The Insulin-like Growth Factor 1
Receptor (IGF-1R) is a transmembrane receptor that is activated by Insulin-like
Growth Factor (IGF-1) and by the related growth factor IGF-2. It belongs to the
large class of tyrosine kinase receptors. IGF-1 stimulates mitosis and inhibits
apoptosis thus enhancing cell survival. The IGF-1 receptor is expressed in all
cell types and tissues and is highly over-expressed in most malignant tissues.
IGF-1 has been shown to induce hypoxia-inducible factor-1 (HIF-1) mediated
vascular endothelial growth factor (VEGF) expression. Other studies have shown
IGF-1 to be a possible predictive factor for resistance to treatment with
anti-EGFR monoclonal antibodies in K-RAS wild type colorectal cancer. Combined
IGF-1 and K-RAS analysis may represent an effective strategy for a better
selection of responding colorectal cancer
patients.