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MiniSOX9, a dominant-negative variant in colon cancer cells

R Abdel-Samad1, H Zalzali, C Rammah

  • 1Institut de Génomique Fonctionnelle, Montpellier, France.

Oncogene
|February 8, 2011
PubMed

Insights

A novel truncated SOX9 variant, MiniSOX9, is overexpressed in colon cancer, inhibiting SOX9

Area of Science:

  • Oncology
  • Molecular Biology
  • Genetics

Background:

  • Aberrant pre-mRNA processing is implicated in human diseases, particularly cancer.
  • The SOX9 transcription factor exhibits anti-oncogenic properties in the colon, with its knockout leading to intestinal hyperplasia.
  • SOX9 activity is often diminished in colon cancer cells, suggesting the presence of inhibitory variants.

Purpose of the Study:

  • To identify SOX9 variants that impair SOX9 activity in colon cancer cells.
  • To investigate the role of a newly discovered truncated SOX9 variant, MiniSOX9, in colon cancer development.

Main Methods:

  • Real-time reverse transcriptase-PCR to quantify MiniSOX9 mRNA levels in tumor and normal tissues.
  • Immunohistochemistry to assess MiniSOX9 protein expression in colon cancer samples.
  • Functional assays to determine MiniSOX9's effect on SOX9 activity, protein kinase Cα promoter, and Wnt pathway.

Main Results:

  • A truncated SOX9 variant, MiniSOX9, resulting from intron retention, was identified.
  • MiniSOX9 mRNA and protein were significantly overexpressed in human colon tumors compared to normal tissues.
  • MiniSOX9 functions as a SOX9 inhibitor, represses protein kinase Cα promoter activity, and activates the canonical Wnt pathway.

Conclusions:

  • MiniSOX9 is an oncogenic variant of SOX9 implicated in colon cancer progression.
  • The overexpression of MiniSOX9 contributes to colon tumorigenesis by inhibiting SOX9 and activating oncogenic pathways.
  • These findings offer new insights into the dual role of the SOX9 locus in colon cancer.

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