The WT1 Wilms' tumor suppressor gene product interacts with estrogen receptor-alpha and regulates IGF-I receptor gene transcription in breast cancer cells.
An important transcriptional regulatory factor that appears to be responsible for controlling IGF-I receptor gene expression is the product of the WT1 Wilms tumor suppressor gene.
The levels of endogenous IGF-I-R mRNA and the activity of IGF-I-R gene promoter fragments in luciferase reporter constructs were found to be significantly higher in G401 cells (a Wilms' tumor-derived cell line lacking detectable WT1 mRNA) than in 293 cells (a human embryonic kidney cell line which expresses significant levels of WT1 mRNA).
IGF-IR gene (designated IGF1R) expression in the tumors was inversely correlated with the expression of the Wilms tumor suppressor gene WT1, whose inactivation appears to be a key step in the etiology of Wilms tumor.