Critical interactions between TGF-β signaling/ELF, and E-cadherin/β-catenin mediated tumor suppression

Document Type

Journal Article

Publication Date

3-23-2006

Journal

Oncogene

Volume

25

Issue

13

DOI

10.1038/sj.onc.1209211

Keywords

E-cadherin; ELF; Gastrointestinal cancer; Smad4; Spectrin

Abstract

Inactivation of the transforming growth factor-β (TGF-β) pathway occurs often in malignancies of the gastrointestinal (GI) system. However, only a fraction of sporadic GI tumors exhibit inactivating mutations in early stages of cancer formation, suggesting that other mechanisms play a critical role in the inactivation of this pathway. Here, we show a wide range of GI tumors, including those of the stomach, liver and colon in elf+/- and elf+/-/Smad4+/- mutant mice. We found that embryonic liver fodrin (ELF), a β-Spectrin originally identified in endodermal stem/ progenitor cells committed to foregut lineage, possesses potent antioncogenic activity and is frequently inactivated in GI cancers. Specifically, E-cadherin accumulation at cell-cell contacts and E-cadherin-β-catenin-dependent epithelial cell-cell adhesion is disrupted in elf+/- Smad4 +/- mutant gastric epithelial cells, and could be rescued by ectopic expression of full-length elf, but not Smad3 or Smad4. Subcellular fractionation revealed that E-cadherin is expressed mainly at the cell membrane after TGF-β stimulation. In contrast, elf+/- /Smad4+/- mutant tissues showed abnormal distribution of E-cadherin that could be rescued by overexpression of ELF but not Smad3 or Smad4. Our results identify a group of common lethal malignancies in which inactivation of TGF-β signaling, which is essential for tumor suppression, is disrupted by inactivation of the ELF adaptor protein. © 2006 Nature Publishing Group All rights reserved.

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