Increase in AP-1 activity is a general event in thyroid cell transformation in vitro and in vivo

Oncogene. 1998 Jul 23;17(3):377-85. doi: 10.1038/sj.onc.1201953.


We have recently reported that neoplastic transformation of two rat thyroid epithelial cell lines by retroviruses carrying the v-mos and v-ras Ki oncogenes is associated with a drastic increase of AP-1 activity. The most important effects were represented by the dramatic junB and fra-1 gene induction, which was abolished by the block of the transformation-induced HMGI-C protein synthesis. Here, we have further characterized the transformation-dependent AP-1 activity, by analysing the expression of different jun- and fos-related components, in rat thyroid cell lines transformed by several oncogenes, in human thyroid carcinoma cell lines, and in naturally occurring human thyroid tumours. A significant increase of Fra-1 and JunB protein levels was detected in all oncogene transformed rat thyroid cell lines. Fra-1 gene induction was demonstrated to occur also in human thyroid carcinoma cell lines and tissues. Conversely, c-Jun and JunD proteins, rather than JunB, accumulated in human thyroid carcinoma cell lines. An induction of AP-1 target genes was also detected both in rat and human thyroid transformed cell lines. Therefore, in vivo and in vitro thyroid cell transformation is associated with important compositional changes in the AP-1 complex and an increased transcriptional activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Transformation, Neoplastic*
  • Epithelial Cells / metabolism
  • Epithelial Cells / pathology
  • Genes, jun
  • HMGA2 Protein
  • High Mobility Group Proteins / biosynthesis
  • Humans
  • Neoplasm Proteins / biosynthesis
  • Oncogenes*
  • Polymerase Chain Reaction
  • Proto-Oncogene Proteins c-fos / biosynthesis
  • Proto-Oncogene Proteins c-jun / biosynthesis
  • Rats
  • Thyroglobulin / biosynthesis
  • Thyroid Gland / metabolism*
  • Thyroid Gland / pathology
  • Thyroid Neoplasms / genetics*
  • Thyrotropin / pharmacology
  • Transcription Factor AP-1 / metabolism*


  • HMGA2 Protein
  • High Mobility Group Proteins
  • Neoplasm Proteins
  • Proto-Oncogene Proteins c-fos
  • Proto-Oncogene Proteins c-jun
  • Transcription Factor AP-1
  • fos-related antigen 1
  • Thyrotropin
  • Thyroglobulin