胃泌素及胃泌素释放肽在胃癌组织中的表达及意义

目的 研究胃癌组织中胃泌素（Gastyin，GAS）、胃泌素释放肽（Gastrin releasing peptide，GRP）的表达及其意义。方法采用组织芯片技术制作60例胃癌组织芯片，同时用S—P免疫组织化学方法检测胃癌组织芯片中GAS、GRP的表达。结果 60例胃癌中GAS阳性率为31．7％；GRP阳性率为11．7%。中、低分化胃癌GAS、GRP的表达阳性率高于高分化胃癌（P〈0．05），黏液腺癌、印戒细胞癌GAS、GRP的表达阳性率显著高于其它组织学类型胃癌（P〈0．01），胃癌GAS、GRP阳性表达与淋巴结转移相关（P〈0.05）。结论 本研究结果提示中、低分化胃癌，黏液腺癌、印戒细胞癌可作为胃癌内分泌治疗的主要适应证。     

胃泌素释放肽前体的研究进展及其临床意义

胃泌素释放肽前体(ProGRP)是一种最近发现的小细胞肺癌(SCLC)的特异性的肿瘤标志物.国内外大量研究发现ProGRP在正常个体的血清水平大都在正常范围,仅在少量的良性疾病患者中超过正常上限,这主要集中在肾功能不全患者.在恶性肿瘤中,血ProGRP水平增高主要集中在神经内分泌肿瘤及肺癌,尤其SCLC.ProGRP对SCLC的敏感度和特异性分别高达79.7%和95%,较神经元特异性烯醇化酶更能准确监测疾病过程和预测肿瘤复发,但神经元特异性烯醇化酶较ProGRP能更好地预示化疗效果.两者具有互补性,联合检测将使SCLC的诊断、预后和监测复发更加准确.     

胃泌素受体作为分子靶向在肿瘤中的表达及应用

胃泌素(Gas)广泛存在于胃肠道和胰腺组织内,在调控生理功能及某些疾病的发病机制中都有重要作用.近来研究表明,Gas能够促进肿瘤尤其是胃癌、大肠癌等消化系肿瘤的发生、发展.Gas的生物作用主要通过CCK受体介导,Gas mRNA在一些CCK受体阳性的小细胞肺癌,乳腺癌,卵巢癌,不同来源的癌干细胞,已经发现有表达,可能作为这些肿瘤自分泌生长调节的指示指标.对于过表达胃泌素受体的肿瘤,可以给予胃泌素多肽及类似物作放射性标记或连接细胞毒药物,体内用闪烁成像法跟踪显像,从而用于肿瘤的诊断和治疗.     

胃泌素释放肽受体拮抗剂RC-3095对大鼠肺组织纤维化的干预作用

目的研究胃泌素释放肽(GRP)受体(R)拮抗剂RC-3095对大鼠肺组织纤维化的干预作用。方法构建肺组织纤维化大鼠模型,将大鼠随机分为正常对照组(NC组)、模型组(MO组)、RC-3095处理组(RC组,20μg/d),检测肺湿重、肺干重、肺系数,HE染色观察肺组织病理变化,酶联免疫吸附法检测肺组织中Ⅰ型和Ⅲ型胶原含量,Western印迹检测GRP、GRPR和转化生长因子(TGF)β1蛋白表达情况,免疫共沉淀检测GRP和GRPR相互作用情况。结果成功构建肺组织纤维化大鼠模型,MO组肺组织结构被破坏,肺泡间隔增厚,存在大量炎性细胞浸润;RC组肺组织结构较为完整,纤维化程度降低。同时MO组肺组织湿重、干重和肺系数均高于NC组,RC组肺组织湿重、干重和肺系数均高于NC组但是低于MO组(P0.05)。MO组中Ⅰ型胶原含量高于NC组,Ⅲ型胶原含量低于NC组。RC组中Ⅰ型胶原含量低于MO组,Ⅲ型胶原含量高于MO组(P0.05)。RC-3095处理可有效抑制GRPR和TGFβ1蛋白水平,同时抑制GRPR和GPR的结合。结论 RC-3095可以通过调节GRP和GRPR的结合能力及TGFβ1的蛋白水平有效地抑制肺部纤维化。     

胃泌素和结肠肿瘤

近年来胃泌素与结肠肿瘤的研究取得了很大突破。其中,胃泌素前体的作用和不同于CCK－A、CCK－B的新受体存在已得到公认。进一步的研究已开始探讨胃泌素的作用方式;并研制新的胃泌素受体拮抗剂。本重点介绍这些新成就。     

胃泌素和结肠肿瘤

近年来胃泌素与结肠肿瘤的研究取得了很大突破。其中,胃泌素前体的作用和不同于CCK-A、CCK-B的新受体存在已得到公认。进一步的研究已开始探讨胃泌素的作用方式;并研制新的胃泌素受体拮抗剂。本文重点介绍这些新成就。     

胃泌素释放肽前体对小细胞肺癌诊断作用的初探

胃泌素释放肽 (ＧＲＰ)是脑肠激素的一种。肺癌与ＧＲＰ的关系是 1978年在人胚胎肺的内分泌细胞中发现蛙皮素(ｂｏｍｂｅｓｉｎ)样免疫活性之后开始认识的[1] 。其后的研究表明 ,ＧＲＰ是小细胞肺癌 (ＳＣＬＣ)的重要产物 ,血ＧＲＰ水平是ＳＣＬＣ重要的标志物[2 ] ,但其测定方法繁琐 ,难以普及。研究表明 ,测定胃泌素释放肽前体 (ＰｒｏＧＲＰ)作为ＳＣＬＣ标志物是完全可行的[3 ,4 ] 。ＰｒｏＧＲＰ因部分氨基酸残基的不同 ,存在 3种分子型。利用针对 3种分子的共同序列 ,即ＰｒｏＧＲＰ(31 98)的酶免疫分析药盒 ,测定了 16 2例血清标本 ,…     

胃泌素及其受体与胃癌关系研究进展

多数研究认为 ,某些胃癌组织或细胞株有胃泌素及其受体基因表达 ,胃泌素通过受体介导的细胞内信号传导途径促进胃癌的发生与生长 ;胃癌患者血浆、胃液中胃泌素水平升高对预后判断可能有一定临床参考价值 ,胃泌素及其受体拮抗剂将为胃癌内分泌治疗开辟新的途径。     

甘氨酸延伸型胃泌素受体在结肠和结直肠肿瘤中的研究

目的建立甘氨酸延伸型胃泌素胞浆膜受体结合试验,并应用该方法检测甘氨酸延伸型胃泌素受体的部分特性及其在正常结肠和人结直肠肿瘤中的表达.方法用人结直肠肿瘤细胞株DLD-1建立胞浆膜制备方法,125I标记的甘氨酸延伸型胃泌素进行受体结合试验.结果胞浆膜受体结合试验的条件为5～10mg胞浆膜(离心25000r/min45min制备),37℃温育60min.正常Sprague-Dawley大鼠结肠粘膜和从结肠粘膜制备的胞浆膜有特异结合,而从完整结肠制备的胞浆膜无特异结合.胞浆膜甘氨酸延伸型胃泌素受体抑制50%结合的非标记配体浓度(IC50)为3.64μmol/L±1.93μmol/L;特异性胆囊收缩素(CCK)-A受体拮抗剂L364和特异性CCK-B受体拮抗剂L365不能拮抗该受体;非特异性受体拮抗剂氯苯酰色氨酸则能拮抗.结论甘氨酸延伸型胃泌素受体位于正常大鼠结肠粘膜、结肠粘膜和结直肠肿瘤细胞膜上,属单结合位点、低亲和力受体,不能被特异性CCK-A或CCK-B受体拮抗剂拮抗,是一种新受体.     

葡萄糖依赖性促胰岛素释放肽-受体信号通路与肥胖症的研究进展

葡萄糖依赖性促胰岛素释放肽（GIP）是一种由小肠黏膜上皮K细胞合成并分泌的肠促胰岛素分泌肽,能够刺激胰岛素和胰高糖素的分泌。近年来研究发现,GIP-GIP受体（GIPR）信号通路在肥胖症及其相关代谢异常中起到重要作用。GIP和GIPR基因的多态性与肥胖易感性显著相关。激活GIP-GIPR通路能增加脂肪合成和储存,促进肥...     

Islet function phenotype in gastrin-releasing peptide receptor gene-deficient mice

Gastrin-releasing peptide (GRP) is an islet neuropeptide that stimulates insulin secretion. To explore whether islet GRP contributes to neurally mediated insulin secretion, we studied GRP receptor (GRPR)-deleted mice. By using RT-PCR we showed that GRPR mRNA is expressed in islets of wild-type mice, but is lost in GRPR-deleted mice. Functional studies revealed that GRP potentiates glucose-stimulated insulin secretion in wild-type animals, but not in GRPR-deleted mice. This shows that GRPR is the receptor subtype mediating GRP-induced insulin secretion and that GRPR-deleted mice are tools for studying the physiological role of islet GRP. We found that GRPR-deleted mice display 1) augmentation of the insulin response to glucose by a mechanism inhibited by ganglionic blockade; 2) increased insulin responsiveness also to the cholinergic agonist carbachol, but not to arginine; 3) impaired insulin and glucagon responses to autonomic nerve activation by 2-deoxyglucose; 4) normal islet adaptation to high fat-induced insulin resistance and fasting; and 5) normal islet cytoarchitecture, as revealed by immunocytochemistry of insulin and glucagon. In conclusion, 1) GRPR is the receptor subtype mediating the islet effects of GRP; 2) GRP contributes to insulin secretion induced by activation of the autonomic nerves; and 3) deletion of GRPR is compensated by increased cholinergic sensitivity.     

Progastrin-releasing peptide and gastrin-releasing peptide receptor mRNA expression in non-tumor tissues of the human gastrointestinal tract

AIM: To investigate the expression of gastrin-releasing peptide (GRP) and GRP-receptor mRNA in non-tumor tissues of the human esophagus, gastrointestinal tract, pancreas and gallbladder using molecular biology techniques. METHODS: Poly A mRNA was isolated from total RNA extracts using an automated nucleic acid extractor and, subsequently, converted into single-stranded cDNA (sscDNA). PCR amplifications were carried out using genespecific GRP and GRP-receptor primers. The specificity of the PCR amplicons was further confirmed by Southern blot analyses using gene-specific GRP and GRP-receptor hybridization probes. RESULTS: Expression of GRP and GRP-receptor mRNA was detected at various levels in nearly all segments of the non-tumor specimens analysed, except the gallbladder. In most of the biopsy specimens, coexpression of both GRP and GRP-receptor mRNA appeared to take place. However, expression of GRP mRNA was more prominent than was GRP-receptor mRNA. CONCLUSION: GRP and GRP-receptor mRNAs are expressed throughout the gastrointestinal tract and provides information for the future mapping and determination of its physiological importance in normal and tumor cells.     

Disruptions in feeding and body weight control in gastrin-releasing peptide receptor deficient mice

Bombesin (BN) interacts with two mammalian receptor subtypes termed gastrin-releasing peptide (GRP)-preferring (GRP-R) and neuromedin B (NMB)-preferring (NMB-R) that may mediate the satiety action of BN. We examined the feeding behavior of mice that were deficient in the GRP-R (GRP-R KO) to assess the overall contribution of this receptor subtype in the feeding actions of BN-related peptides. GRP-R KO mice failed to suppress glucose intake in response to systemically administered BN and GRP(18-27), whereas both peptides elicited a potent reduction of intake in wild-type (WT) mice. Neither GRP-R KO nor WT mice suppressed glucose intake following NMB administration. Unlike the impaired responses to BN-like peptides, the feeding inhibitory action of cholecystokinin was enhanced in GRP-R KO mice. Consistent with behavioral results, GRP-R KO mice also exhibited a reduction in c-Fos immunoreactivity in the nucleus of the solitary tract (NTS) and paraventricular nucleus (PVN) following peripheral administration of BN. An evaluation of meal patterns showed that GRP-R KO mice ate significantly more at each meal than WT mice, although total 24 h food consumption was equivalent. A long-term analysis of body weight revealed a significant elevation in GRP-R KO mice compared with WT littermates beginning at 45 weeks of age. These data suggest that the GRP-R mediates the feeding effects of BN-like peptides and participates in the termination of meals in mice.     

Estrogens influence female itch sensitivity via the spinal gastrin-releasing peptide receptor neurons

There are sex differences in somatosensory sensitivity. Circulating estrogens appear to have a pronociceptive effect that explains why females are reported to be more sensitive to pain than males. Although itch symptoms develop during pregnancy in many women, the underlying mechanism of female-specific pruritus is unknown. Here, we demonstrate that estradiol, but not progesterone, enhances histamine-evoked scratching behavior indicative of itch in female rats. Estradiol increased the expression of the spinal itch mediator, gastrin-releasing peptide (GRP), and increased the histamine-evoked activity of itch-processing neurons that express the GRP receptor (GRPR) in the spinal dorsal horn. The enhancement of itch behavior by estradiol was suppressed by intrathecal administration of a GRPR blocker. In vivo electrophysiological analysis showed that estradiol increased the histamine-evoked firing frequency and prolonged the response of spinal GRP-sensitive neurons in female rats. On the other hand, estradiol did not affect the threshold of noxious thermal pain and decreased touch sensitivity, indicating that estradiol separately affects itch, pain, and touch modalities. Thus, estrogens selectively enhance histamine-evoked itch in females via the spinal GRP/GRPR system. This may explain why itch sensation varies with estrogen levels and provides a basis for treating itch in females by targeting GRPR.

Itch and pain warn the body of potential tissue damage and are indispensable to survival. The threshold and intensity of itch and pain are not absolute but depend on various environmental and psychological factors such as stress, mood, and anxiety (1–3). Female-specific pruritus occurs during pregnancy and menopause when circulating female hormones dramatically fluctuate (4, 5). Approximately 20% of pregnant women have itch symptoms during pregnancy (6), such as pruritic urticarial papules and plaques of pregnancy, intrahepatic cholestasis of pregnancy, and pemphigoid gestationis. Female patients with atopic dermatitis often experience atopic eruption and cutaneous deterioration associated with their pregnancy (7–9). Although these itch symptoms impair female quality of life, the mechanism is still unknown. Histamine is an important peripheral itch mediator. Once released from mast cells activated by irritant stimuli and allergens, histamine induces not only inflammation but also itch triggered by the excitation of a subset of unmyelinated C fibers (10). Centrally, neurons expressing the gastrin-releasing peptide (GRP) and its receptor (GRPR) play a critical role in the spinal cord transmission of itch signals independent of pain (11–15). In the present study, we focused on the female sex hormones as candidates for the cause of itch in women. We discovered that female itch sensitivity is induced by estrogens via the spinal GRP/GRPR system in rats.     

Immunoreactive gastrin-releasing peptide in medullary thyroid carcinoma

We have previously shown that immunoassayable concentration of somatostatin (SRIH) was elevated in 70% of 34 consecutive medullary thyroid carcinoma (MTC) tissue samples. In the present study gastrin releasing peptide (GRP)-like immunoreactivity was measured in tissue extracts from these 34 MTC (25 inherited, 7 sporadic, 2 unclassified) and in 7 normal thyroid tissue. Plasma SRIH, calcitonin (CT) and carcinoembryonic antigen were assayed in all patients. Normal thyroid tissue contained less than 61 pmol GRP per g wet weight; in contrast GRP concentration was elevated (62-7800 pmol/g) in 32/34 tumor extracts. The distribution of tissue GRP values were similar in sporadic as well as in familial MTC. We found no significant correlation between tumor GRP concentration and plasma SRIH (r = -0.05), plasma CT (r = -0.24), or plasma carcinoembryonic antigen levels (r = -0.21). Tumor concentrations of immunoreactive GRP and SRIH were positively correlated when logarithmic transformation was used (P less than 0.01). Thus GRP, as well as SRIH, is a major product of tumoral C cells in human MTC when systematically evaluated in a large number of cases.     

C-terminal fragments of the gastrin-releasing peptide precursor stimulate cell proliferation via a novel receptor

There are many precedents for the production from a single precursor of multiple peptides, with independent receptors and different bioactivities. Gastrin-releasing peptide (GRP) is initially synthesized as amino acids 1-27 of a 125-residue precursor, proGRP, and is subsequently cleaved and amidated to form GRP18-27. We investigated the hypothesis that C-terminal proGRP peptides are also biologically active. Human proGRP18-125 was expressed in Escherichia coli as a glutathione S-transferase fusion protein. Recombinant proGRP18-125 stimulated proliferation and migration of the human colorectal carcinoma cell line DLD-1. The observations that an antagonist selective for the GRP receptor did not inhibit activity in either proliferation or migration assays and that the recombinant peptide did not bind to either the GRP receptor or orphan receptor BRS-3 indicated that neither activity was mediated by the known GRP receptors. Recombinant human proGRP31-125 and proGRP42-98 were also prepared and shown to stimulate proliferation of DLD-1 cells and the human prostate carcinoma cell line DU145. The synthetic peptides proGRP47-68 and [Tyr79]proGRP80-97 stimulated inositol phosphate production, MAPK kinase activity, and proliferation and migration of DLD-1 cells. Binding sites for both radioiodinated synthetic peptides were demonstrated on DLD-1 cells. Each peptide was able to compete with the other for binding, and a GRP receptor antagonist did not inhibit binding of either peptide. We conclude that peptides derived from the C terminus of proGRP are biologically active and that their activity is mediated by a receptor distinct from the two known GRP receptors.     

Corticotropin-releasing activity of gastrin-releasing peptide in normal men

Gastrin-releasing peptide (GRP; mammalian bombesin) exerts several functions within the hypothalamus and is a putative regulator of pituitary hormone secretion. We investigated the effect of GRP on the secretion of pituitary hormones and cortisol in normal men. GRP was infused iv as primed infusions of 0.12 pmol/kg BW. min for 30 min (GRP I) and 1.50 pmol/kg. min for an additional 30 min (GRP II). GRP dose-dependently stimulated ACTH secretion compared with the effect of saline [net change in ACTH (delta ACTH) before and after treatment: GRP I, 3 +/- 1 (+/- SEM) vs. 0 +/- 1 pmol/L (P less than 0.05); GRP II, 5 +/- 1 vs. -3 +/- 1 pmol/L; P less than 0.01)]. A further increase in plasma ACTH concentration occurred after cessation of GRP infusion (7 +/- 2 vs. 0 +/- 1 pmol/L; P less than 0.025). GRP caused a similar dose-dependent stimulation of cortisol secretion compared with the effect of saline [delta cortisol before and after treatment: GRP I, -19 +/- 21 vs. -68 +/- 14 nmol/L (P less than 0.05); GRP II, 38 +/- 33 vs. -86 +/- 15 nmol/L (P less than 0.005)]. The serum cortisol concentration increased further after cessation of the GRP infusion (72 +/- 31 vs. -124 +/- 33 nmol/L; P less than 0.0025). GRP dose-dependently stimulated beta-endorphin immunoreactivity compared with the effect of saline [delta beta-endorphin immunoreactivity before and after treatment: GRP I, 6 +/- 1 vs. -3 +/- 1 pmol/L (P less than 0.01); GRP II, 11 +/- 4 vs. -6 +/- 2 pg/mL (P less than 0.025)]. GRP had no effect on PRL or GH secretion. We suggest that GRP participates in the neuroendocrine regulation of the secretion of proopiomelanocortin-derived peptides.     

Phosphorylation of TNF-alpha converting enzyme by gastrin-releasing peptide induces amphiregulin release and EGF receptor activation

G protein-coupled receptors induce EGF receptor (EGFR) signaling, leading to the proliferation and invasion of cancer cells. Elucidation of the mechanism of EGFR activation by G protein-coupled receptors may identify new signaling paradigms. A gastrin-releasing peptide (GRP)/GRP receptor-mediated autocrine pathway was previously described in squamous cell carcinoma of head and neck. In the present study, we demonstrate that TNF-alpha converting enzyme (TACE), a disintegrin and metalloproteinse-17, undergoes a Src-dependent phosphorylation that regulates release of the EGFR ligand amphiregulin upon GRP treatment. Further investigation reveals the phosphatidylinositol 3-kinase (PI3-K) as the intermediate of c-Src and TACE, contributing to their association and TACE phosphorylation. Phosphoinositide-dependent kinase 1 (PDK1), a downstream target of PI3-K, has been identified as the previously undescribed kinase to directly phosphorylate TACE upon GRP treatment. These findings suggest a signaling cascade of GRP-Src-PI3-K-PDK1-TACE-amphiregulin-EGFR with multiple points of interaction, translocation, and phosphorylation. Furthermore, knockdown of PDK1 augmented the antitumor effects of the EGFR inhibitor erlotinib, indicating PDK1 as a therapeutic target to improve the clinical response to EGFR inhibitors.