EGF-IGF-1 signal cross-talk: ERK regulates Irs-1 transcription

Introduction: We observed that ursodeoxycholic acid (UDCA), whose potential as a chemopreventive agent is under investigation, inhibits proliferation of colonic epithelial cells. We investigated the effect of UDCA on EGF and IGF-1 signals, both of which regulate proliferation. Since a cross-talk between the IGF-1 and EGF pathways has been shown, we investigated also the effect of UDCA on the interaction of both pathways. Materials and methods: IEC-6 cells were treated with increasing concentrations of UDCA in the presence or absence of 1 nM EGF or 10 nM IGF-1. ERK-phosphorylation and Irs-1 protein expression wer…