LOCAL UP-REGULATION OF NEUROPEPTIDE RECEPTORS IN HOST BLOOD-VESSELS AROUND HUMAN COLORECTAL CANCERS

Background & Aims: Neuropeptide receptors, expressed at high density b y neoplastic cells, can be instrumental for diagnosis and therapy, How ever, little is known about neuropeptides and neuropeptide receptors i n the tumor bed, The aim of this study was to study the expression of two neuropeptide receptors in peritumoral blood vessels, Methods: Soma tostatin and substance P receptors were measured using in vitro recept or autoradiography in well-defined submucosal and subserosal vessels l ocated in the immediate surroundings of human colorectal carcinomas or in normal colon taken at increasing distances from the tumor, Results : Both receptors were 3-5-fold overexpressed in the host veins within a 2-cm-wide area surrounding human primary colorectal carcinomas compa red with veins located at 5-10-cm distance in normal gut tissue, The e xpression of peritumoral vascular somatostatin receptor and substance P receptor appears independent of receptor expression in the tumor, of tumor stage, and of the grade of local inflammation. Conclusions: The se biochemical alterations of veins in the immediate vicinity of tumor s represent a novel tumor-related site of expression for the two recep tors and may point to a new biological principle of host-tumor interac tion. Thus, vascular regulatory mechanisms in the tumor bed may be imp ortant for tumor development and metastasis and may be used as a targe t for tumor therapy.