Secretion of a nerve growth factor by mouse neuroblastoma cells in culture

Sphingolipids as receptor modulators. An overview

Glycosphingolipids are amphipathic compounds that exist mainly in the plasmalemma with their oligosaccharide portion protruding into the extracellular environment. In this position they are admirably situated for interacting with both ligands and receptors. Binding studies have demonstrated that specific glycolipids function as receptors for some microorganisms and bacterial toxins. Specific oligosaccharides on both glycolipids and glycoproteins bind members of the selection families, and some gangliosides facilitate integrins binding to their ligands. Gangliosides modulate the trophic factor-stimulated dimerization, tyrosine phosphorylation, and subsequent signal transduction events of several tyrosine kinase receptors. GM3 inhibits both the epidermal growth factor receptor and basic fibroblast factor receptor; several gangliosides except GM3 inhibit the platelet-derived growth-factor receptor; GM1 enhances nerve growth-factor-stimulated activation of TrkA; insulin receptor is inhibited to varying degrees by several gangliosides, but 2-->3 sialosylparagloboside is most effective. Activities of the beta(1)-adrenergic and delta-opioid receptors are modulated by GM1. Available information suggests that glycolipids serve as coordinators of multiple receptor functions.

Induction of herpes simplex virus type 1 immediate-early gene expression by a cellular activity expressed in Vero and NB41A3 cells after growth arrest-release

Infected cell protein 0 (ICP0), a major immediate-early regulatory protein of herpes simplex virus type 1 (HSV-1), activates expression of all classes of HSV genes as well as a variety of heterologous viral and cellular genes. Previous studies have shown that a cellular activity expressed maximally in Vero cells 8 h after release from growth arrest in the G0/G1 phase of the cell cycle can enhance plaque formation and gene expression of a mutant virus (7134) lacking both copies of the gene encoding ICP0 (W. Cai and P. Schaffer, J. Virol. 65:4078-4090, 1991). This observation suggests that the cellular activity can substitute for ICP0 to activate viral gene expression. To further characterize this cellular activity, Vero and NB41A3 (mouse neuroblastoma) cells were transfected at various times after release from growth arrest with promoter-chloramphenicol acetyltransferase (CAT) constructs containing promoters representing the major kinetic classes of HSV genes, and CAT activity was measured from 2 to 24 h postrelease. The results of these tests demonstrate that CAT expression from immediate-early promoter-CAT plasmids was enhanced 10- and 3-fold when Vero and NB41A3 cells were transfected at 6 and 2 h postrelease, respectively. In contrast, only low levels of immediate-early promoter-driven CAT activity were apparent when cells were transfected at later times postrelease. No significant stimulation of CAT activity was observed from promoter-CAT plasmids containing representative early or late HSV promoters or a heterologous viral (simian virus 40 early) promoter. Differences in the efficiency of uptake of plasmid DNA by cells at various times postrelease did not account for the observed differences in CAT expression. Unlike Vero cells, in which cell division resumed after release from growth arrest, division of NB41A3 cells did not resume. Rather, these cells displayed morphological features suggestive of a differentiated phenotype. Collectively, these findings demonstrate that a cellular activity expressed in Vero and NB41A3 cells after release from growth arrest can activate HSV gene expression by enhancing immediate-early gene expression.

Nerve growth factor receptor expression in peripheral and central neuroectodermal tumors, other pediatric brain tumors, and during development of the adrenal gland

Nerve growth factor (NGF) is important to the survival, development, and differentiation of neurons. Its action is mediated by a specific cell surface transmembrane glycoprotein, nerve growth factor receptor (NGFR). In this study, NGFR expression by human fetal and adult adrenal medullary tissue, peripheral nervous system (PNS) neuroectodermal tumors (neuroblastoma, ganglioneuroblastoma, ganglioneuroma), pediatric primitive neuroectodermal tumors (PNETs) of the central nervous system (CNS), and CNS gliomas was examined by an immunohistochemical technique. Sixty-nine tumors in total were probed in this manner. Nerve growth factor receptor immunoreactivity was confined to nerve fibers and clusters of primitive-appearing cells in the fetal adrenal, and to nerve fibers and ganglion cells of the adult adrenal medulla; adrenal chromaffin cells were negative. In PNS neuroectodermal tumors, there was NGFR expression in tumor cells of 6 of 11 neuroblastomas and 6 of 6 ganglioneuroblastomas or ganglioneuromas. Thirteen of thirty-five CNS PNETs showed NGFR positivity. In most CNS PNETs, NGFR was restricted to scattered single or small groups of cells, but two tumors with astroglial differentiation showed much more extensive immunoreactivity. Most astrocytomas (11 of 14) and all ependymomas (3 of 3) were intensely NGFR positive.

Effect of nerve growth factor on C-1300 murine neuroblastoma tumor growth and catecholamine content in neonatally sympathectomized mice

The in situ C-1300 murine neuroblastoma (MNB) tumor model was used to investigate the influence of exogenously administered nerve growth factor (NGF) on tumor growth and tissue catecholamine concentration in mice sympathectomized with 6-hydroxy-dopamine (6-OHDA) on postnatal days 4-10. Mice were implanted with 1 x 10(6) disaggregated MNB cells 3 days after termination of 6-OHDA administration. NGF (12-15 micrograms/mouse/day) treatment was initiated at the time of MNB cell implantation and continued until sacrifice of the animal. The time interval between tumor cell implantation and detection of palpable tumor (tumor onset time), transverse tumor diameter, tumor weight, tumor weight to body weight ratio, and tumor catecholamine concentration were determined. Neonatal sympathectomy caused a decrease in myocardial norepinephrine concentration of 88% compared with vehicle-treated animals as well as a significant reduction in total body and organ weight. Average body, brain, heart, and spleen weights were decreased 31%, 16%, 25%, and 42%, respectively, below control values. The daily injection of NGF, from the time of MNB tumor implantation to sacrifice, did not prevent these effects of chemical sympathectomy from being expressed. Tumor onset time following implantation of MNB cells was significantly increased in neonatally sympathectomized mice and was not altered by treatment with NGF. In contrast, the decrease in MNB tumor growth rate observed in sympathectomized mice was reversed by administration of NGF. Mean tumor weight and mean tumor to body weight ratio were 89% and 115% of comparable control values, respectively, in sympathectomized mice receiving exogenous NGF.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth factors in human tumors

Various human tumor tissues contain different growth factors. In some cases progression of tumors is paralleled by elevated levels of these substances in blood or in tumor tissue. There is evidence that these growth promoting peptides might stimulate tumor growth. The growth of most tumors was associated with insulin-like substances (MW 45,000). We isolated and purified a substance immunologically cross-reactive with insulin (SICRI) from human melanoma. We found the molecular weight of affinity purified SICRI to be approximately 120,000. Our in vitro experiments with human renal carcinoma cells and growth factors suggest an important role of these molecules in tumor progression.

Gastric autonomic nerve (GAN) tumor and extra-adrenal paraganglioma in Carney's triad. A common origin

Carney's Triad comprises a triad of neoplasms: gastric stromal tumor, extra-adrenal paraganglioma (usually functional), and pulmonary chondroma. At least two of these are needed for the presumptive diagnosis of the Triad. This report presents a patient who had resected a gastric tumor and nonfunctional extra-adrenal paraganglioma. The gastric tumor resembled a gastric leiomyosarcoma by light microscopy, but electron microscopy revealed it to be a gastric autonomic nerve (GAN) tumor. Based on this evidence it appears that both the gastric lesions and the paragangliomata of Carney's Triad are tumors of the autonomic nervous system. Thus, the Triad may be a disorder of the autonomic nervous system rather than a multiple endocrine neoplasia syndrome or multiple hamartoma syndrome.

Nerve growth factor in medium conditioned by embryonic chicken heart cells

The present report demonstrates that embryonic chicken heart cells in culture release different nerve growth promoting factors to their culture medium, one which is biologically and immunologically similar to mouse gland beta NGF. Serum-free heart cell conditioned medium thus promoted neurite outgrowth from sympathetic and ciliary ganglia and supported survival of dissociated ciliary neurons. The addition of affinity purified antibodies against mouse beta NGF does substantially but not completely inhibit the fibre outgrowth from sympathetic ganglia, but does not to any extent diminish the effects on the parasympathetic neurons. The chicken NGF recovered from polyacrylamide gels after electrophoresis greatly enhanced sympathetic fibre outgrowth, an activity completely suppressive by anti-beta NGF antibodies. We conclude that a chicken NGF is being produced by the embryonic heart cells in culture, and that this factor may be produced also in the embryo to fulfill a role in heart innervation.

Nerve growth factor. A structural relationship between its proteolytic and leukocyte-chemotactic active sites

High molecular weight mouse nerve growth factor (HMW-NGF), in addition to its effects on certain neural elements, is also chemotactic for human polymorphonuclear leukocytes. One of the subunits of HMW-NGF is a protease of the serine family and its active site contains a serine residue and a closely-neighboring histidine residue that are both essential for proteolysis. Elimination of enzyme activity by irreversibly blocking the single serine has no effect on leukotaxis, but blocking the histidine abolishes leukotaxis. These results suggest the possibility that part of the proteolytic active site of this enzyme may have evolved to perform more than one, completely different, biologic function-proteolysis as well as nonproteolytically mediated chemotaxis.

Nerve growth factor synthesized by mouse fibroblast cells in culture: absence of alpha and gamma subunits

Nerve growth factor (NGF) is found in high concentrations in the mouse salivary gland. However, this gland is unique since salivary glands from other animals have only trace amounts of NGF. In the mouse gland, two high molecular weight forms of NGF have been reported, 7S-NGF [Varon, S., Nomura, J., & Shooter, E.M. (1967) Biochemistry 6, 2202-2209] and NGF1 [Young, M., Saide, J.D., Murphy, R.A., & Blanchard, M.H. (1978) Biochemistry 17, 1490-1498]. 7S-NGF is comprised of three noncovalently associated subunits: beta-NGF, which is the biologically active subunit, alpha subunit, and gamma subunit. A similar subunit composition is seen with NGF1 (unpublished work with R.A. Murphy). Since the mouse salivary gland is unique with regard to its synthesis of NGF, the following question arises. Do other sources of NGF produce either 7S-NGF or NGF1? Mouse fibroblast cells (L929) in culture synthesize and secrete into their feeding medium (conditioned medium) a beta-NGF-like molecule [Pantazis, N.J., Blanchard, M.H., Arnason, B.G.W., & Young, M. (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 1492-1496]. These cells therefore provided the opportunity to examine the molecular nature of NGF produced by a nonsalivary gland source. In this study, it was determined by radioimmunoassay that neither the alpha nor the gamma subunit is present in fibroblast cell conditioned medium. Since alpha- and gamma-proteins are present in both 7S-NGF and NGF1, this indicates that neither of the salivary gland forms of NGF are produced by the mouse fibroblast cell.

Nerve growth factor and neural oncology

The precise role of the nerve growth factor protein (NGF) during the growth and development of the human nervous system is not determined. Although it appears to influence a number of neural functions, its mechanism of action is poorly understood. A number of researchers have proposed that NGF may be involved in several pathological conditions including cancer. It has been shown that NGF is secreted by certain sarcoma (23), neuroblastoma (113), and glioma (7,102,136) cell lines and can bind to neuroblastoma and metastatic melanoma cell lines (42). Neuroblastoma (136,181) and pheochromocytoma (165) cells in vitro can be induced by NGF to differentiate toward a morphologically "more benign" state and appropriate NGF treatment of rats can reduce the number of chemically induced gliomas and neurinomas (174,178). NGF can also reduce the growth of intracerebrally inoculated anaplastic glioma cells (172). Anti-NGF treatment of rats (178) and mice (179) can alter the tumor distribution observed following ethylnitrosourea or benzo(a)pyrene treatment (10). In humans, it has been reported that serum levels of NGF are usually elevated in persons "at risk" for neurofibromatosis (156). The precise nature of the NGF role is not known in these instances. Further understanding of the action of NGF could be of clinical importance.

Protein-free medium for C-1300 mouse neuroblastoma cells

An optimized medium, designated MCDB 411, has been developed for mouse neuroblastoma cells. At cell densities of 1 x 10(4) cells/cm2 or greater, several different clones of C1300 mouse neuroblastoma cells can be cultured serially in Medium MCDB 411 with no serum or other undefined supplementation and with a doubling time of about 24 h. At clonal densities it is necessary to supplement the medium with 1.0 micrograms/ml insulin. Alternately, good clonal growth can be obtained without direct supplementation by coating the culture dishes with insulin and rinsing off all that is not tightly bound. Primary cultures of cells from serially transplanted C1300 tumors that have never been cultured previously in vitro can be established directly in unsupplemented Medium MCDB 411 with rapid initiation of multiplication and no apparent crisis or selection for minority cell types. The availability of a synthetic medium that supports growth of neuroblastoma cells without supplementation should facilitate the use of these cells as model systems for the study of neuronal function and differentiation.

Growth regulation by nerve growth factor

Although a great deal of descriptive information has been obtained about the actions of nerve growth factor on its target tissues, its structure, its receptors, and even its biosynthesis, there is no clear understanding, as yet, of the intracellular events mediating its transcriptional involvements. Work in this laboratory over the past five years has uncovered a number of nerve growth factor-initiated intracellular changes in sympathetic neurons and other nerve growth factor-sensitive systems, and has provided a framework into which they might fit. This article is written in an attempt to collect the data in a single communication and to suggest at least one mechanism by which the nerve growth factor may work.

Human melanoma cells have both nerve growth factor and nerve growth factor-specific receptors on their cell surfaces

Human melanoma cells were examined in an indirect membrane immunofluorescence assay for surface nerve growth factor (NGF) and NGF receptors. This assay revealed that human melanoma cells have various levels of NGF and NGF receptors on the plasma membrane, whereas a variety of human sarcoma and carcinoma tumor cells and normal human fibroblasts are negative. Surface NGF could be detected on melanoma cells with a rabbit antiserum directed to NGF at titers as high as 1:64; prior adsorption of this antibody with mouse 2.5S NGF resulted in a loss of fluorescence. The melanoma cells were positive whether or not they were grown in the presence of fetal calf serum. NGF production by human melanomas is a previously unrecognized property of this differentiated cell type. Although other cells in culture have been shown to produce NGF, the association of NGF production with the presence of NGF receptors on the cell surface is rare among tumor cells, and may represent an opportunity for "autostimulation" of melanoma cells by this growth factor.

Nerve growth factor: a protease that can activate plasminogen

The single, highly stable form of mouse submandibular gland nerve growth factor (NGF), prepared as described by Young et al. [(1978) Biochemistry 17, 1490--1498] is a protease of restricted specificity that can convert plasminogen to plasmin. In the absence of plasminogen, NGF is not fibrinolytic, nor does it hydrolyze casein at a measurable rate. Treatment of NGF with diisopropyl fluorophosphate inhibits its ability to activate plasminogen as well as its capacity to hydrolyze certain synthetic arginine esters. These results indicate that NGF is a member of the class of serine proteases. Since NGF is known to be secreted at high concentrations in mouse saliva, it may serve to activate plasminogen (with subsequent fibrinolysis) somewhere in the alimentary tract. Plasminogen activation is the only known action of NGF upon a biologically important non-neural substrate.

Synthesis and secretion of a high molecular weight form of nerve growth factor by skeletal muscle cells in culture

Rat skeletal muscle cells and a cloned myogenic cell line synthesize and secrete in culture a molecule that is immunologically and biologically indistinguishable from the active form of nerve growth factor (NGF) from mouse submandibular gland. This protein can be detected in medium conditioned by muscle cells both before and after fusion and in the soluble fraction of muscle cell homogenates. Chromatographic data also reveal that the molecular properties of muscle cell NGF differ from those of the growth factor purified from mouse submandibular glands. Muscle cell NGF has a molecular weight between 140,000 and 160,000, whereas purified mouse gland NGF has a molecular weight of 26,000. The biologic function of muscle cell NGF is not known, although it could be that it plays some role relating to the association of nerves and muscle in vivo.

Molecular properties of the nerve growth factor secreted in mouse saliva

Some molecular properties of the nerve growth factor (NGF) secreted in mouse saliva and that present in submandibular glands have been measured for comparison with previously studied forms of NGF. The results show that mouse saliva contains two biologically active NGF species. One has a molecular weight near 114,000, and the other, a molecular weight of 13,000. The larger form is being continuously degraded to yield the smaller one, probably as a result of a slow enzymatic process. Virtually identical results were obtained with crude submandibular gland extracts. The larger NGF is neither the well-known 7S NGF nor 2.5S NGF. Our results indicate that the larger salivary NGF is the naturally occurring form of NGF as it exists in the submandibular gland and as it is secreted in saliva. Its biological properties and its function in saliva, if any, remain to be elucidated.

Nerve growth factor in mouse serum and saliva: role of the submandibular gland

The concept that the salivary gland of the mouse is an endocrine organ for nerve growth factor (NGF) has been reexamined. Serum concentrations of the protein have been measured by radioimmunoassay in male and female mice and in mice from which the submandibular glands were removed. In spite of the fact that the submandibular glands of male mice contained more NGF than did those of female mice, no sex differences in circulating concentrations of the factor were detected. Furthermore, serum concentrations of NGF did not change after submandibular gland removal or after administration of several autonomic agonists. These results indicate that the submandibular glands are not endocrine organs with respect to NGF. On the other hand, extremely high concentrations of the factor are normally secreted in mouse saliva at levels that reflect the sex differences in the amount of NGF present in the glands. This finding suggests that the salivary gland is an exocrine organ for NGF and that the protein may play a biological role in saliva.

Calcitonin-responsive adenylate cyclase in a calcitonin-producing human cancer cell line

A calcitonin-responsive adenylate cyclase has been found in a cell line of a poorly differentiated bronchial carcinoma (BEN cells). The cells have previously been shown to secrete an immunoreactive form of calcitonin in culture. Salmon calcitonin (SCT), porcine calcitonin (PCT) and human calcitonin (CT-M) all stimulated adenylate cyclase activity in particulate preparations. CT-M sulphoxide had little effect. The concentrations of the calcitonins required for half the maximum activation of adenylate cyclase were 6-8, 18 and 90 nm respectively. SCT (30pm) and CT-M (60 pm) increased the intracellular concentration of cyclic AMP from 11-2+/-0-2 (s.e.) to 18-2+/-0-2 and 16-7+/-0-2 respectively over a 2-5-min period. SCT (labelled with 125I) bound to particulate preparations of Ben cells, and competition for binding occurred with unlabelled SCT and CT-M. The concentration of SCT required for half the maximum inhibition of [125I]SCT binding was 11 nm. CT-M sulphoxide inhibited only at high concentration (3 micron). The characteristics of the adenylate cyclase response to SCT did not change over the period between cell adhesion (after subculture) and confluence. However, pre-incubation of cells for 4 h with SCT (150 nm) abolished the subsequent adenylate cyclase response of particulate preparations to further hormone. The practical difficulties encountered in purifying and quantifying the large-mol.-wt. form of CT-M secreted by BEN cells has precluded direct investigation of the potential relationship between hormone secretion and the occurrence of the calcitonin receptor. This relationship is discussed in terms of its possible biological significance.

Dissociation of the 7S-nerve growth factor complex in solution

Sedimentation and gel-filtration studies of mouse submandibular gland 7S-nerve growth factor (NGF) reveal that this complex dissociates to yield its components at concentrations much higher than those required to exhibit biological activity. Results further indicate that the alpha and gamma protein c omponents of the 7S-NGF complex probably play no role in its biological activity when tested in vitro. The dissociation behavior of 7S-NGF is quite different from the properties of very dilute solutions of the NGF secreted by mouse L cells and of that present in fresh, unpurified submandibular gland homogenates, since both of these proteins display high molecular weights at concentrations where 7s-NGF is fully dissociated. Thus, it could be that 7S-NGF is not the form in which NGF exists in the mouse submandibular gland.

Molecular properties of the nerve growth factor secreted by L cells

The molecular size and stability of the nerve growth factor (NGF) secreted in culture by L cells have been studied by sedimentation and gel filtration chromatography. Results indicate that L cell NGF has a molecular weight of 160,000. It contains as part of its structure a protein component that is biologically, immunologically, and electrophoretically indistinguishable from the biologically active factor purified from mouse submandibular glands. However, unlike pure gland NGF, L cell NGF is highly stable in solution, and this finding indicates that L cell NGF is a form of the factor different from that previously described.

Secretion of nerve growth factor by central nervous system glioma cells in culture

Bacteriophage immunoassays, radioimmunoassays, and biological assays have been used to measure levels of NGF in media conditioned by rat C-6 glioma cells in culture. By all three criteria, these cells secrete a macromolecule which is indistinguishable from mouse submandibular gland NGF.

An 18,000 molecular weight polypeptide induces early events and stimulates DNA synthesis in cultured cells

Extracts of serum-free medium, conditioned by contact with SV40-transformed BHK cells, stimulate DNA synthesis in cultured fibroblasts. From this source, we have purified a homogenous basic protein of 18,000 molecular weight, termed fibroblast derived growth factor. In submicrogram quantities, fibroblast derived growth factor stimulates DNA synthesis in mouse 3T3 cells, in the absence of added serum. Prior to the onset of DNA synthesis, both serum and fibroblast derived growth factor induce an array of nearly simultaneous biochemical changes in the membrane to 3T3 cells that include stimulation of the uptake of nucleosides, 2-deoxyglucose, and 86Rb+. These results strongly suggest that the early events are integral components of the proliferative response, rather than coincidental effects of nonmitogenic molecules present in serum.