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Biomedical subjects

T Sugimura

Publications and source records attributed to T Sugimura.

At least 541 records · Page 30Linked to original sources
PubMed1988

Analysis of the stimulative effect of thapsigargin, a non-TPA-type tumour promoter, on arachidonic acid metabolism in rat peritoneal macrophages.

1. At concentrations above 10 ng ml-1, the tumour promoter thapsigargin stimulates the release of radioactivity from [3H]-arachidonic acid-labelled macrophages harvested from rat peritoneal cavity. 2. The release of radioactivity from prelabelled macrophages was augmented more than additively when the cells were incubated in the medium containing both thapsigargin (10 ng ml-1) and other tumour promoters (10 ng ml-1), such as 12-O-tetradecanoylphorbol-13-acetate (TPA), teleocidin and aplysiatoxin. 3. Thapsigargin required extracellular Ca2+ for the stimulation of arachidonic acid release, while TPA did not. 4. Cytoplasmic free calcium level was increased by thapsigargin treatment but not by TPA treatment. 5. An inhibitor of protein kinases, H-7 inhibited the effect of TPA dose-dependently, whereas H-7 did not inhibit that of thapsigargin. 6. These results suggest that thapsigargin stimulates arachidonic acid release by a mechanism different from that of TPA, viz by acting as a selective Ca2+ mobilizer, but not by activating protein kinase C as TPA does.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1988

Nucleotide sequences of cDNAs for human papillomavirus type 18 transcripts in HeLa cells.

HeLa cells expressed 3.4- and 1.6-kilobase (kb) transcripts of the integrated human papillomavirus (HPV) type 18 genome. Two types of cDNA clones representing each size of HPV type 18 transcript were isolated. Sequence analysis of these two types of cDNA clones revealed that the 3.4-kb transcript contained E6, E7, the 5' portion of E1, and human sequence and that the 1.6-kb transcript contained spliced and frameshifted E6 (E6*), E7, and human sequence. There was a common human sequence containing a poly(A) addition signal in the 3' end portions of both transcripts, indicating that they were transcribed from the HPV genome at the same integration site with different splicing. Furthermore, the 1.6-kb transcript contained both of the two viral TATA boxes upstream of E6, strongly indicating that a cellular promoter was used for its transcription.

Amino Acid Sequence↗
PubMed1988

Identification of a transforming activity suppressing sequence in the c-raf oncogene.

Our previous study revealed that the rat c-raf was activated by a rearrangement leading to replacement of the amino-terminal half of the product. Therefore, we suggested that some sequences present in the amino-terminal half might prevent c-raf from becoming an active oncogene. To examine this possibility, we constructed a series of deletion mutants of c-raf cDNA by the random linker insertion method. By transfection of NIH3T3 cells with these mutants, a region whose deletion resulted in activation of c-raf was identified. This region is located at amino acid residues 245 to 261, immediate upstream of the kinase domain of the c-raf product and is rich in serine and threonine residues. This region includes a sequence of six amino acids, RSTSTP, which is conserved in the products of normal raf gene families of various species. This sequence is the best candidate for suppressing transforming activity of c-raf.

3T3 Cells↗
PubMed1988

Heterogeneity of lung cancer cells with respect to the amplification and rearrangement of myc family oncogenes.

Seventy lung tumors from 53 patients were analysed for alterations of myc family oncogenes, c-myc, N-myc and L-myc, to evaluate when activation of these genes occurs during tumor development. The 53 cases were 17 small cell carcinomas (SCCs), 18 adenocarcinomas, 12 squamous cell carcinomas (SqCs), 4 large cell carcinomas and 2 adenosquamous carcinomas. Either N-myc or L-myc was amplified in 4 of the 17 (one N-myc and 3 L-myc) SCCs (24%), while c-myc was amplified in 3 of the 12 SqCs (25%). In one SCC, amplification of N-myc was found in the primary tumor, a pulmonary hilar lymph node metastasis and a pleural metastasis, but not in a liver metastasis or a para-aortic lymph node metastasis. In one SqC, c-myc was amplified in a pleural metastasis and a lymph node metastasis, but not in the primary tumor. In 2 cases of SCCs, amplification or rearrangement of c-myc was detected only in the cell lines, but not in the original tumors taken from the same individuals. These results indicate that tumor cells were heterogeneous for amplification and rearrangement of myc family oncogenes, and suggest that activation of these oncogenes in SCCs and SqCs occurs not at the time of malignant transformation but during tumor progression.

Chromosome Mapping↗
PubMed1988

Identification by a random linker insertion method of a region which suppresses the transforming activity of the raf oncogene.

Activation mechanism of raf oncogene was studied by applying in vitro mutagenesis to its cDNA. Previous studies suggested the presence of an activation suppressing sequence in the amino-terminal half of c-raf product. Loss of the sequence by genetic rearrangement was presumed to convert c-raf to possess transforming activity. To identify such sequence, we prepared cDNA mutants by random linker insertion. Synthetic oligonucleotide linker was inserted into the plasmid containing cDNA at a single and random site. Coupling two different mutants, in-frame deletion mutants were constructed systematically. Analysis of these deletion mutants revealed a region, the loss of which made c-raf activated.

Animals↗
PubMed1988

Altered expression of the retinoblastoma (RB) gene in small-cell carcinoma of the lung.

Nine lung small-cell carcinoma (SCC) cell lines and 9 lung non-SCC cell lines were examined for structural changes of the retinoblastoma (RB) gene as well as its expression using a complementary DNA probe. The RB protein product was investigated using an anti-RB antibody which we produced. Although homozygosity or hemizygosity of the RB gene was suggested in 8 of 9 SCCs and one of 2 large cell carcinomas (LCCs) by Southern blot analysis using an RB cDNA probe and polymorphic DNA markers for chromosome 13, no obvious structural changes of the RB gene were detected in these 18 cell lines. However, RB transcripts were either markedly reduced in quantity or abnormal in length in 3 of 9 SCCs. The specific 115 kD protein was not immunoprecipitated by the anti-RB antibody in all 9 SCCs with either normal or abnormal size RB mRNA. Three of 4 adenocarcinomas (AdCs), all 3 squamous cell carcinomas, and one of 2 LCCs expressed normal size RB mRNA, and the 115 kD protein was immunoprecipitated by the anti-RB antibody. The 115 kD protein was also absent in one of 2 LCCs with shortened RB mRNA and in one of 4 AdCs with low level of RB mRNA expression. These results strongly suggest that inactivation of the RB gene might be involved in the development of lung cancers, especially of SCCs.

Adenocarcinoma↗
PubMed1988

hst-1 transforming protein: expression in silkworm cells and characterization as a novel heparin-binding growth factor.

A protein encoded by an hst-1 transforming gene was expressed in silkworm-derived BmN cells and secreted into the culture medium using a recombinant baculovirus vector. The strong affinity for heparin of the secreted protein made it possible to purify the hst-1 protein to homogeneity in a two-step procedure. The purified hst-1 protein has a molecular weight of 18,000 and stimulates both DNA synthesis in NIH3T3 cells and human umbilical vein endothelial cell proliferation. In addition, morphological changes and anchorage-independent growth of NIH3T3 cells are induced by this product. These results show that the hst-1 transforming protein is a novel heparin-binding growth factor as predicted by nucleotide sequence analysis.

Animals↗
PubMed1988

Heterocyclic amine-DNA adducts analyzed by 32P-postlabeling method.

DNA adducts formed by 12 heterocyclic amines were analyzed by 32P-postlabeling method. Several DNA adducts were detected in rat liver by administration of each heterocyclic amine. Total adduct levels ranged from 0.5 for 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) to more than 250 for 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) per 10(7) nucleotides 24 hr after intragastric administration of these compounds. The N-hydroxy derivative of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) was reactive toward DNA in vitro to form adducts. Addition of acetic anhydride to N-OH-MeIQx greatly enhanced its reactivity to DNA. 32P-Postlabeling analysis revealed that the MeIQx-DNA adducts formed in vivo and in vitro were identical. Thus, MeIQx would be metabolized in vivo to N-hydroxy form and further esterified to produce more reactive species, such as N-acetoxy form, which modify DNA to form adducts.

Amines↗
PubMed1988

Molecular cloning and characterization of human ret-II oncogene.

A transformant having ret-II was obtained by transfection of NIH3T3 cells with DNA from a human sigmoid colon cancer. Comparison of the restriction map of ret-II with that of proto-ret revealed that the ret-II has rearrangements both 5' and 3' to the sequence coding for the kinase domain. However, only the upstream rearrangement was consistently observed in all transformants, suggesting that the upstream rearrangement resulted in the activation of proto-ret. The recombination point and replaced sequence of ret-II were different from those previously reported for ret (Takahashi et al., 1985). In addition, ret-II does not retain region coding for transmembrane of proto-ret. This rearrangement, however, was not detected in the original tumor DNA by Southern blot analysis.

Animals↗
PubMed1988

Local hyperthermia using a low powered Nd: YAG laser for pancreatic and gastric carcinoma.

The use of local interstitial hyperthermia using a low powered Nd: YAG laser (known as laserthermia) has been studied both in vivo and in vitro on two gastrointestinal carcinomas. Human pancreatic carcinoma subcutaneously transplanted into nude mice (n = 28) was treated using an interstitially placed frosted sapphire probe with a Nd: YAG laser at 3 watts maintaining a temperature increase of 42 degrees C - 43 degrees C for up to 20 minutes. Seven days after treatment, a marked necrosis of the pancreatic tumor was found resembling an ischemic infarction. The potential cytocidal effect of heat and low powered Nd: YAG laser energy was also tested in vitro using three different kinds of human gastric and pancreatic cancer cells. The cytocidal effect of heat was potentiated by the photolytic effect of the low powered Nd: YAG laser energy.

Adenocarcinoma↗
PubMed1988

Genetic alterations of the c-erbB-2 oncogene occur frequently in tubular adenocarcinoma of the stomach and are often accompanied by amplification of the v-erbA homologue.

We analyzed for alterations of the c-erbB-2 oncogene in 35 human stomach cancers and 8 cell lines derived from human stomach cancer. Amplification of c-erbB-2 was found in approximately 40% (5/13) of the tubular adenocarcinomas of the stomach examined, including 4 of 10 fresh tumors and one of 3 cell lines, but not in other histological types of stomach cancer examined (0/30), including 25 fresh tumors and 5 cell lines. This result strongly suggests that amplification of c-erbB-2 occurs frequently in tubular carcinomas in stomach cancer. Rearrangement of c-erbB-2 was also detected in one tubular adenocarcinoma. The rearranged fragment carried the 3' half, but not the 5' sequence, of the c-erbB-2 gene. Furthermore, one of the cellular homologues of v-erbA was amplified in 3 of 4 fresh tumors carrying the amplified c-erbB-2 gene. Both c-erbB-2 and the v-erbA homologue were expressed in all the stomach cancer cell lines tested.

Adenocarcinoma↗
PubMed1988

Retrospective study on amplification of N-myc and c-myc genes in pediatric solid tumors and its association with prognosis and tumor differentiation.

DNA was extracted from formalin-fixed and paraffin-embedded tissues of 85 patients with pediatric malignant solid tumors which had been resected at surgery or obtained at autopsy during a 24-year period. The tumors examined included 25 rhabdomyosarcomas, 12 Wilms' tumors, 10 hepatoblastomas and 37 neuroblastoma group tumors. Neuroblastoma group tumors were subclassified into 25 neuroblastomas and 12 ganglioneuroblastomas among which 6 composite ganglioneuroblastomas were included. Sample blocks were selected from both tumors and normal tissues in the majority of cases. We were able to reliably detect N- and c-myc gene amplification in tumor DNA by dot blot-hybridization. The N-myc gene showed approximately from 3- to 500-fold amplification in 19 of 33 cases of stage IV neuroblastoma group tumor. All of these 33 patients had been intensively treated with chemotherapy and/or radiotherapy. The c-myc was amplified 8-fold in 1 case of rhabdomyosarcoma, but neither N-myc nor c-myc was amplified in any cases of Wilms' tumor or hepatoblastoma. We retrospectively examined the association among N-myc gene amplification, prognosis, and histologic subtype in 33 patients with stage IV neuroblastoma group tumors. The survival of the patients with N-myc gene amplification was shorter than that of the patients without amplification of N-myc (p less than 0.05). There was no significant difference in prognosis between the 2 histologic subtypes; neuroblastoma and ganglioneuroblastoma, and the cases of tumors with amplified N-myc showed shorter survivals for each subtype (p less than 0.05). In every case of neuroblastoma group tumor, the copy number of the N-myc gene was the same among primary site and multiple metastatic tumors, even when the lesions showed differences in histologic subtype like neuroblastoma and ganglioneuroblastoma.

Child↗
PubMed1987

A 29 kDa GTP-binding protein expressed in mouse brain, lung, kidney, spleen and transformed NIH3T3 cells.

A novel 29 kDa GTP-binding protein has been detected in mouse brain, kidney, lung and spleen. The binding property is specific for guanine nucleotides, and the binding activity for GTP is retained after transfer of the 29 kDa protein to a nitrocellulose membrane. The 29 kDa protein is also expressed in NIH3T3 cells transformed by activated human c-Ha-ras, hst, ret and c-raf. The 29 kDa protein present constitutively in some mouse tissues is possibly involved in some cellular signal transduction relevant to the function of these tissues. In addition, its function may play a role in phenotype of transformed cells.

Animals↗
PubMed1987

Nucleotide sequence of a full-length cDNA for human fibroblast poly(ADP-ribose) polymerase.

The complete nucleotide sequence of human fibroblast poly(ADP-ribose) polymerase cDNA was determined. The cDNA contains an open reading frame for a 1014 amino acid polypeptide. In the DNA binding domain of poly(ADP-ribose) polymerase, there are predicted alpha-helix-turn-alpha-helix structures and two sequences each of about 100 amino acids that are similar to each other containing potential cysteine-zinc DNA binding structures. Within the 3' untranslated region, there is an AT-rich sequence containing ATTTA, a possible mRNA destabilizer.

Amino Acid Sequence↗
PubMed1987

Presence of different types of procollagen messenger RNAs in human hepatoma cell lines.

Human hepatoma cell lines were shown for the first time to contain various types of procollagen mRNAs. The amounts and types of procollagen mRNAs differed depending on the cell lines. Pro alpha 1 (III) and pro alpha 1 (IV) collagen mRNAs were present in PLC/PRF/5, a hepatocellular carcinoma cell line, whereas pro alpha 1 (I), pro alpha 2 (I), pro alpha 1 (IV) and pro alpha 2 (V) collagen genes contrast, HepG2 cells derived from hepatoblastoma contained little, if any, mRNAs for these types of procollagens we had examined.

Actins↗