Tissue Tranglutaminase Regulates Interactions between Ovarian Cancer Stem Cells and the Tumor Niche

Cancer Res. 2018 Jun 1;78(11):2990-3001. doi: 10.1158/0008-5472.CAN-17-2319. Epub 2018 Mar 6.

Abstract

Cancer progression and recurrence are linked to a rare population of cancer stem cells (CSC). Here, we hypothesized that interactions with the extracellular matrix drive CSC proliferation and tumor-initiating capacity and investigated the functions of scaffold protein tissue transglutaminase (TG2) in ovarian CSC. Complexes formed by TG2, fibronectin (FN), and integrin β1 were enriched in ovarian CSC and detectable in tumors. A function-inhibiting antibody against the TG2 FN-binding domain suppressed complex formation, CSC proliferation as spheroids, tumor-initiating capacity, and stemness-associated Wnt/β-catenin signaling. Disruption of the interaction between TG2 and FN also blocked spheroid formation and the response to Wnt ligands. TG2 and the Wnt receptor Frizzled 7 (Fzd7) form a complex in cancer cells and tumors, leading to Wnt pathway activation. Protein docking and peptide inhibition demonstrate that the interaction between TG2 and Fzd7 overlaps with the FN-binding domain of TG2. These results support a new function of TG2 in ovarian CSC, linked to spheroid proliferation and tumor-initiating capacity and mediated through direct interactions with Fzd7. We propose this complex as a new stem cell target.Significance: These findings reveal a new mechanism by which ovarian CSCs interact with the tumor microenvironment, promoting cell proliferation and tumor initiation. Cancer Res; 78(11); 2990-3001. ©2018 AACR.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Cell Proliferation / physiology
  • Extracellular Matrix / metabolism
  • Female
  • Fibronectins / metabolism
  • GTP-Binding Proteins / metabolism*
  • Humans
  • Integrin beta1 / metabolism
  • Mice
  • Mice, Nude
  • Neoplasm Recurrence, Local / metabolism
  • Neoplastic Stem Cells / metabolism*
  • Ovarian Neoplasms / metabolism*
  • Signal Transduction / physiology
  • Transglutaminases / metabolism*
  • Wnt Signaling Pathway / physiology
  • beta Catenin / metabolism

Substances

  • Fibronectins
  • Integrin beta1
  • beta Catenin
  • transglutaminase 2
  • Transglutaminases
  • GTP-Binding Proteins