Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The study was concerned with the pathways of protein complexing in tumor growth. The effects of polyamines on blood plasma proteins and, particularly, on ribonuclease were investigated as a possible modifier of protein--protein interactions. In application of an ultrafiltration procedure, in vitro addition of polyamines to blood plasma imitated certain changes in plasma proteins which take place in tumor growth: filtrate showed a rise in the low molecular weight protein fraction, ribonuclease included. Peak concentrations of protein in filtrate were obtained virtually as soon as polyamines were added to incubation medium. The dissociating effect of polyamines was determined on the basis of the polyamine/protein ratio. Protein complexing was shown to be subject to the effects of both polyamines and products of their enzymatic oxidation.
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PMID:[Mechanisms of the effect of polyamines on the complex-forming ability of blood plasma ribonucleases]. 402 54

Tumor angiogenesis factor (TAF) and its importance in determining a strategy for cancer chemotherapy are discussed. It is suggested that inhibition of RNA synthesis or increased RNA catabolism might interfere with the metabolism of solid tumor cells more so than in normal cells, and thus hinder angiogenesis and pursuant tumor growth by preventing the synthesis of the RNA component of TAF. An attempt is made to indicate potential models for anti-angiogenesis agents of this type. The drugs offered as initial prototypes for investigations along these lines are actinomycin D (which likely has antimetabolite and anti-angiogenesis activities), polyriboinosinic-polyribocytidylic acid (which likely has adjuvant and anti-angiogenesis activities) and ribonuclease (which in theory might be a purely anti-angiogenetic agent). It is noted that these models may turn out to be less than ideal as therapeutic agents due to problems of toxicity, metabolism, potency, or distribution, but nonetheless might serve to yield insights into the design of new cancer chemotherapeutic drugs. In addition, some evidence is cited suggesting that actinomycin D may be more effective against certain tumors when employed in lower, chronic dosages rather than its present use in "loading" dosages.The concept of anti-angiogenesis agents as fundamentally "tumoristatic" therapies is discussed, and the likelihood that such agents might be effectively "tumoricidal" in immunocompetent hosts is mentioned. The main promise of an anti-angiogenetic strategy is efficacy against presently intractable slowly growing human cancers when used in combination with other treatment modalities. In summary, a strategy of cancer chemotherapy predicated upon interference with RNA synthesis or increase in RNA catabolism is offered as a potential mechanism for establishing anti-angiogenesis, and as a promising alternative and adjunct to present methods.
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PMID:Tumor angiogenesis factor. Speculations on an approach to cancer chemotherapy. 413 28

Our experiments were designed to determine whether recombinant ribonuclease inhibitor (RNasin) could inhibit angiogenesis and reduce tumor growth in adult mice. We used the Fajardo disc angiogenesis assay as the primary means of measuring new blood vessel growth. This assay measures the penetration of cells into a polyvinyl alcohol sponge with a central core of ELVAX-coated sponge containing test substances. Cell penetration was reduced to 29.3% of control (phosphate-buffered saline; heat-inactivated RNasin) values. Endothelial cell influx was measured by lectin staining and confirmed by culturing cells isolated from sponges by collagenase treatment. RNasin also reduced the augmented reaction evoked by either basic fibroblast growth factor (bFGF) or sodium orthovanadate. To confirm the anti-angiogenic activity of RNasin, Hydron-coated polyvinyl sponges containing bFGF or bFGF plus RNasin were implanted into adult mouse corneas. bFGF induced a strong angiogenic response that was almost completely inhibited by RNasin. RNasin-containing ELVAX-coated sponges implanted subcutaneously underneath an intradermal inoculum of C755 mammary tumor cells caused significant reduction in tumor growth (P < 0.005). The antitumor effect of RNasin correlated with its effect on tumor-induced neovascularization, suggesting that the ability of RNasin to affect tumor growth was due to its ability to inhibit angiogenesis.
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PMID:A ribonuclease inhibitor expresses anti-angiogenic properties and leads to reduced tumor growth in mice. 768 85

Bovine seminal ribonuclease (BS-RNase) is a homologue of RNase A with specific antitumor activities. It is selectively toxic for neuroblastoma (NB) cells in vitro with no significant effects on the viability of normal human cells. We evaluated the antitumoral effects of BS-RNase on human NB xenografts from UKF-NB-3 cells in athymic (nude) mice. The efficacy of direct intraneoplastic, subcutaneous and systemic delivery of BS-RNase was explored. Systemic administration of BS-RNase (12.5 mg/kg/day intraperitoneally, for 20 days in the course of four weeks) suppressed tumor growth but was not able to induce any cures. Subcutaneous injections (12.5 mg/kg/day for 20 days in the course of four weeks) and intratumoral BS-RNase treatment using the same schedule resulted in complete tumor regression. During 30 days following cessation of treatment no tumor regrowth was observed and animals were free of tumors. Toxic effects of BS-RNase (e.g., on bone marrow and inner organs) were not apparent. This data indicates that BS-RNase fulfills important criteria for a candidate antitumor agent specific for NB.
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PMID:Bovine seminal ribonuclease inhibits in vivo growth of human neuroblastoma cells. 1067 87

To evaluate the immunomodulatory effects of histamine in vivo, we analyzed an experimental syngenic tumor model using a colon adenocarcinoma cell line, CT-26, in Balb/c mice. In this model, distinct tumor growth was observed around 6 days after inoculation. Daily administration of cimetidine (0.12 mg/kg/day) significantly suppressed the increases in tumor volume and weight. On day 6 and day 7, histidine decarboxylase (HDC) activity was markedly increased. To examine the alterations in the local immune system, the cytokine expressions in the tumor tissue were measured by ribonuclease protection assay. The cytokine expression levels such as lymphotoxin-beta, tumor necrosis factor-alpha, interferon-gamma, interleukin-10, and interleukin-15 were considerably lower in tissues on day 14 than those on day 6. These decreased expressions were all restored by cimetidine. These results indicated that the effects of cimetidine on tumor growth in this model might be mediated by restoration of the decreased local cytokine expression, which exerts antitumoral effects.
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PMID:Effect of cimetidine on intratumoral cytokine expression in an experimental tumor. 1124 50

In an attempt to analyze the cellular and molecular basis of the capacity of bone marrow stromal cells to support hematopoiesis in culture, we developed a series of murine stromal cell lines from a single long-term bone marrow culture (BMC). The cytokines produced by these cells were analyzed using immunohistochemical techniques, ribonuclease protection assays (RPA) and RT-PCR. We examined the capacity of these cloned cell lines to replace primary bone marrow-derived stromal cells in long-term bone marrow cultures (LT-BMC) and sought correlations between the capacity to support hematopoiesis in culture with the production of known cytokines. These immortalized lines replicate many of the functions of the hematopoietic microenvironment. They express cytokines known to play a role in hematopoiesis. All of the lines constitutively express mRNA for PBSF (SDF-1), macrophage colony-stimulating factor (M-CSF), stem cell factor (SCF), FLT-3, thrombopoietin (TPO), interleukin 7 (IL-7), leukemia inhibitory factor (LIF), tumor necrosis factor-beta (TNF-beta), and interferon-gamma (IFN-gamma). Most lines also express granulocyte-macrophage colony-stimulating factor (GM-CSF) and G-CSF. They vary in their expression of IL-6, tumor growth factor-beta1 (TGF-beta1), TGF-beta2, and TNF-alpha. Growing these lines in the presence of cytokines that influence hematopoiesis alters the levels of cytokine message. The most striking effects were produced by TNF-alpha. In addition to the cytokine mRNAs, the cell lines express factors associated with bone formation such as osteoblast-specific factor-2 (OSF-2) and bone morphogenetic protein-1 (BMP-1). They also express the neural cell-adhesion molecule neuropilin and neurotrophic factors including nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). Several of the lines can maintain hematopoiesis in culture, as measured by the continuous production of myeloid colony-forming cells (CFU-c), for months. This capacity to support hematopoiesis does not correlate with any pattern of cytokine expression. Several of these lines also support the growth of human hematopoietic cells, and human CFU-c can be detected in the cultures in which CD34(+) bone marrow cells (BMC) are cultured on murine stromal cells. No correlation between the production of any of the known cytokines and the ability to support murine hematopoiesis was detected. In addition, there was no correlation between the capacity to support murine hematopoiesis and the capacity to maintain human HSC. Despite repeated cloning, the lines remain heterogeneous and are capable of producing cells with the properties of fibroblasts, osteoblasts, adipocytes, and myoblasts. In addition to the cytokine mRNAs, the cell lines express factors associated with bone formation such as OSF-2 and BMP-1. They also express the neural cell-adhesion molecule neuropilin and neurotrophic factors including NGF and BDNF.
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PMID:Immortalized multipotential mesenchymal cells and the hematopoietic microenvironment. 1127 66

The review is devoted to angiogenin, one of the factors that induce formation of blood vessels, which is unique among them in that it is a ribonuclease. Consideration is given to the tertiary structure of human angiogenin; the catalytic and cell-receptor binding sites, their significance for angiogenic activity; the human angiogenin gene structure, chromosomal localization, and expression; the specificity of angiogenin as a ribonuclease and abolishment of protein synthesis; the nuclear localization of angiogenin in proliferating endothelial cells and its significance for angiogenic activity; angiogenin binding to a cell-surface actin as a plausible mechanism of inducing neovascularization (enhancement of plasminogen activation by actin with angiogenin, stimulation of the cell-associated proteolytic activity by angiogenin; promotion of the cultured cells invasiveness); modulation of mitogenic stimuli in endothelial, smooth muscle, and fibroblast cells by angiogenin. The importance of angiogenin as an adhesive molecule for endothelial and tumor cells is discussed too, as well as the modulation of tubular morphogenesis by bovine angiogenin, prevention of tumor growth in vivo by angiogenin antagonists, prospects of the use of angiogenin and angiogenin-encoding recombinant plasmids and vaccinia virus in therapeutic practice.
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PMID:[Angiogenin and its role in angiogenesis]. 1144 14

The antitumor effect of ribonucleases was studied with animal ribonucleolytic enzymes, bovine pancreatic RNase A, bovine seminal RNase (BS-RNase), onconase and angiogenin. While bovine pancreatic RNase A exerts a minor antitumor effect, BS-RNase and onconase exert significant effects. Angiogenin, as RNase, works in an opposite way, it initiates vascularization of tumors and subsequent tumor growth. Ribonunclease inhibitors are not able to inhibit the antitumor effectiveness of BS-RNase or onconase. However, they do so in the case of pancreatic RNases. Conjugation of BS-RNase with antibodies against tumor antigens (preparation of immunotoxins) like the conjugation of the enzyme with polymers enhances the antitumor activity of the ribonuclease. After conjugation with polymers, the half-life of BS-RNase in blood is extended and its immunogenicity reduced. Recombinant RNases have the same functional activity as the native enzymes. The synthetic genes have also been modified, some of them with gene sequences typical for the BS-RNase parts. Recent experimental efforts are directed to the preparation of 'humanized antitumor ribonuclease' that would be structurally similar to human enzyme with minimal immunogenicity and side effects. The angiogenesis of tumors is attempted to be minimized by specific antibodies or anti-angiogenic substances.
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PMID:Ribonucleases and their antitumor activity. 1146 35

Previously, we designed a ribozyme that targets the H-ras oncogene at the 12th codon mutation site (Chang et al., 1997). Ribozymes have antisense molecule and site-specific ribonuclease potential. In this study, an adenoviral vector was used to transduce the H-ras ribozyme into laryngeal cancer cells (HEp-2). This served to downregulate the H-ras gene expression in which this ribozyme performed antisense activity due to HEp-2 cells containing wild-type alleles in the 12th H-ras codon. Together, our data demonstrated that the recombinant adenovirus encoding H-ras ribozyme can be broadly regarded as a cytotoxic gene therapy in laryngeal cancer cells regardless of containing wild-type or mutant ras gene. In addition, the mechanism through which the H-ras ribozyme inhibited tumor growth was apoptosis and involved both caspase- and mitochondria-mediated pathways. The activators caspase-8 and -9 as well as the effector caspase-3 in the induction phase of apoptosis and the substrate PARP of caspase-3 in the execution phase were activated 48h following the H-ras ribozyme treatment. Mitochondrial events characterized by the production of superoxide anion and the release of cytochrome c started at 24h. Mitochondrial transmembrane potential loss occurred 48h after the ribozyme treatment. However, Bcl-2 delayed cytochrome c release to the cytosol, but it could not protect the apoptosis effect, suggesting that cytochrome c release from mitochondria may not play a role in H-ras ribozyme-induced apoptosis.
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PMID:Recombinant adenovirus encoding H-ras ribozyme induces apoptosis in laryngeal cancer cells through caspase- and mitochondria-dependent pathways. 1241 27

Human ribonuclease inhibitor (RI) is a cytoplasmic acidic protein. The experiment demonstrated that it might effectively inhibit tumor-induced angiogenesis and inhibit tumor growth. Ribonuclease inhibitor is constructed almost entirely of leucine-rich repeats, which might be involved in unknown biological effects besides inhibiting RNase A and angiogenin activities. The exact molecular mechanism of antitumor on ribonuclease inhibitor remains unclear so far. In order to further understand the function of ribonuclease inhibitor and investigate the relationship with tumor growth, our study established a transfection of human ribonuclease inhibitor cDNA into the murine B16 cells by the retroviral packaging cell line PA317. The cell line transfected with a stably high expression of ribonuclease inhibitor was identified. We found that the transfected ribonuclease inhibitor could obviously inhibit cell proliferation, regulate cell cycle and induce cell apoptosis in vitro. Mice that were injected with the B16 cells transfected RI cDNA showed a significant inhibition of the tumor growth with lighter tumor weight, lower density of microvessels, longer latent periods, and survival time than those in the other two control groups. In conclusion, the results reveal the novel mechanism that antitumor effect of ribonuclease inhibitor is also associated with inducing apoptosis, regulating cell cycle and inhibiting proliferation besides antiangiogenesis. These results suggest that ribonuclease inhibitor might be a candidate of tumor suppressor gene in some tissues. RI could become a target gene for gene therapy. Our study may be of biological and clinical importance.
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PMID:Antitumor effects of human ribonuclease inhibitor gene transfected on B16 melanoma cells. 1577 86


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