Landschutz Ascites Tumour Cells Research Articles

Effects of coumarins, haematoporphyrins and acridine orange on the viability and growth of Landshütz ascites tumour cells, in the presence and absence of photoradiation

The effects of haematoporphyrin (Hp), haematoporphyrin derivative (HpD), coumarin, 7-hydroxycoumarin, 4-hydroxycoumarin, amino-methyl-coumarin acetic acid and acridine orange, with and without photoradiation, on Landschutz ascites tumour (LAT) cells were examined. Hp, HpD and acridine orange showed a significant effect on LAT cell viability following photoradiation. However, coumarin or its derivatives had no significant effect on LAT cell viability, with or without photoradiation, over 18 h. Coumarin alone had a significant effect on viability of LAT cells, in vitro, over a period of 9 days. This effect was verified by transplantability studies. Coumarin and 7-hydroxycoumarin both exhibited cytostatic effects on LAT cell growth.

The production and characterization of monoclonal antibodies to Landschutz ascites tumour cells

The production and characterization of monoclonal antibodies to Landschutz ascites tumour cells

Liberation of cholesterol from cells by proteolytic enzymes.

EXPOSURE of Landschutz ascites tumour cells to the proteolytic enzymes trypsin or brinase was found to cause release of small but statistically significant amounts of cholesterol into the medium. Since treatment with these enzymes also increases the agglutinability of the cells towards specific antiserum, it is suggested that cholesterol loss may be among the membrane changes involved in this enhanced aggultinability

Control of RNA synthesis by amino acids in Landschutz ascites tumor cells.

Landschutz cells incubated in amino acid-deficient medium for 2.5 h show a markedly reduced incorporation of [3H]uridine into 18 S and 28 S cytoplasmic ribosomal RNA (rRNA) and into 28 S, 32 S, and 36 S nuclear RNA measured during the last 90 min of incubation, whereas the radioactivity associated with 45 S pre-rRNA is not affected. Ten-minute pulse-labeling and 15-min pulse-chase experiments show that amino acid starvation inhibits both the synthesis and processing of 45 S pre-rRNA. Amino acid starvation has no significant effect on the labeling of the nucleotide pools. This effect of amino acids was specific for rRNA since the synthesis of 4 S and 5 S cytoplasmic RNA separated on polyacrylamide gels and of polysomal mRNA analyzed on sucrose gradients was not significantly affected during amino acid starvation. These data also indicate that RNA synthesis is non-coordinated in Landschutz cells. Among the 13 amino acids essential for growth of these cells, arginine and glutamine appear to be mainly responsible for the inhibition of synthesis of 18 S and 28 S rRNA measured during incubation in complete amino acid-deficient medium. The removal of any one of the other amino acids has a small inhibitory effect on the incorporation of [3H]uridine into rRNA and their effect on the synthesis of 18 S rRNA is more pronounced than on that of 28 S rRNA. Such effect results in an unbalanced production of these two ribosomal RNA species.

Proceedings: Concanavalin A (con A) induced redistribution of surface receptors on Land-Schutz ascites tumour (LAT) cells and its inhibition by glutaraldehyde prefixation and low temperature.

Proceedings: Concanavalin A (con A) induced redistribution of surface receptors on Land-Schutz ascites tumour (LAT) cells and its inhibition by glutaraldehyde prefixation and low temperature

Studies on a naturally occurring human antibody active against mouse Landschutz ascites tumor cells. 3. The nature of the antigenic site on the tumor cell.

AbstractGalactose and galactose‐containing sugars were found to have an inhibitory effect on the cytotoxic and agglutinating activity of human serum against Landschutz ascites tumor cells. This suggested that D‐galactose may be an essential part of the tumor cell antigenic site involved.The pattern of inhibition by the various sugars resembled that of the human blood group B system. However, absorption experiments showed that, while the mouse tumor cells had sites which bind anti‐B, the latter was different from the cytotoxic antibody, and did not participate significantly in the cytotoxic reaction.From the differing patterns of sugar inhibition for sera of the various human blood groups, there were indications that the cytotoxic activity may be due to a group of antibodies of slightly differing sugar specificities.The cytotoxic agent could be absorbed by heat‐killed ascites tumor cells and eluted thereafter, using certain galactose‐containing sugars as eluting agents. These experiments confirmed the hapten‐like nature of D‐galactose in this system.Sugar and non‐sugar eluates prepared from antibody‐coated tumor cells were found to contain two types of immunoglobulins—a large amount of IgG, and a very small amount of IgM. The cytotoxic activity was demonstrated to reside exclusively in the IgM fraction.

Immunogenicity of L 1210 murine leukaemia cells after treatment with neuraminidase.

THE privileged position of trophoblast and tumour cells may depend on a barrier which interferes with antigenic expression. As a working hypothesis it was suggested that cell surface sialomucins could act as a barrier to intimate contact between such privileged cells and lymphoid cells. Subsequent studies have indicated that histocompatibility antigens on mouse trophoblast can be detected after treatment with neuraminidase2. The increased immunogenicity of Landschutz ascites tumour cells after treatment by the same enzyme has also been reported from this laboratory3. This communication reports studies with another murine tumour. L 1210 (v) leukaemic cells were passaged every 5 days by 0.05 ml. of ascitic fluid in C57Bl/DBA2F1 mice. All passage animals which were not killed died within 8 days of injection, with haemorrhagic ascites and wasting.

Studies on a naturally occurring human antibody active against mouse Landschutz ascites tumor cells. I. Cytotoxicity assay system and quantitation in normal sera.

Abstract1. A quantitative cytolytic assay system was developed for the titration of the natural cytotoxin of human serum (NHS) which is active against Landschutz ascites tumor cells. The assay system consists of NHS52 or NHS as a source of antibody and human umbilical cord serum as a source of complement.2. Von Krogh plots of the cytotoxin and complement titration data gave 1/n slope values which were comparable to those obtained in the literature for acquired hemolytic and cytolytic immune systems. The values for the cytotoxin were compatible with those obtained with IgM antibodies.3. The level of this natural antibody in 101 individual sera was examined. Titers ranging from 10 to about 600 LD50 units/ml were found. On the average 93.4 units/ml were present.4. There was a relationship between blood group and antibody titer. The mean titers of groups O and A individuals were higher than those of groups B and AB individuals. This would indicate an antigenic cross‐reactivity between the B blood group antigen and antigen (s) on the ascites tumor cell.5. Guinea‐pig serum could replace human complement in the titration of the natural cytotoxic antibody but was much less effective than human complement.

Studies on a naturally occurring human antibody active against mouse Landschutz ascites tumor cells. II. Identification of the antibody as IgM and its partial purification.

Abstract1. The cytotoxic antibody in normal human serum, active against mouse tumor cells, was identified as a 19S macroglobulin by means of Sephadex gel filtration, DEAE‐cellulose chromatography and density‐gradient centrifugation procedures.2. A purified IgM fraction was isolated from normal human serum. The cytotoxic activity of this fraction, as tested against mouse tumor cells, was enriched 20–80 times over that of the unfractionated serum. The purified IgM showed mainly one precipitin line on immunoelectrophoretic analysis. In the ultracentrifuge the 19S peak comprised about 85% of the total protein.

The effects of ultraviolet and visible radiation on mouse ascites tumour cells.

Abstract— Effects of ultraviolet and visible radiation on the viability of Landschutz ascites tumour cells have been tested by growing control and treated tumour samples in adult mice. The tumour cells were irradiated as a dilute suspension in isotonic buffered salt solution, and were equilibrated at 0°C with oxygen or with nitrogen before irradiation.Tumour cell proliferation was measured by a variety of techniques. The preferred assay‐method was the growth of solid tumours in the axillae and groins of mice after sub‐cutaneous inoculation of varying dilutions of treated or control ascites tumour cells. The immune response of the mice to the injected cells was reduced by whole body irradiation with a 300r dose of x‐rays two days before inoculation. Results were calculated from parallel line assays using the reciprocal of the delay in appearance of the solid tumours up to 30 days post‐innoculation. This reciprocal (1/T) was linearly related to the logarithm of the number of cells inoculated.Photoreactivation has been demonstrated for this system, in which both U.V. and visible radiations were absorbed by the same cells. Light delivered alone in oxygen or in nitrogen was without effect on cell‐viability, but it increased cell‐survival after u.v.‐irradiation in nitrogen and decreased survival after u.v.‐irradiation in oxygen. Ultraviolet radiation alone was not significantly more lethal in oxygen than in nitrogen. A further observation in this work was an interaction between irradiated and control tumour cells injected into the same animal.It is suggested that the radiation used may affect the antigenic character of the tumour cells as well as their reproductive capadity.

THIOL GROUPS IN DEOXYRIBONUCLEIC ACID NUCLEOTIDYLTRANSFERASE.

1. The inhibitory effects of iodoacetate, iodoacetamide, p-hydroxymercuribenzoate and sarkomycin were studied in a partially purified preparation of deoxyribonucleic acid nucleotidyltransferase from Landschutz ascites-tumour cells. All of these agents inhibited the activity of the enzyme, and it was shown that the inhibition exerted by the last three compounds obeyed non-competitive kinetics. 2. Inclusion of glutathione or 2-mercaptoethanol in the enzyme assays did not prevent the inhibition by iodoacetate or iodoacetamide, but did prevent inhibition by p-hydroxymercuribenzoate. Inhibition by sarkomycin could be partially prevented by glutathione or 2-mercaptoethanol. 3. The enzyme fraction also catalysed incorporation in the presence of only one triphosphate (thymidine 5'-triphosphate), and the limited incorporation observed in these circumstances was more resistant to the inhibitory action of iodoacetamide and p-hydroxy-mercuribenzoate than was the standard nucleotidyltransferase reaction (four triphosphates present). Levels of inhibition imposed on the standard reaction were achieved in the limited incorporation reaction with 2.5-fold higher concentrations of the two inhibitors. 4. The addition of certain bivalent cations to the standard system resulted in severe inhibition of the reaction: Zn(2+) ions (10mum) gave 50% inhibition; ethylenediaminetetra-acetate (0.4mm) in the reaction mixture gave essentially complete protection against this inhibitory effect of Zn(2+) ions. 5. Deoxyribonucleic acid-nucleotidyltransferase fractions prepared in the presence of a thiol and ethylenediaminetetra-acetate could be stored without loss of activity for 2 months at 0 degrees or for 1 year at -70 degrees .

CHANGES IN THE PERMEABILITY OF LANDSCHUETZ ASCITES TUMOUR CELLS TO VITAL STAINS AFTER TREATMENT WITH TUMOUR-INHIBITORY OR MODIFIED SAMPLES OF GUM TRAGACANTH OR WITH GUM KARAYA.

Changes in the Permeability of Landschutz Ascites Tumour Cells to Vital Stains after Treatment with Tumour-Inhibitory or modified Samples of Gum Tragacanth or with Gum Karaya

Some studies on the enzymes of DNA biosynthesis

DURING the past few years there has been considerable progress towards elucidating the mechanisms of biosynthesis of deoxyribonucleic acid (DNA). Our group in Glasgow consisting of J. N. Davidson, H. M. Keir, M. G. Kellock, H. J. Grav and myself has been interested in the biosynthesis of DNA by enzyme systems derived from Ehrlich and Landschutz ascites tumour cells and other mammalian tissues. In particular we have been concerned with the enzymes responsible for the formation of thymidine 5’-triphosphate (TTP) from thymidine (TdR) and thymidine 5’-monophosphate (TMP) and in the polymerisation reaction leading to the synthesis of polydeoxyribonucleotides. The following aspects of this work will be discussed. (1) The conversion of TdR to TTP. (2) Some properties of the DNA nucleotidyltransferase (DNA polymerase) reaction. (3) An unusual nuclease from normal rat liver which interferes with the DNA nucleotidyltransferase reaction. (4) The intracellular location of DNA nucleotidyltransferase.

Feedback inhibition of thymidine kinase by thymidine triphosphate

THE search for rate-controlling enzyme systems in the overall synthesis of DNA has led a number of investigators to study the reactions in the sequence from Tdr to dTTP. Little duplication of effort has occurred despite the similarity in overall objectives. The work reported by Dr Smellie difiers from our work in terms of source of enzyme, reaction components, separation of products, method of quantitating the data, and problems emphasized [a]. Dr Smellie utilized extracts from the Landschutz ascites tumor cells while our work was done with extracts from the NlSl strain of cells grown in tissue culture in vigorously shaken suspensions in a modified Eagle medium. This strain was derived from Novikoff hepatoma cells and in addition to being the richest source of Tdr kinase and TMP kinase found, it is also notably lacking in side reactions that utilize Tdr. In the following scheme

A thermostable cytotoxic factor in normal human serum active against Landschutz ascities tumor cells.

SummaryA heat stable factor (SF) in normal human serum which is cytotoxic to Landschutz ascites tumor cells has been described. The cytotoxic action requires the presence of human or rabbit complement but guinea pig complement is ineffective. The substance is found in the beta-globulin fraction and has characteristics similar to C′4 of human complement. It is selectively absorbed on human and mouse tumor cells and human placenta but not by normal human liver, kidney or heart. SF inhibits the action of heterologous antibody on ascites and HeLa cells.We are indebted to Dr. A. Rimon, Marcus Memorial Blood Bank Institute, Jaffa, for the Cohn fractions, and to Dr. Esther Tenenbaum of this Department for a generous supply of HeLa cells and Chang cells.

Relation between ribonuclease activity and ribonucleic acid content.

THE penetration of ribonuclease into ascites tumour and bone marrow cells has been described elsewhere1. It was shown that the biochemical effects induced in different types of cells by the enzyme seems to depend on the original level of ribonuclease in these cells. Landschutz ascites tumour cells, which are very poor in ribonuclease as compared with bone marrow cells, are very much more sensitive to its action1,2. These observations, together with the fact that the bone marrow cells, although they are richer in ribonuclease, are poorer in ribonucleic acid, have led us to determine the normal level of ribonuclease in different organs of normal animals, and to attempt to find if there is a relationship between the content of ribonuclease and that of ribonucleic acid in normal and cancerous tissues.