Down-regulation of <i>Epidermal Growth Factor Receptor</i> by Selective Expansion of a 5′-End Regulatory Dinucleotide Repeat in Colon Cancer with Microsatellite Instability

Abstract

The EGFR(CA)n elongation observed in tumors cannot be explained by an intrinsic property of this repeat favoring insertions versus deletions. Instead, a selection for repeat elongation occurs in microsatellite instability-positive tumors, leading to EGFR down-regulation. These findings suggest that in microsatellite instability-positive tumors current therapies targeting EGFR overexpression may have either no effect or an opposite to the expected effect.