Detection of human probombesin mRNA in neuroendocrine (small cell) carcinoma of the lung. In situ hybridization with cRNA probe

Breast cancer cell-associated endopeptidase EC 24.11 modulates proliferative response to bombesin

We have investigated the production, growth and inactivation of gastrin-releasing peptide (GRP)-like peptides in human breast cancer cell lines. Radioimmunoassay detected GRP-like immunoreactivity (GRP-LI) in T47D breast cancer cells but not in the conditioned medium, indicating rapid clearance. No GRP-LI was found in the ZR-75-1 or MDA-MB-436 cells or their conditioned medium. High-performance liquid chromatography (HPLC) analysis of the GRP-LI in the T47D cells revealed a major peak, which co-eluted with GRP(18-27), and a minor more hydrophilic peak. In vitro stimulation of T47D cell growth by bombesin (BN) was enhanced to 138% of control levels (bombesin alone) by the addition of the selective endopeptidase EC 3.4.24.11 inhibitor phosphoramidon (0.1 ng ml(-1)). Fluorogenic analysis using whole cells confirmed low levels of this phosphoramidon-sensitive enzyme on the T47D cells. This enzyme, previously unreported in human breast cancer cells, significantly modulates both T47D growth and its response to BN-induced growth.

In situ hybridization and its diagnostic applications in pathology

In situ hybridization (ISH) is a technique by which specific nucleotide sequences are identified in cells or tissue sections. These may be endogenous, bacterial or viral, DNA or RNA. On the basis of research applications, the technique is now being translated into diagnostic practice, mainly in the areas of gene expression, infection and interphase cytogenetics. Diagnostic applications are most often based on short nucleotide sequences (oligomers) labelled with non-isotopic reporter molecules, and sites of binding may be localized by histochemical or immunohistochemical methods. The technique can be applied to routinely fixed and processed tissues; with some targets, it is even possible to obtain hybridization in autopsy material. ISH has been used to detect messenger RNA (mRNA) as a marker of gene expression, where levels of protein storage are low; for example, to confirm an endocrine tumour as the source of excess hormone production. Its application in infectious diseases has to date been mainly in viral infections, such as the typing of human papillomavirus (HPV) or the detection of Epstein-Barr virus by the presence of small nuclear RNAs (EBERs). The expression of mRNAs for histone proteins has been used to detect cells in S phase, and related methods may be applied to detect apoptotic cells. Using probes to chromosome-specific sequences, it is possible to detect aneuploidy, and to document changes in specific chromosomes, which may have prognostic significance in some tumours, such as B-cell chronic lymphatic leukaemia. Using sequence-specific probes, translocations can be identified, such as the t(11;12) of Ewing's sarcoma. This review presents an outline of the technique of in situ hybridization and discusses areas of current and potential diagnostic application.

Comparative histology of pulmonary neuroendocrine cell system in mammalian lungs

It is increasingly recognized that neuroepithelial endocrine cells and organoid clusters of these cells termed neuroepithelial bodies are widely distributed in the respiratory tract of vertebrates. This review focuses on the neuroepithelial endocrine system in the airway epithelium of mammals according to observations made in a wide range of species, as it appears in light and electron microscopy by means of various visualization techniques under normal and experimental conditions. Because there are similarities but also marked differences between species, wherever possible studies in human airways are emphasized. Conventional histochemical and ultrastructural studies including microspectrofluorimetry have demonstrated the amine-handling properties and the presence of neurosecretory granules in neuroendocrine cells of the epithelium of all mammals studies so far. The neuroepithelial bodies are innervated by morphological afferent- and efferentlike synaptic specializations. These, together with the presence of reciprocal synapses, emphasize that these cells may be involved in dual functions of chemoreception and secretion. Light and electron microscopic immunohistochemistry has demonstrated that neuroepithelial endocrine cells may contain various biogenic agents, suggesting that the neuroendocrine system is highly heterogeneous. Neural elements may interact in a complex manner, and the activation of certain neural pathways may control the release of biogenic substances to influence physiological airway functions. They may be particularly relevant in pulmonary diseases. Consequently, the function of this system is complex and it is highly probable that many of its aspects are still not elucidated.

In situ hybridization techniques for the analysis of gene expression: applications in tumor pathology

In situ hybridization (ISH) has emerged over the past decade as an extraordinarily sensitive technique for the detection of gene expression at the cellular level. Advances in probe preparation and labeling methods have facilitated the transfer of this technology from the research laboratory to the clinical arena. In contrast to immunohistochemistry, which is dependent on the protein content of cells, ISH analyses permit the identification of cells on the basis of their contents of specific messenger RNAs (mRNAs) encoding the products of interest. These methods provide a critical approach for the analysis of heterogeneity in tumors that typically contain cells at different phases of neoplastic progression and at multiple levels of differentiation and functional activity. In situ hybridization methods have been of particular value for studies of mRNAs encoding oncogenes, hormones, secretory proteins, cytokines, and a wide variety of other cellular products. Advances in ISH technology, including polymerase chain reaction (PCR) based methods, offer particular promise for examining genes with low levels of expression at the cellular level.

Immunocytochemical characterization of neuroendocrine tumours of the larynx

Twenty-two neuroendocrine tumours of the larynx were investigated using a panel of immunocytochemical markers. Three were small cell carcinomas, eight were large cell neuroendocrine carcinomas and 11 were paragangliomas. Twenty were positive for protein gene product 9.5, 19 for neuron-specific enolase, 15 for chromogranin A, nine for bombesin, eight for substance P, eight for neuropeptide Y, eight for metenkephalin, seven for somatostatin, five for calcitonin, eight for calcitonin gene-related peptide and one for vasoactive intestinal polypeptide. Bombesin immunoreactivity was largely restricted to the small cell carcinomas and large cell neuroendocrine carcinomas and neuropeptide Y, metenkephalin and substance P to the paragangliomas. This comprehensive immunocytochemical analysis of neuroendocrine tumours of the larynx demonstrates that these tumours represent special entities but have similar patterns of immunostaining to those of neuroendocrine tumours in other sites.

Introduction to molecular endocrine pathology

The applications of molecular techniques to endocrine pathology have been rapidly expanding in the past few years. This article reviews some of the basic concepts and techniques in molecular biology and summarizes recent applications of these techniques in the study of endocrine diseases. The applications of clonal analysis, hybridization techniques, single strand conformation polymorphism analysis, and the polymerase chain reaction technique in the study of neoplasms including specific mutations of oncogenes and suppressor genes in various endocrine tissues are discussed. The rapidly developing field of homeobox genes and their role in development including studies of normal pituitary development and pituitary tumor expression of the Pit-1 transcription factor, a member of the POU family of homeobox genes, are also summarized.Endocr Pathol 4:64-72, 1993.

Detection of calcitonin and calcitonin gene-related peptide mRNA in human medullary thyroid carcinoma. A retrospective study

In situ hybridization finds many applications in modern pathology. In many cases, special attention is paid to the processing of the tissues prior to in situ hybridization. In order to investigate the value of RNA in situ hybridization (RISH) in retrospective studies, we performed RISH for calcitonin and calcitonin gene-related peptide (CGRP)-I and -II mRNA in eight medullary thyroid carcinomas processed in 1981-1983. RISH was successful with radioactive calcitonin and CGRP-I probes. With biotinylated probes, only calcitonin-specific probes gave adequate results. The concentrations of CGRP mRNA were probably too low to be detected by non-radioactive RISH. The results of RISH were correlated with the immunohistochemical localization of the polypeptides. The results matched in all cases except one, where hybridization for calcitonin mRNA was found, but no immunoreactive calcitonin polypeptide. We conclude that RISH can be successfully used for retrospective analysis, even after long storage of tissue embedded in paraffin.

Estradiol regulates class I alcohol dehydrogenase gene expression in renal medulla of male rats by a post-transcriptional mechanism

Rat kidney contains alcohol dehydrogenase (ADH) activity which appears to be identical to the class I ADH expressed in liver. Treatment of male rats with estradiol for 10 days induced ADH activity and protein in the kidney approximately 3-fold. This was not the result of suppression of testosterone levels by estrogen, as castration did not increase ADH activity. In situ hybridization of kidney sections showed that ADH transcripts were localized to the medulla, that the basal level of mRNA is very low in the male, and that the induction of ADH mRNA by estradiol was approximately 10-fold. As estimated from Northern blot analysis, the induction of the mRNA was approximately 7-fold. Thus, induction of ADH mRNA substantially exceeded the increase of ADH activity and protein. Since the estradiol-treated rats lost weight relative to the oil-injected controls, the effect of starvation on ADH mRNA in kidney was examined. Starvation decreased kidney ADH activity by about 30% but increased mRNA about 2-fold. Time course experiments demonstrated induction of ADH mRNA by estradiol within 1 h with the maximum level achieved by 24 h. The transcription rate of the ADH gene as assessed by nuclear run-on assays performed at 1 and 24 h after treatment with estradiol was unchanged. We conclude that estradiol induces ADH mRNA in kidney by a post-transcriptional mechanism.

In situ hybridization: a valuable tool in diagnostic pathology

In situ hybridization or hybridohistochemistry has evolved in recent years in a new histologic modality. In situ hybridization (ISH) can be used for the detection of DNA (DISH) or RNA (RISH). The potential diagnostic value within a pathologic setting are well recognized. In this review paper, we summarize the use of DISH in a pathologic setting for the detection of chromosomal aberrations and localization of DNA-viruses like cytomegalovirus and Epstein Barr virus. RISH which is still in a more experimental stage can be applied for the localization of RNA-virus, like human immunodeficiency virus. However, the most important application of RISH will be the detection of gene-expression at the level of mRNA. Potentially this has many applications especially in early diagnostics of neoplastic tissues. Finally, we have summarized some pitfalls which may hamper the introduction of in situ hybridization for diagnostic purposes and some future developments in ISH.

Neuroendocrine differentiation in lung tumours

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Estradiol induces class I alcohol dehydrogenase activity and mRNA in kidney of female rats

Rat kidney contains alcohol dehydrogenase (ADH) activity which appears to be similar or identical to the class I ADH expressed in liver. Both tissues contain a 1.6-kb transcript which hybridizes with an ADH cDNA under stringent conditions. Kidney ADH activity is responsive to estradiol. The enzyme activity in the kidneys of sham-operated and ovariectomized animals was the same. Treatment of either group of animals by intramuscular injection of estradiol (1 mg/kg body wt/day) for 10 days induced ADH activity in kidney two- to threefold, whether the activity was expressed as U/g tissue, U/g protein, or U/mg DNA. Estradiol induced kidney ADH mRNA in both ovariectomized and sham-operated rats approximately twofold. Thus, induction of ADH mRNA accounts for the increase in ADH activity. In situ hybridization indicated that the ADH mRNA was present in the inner cortex and medulla of the kidney. Methylation patterns of the ADH gene were examined. The gene resides in a methylated region of chromatin without any of the typical features of a HpaII tiny fragment (HTF) island. Two MspI sites flanking the transcription start site are undermethylated in liver compared with kidney and spleen. This suggests that methylation of this gene may play a role in the tissue-specific expression of ADH.

Expression of mRNA for interleukin-5 in mucosal bronchial biopsies from asthma

We have attempted to identify mRNA for IL-5 in endobronchial mucosal biopsies from asthmatics and controls, using the technique of in situ hybridization. Bronchial biopsies were obtained from 10 asthmatics and 9 nonatopic normal controls. A radio-labeled cRNA probe was prepared from an IL-5 cDNA and hybridized to permeabilized sections. These were washed extensively before processing for autoradiography. An IL-5-producing T cell clone derived from a patient with the hyper-IgE syndrome was used as a positive control. As a negative control, sections were also treated with a "sense" IL-5 probe. Specific hybridization signals for IL-5 mRNA were demonstrated within the bronchial mucosa in 6 out of the 10 asthmatic subjects. Cells exhibiting hybridization signals were located beneath the epithelial basement membrane. In contrast, there was no hybridization in the control group. No hybridization was observed with the sense probe. The six IL-5 mRNA-positive asthmatics tended to have more severe disease than the negative asthmatics, as assessed by symptoms and lung function, and showed a significant increase in the degree of infiltration of the bronchial mucosa by secreting (EG2+) eosinophils and activated (CD25+) T lymphocytes. Within the subjects who showed positive IL-5 mRNA, there was a correlation between IL-5 mRNA expression and the number of CD25+ and EG2+ cells and total eosinophil count. This study provides evidence for the cellular localization of IL-5 mRNA in the bronchial mucosa of asthmatics and supports the concept that this cytokine regulates eosinophil function in bronchial asthma.

Expression of chromogranin A mRNA in small cell carcinoma of the lung

Chromogranin A (CgA) is the most specific neuroendocrine marker but in small cell carcinoma of the lung (SCCL) CgA immunoreactivity cannot always be detected, possibly owing to poor granularity. The localization of CgA mRNA could be a more useful indicator of CgA synthesis in SCCL. We have therefore studied the expression of CgA mRNA in SCCL, using in situ hybridization and Northern blot analysis, comparing it with CgA immunoreactivity. The expression of CgA mRNA and immunoreactivity in other types of lung tumours was also investigated. Freshly fixed, surgically resected SCCL (n = 5), adenocarcinoma (n = 10), squamous cell carcinoma (n = 10), large cell carcinoma (n = 5), and primary lymphoma (n = 2) were examined. Weak immunoreactivity to CgA was seen in one SCCL but all five strongly expressed CgA mRNA. The specificity of the in situ hybridization signal and the probe was confirmed by the use of a sense probe and Northern blot analysis. Non-SCCLs were negative for both CgA mRNA and immunoreactivity. This study provides evidence for CgA synthesis in SCCL and confirms the specificity of CgA for neuroendocrine differentiation. In situ hybridization appears to be a very useful tool for investigating the nature of tumour cells, especially in the absence of the end product of the gene transcript.

Expression of the gastrin-releasing peptide gene in carcinomas of the breast

Expression of gastrin-releasing peptide (GRP), the mammalian homologue of the amphibian bombesin, has been investigated at gene and protein level in a series of 28 primary breast carcinomas, in 6 mammary cancer cell lines and in one transplantable rat mammary carcinoma. Moderate to strong expression of GRP mRNA was detected in 5 breast carcinomas by Northern blot analysis with a pre-pro-GRP probe; 4 other cases were weakly reactive. Two of these cases also gave a specific immunocytochemical reaction for GRP, controlled with absorption experiments. Correlation with NE differentiation [as shown by chromogranins (Cg) and/or NSE and/or Grimelius positivity] was low, since only one case of breast carcinoma co-expressed GRP and Cg mRNAs. Breast cancer cell lines and a rat carcinoma gave negative results. GRP production in breast cancer did not appear to bear prognostic implications, but longer follow-up periods are needed to confirm these data. As shown in small-cell lung cancer, GRP might be involved in autocrine growth control mechanisms of a group of breast carcinomas.

Growth factors in lung cancer: possible etiologic role and clinical target

Growth factors play an important role in the pathogenesis and progression of all histologic types of lung cancer. Ideas for the exploitation of growth factors in lung cancer management are growing. The inhibition of the interaction between growth factors and their receptors, utilization of negative growth factors, interruption of the signal transduction pathways, or effecting decreased growth factor and/or receptor expression, could result in cell death, and all seem logical possibilities for new and specific treatment approaches. There can be no question that observations of the abnormal expression of growth factors have made a startling impact in every aspect of cancer research. The elucidation of their role in cell proliferation, coupled with our growing knowledge of the functions of oncogenes, has given birth to a unifying concept for the etiology of malignant transformation, which hopefully will translate into new, less toxic, more effective, and desperately needed lung cancer treatment.

Detection of endothelin immunoreactivity and mRNA in pulmonary tumours

Paraffin sections of 66 surgically resected lung tumours were immunostained with antisera to human endothelin-1 and to the C-terminal peptide of big endothelin. With both antisera, strong immunoreactivity was demonstrated in 11 of 15 squamous cell carcinomas and 11 of 16 adenocarcinomas. Focal immunoreactivity was seen in small cell carcinoma (2/12), large cell carcinoma (2/5), and carcinoid tumours (2/11). Four lymphomas and three sarcomas did not show endothelin immunoreactivity. Cryostat sections of 22 of the 66 tumours were hybridized with radiolabelled complementary RNA probes prepared from the 3' non-coding region of endothelin-1 cDNA, and the chromosomal genes encoding endothelin-2 and -3. In situ hybridization demonstrated the presence of endothelin mRNAs in 4 of 7 squamous cell carcinomas and in 5 of 8 adenocarcinomas, in a pattern similar to that shown by immunocytochemistry. No hybridization signals were obtained from the other types of tumours. In lung tissue adjacent to the tumours, endothelin-like immunoreactivity and mRNA were detected in pulmonary endocrine cells and, in some cases, other epithelial cells, and in alveolar capillary endothelial cells. This study demonstrates the expression of endothelin in a number of pulmonary tumours and suggests a possible role for this peptide in the growth and/or differentiation of these tumours.

Expression of gastrin-releasing peptide (human bombesin) gene in large cell undifferentiated carcinoma of the lung

Production of the growth factor gastrin-releasing peptide (GRP) or human bombesin has been shown to be a feature of neuroendocrine tumours of the lung, particularly small cell carcinoma, and is possibly responsible for the characteristically rapid growth of this tumour. Large cell undifferentiated carcinoma of the lung (LCC) is also characterized by rapid growth and there is increasing evidence that some LCCs exhibit neuroendocrine differentiation. We therefore investigated GRP/bombesin immunoreactivity and the expression of GRP gene in ten LCCs. Histologically, all were composed of large cells with abundant cytoplasm, open nuclei, and prominent nucleoli, and there was no evidence of squamous, glandular, or neuroendocrine differentiation. At the ultrastructural level, most showed squamous or glandular differentiation but none contained neuroendocrine granules. None of the tumours showed immunoreactivity for GRP/bombesin but seven of the ten showed a focal hybridization signal when treated with 32P-labelled GRP cRNA probes, indicating the presence of GRP mRNA. This was confirmed by northern blot analysis. This study shows for the first time that GRP gene is expressed in LCC. The production of GRP may contribute to the aggressive behaviour of LCC.

Gut endocrine and neural peptides

The once exponential growth in the number of new gut endocrine peptides being discovered has become slightly slower in recent years, and expansion of the field of gut hormones has involved mainly the application of new investigative methods. Some new peptides have been described and major inroads have been made into establishing the ontogeny of gut endocrine cells, the origins and pathways of the enteric innervation, and the involvement of the diffuse neuroendocrine system as a whole in disease states. Further insight is being gained into the functional activity of the peptide cell system by studying the control, sites and rates of peptide gene expression, and the localization and characterization of peptide binding sites on target cells.

Localisation of mRNA and co-expression and molecular forms of GRP gene products in endocrine cells of fetal human lung

The presence of bombesin (gastrin-releasing peptide, GRP)-like immunoreactivity in mucosal endocrine cells of human fetal lung is well established. In this study we have investigated the localisation of pro-GRP mRNA and GRP gene products and compared the distribution and levels of extractable GRP- and C-terminal flanking peptide of human pro-GRP-like immunoreactivity in order to verify synthesis and to investigate their coexistence and molecular forms. Human fetal lungs (14 to 23 weeks gestation) were immunostained, and extracts were assayed using region-specific antisera to pro-GRP. Additional antisera to chromogranin and protein gene product 9.5 (PGP 9.5) were used for immunostaining by the peroxidase anti-peroxidase technique and for double immunofluorescence staining using antisera raised in two species. Immunoreactivity for both bombesin (GRP) and flanking peptide was seen mainly in the same endocrine cells, but more cells were stained with antisera to flanking peptide than with antiserum to bombesin (GRP). In situ hybridisation showed that pro-GRP mRNA was present and thus synthesis of the peptides was taking place. Endocrine cells and nerve fibres were PGP 9.5-immunoreactive, and a subset of cells was immunoreactive for bombesin gene products. Radioimmunoassay and chromatography show that pro-GRP is present in both the uncleaved and cleaved forms, and, in agreement with immunocytochemistry results, that an excess of C-terminal peptide of pro-GRP is detectable. It is therefore concluded that GRP-like peptides and flanking peptide are co-localised in human pulmonary endocrine cells, but the latter is found in larger concentrations than free GRP. Thus GRP-like peptides may be secreted separately from the flanking peptide(s) of pro-GRP.(ABSTRACT TRUNCATED AT 250 WORDS)