Rapamycin inhibits ezrin-mediated metastatic behavior in a murine model of osteosarcoma

Xiaolin Wan, Arnulfo Mendoza, Chand Khanna, Lee J. Helman

Research output: Contribution to journalArticlepeer-review

171 Scopus citations


Osteosarcoma is the most frequent primary malignant tumor of bone with a high propensity for metastasis. We have previously showed that ezrin expression is necessary for metastatic behavior in a murine model of osteosarcoma (K7M2). In this study, we found that a mechanism of ezrin-related metastatic behavior is linked to an Akt-dependent mammalian target of rapamycin (mTOK)/p70 ribosomal protein S6 kinase (S6K1)/eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) pathway. Suppression of ezrin expression either by antisense transfection or by small interfering RNAs or disruption of ezrin function by transfection of a dominant-negative ezrin-T567A mutant led to decreased expression and decreased phosphorylation of both S6K1 and 4E-BP1. Proteosomal inhibition by MG132 reversed antisense-mediated decrease of S6K1 and 4E-BP1 protein expression, but failed to affect the effect of ezrin on phosphorylation of S6K1 and 4E-BP1. Blockade of the mTOR pathway with rapamycin or its analog, cell cycle inhibitor-779 led to significant inhibition of experimental lung metastasis in vivo. These results suggest that blocking the mTOR/S6K1/4E-BP1 pathway may be an appropriate target for strategies to reduce tumor cell metastasis.

Original languageEnglish (US)
Pages (from-to)2406-2411
Number of pages6
JournalCancer Research
Issue number6
StatePublished - Mar 15 2005
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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