Evidence that 2,3,7,8-tetrachlorodibenzo-p-dioxin induces NADPH cytochrome c (P-450) reductase in rat hepatoma cells in culture.
The lack of aryl hydrocarbon (benzo[a]pyrene) hydroxylase (AHH) (EC 1.14.14.1) induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in a clone of rat hepatoma (HTC cl-1) cells is not caused by the lack of nuclear Ah receptor or by a deficiency in the activity of NADPH-cytochrome c (P-450) reductase. Treatment of HTC cl-1 cell line with TCDD for 18 h in culture resulted in a reproducible 500-600% increase in reductase activity without concomitant expression in AHH activity. These data suggests that TCDD induces cytochrome c reductase activity and that the lack of inducible AHH activity in rat hepatoma cells could reflect a defect in the structural gene (s) encoding for cytochrome P1-450, or an Ah receptor with a faulty DNA binding domain.
Manjunath
G S
GS
Department of Biological Sciences, University of Windsor, Ontario, Canada.
Dufresne
M J
MJ
D000818:Animals; D003579:Cytochrome Reductases / Q000096:biosynthesis*; D004147:Dioxins / Q000494:pharmacology*; D004790:Enzyme Induction; D008114:Liver Neoplasms, Experimental; D051379:Mice; D009245:NADH Dehydrogenase / Q000096:biosynthesis*; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors; D014407:Tumor Cells, Cultured
D004147:Dioxins; D000072317:Polychlorinated Dibenzodioxins; D003579:Cytochrome Reductases; D009245:NADH Dehydrogenase