Regulation of cell-cell contact molecules and the metastatic phenotype of medullary thyroid carcinoma by the Raf-1/MEK/ERK pathway

Academic Article


  • Background: Medullary thyroid carcinoma (MTC) is highly metastatic. We have recently reported that activation of the Raf-1/MEK/ERK signaling pathway in MTC cells results in morphologic changes. We hypothesized that Raf-1-induced morphologic changes could be associated with alterations in cell-cell contact molecules, thereby affecting the metastatic potential of MTC cells. Methods: An estradiol (E2)-inducible Raf-1 MTC cell line (TT-raf) was utilized in this study. Western blot analysis was used to confirm the Raf-1/MEK/ERK pathway activation and to measure levels of essential cell-cell contact molecules. Assays for cell adhesion and migration were performed to investigate the cell motility. Results: E2 treatment of TT-raf cells resulted in the Raf-1/MEK/ERK pathway activation as evidenced by increased levels of phospho-MEK1/2 and -ERK1/2. This resulted in significant reductions in levels of essential cell-cell contact molecules including E-cadherin, β-catenin, and occludin. Importantly, activation of the Raf-1/ MEK/ERK pathway and the associated decrease in essential cell-cell contact molecules dramatically inhibited the abilities of adhesion and migration in MTC cells. Furthermore, treatment of Raf-1-activated cells with U0126, a specific inhibitor of MEK, abrogated these Raf-1-induced effects indicating that the suppression of the metastatic phenotype in MTC cells is a MEK-dependent pathway. Conclusion: These data suggest that the Raf-1/MEK/ERK pathway regulates essential cell-cell contact molecules and metastatic phenotype of MTC cells. Thus, these findings provide further insight into the key steps in the metastatic progression of MTC. © 2008 Mosby, Inc. All rights reserved.
  • Published In

  • Surgery  Journal
  • Digital Object Identifier (doi)

    Author List

  • Ning L; Kunnimalaiyaan M; Chen H
  • Start Page

  • 920
  • End Page

  • 925
  • Volume

  • 144
  • Issue

  • 6