Identification of aryl hydrocarbon receptor as a putative Wnt/beta-catenin pathway target gene in prostate cancer cells

Cancer Res. 2004 Apr 1;64(7):2523-33. doi: 10.1158/0008-5472.can-03-3309.

Abstract

Recent genetic and functional analyses have implicated the wnt/beta-catenin signaling pathway in prostate cancer (CaP) pathogenesis. Thus, there is much interest in understanding the consequences of wnt signaling in CaP; target gene expression is one important area of inquiry and is the focus of this report. Adenoviral-mediated overexpression of a mutant, hyperactive form of beta-catenin in CWR22-Rv1 CaP cells led to increased aryl hydrocarbon receptor (AhR, or dioxin receptor) and transmembrane protein 2 RNA transcript expression, as detected by cDNA-microarray analyses. Validating these results, reverse transcription-PCR assays demonstrated that in CWR22-Rv1 cells as well as in LAPC-4 CaP cells, increased putative target gene RNA expression occurs with transient overexpression of mutant beta-catenin, treatment of cells with lithium chloride, or with wnt3a-conditioned medium, three distinct modes of experimental wnt/beta-catenin pathway activation. This beta-catenin-associated expression of AhR and transmembrane protein 2 does not require de novo protein synthesis and may only involve a certain subset of CaP cell lines. Western and immunofluorescence analyses were undertaken to assess the relationship between the wnt/beta-catenin-stimulated increase in AhR transcripts and AhR protein expression; we provide evidence that an association exists whereby up-regulation of AhR RNA by wnt or beta-catenin is coupled with augmented AhR protein levels. Intriguingly, these studies also demonstrated that nuclear beta-catenin staining may not be a sole deciding factor when predicting the status of wnt/beta-catenin signaling in CaP cells. Finally, the extent to which wnt signaling may synergize with an environmental agonist of AhR (2,3,7,8-tetrachlorodibenzo-p-dioxin) to potentiate AhR transcriptional activity was examined. Considering previous work linking AhR to processes of development and carcinogenesis, our data may highlight one particular role for wnt/beta-catenin signaling in prostate tumor biology.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cytoskeletal Proteins / genetics*
  • Gene Expression Regulation, Neoplastic / genetics
  • Humans
  • L Cells
  • Male
  • Mice
  • Oligonucleotide Array Sequence Analysis
  • Prostatic Neoplasms / genetics*
  • Proto-Oncogene Proteins / genetics*
  • Receptors, Aryl Hydrocarbon / agonists
  • Receptors, Aryl Hydrocarbon / biosynthesis
  • Receptors, Aryl Hydrocarbon / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / genetics
  • Trans-Activators / genetics*
  • Transcriptional Activation
  • Wnt Proteins
  • Zebrafish Proteins*
  • beta Catenin

Substances

  • CTNNB1 protein, human
  • CTNNB1 protein, mouse
  • Cytoskeletal Proteins
  • Proto-Oncogene Proteins
  • Receptors, Aryl Hydrocarbon
  • Trans-Activators
  • Wnt Proteins
  • Zebrafish Proteins
  • beta Catenin