FOXL2, GATA4, and SMAD3 co-operatively modulate gene expression, cell viability and apoptosis in ovarian granulosa cell tumor cells

PLoS One. 2014 Jan 9;9(1):e85545. doi: 10.1371/journal.pone.0085545. eCollection 2014.

Abstract

Aberrant ovarian granulosa cell proliferation and apoptosis may lead to granulosa cell tumors (GCT), the pathogenesis of which involves transcription factors GATA4, FOXL2, and SMAD3. FOXL2 gene harbors a point mutation (C134W) in a vast majority of GCTs. GATA4 is abundantly expressed in GCTs and its expression correlates with poor prognosis. The TGF-β mediator SMAD3 promotes GCT cell survival through NF-κB activation, and interacts with FOXL2. Here, we find that the expression patterns of these factors overlap in the normal human ovary and 90 GCTs, and positively correlate with each other and with their mutual target gene CCND2, which is a key factor for granulosa cell proliferation. We have explored the molecular interactions of FOXL2, GATA4, and SMAD3 and their roles in the regulation of CCND2 using co-immunoprecipitation, promoter transactivation, and cell viability assays in human GCT cells. We found that not only SMAD3, but also GATA4 physically interact with both wild type and C134W-mutated FOXL2. GATA4 and SMAD3 synergistically induce a 8-fold increase in CCND2 promoter transactivation, which is 50% reduced by both FOXL2 types. We confirmed that wild type FOXL2 significantly decreases cell viability. Interestingly, GATA4 and SMAD3 caused a marked reduction of GCT cell apoptosis induced by wild type FOXL2. Thus, the effects of GATA4 and SMAD3 on both cell viability and apoptosis are distinct from those of wild type FOXL2; a perturbation of this balance due to the oncogenic FOXL2 mutation is likely to contribute to GCT pathogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / genetics*
  • Cell Count
  • Cell Survival / genetics
  • Cyclin D2 / genetics
  • Cyclin D2 / metabolism
  • Female
  • Forkhead Box Protein L2
  • Forkhead Transcription Factors / metabolism*
  • GATA4 Transcription Factor / metabolism*
  • Gene Expression Regulation, Neoplastic*
  • Granulosa Cell Tumor / genetics*
  • Granulosa Cell Tumor / pathology*
  • Humans
  • Neoplasm Recurrence, Local / genetics
  • Neoplasm Recurrence, Local / pathology
  • Promoter Regions, Genetic / genetics
  • Protein Binding
  • Smad3 Protein / metabolism*
  • Transcription, Genetic
  • Transcriptional Activation / genetics

Substances

  • CCND2 protein, human
  • Cyclin D2
  • FOXL2 protein, human
  • Forkhead Box Protein L2
  • Forkhead Transcription Factors
  • GATA4 Transcription Factor
  • GATA4 protein, human
  • SMAD3 protein, human
  • Smad3 Protein

Supplementary concepts

  • Granulosa cell tumor of the ovary

Grant support

Financial support: Academy of Finland, Helsinki University Central Hospital Research Funds, Sigrid Juselius Foundation, Institut Universitaire de France, La Ligue Nationale Contre le Cancer (Comité’ de Paris), Groupement d'Entreprises Francaises dans la Lutte contre le Cancer (GEFLUC), CNRS and Universite’ Paris VII. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.