PubMed Health⌕ Search

Biomedical subjects

T Sugimura

Publications and source records attributed to T Sugimura.

At least 487 records · Page 27Linked to original sources
PubMed1989

Formation of 8-hydroxydeoxyguanosine in DNA treated with fecapentaene-12 and -14.

Fecapentaene-12 and -14, direct-acting mutagens in human feces, were found to hydroxylate the C-8 position of guanine residues in DNA in vitro. Fecapentaene-12 or -14 was incubated with 0.5 mg of calf thymus DNA in 1 ml of reaction mixture at pH 7.4 for 2 h at 37 degrees C in the dark, and then 8-hydroxydeoxyguanosine (8-OH-dG) was analyzed. In these conditions 8-OH-dG was formed dose-dependently at levels of 1.1-4.6 residues/10(4) dG with concentrations of 0.5-3.0 mM of fecapentaene-12. Similar results were obtained with fecapentaene-14. The amount of 8-OH-dG in untreated DNA was 0.2-0.3 residue/10(4) dG.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1989

Detection of mRNA for the tax1/rex1 gene of human T-cell leukemia virus type I in fresh peripheral blood mononuclear cells of adult T-cell leukemia patients and viral carriers by using the polymerase chain reaction.

Expression of human T-cell leukemia virus type I (HTLV-I) is not detectable by immunofluorescence analysis or RNA blot analysis in most fresh peripheral blood mononuclear cells of patients with adult T-cell leukemia or of asymptomatic HTLV-I carriers. However, in this work, mRNA for the HTLV-I tax1/rex1 genes was detected in fresh peripheral blood mononuclear cells of adult T-cell leukemia patients and asymptomatic HTLV-I carriers by using reverse transcription followed by the polymerase chain reaction. By using fresh peripheral blood mononuclear cells, the expression of tax1/rex1 mRNA was detected in five of the six adult T-cell leukemia patients and four of the eight HTLV-I carriers examined. The amounts of tax1/rex1 mRNA detected corresponded to approximately 10(5) to 10(6) times less than that in the HTLV-I-infected MT-2 cell line. These results indicate that, in some individuals infected with HTLV-I, the provirus in circulating blood cells is transcribed in vivo. Thus the expression of viral antigens in circulating blood cells in vivo is suggested.

Adult↗
PubMed1989

Loss of the MYC gene amplified in human HL-60 cells after treatment with inhibitors of poly(ADP-ribose) polymerase or with dimethyl sulfoxide.

In HL-60 cells, a human promyelocytic leukemia cell line, the human c-myc gene, designated MYC, is amplified about 16-fold. On differentiation of the HL-60 cells into granulocytes induced by several inhibitors of poly(ADP-ribose) polymerase [NAD+ poly(adenosine diphosphate D-ribose)ADP-D-ribosyltransferase, EC 2.4.2.30] including benzamide, nicotinamide, coumarin, and 4-hydroxyquinazoline or dimethyl sulfoxide, some MYC loss was observed. In contrast, benzoic acid, a noninhibitory analogue of benzamide, did not induce either granulocytic differentiation or loss of MYC. Loss of MYC seems to be associated with granulocytic differentiation because the time course of its loss was similar to that of appearance of nitroblue tetrazolium-positive cells, mature granulocytes, and its loss was not observed on differentiation of HL-60 cells into macrophages induced by phorbol 12-myristate 13-acetate or teleocidin. The loss of MYC is not the reason for the down regulation of MYC expression observed within 1 hr after addition of inducers, since the loss of MYC was not detected by 1-day treatment with inducers.

Benzamides↗
PubMed1989

Flat reversion by okadaic acid of raf and ret-II transformants.

Okadaic acid is a non-phorbol 12-myristate 13-acetate (PMA)-type tumor promoter on mouse skin and known to be a potent inhibitor of serine/threonine protein phosphatases. Contrary to expectation from its tumor-promoting activity, okadaic acid was shown to have a potential to revert the phenotypes of cells transformed by raf and ret-II to that of normal cells. Two to 3 days after addition of 8 ng of okadaic acid per ml to the culture medium, raf and ret-II transformants changed to flat cells and gained contact inhibition. The amount of fibronectin, which was decreased in malignant transformed cells, was increased in the flat revertants. Moreover, okadaic acid caused a dose-dependent loss of ability to grow in soft agar. The morphology of the cells reverted to malignant phenotype within 1 week after removal of okadaic acid. The levels of mRNA and protein of activated c-raf in flat revertants were similar to those in parental transformed cells. The level of mRNA of ret-II was also not changed by flat reversion. No induction of flat reversion was observed with okadaic acid tetramethyl ether, an inactive compound, or a phorbol ester, PMA. As okadaic acid is a potent inhibitor of protein phosphatases 1 and 2A, the possibility that these phosphatases are involved in signal transduction from the raf and ret-II oncogenes is suggested.

Animals↗
PubMed1989

Induction of tumors in the Zymbal gland, oral cavity, colon, skin and mammary gland of F344 rats by a mutagenic compound, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline.

A mutagenic compound, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, which was first isolated from broiled sardines and was shown to be carcinogenic to mice, was also found to be carcinogenic to F344 rats. It induced tumors in various organs, such as the Zymbal gland, oral cavity, colon, skin and mammary gland of male and female rats when given at 0.03% in the diet. However, it was noteworthy that tumors were not observed in the liver. Most of the tumors in the Zymbal gland, oral cavity and skin were squamous cell carcinomas, and most of the mammary gland tumors were adenocarcinomas. The colon tumors were identified as adenomas or adenocarcinomas. In control rats no tumors developed in these organs during the 40-week experiment.

Animals↗
PubMed1989

DNA modification by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in rats.

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is the most abundant mutagenic heterocyclic amine by weight in cooked foods. This mutagen was found to produce DNA adducts in all ten tested organs of rats using the 32P-postlabeling method. The level of DNA adducts in the pancreas, kidney and liver increased dose-dependently and feeding time-dependently up to four weeks. When diet containing 0.05% PhIP was given to rats for four weeks, levels of PhIP-DNA adducts were relatively high in the lung, pancreas and heart, being around 20 per 10(7) nucleotides, and lowest in the liver, being 2.20 per 10(7) nucleotides. Thus, PhIP showed a unique feature in the formation of DNA adducts compared to other mutagenic and carcinogenic heterocyclic amines, which produce the highest level of DNA adducts in the liver.

Animals↗
PubMed1989

Presence of aberrant transcripts of ret proto-oncogene in a human papillary thyroid carcinoma cell line.

In a papillary thyroid carcinoma cell line, TPC-1, we found transcripts hybridizing to ret proto-oncogene (proto-ret) cDNA probes. The transcripts hybridized to the probes encoding the kinase domain but not to those of the transmembrane and extracellular domains of proto-ret. The sizes of the main transcripts in TPC-1 were aberrant, being 2.0, 2.5, 4.0 and 5.0 kb. In the neuroblastoma cell lines, the transcripts were 3.9, 4.5, 6.0 and 7.0 kb, which have been proved to be generated by alternative splicing and polyadenylation from the non-altered proto-ret oncogene. All of the four transcripts in TPC-1 are about 2 kb smaller than the corresponding ones in the neuroblastoma. From the length of the transcripts, it is suspected that the transcripts in TPC-1 are a rearranged form of proto-ret. This is the first report describing the aberrant transcripts of proto-ret in a human tumor.

Blotting, Northern↗
PubMed1989

Leukocyte tissue-type plasminogen activator activity in dialysis patients.

Plasma fibrinopeptide B beta 15-42 was significantly high in undialyzed and hemodialyzed chronic renal failure (CRF) patients, indicating that the fibrinolytic system as well as the coagulation system is stimulated. There are two kinds of plasminogen activators (PA) for the fibrinolytic system: urokinase (UK) and tissue-type PA (t-PA). PA activity of peripheral leukocytes from healthy volunteers, continuous ambulatory peritoneal dialysis (CAPD) patients and hemodialysis (HD) patients was measured and compared. Peripheral leukocyte PA in the euglobulin fraction was purified using zinc-chelate-Sepharose 6B column and Concanavalin A-Sepharose column chromatography. The different PA activity was quantitatively identified by electrophoretic enzymography and was confirmed using antibody against UK and t-PA. PA activity of peripheral leukocytes was significantly higher in HD patients on the cupro-ammonium processing membrane dialyzer than in CAPD patients and healthy volunteers. All PA activity in the three groups was UK, and t-PA was not detected. This suggested that the inflammatory response was continuously induced in HD patients, resulting in the induction of PA activity of the leukocytes and plasma, and that different mechanisms were involved for the synthesis or secretion of UK and t-PA.

Adult↗
PubMed1989

Biological significance of the hst-1 gene.

hst-1, or HSTF1 in human gene nomenclature, was originally identified as a transforming gene in DNA samples from human stomach cancer by NIH3T3 transfection assay. Many reports have followed to show the presence of a transforming hst-1 gene in various types of cancerous and noncancerous tissues, suggesting that the hst-1 gene is the most common non-ras transforming gene. We cloned the hst-1 genomic fragments from DNAs of a normal individual and a patient with leukemia and also from NIH3T3 cells themselves. All of these clones transformed NIH3T3 cells upon transfection. Sequence analysis of the cDNA and genomic hst-1 led us to conclude that the normal hst-1 protein transforms NIH3T3 cells when its expression is deregulated. The hst-1 protein has 40-50% homology to basic and acidic fibroblast growth factors (FGFs) and to the int-2 protein. The purified hst-1 protein synthesized in a baculovirus system was a potent heparin-binding growth factor for a variety of cells, including human endothelial cells. The hst-1 protein, when it was added to the culture medium, induced morphological transformation of NIH3T3 cells and anchorage-independent growth of NRK cells. The hst-1 gene is located 35 kbp downstream of one of its homologous genes, int-2, on human chromosome 11 at band q13.3. As in the case with the int-2 gene, the hst-1 transcripts were not detected in adult mice but found in mouse embryos. A relatively large amount of the hst-1 message was present in a mouse teratocarcinoma cell line, F9, while the int-2 mRNA was barely detected. Upon induction of differentiation in vitro, the hst-1 transcription was depressed to almost nil, and the int-2 message increased dramatically. The hst-1 and int-2 genes were coamplified in a variety of cancer cells, most notably in more than 50% of esophageal cancers.

Animals↗
PubMed1989

Antigenic relationship among strains of ibaraki virus and epizootic haemorrhagic disease virus studied with monoclonal antibodies.

Twelve monoclonal antibodies against ibaraki virus (IbV) were established and preliminarily characterised by indirect immunoperoxidase (IIP), haemagglutination inhibition (HI) and neutralisation (NT) tests. Five antibodies reacted in the IIP test with all IbV and epizootic haemorrhagic disease virus (EHDV) strains tested, and five antibodies reacted with IbV and Alberta strain (serotype 2) but not with New Jersey strain (serotype 1) of EHDV. Two of 12 antibodies showed both HI and NT activities. Viral proteins with molecular weights of about 24,000 daltons (24KD) and 78KD were determined by two monoclonal antibodies in Western blot analysis. One of two antibodies with the ability of both HI and NT recognised a viral protein with a molecular weight of about 78KD.

Animals↗
PubMed1989

Role of protein phosphatases in malignant transformation.

Many oncogene products are protein kinases and signals are transduced via phosphorylation of proteins. Similarly, protein-dephosphorylation may play a critical role in malignant cell transformation. We have cloned two catalytic subunits of ser/thr protein phosphatase (PP) type 2A, PP2A alpha, and PP2A beta, from a rat liver cDNA library. Both cDNAs encode peptides of 309 amino acids with a difference of only 8 amino acids between the two. All primary hepatocellular hyperplastic nodules or carcinomas, which were induced by a food carcinogen, 2-amino-3-methylimidazo[4,5-f]quinoline, showed up-regulation of expression of the mRNAs of both PP2A alpha and PP2A beta. NIH3T3 cell transformants obtained by introducing activated c-raf, ret-II or Ki-ras oncogenes also showed high levels of PP2A alpha transcripts. Okadaic acid, a non-TPA type tumor promoter, was found to be a potent inhibitor of PP1 and PP2A. Its IC50 for PP1 was much higher than that for PP2A with phosphorylase a as a substrate. When raf and ret-II transformants were cultured with okadaic acid at 8 ng/ml for 2 days, both transformants became flattened and showed strict contact inhibitions. This flat cell morphology was stable for at least one month in the presence of okadaic acid, but in its absence, the cells reverted to their original transformed shape within 7-10 days. Colony formation by raf and ret-II transformants in soft agar was inhibited dose-dependently by okadaic acid; very few colonies grew in the presence of the acid at 8 ng/ml. Okadaic acid had less effect on a transformant of the Ha-ras gene, causing only 50% inhibition of colony formation at 8 ng/ml. The role of protein phosphatases in cellular transformation by certain oncogenes is suggested.

Animals↗
PubMed1989

Multiple genetic alterations in small-cell lung carcinoma.

By restriction fragment length polymorphism (RFLP) analysis, it was found that loss of heterozygosity (LOH) at three different chromosomal loci, 3p, 13q, and 17p, occurs simultaneously in nearly 100% of small-cell lung carcinomas (SCLC). This was observed even in stage I tumors and an untreated tumor, and it occurred prior to NMYC amplification. The common region of LOH on chromosome 3p was 3p14-24.1, and this region was also frequently lost in carcinoma of the uterine cervix (100% at D3S2 on 3p14-21) as well as renal cell carcinoma (56% at ERBA beta on 3p22-24.1), suggesting the presence of tumor suppressor gene(s) for these cancers in this region. On chromosome 13, LOH was observed commonly in the region between 13q12 and 13q22, including the RB locus on 13q14, and normal RB protein was not detected in any of 9 SCLC cell lines by immunoprecipitation analysis. The common region of LOH on chromosome 17 was 17p13 and is the same as that in colon carcinoma and osteogenic sarcoma. Since LOH is supposed to unmask the recessive mutation of tumor suppressor gene in the remaining allele, these results may imply that at least six genetic alterations are necessary to convert a normal cell into a fully malignant cancer cell in SCLC. RFLP analysis was performed on several other types of human cancers, including carcinoma of the uterine cervix, neuroblastoma, hepatocellular carcinoma, pheochromocytoma, and stomach cancer to determine the chromosomal loci of putative tumor suppressor genes in each tumor. Chromosomal loci showing frequent LOH were different among these tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Small Cell↗
PubMed1989

Hereditary hepatitis in LEC rats: accumulation of abnormally high ploid nuclei.

The LEC (Long-Evans with a cinnamon-like coat color) rat is a new mutant strain with hereditary hepatitis. The rate of DNA synthesis, the relative amounts of binucleated cells, and the polyploidizations of LEC hepatocytes have been analyzed. Markedly high polyploidy, such as 32n and 64n, were detected after manifestation of hepatitis; however, no aneuploidy was detected. Bi-, tri- and tetranucleated cells whose nuclei occasionally differed in size were observed after the manifestation of hepatitis. In addition to small hepatocytes and oval cells in the periportal area of the hepatic lobule, enlarged cells with huge nuclei were also labeled with BrdU, indicating that in LEC rats suffering from hepatitis abnormal mitosis may be relevant to high polyploidization and multinucleation. Polypeptide analysis using 2D-PAGE detected the apparent lack of expression of two polypeptides, p29.5 and p30, in LEC liver cells; however, linkage analysis indicated no correlation between these peptide defects and the manifestation of hepatitis.

Aging↗
PubMed1989

Human ret proto-oncogene mapped to chromosome 10q11.2.

Using cosmid clones derived from human ret protooncogene as probes, we determined its chromosome localization by fluorescence in situ hybridization. Two overlapping clones, cret-1 and -2, which were cloned using the most 5' part of human ret proto-oncogene cDNA, hybridized to chromosome 10q11.2. Sixty-three and 52% of the grains obtained by cret-1 and -2, respectively, were localized to the same site. No other specific hybridization site was observed. From these data, we assigned the site of ret proto-oncogene to chromosome 10q11.2, where the possible locus responsible for multiple endocrine neoplasia type 2A (MEN2A) was mapped by linkage analysis using interstitial retinol binding protein cDNA and D10S5. These findings suggest that ret proto-oncogene might be a suitable probe for approaching the MEN2A locus.

Chromosome Mapping↗