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T Sugimura

Publications and source records attributed to T Sugimura.

At least 739 records · Page 41Linked to original sources
PubMed1983

Poly(ADP-ribose): structure, quantification, and biological significance.

We have been working on poly(ADP-Rib) since our discovery of it. This lecture will review recent findings on this polymer obtained in our laboratory. Poly (ADP-Rib) has long been thought to be a linear homopolymer attached to nuclear protein. The ribose-ribose bond of poly(ADP-Rib) was shown to be an alpha(1" leads to 2') ribosidic bond. There are two molecular forms of poly(ADP-Rib), namely low molecular weight (L) and high molecular weight (H) poly(ADR-Rib) molecules. The L and H fractions of poly(ADP-Rib) are separable by gel filtration, sucrose density gradient centrifugation and polyacrylamide gel electrophoresis. Physicochemically the L and H forms differ in their molecular size, solubility in high salt, rate of hydrolysis by venom phosphodiesterase and circular dichroism (CD) spectrum. However, the two forms have a similar ultraviolet (UV) absorption spectrum, both show a similar hyperchromicity on heating to 98 degrees C or hydrolysis with snake venom phosphodiesterase and give similar results on ordinary chain length determination. The great discrepancy in size observed by physicochemical methods and by the ordinary chain length method indicates the presence of a branching structure in poly(ADP-Rib). The branching structure was proved by demonstrating the presence of a unique compound, 2'[1"-ribosyl-2"(1"'-ribosyl)]adenosine-5',5",5"'-tris(phosphate) and by electron microscopy. The amount of poly(ADP-Rib) was determined by our new method, consisting of tritium labeling and high performance liquid chromatography. The merit of this method is that it can determine the recovery of poly(ADP-Rib) exactly and that its sensitivity is high. The amount of poly(ADP-Rib) changed dramatically when human promyelocytic leukemia cells were induced to differentiate by dimethyl sulfoxide or 12-O-tetradecanoylphorbol-13-acetate. The use of inhibitors of poly (ADP-Rib) polymerase in combination with bleomycin, a DNA damaging antitumor drug, potentiated the antitumor activity of bleomycin against Ehrlich ascites carcinoma cells in vivo.

Animals↗
PubMed1983

Comparative effects of aplysiatoxin, debromoaplysiatoxin, and teleocidin on receptor binding and phospholipid metabolism.

We have compared the activities of aplysiatoxin and debromoaplysiatoxin, two polyacetate marine algae toxins, with teleocidin, a tumor-promoting indole alkaloid from Streptomyces, with respect to inhibition of specific binding of epidermal growth factor, and phorbol-12,13-dibutyrate to their respective receptors and ability to stimulate the release of radioactivity from cells prelabeled with choline or arachidonic acid. Although these compounds have chemical structures that are quite different from the phorbol esters, both aplysiatoxin and teleocidin are essentially equipotent with the potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate in all four assays. The fact that aplysiatoxin and teleocidin inhibit phorbol-12,13-dibutyrate-receptor binding suggests that their biological activities are mediated by binding to the same receptors utilized by the phorbol esters. Debromoaplysiatoxin, a debrominated form of aplysiatoxin, is about 10-fold weaker than aplysiatoxin in inhibiting epidermal growth factor and phorbol-12,13-dibutyrate-receptor binding, but is equipotent with aplysiatoxin in stimulating the release of lipid metabolites from the prelabeled cells. The results are discussed in terms of possible heterogeneity of cellular receptors for this group of compounds.

Alkaloids↗
PubMed1983

Increase in the synthesis of a Mr 32,000 protein in BALB/c 3T3 cells treated with tumor-promoting indole alkaloids or polyacetates.

The synthesis of a unique protein with a molecular weight of 32,000 (p32) in BALB/c 3T3 cells has been shown previously to increase after treatment with potent tumor-promoting phorbol esters (Hiwasa et al., Proc. Natl. Acad. Sci. U. S. A., 79: 1800, 1982). In the present study, two new classes of tumor promoters which are structurally different from phorbol esters were investigated for their potencies to enhance p32 synthesis. Teleocidin, dihydroteleocidin B, and lyngbyatoxin A, which are indole alkaloid tumor promoters, enhanced p32 synthesis to the same extent that 12-O-tetradecanoylphorbol-13-acetate did. However, no increase was observed by treatment with the biologically inactive hydrolysate of teleocidin. Polyacetate tumor promoters such as aplysiatoxin and debromoaplysiatoxin also stimulated p32 synthesis, but their effective concentrations were higher than those of 12-O-tetradecanoylphorbol-13-acetate. When 3T3 cells were treated with a combination of two of the three tumor promoters, TPA, teleocidin, and aplysiatoxin, no synergistic effect of p32 synthesis was observed. This implies that these tumor promoters enhance the synthesis of p32 through the same mechanism.

Alkaloids↗
PubMed1983

Effects of tumor promoters on the frequency of metallothionein I gene amplification in cells exposed to cadmium.

Three potent tumor promoters of different classes, 12-O-tetradecanoylphorbol-13-acetate, dihydroteleocidin B, and aplysiatoxin, and two moderate tumor promoters, mezerein and debromoaplysiatoxin, enhanced the frequency of appearance of cadmium-resistant Chinese hamster lung cells when the cells were exposed to cytotoxic levels of CdCl2. With these compounds, the activity to induce cadmium-resistant cells correlated well with the potency of tumor-promoting activity. Cadmium resistance, which persisted after removal of the tumor promoters, was associated with the overproduction of metallothionein I messenger RNA. The amplified metallothionein I genes were shown by Southern blotting experiments. The relevance of the gene amplification caused by tumor promoters is discussed in relation to cancer development and progression.

Alkaloids↗
PubMed1983

Single-cell origin of bladder cancer induced by N-butyl-N-(4-hydroxybutyl) nitrosamine in mice with cellular mosaicism.

The single-cell origin of bladder cancer was established in mice with cellular mosaicism for phosphoglycerate kinase (PGK). Administration of N-butyl-N-(4-hydroxybutyl)nitrosamine in the drinking water resulted in development of large, solitary, infiltrating bladder carcinomas. On electrophoresis, PGK from all the cancer tissues examined gave only a single spot.

Animals↗
PubMed1983

Induction of diphtheria toxin-resistant cells by mutagen-carcinogens.

A mutation assay system with Chinese hamster lung (CHL) cells in culture has been established using diphtheria toxin resistance as a phenotypic selection marker. The results of series of studies on this mutation assay system are summarized and presented. Dose-dependent increase in the number of diphtheria toxin-resistant (DTr) cells was observed when the cells were exposed to a mutagen-carcinogen and then incubated in fresh medium for an expression period of 7 to 8 days. After exposure to ethyl methanesulfonate, the number of DTr cells was much higher than the number of thioguanine-or ouabain-resistant cells. ADP-ribosylation of elongation factor 2 (EF-2) catalyzed by diphtheria toxin was measured in cell-free extracts from the parent cells and 17 DTr cells, including 6 spontaneous DTr cells and 11 DTr cells induced by mutagens; the numbers of ADP-ribose molecules transfer to EF-2 in extracts of mutant cells were less than 1% of that in extract of the parent cells. Various mutagen-carcinogens, including heterocyclic amines isolated from pyrolysates of amino acids, proteins, and broiled fish, have been assayed with this mutation assay system in the presence or absence of a metabolic activation system and the results of these studies are also presented. In addition, a method to detect DTr cells in situ has been developed using autoradiographic method. The potential usefulness of this method for detection of DTr cells with no proliferative capacity to form colony and for analysis of cellular events occurring after exposure of the cells to mutagen-carcinogens is discussed.

Adenosine Diphosphate Ribose↗
PubMed1983

Monoclonal antibodies against poly(ADP-ribose) recognize different structures of poly(ADP-ribose).

The characteristics of two monoclonal antibodies to poly(ADP-Rib) and the various structures of poly(ADP-Rib) recognized by these monoclonal antibodies have been examined. One antibody, IgG monoclonal antibody 10H, reacted with most parts of poly (ADP-Rib) molecules, and its binding was only slightly inhibited by Ado(P)-Rib-P, a monomer unit of the polymer. On hydrolysis of poly(ADP-Rib) protected by the antibody hydrolytic products, such as Ado(P)-Rib-P and Ado(P)-Rib(P)-Rib-P, were almost the same as those from control poly(ADP-Rib). The other antibody, IgM monoclonal antibody 16B, recognized only some parts of poly(ADP-Rib) molecules of larger size, and its binding was not inhibited by Ado(P)-Rib-P. Branched portions were considerably concentrated in parts protected by this antibody. These two monoclonal antibodies are suggested to recognize different structures of poly(ADP-Rib): possibly IgG antibody 10H recognizes linear portions whereas IgM antibody 16B recognizes branched portions of the polymer. These monoclonal antibodies should be useful in studies on the structures, including unknown structures and the locations of these structures in poly(ADP-Rib).

Antibodies, Monoclonal↗
PubMed1983

Transforming activity of human melanoma DNA.

Cellular DNA transfection to mouse NIH3T3 cells revealed transforming activity of human malignant melanoma DNA. The corresponding human sequence was cloned from the transformed mouse cells. By hybridization to viral oncogenes, the transforming gene in human melanoma was identified as a homologue of viral Ha-ras gene.

Animals↗
PubMed1983

Distinct responses of 3T3-L1 cells to dihydroteleocidin B and the phorbol ester tumor promoters: relation to adipocyte differentiation, DNA synthesis and cell division.

We have recently shown that an indole alkaloid tumor promoter, dihydroteleocidin B (DHTB) is significantly different from the phorbol ester tumor promoters such as 12-O-tetradecanoylphorbol-13-acetate (TPA) in its potency and mode of inhibiting the adipocyte differentiation of 3T3-L1 cells (1). DHTB almost completely inhibited the differentiation induced by dexamethasone (DEX) and 1-methyl-3-isobutylxanthine (MIX) regardless of when the tumor promoter was added: before, during, or after the addition of inducers. Similar inhibition was observed by TPA with over 90% less efficiency and only when it was added during the inducer treatment. Both DHTB and TPA stimulated DNA synthesis to the same level during the initial 22 hr. The DNA synthesis of resting 3T3-L1 cells triggered by DHTB resulted in cell division, whereas TPA-stimulated DNA synthesis did not facilitate cell division. This observation is in sharp contrast to the previous findings that both DHTB and TPA stimulate a number of growth-arrested fibroblasts (2), including Swiss/3T3 from which 3T3-L1 cells were derived, to initiate DNA synthesis and undergo cell division (3). In order to further clarify this point we attempted to isolate cell variants which were no longer responsive to the mitogenic action of DHTB. Among 14 variant lines isolated, we found two stable variant lines, 1-2 and 2-3, whose DNA synthesis was not initiated by DHTB. DNA synthesis of another variant line, 3-4, was stimulated by DHTB but not followed by cell division. From these findings it is proposed that the modes of action of DHTB and TPA are similar in triggering DNA synthesis of G1-arrested 3T3-L1 cells, but DHTB can further act on 3T3-L1 cells at a point during or after S phase to stimulate events of mitosis.

Adipose Tissue↗
PubMed1983

Increase in frequency of appearance of cadmium-resistant cells induced by various tumor promoters; evidence for the induction of gene amplification.

When Chinese hamster lung (CHL) cells were cultured in medium containing 25 microM cadmium chloride, resistant cells appeared at a frequency of 0.04%. When one of three tumor promoters, 12-O-tetradecanoylphorbol-13-acetate (TPA), aplysiatoxin and dihydroteleocidin B, was added during selection with cadmium chloride, the frequency of appearance of resistant cells increased more than 50-fold. Two of the resistant clones obtained were characterized. Both clones produced much higher levels of metallothionein I mRNA than the parental CHL cells. Southern blot analysis showed that in these resistant cells, metallothionein I genes were amplified approximately 5-fold. Therefore, it seems that tumor promoters can enhance the frequency of gene amplification. One possible mechanism of the action of tumor promoters in oncogenesis is amplification of activated c-onc genes. Consistent with this idea, it has been reported that c-onc genes are amplified in various cancer cells. We also found that the c-Ha-ras and c-myc genes were amplified in a bladder cancer removed surgically and in a transplanted rat hepatocellular carcinoma, Morris hepatoma 7794A, respectively.

Animals↗
PubMed1983

L-Isoleucine and L-leucine are promoters of bladder cancer in rats.

We developed a short term assay for screening promoters of bladder cancer. This assay, in which maintenance of concanavalin A-agglutination of isolated rat bladder cells induced by subcarcinogenic treatment with bladder carcinogen is measured, suggested the possible promoting effects of L-isoleucine, L-leucine, D-tryptophan, and L-valin. Long term in vivo carcinogenesis experiments were carried out on L-isoleucine and L-leucine and it was shown that both were, in fact, promoters of bladder cancer in rats.

Animals↗
PubMed1983

Genetic control of susceptibility of rats to gastric carcinoma.

Genetic control of the induction of gastric tumors by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was studied in susceptible ACI rats, resistant Buffalo rats, and their F1 and F2 offspring. Both sexes of all strains, initially 7 to 9 weeks old, were given MNNG at a concentration of 83 micrograms/ml in their drinking water for 32 weeks and were sacrificed at experimental Week 72. The incidence of gastric adenocarcinoma in ACI rats was 80% in males and 47% in females; in Buffalo rats, the incidence was 18% in males and 0% in females. F1 hybrids showed the same resistance to MNNG as did Buffalo rats; the incidence of gastric adenocarcinoma was 17% in males and 8% in females. These results suggest that resistance to induction of gastric adenocarcinoma by MNNG is a dominant characteristic. The incidence of gastric adenocarcinoma in the F2 generation was 36% in males and 14% in females, which is close to the 3:1 ratio expected from the segregation of a single resistant gene. In ACI and Buffalo strains and their hybrids, males were more susceptible than females to induction of gastric carcinoma by MNNG. Intestinal tumors were observed mainly in the duodenum and jejunum in both strains and their hybrids, and the incidences were as follows: ACI: males, 67% and females 42%; Buffalo: males, 12% and females, 18%; F1: males, 18% and females, 15%; and F2: males, 15% and females, 19%. Thus, there seems to be a common genetic basis for both gastric and intestinal carcinogenesis by MNNG.

Animals↗
PubMed1983

Tumor promoter-dependent mouse leukemia cell line.

From a spontaneous AKR/Ms thymic leukemia symbiotically cultured with thymic epithelial reticular cells, a tumor promoter-dependent cell line A65T was established by passaging the cells in medium containing 12-O-tetradecanoylphorbol-13-acetate (10 ng/ml). The in vitro growth of A65T was strictly dependent on the presence of active tumor promoters. Their action was reversible, since withdrawal of 12-O-tetradecanoylphorbol-13-acetate resulted in rapid decrease in viability of the cells. Three classes of chemically unrelated compounds sharing tumor-promoting activity in mouse skin could support the in vitro growth of A65T: plant diterpene esters; indole alkaloids; and polyacetates. Their growth effect on A65T cells quantitatively correlated well with the tumor-promoting activity in mouse skin. However, other growth stimulators of epidermal cells such as cholera toxin and epidermal growth factor failed to support the growth of A65T. It is suggested that lymphokines such as interleukin-2 and interleukin-3 were not responsible for 12-O-tetradecanoylphorbol-13-acetate-stimulated growth of A65T because concanavalin A-stimulated spleen cell-conditioned medium containing both interleukin-2 and interleukin-3 activities as well as WEHI-3 cell culture supernatant containing potent interleukin-3 activity did not stimulate the proliferation of A65T cells. Furthermore, 12-O-tetradecanoylphorbol-13-acetate did not induce production of any significant amount of either activity in A65T cells. This cell line is useful for the screening of tumor promoters in environments although, so far, all the compounds capable of stimulating A65T growth have been limited to those competing with phorbol esters for the cellular receptor. Also, the cell line provides a potential model for analyzing growth requirements of developing mouse thymic leukemias.

Acetates↗