CCK-B Receptor Research Articles

Cholecystokinin receptor antagonist halts progression of pancreatic cancer precursor lesions and fibrosis in mice.

Exogenous administration of cholecystokinin (CCK) induces hypertrophy and hyperplasia of the pancreas with an increase in DNA content. We hypothesized that endogenous CCK is involved in the malignant progression of pancreatic intraepithelial neoplasia (PanIN) lesions and the fibrosis associated with pancreatic cancer. The presence of CCK receptors in early PanIN lesions was examined by immunohistochemistry in mouse and human pancreas. Pdx1-Cre/LSL-Kras transgenic mice were randomized to receive either untreated drinking water or water supplemented with a CCK receptor antagonist (proglumide, 0.1 mg/mL). Pancreas from the mice were removed and examined histologically for number and grade of PanINs after 1, 2, or 4 months of antagonist therapy. Both CCK-A and CCK-B receptors were identified in early stage PanINs from mouse and human pancreas. The grade of PanIN lesions was reversed, and progression to advanced lesions arrested in mice treated with proglumide compared with the controls (P = 0.004). Furthermore, pancreatic fibrosis was significantly reduced in antagonist-treated animals compared with vehicle (P < 0.001). These findings demonstrate that endogenous CCK is in part responsible for the development and progression of pancreatic cancer. The use of CCK receptor antagonists may have a role in cancer prophylaxis in high-risk subjects and may reduce fibrosis in the microenvironment.

Abstract 2125: G-protein coupled receptors for cholecystokinin regulate transactivation of EGF receptors in lung cancer cells

Abstract Cholecystokinin (CCK) receptors (CCK-AR and CCK-BR) are G-protein coupled receptors (GPCR) which are present on lung cancer cells (Yoder and Moody, Peptides 1987; 8: 103). CCK stimulates the proliferation of NCI-H345 cells, whereas the CCK-B receptor antagonist CI-988 inhibits proliferation (Moody et al., JPET 2001; 299: 1154). Peptide receptors for some gastrointestinal hormones/neurotransmitters mediate lung cancer growth by causing EGFR transactivation, but it is unknown if this occurs with CCK-BR. CCK-BR mRNA was detected in NCI-H345 and H727 lung cancer cells. Addition of CCK-8 or gastrin I (100 nM) to NCI-H345 or H727 cells, which have wild type EGFR, increased EGFR Tyr1068 phosphorylation after 5 min. The ability of CCK-8 to cause EGFR or ERK tyrosine phosphorylation was blocked by CI-988 (CCK-BR antagonist), gefitinib (EGFR tyrosine kinase inhibitor), PP2 (Src inhibitor), GM6001 (matrix metalloprotease inhibitor), tiron (superoxide scavenger) and U-73122 (phospholipase C inhibitor) but not H89 (protein kinase A inhibitor). U-73122 or CI-988 inhibited the ability of CCK to cause phosphatidylinositol turnover and elevate cytosolic Ca2+. CI-988 or gefitinib inhibited the growth of NCI-H345 or H727 cells. CI-988 and gefitinib synergistically inhibited the growth of lung cancer cells. The results indicate that the CCK-BR regulates lung cancer proliferation in an EGFR-dependent mechanism through activation of Src, MMP and reactive oxygen species. Citation Format: Terry W. Moody, Suk Hee Lee, Paola Moreno Perez, Robert T Jensen. G-protein coupled receptors for cholecystokinin regulate transactivation of EGF receptors in lung cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2125. doi:10.1158/1538-7445.AM2014-2125

Interaction between the cholecystokinin and endogenous cannabinoid systems in cued fear expression and extinction retention.

Post-traumatic stress disorder (PTSD) is thought to develop, in part, from improper inhibition of fear. Accordingly, one of the most effective treatment strategies for PTSD is exposure-based psychotherapy. Ideally, neuroscience would inform adjunct therapies that target the neurotransmitter systems involved in extinction processes. Separate studies have implicated the cholecystokinin (CCK) and endocannabinoid systems in fear; however, there is a high degree of anatomical colocalization between the cannabinoid 1 receptor (Cnr1) and CCK in the basolateral amygdala (BLA), a brain region critical for emotion regulation. Although most research has focused on GABA and GABAergic plasticity as the mechanism by which Cnr1 mediates fear inhibition, we hypothesize that a functional interaction between Cnr1 and CCKB receptor (CCKBR) is critical for fear extinction processes. In this study, systemic pharmacological manipulation of the cannabinoid system modulated cued fear expression in C57BL/6J mice after consolidation of auditory fear conditioning. Knockout of the CCKBR, however, had no effect on fear- or anxiety-like behaviors. Nonetheless, administration of a Cnr1 antagonist increased freezing behavior during a cued fear expression test in wild-type subjects, but had no effect on freezing behavior in CCKBR knockout littermates. In addition, we found that Cnr1-positive fibers form perisomatic clusters around CCKBR-positive cell bodies in the BLA. These CCKBR-positive cells comprise a molecularly heterogenous population of excitatory and inhibitory neurons. These findings provide novel evidence that Cnr1 contributes to cued fear expression via an interaction with the CCK system. Dysfunctional Cnr1-CCKBR interactions might contribute to the etiology of, or result from, fear-related psychiatric disease.

CCK-B receptor variant as a potential prognostic factor in pancreatic adenocarcinoma

CCK-B receptor variant as a potential prognostic factor in pancreatic adenocarcinoma

Investigation of cholecystokinin receptors in the human lower esophageal sphincter.

To compare the binding of cholecystokinin (CCK)-8 to CCK receptors in sling and clasp fibers of the human lower esophageal sphincter. Esophageal sling and clasp fibers were isolated from eight esophagectomy specimens, resected for squamous cell carcinoma in the upper two thirds of the esophagus, which had been maintained in oxygenated Kreb's solution. Western blot was used to measure CCK-A and CCK-B receptor subtypes in the two muscles. A radioligand binding assay was used to determine the binding parameters of (3)H-CCK-8S to the CCK receptor subtypes. The specificity of binding was determined by the addition of proglumide, which blocks the binding of CCK to both receptor subtypes. There was no significant difference between the sling and clasp fibers of the human lower esophageal sphincter in the amount of CCK-A [integrated optical density (IOD) value: 22.65 ± 0.642 vs 22.328 ± 1.042, P = 0.806] or CCK-B receptor protein (IOD value: 13.20 ± 0.423 vs 12.45 ± 0.294, P = 0.224) as measured by Western blot. The maximum binding of radio-labeled CCK-8S was higher in the sling fibers than in the clasp fibers (595.75 ± 3.231 cpm vs 500.000 ± 10.087 cpm, P < 0.001) and dissociation constant was lower (K(d): 1.437 ± 0.024 nmol/L vs 1.671 ± 0.024 nmol/L, P < 0.001). The IC₅₀ of the receptor specific antagonists were lower for the CCK-A receptors than for the CCK-B (P < 0.01). CCK binding modulates the contractile function of the lower esophageal sphincter through differential binding to the CCK-A receptor on the sling and clasp fibers.

Synthesis, Analytical Analysis, and Medicinal Aspect of Novel Benzimidazoles and their Metal Complexes

Benzimidazole and their metal analogs that can act as multimodal agent and have non-peptidic CCK-B receptor antagonist were synthesized and characterized on the basis of spectroscopic techniques such as FT-IR, NMR, FAB-MS and also evaluated for biologic efficacy. The ligands showed binding to most of the organs, known to express CCK receptors in biodistribution studies. Cholecystokinin (CCK1 and CCK2) receptor binding affinities of these analogs (IC50) are 0.802 ± 0.007 for compound C and 0.326 ± 0.012 for compound D in rat pancreatic acini. These studies have provided a new template for further development of novel agents for various related diseases.

Cholecystokinin: An Excitatory Modulator of Mitral/Tufted Cells in the Mouse Olfactory Bulb

Cholecystokinin (CCK) is widely distributed in the brain as a sulfated octapeptide (CCK-8S). In the olfactory bulb, CCK-8S is concentrated in two laminae: an infraglomerular band in the external plexiform layer, and an inframitral band in the internal plexiform layer (IPL), corresponding to somata and terminals of superficial tufted cells with intrabulbar projections linking duplicate glomerular maps of olfactory receptors. The physiological role of CCK in this circuit is unknown. We made patch clamp recordings of CCK effects on mitral cell spike activity in mouse olfactory bulb slices, and applied immunohistochemistry to localize CCKB receptors. In cell-attached recordings, mitral cells responded to 300 nM –1 µM CCK-8S by spike excitation, suppression, or mixed excitation-suppression. Antagonists of GABAA and ionotropic glutamate receptors blocked suppression, but excitation persisted. Whole-cell recordings revealed that excitation was mediated by a slow inward current, and suppression by spike inactivation or inhibitory synaptic input. Similar responses were elicited by the CCKB receptor-selective agonist CCK-4 (1 µM). Excitation was less frequent but still occurred when CCKB receptors were blocked by LY225910, or disrupted in CCKB knockout mice, and was also observed in CCKA knockouts. CCKB receptor immunoreactivity was detected on mitral and superficial tufted cells, colocalized with Tbx21, and was absent from granule cells and the IPL. Our data indicate that CCK excites mitral cells postsynaptically, via both CCKA and CCKB receptors. We hypothesize that extrasynaptic CCK released from tufted cell terminals in the IPL may diffuse to and directly excite mitral cell bodies, creating a positive feedback loop that can amplify output from pairs of glomeruli receiving sensory inputs encoded by the same olfactory receptor. Dynamic plasticity of intrabulbar projections suggests that this could be an experience-dependent amplification mechanism for tuning and optimizing olfactory bulb signal processing in different odor environments.

Tu1923 A Single Nucleotide Polymorphism of the CCK-B Receptor Does Not Effect Survival in Colon & Gastric Cancer

Tu1923 A Single Nucleotide Polymorphism of the CCK-B Receptor Does Not Effect Survival in Colon & Gastric Cancer

The CCKB antagonist CI988 reduces food intake in fasted rats via a dopamine mediated pathway

Studies have shown a reduction of food intake following peripheral and brain injection of CCK. However, it remains to be established whether endogenous central CCK is involved in the regulation of food intake. We investigated the role of central CCK in the regulation of food intake by pharmacological manipulation of the CCKB (CCK2) receptor system. Intracerebroventricularly (ICV) cannulated male Sprague Dawley rats were fasted for 24h and received an ICV injection of the CCKB receptor antagonist CI988 at a dose of 10nmol or 49nmol or vehicle. Another group received two consecutive ICV injections consisting of the corticotropin-releasing factor (CRF) receptor-1 (CRF1) antagonist, CP376395 (3nmol) or the CRF2 receptor antagonist, K41498 (2nmol) alone, or followed by CI988 (49nmol). Lastly, another group of rats received an intraperitoneal (IP) injection of the dopamine antagonist, flupentixol (∼197 and ∼493nmol/kg) alone, or followed by CI988 (49nmol, ICV). Cumulative food intake was assessed for 11h. Vehicle injected rats showed a robust feeding response. CI988 at 49nmol reduced food intake by 30% starting at 2h post injection. CP376395 and K41498 had no effect on food intake. Flupentixol injected IP at a dose of 197 and 493nmol/kg alone did not modulate food intake whereas the higher dose blocked the CI988-induced reduction of feeding. During the dark phase, CI988 had no effect on food intake in unfasted rats. In summary, CCKB signaling is involved in the regulation of food intake after a fast likely by downstream dopamine signaling.

Behavioral and cortical EEG evaluations confirm the roles of both CCKA and CCKB receptors in mouse CCK-induced anxiety

This study investigated the roles of cholecystokinin (CCK)A and CCKB receptors on CCK-4-induced anxiety-like behaviors in mice through behavioral and neural evaluations. Anxiety-like behaviors in mice were induced by an intracerebroventricular (i.c.v.) administration of CCK-4, which can bind to both CCKA and CCKB receptors. The effects of CCKA and CCKB receptor antagonists (devazepide and CI-988, respectively) were examined using mouse anxiety tests (elevated-plus maze and light–dark box) and also by examining neuronal activities through EEG monitoring and c-Fos immunohistochemistry in the cortex and amygdala. CCK-4 (3μg/kg of body weight i.c.v.) significantly induced mouse anxiety-like behaviors in the anxiety tests and also affected their EEG patterns with respect to pre-drug tracing, resulting in increase in spectral power in relative power distribution in the delta and theta bands (0.5–5Hz frequency bands) and also in increase in c-Fos immunopositive neuron counts. These CCK-4 effects were completely suppressed by 1.0mg/kg CCKB receptor antagonist, CI-988, while the same amount of CCKA receptor antagonist, devazepide was partly able to suppress the same effects. These findings indicated that not only CCKB receptors but also CCKA receptors in the brain play important roles in regulating anxiety-like behaviors in mice. The present study also proposed a possibility that cortical EEG is useful for assessing anxiety.

Modulation of acetylcholine release by cholecystokinin in striatum – receptor specificity; role of dopaminergic neuronal activity

Cholecystokinin, a neuroactive peptide functioning as a neurotransmitter and neuromodulator in the central nervous system, mediates a number of processes and is implicated in neurological and psychiatric disorders such as Parkinson's disease, anxiety and schizophrenia. Striatum is one of the brain structures with the highest concentrations of CCK in the brain, rich in CCK receptors as well. The physiological effect of CCK on cholinergic interneurons, which are the major interneurons in striatum and the modulatory interactions which exist between dopamine, acetylcholine and cholecystokinin in this brain structure are still unclear. We studied the effect of cholecystokinin octapeptide (CCK-8) on the release of acetylcholine (ACh) from striatal slices of the rat brain. CCK-8 (0.01-0.1μM) showed no statistically significant effect on the basal but enhanced dose-dependently the electrically (2Hz)-evoked release of [(3)H]ACh. When slices were preperfused with 100μM sulpiride, a selective dopamine D(2) receptor antagonist, the CCK-8 (0.01μM) effect on electrically stimulated ACh release was increased nearly 2-fold. A similar increase was observed after depletion of endogenous dopamine (DA) from nigro-striatal dopaminergic neurons with 6-hydroxydopamine (6-OHDA) (2× 250μg/animal, i.c.v.). Furthermore in the presence of dopamine (100μM) or apomorphine (10μM), the prototypical DA receptor agonist, CCK-8 (0.01μM) failed to enhance the stimulation-evoked release of [(3)H]ACh. The D(2) receptor agonist quinpirol (1μM) abolished the CCK-8 effect on electrically stimulated ACh release as well. The increase in electrically induced [(3)H]ACh release produced by 0.01μM CCK-8 was antagonized by d,l loxiglumide (CR 1505), 10μM, a non-peptide CCK-A receptor antagonist and by Suc-Tyr-(OSO3)-Met-Gly-Trp-Met-Asp-β-phenethyl-amide (GE-410), 1μM, a peptide CCK-A receptor antagonist. The antagonistic effect of GE-410 on the CCK-8-potentiated, electrically induced release of [(3)H]ACh was studied in striatum for the first time. CAM 1028 (10μM), a CCK-B receptor antagonist, also prevented the potentiating effect of CCK-8 (0.01μM) on electrically stimulated release of [(3)H]ACh. The presented results indicate that (i) CCK-8 is capable of increasing ACh elicited by field electrical stimulation in striatum; (ii) CCK-8 is more effective in its ACh-stimulating effect when dopaminergic activity in striatum is blocked i.e. CCK-8-facilitated release of electrically induced ACh from cholinergic interneurons in the striatum is under the inhibitory control of the tonic activity of dopamine from the nigrostriatal pathway; (iii) the enhancing effect of CCK-8 on electrically evoked ACh release is mediated through both CCK-A and CCK-B cholecystokinin receptors located most likely on the cell bodies of cholinergic interneurons in striatum.

Commentary: netazepide for gastric acid suppression – another kid on the block?

Just when it seemed all over, the manuscript by Boyce et al.1 examining the pharmacokinetics and pharmacodynamics of single dose administration of netazepide, a peripheral CCK-B (gastrin) receptor antagonist, in normal volunteers will most certainly reinvigorate interest in gastric acid secretion and its pharmacological inhibition. Netazepide appears to be a potent inhibitor of gastric acid secretion with rapid onset and a prolonged duration of action.1 If it can be shown to be both safe and effective as maintenance therapy, it may well give proton pump inhibitors (PPIs) a real run for their money. The PPIs, which irreversibly block the final common path of gastric acid production,2 have been the dominant class of antisecretory drugs for over two decades and their continuing supremacy was all but assured with the demise of the potassium competitive acid blockers (PCABs) (although there may be a comeback for this class of agents too3). In addition, concerns have surfaced recently about potential adverse effects from prolonged PPI use4 which has opened the door to other novel compounds such as netazepide. Of course, much work remains to be done with this agent and there are, as yet, many unanswered questions (some of which the authors may well address in two upcoming manuscripts concerning repetitive dosing of netazepide). For example, will tachyphylaxis develop after repeated administration of this competitive receptor antagonist, a phenomenon that has been well described with histamine H2 receptor antagonists, which act one step further along the gastric acid secretory pathway?5 In addition, the endocrine, neurocrine and paracrine networks that control gastric acid secretion and its feedback are redundant.6 It remains to be seen whether upregulation of other pathways could occur leading to additional loss of efficacy (tolerance) with time. Alternatively, will the drug, which appears to have a long secondary half-life, accumulate after repeated dosing leading to unexpected side effects? Moreover, little is known about the metabolism of this agent which has only been administered to a small cadre of normal volunteers. Will the effect of this agent be predictable in patients or will alterations in metabolism lead to ‘slow’ and ‘fast’ metabolisers and unpredictable antisecretory effects? Finally, will potent ECL-cell inhibition by netazepide lead to G-cell hyperplasia and hypergastrinaemia, with the potential for rebound ECL-cell histamine release and excessive gastric acid production4 on withdrawal of the drug? This possibility is of some interest given current concerns regarding rebound gastric acid hypersecretion in double-blind randomised trials of PPI use vs. placebo in normal volunteers.7, 8 On the other hand, judicious use of netazepide in concert with PPIs may lead to more precise titration of individual antisecretory effects, thereby mitigating ECL-cell hyperplasia and parietal cell hypertrophy. This is an exciting and provocative first-in-human study of a novel compound with significant potential. I fully agree with the authors' conclusions that ‘studies of repeated doses of netazepide are justified’.1 Declaration of personal interests: David Metz has served as a consultant and advisory board member for Novartis, as a consultant for AstraZeneca and Takeda, and has received research funding from Fercica. Declaration of funding interests: None

Downregulation of the CCK-B receptor in pancreatic cancer cells blocks proliferation and promotes apoptosis

Gastrin stimulates the growth of pancreatic cancer cells through the activation of the cholecystokinin-B receptor (CCK-BR), which has been found to be overexpressed in pancreatic cancer. In this study, we proposed that the CCK-BR drives growth of pancreatic cancer; hence, interruption of CCK-BR activity could potentially be an ideal target for cancer therapeutics. The effect of CCK-BR downregulation in the human pancreatic adenocarcinoma cells was examined by utilizing specific CCK-BR-targeted RNA interference reagents. The CCK-BR receptor expression was both transiently and stably downregulated by transfection with selective CCK-BR small-interfering RNA or short-hairpin RNA, respectively, and the effects on cell growth and apoptosis were assessed. CCK-BR downregulation resulted in reduced cancer cell proliferation, decreased DNA synthesis, and cell cycle arrest as demonstrated by an inhibition of G(1) to S phase progression. Furthermore, CCK-BR downregulation increased caspase-3 activity, TUNEL-positive cells, and decreased X-linked inhibitor of apoptosis protein expression, suggesting apoptotic activity. Pancreatic cancer cell mobility was decreased when the CCK-BR was downregulated, as assessed by a migration assay. These results show the importance of the CCK-BR in regulation of growth and apoptosis in pancreatic cancer. Strategies to decrease the CCK-BR expression and activity may be beneficial for the development of new methods to improve the treatment for patients with pancreatic cancer.

CCK-B receptor gene and response to cholecystokinin-tetrapeptide in healthy volunteers

Recent investigations suggest that genes that confer risk for panic disorder (PD) may moderate response to panicogenic agents in healthy volunteers. Given the potential role of the central cholecystokinin receptor (CCKBR) (CT) polymorphism alleles 26 and 27 in PD, the present study attempted to discern if these alleles moderated panicogenic sensitivity to the CCKBR agonist, CCK-tetrapeptide (CCK-4), in healthy volunteers. The study group consisted of 92 men and women with no personal or family history of psychiatric illness. Participants provided blood samples for genotyping of the CCKBR alleles and they received a 25μg bolus injection of CCK-4. Behavioral, cardiovascular and hormonal responses to the peptide were assessed and analyzed with adjusted linear regression models. Carriers of the CCKBR alleles tended to have higher levels of pre-challenge anxiety and significantly higher levels of anxiety sensitivity and introversion than those without the alleles. However, they did not exhibit an enhanced panicogenic response to CCK-4. Overall, our findings do not demonstrate a role of these alleles in modulating CCK-4's panicogenicity. The significant association between the risk alleles and anxiety-related personality traits is intriguing and further exploration of this association is merited.

Synthesis and Evaluation of N-(5-Methyl-3-oxo-1,2-diphenyl-2,3-dihydro-1H-pyrazol-4-yl)-N’-phenylureas as Cholecystokinin Antagonists

In the search for new cholecystokinin (CCK) ligands, ureidopyrazolines were identified in combinatorial libraries using 168 chemically diverse amines. The structure-activity relationship optimisation of this pyrazoline template 4a resulted in novel 3-oxo-1,2-diphenyl-2,3-di-hydro-1H-pyrazol-4-yl)-N'-phenylureas 5a-5o. These novel CCK ligands have shown to act as mixed CCK-A/CCK-B ligands in a [125]I-CCK-8 receptor binding assay. The best pyrazoline 5e of this series displayed an IC50 of 20 and 25 nmol/L for the CCK-A, and CCK-B receptor, respectively. In a subsequent in vivo evaluation using various behavior pharmacological assays, an anxiolytic effect of these novel diphenylpyrazolinyl ureas was found in the elevated x-maze with an ED50 of 1.7 mg/kg. In the despair swimming test, a model for testing antidepressants, an ED50 of 0.69 mg/kg was determinated for urea 5e and the antidepressant effect had a magnitude comparable to desimipramine.

IL-11 is a parietal cell cytokine that induces atrophic gastritis

Background and AimsIL-is important in gastric damage, mucosal repair and gastric cancer progression. We analysed IL-11 expression in H.pylori infected mouse stomach, the site of gastric IL-11 expression in mice...

Suppression of cAMP-dependent gene expression by cholecystokinin in the hippocampus

Our previous study suggests that "the neuropeptidergic system" might promote a diversity of the mechanisms that regulate signal transmission in the hippocampus. Cholecystokinin (CCK) is the mostly expressed neuropeptide gene in the hippocampus. Here, we investigated whether CCK regulates immediate-early genes (Egr1/zif268 and Fos), critical indicators of cortical neuronal activity. We showed that CCK increased Egr1/zif268 promoter activity in a neuronal cell line, which is transfected with CCK(B) receptor. Unexpectedly, in living hippocampal slices, CCK significantly suppressed cAMP-induced expression of Egr1/zif268 and Fos through CCK(B) receptor activation. This suppression was involved in activating GABA(B) and cannabinoid 1 receptors. In addition to transient CCK modulation of action potentials on hippocampal principal neurons, we suggest that release of endogenous CCK might indirectly produce the suppression of cAMP-dependent gene expression in the hippocampus.

Abstract 1110: Differential expression of cholecystokinin receptors and their ligands in normal and neoplastic pancreas

Abstract Background: The gastrointestinal peptide gastrin has been identified in fetal pancreas up until week 14 where it is thought to play a role in growth and differentiation. Gastrin has also been identified as an important growth factor that stimulates pancreatic cancer through the CCK-B and CCK-C receptors by an autocrine mechanism. Hypothesis: It is hypothesized that gastrin re-expression is important to pancreatic carcinogenesis. Methods: The mRNA from normal human pancreas tissue was isolated and endpoint RT-PCR was performed to detect RNA levels of gastrin and CCK peptide, using gastrin specific and CCK peptide specific primers, respectively. PCR products were visualized on an ethidium bromide stained gel after electrophoresis. Normal human pancreatic tissue samples were evaluated for gastrin and CCK by immunohistochemistry. Tissues were flash frozen and sectioned at a thickness of 8-10uM. Non-specific sites were blocked, followed by exposure to either gastrin or CCK antisera. Peptide presence was assessed using AF568 (Alexa Fluor) goat anti-rabbit secondary antibody. Results: The end-point RT-PCR showed significant levels of CCK-B receptor and CCK peptide in normal pancreas samples. The gastrin end-point RT-PCR showed extremely low levels in all of the normal pancreas samples. Gastrin immunoreactivity was not detected in normal pancreas, however, staining of the positive control, an islet cell tumor, was reactive. The negative control, a GIST tumor, showed no staining as well. Conclusions: Normal pancreas possesses the receptor CCK-B and the peptide CCK. Gastrin is not present in normal pancreatic tissues, but is detected in neoplastic pancreatic samples. Therefore, the re-expression of gastrin plays a pivotal role in the development of pancreatic cancer and could be a potential trigger to pancreatic carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1110. doi:10.1158/1538-7445.AM2011-1110

Preparation of dipeptoid mimetics for the tetrapeptide cholecystokinin, CCK(30-33).

The diastereoselective synthesis of 2,3-methanophenylalanine methyl esters (5) has been achieved in 58% yield. The preparation of the dehydropeptides (1, R = Me; 2, R = H) and the cyclopropylpeptides (3, R = Me; 4, R = H) possessing good binding affinities for the CCK-A and CCK-B receptors is described. Conformational studies of the dipeptide esters 1 and 3 indicated the presence of a beta-turn within the peptide backbone, although there was no preference in type. The Phe and Trp moieties, however, did prefer to be situated on the same side of the peptide turn which is favourable for receptor binding.

Synthesis and biological evaluation of new 3-aralkylamino-2-aryl-2H-1, 2,4-pyridothiadiazine 1,1-dioxides as potential CCK-receptor ligands.

A series of 2-aralkyl-4H-pyridothiadiazine 1,1-dioxides and 3-aralkylamino-2-aryl-2H-pyrido[4,3-e]-1,2,4-thiadiazine 1,1-dioxides structurally related to quinazolinone CCK receptor antagonists were synthesized and evaluated as CCK-A and CCK-B receptor ligands. The compounds were effective as cholecystokinin-ligands in the micromolar range of concentration, c.f. the cholecystokinin receptor antagonists asperlicin, lorglumide or benzotript, and were thus less potent than the best quinazolinones previously reported. Although the compounds were unsuitable for drug use, the work contributed to our understanding of the chemistry of unusual 2,3-disubstituted pyridothiadiazinedioxides.