The homeoprotein six1 transcriptionally activates multiple protumorigenic genes but requires ezrin to promote metastasis

Cancer Res. 2006 Feb 15;66(4):1982-9. doi: 10.1158/0008-5472.CAN-05-2360.

Abstract

The vast majority of deaths associated with cancer are a consequence of a complex phenotypic behavior, metastasis, by which tumor cells spread from their primary site of origin to regional and distant sites. This process requires the tumor cell to make numerous adjustments, both subtle and dramatic, to successfully reach, survive, and flourish at favorable secondary sites. It has been suggested that molecular mechanisms accounting for metastatic behavior can recapitulate those employed during embryogenesis. We have shown that the homeodomain transcription factor Six1, known to be required for normal development of migratory myogenic progenitor cells, is sufficient to promote metastatic spread in a mouse model of the pediatric skeletal muscle cancer rhabdomyosarcoma. Here, we report that Six1 is able to activate the expression of a set of protumorigenic genes (encoding cyclin D1, c-Myc, and Ezrin) that can control cell proliferation, survival, and motility. Although the role of Ezrin in cytoskeletal organization and adhesion has been well studied, the means by which its expression is regulated are poorly understood. We now show that the gene encoding Ezrin is a direct transcriptional target of Six1. Moreover, Ezrin is indispensable for Six1-induced metastasis and highly expressed in a panel of representative pediatric cancers. Our data indicate that Ezrin represents a promising therapeutic target for patients with advanced-stage rhabdomyosarcoma and perhaps other malignancies.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Cyclin D1 / biosynthesis
  • Cyclin D1 / genetics
  • Cytoskeletal Proteins / biosynthesis
  • Cytoskeletal Proteins / genetics*
  • Gene Expression Regulation, Neoplastic
  • Homeodomain Proteins / biosynthesis
  • Homeodomain Proteins / genetics*
  • Humans
  • Male
  • Mice
  • Mice, Nude
  • Neoplasm Metastasis
  • Proto-Oncogene Proteins c-myc / biosynthesis
  • Proto-Oncogene Proteins c-myc / genetics
  • RNA Interference
  • RNA, Small Interfering / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Rhabdomyosarcoma / genetics*
  • Rhabdomyosarcoma / pathology*
  • Transcriptional Activation
  • Transfection

Substances

  • Cytoskeletal Proteins
  • Homeodomain Proteins
  • Proto-Oncogene Proteins c-myc
  • RNA, Small Interfering
  • SIX1 protein, human
  • Six1 protein, mouse
  • ezrin
  • Cyclin D1