Bombesin-like immunoreactivity in the lung

Pro-gastrin-releasing peptide (31-98) as a tumour marker of small-cell lung cancer: comparative evaluation with neuron-specific enolase

We attempted to clarify whether serum levels of a carboxy-terminal fragment of ProGRP, ProGRP(31-98), could serve as a more accurate tumour marker in patients with SCLC than neuron-specific enolase (NSE). ProGRP(31-98) and NSE were measured retrospectively in 101 newly diagnosed untreated patients with SCLC, 111 with non-small-cell lung cancer (NSCLC) and 114 patients with non-malignant lung diseases. ProGRP(31-98) and NSE levels were determined using a sandwich enzyme-linked immunosorbent assay. Sensitivity in SCLC patients was 72.3% for ProGRP(31-98) and 62.4% for NSE. Comparing the area under curve (AUC) of 'receiver operator characteristics' of ProGRP(31-98) with that of NSE, ProGRP(31-98) was the more powerful marker in the diagnosis of SCLC (P = 0.0001). Serum levels of ProGRP(31-98) were higher in the 40 patients with extensive disease than in the 61 patients with limited disease (P = 0.0082). ProGRP(31-98) was significantly higher in patients with pure small-cell carcinoma than in patients with mixed small-cell/large-cell carcinoma (P = 0.02). In serial measurement in 16 patients responding to treatment, a high degree of correlation was noted between the decrease in serum ProGRP(31-98) levels and clinical response during the second week after treatment (P = 0.0045). These results indicate that the determination of serum ProGRP(31-98) levels plays an important role in the diagnosis and treatment of SCLC patients.

There are three distinct forms of bombesin. Identification of [Leu13]bombesin, [Phe13]bombesin, and [Ser3,Arg10,Phe13]bombesin in the frog Bombina orientalis

Amphibian bombesin is the prototypic peptide that defines the bombesin-like peptide family. In this paper we show that in the frog Bombina orientalis, there are actually 3 distinct forms of bombesin, and each of these peptides is an agonist with differing affinities for the known bombesin receptors. Oligonucleotides complementary to the 5'- and 3'-untranslated regions of the bombesin mRNA were used to amplify bombesin-related cDNAs from the skin, brain, and gut of B. orientalis. Three classes of cDNAs were found. One class encoded the previously characterized form of bombesin which has a Leu at position 13 ([Leu13]bombesin). The other two classes, respectively, encoded new bombesin-like peptides which we have designated as [Phe13]bombesin and [Ser3,Arg10,Phe13]bombesin ([SAP]bombesin). The existence of [SAP]bombesin in skin was confirmed by tandem mass spectrometry. Polymerase chain reaction analysis of genomic DNA showed the mRNAs for [Leu13]bombesin, [Phe13]bombesin, and [SAP]bombesin most likely arise from separate genes. Polymerase chain reaction analysis showed different patterns of tissue-specific expression for each form. [Leu13]Bombesin and [SAP]bombesin were predominantly expressed in skin, brain, and gut; [Phe13]bombesin was expressed only in brain, and [Leu13]bombesin predominated in oocytes. [SAP]Bombesin contained a cleavage site between residues 4 and 5, which if used would yield the peptide [SAP]bombesin(5-14) which has the sequence [Gln3,Arg6]neuromedin B. Thus a frog homolog of NMB could derive from the [SAP]bombesin prohormone. [Phe13]Bombesin, [SAP]bombesin, and [SAP]bombesin(5-14) were synthesized and their affinities for the mammalian bombesin-like peptide (GRP and NMB) receptors determined. These peptides acted as agonists for the GRP and NMB receptors, with relative potencies for the GRP receptor of [Leu13]bombesin > [Phe13]bombesin > [SAP]bombesin(5-14) > [SAP]bombesin and for the NMB receptor of [Phe13]bombesin > [SAP]bombesin(5-14) > [Leu13]bombesin > [SAP]bombesin. None of these peptides demonstrated high affinity binding for the BRS-3 receptor. The different receptor affinities and tissue distribution of these peptides suggests distinct physiologic roles and raises the possibility of as yet uncharacterized mammalian homologs of these new amphibian peptides.

Immunohistochemistry in diagnostic dermatopathology

Immunopathology continues to be important in diagnostic dermatopathology. Immunopathology is an invaluable tool for assessing the tissue of origin or direction of differentiation of cells. In some cases this can result in a more precise diagnosis. This article reviews the role of immunopathology in determining the biologic behavior of hematolymphoid infiltrates. It explores the methodology of immunoperoxidase, discusses the most commonly used antibody reagents, and presents a series of diagnostic dilemmas in which immunopathology can be useful. In each case a strategy is established that maximizes the likelihood of making a definitive diagnosis.

Pulmonary Neuroendocrine Cells and Lung Development

Pulmonary neuroendocrine cells produce bioactive peptides such as gastrin-releasing peptide (GRP) at high levels in developing fetal lung. The role of GRP and other peptides in promoting branching morphogenesis, cell proliferation, and cell differentiation during lung organogenesis is reviewed. Possible roles for bioactive peptides derived from these cells in the pathophysiology of perinatal lung disorders are discussed.

Calcitonin gene-related peptide (CGRP) in the developing mouse limb

The mitogenic effects of neuropeptides and their localization to developing tissues suggest an important role for these peptides during gestation. We examined the expression and action of the neuropeptide calcitonin gene-related peptide (CGRP) in the developing mouse limb bud, an excellent model system for studying musculoskeletal development. CGRP immunoreactivity (CGRP-ir) was detected in the developing limb at day 16.5 of gestation (E 16.5) and was limited to nerve fibers surrounding blood vessels, within the developing muscle or in close proximity to the developing cartilaginous skeleton. Although CGRP-ir was not observed until E 16.5, limb buds were responsive to CGRP as early as E 11.5. Within 5 min of exposure to CGRP (10(-8) to 10(-7) M) a 2--3-fold increase in cyclic AMP (cAMP) levels was observed. This CGRP-induced increase in cAMP was abolished by the addition of human CGRP8-37, a CGRP receptor antagonist. This result suggests that the effect on cAMP was mediated by the interaction of CGRP with CGRP receptors. Our findings indicate that mouse limbs are responsive to CGRP when they are composed of primarily undifferentiated mesenchyme and that CGRP-ir appears at a later stage of development in association with cartilage and muscle differentiation.

Hamster pulmonary endocrine cells with neural cell adhesion molecule (NCAM) immunostaining

Pulmonary endocrine cells of Syrian golden hamster were stained for neural cell adhesion molecule (NCAM) with indirect fluorescent immunostaining and observed with a confocal laser scanning microscope equipped with an argon laser. Sections 100 microns thick of hamster lung fixed with phosphate-buffered 4% paraformaldehyde were prepared. The sections were incubated with rat monoclonal antibody against NCAM, followed by fluorescence-labeled antibody against rat immunoglobulin. Some were doubly immunostained for NCAM and one of the following endocrine markers: neuron-specific enolase, calcitonin gene-related peptide and serotonin. Expression of NCAM in the hamster airway epithelium was seen in cell nests resembling neuroepithelial bodies (NEBs). NCAM immunostaining was positive at the lateral cell borders between the cells composing the nest, but negative at the border with the adjacent, presumably non-endocrine cells. Double immunostaining confirmed that the grouped cells with NCAM immunoreactivity were of an endocrine nature, but that single endocrine cells did not show NCAM immunoreactivity. An electron microscopic study with NCAM immunostaining confirmed the light microscopic study. These suggest that NCAM expression could be important for the morphogenesis of NEBs. A confocal laser microscope was used to make three-dimensional images of NEBs after NCAM immunostaining and the spatial interaction between NEBs and the surrounding microenvironment was studied.

Bombesin and [Leu8]phyllolitorin promote fetal mouse lung branching morphogenesis via a receptor-mediated mechanism

Pulmonary neuroendocrine cells are localized predominantly at airway branchpoints. Previous work showed that gastrin-releasing peptide (GRP), a major pulmonary bombesin-like peptide, occurred in neuroendocrine cells exclusively in branching human fetal airways. We now demonstrate that GRP and GRP receptor genes are expressed in fetal mouse lung as early as embryonic day 12 (E12), when lung buds are beginning to branch. By in situ hybridization, GRP receptor transcripts were at highest levels in mesenchymal cells at cleft regions of branching airways and blood vessels. To explore the possibility that bombesin-like peptides might play a role in branching morphogenesis, E12 lung buds were cultured for 48 hr in serum-free medium. In the presence of 0.10-10 microM bombesin, branching was significantly augmented as compared with control cultures, with a peak of 94% above control values at 1 microM (P < 0.005). The bombesin receptor antagonist [Leu13- psi(CH2NH)Leu14]bombesin alone (100 nM) had no effect on baseline branching but completely abolished bombesin-induced branching. A bombesin-related peptide, [Leu8]phyllolitorin also increased branching (65% above control values at 10 nM, P < 0.005). [Leu8]Phyllolitorin also significantly augmented thymidine incorporation in cultured lung buds. Fibronectin, which is abundant at branchpoints, induces GRP gene expression in undifferentiated cell lines. These observations suggest that BLPs secreted by pulmonary neuroendocrine cells may contribute to lung branching morphogenesis. Furthermore, components of branchpoints may induce pulmonary neuroendocrine cell differentiation as part of a positive feedback loop, which could account in part for the high prevalence of these cells at branchpoints.

Bombesin-like immunoreactivity in the rat larynx: increase in response to irradiation

It is previously well known that bombesin has effects as growth factor and that changes in bombesin content in air-way structures occur in various patho-physiological conditions. In the present study, the effects of radiotherapy on bombesin expression in the rat larynx were studied. Irradiation was given for five days, 6 or 8 gray daily. Ten days after cessation of irradiation, the subglottic part of the larynx from irradiated and control animals was dissected out, and processed for immunohistochemistry or radioimmunoassay. The radioimmunoassay analysis showed that the content of bombesin-like material increased 2-fold after irradiation. The immunohistochemical analysis displayed an increased bombesin-like immunoreactivity in local ganglionic cells and in nerve fibers in the submucosal glands. These nerve fibers are likely to be derived from the local ganglionic cells. On the other hand, there was no change in the pattern of immuno-reactivity in the innervation of the epithelium and the lamina propria, including the blood vessels. The observations show that radiotherapy can be added to the list of factors that influence bombesin expression in airway structures.

A 6-Mb YAC contig in Xp22.1-p22.2 spanning the DXS69E, XE59, GLRA2, PIGA, GRPR, CALB3, and PHKA2 genes

We report the generation of an approximately 6-Mb contig of 70 overlapping yeast artificial chromosomes (YAC) covering the interval between DXS16 and DXS1229 in Xp22.1-p22.2. Within this region lie the genes for calbindin (CALB3), gastrin-releasing peptide receptor (GRPR), phosphatidyl-inositol glycan-class A protein (PIGA), glycine receptor alpha-2 (GLRA2), phosphorylase kinase alpha (PHKA2), XE59 (a gene escaping X chromosome inactivation), and DXS69E (71-7A). YACs were isolated initially from four libraries either by hybridization or using sequence tagged sites (STSs) for DXS16, DXS9, GLRA2, DXS207, DXS43, DXS1416, DXS1317, DXS1195, and DXS418. Additional STSs were obtained from the end fragments of the original YACs studied, thus allowing us to cover the contig with a series of 73 STSs, approximately 1 per 100 kb. YAC contig construction allowed the following locus order to be established: Xpter-DXS16-DXS69E-DXS414-XE59 - DXS9 - (GLRA2, DXS987) - (PIGA, DXS207) - DXS1053-DXS197-(GRPR,DXS43)-CALB3-DXS14 16- DXS1317 - DXS1195 - DXS418 - DXS257 - (PHKA2, DXS999)-DXS443-DXS1229-Xcen. Restriction mapping of the DXS16-DXS43 interval predicted the existence of several CpG islands, suggesting the presence of other genes in the region. This work provides a starting point for further mapping and positional cloning of several X-linked disease genes.

Role of the lung in accumulation and metabolism of xenobiotic compounds--implications for chemically induced toxicity

The mammalian lung is exposed to and affected by many airborne and bloodborne foreign compounds. This review summarizes the role of lung in accumulation and metabolism of xenobiotics, some of which are spontaneously reactive or are metabolically activated to toxic intermediates. The specific architectural arrangement of mammalian lung favors that so-called pneumophilic drugs are filtered out of the blood and are retained within the tissue as shown in particular for amphetamine, chlorphentermine, amiodarone, imipramine, chlorpromazine, propranolol, local anaesthetics, and some miscellaneous therapeutics. There is strong evidence that intrapulmonary distribution activity and regulation of drug-metabolizing enzymes in lung is distinct from liver. This review focuses on the metabolic rate of selected compounds in lung such as 5-fluoro-2'-deoxyuridine, local anesthetics, nicotine, benzo(alpha)pyrene, ipomeanol, 4-methylnitrosamino-1-(3-pyridyl)-1-butanone. It is widely accepted that the formation of radical species is a key event in the pneumotoxic mechanisms induced by bleomycin, paraquat, 3-methylindole, butylhydroxytoluene, or nitrofurantoin. Finally, methodological approaches to assess the capacity of lung to eliminate foreign compounds as well as biochemical features of the pulmonary tissue are evaluated briefly.

7B2 expression in intrapulmonary neuroepithelial bodies: immunocytochemical detection and colocalization with serotonin and calcitonin gene-related peptide

In this study, the occurrence of 7B2, a highly conserved pituitary protein present in many neuroendocrine tissues and tumors, was investigated for the first time in the neuroendocrine cells (NEC) and neuroepithelial bodies (NEB) of hamster, rat and cat lung, as well as its colocalization with serotonin (5-HT) and calcitonin gene-related peptide (CGRP). Bouin fixed and wax embedded lung tissue was serially cut and immunoreactive sites for 7B2, 5-HT and CGRP were demonstrated on adjacent sections with polyclonal rabbit antibodies, using the streptavidin-biotin peroxidase method. 7B2 immunostained NEB were numerous in the intrapulmonary airways and the alveolar parenchyma, always representing a subpopulation of CGRP labelled NEB, but outnumbering those containing 5-HT. NEC, on the other hand, were only immunoreactive for CGRP and 5-HT. Our results suggest that mammalian NEB are storehouses of heterogenous bioactive substances, which may be important components in the development of bronchopulmonary tumors. Moreover, the ubiquitous presence of 7B2 in NEB supports the idea of a pre- and/or post-exocytotic role in the cellular secretory processes while the lack of 7B2 immunoreactivity in NEC might indicate a distinct function for each of both neuroendocrine cell types.

A rhesus monkey model to characterize the role of gastrin-releasing peptide (GRP) in lung development. Evidence for stimulation of airway growth

Gastrin-releasing peptide (GRP) is developmentally expressed in human fetal lung and is a growth factor for normal and neoplastic lung but its role in normal lung development has yet to be clearly defined. In this study we have characterized the expression of GRP and its receptor in fetal rhesus monkey lung and determined the effects of bombesin on fetal lung development in vitro. By RNA blot analysis, GRP mRNA was first detectable in fetal monkey lung at 63 days gestation, reached highest levels at 80 days gestation, and then declined to near adult levels by 120 days gestation; a pattern closely paralleling GRP expression in human fetal lung. As in human lung, in situ hybridization localized GRP mRNA to neuroendocrine cells though during the canalicular phase of development (between 63-80 days gestation) GRP mRNA was present not only in classic pulmonary neuroendocrine cells, but also in cells of budding airways. Immunohistochemistry showed that bombesin-like immunoreactivity was present in neuroendocrine cells, but not in budding airways, suggesting that in budding airways either the GRP mRNA is not translated, is rapidly secreted, or a related, but different RNA is present. RNase protection analysis using a probe to the monkey GRP receptor demonstrated that the time course of receptor RNA expression closely paralleled the time course of GRP RNA expression. In situ hybridization showed that GRP receptors were primarily expressed in epithelial cells of the developing airways. Thus GRP would appear to be secreted from neuroendocrine cells to act on target cells in developing airways. This hypothesis was confirmed by organ culture of fetal monkey lung in the presence of bombesin and bombesin antagonists. Bombesin treatment at 1 and 10 nM significantly increased DNA synthesis in airway epithelial cells and significantly increased the number and size of airways in cultured fetal lung. In fact, culturing 60 d fetal lung for 5 d with 10 nM bombesin increased airway size and number nearly to that observed in cultured 80 d fetal lung. The effects of bombesin could be blocked by specific GRP receptor antagonists. Thus this study demonstrates that GRP receptors are expressed on airway epithelial cells in developing fetal lung and that the interaction of GRP with the GRP receptor stimulates airway development.

Calcitonin, CGRP and helodermin in endocrine cells of the developing rat lung

Calcitonin gene-related peptide (CGRP), calcitonin and immunoreactive helodermin occur in endocrine cells in the murine airways. In the lungs these cells form clusters, while they occur scattered in the larynx and trachea. In the present study of the developing rat CGRP-immunoreactive cells were more numerous at all stages than the calcitonin- and helodermin-containing ones. A subpopulation of the CGRP-containing cells contained either calcitonin or helodermin. Immunocytochemistry revealed a higher density of CGRP-containing endocrine cells in the lungs of fetal and newborn rats than in the lungs of older rats, while the density of calcitonin-containing cells was largely unchanged. The helodermin-containing cells were few at all developmental stages examined. The concentration and content of CGRP were highest in newborn rats; the levels decreased postnatally. The calcitonin concentration did not change during development while the content increased with age. The concentration and content of helodermin increased with age.

The pulmonary neuroepithelial endocrine system in the quail, Coturnix coturnix. Light- and electron-microscopical immunocytochemistry and morphology

Despite extensive knowledge of the neuroepithelial endocrine (NEE) system in the lungs of species of various vertebrate classes, data on avians are limited. The present investigation deals with the light- and electron-microscopical immunocytochemistry and morphology of pulmonary NEE cells in the quail, Coturnix coturnix. Light-microscopically, serotonin immunoreactivity was detected in numerous solitary and clustered NEE cells located in the cilio-mucous epithelium of primary and secondary bronchi in adult as well as in newly hatched quails. Only in newly hatched quails could a small number of bombesin- and somatostatin-like immunoreactive NEE cells be demonstrated. Electron-microscopical morphology revealed that NEE cells contained dense-cored vesicles of a wide range of diameters and electron densities. Nearly all of the NEE cells were seen to rest on the basement membrane of the cilio-mucous epithelium, lacking direct contact with the luminal surface. Nerve varicosities or nerve endings, of both afferent and efferent morphological appearance, were found directly apposed to the basal portion of NEE cells, invaginating between NEE cells or between NEE cells and adjacent epithelial cells. Often, synaptic specializations could be recognized between NEE cells and nerve terminals. Electron-microscopical immunocytochemistry confirmed that the intraepithelial serotonin-containing cells correspond to the cells with NEE characteristics. Moreover, two types of NEE cells could be distinguished in newly hatched quail lungs. Both types showed serotonin immunoreactivity selectively distributed over the dense-cored vesicles, but somatostatin- and bombesin-like immunoreactivities were only noted in one of the NEE cell types and were never seen colocalized. Thus, the avian NEE system too, harbors at least three different bioactive substances and has a morphology comparable to that of mammals, reptiles and amphibians.

Ontogeny of endocrine cells in the respiratory system of Syrian golden hamsters. I. Larynx and trachea

The ontogeny of protein gene product 9.5 (PGP 9.5), serotonin (5-HT), calcitonin gene-related peptide (CGRP), and calcitonin (CT) immunoreactivity was evaluated in small-granule endocrine cells of hamster laryngotracheal epithelium from fetal day 11 to adulthood. Two centrifugal (proximal-to-distal) patterns of differentiation occur. The first pattern begins during fetal life. Endocrine cells, single and clustered in groups (presumptive- or protoneuroepithelial bodies, pNEBs), initially colocalize immunostaining for PGP 9.5, 5-HT, and CGRP in the larynx and proximal 2/3 of the trachea on day 12 and spread to the caudal trachea on day 13. 5-HT disappears fleetingly during the 24 h preceding birth; otherwise immunoreactivity for all three substances persists into adulthood. The clusters of endocrine cells survive beyond birth but are so diluted by expansion of the nonendocrine epithelium as to become inconspicuous. Since innervation was not actually observed, these clusters may persist as pNEBs, without developing connections to afferent or efferent nerve fibers. The second pattern concerns single small-granule cells stainable for CGRP but not for 5-HT. These cells first appear in the larynx and cartilaginous part of the cranial trachea on postnatal day 3, and in the middle and caudal trachea, on day 5. The cells increase in number on day 7. In adults, they predominate among endocrine cells of the cartilaginous region. A subset of these cells begins to co-express CT proximally on postnatal day 10, reaching the caudal end of the trachea by 3 weeks. A few elements of the older 5-HT-positive population may also become immunoreactive for CT in juvenile hamsters.

Proliferation of guinea pig tracheal epithelial cells induced by calcitonin gene-related peptide

Calcitonin gene-related peptide (CGRP) is contained within and secreted by nerves and neuroepithelial bodies in the airway epithelium. To determine whether CGRP is mitogenic for airway epithelial cells, tracheal epithelial cells isolated from 26 guinea pigs were grown in primary culture for 2 days. Subconfluent cells were exposed to 10(-13) to 10(-9) M CGRP for 4 h and then returned to CGRP-free medium. Proliferation was quantified by direct cell count and by measurement of fractional labeling with the thymidine analog, bromodeoxyuridine (BrdU). CGRP exposure increased both cell number (53,980 +/- 9,870 cells after 10(-9) M CGRP versus 33,910 +/- 5,150 cells after control, P < 0.05) and fractional BrdU labeling (12.9 +/- 2.2% after 10(-11) M CGRP versus 3.9 +/- 0.9%, control; P < 0.01, n = 9) at 24 h after exposure. The mitogenic effect of CGRP persisted at least 3 days after exposure. CGRP-induced proliferation was attenuated by co-incubation with the CGRP receptor antagonist, hCGRP-(8-37). These data demonstrate that CGRP causes proliferation of guinea pig tracheal epithelial cells in primary culture through stimulation of a specific receptor, and suggest a role for this neuropeptide in regulating airway epithelial cell growth.

Immunocytochemical expression of protein gene product (PGP) 9.5 in the cat bronchopulmonary neuroendocrine cells and nerves

Variously fixed, wax-embedded lung and gastrointestinal serial tissue sections from newborn to adult cats were stained with hematoxylin-eosin (H&E), Grimelius' silver, and immunohistochemical techniques using antisera to protein gene product (PGP) 9.5, a neuron-specific protein under strong evolutionary constraints. PGP 9.5 is revealed as a pan-neuroendocrine marker useful for tracing the pulmonary diffuse neuroendocrine system (PDNES) and studying the relationships between neuronal and neuroendocrine elements at various stages of life. Its occurrence is also compared in the pulmonary and the gastrointestinal tract. In spite of a close resemblance to already described neuroepithelial bodies (NEB) of other mammals, cat NEB feature typical constitutional and distributional difference, illustrating interspecies differences. The number of PGP 9.5 immunopositive pulmonary neuroendocrine cells declines gradually after 3 weeks and throughout adult life. Immunoreactivity in neuronal elements is lost after 1 week of age. In gastrointestinal tissues, only neuronal elements immunostain, suggesting functional variations or a separate embryological origin for enteroendocrine cells.

Localization of cholecystokinin-like peptide in neuroendocrine cells of mammalian lungs: a light and electron microscopic immunohistochemical study

We report immunohistochemical localization of cholecystokinin (CCK)-like immunoreactivity at the light and electron microscopy (EM) level in pulmonary neuroendocrine (NE) cells of human and other mammals (monkey, rabbit, rat, hamster, pig, dog and lamb). In addition, immunolocalization of CCK-like peptide was compared with that of bombesin (predominant peptide in human lung) and serotonin (an amine found in NE cells of most species). While CCK-like and serotonin-like immunoreactivity were identified in both solitary NE cells and NE cell clusters (neuroepithelial bodies, NEB) of all species studied, bombesin-like immunoreactive NE cells were found in human and monkey lungs only. The distribution and intensity of immunostaining for CCK-like peptide varied between species with some showing relatively high levels of expression (e.g., monkey, piglet, dog and lamb), others intermediate (human, rabbit) or weak immunostaining (rat, hamster). At the EM level, CCK-like immunoreactivity was localized in dense-core vesicles (DCV), the expected site of peptide storage. Using a double immunolabeling technique, CCK and serotonin were colocalized in some, but not all DCV. The potential role of CCK in the lung (or for other pulmonary peptides) may include a variety of functions such as modulation of bronchial or vascular tone, growth factor-like and/or hormonal effects.

Paracrine effects of bombesin/gastrin-releasing peptide and other growth factors on pulmonary neuroendocrine cells in vitro

Pulmonary neuroendocrine cells (PNEC) are numerous in the fetus where they have been implicated to have a role in fetal lung development. We assessed the effects of putative growth factors, gastrin releasing peptide (GRP), cholecystokinin (CCK), gastrin (GN), serotonin (5-HT), and epidermal growth factor (EGF), some of which are produced by PNEC, either alone or in combination, on cultured fetal rabbit PNEC from 20, 24, and 28 day fetuses. GRP increased the total protein of the cultures over a 7 day period in an age-dependent manner, with greatest effect in cultures from the 24 day fetus, no effect with the 28 day fetus, and an inhibitory effect on 20 day cultures. This was accompanied by an increase in PNEC, which could be blocked by treatment of the cultures with a monoclonal antibody to GRP (2A11). There was no increase in 3H-thymidine labeling of PNEC in GRP treated cultures but an increase in numbers of cells partially stained for 5-HT, suggesting the induction of a precursor cell. Other growth factors had neither an inhibitory nor a stimulatory effect either alone or in combination with GRP. Preliminary studies with 125I-GRP receptor localization suggests that the GRP receptor is mostly expressed on pulmonary fibroblasts, and less on epithelial cells, so that the role for GRP in fetal lung development, at least in the rabbit, is probably indirect, acting via a paracrine mechanism.

Effects of bombesin and gastrin-releasing peptide on human bronchial epithelial cells from a series of donors: individual variation and modulation by bombesin analogs

Human pulmonary neuroendocrine cells produce a variety of hormones, including mammalian bombesin (BN) or gastrin-releasing peptide (GRP). Neuroendocrine cell hyperplasia and increased release of BN-like peptides occur in several diseases of the airways, including chronic obstructive pulmonary disease (COPD) and bronchopulmonary dysplasia. Growth stimulation of human bronchial epithelial cells by BN, as measured in a colony-forming assay, has been reported previously (Willey et al.:Exp. Cell Res. 153:245-248, 1984). In a follow-up to this report, we examined the response of human bronchial epithelial (HBE) cells to BN or GRP in a similar system, using cells derived from 13 human tissue donors. A stimulatory response (increased colony-forming efficiency) was found in cultures from 8 donors, including 3 with COPD. Statistical significance was found for the data from 5 of these 8 donors. The other 5 donors, 1 normal and 4 lung cancer patients, showed inhibition of colony formation by BN or GRP. Statistical significance was found for 3 of these donors. The ability of BN analogs to modulate BN stimulation was examined in cells from a donor with COPD. [psi Leu13,Leu14] BN(1-14), a BN antagonist, blocked the stimulation induced by BN. [D-Cpa6,psi Leu13,Phe14] BN(6-14), a mixed agonist-antagonist, showed partial agonist activity in HBE cells. [D-Phe1,Leu8,9] Litorin, an agonist, also showed agonist activity in a colony-forming assay with cells from these donors. These results indicate that responsiveness to BN/GRP may vary widely in the human population. Responsiveness may be heightened in disease states involving a proliferation of neuroendocrine cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Colocalization of peptide hormones in neuroendocrine cells of human fetal and newborn lungs: an electron microscopic study

This study investigated the colocalization of the peptide hormones bombesin or calcitonin with calcitonin gene related peptide (CGRP) in neuroendocrine cells (NE) in the lungs of human fetuses of varying gestational ages and in the lungs of newborn infants who died with acute or chronic lung disease in the first weeks or months after birth. Double immunolabeling of dense core granules for these peptides was also studied in this same patient population. On-grid double gold immunolabeling was carried out on 29 subjects using anti-bombesin and anti-CGRP and on 22 subjects using anti-calcitonin and anti-CGRP as primary antibodies, the secondary antibodies being labeled with different-size gold spheres. Colocalization of both bombesin and calcitonin with CGRP was demonstrated, not only in the same NE cell, but also on the same dense core granule. Colocalization was rarely found in normal fetuses, and most frequently found in newborn infants with acute lung disease, usually hyaline membrane disease (HMD), or with the development of chronic lung disease in the first weeks or months after birth. Double labeling of the same dense core granules might imply action of peptides in concert, or perhaps one peptide acting in a paracrine role (e.g., on bronchial or bronchiolar smooth muscle) and the second peptide acting in an autocrine fashion on the parent cell (e.g., in the regulation of granule production or release).

Anti-bombesin monoclonal antibodies modulate fetal mouse lung growth and maturation in utero and in organ cultures

Fetal pulmonary neuroendocrine cells (PNECs) contain abundant gastrin-releasing peptide (GRP, mammalian bombesin-like peptide [BLP]). Previously, addition of bombesin resulted in increased fetal lung growth and maturation in utero and in organ cultures. A monoclonal antibody (mAb) to bombesin (2A11) blocked baseline automaturation of lung organ cultures in serum-free medium. In the present study, we analyze lung development following daily in utero administration of 2A11 from gestational days 15-18. Fetal lung treated with 2A11 and then harvested on day 18 demonstrated a dose-dependent decrease in surfactant phospholipid synthesis compared to controls treated with MOPC, an unreactive mAb. However, 2A11-treated fetal lung harvested on day 17 showed paradoxical increases in 3H-choline incorporation into saturated phosphatidylcholine, 3H-thymidine incorporation into DNA, and relative numbers of differentiated type II pneumocytes. In serum-containing day 17 lung organ cultures, 2A11 stimulated choline and thymidine incorporation. Since epidermal growth factor (EGF) is the only agent besides bombesin known to stimulate both fetal lung growth and maturation, we added EGF to serum-free cultures and reconstituted the stimulatory effects. A murine EGF receptor mAb (ERA) blocked 2A11-induced lung growth and maturation in serum-containing cultures, and this effect was overcome by adding EGF. In vivo, ERA also blocked stimulatory effects of 2A11 in fetal lung on day 17. These observations suggest that EGF receptor up-regulation may maintain lung growth and maturation if BLP levels are diminished on day 17. Nonetheless, BLPs appear to be involved in lung maturation on day 18, supporting a role for PNECs in normal lung development.

Molecular cloning and characterization of receptors for the mammalian bombesin-like peptides

The bombesin-like peptides comprise a large family of peptides common to both amphibians and mammals that function as growth factors, neurotransmitters, and paracrine hormones. GRP, the mammalian homolog of bombesin and its receptor, as well as NMB, the mammalian homolog of ranatensin, are expressed in human neoplasms and, in particular, in small cell lung carcinomas (SCLC). To better characterize the physiological roles of bombesin-like peptides, our laboratory has cloned the receptors for GRP in murines, rats, and humans. The 3T3 GRP receptor was isolated and characterized using the two-electrode-voltage-clamp analysis and acquorin-emission methods in xenopus oocytes expression system. The rat and human GRP and NMB receptors were cloned by hybridization at low stringency, using the mouse cDNA receptor probe. Sequence analysis of the receptors showed 384 and 390 amino acids for GRP and NMB receptors, respectively. The homology between the two receptors is 60% and between species in the same receptor, 90%. The receptors belong to the 7-membrane spanning domains superfamily. The specific GRP-R antagonist blocked the response to bombesin in oocytes injected with GRP-R, but failed to do so in oocytes injected with NMB-R. The two receptors differ in their distribution of tissue expression. RNA blot and RNase protection analysis showed the same size of mRNA without alteration in the receptors. RT + PCR analysis performed on genomic DNA revealed similarity between normal and cell DNAs, suggesting no major gene deletion or rearrangement. Southern blot analysis indicated the absence of gene amplification. Sequence analysis of the exonic segments of the receptor genes displayed identical amino acids to the respective cDNAs. None of the genes had classic TATAA box. Somatic cell hybrids localized the GRP-R on the X-chromosome and the NMB-R on chromosome 6. The same sequence of normal genes and cDNAs of GRP and NMB receptors, together with the gene characterization, demonstrated that SCLC cell lines do not require a structural change in receptor protein or genomic rearrangement.

Isolation and sequence of a cDNA encoding the precursor of a bombesinlike peptide from brain and early embryos of Xenopus laevis

A cDNA encoding the precursor of a bombesinlike peptide was isolated from brain of Xenopus laevis. The predicted end product resembles neuromedin B, which was originally isolated from mammalian spinal cord. The mRNA for this precursor was also present in gastrointestinal tract and in ovaries. Moreover, it could be detected in early embryos (stage 2 and stage 10) of X. laevis. These findings suggest novel roles for peptides of the bombesin family in oocyte maturation and early amphibian development.

Immunocytochemical study of the diffuse neuroendocrine system cells in equine lungs

This study was undertaken to investigate the presence of neuroendocrine cells (N.E.C.) by immunocytochemical means in equine lungs during three distinct evolutionary periods: fetal, neonatal and adult. The authors identified bombesin, somatostatin and calcitonin secretory cells. In the fetal lungs the N.E.C. were located in the interstitial tissue and exhibited greater immunoreactivity to bombesin than to the other two neuropeptides studied. A large number of calcitonin-producing cells and a smaller number of bombesin-positive cells were seen in the bronchial and bronchiolar epithelium of newborn Equidae. In the adult equine lungs far fewer N.E.C. were observed than in the earlier stages. Somatostatin-producing cells were not seen in neonatal or adult lung tissue.

Differential diagnostic patterns of lung neuroendocrine tumours

A series of 3 tumourlets (TLs), 81 typical carcinoids (TCs), 14 atypical carcinoids (ACs) (well-differentiated neuroendocrine carcinomas, WDNCs) and 24 small cell-intermediate cell carcinomas (SCC-ICCs) of the lung were studied. Histopathological features were correlated with amine and peptide hormone immunoreactivity and with clinical data. All types of tumours expressed general neuroendocrine (NE) markers: Grimelius positivity and chromogranins were detected more frequently in well-differentiated (TLs, TCs) than in less well differentiated tumours [ACs (WDNCs) and SCC-ICCs] whereas neuron specific enolase (NSE) was prominent in the latter tumours. TLs and peripheral TCs were benign, often showing a paraganglioid pattern and frequently expressing gastrin-releasing peptide (GRP), which is present in the peripheral airways of normal lung. Central TCs were associated with lymph node metastases in 8.5% of the cases, frequently had a trabecular architecture, often associated with human milk fat globule 2 (HMFG2)-positive acinar and rosette-like structures, and were mainly immunostained for the alpha-subunit of human chorionic gonadotrophin (alpha-hCG) and serotonin. ACs (WDNCs) were associated with intrathoracic and/or extrathoracic metastases in 57.1% of the cases with a mortality rate of 35.7%. Their histological and cytological features were intermediate between those of TCs and SCC-ICCs. ACs (WDNCs) expressed serotonin and alpha-hCG less frequently than TCs. All SCC-ICCs were surgically treated and displayed a mortality rate of 91.6% with a mean survival of 10.2 months after operation. These tumours were characterized by high expression of HMFG2 and NSE, while the expression of both orthotopic (serotonin, GRP) and ectopic (ACTH) specific NE substances was very low. Since all TCs (either central or peripheral) had a favourable outcome, while about 36% of ACs (WDNCs) were fatal, the latter seem more appropriately designated "well-differentiated NE carcinomas". The differential diagnosis between different NE tumours of the lung is important and is mainly based on morphology. Both panendocrine and specific immunohistochemical markers are helpful in distinguishing the less aggressive, mostly benign varieties from the more malignant varieties.

CGRP-immunoreactive endocrine cell proliferation in normal and hypoxic rat lung studied by immunocytochemical detection of incorporation of 5'-bromodeoxyuridine

We have tested the suggestion that the reported increase, in hypoxic rats, in the number of lung endocrine cells immunoreactive for the regulatory peptide CGRP is caused by an accumulation of peptide within the cells which renders them more detectable, rather than by a real increase in proliferation. The incorporation of continuously infused 5'-bromodeoxyuridine (BrdU) into nuclei of CGRP-containing cells was studied by immunohistochemistry in the airway and respiratory epithelium of rats kept in a hypoxic (10% O2), normobaric conditions for 7 days and in normoxic, normobaric controls. Some CGRP-immunoreactive cells could also be labelled for BrdU. However, the ratio of the number of cells labelled with both CGRP and BrdU to the number of cells labelled with CGRP alone did not differ significantly between hypoxic and normoxic rats (7.1 +/- 0.7 and 6.1 +/- 1.2, respectively; mean +/- SEM; P = 0.49). These data strongly suggest that CGRP-containing endocrine cells or their precursors do proliferate in adult rat lung, but that the proliferation is not increased significantly in hypoxia.

Isolation and culture of neuroendocrine cells from fetal rabbit lung using immunomagnetic techniques

We describe a novel method for the isolation and subsequent culture of pulmonary neuroendocrine cells (PNEC) from normal fetal rabbit lung using immunomagnetic techniques with a monoclonal antibody, MOC-1. This surface antigen has originally been identified on small cell carcinoma of the lung. Our immunohistochemical studies have shown that MOC-1 cross-reacts with PNEC of human and rabbit fetal lungs on frozen sections, and in fixed cultures of rabbit fetal lung. Using a combination of mechanical and enzymatic disaggregation, a single-cell suspension of fetal rabbit lung was obtained. These cells were incubated with MOC-1 conjugated to magnetic beads. PNEC were selectively removed from the heterogeneous mixture using a magnet, giving up to 2-fold enrichment compared with our previously reported method. These cells were maintained in culture in a functional state for up to 7 days. The ability to prepare PNEC from rabbit fetal lung offers an opportunity to develop in vitro models to investigate the physiologic and biochemical properties of these cells, and ultimately it may lead to a better understanding of their function in health and disease.

Immunocytochemical studies of subtypes of pulmonary endocrine cells in diethylnitrosamine-treated rabbits

New Zealand White rabbits were injected subcutaneously with 20 mg/kg body weight of diethylnitrosamine (DEN), twice per week, starting when they were 1 week old. The animals were sacrificed 6 to 12 months after the first injection and lung tissues were processed for light microscopy. Using serotonin (5HT) and neuron specific enolase (NSE) as markers for the endocrine cells, tissue sections were stained immunocytochemically by the avidin-biotin complex method. Numerous neuroepithelial bodies (NEBs) positive for 5HT, but negative for NSE, were seen in the alveolar duct regions of DEN-treated rabbits. On the other hand, an increased number of solitary endocrine cells immunoreactive for NSE was found in bronchial or bronchiolar epithelia. The results indicate that DEN induced increases in two distinct types of endocrine cells: the component cells of NEBs are positive for 5HT and solitary cells are positive for NSE.

Calcitonin and calcitonin gene-related peptide immunoreactivity and colocalization in newborn cat lung

Calcitonin (CT) and calcitonin gene-related peptide (CGRP) are generated by alternate RNA processing from alpha and beta CT/CGRP genes. In this report, an immunocytochemical investigation was undertaken on the occurrence and distribution of immunoreactive CT as well as its colocalization with CGRP in newborn cat bronchopulmonary endocrine cells. A widespread distribution of solitary endocrine cells and neuroepithelial bodies immunostained for CT was recorded within the lung. In all animals studied, CT immunoreactivity represents a subpopulation of CGRP positive cells, while the intrapulmonary nerve fibers contain only CGRP. To the best of our knowledge, this is the first time that CT and its colocalization with CGRP have been demonstrated immunocytochemically in the cat lung. Our results indicate, that different molecular processing of both CT/CGRP genes may be represented by different patterns in the cellular immunoreactivity of the synthetized peptides.

Gastrin releasing peptide GRP(14-27) in human breast cancer cells and in small cell lung cancer

Immunoreactivity related to the gastrin-releasing peptide (GRP) precursor was detected in four different human breast cancer cell lines. The amounts and the characteristics in extracts from different breast carcinoma cells were compared with cell extracts from small cell lung cancer (SCLC) cells. Two different radioimmunoassays were employed, directed against the amino acid sequence 14-27 of GRP (IR-GRP) or the 42-53 amino acid sequence at the C-terminal end of the GRP precursor (GRP precursor fragment). In extracts from T47D cells cultured under serum free conditions, IR-GRP coeluted with GRP(14-27) or GRP(18-27) in Sephadex G-50 chromatography. No immunoreactivity was detected in the fractions containing high molecular weight components. In a total of 41 human breast carcinoma biopsies from different postmenopausal patients, IR-GRP was detected by immunohistological staining in 39% of the samples. When the GRP(14-27) peptide was added exogenously to breast cancer and SCLC cell lines under serum-free culture conditions, (3H)-thymidine incorporation was stimulated by GRP(14-27) in the SCLC cell lines. Of the breast cancer cell lines only the T47D cell line responded with an increase in (3H)-thymidine incorporation comparable to the increase observed with SCLC cells. Recently, it has been reported that GRP-like receptors are present in some human breast cancer cell lines, including the T47D cell line studied here. The breast cancer cell line T47D therefore expresses the GRP peptide and the receptor for GRP. The identification of GRP-like receptors on T47D cells is in accordance with our present observation of a growth response to GRP(14-27) as evaluated by increased (3H)-thymidine incorporation.

The secretory granule peptides 7B2 and CCB are sensitive biochemical markers of neuro-endocrine bronchial tumours in man

OBJECTIVE

Bronchial tumours are the most frequent cause of the ectopic ACTH syndrome. Two types of tumours are classically responsible: the relatively benign carcinoids and the highly aggressive small cell carcinomas. Both have neuro-endocrine features and are thought to originate from the endocrine component of the bronchial tree. Our objective was to assess the sensitivity of 7B2 and secretogranin 1 as new biochemical markers of neuro-endocrine differentiation in these tumours in comparison with gastrin releasing peptide.

METHODS

Tissue concentration of 7B2, secretogranin 1 fragments (GAWK and CCB), gastrin releasing peptide and beta-endorphin were measured in normal human lung (n = 4), bronchial carcinoid tumours with (n = 5) and without (n = 15) the ectopic ACTH syndrome, small cell carcinomas (n = 2), squamous cell carcinomas (n = 11) and adenocarcinomas (n = 6). Molecular weight forms of immunoreactive--ACTH, -GAWK, -gastrin releasing peptide, and -7B2 were also examined using gel exclusion chromatography and Western blot analysis.

RESULTS

We detected 7B2 immunoreactivity in 19 of 22 neuro-endocrine lung tumours (with values ranging from less than 5 to 555 fmol/mg wet weight tissue), CCB immunoreactivity in 20 of 22 tumours with neuro-endocrine features (with values ranging from less than 5 to 19,875 fmol mg wet weight tissue) and gastrin releasing peptide immunoreactivity in 10 of 22 neuro-endocrine lung tumors (with values ranging from less than 5 to 11,132 fmol/mg wet weight tissue). Immunoreactive 7B2 and CCB were detected neither in tumours with non-endocrine features, nor in the four normal lung specimens. Differing molecular weight forms of immunoreactive 7B2 in two bronchial carcinoids associated with the ectopic ACTH syndrome showed a predominant signal corresponding to a molecular weight of 22 kDa; in addition, a second signal of 19 kDa was also present. The differing molecular weight forms of immunoreactive ACTH related peptides in the five tumours responsible for the ectopic ACTH syndrome showed, in addition to ACTH1-39, the constant presence in variable proportions of corticotrophin-like intermediary lobe peptide (or ACTH18-39). The differing molecular weight forms of immunoreactive GAWK showed heterogeneous results with materials eluting at Kav of 0, 0.3 and 0.4 respectively. In the three bronchial carcinoids studied, two immunoreactive gastrin releasing peptide molecular weight forms were always found at Kav of 0.5 and 0.85 corresponding to gastrin releasing peptide and its fragment 14-27 respectively.

CONCLUSION

Our results show that 7B2 and the two fragments of secretogranin 1 (GAWK and CCB) are the best biochemical markers of neuro-endocrine differentiation in human lung tumours.

Chemical coding of endocrine cells of the airways: presence of helodermin-like peptides

The epithelium of the airways is rich in endocrine cells containing serotonin and/or a wide variety of regulatory peptides. These cells usually occur in clusters in the lungs but are also found scattered in the larynx and trachea. In the present study, endocrine cells in the airways of mouse, rat, hamster, guinea pig, pig, sheep and squirrel monkey were examined for the presence of serotonin, helodermin-like peptides and other regulatory peptides using immunocytochemistry and radioimmunoassay. In addition, we looked for the protein gene product 9.5 (PGP), which occurs in many peptide hormone-producing endocrine cells in the body. Both clustered and scattered endocrine cells in the airways were found to display coexistence of serotonin and peptides, such as a helodermin-like peptide, calcitonin and calcitonin gene-related peptide (CGRP). The PGP-immunoreactive cells were numerous and included elements containing serotonin and/or regulatory peptides. An additional PGP-immunoreactive endocrine cell population lacked serotonin and regulatory peptides. Helodermin-immunoreactive material was demonstrated in endocrine cells of the airways in the mouse and hamster but not in any of the other species studied. Serotonin was an endocrine cell constituent in all the species studied. Calcitonin and CGRP could be demonstrated by immunocytochemistry in the mouse, rat, and hamster, but not in the guinea pig, sheep, pig and monkey.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical study on gastrin-releasing peptide-containing peripheral nerve fibers in rat, macaque and human

Distribution of gastrin-releasing peptide (GRP)-containing peripheral nerve fibers in the respiratory organs, digestive tracts and hearts of rat, monkey and human was studied with immunohistochemical method. In the trachea, GRP-immunoreactive nerve fibers were observed in the lamina propria and surrounded ducts and acini of tracheal serous glands with a basket-like appearance. In the lung, immunoreactive nerve fibers were scattered in the lamina propria of bronchi and bronchioles, and also the adventitia of veins. In the digestive organs, such as esophagus, duodenum and jejunum, numerous GRP-immunoreactive nerve fibers were distributed in the lamina propria and muscle layer; especially in the former layer where they were seen running up to the apical part of villi. GRP-containing nerve bundles and branched fibers were also observed in the atrial muscle layer. These results gave a morphological basis to future studies of the functional significance of GRP on autonomic mechanisms.

Raised levels of latent collagenase activating angiogenesis factor (ESAF) are present in actively growing human intracranial tumours

Endothelial cell stimulating angiogenesis factor (ESAF) is a potent, low molecular mass mitogen, specific for endothelial cells. In common with various protein growth factors, it displays angiogenic activity in a variety of biological test systems. However, it differs from these other factors by virtue of its low molecular mass and its ability to activate latent matrix metalloproteinases in a dose dependent manner. This activity has been used to quantify the factor in both normal and diseased brain tissue. The concentration of ESAF determined in biopsies from different types of intracranial tumours varied: in some tumour types the level was close to that of control samples whereas in others it rose to levels comparable to those encountered in the pineal gland, the richest source of ESAF in mature mammals. Tumours considered to be benign contained significantly less ESAF than those neoplasms classified as being malignant (P = 0.025). There was also a correlation between the mitotic activity of tumour samples, as determined by conventional H & E histochemical staining and the ESAF concentration present. These findings agree with previous studies in which elevated ESAF levels have been found in tissue where proliferation of vascular elements has been observed.