Embryonic stem cell factor FOXD3 (Genesis) defects in gastrointestinal stromal tumors

Area of Science:

• Oncology
• Developmental Biology
• Gastroenterology

Background:

• Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms originating from interstitial cells of Cajal (ICC).
• GIST pathogenesis is often linked to tyrosine kinase receptor (TKR) KIT or PDGFRA overexpression.
• The embryonic stem cell factor FOXD3 plays a role in gastrointestinal and neural crest cell development.

Purpose of the Study:

• To investigate the role of FOXD3 in GIST pathogenesis.
• To identify genetic variants of FOXD3 associated with GIST.
• To elucidate the functional link between FOXD3, ICC, and KIT in GIST development.

Main Methods:

• Molecular analyses of 58 wild-type GIST patient samples (Sanger sequencing, CGH, methylation analysis).
• Immunohistochemistry and Western blot to assess FOXD3 expression.
• In vitro functional studies in tissue and transfected cells, plus zebrafish and mouse models of FOXD3 deficiency.

Main Results:

• Germline partially inactivating FOXD3 variants (p.R54H, p.Ala88_Gly91del) identified in GIST patients.
• Chromosome 1p loss was the most frequent abnormality in GISTs.
• FOXD3 variants impaired its function; FOXD3 deficiency disrupted GI neural networks and altered ICC in animal models.

Conclusions:

• FOXD3 defects are linked to GIST formation.
• FOXD3 inactivation leads to increased ICC and KIT overexpression.
• FOXD3 acts as a suppressor of KIT expression, highlighting its role in GIST pathogenesis.