title: High expression of gastrin-releasing peptide receptors in the vascular bed of urinary tract cancers: promising candidates for vascular targeting applications.
abstract: Tumoral gastrin-releasing peptide (GRP) receptors are potential targets for diagnosis and therapy using radiolabeled or cytotoxic GRP analogs. GRP-receptor overexpression has been detected in endocrine-related cancer cells and, more recently, also in the vascular bed of selected tumors. More information on vascular GRP-receptors in cancer is required to asses their potential for vascular targeting applications. Therefore, frequent human cancers (n = 368) were analyzed using in vitro GRP-receptor autoradiography on tissue sections with the (125)I-[Tyr(4)]-bombesin radioligand and/or the universal radioligand (125)I-[d-Tyr(6), beta-Ala(11), Phe(13), Nle(14)]-bombesin(6-14). GRP-receptor expressing vessels were evaluated in each tumor group for prevalence, quantity (vascular score), and GRP-receptor density. Prevalence of vascular GRP-receptors was variable, ranging from 12% (prostate cancer) to 92% (urinary tract cancer). Different tumor types within a given site had divergent prevalence of vascular GRP-receptors (e.g. lung: small cell cancer: 0%; adenocarcinoma: 59%; squamous carcinoma: 83%). Also the vascular score varied widely, with the highest score in urinary tract cancer (1.69), moderate scores in lung (0.91), colon (0.88), kidney (0.84), and biliary tract (0.69) cancers and low scores in breast (0.39) and prostate (0.14) cancers. Vascular GRP-receptors were expressed in the muscular vessel wall in moderate to high densities. Normal non-neoplastic control tissues from these organs lacked vascular GRP-receptors. In conclusion, tumoral vessels in all evaluated sites express GRP-receptors, suggesting a major biological function of GRP-receptors in neovasculature. Vascular GRP-receptor expression varies between the tumor types indicating tumor-specific mechanisms in their regulation. Urinary tract cancers express vascular GRP-receptors so abundantly, that they are promising candidates for vascular targeting applications.
authors.affiliation: Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Bern, CH-3010 Bern, Switzerland.
authors.forename: Achim
authors.initials: A
authors.lastname: Fleischmann
authors.forename: Beatrice
authors.initials: B
authors.lastname: Waser
authors.forename: Jean Claude
authors.initials: JC
authors.lastname: Reubi
mesh_terms: D001345:Autoradiography; D001839:Bombesin / Q000378:metabolism; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D011379:Prognosis; D018004:Receptors, Bombesin / Q000378:metabolism*; D014571:Urologic Neoplasms / Q000098:blood supply* / Q000378:metabolism* / Q000473:pathology
chemical_list: D007457:Iodine Radioisotopes; D018004:Receptors, Bombesin; D001839:Bombesin