Increase in peripheral benzodiazepine binding sites in colonic adenocarcinoma

Binding characteristics of peripheral benzodiazepine binding sites (PBS) in membrane homogenates of samples taken at abdominal surgery from colonic adenocarcinoma and from healthy colonic tissues in 17 patients were determined. [3H]PK 11195, an isoquinoline carboxamide derivative, which exhibits high affinity to PBS, was used as a radioligand for the binding assay. A robust increase (3.1-fold) was found in membranes from the tumor sites as compared to normal control colon, whereas the affinity of [3H]PK 11195 to PBS was similar in both tissues.