Downregulation of aryl hydrocarbon receptor function and cytochrome p450 1A1 induction by expression of Ha-ras oncogenes

John J. Reiners, Carol L. Jones, Nancy Hong, Russell E. Clift, Cornelis Elferink

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

The immortalized human epithelial cell line MCF10A has the phenotypic characteristics of normal breast cells. Exposure of MCF10A cultures to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) stimulated the transcriptional activation of cytochrome P450 1A1 (CYP1A1), and CYP1B1, and NAD(P)H:quinone oxidoreductase. Northern blot hybridization and nuclear run-on assays demonstrated that transcriptional activation of these genes was suppressed in stably transfected cultures expressing an Ha-ras oncogene (the MCF10A-NeoT line). Similar suppression did not occur in stably transfected lines carrying the expression vector or a normal c-Ha-ras protooncogene. Western blot analyses and immunofluorescence microscopy demonstrated that the lack of inducibility in MDF10A-NeoT cells reflected neither reductions in aryl hydrocarbon receptor (AHR) and aryl hydrocarbon nuclear translocator protein nor prevention of TCDD-induced AHR translocation to the nucleus. Suppression did correlate with reductions in DNA-AHR complex formation, as analyzed by gel retardation assays of soluble cell extracts treated in vitro with TCDD. The induction of Cyp1a-1 by TCDD was also analyzed in transgenic mice that expressed a v-Ha-ras oncogene exclusively in their keratinocytes. Relative to littermates lacking the transgene, the induction of Cyp1a-1 by TCDD was partially suppressed (about 50%) in the epidermises of v-Ha-ras-positive transgenic mice. However, normal levels of Cyp1a-1 induction occurred in the livers of the same mice. Induction of Cyp1a-1 by TCDD was also suppressed (more than 98%) in chemically induced skin papillomas having Ha-ras mutations, relative to uninvolved surrounding skin. These studies suggest that the p21-ras protein controls signal transduction pathways capable of modulating AHR function.

Original languageEnglish (US)
Pages (from-to)91-100
Number of pages10
JournalMolecular Carcinogenesis
Volume19
Issue number2
DOIs
StatePublished - 1997
Externally publishedYes

Fingerprint

Aryl Hydrocarbon Receptors
ras Genes
Cytochrome P-450 Enzyme System
Down-Regulation
Transgenic Mice
Transcriptional Activation
Aryl Hydrocarbon Receptor Nuclear Translocator
Proto-Oncogene Proteins p21(ras)
ras Proteins
Skin
Papilloma
Electrophoretic Mobility Shift Assay
Nuclear Proteins
Cell Extracts
Transgenes
Keratinocytes
Fluorescence Microscopy
Epidermis
Northern Blotting
NAD

Keywords

  • 2,3,7,8-tetrachlorodibenzo-p-dioxin
  • Cytochrome P450
  • Mammary gland

ASJC Scopus subject areas

  • Cancer Research
  • Molecular Biology

Cite this

Downregulation of aryl hydrocarbon receptor function and cytochrome p450 1A1 induction by expression of Ha-ras oncogenes. / Reiners, John J.; Jones, Carol L.; Hong, Nancy; Clift, Russell E.; Elferink, Cornelis.

In: Molecular Carcinogenesis, Vol. 19, No. 2, 1997, p. 91-100.

Research output: Contribution to journalArticle

Reiners, John J. ; Jones, Carol L. ; Hong, Nancy ; Clift, Russell E. ; Elferink, Cornelis. / Downregulation of aryl hydrocarbon receptor function and cytochrome p450 1A1 induction by expression of Ha-ras oncogenes. In: Molecular Carcinogenesis. 1997 ; Vol. 19, No. 2. pp. 91-100.
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