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Molecules (Basel, Switzerland) Jun 2022The gastrin-releasing peptide receptor (GRPR) is a G-protein-coupled receptor that is overexpressed in many solid cancers and is a promising target for cancer imaging...
The gastrin-releasing peptide receptor (GRPR) is a G-protein-coupled receptor that is overexpressed in many solid cancers and is a promising target for cancer imaging and therapy. However, high pancreas uptake is a major concern in the application of reported GRPR-targeting radiopharmaceuticals, particularly for targeted radioligand therapy. To lower pancreas uptake, we explored Ga-complexed TacsBOMB2, TacsBOMB3, TacsBOMB4, TacsBOMB5, and TacsBOMB6 derived from a potent GRPR antagonist sequence, [LeuψThz]Bombesin(7-14), and compared their potential for cancer imaging with [Ga]Ga-RM2. The K(GRPR) values of Ga-TacsBOMB2, Ga-TacsBOMB3, Ga-TacsBOMB4, Ga-TacsBOMB5, Ga-TacsBOMB6, and Ga-RM2 were 7.08 ± 0.65, 4.29 ± 0.46, 458 ± 38.6, 6.09 ± 0.95, 5.12 ± 0.57, and 1.51 ± 0.24 nM, respectively. [Ga]Ga-TacsBOMB2, [Ga]Ga-TacsBOMB3, [Ga]Ga-TacsBOMB5, [Ga]Ga-TacsBOMB6, and [Ga]Ga-RM2 clearly show PC-3 tumor xenografts in positron emission tomography (PET) images, while [Ga]Ga-TacsBOMB5 shows the highest tumor uptake (15.7 ± 2.17 %ID/g) among them. Most importantly, the pancreas uptake values of [Ga]Ga-TacsBOMB2 (2.81 ± 0.78 %ID/g), [Ga]Ga-TacsBOMB3 (7.26 ± 1.00 %ID/g), [Ga]Ga-TacsBOMB5 (1.98 ± 0.10 %ID/g), and [Ga]Ga-TacsBOMB6 (6.50 ± 0.36 %ID/g) were much lower than the value of [Ga]Ga-RM2 (41.9 ± 10.1 %ID/g). Among the tested [LeuψThz]Bombesin(7-14) derivatives, [Ga]Ga-TacsBOMB5 has the highest tumor uptake and tumor-to-background contrast ratios, which is promising for clinical translation to detect GRPR-expressing tumors. Due to the low pancreas uptake of its derivatives, [LeuψThz]Bombesin(7-14) represents a promising pharmacophore for the design of GRPR-targeting radiopharmaceuticals, especially for targeted radioligand therapy application.
Topics: Animals; Bombesin; Cell Line, Tumor; Gallium Radioisotopes; Humans; Pancreas; Positron-Emission Tomography; Radiopharmaceuticals; Receptors, Bombesin
PubMed: 35744904
DOI: 10.3390/molecules27123777 -
The Journal of Physiology Aug 2015Retinoic acid (RA) and ghrelin levels are altered in human hypoplastic lungs when compared to healthy lungs. Although considerable data have been obtained about RA,...
KEY POINTS
Retinoic acid (RA) and ghrelin levels are altered in human hypoplastic lungs when compared to healthy lungs. Although considerable data have been obtained about RA, ghrelin and bombesin in the congenital diaphragmatic hernia (CDH) rat model, neuroendocrine factors have never been associated with the RA signalling pathway in this animal model. In this study, the interaction between neuroendocrine factors and RA was explored in the CDH rat model. The authors found that normal fetal lung explants treated with RA, bombesin and ghrelin showed an increase in lung growth. Hypoplastic lungs presented higher expression levels of the RA receptors α and γ. Moreover bombesin and ghrelin supplementation, in vitro, to normal lungs increased RA receptor α/γ expression whereas administration of bombesin and ghrelin antagonists to normal and hypoplastic lungs decreased it. These data reveal for the first time that there is a link between neuroendocrine factors and RA, and that neuroendocrine factors sensitise the lung to the RA action through RA receptor modulation.
ABSTRACT
Congenital diaphragmatic hernia (CDH) is characterised by a spectrum of lung hypoplasia and consequent pulmonary hypertension, leading to high morbidity and mortality rates. Moreover, CDH has been associated with an increase in the levels of pulmonary neuroendocrine factors, such as bombesin and ghrelin, and a decrease in the action of retinoic acid (RA). The present study aimed to elucidate the interaction between neuroendocrine factors and RA. In vitro analyses were performed on Sprague-Dawley rat embryos. Normal lung explants were treated with bombesin, ghrelin, a bombesin antagonist, a ghrelin antagonist, dimethylsulfoxide (DMSO), RA dissolved in DMSO, bombesin plus RA and ghrelin plus RA. Hypoplastic lung explants (nitrofen model) were cultured with bombesin, ghrelin, bombesin antagonist or ghrelin antagonist. The lung explants were analysed morphometrically, and retinoic acid receptor (RAR) α, β and γ expression levels were assessed via Western blotting. Immunohistochemistry analysis of RAR was performed in normal and hypoplastic lungs 17.5 days post-conception (dpc). Compared with the controls, hypoplastic lungs exhibited significantly higher RARα/γ expression levels. Furthermore considering hypoplastic lungs, bombesin and ghrelin antagonists decreased RARα/γ expression. Normal lung explants (13.5 dpc) treated with RA, bombesin plus RA, ghrelin plus RA, bombesin or ghrelin exhibited increased lung growth. Moreover, bombesin and ghrelin increased RARα/γ expression levels, whereas the bombesin and ghrelin antagonists decreased RARα/γ expression. This study demonstrates for the first time that neuroendocrine factors function as lung growth regulators, sensitising the lung to the action of RA through up-regulation of RARα and RARγ.
Topics: Animals; Bombesin; Ghrelin; Hernias, Diaphragmatic, Congenital; Lung; Rats; Rats, Sprague-Dawley; Retinoid X Receptor alpha; Retinoid X Receptor gamma
PubMed: 26096456
DOI: 10.1113/JP270477 -
Journal of Nuclear Medicine : Official... Jan 2005Regulatory peptide receptors are overexpressed in numerous human cancers. These receptors have been used as molecular targets by which radiolabeled peptides can localize... (Review)
Review
Regulatory peptide receptors are overexpressed in numerous human cancers. These receptors have been used as molecular targets by which radiolabeled peptides can localize cancers in vivo and, more recently, to treat cancers with peptide receptor radiation therapy (PRRT). This review describes the candidate tumors eligible for such radiotherapy on the basis of their peptide receptor content and discusses factors in PRRT eligibility. At the present time, PRRT is performed primarily with somatostatin receptor- and cholecystokinin-2 (CCK2)-receptor-expressing neuroendocrine tumors with radiolabeled octreotide analogs or with radiolabeled CCK2-selective analogs. In the future, PRRT may be extended to many other tumor types, including breast, prostate, gut, pancreas, and brain tumors, that have recently been shown to overexpress several other peptide receptors, such as gastrin-releasing peptide-, neurotensin-, substance P-, glucagon-like peptide 1-, neuropeptide Y-, or corticotropin-releasing factor-receptors. A wide range of radiolabeled peptides is being developed for clinical use. Improved somatostatin or CCK(2) analogs as well as newly designed bombesin, neurotensin, substance P, neuropeptide Y, and glucagon-like peptide-1 analogs offer promise for future PRRT.
Topics: Animals; Biomarkers, Tumor; Bombesin; Cholecystokinin; Clinical Trials as Topic; Drug Delivery Systems; Drug Evaluation, Preclinical; Humans; Neoplasms; Peptides; Practice Guidelines as Topic; Practice Patterns, Physicians'; Radioisotopes; Radiopharmaceuticals; Receptors, Peptide; Somatostatin; Substance P; Treatment Outcome
PubMed: 15653654
DOI: No ID Found -
American Journal of Respiratory and... Nov 2007The incidence of bronchopulmonary dysplasia (BPD), a chronic lung disease of newborns, is paradoxically rising despite medical advances. We demonstrated elevated...
RATIONALE
The incidence of bronchopulmonary dysplasia (BPD), a chronic lung disease of newborns, is paradoxically rising despite medical advances. We demonstrated elevated bombesin-like peptide levels in infants that later developed BPD. In the 140-day hyperoxic baboon model of BPD, anti-bombesin antibody 2A11 abrogated lung injury.
OBJECTIVES
To test the hypothesis that bombesin-like peptides mediate BPD in extremely premature baboons (born at Gestational Day 125 and given oxygen pro re nata [PRN], called the 125-day PRN model), similar to "modern-day BPD."
METHODS
The 125-day animals were treated with 2A11 on Postnatal Day 1 (P1), P3, and P6. On P14 and P21, lungs were inflation-fixed for histopathologic analyses of alveolarization. Regulation of angiogenesis by bombesin was evaluated using cultured pulmonary microvascular endothelial cells.
MEASUREMENTS AND MAIN RESULTS
In 125-day PRN animals, urine bombesin-like peptide levels at P2-3 are directly correlated with impaired lung function at P14. Gastrin-releasing peptide (the major pulmonary bombesin-like peptide) mRNA was elevated eightfold at P1 and remained high thereafter. At P14, 2A11 reduced alveolar wall thickness and increased the percentage of secondary septa containing endothelial cells. At P21, 2A11-treated 125-day PRN animals had improved alveolarization according to mean linear intercepts and number of branch points per millimeter squared. Bombesin promoted tubulogenesis of cultured pulmonary microvascular endothelial cells, but cocultured fetal lung mesenchymal cells abrogated this effect.
CONCLUSIONS
Early bombesin-like peptide overproduction in 125-day PRN animals predicted alveolarization defects weeks later. Bombesin-like peptide blockade improved septation, with the greatest effects at P21. This could have implications for preventing BPD in premature infants.
Topics: Animals; Animals, Newborn; Bombesin; Bronchopulmonary Dysplasia; Cell Culture Techniques; Disease Models, Animal; Endothelial Cells; Gastrin-Releasing Peptide; Humans; Infant, Newborn; Neovascularization, Pathologic; Papio; Pulmonary Alveoli; RNA, Messenger
PubMed: 17585105
DOI: 10.1164/rccm.200611-1734OC -
International Journal of Cancer Oct 2010Bombesin (BN) and gastrin-releasing peptide (GRP) have been shown to stimulate the growth of human prostate cancer in vivo and in vitro by mechanisms initiated by...
Bombesin (BN) and gastrin-releasing peptide (GRP) have been shown to stimulate the growth of human prostate cancer in vivo and in vitro by mechanisms initiated by binding of the peptide to BN/GRP receptor (GRPR). GRPR is overexpressed in a variety of human cancers, including human prostatic carcinoma. This led us to evaluate the effectiveness of blocking GRPR and of chemotherapy targeted to GRPR in androgen-dependent (LNCaP) and androgen-independent (PC-3) prostate cancer cells, which exhibit different features of disease progression. Thus, we used a cytotoxic BN/GRP analog, AN-215, consisting of 2-pyrrolinodoxorubicin (AN-201) linked to BN-like carrier peptide, and a BN/GRP receptor antagonist, RC-3095. Semiquantitative RT-PCR and Western blotting revealed that mRNA and protein levels for GRPR increased in prostate cancer cells as compared with nonneoplastic RWPE-1 cells. Immunofluorocytochemistry and Western blot assays revealed that AN-215 was the most effective analog decreasing both the expression of epidermal growth factor receptor family members and the activation of epidermal growth factor receptor and HER-2, which are associated to a poor prognosis. Furthermore, analogs targeted to BN/GRP receptors, AN-215 and RC-3095, blocked the effect of BN on cell growth in RWPE-1, LNCaP and PC-3 cells. These findings shed light on the mechanisms of action of these analogs and support the view that the use of AN-215 and RC-3095 for blocking BN/GRP receptors for targeted therapy may be of benefit for treatment of advanced prostate cancer.
Topics: Antineoplastic Agents; Apoptosis; Blotting, Western; Bombesin; Cell Proliferation; Doxorubicin; Gene Expression Regulation, Neoplastic; Humans; Immunoenzyme Techniques; Male; Peptide Fragments; Prostatic Neoplasms; RNA, Messenger; Receptor, ErbB-2; Reverse Transcriptase Polymerase Chain Reaction; Transcriptional Activation; Tumor Cells, Cultured
PubMed: 20099275
DOI: 10.1002/ijc.25192 -
British Journal of Cancer Nov 1994We investigated the effects of our synthetic bombesin/gastrin-releasing peptide (GRP) antagonists and somatostatin analogue RC-160 on the growth of human small-cell lung...
Effects of somatostatin analogue RC-160 and bombesin/gastrin-releasing peptide antagonists on the growth of human small-cell and non-small-cell lung carcinomas in nude mice.
We investigated the effects of our synthetic bombesin/gastrin-releasing peptide (GRP) antagonists and somatostatin analogue RC-160 on the growth of human small-cell lung carcinoma (SCLC) and non-small-cell lung carcinoma (non-SCLC) lines in nude mice. Athymic nude mice bearing xenografts of the SCLC NCl-H69 line or non-SCLC NCl-H157 line were treated for 5 and 4 weeks, respectively, with somatostatin analogue RC-160 or various bombesin/GRP antagonists. RC-160, administered s.c. peritumorally at a dose of 100 micrograms per animal per day, inhibited the growth of H69 SCLC xenografts as shown by more than 70% reduction in tumour volumes and weights, as compared with the control group. Bombesin/GRP antagonists, RC-3440, RC-3095 and RC-3950-II, given s.c. peritumorally at a dose of 20 micrograms per animal per day, also inhibited the growth of H69 SCLC tumours. RC-3950-II had the greatest inhibitory effect and decreased tumour volume and weights by more than 80%. The growth of H-157 non-SCLC xenografts was significantly reduced by treatment with RC-160, but not with bombesin/GRP antagonist RC-3095. In mice bearing either tumour model, administration of RC-160 significantly decreased serum growth hormone and gastrin levels. Specific high-affinity receptors for bombesin and somatostatin were found on membranes of SCLC H69 tumours, but not on non-SCLC H157 tumours. Receptor analyses demonstrated high-affinity binding sites for epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) on the membranes of H69 and H157 tumours. EGF receptors were down-regulated on H69 tumours after treatment with RC-160 and bombesin/GRP antagonists. The concentration of binding sites for EGF and IGF-I on the H157 tumours was decreased after treatment with RC-160, but bombesin/GRP antagonist RC-3095 had no effect. These results demonstrate that bombesin/GRP antagonists inhibit the growth of H-69 SCLC, but not of H-157 non-SCLC xenografts in nude mice, whereas somatostatin analogue RC-160 is effective in both tumour models. This raises the possibility that these peptide analogues could be used selectively in the treatment of various subclasses of lung cancer.
Topics: Amino Acid Sequence; Animals; Antineoplastic Agents; Binding Sites; Body Weight; Bombesin; Carcinoma, Non-Small-Cell Lung; Carcinoma, Small Cell; Cell Division; Gastrin-Releasing Peptide; Gastrins; Gonadotropin-Releasing Hormone; Growth Hormone; Humans; Lung Neoplasms; Male; Mice; Mice, Nude; Molecular Sequence Data; Neoplasm Transplantation; Peptide Fragments; Peptides; Receptors, Somatotropin; Somatostatin; Substrate Specificity; Transplantation, Heterologous
PubMed: 7947094
DOI: 10.1038/bjc.1994.415 -
Proceedings of the National Academy of... May 1983Bombesin is shown to be a potent mitogen for Swiss 3T3 cells. At nanomolar concentrations the peptide markedly enhances the ability of fresh serum to stimulate DNA...
Bombesin is shown to be a potent mitogen for Swiss 3T3 cells. At nanomolar concentrations the peptide markedly enhances the ability of fresh serum to stimulate DNA synthesis in confluent and quiescent cultures of these cells. In the presence of a low concentration (3.5%) of serum, bombesin stimulates 3T3 cell proliferation. In serum-free medium, bombesin induces DNA synthesis in the absence of any other added growth factor; half-maximal effect is obtained at 1 nM. The mitogenic effect of bombesin is dependent on dose and time, is mimicked by litorin, and is markedly potentiated by insulin, colchicine, platelet-derived growth factor, and fibroblast-derived growth factor. These mitogens increase the maximal response elicited by bombesin and decrease the bombesin concentration required to produce half-maximal effect (from 1 nM to 0.3 nM). In contrast, vasopressin, phorbol esters, or cAMP increasing agents fail to enhance the maximal level of DNA synthesis induced by bombesin. Bombesin and litorin may provide useful model peptides for studies on the mechanism(s) by which extracellular ligands control cell proliferation.
Topics: Animals; Bombesin; Cell Cycle; Cell Division; Cells, Cultured; Culture Media; DNA Replication; Growth Substances; Insulin; Mice; Mitogens; Peptides
PubMed: 6344074
DOI: 10.1073/pnas.80.10.2936 -
European Journal of Nuclear Medicine... Nov 2023NeoB and RM2 are the most investigated gastrin-releasing peptide receptor (GRPR)-targeting radiotracers in preclinical and clinical studies. Therefore, an extensive... (Comparative Study)
Comparative Study
INTRODUCTION
NeoB and RM2 are the most investigated gastrin-releasing peptide receptor (GRPR)-targeting radiotracers in preclinical and clinical studies. Therefore, an extensive side-by-side comparison of the two radiotracers is valuable to demonstrate whether one has advantages over the other. Accordingly, this study aims to compare the in vitro and in vivo characteristics of radiolabeled NeoB and RM2 to guide future clinical studies.
METHOD
The stability of the radiolabeled GRPR analogs was determined in phosphate buffered saline (PBS), and commercially available mouse and human serum. Target affinity was determined by incubating human prostate cancer PC-3 cells with [Lu]Lu-NeoB or [Lu]Lu-RM2, + / - increasing concentrations of unlabeled NeoB, RM2, or Tyr-bombesin (BBN). To determine uptake and specificity cells were incubated with [Lu]Lu-NeoB or [Lu]Lu-RM2 + / - Tyr-BBN. Moreover, in vivo studies were performed to determine biodistribution and pharmacokinetics. Finally, radiotracer binding to various GRPR-expressing human cancer tissues was investigated.
RESULTS
Both radiotracers demonstrated high stability in PBS and human serum, but stability in mouse serum decreased substantially over time. Moreover, both radiotracers demonstrated high GRPR affinity and specificity, but a higher uptake of [Lu]Lu-NeoB was observed in in vitro studies. In vivo, no difference in tumor uptake was seen. The most prominent difference in uptake in physiological organs was observed in the GRPR-expressing pancreas; [Lu]Lu-RM2 had less pancreatic uptake and a shorter pancreatic half-life than [Lu]Lu-NeoB. Furthermore, [Lu]Lu-RM2 presented with a lower tumor-to-kidney ratio, while the tumor-to-blood ratio was lower for [Lu]Lu-NeoB. The autoradiography studies revealed higher binding of radiolabeled NeoB to all human tumor tissues.
CONCLUSION
Based on these findings, we conclude that the in vivo tumor-targeting capability of radiolabeled NeoB and RM2 is similar. Additional studies are needed to determine whether the differences observed in physiological organ uptakes, i.e., the pancreas, kidneys, and blood, result in relevant differences in organ absorbed doses when the radiotracers are applied for therapeutic purposes.
Topics: Animals; Humans; Male; Mice; Biological Transport; Bombesin; Cell Line, Tumor; Prostatic Neoplasms; Receptors, Bombesin; Tissue Distribution
PubMed: 37584725
DOI: 10.1007/s00259-023-06364-4 -
Proceedings of the National Academy of... Dec 1990Bombesin is a tetradecapeptide originally isolated from frog skin; its mammalian homologue is the 27-amino acid peptide gastrin-releasing peptide (GRP). cDNAs encoding... (Comparative Study)
Comparative Study
Bombesin is a tetradecapeptide originally isolated from frog skin; its mammalian homologue is the 27-amino acid peptide gastrin-releasing peptide (GRP). cDNAs encoding GRP have been cloned from diverse species, but little is yet known about the amphibian bombesin precursor. Mass spectrometry of HPLC-separated skin exudate from Bombina orientalis was performed to demonstrate the existence of authentic bombesin in the skin of this frog. A cDNA library was prepared from the skin of B. orientalis and mixed oligonucleotide probes were used to isolate cDNAs encoding amphibian bombesin. Sequence analysis revealed that bombesin is encoded in a 119-amino acid prohormone. The carboxyl terminus of bombesin is flanked by two basic amino acids; the amino terminus is not flanked by basic amino acids but is flanked by a chymotryptic-like cleavage site. Northern blot analysis demonstrated similarly sized bombesin mRNAs in frog skin, brain, and stomach. Polymerase chain reaction was used to show that the skin and gut bombesin mRNAs encoded the identical prohormones. Prohormone processing, however, differed between skin and gut. Chromatography showed the presence of only authentic bombesin in skin whereas gut extracts contained two peaks of bombesin immunoreactivity, one consistent in size with bombesin and one closer in size to mammalian GRP. Thus the same bombesin prohormone is processed solely to bombesin in skin but is processed to a peptide similar in size to bombesin and to a peptide similar in size to mammalian GRP in stomach.
Topics: Amino Acid Sequence; Animals; Anura; Base Sequence; Bombesin; Chromatography, High Pressure Liquid; Cloning, Molecular; DNA; Gastrin-Releasing Peptide; Mass Spectrometry; Molecular Sequence Data; Peptides; Polymerase Chain Reaction; Sequence Homology, Nucleic Acid; Skin
PubMed: 2263631
DOI: 10.1073/pnas.87.24.9813 -
Chemical & Pharmaceutical Bulletin 2020There are various diagnostic and therapeutic agents for prostate cancer using bombesin (BBN) derivatives, but astatine-211 (At)-labeled BBN derivatives have yet to be...
There are various diagnostic and therapeutic agents for prostate cancer using bombesin (BBN) derivatives, but astatine-211 (At)-labeled BBN derivatives have yet to be studied. This study presented a preliminary evaluation of At-labeled BBN derivative. Several nonradioactive iodine-introduced BBN derivatives (IB-BBNs) with different linkers were synthesized and their binding affinities measured. Because IB-3 exhibited a comparable affinity to native BBN, [At]AB-3 was synthesized and the radiochemical yields of [At]AB-3 was 28.2 ± 2.4%, with a radiochemical purity of >90%. The stability studies and cell internalization/externalization experiments were performed. [At]AB-3 was taken up by cells and internalized; however, radioactivity effluxed from cells over time. In addition, the biodistribution of [At]AB-3, with and without excess amounts of BBN, were evaluated in PC-3 tumor-bearing mice. Despite poor stability in murine plasma, [At]AB-3 accumulated in tumor tissue (4.05 ± 0.73%ID/g) in PC-3 tumor-bearing mice, which was inhibited by excess native BBN (2.56 ± 0.24%ID/g). Accumulated radioactivity in various organs is probably due to free At. Peptide degradation in murine plasma and radioactivity efflux from cells are areas of improvement. The development of At-labeled BBN derivatives requires modifying the BBN sequence and preventing deastatination.
Topics: Animals; Antineoplastic Agents; Astatine; Bombesin; Drug Screening Assays, Antitumor; Humans; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasms, Experimental; PC-3 Cells; Prostatic Neoplasms; Radiopharmaceuticals; Tissue Distribution; Tumor Cells, Cultured
PubMed: 32475858
DOI: 10.1248/cpb.c20-00077