2146 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 7
Akgu¨n et al.
stromal tumours. Eur. J. Nucl. Med. Mol. Imaging 2004, 31, 803–
810.
(15) Behr, T. M.; Be´he´, M. P. Cholecystokinin-B/Gastrin receptor-targeting
peptides for staging and therapy of medullary thyroid cancer and other
cholecystokinin-B receptor-expressing malignancies. Semin. Nucl. Med.
2002, 32, 97–109.
(16) Garc´ıa-Lo´pez, M. T.; Gonza´lez-Mun˜iz, R.; Mart´ın-Mart´ınez, M.;
Herranz, R. Strategies for design of non peptide CCK1R agonist/
antagonist ligands. Curr. Top. Med. Chem. 2007, 7, 1180–1194.
(17) Berna, M. J.; Tapia, J. A.; Sancho, V.; Jensen, R. T. Progress in
developing cholecystokinin (CCK)/gastrin receptor ligands that have
therapeutic potential. Curr. Opin. Pharmacol. 2007, 7, 583–592.
(18) Chang, R. S.; Lotti, V. J. Biochemical and pharmacological
characterization of an extremely potent and selective nonpeptide
cholecystokinin antagonist. Proc. Natl. Acad. Sci. U.S.A 1986, 83,
4923–4926.
CCK-8 and gastrin, whereas the latter bind only CCK-8 with
high affinity. The slides were then exposed to a radiation-
sensitive film. The density of the CCK2 receptor-specific signal
on the film was quantified using a computer-assisted image
processing system (Interfocus, Mering, Germany) and radioactive
tissue standards (Autoradiographic [14C] microscales, GE Health-
care, Little Chalfont, UK) containing known amounts of isotope,
cross-calibrated to tissue-equivalent ligand concentrations.43,44
In Vitro Receptor Autoradiography for Compound 7 and
Compound 9 Binding Sites. For autoradiography studies, the
precursor compounds 6 and 8 were 125I-radioiodinated with the
chloramine T method and purified by reversed-phase (C-18) HPLC
(Anawa, Wangen, Switzerland). Specific activity was 2000 Ci/
mmol. Receptor autoradiography was performed as described above
for 125I-CCK. Displacement experiments were performed with
increasing concentrations of cold compounds 3, 5, 10, gastrin, and
CCK.
(19) Huang, S. C.; Fortune, K. P.; Wank, S. A.; Kopin, A. S.; Gardner,
J. D. Multiple affinity states of different cholecystokinin receptors.
J. Biol. Chem. 1994, 269, 26121–2616.
(20) Hadac, E. M.; Dawson, E. S.; Darrow, J. W.; Sugg, E. E.; Lybrand,
T. P.; Miller, L. J. Novel benzodiazepine photoaffinity probe stereo-
selectively labels a site deep within the membrane-spanning domain
of the cholecystokinin receptor. J. Med. Chem. 2006, 49, 850–863.
(21) Gao, F.; Sexton, P. M.; Christopoulos, A.; Miller, L. J. Benzodiazepine
ligands can act as allosteric modulators of the type 1 cholecystokinin
receptor. Bioorg. Med. Chem. Lett. 2008, 18, 4401–4404.
(22) Bock, M. G.; DiPardo, R. M.; Evans, B. E.; Rittle, K. E.; Whitter,
W. L.; Garsky, V. M.; Gilbert, K. F.; Leighton, J. L.; Carson, K. L.;
Mellin, E. C. Development of 1,4-benzodiazepine cholecystokinin type
B antagonists. J. Med. Chem. 1993, 36, 4276–4292.
Acknowledgment. We acknowledge the support of NIH
grants DK32878 (L.J.M.) and DA01591 (P.S.P.), fellowship no.
1267 from the Swiss Foundation for Medical-Biological Fel-
lowships and Novartis (M.K.), and grant no. 3200-105726 from
the Swiss National Science Foundation (J.C.R.). We acknowl-
edge the contributions by R. Date.
(23) Freidinger, R. M. Cholecystokinin and gastrin antagonists. Med. Res.
ReV. 1989, 9, 271–290.
(24) Bock, M. G.; DiPardo, R. M.; Evans, B. E.; Rittle, K. E.; Veber, D. F.;
Freidinger, R. M.; Hirshfield, J.; Sringer, J. P. Synthesis and Resolution
of 3-Amine-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-ones. J.
Org. Chem. 1987, 52, 3232–3239.
(25) Reider, P. J.; Davis, P.; Hughes, D. L.; Grabowski, E. J. J. Crystal-
lization-Induced Asymmetric Transformation: Stereospecific Synthesis
of a Potent Peripheral CCK Antagonist. J. Org. Chem. 1987, 52, 955–
957.
(26) Akgu¨n, E.; Zheng, Y.; Harikumar, K. G.; Hopson, J.; Miller, L. J.;
Portoghese, P. S. Induction of heterodimerization of mu opioid peptide
(MOP) and type-2 cholecystokinin (CCK2) receptor by novel bivalent
ligands. Drugs Future 2008, 33, 152.
(27) Harikumar, K. G.; Puri, V.; Singh, R. D.; Hanada, K.; Pagano, R. E.;
Miller, L. J. Differential effects of modification of membrane
cholesterol and sphingolipids on the conformation, function, and
trafficking of the G protein-coupled cholecystokinin receptor. J. Biol.
Chem. 2005, 280, 2176–2185.
(28) Reubi, J. C.; Waser, B.; La¨derach, U.; Stettler, C.; Friess, H.; Halter,
F.; Schmassmann, A. Localization of cholecystokinin A and chole-
cystokinin B-gastrin receptors in the human stomach. Gastroenterology
1997, 112, 1197–1205.
(29) Roettger, B. F.; Ghanekar, D.; Rao, R.; Toledo, C.; Yingling, J.; Pinon,
D.; Miller, L. J. Antagonist-stimulated internalization of the G protein-
coupled cholecystokinin receptor. Mol. Pharmacol. 1997, 51, 357–
362.
(30) McCarthy, K. E.; Woltering, E. A.; Anthony, L. B. In situ radiotherapy
with 111In-pentetreotide: state of the art and perspectives. Q. J. Nucl.
Med 2000, 44, 88–95.
References
(1) Reubi, J. C. Peptide receptors as molecular targets for cancer diagnosis
and therapy. Endocr. ReV. 2003, 24, 389–427.
(2) Khan, I. U.; Beck-Sickinger, A. G. Targeted tumor diagnosis and
therapy with peptide hormones as radiopharmaceuticals. Anticancer
Agents Med. Chem. 2008, 8, 186–199.
(3) Gibril, F.; Reynolds, J. C.; Doppman, J. L.; Chen, C. C.; Venzon,
D. J.; Termanini, B.; Weber, H. C.; Stewart, C. A.; Jensen, R. T.
Somatostatin receptor scintigraphy: its sensitivity compared with that
of other imaging methods in detecting primary and metastatic
gastrinomas. Ann. Intern. Med. 1996, 125, 26–34.
(4) Kwekkeboom, D. J.; Teunissen, J. J.; Bakker, W. H.; Kooij, P. P.; de
Herder, W. W.; Feelders, R. A.; van Eijck, C. H.; Esser, J. P.; Kam,
B. L.; Krenning, E. P. Radiolabeled somatostatin analog [177Lu-
DOTA0, Tyr3]octreotate in patients with endocrine gastroenteropan-
creatic tumors. J. Clin. Oncol. 2005, 23, 2754–2762.
(5) Ginj, M.; Zhang, H.; Waser, B.; Cescato, R.; Wild, D.; Wang, X.;
Erchegyi, J.; Rivier, J.; Macke, H. R.; Reubi, J. C. Radiolabeled
somatostatin receptor antagonists are preferable to agonists for in vivo
peptide receptor targeting of tumors. Proc. Natl. Acad. Sci. U.S.A 2006,
103, 16436–16441.
(6) Cescato, R.; Erchegyi, J.; Waser, B.; Piccand, V.; Maecke, H. R.;
Rivier, J. E.; Reubi, J. C. Design and in vitro characterization of highly
sst2-selective somatostatin antagonists suitable for radiotargeting.
J. Med. Chem. 2008, 51, 4030–4037.
(7) Cescato, R.; Maina, T.; Nock, B.; Nikolopoulou, A.; Charalambidis,
D.; Piccand, V.; Reubi, J. C. Bombesin receptor antagonists may be
preferable to agonists for tumor targeting. J. Nucl. Med. 2008, 49,
318–326.
(8) Perrin, M. H.; Sutton, S. W.; Cervini, L. A.; Rivier, J. E.; Vale, W. W.
Comparison of an agonist, urocortin, and an antagonist, astressin, as
radioligands for characterization of corticotropin-releasing factor
receptors. J. Pharmacol. Exp. Ther. 1999, 288, 729–734.
(9) Sleight, A. J.; Stam, N. J.; Mutel, V.; Vanderheyden, P. M. Radiola-
belling of the human 5-HT2A receptor with an agonist, a partial agonist
and an antagonist: effects on apparent agonist affinities. Biochem.
Pharmacol. 1996, 51, 71–76.
(10) Waelbroeck, M.; Robberecht, P.; Chatelain, P.; Christophe, J. Rat
cardiac muscarinic receptors. I. Effects of guanine nucleotides on high-
and low-affinity binding sites. Mol. Pharmacol. 1982, 21, 581–588.
(11) Talkad, V. D.; Fortune, K. P.; Pollo, D. A.; Shah, G. N.; Wank, S. A.;
Gardner, J. D. Direct demonstration of three different states of the
pancreatic cholecystokinin receptor. Proc. Natl. Acad. Sci. U.S.A 1994,
91, 1868–1872.
(12) Reubi, J. C. Targeting CCK receptors in human cancers. Curr. Top.
Med. Chem. 2007, 7, 1239–1242.
(13) Reubi, J. C.; Waser, B. Concomitant expression of several peptide
receptors in neuroendocrine tumours: molecular basis for in vivo
multireceptor tumour targeting. Eur. J. Nucl. Med. Mol. Imaging 2003,
30, 781–793.
(31) Chang, R. S.; Lotti, V. J.; Chen, T. B.; Kunkel, K. A. Characterization
of the binding of [3H]-(()-L-364,718: a new potent, nonpeptide
cholecystokinin antagonist radioligand selective for peripheral recep-
tors. Mol. Pharmacol. 1986, 30, 212–217.
(32) Silvente-Poirot, S.; Hadjiivanova, C.; Escrieut, C.; Dufresne, M.;
Martinez, J.; Vaysse, N.; Fourmy, D. Study of the states and
populations of the rat pancreatic cholecystokinin receptor using the
full peptide antagonist JMV 179. Eur. J. Biochem. 1993, 212, 529–
238.
(33) Knapp, R. J.; Vaughn, L. K.; Fang, S. N.; Bogert, C. L.; Yamamura,
M. S.; Hruby, V. J.; Yamamura, H. I. A new, highly selective CCK-B
receptor radioligand ([3H][N-methyl-Nle28,31]CCK26-33): evidence for
CCK-B receptor heterogeneity. J. Pharmacol. Exp. Ther. 1990, 255,
1278–1286.
(34) Haradahira, T.; Inoue, O.; Kobayashi, K.; Suzuki, K. Synthesis and
evaluation of 11C-labeled nonpeptide antagonists for cholecystokinin
receptors: [11C]L-365,260 and [11C]L-365,346. Nucl. Med. Biol. 1998,
25, 203–208.
(35) Behr, T. M.; Gotthardt, M.; Becker, W.; Be´he´, M. Radioiodination of
monoclonal antibodies, proteins and peptides for diagnosis and therapy.
A review of standardized, reliable and safe procedures for clinical
grade levels kBq to GBq in the Go¨ttingen/Marburg experience.
Nuklearmedizin 2002, 41, 71–79.
(14) Reubi, J. C.; Ko¨rner, M.; Waser, B.; Mazzucchelli, L.; Guillou, L.
High expression of peptide receptors as a novel target in gastrointestinal