Evidence that 2,3,7,8-tetrachlorodibenzo-p-dioxin induces NADPH cytochrome c (P-450) reductase in rat hepatoma cells in culture |
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| Authors: | G S Manjunath M J Dufresne |
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| Institution: | Department of Biological Sciences, University of Windsor, Ontario, Canada. |
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| Abstract: | The lack of aryl hydrocarbon (benzoa]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. |
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