E-cadherin inhibits nuclear accumulation of Nrf2: implications for chemoresistance of cancer cells

J Cell Sci. 2012 Mar 1;125(Pt 5):1284-95. doi: 10.1242/jcs.095422. Epub 2012 Feb 2.

Abstract

Nrf2 has an anti-carcinogenic effect. However, an increase in Nrf2 activity is also implicated in cancer chemoresistance. A switch from E-cadherin to N-cadherin affects the transdifferentiation and metastasis of cancer cells. In view of the key role of this switch in cancer malignancy, we investigated the regulatory effect of E-cadherin on Nrf2. In HEK293 cells, overexpression of E-cadherin inhibited the nuclear accumulation of Nrf2, and prevented Nrf2-dependent gene induction. GST pull-down and immunocytochemical assays verified the interaction between E-cadherin and Nrf2: E-cadherin bound the C-terminus of Nrf2, but not its N-terminus, which comprises the Neh2 domain responsible for phosphorylation of Ser40. Our finding that the mutation of Ser40 to alanine in Nrf2 did not affect the ability of E-cadherin to bind Nrf2 and repress target gene transactivation suggests that E-cadherin might not disturb the phosphorylation. Studies using mutant constructs of E-cadherin suggested that the β-catenin-binding domain contributes to the inhibitory effect of E-cadherin on Nrf2. Consistently, knockdown of β-catenin attenuated not only the effect of E-cadherin binding to Nrf2, but also Keap1-dependent ubiquitylation of Nrf2, and thereby increased Nrf2 activity, supporting the involvement of β-catenin in the interactions. Collectively, E-cadherin recruits Nrf2 through β-catenin, and assists the function of Keap1 for the inhibition of nuclear localization and transcriptional activity of Nrf2. In HepG2 cells, the loss of E-cadherin by either siRNA knockdown or treatment with TGFβ1 enhanced the constitutive or inducible activity of Nrf2, implying that chemoresistance of cancer cells upon the loss of E-cadherin might be associated with Nrf2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cadherins / genetics
  • Cadherins / metabolism*
  • Cell Adhesion
  • Cell Line
  • Cell Line, Tumor
  • Cell Transdifferentiation
  • Doxorubicin / pharmacology
  • Drug Resistance, Neoplasm*
  • Gene Expression Regulation, Neoplastic
  • HEK293 Cells
  • Hep G2 Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Kelch-Like ECH-Associated Protein 1
  • NF-E2-Related Factor 2 / biosynthesis
  • NF-E2-Related Factor 2 / metabolism*
  • Neoplasm Metastasis
  • Neoplasms / drug therapy*
  • Neoplasms / metabolism
  • Neoplasms / pathology*
  • Phosphorylation
  • RNA Interference
  • RNA, Small Interfering
  • Transcription, Genetic
  • Transcriptional Activation
  • Transforming Growth Factor beta1 / pharmacology
  • beta Catenin / genetics
  • beta Catenin / metabolism

Substances

  • Cadherins
  • Intracellular Signaling Peptides and Proteins
  • KEAP1 protein, human
  • Kelch-Like ECH-Associated Protein 1
  • NF-E2-Related Factor 2
  • NFE2L2 protein, human
  • RNA, Small Interfering
  • Transforming Growth Factor beta1
  • beta Catenin
  • Doxorubicin