Biomedical subjects

M Seiki

Publications and source records attributed to M Seiki.

At least 163 records · Page 9Linked to original sources

PubMed1993

[Expression of matrix metalloproteinases in tumor cells].

Tumor cells have to degrade extracellular matrix components to invade surrounding tissue and to form metastatic colonies at distant organs. Matrix metalloproteinases are the enzymes that can degrade various types of native collagens and glycoproteins. In this study, we demonstrated the roles of matrix metalloproteinases in metastatic colony formation in chick embryo by transfecting TIMP-1 gene into a metastatic gastric cancer cell line, KKLS. The mechanism regulating expression of one of the type IV collagenases, MMP-9, was also studied using the promoter region of the gene.

Extracellular Matrix↗

PubMed1992

Interaction of HTLV-1 Tax1 with p67SRF causes the aberrant induction of cellular immediate early genes through CArG boxes.

Tax1 of human T-cell leukemia virus type 1 (HTLV-1) is a transcriptional activator for viral gene expression and is also a transforming protein through inducing the expression of several cellular genes under the control of mitogenic signals. We identified the CArG boxes as a Tax1-responsive cis-acting element for the cellular immediate early genes c-fos, egr-1, and egr-2. Using a chimeric protein consisting of the CArG-binding factor p67SRF and the heterologous DNA-binding domain of a yeast transcription factor GAL4, we demonstrated that Tax1 activates the transcriptional activity of p67SRF through the GAL4-binding site. The carboxy-terminal half of p67SRF, which lacks domains for DNA-binding, dimerization, and ternary complex formation with p62TCF, was sufficient for the activation by Tax1. Tax1 produced in Escherichia coli bound p67SRF in vitro. The complex formation in vivo was also indicated by the finding that the acidic activation domain of VP16, by fusion to p67SRF, can complement the transcriptional activation function of a mutant Tax1 in trans. Thus, Tax1 activates CArG-mediated transcription without mitogenic signals through interaction with a CArG-binding factor, p67SRF. This must be one of the primary steps by which Tax1 causes aberration in growth control of the infected cells.

Base Sequence↗

PubMed1992

Experimental metastasis of oncogene-transformed NIH 3T3 cells in chick embryo.

By means of a highly sensitive and quantitative assay for specific detection of metastasized tumor cells in chick embryonic organs using the polymerase chain reaction (PCR), we have examined the experimental metastatic ability of individual clones of NIH 3T3 cells, transformed with oncogenes: v-Ki-ras, v-Ha-ras, v-src, v-fos, and v-abl. Such a transformed clone had different metastatic abilities in different embryonic organs. Among them, two clones of NIH 3T3 cells transformed with ras-oncogenes (v-Ki-ras or v-Ha-ras) metastasized to liver and lungs of chick embryo, and grew there more rapidly than the other clones. The parental NIH 3T3 cells were detected as slight bands of PCR products after iv injection, indicating some cells were trapped in chick embryonic organs, but did not grow. These findings indicate that the transformed cells are able to invade the organ tissues and grow in embryonic chick organs, but non-metastatic cells such as the untransformed-NIH 3T3 cells are not able to grow in the secondary sites. These experiments clearly demonstrate the usefulness of this assay system to study genes involved in malignant transformation.

3T3 Cells↗

PubMed1992

Epstein-Barr virus BZLF1 transactivator is a negative regulator of Jun.

The Epstein-Barr virus BZLF1 protein that can induce the lytic cycle in latently infected cells is a transcription factor partially homologous to Fos and binds not only the canonical TPA (tetradecanoyl phorbol acetate)-responsive element (TRE) site but also sequences deviating from the TRE consensus sequence. Thus, expression of cellular genes regulated by AP-1, including the autoregulated AP-1 family, should be affected by BZLF1. However, induction of only Fos by BZLF1 was observed in a gel mobility shift assay using an oligonucleotide probe containing the TRE sequence and the antibody against Fos protein. The c-jun promoter, which contains a binding site for Jun and BZLF1, was stimulated by Jun but not by BZLF1. Furthermore, BZLF1 inhibited stimulation of the c-jun promoter by Jun. Jun together with Fos effectively activated the collagenase promoter that contains a single TRE site. However, not only was BZLF1 unable to stimulate the collagenase promoter, but it also inhibited activation by Jun and Fos. On the other hand, BZLF1 stimulated constructs containing multimeric binding sites. These results and those of previous studies of Epstein-Barr virus promoters regulated by BZLF1 indicate that BZLF1 requires adjacent multiple DNA-binding sites for cooperative interaction to function as a transactivator and to repress the activation by Jun of promoters containing a single TRE site. This suggests that BZLF1 evolved to confer distinct regulatory patterns upon viral target genes and cellular AP-1-responsive genes.

Base Sequence↗

PubMed1992

[Effect of Z-103 on wound healing by dermal incision in guinea pigs].

We investigated the effects of Z-103, ZnSO4, L-carnosine and solcoseryl on wound healing by dermal incision in guinea pigs. The tensile strength, hydroxyproline contents and the value of angiogenesis (carmine contents) at the wounded site of dorsal skin were used as indices of wound healing. Z-103, given daily s.c., increased the tensile strength and hydroxyproline contents on day 4 after operation in a dose-dependent manner; in particular, the effect of 10 mg/kg of Z-103 was nearly equal to that of solcoseryl at 0.5 ml/animal. Moreover, Z-103 10 mg/kg increased the value of angiogenesis on day 3 after the operation. On the other hand, ZnSO4 and L-carnosine, components of Z-103, also similarly increased the tensile strength and hydroxyproline contents. These results suggest that Z-103 possessed an accelerative action on wound healing, and these effects may be due to the activity of its components, ZnSO4 and L-carnosine.

Animals↗

PubMed1992

[The gastric mucosal adhesiveness of Z-103 in rats with chronic ulcer].

The gastric mucosal adhesiveness of Z-103 in rats with acetic acid ulcer was studied macroscopically, histologically, and biochemically. From macroscopical observations, when Z-103 was orally administered to an acetic acid ulcer model, there was adhesion of Zn to the normal mucosa as well as the ulcerous site under both the fasting condition and after feeding. It was also proven that the strength and duration of adhesiveness were increased dose-dependently under fasting conditions. In addition, histological localization of Zn was noted from the covering epithelial cell layer to the gastric lamina propria mucosae in the normal tissue and in the most superficial ulcerous layer and the granulous layer of the ulcerous site. Measurement of the gastric tissue Zn content after oral administration of 100 mg/kg of Zn showed that the Zn content was significantly increased for 6 hr at the normal site and for 24 hr at the ulcerous site. On the other hand, although ZnSO4 and ZnSO4+carnosine combination macroscopically produced generally the same level of adhesiveness as Z-103, when the gastric tissue Zn content for Z-103 and ZnSO4 were compared, the Zn content of ZnSO4 was lower than that for Z-103 at both the normal and ulcerous site. In summary, Z-103 shows a long-term adhesive and permeable action on the gastric mucosa in acetic acid ulcer rats, and it has a comparable high affinity at the ulcerous site.

Acetates↗

PubMed1992

[Studies on the healing promoting action of Z-103 in chronic gastric ulcer models of rats].

We studied the healing promoting action of Z-103 on the chronic gastric ulcer induced by acetic acid (AAU) or Fe-ascorbic acid (FAU) in rats. The area of the gastric ulcers, hydroxyproline (Hyp) and DNA contents in the ulcer region were measured as an index of ulcer healing. The area of gastric ulcers was the largest on day 4 and thereafter gradually decreased, but the ulcers still remained at the 14th day. Hyp contents in the ulcer region decreased until the 7th day in both models, and then this level increased. Significant decrease in DNA contents in the ulcer region was observed on the 7th day only in FAU. In AAU and FAU, administration of Z-103 (3 mg/kg/day x 2, p.o.) resulted in a significant decrease in the area of gastric ulcers on the 14th day and a significant increase in Hyp contents in the ulcer region on the 7th day as compared with the control group. Z-103 increased the DNA contents in the ulcer region on the 4th day in AAU and on the 7th day in FAU. These results suggest that tissue destruction surrounding the ulcer region in AAU and FAU models might occur until the 4th or 7th day after operation, and that the acceleration of ulcer healing by Z-103 on these models may be facilitated by the wound healing action of this drug.

Animals↗

PubMed1992

Effects of a new histamine H2-receptor antagonist, Z-300, on gastric secretion and gastro-duodenal lesions in rats: comparison with roxatidine.

We examined the effects of a new compound, N-[3-[3-(piperidinomethyl)phenoxy]-propyl]-2-(2-hydroxyethyl-1- thio)acetamido.2-(4-hydroxy benzoyl)benzoate (Z-300), on the histamine H2-receptor, gastric secretion in rats and dogs, and acute gastro-duodenal lesions or chronic gastric ulcers in rats. Roxatidine acetate hydrochloride (roxatidine), a known histamine H2-receptor antagonist, was used as a reference compound. The pA2 values for Z-300 and roxatidine for the isolated guinea pig atrium were 6.8 and 7.0, respectively. These agents at less than 10(-5) M did not affect the contraction of guinea pig ileum in response to carbachol. Z-300, administered either orally or parenterally, significantly inhibited the basal and histamine-stimulated gastric acid secretion in rats. Gastric acid secretion stimulated by histamine, pentagastrin or carbachol in Heidenhain pouch dogs was also significantly inhibited by the compound. The effect persisted for greater than 7 hr in the case of histamine-stimulation. Oral Z-300 significantly protected the gastric mucosa from water-immersion stress-, indomethacin-, aspirin- and HCl.ethanol-induced lesions and protected the duodenal mucosa against mepirizole- and cysteamine-induced ulcers. These effects on gastric secretion and lesion formation were, as a whole, stronger than those observed with roxatidine. Z-300, but not roxatidine, significantly accelerated the spontaneous healing of acetic acid ulcers induced in rats and prevented the delay in ulcer healing caused by indomethacin. The mechanism of action of Z-300 on acute lesions and chronic ulcers appears to be mostly related to its potent antisecretory and mucosal-protective activities.

Acetamides↗

PubMed1992

Expression of genes encoding type IV collagen-degrading metalloproteinases and tissue inhibitors of metalloproteinases in various human tumor cells.

Uncontrolled expression of matrix metalloproteinases 2, 3 and 9 (MMP-2, -3 and -9) is believed to be a critical part of the invasive potential of tumor cells because of their ability to degrade type IV collagen, a major structural component of basement membranes. Availability of proteolytic activity in the vicinity of the cell surface is further affected by a local balance between the enzymes and their inhibitors produced by the cell. To determine how frequently deregulated expression of the MMPs and tissue inhibitors of metalloproteinases (TIMPs) is associated with tumor cells, 26 human tumor cell lines were examined by Northern blotting. Transcripts for MMP-2 and MMP-9 were more frequently expressed in mesenchymal tumor cells (9/9 for MMP-2 and 6/9 for MMP-9) than in epithelial tumor cells (4/17 for MMP-2 and 2/17 for MMP-9). Although expression of MMP-2 mRNA was clearly cell type-specific, MMP-9 mRNA expression in mesenchymal cells correlated well with the reported tumorigenicity of the cells. Enhanced expression of MMP-9 mRNA was also associated with the tumorigenic transformation of cells by an activated c-H-ras gene in human embryonic fibroblasts. Only 3 of the 26 tumor cells expressed MMP-3 mRNA, and 2 of the 3 were epithelial tumor cells which coordinately expressed MMP-9 and TIMP-1 mRNAs. TIMP-1 mRNA was almost undetectable in 50% of the tumor cells, but TIMP-2 mRNA was expressed in the majority of the cells. These findings provide comprehensive information about mRNA expression of the MMPs and TIMPs in tumor cells, the deregulation of which is thought to be an integral part of the invasive potential of tumor cells.

Cell Transformation, Neoplastic↗

PubMed1991

Comparison of autocrine mechanisms promoting motility in two metastatic cell lines: human melanoma and ras-transfected NIH3T3 cells.

Tumor-cell migration plays an essential role in invasion into surrounding tissues and the formation of metastatic colonies in distant organs. Metastatic human A2058 melanoma and ras-transfected NIH3T3 cells produce autocrine motility factors (AMFs) which stimulate their own motility, and the A2058 cell AMF (AMF/A2058) has been purified. In this study, we partially purified the AMF produced by N-ras-transfected NIH3T3 cells (AMF/NIH3T3) and compared it with AMF/A2058. The two AMFs differed in their gel filtration patterns and heat stability, although both elicited migration of N-ras-transfected NIH3T3 cells. The receptor for AMF/A2058 in A2058 cells is linked to a pertussis-toxin-sensitive GTP-binding protein. Pre-treatment of N-ras-transfected NIH3T3 cells with pertussis toxin also specifically blocked the promotion of motility by AMF/A2058, but did not affect the activity of AMF/NIH3T3. Stimulation of N-ras-transfected NIH3T3 cells by both AMFs elicited an additive response. Thus, the autocrine mechanisms of these two metastatic tumor cell lines are different with regard to the AMF molecules, receptors, and signal transduction pathways.

Animals↗

PubMed1991

Antiulcer agents. II. Synthesis and gastric acid antisecretory activity of N-[3-(3-(piperidinomethyl)phenoxy)propyl]-4-(1-methyl-1H- tetrazol-5-ylthio)butanamide and related compounds.

N-[3-(3-(Piperidinomethyl)phenoxy)propyl]butanamides having a 1-methyl-1H-tetrazol-5-ylthio moiety as a pharmacophore and related compounds were prepared and tested for their antisecretory activity against histamine-induced gastric acid secretion in conscious rats with gastric fistulas. Most of the compounds showed antisecretory activity. Among them, N-[3-(3-(piperidinomethyl)phenoxy)propyl]-4-(1-methyl-1 H-tetrazol-5-ylthio)butanamide (5f) was found to posses the most potent activity, and a possibility of isosteric replacement of the methoxycarbonyl group with 1-methyl-1H-tetrazol-5-yl group was indicated. The structure-activity relationships are also discussed.

Animals↗

PubMed1991

A novel fibrinolytic enzyme extracted from the earthworm, Lumbricus rubellus.

A strong fibrinolytic enzyme was readily obtained in saline extracts of the earthworm, Lumbricus rubellus. It hydrolyzed not only plasminogen-rich fibrin plates, but also plasminogen-free fibrin plates. The average fibrinolytic activity was about 100 CU (plasmin units) or 250 IU (urokinase units)/g wet weight. The molecular weight and isoelectric point were about 20,000 and 3.4, respectively. The enzyme was heat-stable and displayed a very broad optimal pH range. DFP and SBTI strongly inhibited the enzyme, but the anti-plasmin agent, t-AMCHA, exerted little effect under the same conditions. Purification of the enzyme was performed and three partially purified fractions were obtained. These three fractions were further subdivided. The first fraction (F-I) was divided into three fractions (F-I-0, F-I-1, and F-I-2), which exhibited similar biochemical characteristics. The second fraction (F-II) could not be subdivided. The third fraction (F-III) was divided into two fractions (F-III-1 and F-III-2). Based on results for their enzymatic activities against various substrates, the fraction I enzymes are thought to represent a chymotrypsin-like enzyme and the fraction III enzymes to represent a trypsin-like enzyme. The fraction II enzyme appears to be neither a trypsin- or chymotrypsin-like enzyme nor an elastase. The amino acid compositions of the six enzymes were estimated. Compared with other serine enzymes, these enzymes contained very abundant asparagine or aspartic acid, and there was very little proline or lysine. From the above data, these enzymes are regarded as novel fibrinolytic enzymes, and we name them collectively as Lumbrokinase from the generic name of the earthworm.

Amino Acids↗

PubMed1991

HTLV-1 Tax has distinct but overlapping domains for transcriptional activation and for enhancer specificity.

Tax1 of human T-cell leukemia virus type 1 (HTLV-1) activates viral transcription dependent upon three 21-bp enhancer elements in the long terminal repeat. Difficulties in detecting any association of Tax1 with the viral enhancer have hampered elucidation of the molecular mechanisms of Tax1-mediated transcriptional activation. By constructing a fusion protein with the heterologous DNA-binding domain of yeast GAL4, Tax1 was shown to be a potent transcriptional activator dependent on the presence of GAL4-binding sites. Deletions of the Tax1 portion of the fusion protein revealed that almost the entire region of Tax1 (amino acids 2-337) is required for activation, and the activity correlated well with that of the viral enhancer. The GAL/Tax1 mutant lacking 41 residues of the C-terminus of Tax1, GAL/Tax1(2-312), was inactive for the viral enhancer, but activity was recovered by adding the heterologous activation domain of herpes simplex virus VP16. These results indicate that Tax1 has two distinct but overlapping functional domains for transcriptional activation and for enhancer specificity. Thus, Tax1 is thought to be a transcription factor acting in the enhancer complex rather than as a catalytic or allosteric modifier of pre-existing cellular transcription factors.

Amino Acid Sequence↗

PubMed1991

HTLV-1 Tax induces expression of various immediate early serum responsive genes.

Human T-cell leukemia virus type 1 (HTLV-1) is an etiological agent of adult T-cell leukemia (ATL). We showed here by mobility-shift assay that T-cell lines transformed with the virus contained high levels of AP-1 activities. Consistent with this result, these cell lines expressed increased levels of mRNAs encoding the AP-1 proteins, c-Fos, Fra-1, c-Jun, JunB, and JunD. Previously, transcription of the c-fos gene has been reported to be transactivated by the viral transcription factor, Tax1. By using the human T-cell line (JPX-9), in which expression of the Tax1 is inducible, we showed that expression of mRNAs for Fra-1, c-Jun, and JunD was also transactivated by Tax1. Moreover, Tax1 activated expression of two other transcription factors having zinc finger motifs, Egr-1 and Egr-2, in the same cells. The Tax1-inducible transcription factors identified here are encoded by the members of immediate early genes under the control of growth signals. Thus, Tax1 was suggested to replace growth signals, at least in part, by this mechanism.

Base Sequence↗

PubMed1990

Induction and stimulation of 92-kDa gelatinase/type IV collagenase production in osteosarcoma and fibrosarcoma cell lines by tumor necrosis factor alpha.

Production of a 92-kDa gelatinase/type IV collagenase and tissue inhibitor of metalloproteinases (TIMP) was investigated with human sarcoma cell lines. Among the cytokines and growth factors examined, only human recombinant tumor necrosis factor alpha (TNF alpha) induced and stimulated the proteinase with concomitant increase in TIMP expression, but matrix metalloproteinase 2 (72-kDa gelatinase/type IV collagenase) expression was unchanged. These data suggest that gene expression of the two metalloproteinases is regulated in a different fashion and TNF alpha may be important to allow cancer cells to be more invasive and metastatic.

Cell Line↗

PubMed1990

Retrovirus from human T-cell leukemia virus type I-associated myelopathy is the same strain as a prototype human T-cell leukemia virus type I.

A retrovirus was isolated from a T-cell line that was established from lymphocytes in the cerebrospinal fluid of a patient with human T-cell leukemia virus type I-associated myelopathy (HAM), and its genome was sequenced. The nucleotide sequence of the 3' half of the total genome was identical in 99.5% of the nucleotides to that of the prototype human T-cell leukemia virus type I that was derived from a patient with adult T-cell leukemia. These results indicate that the same retrovirus human T-cell leukemia virus type I is associated with both a neurological disease, HAM, and a lymphoproliferative disease, adult T-cell leukemia.

Amino Acid Sequence↗

PubMed1990

Effects of zinc L-carnosine on gastric mucosal and cell damage caused by ethanol in rats. Correlation with endogenous prostaglandin E2.

The effects of zinc L-carnosine on ethanol-induced damage and the correlation of these effects with endogenous prostaglandin E2 were evaluated in rat gastric mucosa in vivo and in vitro. When given either intragastrically or intraperitoneally, zinc L-carnosine (10 or 30 mg/kg) prevented gross visible damage to gastric mucosa caused by ethanol without affecting the mucosal prostaglandin E2 level. This protective effect of zinc L-carnosine was not inhibited by indomethacin. Histological assessment showed that zinc L-carnosine inhibited deep mucosal necrosis, as did 16,16-dimethyl prostaglandin E2. Zinc L-carnosine (10(-6) or 10(-5) M) inhibited the damage caused by ethanol to gastric cells isolated from rat gastric mucosa in vitro; this effect was not inhibited by indomethacin. The results suggested that zinc L-carnosine protects the gastric mucosa and enhances cellular resistance to ethanol without the mediation of endogenous prostaglandins.

16,16-Dimethylprostaglandin E2↗

PubMed1990

The U5 sequence is a cis-acting repressive element for genomic RNA expression of human T cell leukemia virus type I.

The long terminal repeat (LTR) of HTLV-1 consists of U3-R-U5 and contains elements which regulate the viral gene expression. In addition to these elements, we found that the U5 sequence contained a repressive element in the gene expression. Sequential deletions of the LTR substantially increased CAT expression of a LTR-CAT construct. The repressive effect was also observed at RNA level on unspliced RNA, but not on spliced RNA. These differential effects suggest that the U5 element is a cis-acting RNA element, since splicing within the R segment removed the U5 element. In the context of HTLV-1 gene expression, the U5 element would repress expression of unspliced genomic RNA of HTLV-1, but not subgenomic RNA.

Cell Line↗