Discovery of exogenous ligands for orphan receptor BRS-3 from Chinese herbs / 中国中药杂志

Bombesin receptor subtype-3(BRS-3) is an orphan receptor in the bombesin receptor family. Its signal transduction mechanism and biological function have attracted much attention. Seeking the ligand for BRS-3 is of great significance for exploring its function. Considering the fact that the activation of BRS-3 receptor can induce the change in intracellular Ca~(2+) concentration, the fluo-rometric imaging plate reader(FLIPR) was utilized for ligand screening at the cellular level. Among more than 400 monomeric compounds isolated from Chinese herbs, yuanhunine from Corydalis Rhizoma and sophoraisoflavanone A and licoriphenone from Glycyrrhizae Radix et Rhizoma antagonized BRS-3 to varying degrees. It was confirmed in HEK293 cells expressing BRS-3 that yuanhunine, sophoraisoflavanone A, and licoriphenone inhibited the calcium current response after the activation of BRS-3 by [D-Phe~6,β-Ala~(11),Phe~(13),Nle~(14)]bombesin-(6-14) in a dose-dependent manner with the IC_(50) values being 8.58, 4.10, and 2.04 μmol·L~(-1), respectively. Further study indicated that yuanhunine and sophoraisoflavanone A exhibited good selectivity for BRS-3. In this study, it was found for the first time that monomers derived from Chinese herbs had antagonistic activity against orphan receptor BRS-3, which has provided a tool for further study of BRS-3 and also the potential lead compounds for new drug discovery. At the same time, it provides reference for the research and development of innovative drugs based on the active ingredients of Chinese herbs.

A Neuromedin B Receptor Blockade Inhibits the Growth of Human Oral Cancer Cells

Neuromedin B (NMB) acts as a growth factor or a morphogen and plays a role in cancer progression. Indeed, the NMB receptor (NMB-R) is overexpressed in different types of tumors. In our current study, we investigated the involvement of NMB-R in the proliferation of oral cancer cells. Human oral squamous cell carcinoma (SCC) and human oral cancer cells, SCC-25 cells were found to be NMB-R-positive. The NMB-R antagonist PD168368 inhibited the proliferation of SCC-25 cells and reduced their colony formation capacity. We also found that PD168368 induced the cell cycle arrest and apoptosis of SCC-25 cells in a dose-/time-dependent manner. Overall, this antitumor activity of PD168368 in human oral cancer cells suggests that NMB-R is a potential target for the future prevention and treatment of human cancers.

Effects of Jiaweisinisan on gastric mucosal ultrastructure and brain-gut axis in a rat model of chronic psychological stress / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effect of Jiaweisinisan (JWSNS), a traditional Chinese herbal medicinal recipe, on gastric mucosal ultrastructure and brain-gut axis in rat models of chronic psychological stress and elucidate the mechanism of JWSNS for ameliorating stress-induced gastrointestinal dysfunction.</p><p><b>METHODS</b>Sixty rats were randomly assigned into normal control group, model group, 3 JWSNS groups (high, moderate, and small doses), and omeprazole group (n=10). Rat models of chronic psychological stress were established by random stressful stimulations, and following the corresponding interventions, plasma adrenocorticotropic hormone (ACTH) and cortisol (CORT) levels were detected using radioimmunoassay, and the mRNA expressions of gastrin receptor in the gastric tissue (GASR) and vasoactive intestinal peptide II receptor (VIPR2) in the jejunal tissue were examined using RT-PCR. Transmission electron microscopy was employed to examine the ultrastructural changes in the gastric mucosa tissue cells of the glandular stomach area and alterations in the intercellular junctions.</p><p><b>RESULTS</b>Electron microscopy revealed obvious damages in gastric mucosal epithelial cell organelles and nuclei in the model rats. These damages were ameliorated after treatments with JWSNS and omeprazole. Compared with the model group, the 3 JWSNS groups and omeprazole group all showed significantly lowered plasma ACTH and CORT levels, increased gastrin receptor mRNA expression and decreased jejunal VIPR2 mRNA expression (P<0.05 or 0.01).</p><p><b>CONCLUSION</b>JWSNS can obviously ameliorate the pathologies of the gastric mucosa cells, regulate the state of brain-gut axis, and modulate the gastric gastrin receptor and jejunal VIPR2 mRNA expressions in rats with chronic psychological stress.</p>

Comparison of two peptide radiotracers for prostate carcinoma targeting

OBJECTIVES: Scintigraphy is generally not the first choice treatment for prostate cancer, although successful studies using bombesin analog radiopeptides have been performed. Recently, a novel peptide obtained using a phage display library demonstrated an affinity for prostate tumor cells. The aim of this study was to compare the use of a bombesin analog to that of a phage display library peptide (DUP-1) radiolabeled with technetium-99m for the treatment of prostate carcinoma. The peptides were first conjugated to S-acetyl-MAG3 with a 6-carbon spacer, namely aminohexanoic acid. METHODS: The technetium-99m labeling required a sodium tartrate buffer. Radiochemical evaluation was performed using ITLC and was confirmed by high-performance liquid chromatography. The coefficient partition was determined, and in vitro studies were performed using human prostate tumor cells. Biodistribution was evaluated in healthy animals at various time points and also in mice bearing tumors. RESULTS: The radiochemical purity of both radiotracers was greater than 95 percent. The DUP-1 tracer was more hydrophilic (log P = -2.41) than the bombesin tracer (log P = -0.39). The biodistribution evaluation confirmed this hydrophilicity by revealing the greater kidney uptake of DUP-1. The bombesin concentration in the pancreas was greater than that of DUP-1 due to specific gastrin-releasing peptide receptors. Bombesin internalization occurred for 78.32 percent of the total binding in tumor cells. The DUP-1 tracer showed very low binding to tumor cells during the in vitro evaluation, although tumor uptake for both tracers was similar. The tumors were primarily blocked by DUP1 and the bombesin radiotracer primarily targeted the pancreas. CONCLUSION: Further studies with the radiolabeled DUP-1 peptide are recommended. With further structural changes, this molecule could become an efficient alternative tracer for prostate tumor diagnosis.

Expression of NMBR in myometrium in pregnant mice at different gestational ages and its relation with parturition / 中南大学学报(医学版)

OBJECTIVE@#To investigate the spatiotemporal expression of neuromedin B receptor (NMBR) in mice myometrium at different pregnant stages, as well as its mechanism and relation with parturition.@*METHODS@#The pregnant mice were divided into no-pregnancy (NP), early pregnancy (EP), mid-pregnancy (MP), late-pregnancy (LP), parturition (PT) and postpartum (PP) groups (12 mice in each group), according to pregnant stage. The mRNA and protein expression of NMBR, HSP70 and IL-6 were detected in myometrium in pregnant mice by semi-quantitative RT-PCR and Western blot, while NF-kappaB-P65 DNA binding activity was determined by NoShift transcription factor assay kits, respectively. Their relation with parturition was analyzed.@*RESULTS@#The mRNA expression level of NMBR in the PT group was significantly higher than that in the NP, EP, LP and PP groups (P0.05). The NMBR protein in PT group was significantly higher than that in the other 5 groups (P<0.01). NF-kappaB-P65 DNA binding activity at PT group was remarkably higher than that in the NP, LP and PP groups (P<0.05). The expression of IL-6 mRNA was significantly higher than that in the NP, LP and PP groups (P<0.05), its protein expression in PT and LP groups was significantly higher than that in the NP and PP groups (P<0.05). The expression of HSP70 mRNA in the PT group was significantly higher than that in the NP and PP groups (P<0.05), and the protein of HSP70 was significantly up-regulated in PT and PP groups compared with in NP and LP groups (P<0.05). The DNA-binding activity of P65 was positively correlated to the mRNA expression of NMBR and IL-6 (r=0.40, P<0.01; r=0.30, P<0.05), so were positively correlated to DNA-binding activity of P65, mRNA expression of HSP70 and NMBR ( r=0.40, P<0.01; r=0.49, P<0.01). DNA-binding activity of P65 did not correlate with the mRNA expression of HSP70.@*CONCLUSION@#The mRNA and protein expressions of NMBR reach a peak at the onset of labor. NMBR may play an important role in the parturition via NF-kappaB P65-IL-6 signal transduction pathway. It may also influence the onset of labor by regulating HSP70, but this role does not rely on P65 pathway.

Synthesis and evaluation of a new radiolabeled bombesin analogue for diagnosis of GRP receptor expressing tumors

Bombesin [BN], a 14-amino acid neuropeptide, shows high affinity for the human GRP [gastrin releasing peptide] receptors, which are overexpressed by a variety of cancers, including prostate, breast, pancreas, gastrointestinal, and small cell lung cancer. Aim was to prepare [6-hydrazinopyridine-3-carboxylic acid [HYNIC[0], D-Tyr[6], D-Trp[8]] - BN [6-14] NH[2] that could be easily labeled with[99m]Tc and evaluation of its potential as an imaging agent. Synthesis of the peptide amide was carried out onto Rink Amide MB HA [4-Methylbenzhydrylamine] resin. A bifunctional chelating agent [BFCA] was attached to the N terminal peptide in solid-phase. [99m]Tc labeling was performed by addition of sodium pertechnetate to solution that include [HYNIC[0], D-Tyr[6], D-Trp[8]] Bombesin [6-14] NH[2], tricine, ethylenediamine-N,N'-diaeetic acid [EDDA] and SnCl[2]. Radiochemical evaluation was carried out by reverse phase high-performance liquid chromatography [HPLC] and instant thin layer chromatography [ITLC]. In- vitro internalization was tested using human prostate cancer cells [PC-3] with blocked and non-blocked receptors. Biodistribution was determined in rats. [99m]Tc/tricine/EDDA-HYNIC[0], D-Tyr[6], D-Trp[8]] bombesin [6-14] NH[2] was obtained with radiochemical purities >98%. Results of in-vitro studies demonstrated a high stability in serum and suitable internalization. Biodistribution data showed a rapid blood clearance, with renal excretion and specific binding towards GRP receptor-positive tissues such as pancreas. In this study, labeling of this novel conjugate with [99m] Tc easily was performed using coligand. The prepared [99m]Tc-HYNIC-BN conjugate has promising characteristics for the diagnosis of malignant tumors

Advances in the study of small peptides in targeted drug delivery system / 药学学报

Recently various peptide receptors which displayed the highest binding affinity and specificity with their peptide ligands by ligand-receptor have been exploited to develop drug delivery system which can directionally deliver drug to targeted cell. It is significant to study and applicate, including targeted drug delivery system mediated by bombesin receptor, somatostatin receptor, SynB3 receptor, LH-RH receptor and other peptide receptor, et al. Several small peptide fragments were selected as carriers radicals combining doxorubicin, 2-pyrrolino-DOX, methotrexate, cis-platinum, and camptothecin to form hybrid cytotoxic analogs. These highly potent cytotoxic analogs have been designed as targeted anti-tumor agents for the treatment and study of various cancers that possess receptors for the carrier peptide.

Scanning of drug targets related to uterus contraction from the uterine smooth muscles by cDNA microarray / 中南大学学报(医学版)

OBJECTIVE@#To screen the differentially expressed gene profile from the smooth muscles in the fundus uterus at the active stage of labor, and to provide candidate genes for picking out the drug targets related to uterine contraction.@*METHODS@#Differentially expressed genes of uterine smooth muscles in the corpus from pro and post spontaneous parturition and those induced by oxytocin,as well as those from the corpus and the lower portion spontaneous parturition,were scanned respectively by human full-length genetic cDNA microarray with 8064 probe sets. Semi-quantitative RT-PCR was applied to testify the expression of voltage dependent calcium channel-L subtype (CACNA). The differentially expressed genes in the structure and function of the drug targets were picked out by bio-informatics to serve as candidate drug targets related to uterine contraction.@*RESULTS@#The expressions of 29 genes were upregulated in fundus smooth muscles from the pro and post natural parturition, the pro and post inductive parturition of oxytocin, and the natural parturition. The expression of CACNA gene in RT-PCR was in accordance with that in the microarray. Among the 29 genes, neuromedin B receptor (NMBR) gene and neuropeptide Y (NPY) gene were the genes which not only had the targets of uterine contracted medicine, but also could contract the uterine. The differential expression ratios of NMBR in the above 3 types of uterine myometrium were 6.9,11.3, and 9.0, respectively while those of NPY were 6.0,29.8, and 2.9 respectively.@*CONCLUSION@#NMBR, whose expression in the uterine smooth muscles is always up-regulated at different parturition conditions, is likely to be an ideal candidate target of uterotonic drugs.

Protective effect of bombesin receptor subtype-3 on human brochial epithelial cells against injury / 中南大学学报(医学版)

OBJECTIVE@#To investigate the role and mechanism of bombesin receptor subtype 3 (BRS-3) in the proliferation and protection against injury of human brochial epithelial cells (HBECs).@*METHODS@#Effect of P3513 (a specific agonist of BRS-3) on the proliferation of HBECs was observed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method; the release rate of 3H-Udr, and LDH activity, catalase activity, and the expression of cadherin and integrin beta1 were also analyzed under O3 stress with or without P3513 treatment.@*RESULTS@#The proliferation of HBECs was accelerated by P3513 in a concentration-dependent manner (10(-9) approximately 10(-7) mol/L). Ozone stress could promote the release rate of 3H-Udr, and LDH activity, which could be inhibited by P3513. P3513 could promote the activity of catalase. The effect of proliferation and protection against injury caused by P3513 could be inhibited by W7 (calmodulin inhibitor), PD98059 (tyrosin kinase inhibitor) and H89 (PKA inhibitor). P3513 could stimulate the expression of caderin and integrinbeta1 of ozone-stressed HBECs.@*CONCLUSION@#Activation of BRS-3 caused by P3513 may play an important role in protecting HBECs from oxidant injury, and the signal pathway is possibly relevant to Ca2+, MEK and PKA.

Bombesina y bombesinas radiomarcadas: estado actual / Bombesin and radiolabeled bombesin: current status

El péptido bombesina (BN), de 14 amino ácidos, se aisló de la piel de los batracios y forma parte de un amplio grupo de neuropéptidos con diversas funciones biológicas. El homólogo equivalente en los mamíferos es el péptido liberador de la gastrina (GRP) y sus receptores (GRP-r) se expresan abundantemente en la membrana de las células tumorales, estimulando su crecimiento. La unión BN-GRP-r es una fuerte unión altamente específica por lo cual la BN marcada con radionucleidos se ha utilizado en medicina nuclear para la localización de tumores malignos de cáncer de mama y próstata principalmente. Las modificaciones en la cadena peptídica y el marcado se llevan a cabo en la región de extremo-N inicial, quedando el extremo C-terminal con su especificidad y acción biológica intactas. Se presentan varios análogos de BN radiactivos y la estructura de uno nuevo formado por un conjugado EDDA/HYNIC-BBN que fácilmente se une al 99mTc. Las expectativas para utilizar radiofármacos de BN marcados con emisores beta-negativos en radiopéptidoterapia son grandes y prometedoras.

Peptídeos bombesina-símiles: novos reguladores da secreçäo adeno-hipofisária / Bombesin-similes peptides: news regulatory of adenohypophyseal secretion

A neuromedina B (NB) e o peptídeo liberador de gastrina são peptídeos bombesina-símiles encontrados em mamíferos, inclusive em seres humanos. Ambos inibem a secreção hipofisária de tireotrofina (TSH); entretanto, somente a NB tem importância fisiológica demonstrada. A NB é produzida em abundância em tireotrofos e parece inibir a secreção de TSH por via autócrina, uma vez que o bloqueio do peptídeo endógeno causa aumento na liberação do TSH, tanto in vivo quanto in vitro. A NB é positivamente regulada pelos hormônios tireóideos (HT). Os HT aumentam o conteúdo de neuromedina B e do seu RNAm em adeno-hipófises de ratos hipotireóideos, poucas horas após sua administração, o que coincide com diminuição do TSH sérico. Isto nos levou a sugerir que a NB possa ser um intermediário protéico envolvido na inibição aguda da liberação de TSH induzida pelos HT. O TRH também altera rapidamente a expressão da NB. Quinze e 30 minutos após a administração do TRH em ratos normais já há diminuição do conteúdo hipofisário de NB e dos níveis do seu RNAm. No jejum e diabetes experimental, que se caracterizam por diminuição de HT séricos com níveis inadequadamente normais ou diminuídos de TSH, ocorre aumento do conteúdo de NB e de seu RNAm. O análogo de somatostatina, octreotide, também é capaz de aumentar o conteúdo de NB. Assim, a neuromedina B é um importante inibidor local da secreção de TSH, podendo ser uma via final comum de hormônios e neuro-hormônios que determinam variações na secreção de TSH.

Interaction between substance P and gastrin-releasing peptide on thyrotropin secretion by rat pituitary in vitro

The effect of substance P (SP) on thyrotropin (TSH) secretion is controversial. In this study we evaluated the effect of SP on TSH secretion by hemipituitaries of 3-month-old Wistar rats in vitro and its interaction with gastrin-releasing peptide (GRP) at equimolar concentrations (1 µM and 10 µM). TSH release was measured under basal conditions and 30 min after incubation in the absence or presence of SP, GRP or both peptides. Pituitary TSH content was also measured in the pituitary homogenate after incubation. SP at both concentrations caused a significant (P<0.05) increase in TSH secretion compared with all other groups, which was approximately 60 percent (1 µM) and 85 percent (10 µM) higher than that of the control group (23.3 + or - 3.0 ng/ml). GRP at the lower concentration did not produce a statistically significant change in TSH secretion, whereas at the concentration of 10 µM it produced a 50 percent reduction in TSH. GRP co-incubated with substance P completely blocked the stimulatory effect of SP at both concentrations. Pituitary TSH content decreased in the SP-treated group compared to controls (0.75 + or - 0.03 µg/hemipituitary) at the same proportion as the increase in TSH secretion, and this effect was also blocked when GRP and SP were co-incubated. In conclusion, in an in vitro system, SP increased TSH secretion acting directly at the pituitary level and this effect was blocked by GRP, suggesting that GRP is more potent than SP on TSH secretion, and that this inhibitory effect could be the predominant effect in vivo

Acute effect of thyroxine on pituitary neuromedin B content of hypothyroid rats and its correlation with TSH secretion

Neuromedin B (NB) is a bombesin-like peptide that has been recently characterized as a physiological paracrine/autocrine inhibitor of thyrotropin (TSH) secretion. We report here the time course of the effect of thyroxine (T4) administration to hypothyroid rats on the anterior pituitary content of NB. Dutch-Miranda male rats weighing 250-300 g received 0.03 percent methimazole in the drinking water for 3 weeks. T4(0.8µg/100 g body weigh, sc) was given 1/2, 1,2 or 6 h before sacrifice. One group recived saline rather than T4 (hypothyroid control). The groups contained 6 to 8 animals each. NB, extracted from tissue by boiling in acetic acid, was measured by radioimmunoassay, using a highly specific anti-serum. Pituitary NB content was significantly increased 4-fold, as ealry 1/2 h after T4 injection, while serum TSH level was similar to that of the hypophyroid control group. The peak response to T4 was at 4 h after injection, when NB content was increased 8-fold (hypothyroid: 45 ñ 8; 1/2h, 223 ñ 15; 1h, 203 ñ 48; 3h, 383 ñ 31; 6h, 224 ñ 30 fmol/mg protein) and serum TSH decreased to the level of normal rats (0.93-1.5 ng/ml) generally observed in our laboratory (jypothyroid: 31 ñ 3; 1/2h, 26 ñ 3; 1h, 31 ñ 2; 3h, 1.3 ñ 0.1; 6h, 3.7 ñ 0.6 ng/ml). These data suggest that NB synthesis is rapidly induced by thyroxine and this might represent a new regulatory pathy involved in the acute inhibitory effect of thyroid hormones on TSH secretion

Study of some hormonal aspects in acute and chronic peptic ulcer

The role played by some gastrointestinal hormones [Gastrin and Bombesin] in the pathogenesis of peptic ulcer disease was studied in 50 patients with peptic ulcer diagnosed endoscopically,5 oesophageal, 6 gastric, 39 dudenal and 20 control subjects. Fasting serum gastrin was elevated in gastric ulcer group as compared to controls and this was due to a reflection of the generally lower rate of acid secretion in these patients. Oesophageal ulcer patients also had higher levels compared to controls, but the difference was not statistically significant. No significant difference could be found between dudenal ulcer patients and controls. Serum bombesin was lower in all the types of peptic ulcer relative to the control. The low serum bombesin level in gastric ulcer group corresponds with the finding of high serum gastrin in these patients. Bombesin is found to be a potent releaser of gastrin in man and gastrin exerts a feed back inhibitory mechanism on bombesin level. The finding of low serum bombesin with normal fasting gastrin in dudenal ulcer patients indicates that the feed back inhibitory mechanism of elevated gastrin on bombesin level in these patients is not valid and other factors must be involved