calcimycin and Carcinoma--Small-Cell

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Adenocarcinoma; Calcimycin; Carcinoma, Small Cell; Carcinoma, Squamous Cell; Cell Communication; Cell Line; Coculture Techniques; Erythrocytes; Humans; Hydroxyeicosatetraenoic Acids; Leukotriene B4; Lung Neoplasms; Models, Biological; Neutrophils; Phospholipases A; Phospholipases A2; Tumor Cells, Cultured

Although atrial distension is widely accepted as the primary stimulus for atrial natriuretic peptide (ANP) release, a number of agonists are also known to induce its secretion. The mechanisms underlying these processes are not well understood. Studies of this nature are hampered by the inherent difficulty in culturing homogeneous populations of cardiac myocytes in sufficient quantities to perform molecular investigations. For this reason, we have examined the possibility of using other cell types as a model of ANP release. It has been reported that a number of tumor samples from small cell lung cancer (SCLC) patients express the ANP gene. Characterization of a large number of cell lines derived from SCLC tumor samples indicated that two of these cell lines, OS-A and SHP-77, secrete ANP at rates of approximately 10(-20) g.cell-1.min-1. This is a sufficient quantity to facilitate secretion studies using a perifusion system. We have demonstrated that ANP is released through regulated secretory pathways, as the Ca2+ ionophore A-23187, arginine vasopressin (AVP), and the sodium ionophore, monensin, were capable of modifying secretion rates. High-pressure liquid chromatography (HPLC) analysis indicated that the primary secretory product is ANP-(99-126), the circulating form of this hormone. Intracellularly, both ANP-(99-126) and ANP-(1-126) were present, suggesting the synthesis and appropriate cleavage of pro-ANP-(1-126). Because both of these cell lines have doubling times in the range of 3-5 days, they could serve as a rapidly proliferating and easily maintainable supply of homogeneous tissue for release studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Arginine Vasopressin; Atrial Natriuretic Factor; Calcimycin; Carcinoma, Small Cell; Chromatography, High Pressure Liquid; Humans; Molecular Structure; Time Factors; Tumor Cells, Cultured

The mechanism of ectopic adrenocorticotrophic hormone (ACTH) secretion was examined by studies on the effects of corticotropin-releasing hormone (CRH), dexamethasone, interleukin (IL)-1 beta and 2, somatostatin, calcium ionophore A23187, 12-O-tetradecanoylphorbol-13-acetate (TPA) and 8-bromo-cAMP on pro-opiomelanocortin (POMC) expression and ACTH secretion from a human small cell lung cancer cell line COR-L103. None of these agents except TPA and A23187 had any effect on ACTH secretion from the cell line in short (0-8 hrs) or long term (1-4 days) cultures. In long term cultures, 1-100 nM TPA stimulated ACTH secretion dose-dependently, whereas 500nM A23187 inhibited ACTH secretion completely. When the cells were incubated with 10nM TPA plus 500 nM A23187, the inhibitory action of A23187 on ACTH secretion was suppressed by TPA. These results suggest that the mechanisms of ACTH secretion by COR-L103 cells and normal pituitary cells are different.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Adrenocorticotropic Hormone; Calcimycin; Carcinoma, Small Cell; Cell Line; Corticotropin-Releasing Hormone; Dexamethasone; Dose-Response Relationship, Drug; Humans; Immunoradiometric Assay; Interleukin-1; Interleukin-2; Kinetics; Lung Neoplasms; Pro-Opiomelanocortin; Somatostatin; Tetradecanoylphorbol Acetate; Time Factors; Tumor Cells, Cultured

Four classical and three variant small-cell carcinoma of the lung (SCCL) cell lines were examined for vasopressin and vasopressin V1a-receptor immunoreactivity. One of these classical cell lines, NCI-H345, and one variant cell line, NCI-H82, were further investigated for binding of V1 and V2 vasopressin-receptor antagonists, vasopressin-induced calcium mobilization, and vasopressin-induced thymidine uptake. All classical and variant SCCL cell lines examined contained vasopressin and vasopressin-receptors as determined by immunocytochemistry. Both NCI-H82 and NCI-H345 demonstrated similar binding patterns with the V1 and V2 vasopressin-receptor antagonists, indicating the presence of both receptor subtypes. For the classical cell line (NCI-H345), vasopressin (1 microM) induced an increase in cytosolic free calcium, while the peptide was ineffective at increasing cytosolic calcium in the variant cell line (NCI-H82). However, vasopressin (0.1 or 1 microM) was unable to stimulate thymidine uptake in the classical (NCI-H345) or variant (NCI-H82) cell lines for the conditions used. These results indicate that both classical and variant SCCL produce vasopressin, and vasopressin V1a and V2 receptors. In the variant cell line, there appears to be a disruption in the activation cascade for V1a receptors as indicated by the lack of vasopressin-induced calcium mobilization.

Topics: Calcimycin; Calcium; Carcinoma, Small Cell; Cytosol; Humans; Lung Neoplasms; Receptors, Vasopressin; Thymidine; Tumor Cells, Cultured; Vasopressins

Very little has been known of the biochemical function of a human adrenocortical carcinoma cell line, SW-13. In this study, the production of several adrenal steroids and 3', 5'-cyclic adenosine monophosphate (cAMP) were investigated in this cell line. The cells were incubated in L-15 medium containing 0.1% bovine serum albumin with several reagents in an atmosphere of 5% CO2 and 95% air for 2 hours at 37 degrees C. Aldosterone (Ald), corticosterone (B), cortisol (F), dehydroepiandrosterone sulfate (DHEA-S) and cAMP were simultaneously assayed by specific radioimmunoassays in the medium and cells. Significant increases in cAMP production were observed by cholera toxin (10 ng/ml) and forskolin (10 nM), both direct stimulators of adenylate cyclase, in the cAMP concentration without an increase in the steroids. The DHEA-S concentration in the medium was significantly increased by angiotensin-II (10(-7)M), noradrenalin (3 X 10(-5) M), adrenalin (3 X 10(-5) M) or alpha-melanocyte-stimulating hormone (alpha-MSH, 10(-7) M), none of which was associated with cAMP production. Neither adrenocorticotropin (10(-10) M) nor human chorionic gonadotropin (500 mIU/ml) stimulated the release of the steroids or cAMP production. A calcium ionophore, A23187 (10(-7) M), and 12-O-tetradecanoylphorbol-13-acetate (10(-8) M), a direct stimulator of protein kinase C, stimulated the release of DHEA-S, but not those of Ald, B and F. The results suggest that SW-13 retains functioning adenylate cyclase which, however, is not linked with steroidogenesis and that DHEA-S is produced probably by the mechanisms which involve protein kinase C system or calcium ion. This report provides the first demonstration of cAMP and DHEA-S production in SW-13 and suggests that this cell line is potentially useful for investigating the mechanisms of steroidogenesis in the human adrenal cortex.

Topics: Adrenal Cortex Neoplasms; Adrenocorticotropic Hormone; alpha-MSH; Angiotensin II; Calcimycin; Carcinoma, Small Cell; Cell Line; Cholera Toxin; Chorionic Gonadotropin; Colforsin; Cyclic AMP; Dehydroepiandrosterone; Dehydroepiandrosterone Sulfate; Epinephrine; Humans; Norepinephrine; Tumor Cells, Cultured

The metabolism of arachidonic acid (AA) was studied in two pulmonary bronchioloalveolar-carcinoma cell lines (NCI-H322 and NCI-H358) and two small cell lung carcinoma cell lines (NCI-H69 and NCI-H128). Exogenous AA was metabolized only in the NCI-H322 and NCI-H358 cells. There was no detectable metabolism of AA in NCI-H69 or NCI-H128 cells, either in the presence or the absence of the calcium ionophore A23187. The major metabolite of AA isolated from both NCI-H322 and NCI-H358 cells was prostaglandin E2 (PGE2). Prostaglandin endoperoxide synthase activities, expressed as immunoreactive PGE2 (pmol/min/mg protein), were 10.3 +/- 0.28 (SD) and 4.8 +/- 0.48 in NCI-H358 and NCI-H322 cells, respectively. The rate of production of PGE2 by both NCI-H358 and NCI-H322 cells was linear up to 10 min. Production of PGE2 in both cell lines was dependent upon substrate concentration and was maximal above 17 microM AA. Moreover, PGE2 did not undergo further metabolism by either the NCI-H358 or the NCI-H322 cells. Aspirin (0.1 mM), a cyclooxygenase inhibitor, decreased PGE2 production by 77 and 60% in NCI-H358 and NCI-H322 cells, respectively. In the presence of exogenous AA the calcium ionophore, A23187 (20 microM), stimulated PGE2 production in NCI-H322 cells by almost 2-fold, although it did not affect PGE2 production in the NCI-H358 cells. In contrast, A23187 stimulated the endogenous production of PGE2 in both NCI-H322 and NCI-H358 cells by 4- and 9-fold respectively. In addition, both the NCI-H358 and NCI-H322 cell lines were susceptible to the cytotoxic effects of the anticancer agent mitoxantrone in both a time and concentration dependent manner. In contrast, the two cell lines lacking detectable prostaglandin synthesis activity, NCI-H69 and NCI-H128 were unaffected by treatment with mitoxantrone. These results illustrate that there are major differences in the abilities of human lung cancer cell lines to biosynthesize and release PGE2. It is conceivable that such differences might have exploitable diagnostic and/or therapeutic implications.

Topics: Adenocarcinoma, Bronchiolo-Alveolar; Arachidonic Acid; Arachidonic Acids; Aspirin; Calcimycin; Carcinoma, Small Cell; Cell Line; Dinoprostone; Dose-Response Relationship, Drug; Humans; Lung Neoplasms; Mitoxantrone; Prostaglandins E; Time Factors