Thyroid hormone receptors mutated in liver cancer function as distorted antimorphs

I. H. Chan, M. L. Privalsky

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

Aberrant thyroid hormone receptors (TRs) are found in over 70% of the human hepatocellular carcinomas (HCCs) analysed. To better understand the role(s) of these TR mutants in this neoplasia, we analysed a panel of HCC mutant receptors for their molecular properties. Virtually all HCC-associated TR mutants tested retained the ability to repress target genes in the absence of T3, yet were impaired in T3-driven gene activation and functioned as dominant-negative inhibitors of wild-type TR activity. Intriguingly, the HCC TRα1 mutants exerted dominant-negative interference at all T3 concentrations tested, whereas the HCC TRβ1 mutants were dominant-negatives only at low and intermediate T3 concentrations, reverting to transcriptional activators at higher hormone levels. The relative affinity for the SMRT versus N-CoR corepressors was detectably altered for several of the HCC mutant TRs, suggesting changes in corepressor preference and recruitment compared to wild type. Several of the TRα HCC mutations also altered the DNA recognition properties of the encoded receptors, indicating that these HCC TR mutants may regulate a distinct set of target genes from those regulated by wild-type TRs. Finally, whereas wild-type TRs interfere with c-Jun/AP-1 function in a T3-dependent fashion and suppress anchorage-independent growth when ectopically expressed in HepG2 cells, at least certain of the HCC mutants did not exert these inhibitory properties. These alterations in transcriptional regulation and DNA recognition appear likely to contribute to oncogenesis by reprogramming the differentiation and proliferative properties of the hepatocytes in which the mutant TRs are expressed.

Original languageEnglish (US)
Pages (from-to)3576-3588
Number of pages13
JournalOncogene
Volume25
Issue number25
DOIs
StatePublished - Jun 15 2006

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Thyroid Hormone Receptors
Liver Neoplasms
Hepatocellular Carcinoma
Co-Repressor Proteins
DNA
Transcription Factor AP-1
Hep G2 Cells
Transcriptional Activation
Genes
Hepatocytes
Carcinogenesis
Hormones

Keywords

  • AP-1
  • c-Jun
  • DNA recognition
  • Dominant-negatives
  • Hepatocellular carcinoma
  • Nuclear hormone receptors

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research
  • Genetics

Cite this

Thyroid hormone receptors mutated in liver cancer function as distorted antimorphs. / Chan, I. H.; Privalsky, M. L.

In: Oncogene, Vol. 25, No. 25, 15.06.2006, p. 3576-3588.

Research output: Contribution to journalArticle

Chan, I. H. ; Privalsky, M. L. / Thyroid hormone receptors mutated in liver cancer function as distorted antimorphs. In: Oncogene. 2006 ; Vol. 25, No. 25. pp. 3576-3588.
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