Lung tumour cell lines synthesizing peptide hormones established from tumours of four histological types: characterization of the cell lines and analysis of their peptide hormone production

How cancer hijacks the body's homeostasis through the neuroendocrine system

During oncogenesis, cancer not only escapes the body's regulatory mechanisms, but also gains the ability to affect local and systemic homeostasis. Specifically, tumors produce cytokines, immune mediators, classical neurotransmitters, hypothalamic and pituitary hormones, biogenic amines, melatonin, and glucocorticoids, as demonstrated in human and animal models of cancer. The tumor, through the release of these neurohormonal and immune mediators, can control the main neuroendocrine centers such as the hypothalamus, pituitary, adrenals, and thyroid to modulate body homeostasis through central regulatory axes. We hypothesize that the tumor-derived catecholamines, serotonin, melatonin, neuropeptides, and other neurotransmitters can affect body and brain functions. Bidirectional communication between local autonomic and sensory nerves and the tumor, with putative effects on the brain, is also envisioned. Overall, we propose that cancers can take control of the central neuroendocrine and immune systems to reset the body homeostasis in a mode favoring its expansion at the expense of the host.

A new cause of Zollinger-Ellison syndrome: non-small cell lung cancer

Numerous epidemiologic studies suggest a relationship between lung cancer and peptic ulcer disease. Furthermore, various lung cancers synthesize and release a number of peptides such as gastrin and gastrin-releasing peptide that could cause acid hypersecretion; however, Zollinger-Ellison syndrome (ZES), because of a lung tumor, has never been described. We report such a patient for the first time. A 60-year-old man with a non-small cell lung carcinoma (large cell type) presented with diarrhea, heartburn, abdominal pain, and duodenal ulcers. Evaluation showed ZES was present (fasting hypergastrinemia, hyperchlorhydria) and control of all symptoms by omeprazole. No abdominal or cardiac tumor, the other known locations of gastrinomas causing ZES, was found on detailed tumor imaging studies. Resection of the lung tumor resulted in a decrease in gastrin levels to normal values. Plasma radioimmunoassays showed elevated gastrin, chromogranin A and normal levels of gastrin-releasing peptide, and 9 other hormones. The tumor showed similar immunocytochemical results. The characteristics of this case are compared with 100 cases of sporadic abdominal gastrinomas, and the evidence reviewed suggests why ZES should be considered in patients with lung cancer with peptic symptoms.

Spectrum of neuroendocrine differentiation in lung cancer cell lines featured by cytomorphology, markers, and their corresponding tumors

Lung cancer cell lines which show features of neuroendocrine (NE) differentiation can be divided into 4 types which have distinct clinicopathologic correlates: classic small cell lung cancer (SCLC), variant SCLC, pulmonary carcinoid, and non-small cell lung cancer with NE features (NSCLC-NE). These cell lines form a spectrum regarding their degree of NE differentiation which ranges from high levels seen in carcinoid cell lines to very low which is typical of the variant SCLC. A careful comparison of the properties of tumors and their cell lines and correlating these data with the clinical history of the patient has markedly enhanced the relevance of cell lines as models for NE biology and lung carcinogenesis.

Gastrin-releasing peptide in normal and neoplastic human lung: measurement and biochemical characterization

Levels of gastrin-releasing peptide (GRP) were determined by radioimmunoassay in human normal main and lobar bronchus and parenchymal lung tissue extracts. It was found that the level of GRP differed significantly between all 3 areas. The concentration of GRP was statistically higher in main bronchus (median 6.74 ng/g) compared to both lobar bronchus (median 4.79 ng/g) and parenchymal lung (median 1.73 ng/g), and also statistically higher in lobar bronchus compared to parenchymal lung. Chromatographically, GRP-immunoreactivity in both main and lobar bronchial extracts corresponded to GRP1-27 and GRP18-27, while in lung tissue only one major species was identified which corresponded in retention time to GRP18-27. No significant difference was detected when the levels of GRP in normal lobar bronchus and normal lung tissue were compared to the levels in lobar bronchus and lung taken from patients with lung carcinoma, at a site adjacent to the carcinoma. However, a significant difference was observed between the GRP content of normal main bronchus compared to main bronchus from patients with carcinoma. GRP was measured in 26/56 lung carcinomas examined. The levels ranged from 42,000 ng/g in a carcinoid tumour to 0.18 ng/g in a squamous-cell carcinoma, though only in 6 tumours were the levels outside the range determined for normal pulmonary tissue. Chromatography of selected tumour extracts of different histopathologies showed that there were differences in the GRP products present.

Small cell lung cancer cell lines secrete predominantly ACTH precursor peptides not ACTH

A panel of 18 well characterised human small cell lung cancer (SCLC) cell lines was assessed for the production of adrenocorticotrophin (ACTH) and its precursor peptides, pro-opiomelanocortin (POMC) and pro-ACTH. These precursor peptides were measured directly using a novel two-site immunoradiometric assay (IRMA) based on monoclonal antibodies, in conjunction with a similar IRMA for ACTH 1-39. Significant concentrations of ACTH precursors were secreted by 10 of the 18 cell lines (56%). The low levels of ACTH immunoreactivity detected in seven cell lines could be accounted for by the known cross-reactivity of precursors in the ACTH IRMA. This suggests there is little, if any, processing of ACTH precursors to ACTH. Cell pellet extracts contained undetectable or low levels of ACTH precursors and ACTH, indicating that these peptides are not stored intracellularly. During the growth of the SCLC cells in vitro ACTH precursors accumulated progressively in the culture medium. Thus the combination of a direct assay for the ACTH precursors and the panel of SCLC cell lines provides a valuable in vitro model for the expression of POMC in human tumours.

Association of mRNA and eIF-2 alpha with the cytoskeleton in cells lacking vimentin

The human bladder carcinoma cell lines RT4 and T24 and the human breast adenocarcinoma cell line MCF-7 were found to be negative for vimentin when studied by means of immunofluorescence and immunoblotting. Northern blot analysis revealed that these cells lacked detectable levels of vimentin mRNA with the exception of T24, which contains trace amounts of vimentin mRNA compared to the RNA level in vimentin-containing HeLa cells. CAT assays performed on these cells showed that a hamster vimentin promoter is inactive in RT4 and MCF-7 cells. In the vimentin-lacking cells, the binding of polyribosomes, specific mRNAs, and translation factor eIF-2 alpha to the cytoskeletal fraction was examined. Our results indicate that the presence of a vimentin network is not crucial for the association of the translation machinery with the cytoskeleton. Furthermore, in these vimentin-negative cell lines the immunofluorescence staining pattern of eIF-2 alpha shows a fibro-granular structure that has no resemblance to the cytokeratin or actin cytoskeleton present in these cells.

Multiple peptide hormone producing adenocarcinoma of lung with neurotensin and CRF-like immunoreactivity

A pulmonary cancer of a 43 year-old-man was classified according to WHO-criteria as a poorly differentiated adenocarcinoma because of demonstration of mucinous substances in tumor cells and in rarely occurring acinar lumina. Immunohistochemical reactivity for several peptide hormones was detected in the predominant solid parts of the carcinoma. In many tumor cells an immunoreactivity to neurotensin, bombesin and - according to the elevated serum levels - to ACTH, CRF and calcitonin was found. Therefore the present lung cancer must be defined as a combined carcinoma composed of mucous producing and endocrine cell types. Because peptide hormone production is not restricted to the classical "neuro"-endocrine lung tumors, the histogenesis of this heterogeneous lung cancer is discussed.

Radiosensitivity related to neuroendocrine and endodermal differentiation in lung carcinoma lines

A panel of human lung carcinoma lines was studied with respect to hormone production and intermediate filament expression to distinguish between endodermal and neuroendocrine differentiation. An index of the degree of neuroendocrine differentiation of each line was derived from the presence or absence of hormone production, cytokeratins, neurofilaments and an embryonic endodermal cell marker, which allowed identification of three groups showing high, intermediate or low neuroendocrine expression. This grouping correlated well with the in vitro radiosensitivity of the lines, those expressing pure neuroendocrine features being significantly more radiosensitive than those with an endodermal phenotype, with the intermediate group having intermediate sensitivity. Use of such an index might predict those patients likely to benefit from the use of radiotherapy in their management.

Detection of mRNA encoding calcitonin, calcitonin gene related peptide and proopiomelanocortin in human tumors

Expression of the calcitonin (CT)/calcitonin gene related peptide (CGRP) gene and the proopiomelanocortin (POMC) gene has been demonstrated by Northern blot hybridization analysis of RNA extracted from human medullary thyroid carcinoma (MTC), pheochromocytoma and lung carcinoma. CT mRNA in these tumors could not be distinguished in size from CT mRNA isolated from normal human thyroid tissue. CGRP mRNA (previously demonstrated in 12 out of 12 lung tumor cell lines investigated) could not be detected in 13 primary lung tumors or 10 metastases thereof. The length of POMC mRNA in MTCs (present in all 4 metastases investigated but not in 7 primary tumors) and pheochromocytomas is about 100 nucleotides more than pituitary POMC RNA. In lung tumors 2 POMC RNA species can be detected, one of the same size as in pituitary tissue and one about 100 nucleotides larger.

Pulmonary adenocarcinoma of fetal type: alternating differentiation argues in favour of a common endodermal stem cell

Pulmonary adenocarcinoma exhibit different cell types that ultrastructurally, appear to be related to the different epithelial cell types occurring in the terminal lung lobule. The present paper describes the light-microscopical, ultrastructural and immunohistochemical features of a newly defined type of pulmonary adenocarcinoma that resembles an early stage of lung differentiation. The alternating epithelial differentiation within this tumour speaks in favour of a common endodermal stem cell for the different types of epithelial cells within the lung, including endocrine cells. The relationship of this tumour to pulmonary blastoma is discussed.

Shaping future strategies for the pharmacological control of tumor cell metastases

The eradication of established metastases in patients with malignant tumors is the single most important objective in clinical oncology. The current panel of antineoplastic agents discovered through random and semiempirical screening procedures has proven largely ineffective in treating disseminated disease and there is a clear and urgent need for more efficient antimetastatic drugs. Unfortunately, although progress has been made in examining the biology of metastatic spread, our understanding of the pharmacology, biochemistry and molecular genetics of this process is meager and insufficient to provide a rational foundation for the design of mechanism-based antineoplastic agents. Faced on the one hand with the failure of existing drugs to control metastatic spread and on the other with a dearth of alternative pharmacological approaches, the prospect of offering significantly improved therapy to the cancer patient of the 1990's is poor. The challenge of the coming decade lies in obtaining better insights into the molecular mechanisms of metastasis and using this information to identify pharmacological opportunities to curtail the proliferation of secondary tumor growths. As a first step toward this goal we need to define more rigorously what constitutes a therapeutic target in malignant disease and what steps in the pathogenesis of cancer metastasis represent the gravest risk to the patient and thus are most eligible for direct pharmacological intervention. In addressing these issues and developing future strategies for antimetastatic drugs, Paget's 100 year-old 'seed and soil' hypothesis continues to offer a useful conceptual framework for analysis of metastatic behavior. Although Paget's proposal has been validated by a century of clinical observation, efforts to define the 'seed and soil' theory in molecular terms have not been attempted. With the advent of more efficient methodologies for culturing human normal and neoplastic cells coupled with the availability of microanalytical technologies it now becomes possible to investigate and identify the complementary biochemical components of the tumor cell 'seed' and organ 'soil' that combine to encourage the proliferation of metastases. With this information the design of specific pharmacological strategies to uncouple the 'seed and soil' relationship may emerge as a potential therapeutic approach for antagonizing the growth of disseminated malignant tumors.