Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ribonucleic acid was isolated from a wide spectrum of central nervous system tumors to examine the expression of platelet-derived growth factors (PDGF) A and B, tumor growth factors (TGF-beta) 1 and 2, and ros messenger ribonucleic acid. Eight glioblastoma cell lines were examined as well as cell cultures from 22 tumor explants. The explants included 6 glioblastomas, 4 anaplastic astrocytomas, 5 astrocytomas, 3 ependymal tumors, 2 meningiomas, 1 medulloblastoma. and 1 ganglioglioma. For comparison, 2 nontumor glial cell cultures were included. The PDGF B-chain was expressed in 5 of 8 glioblastoma cell lines, 2 of 6 glioblastomas, and in 3 of 4 anaplastic astrocytoma explants. There was no PDGF B expression in 4 astrocytomas, 3 ependymomas of varying malignancy, in the remainder of the tumors, or in the nontumor glial cells. The PDGF A-chain was expressed in all of the tumors, with the exception of the malignant ependymoma and in both nontumor glial cell cultures. TGF-beta 1 was expressed in all of the tumors and in nontumor glial cells. The expression of TGF-beta 2 was expressed in many of the benign and malignant tumors and also in both nontumor glial cell cultures. The ros messenger ribonucleic acid was expressed in 1 of 5 glioblastoma cell lines and in 2 of 6 glioblastoma cell explants, but in none of the other tumors or in the nontumor glial cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Expression of platelet-derived growth factors, transforming growth factors, and the ros gene in a variety of primary human brain tumors. 199 89

While many liver tumors contain activated myc and ras oncogenes, the mechanisms by which these genes contribute to cellular transformation is poorly understood. Activated versions of the cellular oncogenes, c-myc and/or c-H-ras were transfected into normal rat liver epithelial cells to identify cellular pathways that are altered in the cells containing the oncogenes. The results of these and other investigations indicate that the biological properties associated with the transfection of c-myc include immortalization, reduced contact inhibition of growth, activation of phospholipase A2-mediated pathways, increased sensitivity to transformation with a ras gene, and greatly increased sensitivity to growth factors. The biological properties associated with the transfection of the ras gene include morphological transformation, anchorage-independent growth, tumorigenicity, increased phosphatidylinositol metabolism, the induction of growth-factor processing and secretion, which leads to (exogenous) growth factor-independent tumor growth, and a marked resistance to normal inhibitors of growth such as TGF-beta. It is proposed that the complementary actions of the myc and ras genes in cellular transformation may be related to the ras-induced secretion of autocrine growth factors by cells sensitized to their effects by the myc gene. The increased stimulus for growth coupled to a ras-induced insensitivity to growth inhibitors may lead to clonal expansion of these cells and tumor development.
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PMID:Characterization of liver epithelial cells transfected with myc and/or ras oncogenes. 202 66

Phenobarbital (PB) added to the medium of cultured rat hepatocytes alters epidermal growth factor (EGF) dependent mitogenesis in a biphasic manner; PB concentrations less than 1.5 mM are growth stimulatory but higher concentrations significantly inhibit normal hepatocyte proliferation. In contrast, the growth of putative preneoplastic cells is inhibited less by high concentrations of PB. Mechanistic studies designed to test the ability of PB to alter the early events of EGF signal transduction demonstrate that PB neither competes with EGF for binding to the EGF receptor nor alters EGF-induced receptor down-regulation. However, pretreatment with PB (greater than 1 mM) results in a transient inhibition of EGF binding to hepatocytes. The kinetics of this effect are similar to those obtained when hepatocytes are exposed to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), a skin tumor promoter and activator of Ca2+/phospholipid-dependent protein kinase C. However, several observations suggest that distinct mechanisms mediate the responses to these two tumor promoters. First, the inhibitory effects of PB and TPA on EGF binding are additive. Also down-regulation of EGF receptors in response to TPA occurs with hepatocytes, A431 epidermal carcinoma cells, HepG2 hepatoma cells, and rat liver epithelial cells, but only hepatocytes are sensitive to PB. Furthermore, translocation of protein kinase C to the membrane occurs in hepatocytes treated with TPA but not in those treated with PB. The chronic treatment of rats with PB further sensitizes hepatocytes to EGF receptor down-regulation by in vitro PB while desensitizing them to EGF receptor down-regulation by TPA. This latter effect is correlated with a decreased ability of TPA to induce translocation of protein kinase C to the membrane. PB significantly increases the intracellular concentration of TGF-beta 1 in periportal hepatocytes but not in putative preneoplastic cells. TGF-beta 1 may therefore have an important function in regulating early stages of cell cycle progression in proliferating hepatocytes.
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PMID:Liver tumor promotion: effect of phenobarbital on EGF and protein kinase C signal transduction and transforming growth factor-beta 1 expression. 202 68

A cell line, designated HAL-01, was established from the blood cells of a patient with acute lymphoblastic leukemia (ALL) with a myeloid-associated marker. Both the cell line and the patient's fresh leukemia cells had the chromosomal translocation t(17;19)(q21;p13). Morphologically and cytochemically, the cells were lymphoid in appearance. Immunophenotyping of the donor's leukemia cells revealed that they express B lineage antigens (CD10+, CD19+, CD20+, CD22+); the myeloid-associated antigen (CD13) detected in the donor's leukemia cells was not expressed by the established cell line. The HAL-01 cells have a rearrangement of the immunoglobulin heavy chain gene, while the T-cell receptor beta-chain genes remain in the germline configuration. The gene encoding the binding proteins for the kappa-light chain enhancer (kappa E2), which is involved in pre-B-ALL cells with the t(1;19) (q23;p13) translocation, is not rearranged in the cell line. The HAL-01 cells were transplantable into the peritoneum of untreated nude mice where they grew as an ascites tumor. The growing tumor cells also infiltrated lymph nodes, liver, spleen, kidney, and bone marrow without exhibiting a particular change in the morphology of the neoplastic cells. Clonogenic assay in methylcellulose culture demonstrated that the proliferation of the HAL-01 cells was suppressed by interleukin-3 (IL-3) in a dose-dependent fashion, with maximum inhibition occurring at concentrations greater than 100 U/ml. Treatment with IL-3 reduced the number of viable cells as well as induced morphological changes without concomitant changes in cytochemical reactions or immunophenotypic expression. Reduction of 3H-thymidine incorporation by exposure of IL-3 was blocked by the pretreatment of neutralizing anti-IL-3 antibody, but not by neutralizing anti-TGF-beta antibody. Thus, HAL-01 is a unique ALL cell line exhibiting proliferative suppression by IL-3 that may prove useful in studying the interactions of cytokines in ALL.
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PMID:Establishment of a novel heterotransplantable acute lymphoblastic leukemia cell line with a t(17;19) chromosomal translocation the growth of which is inhibited by interleukin-3. 202 99

While stimulating the growth of fibroblasts, transforming growth factor beta 1 (TGF-beta 1) inhibits the growth of various normal and malignant cell lines in vitro. We studied the effects of TGF-beta 1 in vivo. The level of TGF-beta 1 in serum was maximally elevated 2 h after injecting 1 muCi of 125I-TGF-beta 1 into the peritoneal cavity of nude mice. Five h after the i.p. administration of 10 micrograms of unlabeled TGF-beta 1, 20 ng/ml of TGF-beta-like material in serum were detected by a radioreceptor assay on A549 lung carcinoma cells. Trichloracetic acid-precipitable 125I-TGF-beta 1 was taken up by liver, spleen, lungs, kidneys, and tumor tissue but not by the brain. At doses exceeding 2 micrograms/day, TGF-beta 1 induced a generalized interstitial fibrosis and a cachexia, which was not mediated by elevated serum levels of tumor necrosis factor alpha as determined by Western blot analysis and enzyme-linked immunosorbent assay. A total of 200,000 cells of the estrogen receptor-negative human breast cancer line MDA-MB-231, which had been shown to be maximally growth inhibited in vitro by 40 pM TGF-beta 1 and to have high-affinity receptors (9, 11, 12), were injected into the mammary fat pad of each nude mouse. The duration of treatment was 16 days with ten animals in the control group and five animals in the treated groups. The dose ranged from 1 to 4 micrograms per animal daily. The treatment was started 24 h after the injection of the tumor cells. Tumor growth was not significantly affected at either nontoxic or toxic doses of TGF-beta 1. Thus, we have demonstrated that TGF-beta 1, apart from being a local growth factor, has systemic effects, such as cachexia and multiple fibrosis. Its role as an antitumor agent may be limited.
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PMID:Transforming growth factor beta 1 induces cachexia and systemic fibrosis without an antitumor effect in nude mice. 205 95

The data presented above suggest that one possible clinical use of TGF-beta would be to protect the bone marrow from the effects of myelosuppressive chemotherapeutic drugs by preventing entry or removing primitive stem cells from the cell cycle. It may also have the additional benefit of reducing the drug-induced neutrophil nadir by stimulating granulopoiesis. The availability of large quantities of recombinant TGF-beta will allow study of the pharmacokinetics with different routes of administration, dosage effects, and details of the pleiotropic effects on other cell systems. Experiments are in progress to determine whether TGF-beta will allow the delivery of higher amounts or more frequent doses of chemotherapeutic drugs and thus allow increased antitumor efficacy in tumor-bearing animals.
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PMID:Role of transforming growth factor-beta 1 in regulation of hematopoiesis. 206 10

Transforming growth factor-beta s (TGF-beta s) are potent regulators of cell growth and differentiation. Expression of the closely related TGF-beta subtypes in vivo is differentially regulated both temporally and spatially. Members of the steroid hormone superfamily may play an important role in this gene- and tissue-specific regulation. We have shown that anti-estrogens induce the production of TGF-beta 1 in mammary carcinoma cells and fetal fibroblasts, whereas retinoic acid specifically induces TGF-beta 2 in primary epidermal keratinocytes. The induction of TGF-beta 2 by retinoids is accompanied by an increase in TGF-beta 2 mRNAs, but little change in transcription rates, suggesting an effect of retinoids on message stability or processing. In contrast, TGF-beta 1 mRNA levels are unchanged by anti-estrogen treatment, suggesting these compounds may regulate the translatability of the TGF-beta 1 message or some post-translational processing event. We have identified a stable stem-loop structure in the 5' untranslated region (UTR) of the TGF-beta 1 mRNA that inhibits translation of a heterologous reporter gene, and we are investigating the possibility that anti-estrogens may regulate the activity of this element, and hence the translatability of the TGF-beta 1 message. A significant fraction (25-90%) of the TGF-beta induced by retinoids and anti-estrogens is in the biologically active rather than the latent form. We have shown that active TGF-beta has a much shorter in vivo half-life than latent TGF-beta, suggesting that the TGF-beta induced by retinoids and steroids may act locally at the site of production. Since many tumor cells retain sensitivity to the growth inhibitory effects of active TGF-beta, the use of members of the steroid hormone superfamily for inducing this potent growth inhibitor locally at the tumor site may have therapeutic potential.
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PMID:Regulation of transforming growth factor-beta subtypes by members of the steroid hormone superfamily. 208 13

Human esophageal and gastric carcinomas express multi-autocrine growth factors and hormones including epidermal growth factor (EGF), transforming growth factor (TGF)-alpha and beta, platelet-derived growth factor (PDGF), insulin-like growth factor (IGF) and sex hormones. Overexpression of EGF, TGF-alpha and EGF receptor (EGFR) by tumor cells is closely correlated with the tumor invasion and patient prognosis. This is substantiated by the facts that EGF and TGF-alpha act as autocrine growth factors and then induce the expression of mRNAs for multi-growth factors and their receptors (EGF, TGF-alpha, EGFR, ERBB2, PDGF). Moreover, they stimulate the expression of metalloproteinase genes suggesting that EGF and TGF-alpha successively evoke cascade phenomena which are most convenient for tumor progression, invasion and metastasis. On the other hand, multiple oncogene alterations take place in the process of tumor progression. HST-1 and INT-2 genes which is a member of fibroblast growth factor gene family, are amplified in approximately 50% of primary tumors and all the metastatic tumors of esophageal carcinomas. The amplification of ERBB2 gene in metastatic gastric carcinomas is detected more frequently than in primary carcinomas. Overexpression of multi-growth factor-receptor systems might lead to genetical alterations. Scirrhous gastric carcinoma has vast fibrous stroma with rapid and extensive growth and exhibits high malignancy. Its fibrous stroma may account for synchronous overexpression of EGF, TGF-alpha, PDGF, IGF and TGF-beta by tumor cells. Most of well differentiated adenocarcinomas show overexpression of p 185ERBB2 and coexpression of p 185ERBB2, and EGFR evidently correlates with high malignancy. In conclusion, the accumulation and interaction of several growth factors produced by tumor cells are necessary for the progression of human esophageal and gastric carcinomas. They may be attributed to genetic changes including activation of oncogenes, inactivation and deletion of anti-oncogenes and transcriptional regulatory sequences.
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PMID:Growth factors in progression of human esophageal and gastric carcinomas. 209 74

In the process of malignant transformation, astrocytoma cells display a number of surface antigens not expressed by their normal adult counterparts and which have been identified by monoclonal antibodies and characterized biochemically. These include tumor associated antigens (TAA) such as oncofetal antigens of neuroectodermal origin or oncogene products such as epitopes in the extracellular domain of the epidermal growth factor receptor, as well as major histocompatibility antigens (MHC) of class I and class II. Glioma cells also secrete lymphokines like IL-1 and IL-6. The concomitant expression of TAA and MHC together with the disruption of the blood brain barrier may elicit a humoral or cell mediated immune response from the tumor bearing host as demonstrated by the functional analysis of tumor infiltrating lymphocytes. However this response is extremely weak and obviously inefficient because the tumor cells secrete factors which can inhibit or completely abrogate the immune attack by cytotoxic T cells. Among these factors, TGF-beta 2 and PGE2 are of particular interest since they may explain the generally depressed cellular immune response observed in patients with malignant gliomas. To be efficient any form of immunotherapy will require abatement of these suppressive activities in addition to stimulation of the effector functions.
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PMID:Immunotherapy of brain tumors. 209 5

Macrophage deactivation factor (MDF) in P815 tumor cell-conditioned medium was assayed by its suppression of the ability of activated mouse peritoneal macrophages to release hydrogen peroxide. MDF displayed properties of a soluble protein(s) associated with both low (8-25,000) and high (greater than 450,000) Mr fractions. MDF was purified 6,140-fold by a seven-step procedure: extraction with acid-ethanol; precipitation with ether; and fractionation on gel filtration, anion-exchange, diphenyl reversed-phase and C4 reversed-phase HPLC columns, the last column twice. The final preparation contained two species: (a) a approximately 13,000 Mr band on reducing or nonreducing SDS-PAGE and on autoradiograms after radioiodination with chloramine T, and (b) a 66,000 Mr species ranging from approximately 5% to approximately 50% of the protein detectable by silver strain. The 66,000 Mr species was identified as albumin from its NH2-terminal amino acid sequence. However, no amino acid sequence could be obtained for the approximately 13,000 Mr species, either in fluid phase or after electroelution of the corresponding SDS-PAGE band. Thus, approximately 13,000 Mr MDF associates tightly with albumin through a variety of separation techniques, and may have a blocked NH2 terminus. Purified MDF afforded 50% inhibition of activated macrophage H2O2 releasing capacity at a concentration of 1-10 nM. Separation of MDF from most higher Mr moieties was associated with disproportionately small increases in specific activity, suggesting MDF might be partially inactivated by purification. As purified, MDF was approximately 1,000-fold less potent at deactivating macrophages than TGF-beta. Antibodies that neutralized the macrophage-deactivating effect of TGF-beta did not inhibit deactivation by MDF.
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PMID:Purification of macrophage deactivating factor. 210 38


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