Characterization of the Ah Receptor Mediating Aryl Hydrocarbon Hydroxylase Induction in the Human Liver Cell Line Hep G2
Roberts, EA; Johnson, KC; Harper, PA; Okey, AB
| HERO ID | 2136796 |
|---|---|
| In Press | No |
| Year | 1990 |
| Title | Characterization of the Ah Receptor Mediating Aryl Hydrocarbon Hydroxylase Induction in the Human Liver Cell Line Hep G2 |
| Authors | Roberts, EA; Johnson, KC; Harper, PA; Okey, AB |
| Journal | Archives of Biochemistry and Biophysics |
| Volume | 276 |
| Issue | 2 |
| Page Numbers | 442-450 |
| Abstract | Ah receptor properties in human liver cells were examined. Sucrose gradient analysis was conducted by incubating 500 microliters of cytosolic preparations of human liver cell Hep-G2 with 10 nanomolar tritium labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin (1746016) (TCDD) for 1 hour. Competitors included TCDD, 2,3,7,8-tetrachlorodibenzofuran (51207319) (TCDF), 2,3,4,7,8-pentachlorodibenzofuran (57117314) (PCDF), 3-methylcholanthrene (56495) (MC), and dibenzo(a,h)anthracene (53703) (DBahA). Radioactivity in fractions collected from the gradient was determined by liquid scintillation counting. Nuclear translocation was assessed and aryl-hydrocarbon-hydroxylase (AHH) activity was measured with and without preincubation with benz(a)anthracene (BA) or MC. Mouse Hepa-1 cells were used for comparison. The concentration of Ah receptor binding sites for TCDD in Hep-G2 cells was 112 femtomoles per milligram (fmol/mg). The concentration in Hepa-1 cells was 422fmol/mg. In Hep-G2 cells, the TCDDh receptor complex sedimented at 9S on sucrose density gradients. TCDD/Ah receptor binding was completely inhibited by TCDF, PCDF, MC, and DBahA. Phenobarbital (50066), dexamethasone (50022), and estradiol (50282) had no effect. The dissociation constant for the TCDD/Ah receptor complex was 9 nanomolar by Wolf plot analysis; this value was about an order of magnitude weaker than that seen using Hepa-1 cells. Cytosolic and nuclear TCDD/Ah receptor complexes that sedimented at 9S and 6S, respectively, were detected after incubation of whole Hep-G2 cells. 3MC and BA induced AHH activity in Hep-G2 cells in a dose dependent manner. The concentrations causing half maximal induction (EC50s) were 1.3 and 5.3 micromolar (microM), respectively. The EC50 for induction of AHH activity by BAin Hepa-1 cells was 0.3microM. The authors conclude that Hep-G2 cells possess a drug metabolizing activity that is associated with cytochrome-P-450IA1 and at least part of the receptor mechanism needed to regulate it. |
| Doi | 10.1016/0003-9861(90)90743-i |
| Pmid | 2154949 |
| Wosid | WOS:A1990CN60200021 |
| Is Certified Translation | No |
| Dupe Override | No |
| Comments | Scopus URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-0025159425&doi=10.1016%2f0003-9861%2890%2990743-I&partnerID=40&md5=60ef72d68aa8df91dc2ce486607f5226 |
| Is Public | Yes |
| Language Text | English |