Peptide hormones of the
glucagon-like peptide (GLP) family play an increasing clinical role, such as
GLP-1 in diabetes
therapy. Moreover, GLP receptors are overexpressed in various human
tumor types and therefore represent molecular targets for important clinical applications. In particular, virtually all benign
insulinomas highly overexpress
GLP-1 receptors (GLP-1R). Targeting GLP-1R with the stable
GLP-1 analogs (111)In-
DOTA/DPTA-
exendin-4 offers a new approach to successfully localize these small
tumors. This non-invasive technique has the potential to replace the invasive localization of
insulinomas by selective arterial stimulation and venous sampling. Malignant
insulinomas, in contrast to their benign counterparts, express GLP-1R in only one-third of the cases, while they more often express the
somatostatin type 2 receptors. Importantly, one of the two receptors appears to be always expressed in malignant
insulinomas. The GLP-1R overexpression in selected
cancers is worth to be kept in mind with regard to the increasing use of
GLP-1 analogs for diabetes
therapy. While the functional role of GLP-1R in
neoplasia is not known yet, it may be safe to monitor patients undergoing
GLP-1 therapy carefully.