Elevated Serum Gastrin Is Associated with Melanoma Progression: Putative Role in Increased Migration and Invasion of Melanoma Cells.

Micro-environmental factors, including stromal and immune cells, cytokines, and circulating hormones are well recognized to determine cancer progression. Melanoma cell growth was recently shown to be suppressed by cholecystokinin/gastrin (CCK) receptor antagonists, and our preliminary data suggested that melanoma patients with Helicobacter gastritis (which is associated with elevated serum gastrin) might have an increased risk of cancer progression. Therefore, in the present study, we examined how gastrin may act on melanoma cells. In 89 melanoma patients, we found a statistically significant association between circulating gastrin concentrations and melanoma thickness and metastasis, which are known risk factors of melanoma progression and prognosis. Immunocytochemistry using a validated antibody confirmed weak to moderate CCK2R expression in both primary malignant melanoma cells and the melanoma cell lines SK-MEL-2 and G361. Furthermore, among the 219 tumors in the Skin Cutaneous Melanoma TCGA Pan-Cancer dataset showing gastrin receptor (CCKBR) expression, significantly higher CCKBR mRNA levels were linked to stage III-IV than stage I-II melanomas. In both cell lines, gastrin increased intracellular calcium levels and stimulated cell migration and invasion through mechanisms inhibited by a CCK2 receptor antagonist. Proteomic studies identified increased MMP-2 and reduced TIMP-3 levels in response to gastrin that were likely to contribute to the increased migration of both cell lines. However, the effects of gastrin on tumor cell invasion were relatively weak in the presence of the extracellular matrix. Nevertheless, dermal fibroblasts/myofibroblasts, known also to express CCK2R, increased gastrin-induced cancer cell invasion. Our data suggest that in a subset of melanoma patients, an elevated serum gastrin concentration is a risk factor for melanoma tumor progression, and that gastrin may act on both melanoma and adjacent stromal cells through CCK2 receptors to promote mechanisms of tumor migration and invasion.

Effect of GRK4 on renal gastrin receptor regulation in hypertension.

OBJECTIVE: To investigate whether GRK4 regulates the phosphorylation and function of renal CCKBR. METHODS: GRK4 A142V transgenic mice were used as an animal model of enhanced GRK4 activity, and siRNA was used to silence the GRK4 gene to investigate the regulatory effect of GRK4 on CCKBR phosphorylation and function. Finally, the co-localization and co-connection of GRK4 and CCKBR in RPT cells were observed by laser confocal microscopy and immunoprecipitation to explore the mechanism of GRK4 regulating CCKBR. RESULTS: Gastrin infusion significantly increased urinary flow and sodium excretion rates in GRK4 WT mice (P < .05). GRK4 siRNA did not affect CCKBR protein expression in WKY RPT cells and SHR RPT cells, but remarkably reduced CCKBR phosphorylation in WKY and SHR RPT cells (P < .05). The inhibitory effect of gastrin on Na+-K+ -ATPase activity in WKY RPT cells was further enhanced by the reduction of GRK4 expression (P < .05), while GRK4 siRNA restored the inhibitory effect of gastrin on Na+-K+ -ATPase activity in SHR RPT cells. Laser confocal and Co-immunoprecipitation results showed that GRK4 and CCKBR co-localized in cultured RPT cells' cytoplasm. CONCLUSION: GRK4 participates in the development of hypertension by regulating the phosphorylation of renal CCKBR leading to impaired CCKBR function and water and sodium retention. Knockdown of GRK4 restored the function of CCKBR. The enhanced co-connection between GRK4 and CCKBR may be an important reason for the hyperphosphorylation of GRK4 and CCKBR involved in the pathogenesis of hypertension.

Effectiveness of Fuling () and its extracts against spleen deficiency in rats tonifying spleen.

OBJECTIVE: To observe and explore the effect of Fuling () in alleviating the spleen deficiency symptom pattern (SDSP). METHODS: We established an animal model of SDS in Sprague-Dawley () rats by treating them with deficiency-inducing factors, including irregular feeding and tail clamping. Mice were administered Fuling () and its extracts (raw/cooked powder, aqueous/alcohol extract) by gavage once a day for 21 d. The body weight, rectal temperature, and spleen and thymus organ coefficients were calculated. The levels of motilin (MTL), gastrin (GAS), aquaporin 2 (AQP2), interleukin 2 (IL-2), IL-4, and 5-hydroxytryptamine (5-HT) in the serum and the level of AQP2 in the kidneys were evaluated by enzyme-linked immunosorbent assay. RESULTS: Fuling () and its extracts did not change the body weight, rectal temperature, and organ coefficients of the spleen and thymus. However, it reduced the levels of MTL and GAS and increased the levels of IL-2 and AQP2. In addition, the levels of IL-4 and 5-HT showed no significant alteration. CONCLUSIONS: These results suggested the crucial function of () in SDSP, especially promoting digestive function and water metabolism.

Anatomical basis of gastrin- and CCK-secreting cells and their functions. A review.

Gastrin and CCK (cholecystokinin), gut hormones first secreted after postprandial stages, share the C-terminal amino acids and some types of receptors to be stimulated. Both types of hormone-secreting cells are typical open-type cells which detect foods and their digested elements in the lumen and regulate the secretion of gastric acid and digestive enzymes, gut motility, and satiety. Gastrin cell granules are characterized by their heterogenous ultrastructure within the cell, while CCK cell granules show a uniform ultrastructural figure. Gastrin cells are equipped with peptone receptor GPR92, amino acid receptor GPRC6A, and a Ca-sensing receptor. In addition to nutrient receptors, the release of CCK is regulated by a unique negative feedback mechanism. Development of an antibody for CCK-specific receptor (CCK-1R) has revealed its exact localization throughout the body, but specific antibodies against CCK-2R remain unavailable. Gastrin affects differentiation and proliferation-including cancer cells, while CCK possesses trophic effects to target tissues. CCK is a peripheral satiety signal and acts either via the vagus or directly on the dorsal medulla via CCK-1R. In this review, endocrine cells secreting these unique and so-called old gut hormones are described on a morphological basis.

Effects of Quadruple Therapy Combined with Probiotics on Helicobacter Pylori-Related Peptic Ulcer.

The present study was designed to observe the effect of quadruple therapy combined with probiotics on Helicobacter pylori-related peptic ulcer. The patients in the control group (n = 90) were given regular quadruple therapy including proton pump inhibitor ilaprazole enteric-coated tablet + two antibiotics amoxicillin dispersible tablet and metronidazole tablet + colloidal bismuth pectin capsule for 2 weeks. Patients in the study group (n = 90) were given abovementioned quadruple therapy combined with probiotics live combined Bifidobacterium, Lactobacillus, and Enterococcus Capsules, oral for 2 weeks. Then Hp clearance rate, recurrence rate, levels of gastrointestinal hormone makers, and advance reactions between two groups were compared. At the 2nd week after the treatment, the Helicobacter pylori clearance rate in the study group (87.79%) was significantly higher than the control group (78.89%), and the total recurrence rate in the study group (6.67%) was significantly lower than the control group (13.33%) (P < 0.05). Serum gastrin and motilin expression were lower, and somatostatin expressions was significantly higher than those in the control group (P < 0.05). There was no significant difference in the total incidence of adverse reactions between the two groups (P > 0.05). In summary, quadruple therapy combined with probiotics in the treatment of Helicobacter pylori-related peptic ulcer can improve the Helicobacter pylori clearance rate, reduce the Helicobacter pylori recurrence rate, and is beneficial to improving the level of gastrointestinal hormones, with certain safety.

Gastrin exerts a protective effect against myocardial infarction via promoting angiogenesis.

BACKGROUND: It is known that increased gastrin concentration is negatively correlated with cardiovascular mortality, and plasma gastrin levels are increased in patients after myocardial infarction (MI). However, whether gastrin can play a protective role in MI remains unknown. METHODS: Adult C57BL/6 mice were subjected to ligation of the left anterior descending coronary artery (LAD) and subcutaneous infusion of gastrin (120 µg/Kg body weight/day, 100 µL in the pump) for 28 days after MI. Plasma gastrin concentrations were measured through an ELISA detection kit. Mice were analyzed by echocardiography after surgery. CD31 and VEGF expression were quantified using immunofluorescence staining or/and western blot to assess the angiogenesis in peri-infarct myocardium. Capillary-like tube formation and cell migration assays were performed to detect gastrin-induced angiogenesis. RESULTS: We found that gastrin administration significantly ameliorated MI-induced cardiac dysfunction and reduced fibrosis at 28 days in post-MI hearts. Additionally, gastrin treatment significantly decreased cardiomyocyte apoptosis and increased angiogenesis in the infarct border zone without influencing cardiomyocyte proliferation. In vitro results revealed that gastrin up-regulated the PI3K/Akt/vascular endothelial growth factor (VEGF) signaling pathway and promoted migration and tube formation of human coronary artery endothelial cells (HCAECs). Cholecystokinin 2 receptor (CCK2R) mediated the protective effect of gastrin since the CCK2R blocker CI988 attenuated the gastrin-mediated angiogenesis and cardiac function protection. CONCLUSION: Our data revealed that gastrin promoted angiogenesis and improved cardiac function in post-MI mice, highlighting its potential as a therapeutic target candidate.

Gastrin mediates cardioprotection through angiogenesis after myocardial infarction by activating the HIF-1α/VEGF signalling pathway.

Acute myocardial infarction (MI) is one of the leading causes of death in humans. Our previous studies showed that gastrin alleviated acute myocardial ischaemia-reperfusion injury. We hypothesize that gastrin might protect against heart injury after MI by promoting angiogenesis. An MI model was simulated by ligating the anterior descending coronary artery in adult male C57BL/6J mice. Gastrin was administered twice daily by intraperitoneal injection for 2 weeks after MI. We found that gastrin reduced mortality, improved myocardial function with reduced infarct size and promoted angiogenesis. Gastrin increased HIF-1α and VEGF expression. Downregulation of HIF-1α expression by siRNA reduced the proliferation, migration and tube formation of human umbilical vein endothelial cells. These results indicate that gastrin restores cardiac function after MI by promoting angiogenesis via the HIF-1α/VEGF pathway.

Peptidomics of enteroendocrine cells and characterisation of potential effects of a novel preprogastrin derived-peptide on glucose tolerance in lean mice.

OBJECTIVES: To analyse the peptidomics of mouse enteroendocrine cells (EECs) and human gastrointestinal (GI) tissue and identify novel gut derived peptides. METHODS: High resolution nano-flow liquid chromatography mass spectrometry (LC-MS/MS) was performed on (i) flow-cytometry purified NeuroD1 positive cells from mouse and homogenised human intestinal biopsies, (ii) supernatants from primary murine intestinal cultures, (iii) intestinal homogenates from mice fed high fat diet. Candidate bioactive peptides were selected on the basis of species conservation, high expression/biosynthesis in EECs and evidence of regulated secretionin vitro. Candidate novel gut-derived peptides were chronically administered to mice to assess effects on food intake and glucose tolerance. RESULTS: A large number of peptide fragments were identified from human and mouse, including known full-length gut hormones and enzymatic degradation products. EEC-specific peptides were largely from vesicular proteins, particularly prohormones, granins and processing enzymes, of which several exhibited regulated secretion in vitro. No regulated peptides were identified from previously unknown genes. High fat feeding particularly affected the distal colon, resulting in reduced peptide levels from GCG, PYY and INSL5. Of the two candidate novel peptides tested in vivo, a peptide from Chromogranin A (ChgA 435-462a) had no measurable effect, but a progastrin-derived peptide (Gast p59-79), modestly improved glucose tolerance in lean mice. CONCLUSION: LC-MS/MS peptidomic analysis of murine EECs and human GI tissue identified the spectrum of peptides produced by EECs, including a potential novel gut hormone, Gast p59-79, with minor effects on glucose tolerance.

Gastrin-17 induces gastric cancer cell epithelial-mesenchymal transition via the Wnt/ß-catenin signaling pathway.

Gastric cancer (GC) is one of the most common cancers, with most patients often succumbing to death as a result of tumor metastasis. Recent work has demonstrated that gastrin is closely associated with GC metastasis. However, the specific molecular mechanisms underlying this relationship remain to be unveiled. In this study, we assessed the impact of gastrin and the Wnt/ß-catenin inhibitor XAV939 on the epithelial-mesenchymal transition (EMT) of the SGC-7901 and MKN45 GC cell lines, and we determined that gastrin-17 significantly decreased E-cadherin expression and upregulated the expression of Snail1 and N-cadherin in GC cells. In addition, gastrin 17 also significantly increased the expression of Wnt3α in a dose-dependent manner. Consistent with these results, gastrin-17 promoted GC cell invasion, proliferation, and migration in a dose-dependent fashion, and these effects were inhibited by XAV939. Together, these results indicated that gastrin-17 induced GC cell EMT, migration, and invasion via the Wnt/ß-catenin signaling pathway, which suggests that this gastrin/Wnt/ß-catenin signaling axis may represent a therapeutic target for the prevention of GC metastasis.

Gastrin, via activation of PPARα, protects the kidney against hypertensive injury.

Hypertensive nephropathy (HN) is a common cause of end-stage renal disease with renal fibrosis; chronic kidney disease is associated with elevated serum gastrin. However, the relationship between gastrin and renal fibrosis in HN is still unknown. We, now, report that mice with angiotensin II (Ang II)-induced HN had increased renal cholecystokinin receptor B (CCKBR) expression. Knockout of CCKBR in mice aggravated, while long-term subcutaneous infusion of gastrin ameliorated the renal injury and interstitial fibrosis in HN and unilateral ureteral obstruction (UUO). The protective effects of gastrin on renal fibrosis can be independent of its regulation of blood pressure, because in UUO, gastrin decreased renal fibrosis without affecting blood pressure. Gastrin treatment decreased Ang II-induced renal tubule cell apoptosis, reversed Ang II-mediated inhibition of macrophage efferocytosis, and reduced renal inflammation. A screening of the regulatory factors of efferocytosis showed involvement of peroxisome proliferator-activated receptor α (PPAR-α). Knockdown of PPAR-α by shRNA blocked the anti-fibrotic effect of gastrin in vitro in mouse renal proximal tubule cells and macrophages. Immunofluorescence microscopy, Western blotting, luciferase reporter, and Cut&tag-qPCR analyses showed that CCKBR may be a transcription factor of PPAR-α, because gastrin treatment induced CCKBR translocation from cytosol to nucleus, binding to the PPAR-α promoter region, and increasing PPAR-α gene transcription. In conclusion, gastrin protects against HN by normalizing blood pressure, decreasing renal tubule cell apoptosis, and increasing macrophage efferocytosis. Gastrin-mediated CCKBR nuclear translocation may make it act as a transcription factor of PPAR-α, which is a novel signaling pathway. Gastrin may be a new potential drug for HN therapy.

Reversal of autoimmunity by mixed chimerism enables reactivation of ß cells and transdifferentiation of α cells in diabetic NOD mice.

Type 1 diabetes (T1D) results from the autoimmune destruction of ß cells, so cure of firmly established T1D requires both reversal of autoimmunity and restoration of ß cells. It is known that ß cell regeneration in nonautoimmune diabetic mice can come from differentiation of progenitors and/or transdifferentiation of α cells. However, the source of ß cell regeneration in autoimmune nonobese diabetic (NOD) mice remains unclear. Here, we show that, after reversal of autoimmunity by induction of haploidentical mixed chimerism, administration of gastrin plus epidermal growth factor augments ß cell regeneration and normalizes blood glucose in the firmly established diabetic NOD mice. Using transgenic NOD mice with inducible lineage-tracing markers for insulin-producing ß cells, Sox9+ ductal progenitors, Nestin+ mesenchymal stem cells, and glucagon-producing α cells, we have found that both reactivation of dysfunctional low-level insulin expression (insulinlo) ß cells and neogenesis contribute to the regeneration, with the latter predominantly coming from transdifferentiation of α cells. These results indicate that, after reversal of autoimmunity, reactivation of ß cells and transdifferentiation of α cells can provide sufficient new functional ß cells to reach euglycemia in firmly established T1D.

Pharmacological inhibition of mTORC1 increases CCKBR-specific tumor uptake of radiolabeled minigastrin analogue [177Lu]Lu-PP-F11N.

Rationale: A high tumor-to-healthy-tissue uptake ratio of radiolabeled ligands is an essential prerequisite for safe and effective peptide receptor radionuclide therapy (PRRT). In the present study, we searched for novel opportunities to increase tumor-specific uptake of the radiolabeled minigastrin analogue [177Lu]Lu-DOTA-(DGlu)6-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH2 ([177Lu]Lu-PP-F11N), that targets the cholecystokinin B receptor (CCKBR) in human cancers. Methods: A kinase inhibitor library screen followed by proliferation and internalization assays were employed to identify compounds which can increase uptake of [177Lu]Lu-PP-F11N in CCKBR-transfected human epidermoid carcinoma A431 cells and natural CCKBR-expressing rat pancreatic acinar AR42J cells. Western blot (WB) analysis verified the inhibition of the signaling pathways and the CCKBR level, whereas the cell-based assay analyzed arrestin recruitment. Biodistribution and SPECT imaging of the A431/CCKBR xenograft mouse model as well as histological analysis of the dissected tumors were used for in vivo validation. Results: Our screen identified the inhibitors of mammalian target of rapamycin complex 1 (mTORC1), which increased cell uptake of [177Lu]Lu-PP-F11N. Pharmacological mTORC1 inhibition by RAD001 and metformin increased internalization of [177Lu]Lu-PP-F11N in A431/CCKBR and in AR42J cells. Analysis of protein lysates from RAD001-treated cells revealed increased levels of CCKBR (2.2-fold) and inhibition of S6 phosphorylation. PP-F11N induced recruitment of ß-arrestin1/2 and ERK1/2 phosphorylation. In A431/CCKBR-tumor bearing nude mice, 3 or 5 days of RAD001 pretreatment significantly enhanced tumor-specific uptake of [177Lu]Lu-PP-F11N (ratio [RAD001/Control] of 1.56 or 1.79, respectively), whereas metformin treatment did not show a significant difference. Quantification of SPECT/CT images confirmed higher uptake of [177Lu]Lu-PP-F11N in RAD001-treated tumors with ratios [RAD001/Control] of average and maximum concentration reaching 3.11 and 3.17, respectively. HE staining and IHC of RAD001-treated tumors showed a significant increase in necrosis (1.4% control vs.10.6% of necrotic area) and the reduction of proliferative (80% control vs. 61% of Ki67 positive cells) and mitotically active cells (1.08% control vs. 0.75% of mitotic figures). No significant difference in the tumor vascularization was observed after five-day RAD001 or metformin treatment. Conclusions: Our data demonstrates, that increased CCKBR protein level by RAD001 pretreatment has the potential to improve tumor uptake of [177Lu]Lu-PP-F11N and provides proof-of-concept for the development of molecular strategies aimed at enhancing the level of the targeted receptor, to increase the efficacy of PRRT and nuclear imaging.

Design of Radiolabeled Analogs of Minigastrin by Multiple Amide-to-Triazole Substitutions.

The insertion of single 1,4-disubstituted 1,2,3-triazoles as metabolically stable bioisosteres of trans-amide bonds (triazole scan) was recently applied to the 177Lu-labeled tumor-targeting analog of minigastrin, [Nle15]MG11. The reported novel mono-triazolo-peptidomimetics of [Nle15]MG11 showed either improved resistance against enzymatic degradation or a significantly increased affinity toward the target receptor but never both. To enhance further the tumor-targeting properties of the minigastrin analogs, we studied conjugates with multiple amide-to-triazole substitutions for additive or synergistic effects. Promising candidates were identified by modification of two or three amide bonds, which yielded both improved stability and increased receptor affinity of the peptidomimetics in vitro. Biodistribution studies of radiolabeled multi-triazolo-peptidomimetics in mice bearing receptor-positive tumor xenografts revealed up to 4-fold increased tumor uptake in comparison to the all-amide reference compound [Nle15]MG11. In addition, we report here for the first time a linear peptidomimetic with three triazole insertions in its backbone and maintained biological activity.

Triazolo-Peptidomimetics: Novel Radiolabeled Minigastrin Analogs for Improved Tumor Targeting.

MG11 is a truncated analog of minigastrin, a peptide with high affinity and specificity toward the cholecystokinin-2 receptor (CCK2R), which is overexpressed by different tumors. Thus, radiolabeled MG11 derivatives have great potential for use in cancer diagnosis and therapy. A drawback of MG11 is its fast degradation by proteases, leading to moderate tumor uptake in vivo. We introduced 1,4-disubstituted 1,2,3-triazoles as metabolically stable bioisosteres to replace labile amide bonds of the peptide. The "triazole scan" yielded peptidomimetics with improved resistance to enzymatic degradation and/or enhanced affinity toward the CCK2R. Remarkably, our lead compound achieved a 10-fold increase in receptor affinity, resulting in a 2.6-fold improved tumor uptake in vivo. Modeling of the ligand-CCK2R complex suggests that an additional cation-π interaction of the aromatic triazole moiety with the Arg356 residue of the receptor is accountable for these observations. We show for the first time that the amide-to-triazole substitution strategy offers new opportunities in drug development that go beyond the metabolic stabilization of bioactive peptides.

Gastrin, Cholecystokinin, Signaling, and Biological Activities in Cellular Processes.

The structurally-related peptides, gastrin and cholecystokinin (CCK), were originally discovered as humoral stimulants of gastric acid secretion and pancreatic enzyme release, respectively. With the aid of methodological advances in biochemistry, immunochemistry, and molecular biology in the past several decades, our concept of gastrin and CCK as simple gastrointestinal hormones has changed considerably. Extensive in vitro and in vivo studies have shown that gastrin and CCK play important roles in several cellular processes including maintenance of gastric mucosa and pancreatic islet integrity, neurogenesis, and neoplastic transformation. Indeed, gastrin and CCK, as well as their receptors, are expressed in a variety of tumor cell lines, animal models, and human samples, and might contribute to certain carcinogenesis. In this review, we will briefly introduce the gastrin and CCK system and highlight the effects of gastrin and CCK in the regulation of cell proliferation and apoptosis in both normal and abnormal conditions. The potential imaging and therapeutic use of these peptides and their derivatives are also summarized.

CCK-1 and CCK-2 receptor agonism do not stimulate GLP-1 and neurotensin secretion in the isolated perfused rat small intestine or GLP-1 and PYY secretion in the rat colon.

Gastrin and cholecystokinin (CCK) are hormones released from endocrine cells in the antral stomach (gastrin), the duodenum, and the jejunum (CCK). Recent reports, based on secretion experiments in an enteroendocrine cell line (NCI-H716) and gastrin receptor expression in proglucagon-expressing cells from the rat colon, suggested that gastrin could be a regulator of glucagon-like peptide-1 (GLP-1) secretion. To investigate these findings, we studied the acute effects of CCK-8 (a CCK1/CCK2 (gastrin) receptor agonist) and gastrin-17 (a CCK2(gastrin) receptor agonist) in robust ex vivo models: the isolated perfused rat small intestine and the isolated perfused rat colon. Small intestines from Wistar rats (n = 6), were perfused intraarterially over 80 min. During the perfusion, CCK (1 nmol/L) and gastrin (1 nmol/L) were infused over 10-min periods separated by washout/baseline periods. Colons from Wistar rats (n = 6) were perfused intraarterially over 100 min. During the perfusion, CCK (1 nmol/L), vasoactive intestinal peptide (VIP) (10 nmol/L), and glucose-dependent insulinotropic polypeptide (GIP) (1 nmol/L) were infused over 10-min periods separated by washout/baseline periods. In the perfused rat small intestines neither CCK nor gastrin stimulated the release of GLP-1 or neurotensin. In the perfused rat colon, neither CCK or VIP stimulated GLP-1 or peptide YY (PYY) release, but GIP stimulated both GLP-1 and PYY release. In both sets of experiments, bombesin, a gastrin-releasing peptide analog, served as a positive control. Our findings do not support the suggestion that gastrin or CCK participate in the acute regulation of intestinal GLP-1 secretion, but that GIP may play a role in the regulation of hormone secretion from the colon.

Antidiabetic effects and sustained metabolic benefits of sub-chronic co-administration of exendin-4/gastrin and xenin-8-Gln in high fat fed mice.

The present study has examined the antidiabetic effects of 21 days co-administration of xenin-8-Gln with the dual-acting fusion peptide, exendin-4/gastrin, as well as persistence of beneficial metabolic benefits, in high fat fed (HFF) mice. Xenin-8-Gln, exendin-4 and gastrin represent compounds that activate receptors of the gut-derived hormones, xenin, glucagon-like peptide-1 (GLP-1) and gastrin, respectively. Twice-daily administration of exendin-4/gastrin, xenin-8-Gln or a combination of both peptides significantly reduced circulating glucose, HbA1c and cumulative energy intake. Combination therapy with xenin-8-Gln and exendin-4/gastrin increased circulating insulin. All HFF mice treated with exendin-4/gastrin presented with body weight similar to lean control mice on day 21. Each treatment improved glucose tolerance and the glucose-lowering actions of glucose dependent insulinotropic polypeptide (GIP), as well as augmenting glucose- and GIP-induced insulin secretion, with benefits being most prominent in the combination group. Administration of exendin-4/gastrin alone, and in combination with xenin-8-Gln, increased pancreatic insulin content and improved the insulin sensitivity index. Pancreatic beta-cell area was significantly increased, and alpha cell area decreased, by all treatments, with the combination group also displaying enhanced overall islet area. Notably, metabolic benefits were generally retained in all groups of HFF mice, and especially in the combination group, following discontinuation of the treatment regimens for 21 days. This was associated with maintenance of increased islet and beta-cell areas. Together, these data confirm the antidiabetic effects of co-activation of GLP-1, gastrin and xenin cell signalling pathways, and highlight the sustainable benefits this type of treatment paradigm can offer in T2DM.

Islets from human donors with higher but not lower hemoglobin A1c levels respond to gastrin treatment in vitro.

Gastrin is a peptide hormone, which in combination with other factors such as TGFα, EGF or GLP-1, is capable of increasing beta cell mass and lowering blood glucose levels in adult diabetic mice. In humans, administration of a bolus of gastrin alone induces insulin secretion suggesting that gastrin may target islet cells. However, whether gastrin alone is sufficient to exert an effect on isolated human islets has been controversial and the mechanism remained poorly understood. Therefore, in this study we started to examine the effects of gastrin alone on cultured adult human islets. Treatment of isolated human islets with gastrin I for 48 h resulted in increased expression of insulin, glucagon and somatostatin transcripts. These increases were significantly correlated with the levels of donor hemoglobin A1c (HbA1c) but not BMI or age. In addition, gastrin treatment resulted in increased expression of PDX1, NKX6.1, NKX2.2, MNX1 and HHEX in islets from donors with HbA1c greater than 42 mmol/mol. The addition of YM022, an antagonist of the gastrin receptor cholecystokinin B receptor (CCKBR), together with gastrin eliminated these effects, verifying that the effects of gastrin are mediated through CCKBR.CCKBR is expressed in somatostatin-expressing delta cells in islets from all donors. However, in the islets from donors with higher HbA1c (greater than 42 mmol/mol [6.0%]), cells triple-positive for CCKBR, somatostatin and insulin were detected, suggesting a de-differentiation or trans-differentiation of endocrine cells. Our results demonstrate a direct effect of gastrin on human islets from prediabetic or diabetic individuals that is mediated through CCKBR+ cells. Further, our data imply that gastrin may be a potential treatment for diabetic patients.

Gastrin promotes angiogenesis by activating HIF-1α/ß-catenin/VEGF signaling in gastric cancer.

Angiogenesis is recognized as a sign of cancer and facilitates cancer progression and metastasis. Suppression of angiogenesis is a desirable strategy for gastric cancer (GC) management. In this study, we showed a novel role of gastrin in angiogenesis of GC. We observed that treatment with gastrin 17 (G17) increased the proliferation of AGS cells and enhanced tube formation during normoxia and hypoxia. The expression level of VEGF were increased by G17 treatment as well. Experiments on the mechanism showed that G17 promoted HIF-1α expression, which subsequently enhanced ß-catenin nuclear localization and activation of TCF3 and LEF1 and finally resulted in angiogenesis by upregulating VEGF. An in vivo experiment confirmed that G17 enhanced GC cell proliferation and angiogenesis in the resultant tumor. In conclusion, our findings indicate that gastrin promotes angiogenesis via activating HIF-1α/ß-catenin/VEGF axis in GC.

Notoginsenoside R1 (NGR1) Attenuates Chronic Atrophic Gastritis in Rats.

BACKGROUND This study investigated the effect and mechanism of notoginsenoside R1 (NGR1) on chronic atrophic gastritis (CAG) in a rat model. MATERIAL AND METHODS To perform our investigation, a rat model of CAG was established, and then rats were treated with various doses of NGR1. After treatment, hematoxylin-eosin (HE) staining was used for histopathological observation and further scoring. Enzyme-linked immunosorbent assay (ELISA) was used to determine the contents of gastrointestinal hormones, inflammatory factors, gastric mucosal destruction factors, and gastric mucosal-protective factors. Gene and protein expressions were measured using quantitative real-time PCR and Western blot assay, respectively. RESULTS Results indicated that NGR1 relieved rat CAG. NGR1 treatment significantly increased the levels of gastrin (GAS) and somatostatin (SS) and reduced motilin (MTL) in the serum of CAG rats. The serum levels of interleukin (IL)-1ß and IL-6 were significantly reduced by NGR1 treatment in CAG rats in a dose-dependent manner. Additionally, the increased levels of prostaglandin (PG)E2, nitric oxide synthase (NOS), and endothelin (ET) in CAG rats were significantly decreased by NGR1 administration. Moreover, the decreased level of secretory IgA (sIgA) and glutathione (GSH) in rats caused by MNNG was notably increased by NGR1 treatment. No significant changes were found in glutathione disulfide (GSSG) secretion. Finally, we found that the increased Bcl-2 expression and reduced Bax expression in the stomach tissues of rats caused by MNNG were eliminated by NGR1 treatment. CONCLUSIONS NGR1 exerts a protective effect on CAG, and it is a multi-target, multi-linked, comprehensive process.