Induction of cytochrome P4501A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin or indolo(3,2-b)carbazole is associated with oxidative DNA damage.

Induction of cytochrome P4501A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin or indolo(3,2-b)carbazole is associated with oxidative DNA damage.

Induction of cytochrome P4501A1 (CYP1A1) in the hepatoma Hepa1c1c7 cell line results in an elevation in the excretion rate of 8-oxoguanine (oxo8Gua), a biomarker of oxidative DNA damage and the major repair product of 8-oxo-2'-deoxyguanosine (oxo8dG) residues in DNA. Treatment of this cell line with 2,3,7,8-tetrachloro-p-dibenzodioxin (TCDD), a nonmetabolized environmental contaminant, and indo...

Arsenic inhibits induction of cytochrome P450 1A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin in human hepatoma cells.

The aim of this study was to examine the arsenic effect on activation of aryl hydrocarbon receptor (AhR)-mediated gene expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) in human hepatoma cells. The human hepatoma Huh7 cells were treated with sodium arsenite (NaAsO2) from 0.5 to 20 microM for 24 h. Our data revealed that NaAsO2 < or = 10 microM caused no significant cytotoxic effe...

Induction of cytochrome P4501A1.

Cytochrome P4501A1 is a substrate-inducible microsomal enzyme that oxygenates polycyclic aromatic hydrocarbons, such as the carcinogen benzo(a)pyrene, as the initial step in their metabolic processing to water-soluble derivatives. Enzyme induction reflects increased transcription of the cognate CYP1A1 gene. The environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin is the most potent known ...

2,3,7,8-Tetrachlorodibenzo-p-dioxin.

Arsenite inhibition of CYP1A1 induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin is independent of cell cycle arrest.

We show here that arsenite (As(3+)) elicits multiple effects on gene control, such as the interruption of cell cycle control by initiating G(2)/M arrest as well as inhibiting the aryl hydrocarbon (Ah) receptor-mediated 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible expression of CYP1A1. This raises the question as to whether As(3+) is selectively inhibiting TCDD induction of CYP1A1 indepe...