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Query: UMLS:C0149925 (small cell lung cancer)
 6,491 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously reported that a human small cell lung cancer (SCLC) cell line (COR L103) that expresses the proopiomelanocortin (POMC) gene and secretes ACTH precursor peptides is relatively resistant to glucocorticoid regulation. Using this model, we have now examined alternative regulatory mechanisms of the POMC gene and found that both the mRNA and ACTH precursor peptides were stimulated four- and two-fold, respectively, after 48 h incubation with db-cAMP. Next, we examined the dopamine agonist, bromocriptine, which acts predominantly through D2 receptors linked to adenyl cyclase to cause a reduction in intracellular cAMP. Bromocriptine suppressed cAMP levels and inhibited precursor peptide secretion within 24 h in a dose-dependent manner (0.15-15 microM). At the highest dose, peptide secretion was inhibited from 95 to 53 pmol/mg protein, and POMC mRNA was reduced by 50%, while beta-actin mRNA remained unchanged. This effect could not be mimicked by incubation of cells with the alpha-adrenergic antagonist, phenoxybenzamine, suggesting that the alpha-adrenergic effects of bromocriptine were not responsible for this observation. These cells also secrete estradiol, but the secretory rate was unaffected by bromocriptine, suggesting, with the beta-actin data, that the POMC inhibition was not a cytotoxic effect. No recovery in precursor peptide secretion was seen in a 48-h period after the removal of bromocriptine. However, when the postchallenge incubation was extended to 8 d, there was a recovery in secretory potential between day 3 and day 8 and normal growth kinetics in the 4 d after removal of the drug. In contrast to these findings, the mouse corticotroph cell line, AtT20, showed no response to bromocriptine, in keeping with reports that this agonist has no effect on anterior lobe corticotrophs. We conclude that bromocriptine effectively inhibits POMC expression in SCLC cells, and that this phenomenon might be of useful clinical application.
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PMID:Bromocriptine inhibits pro-opiomelanocortin mRNA and ACTH precursor secretion in small cell lung cancer cell lines. 132 94

A human small cell lung cancer cell line (COR L103) that actively expresses the proopiomelanocortin (POMC) gene has been used as a model of extrapituitary ACTH-secreting tumors to investigate the phenomenon of resistence of ACTH production to glucocorticoids. After both short term (24 h) and long term (10 days) exposure to hydrocortisone at concentrations of 500 and 1000 nM, the accumulation of intracellular POMC mRNA, ACTH, and ACTH precursor peptides in the culture medium was not suppressed. These finding contrast with those in the pituitary corticotroph cell line AtT20, in which POMC mRNA, ACTH, and ACTH precursors were suppressed under the same conditions. Two other genes that are regulated by glucocorticoids in other cell types, the tyrosine amino transferase gene and the glucocorticoid receptor gene, were expressed in COR L103 cells. However, neither gene appeared to be regulated by hydrocortisone in this small cell lung cancer cell line. Further studies demonstrated that glucocorticoid receptor binding could be detected in the nucleus and cytoplasm, with a Kd of 5 X 10(-9) M. It is concluded that nonsuppression of POMC by glucocorticoids is probably part of a more global defect of glucocorticoid signaling in these cells, but that this defect lies distal to steroid binding in the nucleus.
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PMID:Defective glucocorticoid regulation of proopiomelanocortin gene expression and peptide secretion in a small cell lung cancer cell line. 196 15

The molecular forms of ACTH secreted by established human small cell lung cancer (SCLC) cells and primary cultures derived from a bronchial carcinoid tumour, a pituitary adenoma and hyperplastic pituitary tissue have been characterized by Sephadex G-75 chromatography and quantified with two novel immunoradiometric assays for ACTH and ACTH precursor peptides. Pro-opiomelanocortin (POMC; Mr 31,000) and pro-ACTH (Mr 22,000) were secreted by all cell types. No smaller peptides were identified in the culture media from SCLC and bronchial carcinoid cells, implying a deficiency in the enzymes and/or intracellular organelles required for extensive POMC processing. A more heterogeneous profile of ACTH-containing peptides was produced by cells of pituitary origin, indicating more extensive proteolytic processing of POMC. However, the major peptide secreted by cells from a large aggressive pituitary adenoma was unprocessed POMC (Mr 31,000). These results suggest that both lung and pituitary cells in vitro retain their in-vivo pattern of POMC processing and provide valuable models in which to study the regulation of ACTH synthesis and secretion.
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PMID:Comparison of ACTH and ACTH precursor peptides secreted by human pituitary and lung tumour cells in vitro. 215 69

Small cell lung cancers are neuroendocrine tumours and therefore produce a lot of peptide hormones (calcitonin, ACTH, ADH), as well as the neuropeptide chromogranin A, which are all useful tumour markers. Furthermore, the tumour-associated antigens CEA and TPA, as well as the enzymes neuron specific enolase (NSE) and creatine kinase BB are used as markers in small cell lung cancer. At present, NSE appears to be the best marker for small cell lung cancer; elevated serum NSE levels are found in 65 to 85% of the patients. The serum level of the tumour markers is related to the stage of the tumour. When tumour regression occurs following therapy, elevated pretreatment levels decrease to the normal range. If the marker level increases again, tumour progression is indicated and this can be an early and sensitive sign denoting recurrence. Metastases in the central nervous system can be detected early by marker determination in the cerebrospinal fluid. At present, CEA appears to be the most valuable tumour marker for non-small cell lung cancer, but TPA may also be a useful marker.
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PMID:[Tumor markers in bronchus cancer]. 254 31

We investigated the production, binding to cell membranes, and influence on cell proliferation of peptides and growth factors in 4 classic, 5 transitional, and 5 variant SCLC cell lines. Glucagon, neurotensin, and TGF-alpha were present in all cell lines. Bombesin was predominantly found in classic cell lines and insulin in variant cell lines. Neurokinin A, calcitonin, CGRP, GHRF, somatostatin, and CNTF were detectable in some cell lines without prevalence for a particular cell type. We could not detect AVP, growth hormone, neuropeptide Y, substance P, VIP, and NGF. Insulin binding sites were present on 11/14 cell lines, and some cell lines specifically bound bombesin, calcitonin, and EGF. Growth effects were detectable for insulin, GRP-related peptides, tachykinins, and VIP. Using serum-free conditions, insulin and VIP had a growth stimulating effect in liquid culture at nanomolar concentrations. Bombesin and neuromedin B stimulated the clonal growth at a concentration of 3-30 nM. The tachykinins neurokinin A, neurokinin B, physalaemin, and eledoisin inhibited the clonal and mass culture growth with a peak effect in the range of 0.1 to 10 pM. Peptide-induced stimulating and inhibiting effects were within a magnitude of 2-fold. All other peptides and growth factors tested, including ACTH, AVP, calcitonin, glucagon, neurotensin, somatostatin, EGF, CNTF, and NGF did not affect the growth of SCLC. We conclude that the growth of SCLC is partly controlled by such peptides in an autocrine/paracrine fashion.
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PMID:Peptides and growth factors in small cell lung cancer: production, binding sites, and growth effects. 283 87

Creatine kinase (CK-BB), neuron specific enolase (NSE), ACTH, calcitonin, serotonin and gastrin releasing peptide (GRP) were measured in serum or plasma before and immediately after initiation of treatment in patients with small cell lung cancer (SCC). Pretherapeutic elevated concentrations of CK-BB were found in 82% of extensive disease patients and in 50% of patients with local disease. NSE was raised in 72% with extensive disease versus 14% of patients with local disease. Calcitonin and ACTH were raised in 27% and 28%, respectively, in all patients without significant difference between extensive and local disease patients. Serotonin was generally overall elevated in 10% and GRP in 7% but elevations were seen only in patients with extensive disease. Out of the four most frequently elevated substances at least one marker was elevated in 80% of all the patients, including 91% in extensive stage patients and 71% in limited stage patients. Frequent initial monitoring of the substances showed an increase in the concentrations of pretherapeutic elevated CK-BB and NSE on day 1 or 2 followed by a sharp decrease within 1 week. These changes were correlated to objective clinical response determined within 4-8 weeks. The results indicate that serum CK-BB and NSE are potential markers for SCC at the time of diagnosis and that changes in the concentrations during the first course of cytostatic therapy are promising as biochemical tests for early detection of response to chemotherapy.
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PMID:Early detection of response in small cell bronchogenic carcinoma by changes in serum concentrations of creatine kinase, neuron specific enolase, calcitonin, ACTH, serotonin and gastrin releasing peptide. 284 59

An immunoradiometric assay (IRMA) for the direct measurement of the precursors of ACTH in unextracted human plasma has been developed and evaluated clinically in normal subjects and patients with disorders of the hypothalamic-pituitary-adrenal axis. The IRMA is based on an iodinated monoclonal antibody to ACTH and a monoclonal antibody to gamma MSH coupled to Sephacryl S300. The assay detects only peptides containing both epitopes, i.e. POMC (31K) and pro-ACTH (22K). The reference standard was partially purified POMC from culture medium of human corticotroph adenoma cells. The detection limit (greater than +2.5SD of the 0 standard) was 2.0 pmol/L and the within-assay coefficient of variation was less than 10% between 29 and 2600 pmol/L. Plasma concentrations of ACTH precursor peptides in 11 normal subjects sampled at 0930 h ranged from 5-34 pmol/L. The concentrations in the patient groups studied were: 260-2300 pmol/L in 5 patients with the ectopic ACTH syndrome associated with small cell lung cancer, less than 2.0-104 pmol/L in 10 patients with pituitary-dependent Cushing's disease, 23 pmol/L in a patient with Nelson's syndrome, and 3.0-230 pmol/L in 5 patients with Addison's disease. We conclude that this IRMA offers a simple and reliable method for measuring ACTH precursors in unextracted plasma. The proportionately greater elevation of ACTH precursors compared to ACTH in patients with the ectopic ACTH syndrome associated with small cell lung cancer but not in pituitary-dependent Cushing's syndrome, suggests that this assay may be clinically useful.
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PMID:Direct measurement of the precursors of adrenocorticotropin in human plasma by two-site immunoradiometric assay. 284 55

The blood plasma levels of ACTH, CEA, calcitonin, parathyrin, hydrocortisone, serotonin, and histamine were measured radioimmunologically in 58 cases of small cell lung cancer prior to treatment. Elevated concentrations of CEA (61%) and ACTH (44%) were relatively frequent. Blood plasma--ACTH level in cases of expanded small cell lung cancer was higher than in healthy subjects and patients with localized tumor. A correlation was found between cancer patients survival time and the basal levels of CEA, ACTH and calcitonin. Polyamines were assayed in diurnal urine of 24 cancer patients prior to treatment and during chemotherapy. The mean level of putrescine before treatment was much in excess of normal value. Responders to treatment revealed a considerable rise in spermidine excretion within the first 10 days after treatment. In non-responders, spermidine excretion remained at the same level.
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PMID:[Biochemical methods and their place in prognosis and evaluation of the effectiveness of treatment of small cell lung cancer]. 299 83

A technique using 'tritiated thymidine suicide' has been established as a means of studying the response to cytotoxic drugs of cells at different depths within multicellular tumour spheroids. Because of the characteristic spatial arrangement of cycling cells (mostly in the outer regions) and non-cycling cells (mostly at the inner regions) of spheroids, cells surviving after long term (24 h) exposure of spheroids to high doses of 3HTdR will be those located furthest from the surface. By comparing the drug response of cells from 3HTdR pre-treated and untreated spheroids, the individual response of total cells, cells near to the surface and cells lying deeper within the viable rim of spheroids can therefore be deduced. In this study, large spheroids of about 800 micron in diameter of a mouse mammary cell line, EMT6/Ca/VJAC, and of a human small cell lung cancer cell line, POC, have been used. Using clonogenic assay, the response of these two cell types to adriamycin (ADM), nitrogen mustard (HN2), CCNU and vincristine (VCR) (POC only) were measured. The preliminary part of this study has confirmed that the cells killed are those which incorporate 3HTdR during the DNA synthesis period; the cells killed are mainly located in the outer regions of spheroids i.e. surviving cells are mostly located in the inner part of the viable rim and 3HTdR pretreatment does not sensitise surviving cells to subsequent cytotoxic drug treatment. Results from large EMT6 spheroids agree with our previous findings (obtained using a selective disaggregation method) that cells in the outer regions of spheroids are more sensitive to ADM and HN2 than cells in the inner regions whilst the opposite is true for CCNU. For POC spheroids, cells in the outer region of spheroids are more sensitive to ADM and VCR than cells in the inner region whilst a reverse trend is seen for the response to CCNU. The response to HN2 is similar at all depths. Amongst the factors governing the response of cells in spheroids to cytotoxic drugs, the responses to ADM and VCR are thought to be largely dictated by cell cycle distribution and limited drug penetrability, whilst for HN2 the response may be determined by the factor of cell cycle distribution. For CCNU, we believe that the cellular response is largely dependent upon microenvironmental factors prevailing within spheroids.
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PMID:Use of a tritiated thymidine suicide technique in the study of the cytotoxic drug response of cells located at different depths within multicellular spheroids. 303 19

Small cell carcinoma of the lung is the tumor most commonly associated with ectopic ACTH production and hypercortisolism. The relationship between this paraneoplastic endocrine syndrome and the clinical course of the tumor is examined in this review of patients with the ectopic ACTH syndrome and small cell carcinoma seen at The Johns Hopkins Oncology Center between 1973 and 1979. Five of 157 (3.2%) patients with small cell carcinoma were clinically diagnosed as having the ectopic ACTH syndrome. The onset of this endocrine syndrome appeared to coincide with a more aggressive phase of the course of small cell carcinoma. Further analysis of these cases suggests that the development of the ectopic ACTH syndrome may reflect changes in cell populations within the tumor and/or alterations in tumor behavior with time and perhaps with the effects of drug therapy.
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PMID:Ectopic adrenocorticotrophic (ACTH) syndrome and small cell carcinoma of the lung-assessment of clinical implications in patients on combination chemotherapy. 626 76


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