Role of the integrin-linked kinase (ILK)/Rictor complex in TGFβ-1-induced epithelial-mesenchymal transition (EMT)

Oncogene. 2013 Jan 3;32(1):50-60. doi: 10.1038/onc.2012.30. Epub 2012 Feb 6.

Abstract

Epithelial-to-mesenchymal transition (EMT) causes fibrosis, cancer progression and metastasis. Integrin-linked kinase (ILK) is a focal adhesion adaptor and a serine/threonine protein kinase that regulates cell proliferation, survival and EMT. Elucidating the molecular mechanisms necessary for development and progression of human malignancies is critical to predict the most appropriate targets for cancer therapy. Here, we used transforming growth factor beta-1 (TGFβ-1) to promote EMT and migration in mammary epithelial cells. We demonstrate a requirement of ILK activity for TGFβ-1-mediated EMT in mammary epithelial cells. In addition to nuclear translocation of Snail and Slug, TGFβ-1 treatment also induced expression of the mammalian target of rapamycin complex 2 component Rictor and its phosphorylation on Thr1135. Interestingly, TGFβ-1 treatment also induced an interaction between ILK and Rictor. All of these TGFβ-1-induced processes were significantly suppressed by inhibiting ILK activity or by disrupting the ILK/Rictor complex using small-interfering RNA-mediated knockdown. Furthermore, we identified ILK/Rictor complex formation in cancer but not in normal cell types, and this was accompanied by ILK-dependent phosphorylation of Rictor on residue Thr1135. Inhibition of ILK partially reversed the basal mesenchymal phenotype of MDA-MB-231 cells and prevented EMT in MCF10A cells after TGFβ-1 treatment. These data demonstrate a requirement for ILK function in TGFβ-1-induced EMT in mammary epithelial cells and identify the ILK/Rictor complex as a potential molecular target for preventing/reversing EMT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / enzymology
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Carrier Proteins / metabolism*
  • Cell Line, Tumor
  • Epithelial Cells / enzymology
  • Epithelial Cells / metabolism
  • Epithelial-Mesenchymal Transition / physiology*
  • Female
  • Humans
  • Mammary Glands, Human / cytology
  • Mammary Glands, Human / enzymology
  • Mammary Glands, Human / metabolism*
  • Phosphorylation
  • Protein Serine-Threonine Kinases / metabolism*
  • RNA, Small Interfering
  • Rapamycin-Insensitive Companion of mTOR Protein
  • Transforming Growth Factor beta1 / physiology*

Substances

  • Carrier Proteins
  • RICTOR protein, human
  • RNA, Small Interfering
  • Rapamycin-Insensitive Companion of mTOR Protein
  • Transforming Growth Factor beta1
  • integrin-linked kinase
  • Protein Serine-Threonine Kinases