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Updated: Aug 24, 2026

RhoC GTPase Activation Assay
09:58

RhoC GTPase Activation Assay

Published on: August 22, 2010

Raf and RhoA cooperate to transform intestinal epithelial cells and induce growth resistance to transforming growth

Jianguo Du1, Bo Jiang, Robert J Coffey

  • 1Department of Pediatrics, Center for Cell and Vascular Biology, Columbus Children's Research Institute and Ohio State College of Medicine and Public Health, Columbus, Ohio 43205, USA.

Molecular Cancer Research : MCR
|May 14, 2004
PubMed

Insights

Co-expressing activated Raf and RhoA transforms intestinal cells, inducing resistance to growth inhibition. Blocking RhoA reduces some Ras-driven changes but doesn't fully reverse the transformed state or TGF-beta sensitivity.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Biology

Background:

  • Unregulated activation of the Ras/Raf/MAPK pathway drives oncogenic transformation.
  • Raf activation alone is insufficient for tumorigenic transformation in intestinal epithelial cells.
  • Identifying interacting pathways is crucial for understanding intestinal epithelial aberrant growth.

Purpose of the Study:

  • Investigate functional interactions between Raf and RhoA in intestinal epithelial cell transformation.
  • Determine if co-expression of activated Raf and RhoA induces a transformed phenotype.
  • Assess the role of RhoA in Ras-driven intestinal epithelial cell transformation and TGF-beta resistance.

Main Methods:

  • Utilized RIE-1 cells overexpressing activated Raf(22W) and activated RhoA(63L).
  • Assessed morphological transformation, soft agar colony formation, and tumor growth in nude mice.
  • Analyzed expression of cyclin D1, cyclooxygenase-2 (COX-2), and response to transforming growth factor (TGF)-beta.
  • Investigated the effect of dominant-negative RhoA(N19) on RIE-Ras(12V) cells.

Main Results:

  • Co-expression of activated Raf and RhoA led to morphological transformation, soft agar colony formation, tumor growth in vivo, and overexpression of cyclin D1 and COX-2.
  • Double transfectants exhibited resistance to TGF-beta-induced growth inhibition.
  • Single transfectants (Raf or RhoA alone) did not display these transformed characteristics.
  • Blocking RhoA signaling in RIE-Ras cells reduced COX-2 and prostaglandin E2 levels but did not reverse transformed morphology or TGF-beta sensitivity.

Conclusions:

  • Co-expression of activated Raf and RhoA is sufficient to induce transformation and TGF-beta resistance in intestinal epithelial cells.
  • RhoA signaling blockade partially reverses Ras-driven changes but is insufficient to fully reverse the transformed phenotype or restore TGF-beta sensitivity.
  • Additional Rho family members or alternate Ras effector pathways may be involved in reversing the Ras phenotype.

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