ITF-2, a downstream target of the Wnt/TCF pathway, is activated in human cancers with β-catenin defects and promotes neoplastic transformation

In many cancers, inactivation of the adenomatous polyposis coli (APC) or Axin tumor suppressor proteins or activating mutations in β-catenin lead to elevated β-catenin levels, enhanced binding of β-catenin to T cell factor (TCF) proteins, and increased expression of TCF-regulated genes. We found that the gene for the basic helix-loop-helix transcription factor ITF-2 (immunoglobulin transcription factor-2) was activated in rat E1A-immortalized RK3E cells following neoplastic transformation by β-catenin or ligand-induced activation of a β-catenin-estrogen receptor fusion protein. Human cancers with β-catenin regulatory defects had elevated ITF-2 expression, and ITF-2 was repressed by restoring wild-type APC function or inhibiting TCF activity. Of note, ITF-2 promoted neoplastic transformation of RK3E cells. We propose that ITF-2 is a TCF-regulated gene, which functions in concert with other TCF target genes to promote growth and/or survival of cancer cells with defects in β-catenin regulation.