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A complex pattern of mutations and abnormal splicing of Smad4 is present in thyroid tumours

Davide Lazzereschi1, Francesco Nardi, Alessandra Turco

  • 1Department of Experimental Medicine and Pathology, I Faculty of Medicine, University of Rome 'La Sapienza', V.le Regina Elena 324, Rome 00161, Italy. davide.lazzereschi@uniroma1.it

Oncogene
|June 9, 2005
PubMed

Insights

Transforming growth factor-beta (TGF-β) signaling is impaired in thyroid tumors. Smad4 gene mutations and alternative splicing are frequent in these tumors, suggesting early involvement in tumorigenesis.

Area of Science:

  • Oncology
  • Molecular Biology
  • Genetics

Background:

  • Transforming growth factor-beta (TGF-β) signaling is crucial in cellular processes.
  • Impaired TGF-β sensitivity is observed in thyroid tumors.
  • The role of Mad Mother Against Decapentaplegic homolog 4 (Smad4) in thyroid tumorigenesis is largely unknown.

Purpose of the Study:

  • To investigate the frequency and nature of Smad4 alterations in thyroid tumors.
  • To correlate Smad4 mutations with Smad4 protein expression.
  • To identify Smad4 alternative splicing events in thyroid lesions.

Main Methods:

  • Analysis of 56 thyroid tumors (benign and malignant) for Smad4 mutations using PCR-SSCP and sequencing.
  • Immunohistochemistry (IHC) to assess Smad4 protein expression.
  • RNA expression analysis for alternative splicing in 29 tumors.

Main Results:

  • Smad4 alterations were found in 27% (15/56) of thyroid tumors.
  • Novel intragenic Smad4 mutations, including missense, silent, frameshift, and indel mutations, were identified, predominantly in the linker region.
  • Tumors with Smad4 mutations showed reduced or absent Smad4 protein expression by IHC.
  • Four tumor-associated Smad4 splice variants and three additional variants due to exon-exon rearrangements were detected.

Conclusions:

  • Smad4 is frequently mutated and aberrantly spliced in thyroid tumors.
  • These genetic and splicing alterations in Smad4 may play a role as an early event in thyroid tumorigenesis.
  • Further research is warranted to elucidate the functional impact of these Smad4 alterations on TGF-β signaling in thyroid cancer.

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