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Biomedical subjects

F Itoh

Publications and source records attributed to F Itoh.

At least 163 records · Page 9Linked to original sources
PubMed1992

Protein-tyrosine phosphatase expression in pre-B cell NALM-6.

Protein-tyrosine phosphatase (PTP)-related complementary DNAs from NALM-6 (pre-B cell line) were amplified by reverse transcriptase polymerase chain reaction using primers corresponding to the conserved catalytic domains of PTPs. Thirty-three polymerase chain reaction products, identified as PTP related complementary DNAs, were classified to RPTP-alpha, PTP1B, and 4 novel PTPs, which were designated as BPTP-1-4. Their expressions in NALM-6 and other cell lines were confirmed by Northern blot analysis. BPTP-1 and -2 exhibited extensive homology with the first and the second catalytic domains, respectively, of leukocyte common antigen related molecule (LAR) and human PTP delta. The transcriptional sizes of BPTP-1 and BPTP-2 are the same (7.2 kilobases) as that of LAR. The expression of BPTP-1 was abundant in lymphoid cell lines TALL-1 and NALM-6 but small in colon cell line BM314, which is in sharp contrast to the expression of LAR. These data suggest that the expression levels of BPTP-1 and LAR are altered in a cell specific manner, probably making them cell type associated PTPs.

Amino Acid Sequence↗
PubMed1992

cDNA cloning of new protein tyrosine phosphatases in the human colon.

Oligonucleotide probes corresponding to three invariant amino acid sequence motifs within the protein tyrosine phosphatase (PTPase) catalytic domain were synthesized and employed in the polymerase chain reaction (PCR). PCR products amplified from human colonic tissues were analyzed. Among 41 cDNA clones sequenced, two putative novel PTPases designated as CL-6 and CL-2B were isolated. cDNA cloning of CL-6 was performed, and three overlapped cDNA clones encoding part of the coding region, which was 2.1 kb long, were obtained. Expression of mRNAs of these clones was then investigated by Northern blot analysis or reverse transcriptase-PCR, suggesting that CL-6 mRNA may be expressed in a cell-type-specific manner, whereas the expression of CL-2B mRNA could be ubiquitous.

Base Sequence↗
PubMed1992

Chemical modification of fumagillin. I. 6-O-acyl, 6-O-sulfonyl, 6-O-alkyl, and 6-O-(N-substituted-carbamoyl)fumagillols.

The hydroxy group of fumagillol (3), a degradation product of fumagillin (1), was acylated, sulfonylated, alkylated or carbamoylated, and the anti-angiogenic activity of the resulting products was examined. These compounds inhibited the angiogenesis induced by basic fibroblast growth factor in the rat corneal micropocket assay and the growth of vascular endothelial cells in vitro. Among them, compound 2 (AGM-1470) was found to show the most potent inhibitory effect on the growth of vascular endothelial cells and was selected from this series as a candidate for further development.

Animals↗
PubMed1992

Identification and analysis of the ret proto-oncogene promoter region in neuroblastoma cell lines and medullary thyroid carcinomas from MEN2A patients.

The human ret proto-oncogene (proto-ret), encoding a receptor tyrosine kinase, is highly expressed in neuroblastomas, medullary thyroid carcinomas (MTCs) and pheochromocytomas, which are all tumors of cells originating from the neural crest. In studies on the transcription mechanism of proto-ret, we identified the transcription start site and the promoter region by chloramphenicol acetyl transferase (CAT) assay. A sequence upstream from the transcription start site (-167 to +98 bp) showed definite promoter activity in both proto-ret mRNA-positive neuroblastoma NB39-nu cells and proto-ret mRNA-negative HeLa cells. The promoter sequence had a high GC content and contained four tandemly repeated GC boxes without a TATA box. Putative binding sequences for SP-1, AP-2 and epidermal growth factor receptor-specific transcription factor (ETF) and also the transcription-suppressing factor, GC factor (GCF), were found in the repeated GC box region. Southern blot analysis of DNAs of neuroblastoma cell lines and primary MTCs showed that the high proto-ret expression in these tumors is not caused by gross genetic changes in the promoter region, suggesting the possible involvement of a region(s) other than the sequence from -167 to +98 bp or a minor genetic change(s) in the promoter region.

Amino Acid Sequence↗
PubMed1992

Expression of two types of kit ligand mRNAs in human tumor cells.

The primary structure of human kit ligand (KL) growth factor mRNA was analyzed by polymerase chain reaction (PCR) and nucleotide sequencing. Two bands from the total RNAs of a variety of human tumor cell lines were amplified by RT-PCR. Nucleotide sequences of these cloned cDNAs revealed that an 84-nucleotide stretch, corresponding to a spacer chain which contains the site for proteolytic release of the cytokine domain, was missing in the shorter clone, resulting in a transmembrane-bound form of KL. The relative intensity of the two bands in human bone marrow and tumor cells was then determined. In the bone marrow cells, THP1 and HuH7, the band for the membrane-bound type of KL was relatively more intense, whereas the reverse was the case in Daudi, K562 and HT1080 cells, suggesting that there are variations in the expression level of these two human KL mRNAs.

Amino Acid Sequence↗
PubMed1991

Potent anti-angiogenic action of AGM-1470: comparison to the fumagillin parent.

The anti-angiogenic activity of AGM-1470, a new synthetic analog of fumagillin isolated from Aspergillus fumigatus, was extensively examined both in vitro and in vivo using four different types of assay and compared to that of the fumagillin parent. Locally administered AGM-1470 inhibited the angiogenesis in the chick embryo chorioallantoic membrane assay and the rat corneal assay. In the rat sponge implantation assay, systemically administered AGM-1470 inhibited angiogenesis induced by basic fibroblast growth factor. Furthermore, in the rat blood vessel organ culture assay, AGM-1470 (1-1,000 ng/ml) was found to selectively inhibit the capillary-like tube formation of endothelial cells with a minimal effect on the non-endothelial cell growth. AGM-1470 showed more potent anti-angiogenic activity and less toxicity than the fumagillin parent. Therefore, AGM-1470 is much better than the fumagillin parent as anti-angiogenic compound.

Animals↗
PubMed1991

Co-expression of X-hapten-like antigen and antigen YH206 on mucin molecules.

The asialocarbohydrate antigen YH206 is expressed on adenocarcinoma-associated mucin molecules which lack epitopes of CA19-9 and DU-PAN-2. To further characterize this molecule, the monoclonal antibody BM2 against the affinity-purified antigen YH206 was established. It was demonstrated by an inhibition test that antigen BM2 was an X-hapten-like structure, one of the representative oncodevelopmental antigens. Although the sensitivity of antigen BM2 in sera of stomach and pancreas cancer patients did not appear to be superior to that of antigen YH206, both antigens were complementary to each other resulting in the improvement of sensitivity. Interestingly, double-determinant enzyme immunoassays showed that antigen BM2 and YH206, both having a cryptic nature for neuraminidase, were co-expressed on the same mucin molecule in sera of patients with stomach cancer or liver cirrhosis. These data suggest that mucin molecules in serum might be classified into several groups based on the distribution of tumor-associated epitopes.

Adenocarcinoma↗
PubMed1991

Tight linkage of the ret proto-oncogene with the multiple endocrine neoplasia type 2A locus.

The ret proto-oncogene has been mapped to 10q11.2 near the MEN2A locus by in situ hybridization. We carried out a linkage study of Japanese multiple endocrine neoplasia type 2A (MEN2A) families using a cosmid clone containing the ret proto-oncogene as probe. Two polymorphic alleles (A1 and A2) could be detected by digesting DNA with EcoRI: allele A1 was detected as a 10 kb fragment and A2 as 5.4 and 4.6 kb fragments. Of 11 Japanese MEN2A families analysed, four were informative, and the maximum lod score was 4.23 at a recombination fraction of 0.00. This result suggests the ret proto-oncogene to be close to the MEN2A gene and therefore possibly to be a useful DNA marker for cloning the latter.

Chromosome Mapping↗
PubMed1991

Expression of the ret proto-oncogene in human neuroblastoma cell lines and its increase during neuronal differentiation induced by retinoic acid.

Previously we observed specific expression of the ret proto-oncogene (proto-ret) in human neuroblastoma cell lines. A neuronal subline and non-neuronal sublines were isolated from the SK-N-SH cell line, which is composed of a heterogeneous cell population. Expression of proto-ret was detected in the neuronal subline, named SH-4305, but not in three non-neuronal sublines. Expression of proto-ret in the SH-4305 cells increased markedly after treatment with retinoic acid for 1 day, with concomitant morphological change, namely neurite outgrowth, and induction of neurofilament mRNA expression. Induction of proto-ret expression seemed to be correlated with neurite outgrowth and increase of neurofilament mRNA expression. These data suggest that the proto-ret product plays a role in neuronal differentiation.

Blotting, Northern↗
PubMed1990

Immunological agglutination kinetics of latex particles with physically adsorbed antigens.

The influence of the properties of antigens and particles on the immunological agglutination kinetics of the antigen-coated latex particles was studied. Horse cytochrome c, hen egg-white lysozyme (HEL), bovine serum albumin (BSA), and Aspergillus sp. glucose oxidase were physically adsorbed onto the surfactant free latices of styrene-methacrylic acid (MAA) copolymer (P (S/MAA)) and polystyrene (PS). The initial rates of the immunological agglutination of these protein-coated particles initiated by the addition of antibodies were quantified by the absorbance change at a wavelength of 680 nm. The initial agglutination rates of the particles covered with smaller antigens were lower. This effect of the molecular size of antigens was larger in P(S/MAA), because small antigens are probably buried in the hydrous polymethacrylic acid layer on the surface of particles. Thus, both the molecular size of antigens and the surface properties of particles affect the sensitivity of the immunological agglutination. On the other hand, the dependence of the initial rate of the immunological agglutination on the ionic strength and pH was similar irrespective of antigen-particle systems. The initial agglutination rates were largest at an ionic strength of approximately 0.05 at pH 7.0 and decreased with increasing pH. This dependence of the sensitivity on the pH and ionic strength is attributed to the electrostatic interactions of particle-particle and antibody-particle.

Adsorption↗
PubMed1990

Isolation of fatty acid amide as an angiogenic principle from bovine mesentery.

Erucamide (13-docosenamide) was found to be the major bovine mesentery angiogenic lipid as assessed by chorioallantoic membrane (CAM) assay. Two micrograms of this lipid caused angiogenesis in the assay. Angiogenic activity of this naturally occurring lipid was also found by rat corneal micropocket and mouse dorsal air-sac assays. Specificity of the chemical structure which elicited activity was low, however. The mechanism of angiogenic activity is unknown and this lipid does not promote proliferation of endothelial cells or induce inflammatory effects.

Angiogenesis Inducing Agents↗
PubMed1990

Heparin enhances thrombin-stimulated prostaglandin I2 production by cultured endothelial cells.

Endothelial cells from human umbilical vein were incubated in vitro with thrombin in the absence or presence of unfractionated heparin (UFH), low molecular weight heparin (LMWH) or dermatan sulfate (DS) to clarify the effect of these glycosaminoglycans on thrombin-stimulated prostaglandin I2 (PGI2) production. Although DS did not affect the thrombin stimulation, UFH and LMWH each enhanced it about 1.5-fold. Pretreatment of cells with either UFH or LMWH also enhanced the thrombin stimulation. In addition, UFH and LMWH each enhanced PGI2 production stimulated by calcium ionophore A23187, but did not affect that stimulated by arachidonic acid. From these results, it was suggested that UFH and LMWH might cause a physical change of cell membrane, which would caused an easier liberation of arachidonic acid by phospholipases.

Arachidonic Acid↗
PubMed1990

Expression of ret proto-oncogene in human neuroblastomas.

We examined the expression of ret proto-oncogene (proto-ret) in surgically resected human neuroblastomas. Slot blot RNA hybridization revealed that all 29 neuroblastomas examined expressed the proto-ret, the relative intensity of the hybridization ranging from 1 to 48. No correlation was found between the level of expression of proto-ret and the clinical stage. The level of expression was also not correlated with N-myc amplification, the patient's age or the histological type of the tumor. Based on the previous finding that proto-ret expression is very rarely detected in tumor cell lines other than those of neuroblastoma, proto-ret expression was suggested to be a characteristic of neuroblastomas, and possibly to be involved in the genesis of neuroblastomas.

Actins↗
PubMed1990

Characterization of ret proto-oncogene mRNAs encoding two isoforms of the protein product in a human neuroblastoma cell line.

The ret proto-oncogene expresses four major mRNA species of different lengths in human malignant cell lines and rat tissues. We isolated ret proto-oncogene cDNA clones from a cDNA library of a human neuroblastoma line, Nagai, which over-expressed these mRNAs. Four cDNA clones differing from each other in their 3' portions were analysed. The sequence of the region common to the cDNA clones is essentially identical to a reported cDNA sequence derived from THP-1 monocytic leukemia cells, that encodes a protein with characteristic features of receptor-type tyrosine kinase. From the 3' heterogeneity, two isoforms of the ret proto-oncogene product of 1072 and 1114 residues that differed from each other in their 9 and 51 C-terminal amino acids are predicted. Comparison of the structures of cDNA clones with that of the genomic clone showed that the 3' heterogeneity is produced by alternative polyadenylation and splicing of mRNA. Northern blot analysis using various fragments of cDNA indicated that the 4.5 kb, 3.9 kb and possibly 7.0 kb transcripts may encode a protein of 1072 residues, while the 6.0 kb transcript and a (minor) 4.6 kb transcript may encode a protein of 1114 residues.

Amino Acid Sequence↗