title: Design, synthesis, and biological evaluation of an antagonist-bombesin analogue as targeting vector.
abstract: The gastrin releasing peptide receptor (GRP-R) is overexpressed on a number of tumors and cancer cell lines including pancreas, prostate, breast, gastrointestinal, and small cell lung cancer (SCLC). Radiolabeled bombesin (BBN) analogues have exhibited high binding affinity and specificity to the GRP-R. A bombesin analogue with an antagonist targeting vector at the C-terminus, DOTA-aminohexanoyl-[D-Phe(6), Leu-NHCH 2CH 2CH3(13), des Met(14)] BBN[6-14] (1, "Bomproamide"), has been synthesized and displays high binding affinity (IC50 = 1.36 +/- 0.09 nM) against (125)I-Tyr (4)-BBN in in vitro competitive assays using PC-3 cells. Maximum internalization of (111)In-1 reached 14% in PC-3 cells after 45 min of incubation. Rapid (0.25 h PI) and high (12.21 +/- 3.2%ID/g) pancreatic uptake of (111)In-1 was observed in healthy CF-1 mice, and 90% of the activity was blocked by coinjection of 100 mug of BBN. Rapid (0.25 h PI) and high uptake (6.90 +/- 1.06%ID/g) was observed in PC-3 prostate cancer xenografts in SCID mice, as well as visualized clearly in a SPECT/CT study. These results support the use of a bombesin construct with an antagonist C-terminal vector as a candidate of choice for specific in vivo imaging of tumors overexpressing GRP-receptors.
authors.affiliation: Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA. levers@missouri.edu.
authors.forename: Wael R
authors.initials: WR
authors.lastname: Abd-Elgaliel
authors.forename: Fabio
authors.initials: F
authors.lastname: Gallazzi
authors.forename: Jered C
authors.initials: JC
authors.lastname: Garrison
authors.forename: Tammy L
authors.initials: TL
authors.lastname: Rold
authors.forename: Gary L
authors.initials: GL
authors.lastname: Sieckman
authors.forename: Said Daibes
authors.initials: SD
authors.lastname: Figueroa
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Hoffman
authors.forename: Susan Z
authors.initials: SZ
authors.lastname: Lever
mesh_terms: D000818:Animals; D001839:Bombesin / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002614:Chelating Agents / Q000737:chemistry; D015195:Drug Design; D015870:Gene Expression; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry; D006801:Humans; D007205:Indium Radioisotopes; D020128:Inhibitory Concentration 50; D008297:Male; D051379:Mice; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000493:pharmacokinetics / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism; D018004:Receptors, Bombesin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013194:Staining and Labeling; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
chemical_list: D002614:Chelating Agents; D006573:Heterocyclic Compounds, 1-Ring; D007205:Indium Radioisotopes; D009942:Organometallic Compounds; D018004:Receptors, Bombesin; C533687:bomproamide; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; D001839:Bombesin