethylbenz[a]anthracene (DMBA)-hydroxylase, and covalent binding of H-3-labeled 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (H-3-Trp-P-1) and H-3-DMBA were examined in human umbilical vein endothelial cells (HUVEC) and human umbilical artery endothelial cells (HUAEC) exposed to the aryl hydrocarbon (Ah) receptor agonist beta -naphthoflavone (BNF) or vehicle only. The results revealed a marked induction of enzymatic activity in BNF-treated HUVEC compared with vehicle-treated cells, whereas no similar response was observed in BNF-treated HUAEC. EROD, DMBA hydroxylase, and covalent binding of H-3-Trp-P-1 and H-3-DMBA in BNF-treated HUVEC were reduced in the presence of the CYP1A inhibitor ellipticine. Addition of other CYP1A inhibitors ru-naphthoflavone, miconazole, 1-ethynylpyrene, 1-(1-propynyl)pyrene, or the CYP1A substrate ethoyresorufin to the incubation buffer of BNF-treated HUVEC reduced covalent binding of H-3-Trp-P-1 by 93-98%. Western blot analysis confirmed an induction of CYP1A1 in BNF-treated HUVEC, but not in BNF-treated HUAEC. CYP1A1 was, however, detected in both vehicle- and BNF-treated HUAEC. The results showed that BNF exposure induced CYP1A1 and metabolic activation of xenobiotics in HUVEC, whereas the catalytic activity remained low in BNF-treated HUAEC. Our results suggest that endothelial lining of human veins may be a target for adverse effects of xenobiotics activated into reactive metabolites by Ah receptor-regulated enzymes. Several studies have detected CYP1A1 in endothelial linings, whereas expression of CYP1A2 and CYP1B1 seems to be negligible at this site. This suggests that the metabolic activation and covalent binding of H-3-Trp-P-1 and H-3-DMBA in HUVEC are most likely mediated by CYP1A1.
2.
Annas, Anita
(författare)
Metabolism-dependent activation of food and environmental mutagens in endothelial cells
2000
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
The endothelial cells of blood vessels have been proposed as a target for toxic effects ofxenobiotics in the cardiovascular system. In the present studies, induction of cytochromeP450 1A (CYP1A) enzymes and metabolic activation of food and environmentalmutagens were examined in endothelial cells of rodents, birds, and humans. Theheterocyclic amine 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and thepolycyclic aromatic hydrocarbons 7,12-dimethylbenz[a]anthracene (DMBA) andbenzo[a]pyrene were used as models for food and environmental mutagens.The results showed that Trp-P-1 was activated into tissue-binding metabolites in endothelial cells, preferentially of capillaries and veins, in rodents pretreated with the aryl hydrocarbon (Ah) receptor agonist β-naphthoflavone (BNF), whereas similar activationdid not occur in vehicle-treated animals. Similarly, exposure to BNF increased the tissue-binding of Trp-P-1 and DMBA in cultured human umbilical vein endothelial cells (HUVEC), as compared with vehicle-treated cells. In contrast, exposure to BNF did not increase the binding of the mutagens in human umbilical artery endothelial cells (HUAEC). The formation of reactive metabolites of Trp-P-1 and DMBA correlated with induction of CYP1A1 protein and/or CYP1A-dependent catalytic activities, such as 7-ethoxyresorufin O-deethylase (EROD) and DMBA hydroxylase, in endothelial cells of rodents and cultured HUVEC. Moreover, exposure to BNF increased the activation ofbenzo[a]pyrene into genotoxic metabolites in HUVEC as compared with vehicle-treated cells.In chicken and eider duck embryos, BNF induced EROD and activation of Trp-P-1 to tissue binding metabolites in the endothelial linings, preferentially of capillaries and veins, in heart and chorioallantoic membrane (CAM). In vehicle-treated embryos, these activities were low.Overall, the present studies show that CYP1A-dependent activation of xenobiotics into tissue binding or genotoxic metabolites can be induced in blood vessel endothelia in various species following exposure to Ah receptor agonists. The results also show that there is a differential response to Ah receptor agonists within the vascular tree; CYP1A and enzymatic activities are preferentially induced in endothelial cells of veins and capillaries, and to lesser extent in arteries. The results suggest that certain endothelial cellsmay be targets for CYP1A-dependent activation of xenobiotics in individuals exposed to Ah receptor agonists.
