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Biomedical subjects

K Toyoshima

Publications and source records attributed to K Toyoshima.

At least 181 records · Page 10Linked to original sources
PubMed1990

Immunohistochemical study on overexpression of c-erbB-2 protein in human breast cancer: its correlation with gene amplification and long-term survival of patients.

Using a polyclonal antibody monospecific to the c-erbB-2 oncogene product, an immunohistochemical study on the expression of c-erbB-2 protein was performed in formalin-fixed, paraffin-embedded tissue sections from 176 primary breast carcinomas in which amplification of the c-erbB-2 gene had been detected in 28 cases. Expression of the c-erbB-2 protein was detected in 44 cases (25%), being strongly positive in 27 (15%) and weakly positive in 17 (10%). All cases with amplification of c-erbB-2 showed positive staining of its protein. There were only four cases in which c-erbB-2 was strongly expressed without amplification of the gene. In the group showing strongly positive staining, both overall and disease-free survival were significantly poorer than in the remainder of the cases. Using Cox's regression model analysis, overexpression of c-erbB-2 protein was demonstrated to be an effective prognostic factor independent of nodal status or tumor size.

Amino Acid Sequence↗
PubMed1990

Purification and characterization of alkaline phosphatase of Bacteroides gingivalis 381.

Cell-associated alkaline phosphatase (ALPase) of Bacteroides gingivalis 381 was found in the outer part of the periplasmic space by using an ultracytochemical procedure. Cell-associated ALPase was solubilized by extraction with 1% Triton X-100, and the solubilized enzyme was purified 904-fold with 5.6% recovery by using affinity column chromatography for mammalian intestinal-form ALPase. The purified enzyme gave a single protein band that corresponded to the enzyme activity band on polyacrylamide gel electrophoresis preparations. A single protein band at a molecular weight of 61,000 was observed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis preparations. The molecular weight of the native enzyme was estimated to be 130,000 by gel filtration with TSK-gel G3000SW. These findings indicate that B. gingivalis ALPase is a homodimer. The optimal pH of the enzyme was between 9.1 and 9.3 in the absence of divalent metal ions and was between 10.1 and 10.3 in the presence of manganese or zinc ions. The apparent km for p-nitrophenylphosphate was 0.037 +/- 0.003 mM (mean +/- standard deviation) at pH 9.2 in the absence of divalent metal ions and 0.22 +/- 0.02 mM at pH 10.2 in the presence of 1 mM manganese ions. Under both of the conditions described above, the purified enzyme was able to hydrolyze casein and O-phosphoserine, suggesting that B. gingivalis ALPase can act as a phosphoprotein phosphatase. ALPase that immunologically cross-reacted with the purified enzyme was found in the extracellular soluble fraction. This means that ALPase is released from the periplasmic space into the culture supernatant as a soluble form.

Alkaline Phosphatase↗
PubMed1990

Specific expression of human c-fgr in natural immunity effector cells.

The c-fgr gene product was shown by immune complex protein kinase assay with specific antibodies to be a 58-kilodalton protein (p58c-fgr) with tyrosine-specific autophosphorylating activity. On examination of peripheral blood cells by immunoblotting with anti-c-fgr antibodies, p58c-fgr was found only in the fractions of monocytes, granulocytes, and natural killer cells. On the other hand, histochemical studies of hybridization demonstrated accumulation of c-fgr transcripts on most monocytes and large lymphocytes. In hematopoietic cell lines, p58c-fgr was detected in differentiated granulocytic cells as well as in differentiated monocytic cells of HL-60-cell origin. These data suggest a specific role for p58c-fgr in natural immunity effector cells.

Animals↗
PubMed1990

Transformation of chicken embryo fibroblast cells by avian retroviruses containing the human Fyn gene and its mutated genes.

The transforming activity of the human fyn protein, p59fyn, which is a kinase of the src family, was investigated by testing the effect of recombinant avian retrovirus (Fyn virus) expressing p59fyn on chickens or cultured chicken embryo fibroblast (CEF) cells. The Fyn virus did not induce transformed foci. After several passages of the virus stock on CEF cells, however, a few foci were detected in the presence of dimethyl sulfoxide. Chickens inoculated with Fyn virus at the stage of 12-day-old embryos developed fibrosarcomas 3 to 6 weeks after hatching. The viruses obtained from these foci and from one of the tumor tissues showed high transforming activity in the presence of dimethyl sulfoxide, suggesting that these viruses carry spontaneous mutations of the fyn gene. Four fyn genes from CEF DNAs infected with transforming viruses were molecularly cloned, and their products were confirmed to possess transforming activity. DNA sequence analysis of the fyn genes showed that two of the four mutants have Thr instead of Ile at position 338 in the kinase domain. The other two mutants carry deletions of 78 and 108 base pairs, respectively, which result in complete loss of region C of SH2. The overall level of proteins containing phosphotyrosine was significantly higher in transformed cells than in normal CEF cells. Our data indicate that when expressed at high levels in a retrovirus, normal p59fyn cannot cause cellular transformation, but that mutant p59fyn with either a single amino acid substitution in the kinase domain or a deletion including region C produces a transforming protein, perhaps due to enhanced tyrosine kinase activity. This is the first observation that deletion of region C can unmask the potential transforming activity of a src family kinase.

Amino Acid Sequence↗
PubMed1990

[Proto-oncogene C-erbB-2 and human cancer].

The C-erbB-2 gene was first found in human genomic DNA as a sequence which had homology in nucleotide sequence to the V-erbB by molecular hybridization under relaxed conditions. The product of this gene is a receptor type protein-tyrosine kinase which has a structure highly related to that of epidermal growth factor receptor (EGF-r: C-erbB-1). The proto-neu gene is a rat counterpart of the C-erb B-2 gene. The C-erbB-2 gene is also called as the HER-2 gene. The C-erbB-2 gene acquires the ability to transform NIH 3 T 3 cells by, 1) mutation which alters valine 659 in transmembrane region to glutamic acid as was found in neu gene activation, 2) deletion of c-terminal regulatory domain or 3) gene-amplification or overexpression. C-erbB-2 expresses in human embryos on mucous membranes and glands, but only faintly in adult tissues. High expression or gene amplification in human tumor appeared to be an indication for high risk of metastasis or high degree of malignancy.

Adenocarcinoma↗
PubMed1990

Variable mutations of the RB gene in small-cell lung carcinoma.

Loss of heterozygosity for chromosome 13q including the RB locus is a common genetic alteration in small-cell lung carcinoma (SCLC) as well as in retinoblastoma. We examined the RB cDNA sequences of exon 13 to 18 and exon 19 to 23 in 9 SCLC cell lines to detect mutations which cause inactivation of the remaining allele of the RB gene. Internal deletions of RB cDNA were observed in 3 of the 9 SCLC cell lines. In the Lu-24 cell line, a 114 base pairs (bp) deletion corresponding to exon 22 was due to abnormal splicing, which probably resulted from a two-base mutation within genomic exon 22, and aberrant 105 kilodaltons RB protein was detected by immunoprecipitation analysis. A base pair deletion within exon 20 in the Lu-135 cell line and a 1 bp deletion within exon 23 in the Lu-141 cell line were due to the deletions of the corresponding genomic DNA, and each deletion resulted in formation of a premature termination codon. These results indicate that both alleles of the RB genes are inactivated in SCLC by several different mechanisms, including small deletion, mutation and chromosomal loss.

Alleles↗
PubMed1990

Monoclonal antibodies to the amino-terminal sequence of the c-yes gene product as specific probes of its expression.

An amino terminal sequence of 64 amino acid residues specific to human c-yes was expressed in E. coli as a fused molecule with a bacterial phosphate binding protein. The fused protein was used as both immunogen for mice and antigen to obtain monoclonal antibodies against the c-yes protein. Monoclonal antibodies (MAbs) from two monoclonal hybridomas (1B7: IgG2a, 3H9: IgG1) recognized human p62c-yes in blotting analyses. In addition, MAb3H9 reacted with murine p62c-yes. The p62c-yes immunoprecipitated with Mab1B7 exhibited protein tyrosine kinase and autophosphorylation activities in vitro. Immunohistochemical analysis with MAb1B7 showed that the p62c-yes expression in the kidney was confined to the proximal tubules.

Adult↗
PubMed1990

Marked alteration in phosphorylation of the RB protein during differentiation of human promyelocytic HL60 cells.

The phosphorylation state of the RB protein was found to change markedly during cell differentiation: most of the RB protein was in a highly phosphorylated 115 kD form in human promyelocytic HL60, erythroleukemic K562 and monocytic U937 cells, but during tumor promoter-induced differentiation, the amount of this form decreased and the amount of an under-phosphorylated 110 kD form of the RB protein increased. Induction of differentiation of HL60 cells by dimethylsulfoxide also induced a similar alteration of the RB protein. However, no alteration in the ratio of the two forms was observed in cell lines such as epidermoid carcinoma A431 and adenocarcinoma MKN-7 that were not induced to differentiate by tumor promoter treatment. The highly phosphorylated form and under-phosphorylated form exhibited different affinity for DNA-cellulose and SV40 large T antigen.

Antigens, Polyomavirus Transforming↗
PubMed1989

Activation of the serum response element and 12-O-tetradecanoylphorbol-13-acetate response element by the activated c-raf-1 protein in a manner independent of protein kinase C.

Transfection of the cDNA encoding the activated c-raf-1 protein or addition of 12-O-tetradecanoylphorbol-13-acetate (TPA) or dibutyryl cAMP to NIH/3T3 cells activated the c-fos gene enhancer linked to the chloramphenicol acetyltransferase or luciferase reporter gene. Prolonged treatment of NIH/3T3 cells with phorbol 12,13-dibutyrate caused down-regulation of protein kinase C. In these cells, addition of TPA did not stimulate the c-fos gene enhancer any more, but transfection of the c-raf-1 cDNA or addition of dibutyryl cAMP still stimulated the c-fos gene enhancer to the same extent as those induced in the control cells. Transfection of the c-raf-1 cDNA or addition of TPA to NIH/3T3 cells stimulated the serum response element and TPA response element but not the cAMP response element. In contrast, addition of dibutyryl cAMP to NIH/3T3 cells stimulated the cAMP response element but not the serum response element or TPA response element. These results indicate that the activated c-raf-1 protein stimulates the serum response element and TPA response element in a manner independent of protein kinase C and cAMP-dependent protein kinase. Since the c-fos gene enhancer has been shown to contain the serum response element and cAMP response element, it is most likely that the c-raf-1 protein is involved in the regulation of c-fos gene expression through the serum response element.

Animals↗
PubMed1989

Correlation between long-term survival in breast cancer patients and amplification of two putative oncogene-coamplification units: hst-1/int-2 and c-erbB-2/ear-1.

The incidence and association with 10-year survival of amplification in five protooncogenes or transforming genes were retrospectively examined using DNAs extracted from formalin-fixed, paraffin-embedded blocks of tissues obtained from 176 consecutive patients surgically treated for primary breast carcinoma. The incidences of greater than threefold amplification of hst-1, int-2, c-erbB-2, ear-1 (one of c-erbA), and c-myc were 12, 13, 16, 10, and 4.0%, respectively. hst-1 and int-2 were almost always coamplified (21/22), while c-erbB-2 and ear-1 were frequently coamplified (18/28) with almost the same copy number. The hst-1 and int-2 pair and the c-erbB-2 and ear-1 pair, localized on chromosomes 11q13 and 17q21-22, respectively, in normal cells, were inferred to be constituents of different amplification units. Amplification of hst-1 and/or int-2 was detected preferentially in the younger age group, and was correlated with poorer prognosis in cases carrying four or more copies of the genes. Amplification of c-erbB-2 and/or ear-1 was strongly correlated with poor prognosis in all 176 patients, especially those with lymph node metastasis. Amplification of c-myc was also correlated with poor prognosis. Cox's life-table regression analysis showed that amplification of c-erbB-2 had a prognostic value, which was independent of other known prognostic factors such as lymph node status and tumor size.

Breast Neoplasms↗
PubMed1989

Two erbA homologs encoding proteins with different T3 binding capacities are transcribed from opposite DNA strands of the same genetic locus.

Two erbA homologs, termed ear-1 and ear-7, are present in the human genome on chromosome 17. The two genes reside in the same genetic locus with overlapping exons and are transcribed from opposite DNA strands. In addition, the ear-7 mRNA is alternatively spliced to generate two protein isoforms, namely the ear71 and ear72 proteins. Nucleotide sequence analysis predicts that the ear71 protein is a human counterpart of the chicken c-erbA protein, a molecule closely related or identical to thyroid hormone receptor. Indeed, Scatchard analysis of proteins synthesized in vitro indicated very high affinity binding of T3 to the ear71 protein but not to the ear72 protein. Interestingly, the ear-1 gene product showed low, but appreciable, binding to T3, although its authentic ligand remains to be clarified.

Amino Acid Sequence↗
PubMed1989

Selective expression of a protein-tyrosine kinase, p56lyn, in hematopoietic cells and association with production of human T-cell lymphotropic virus type I.

This paper reports the identification of the lyn gene product, a member of the src-related family of protein-tyrosine kinases, and its expression in hematopoietic cells. A lyn-specific sequence (Arg-25 to Ala-119 of the protein) was expressed in Escherichia coli as a fusion protein with beta-galactosidase. Antiserum raised against the fusion protein immunoprecipitated a 56-kDa protein from human B lymphocytes. Incubation of the immunoprecipitate with [gamma-32P]ATP resulted in the phosphorylation of this protein at tyrosine residues. Immunohistological and immunoblotting analyses showed that the lyn gene product was expressed in lymphatic tissues (spleen and tonsil) and in adult lung, which contains many macrophages. Furthermore, both the transcripts and the protein products of the lyn gene accumulated in macrophages/monocytes, platelets, and B lymphocytes but were not expressed appreciably in granulocytes, erythrocytes, or T lymphocytes, suggesting that lyn gene products function primarily in certain differentiated cells of lymphoid and myeloid lineages.

Animals↗
PubMed1989

Overexpression of src family gene for tyrosine-kinase p59fyn in CD4-CD8- T cells of mice with a lymphoproliferative disorder.

Overexpression of a src family gene, lck, has been associated with differentiation of the murine thymic lymphoma line LSTRA. Recent findings by several groups strongly suggest a functional role for the gene product p56lck protein-tyrosine kinase (PTK) in the activation of normal T cells. A single recessive gene, lpr or gld, induces a lymphoproliferative disorder concomitant with autoimmune disease in mice. In this study, a 10-fold elevated activity of PTK encoded by fyn, another src family gene, was demonstrated in CD4-CD8- T cells in mutant mice. The increased PTK activity was consistent with overexpression of fyn mRNA. The elevated fyn mRNA expression appeared to be a characteristic of CD4-CD8- T cells, since it was not observed in normal T cells at any stage of differentiation. The fact that fyn mRNA expression was markedly induced in normal T cells by mitogenic stimulation with anti-T3 epsilon antiserum supports the possibility that p59fyn PTK is a signal-generating molecule in T cells. Thus, our findings provide insight into the physiological role for a src gene family kinase in T-cell development and contribute to a better understanding of the molecular mechanisms of disease-inducing recessive genes.

Animals↗
PubMed1989

Association of elevated expression of the c-erbB-2 protein with spread of breast cancer.

We analyzed amplification and expression of the c-erbB-2 gene in human breast cancers. Southern blot hybridization analysis demonstrated amplification of the c-erbB-2 gene in 10 out of 50 tumor DNAs examined. The degree of amplification was three- to twenty-fold relative to normal placenta. The c-erbB-2 protein could be analyzed in 39 tumor tissues of the 50 samples by immuno-blotting, and elevated expression of the c-erbB-2 protein was found in 15 cases. On the other hand, expression of the c-erbB-2 products was not detected in normal breast tissues either by immuno-blotting or by immuno-histological analysis. These data indicate that transcriptional and/or translational activation of c-erbB-2 might occur in some breast cancers in addition to activation by gene amplification. The elevated expression of the c-erbB-2 protein was most strongly correlated with lymph-node metastasis (P less than 0.001), suggesting that c-erbB-2 expression is involved in promotion of the lymph-node metastasis of human breast cancers. Therefore, immuno-histological diagnosis with anti-c-erbB-2 antibody might be useful as an indicator to predict lymph-node involvement in breast cancer.

Adenocarcinoma↗
PubMed1989

A murine monoclonal antibody that recognizes an extracellular domain of the human c-erbB-2 protooncogene product.

A murine IgM monoclonal antibody, designated SV2-61, was generated against human c-erbB-2 gene-transfected NIH-3T3 (SV11) cells. SV2-61 defined a 185-kDa molecule present on the surface of SV11 cells, another line of c-erbB-2 gene-transfected NIH-3T3 (A4-15) cells, and MKN-7 human gastric cancer cell line carrying an amplified human c-erbB-2 gene. The SV2-61-defined antigen was found to show protein kinase activity in vitro. The SV2-61 was reactive with human c-erbB-2 gene-transfected NIH-3T3 cell lines but not with transfectants carrying c-erbB-2 gene mutants which lack a coding region for the extracellular domain. It was reactive with a portion of human epithelial cell lines but not with native NIH-3T3, TGF-alpha-coding gene-, activated c-raf gene- or Ha-ras gene-transfected NIH-3T3 cells, or non-epithelial human cells. These results indicate that the SV2-61 is an antibody which recognizes an extracellular domain of the c-erbB-2 gene product, 185-kDa protein.

Animals↗
PubMed1989

Airway obstruction in a child with esophageal achalasia.

A 13-year-old Japanese boy who had respiratory symptoms and had been treated as a case of chronic bronchitis was found by us to have esophageal achalasia. He had complained of cough for one year and a half, and pulmonary function studies showed severe airway obstruction. The chest radiogram showed the trachea compressed by the dilated esophagus. After operation, the symptoms disappeared and marked improvement was found in the flow-volume curve. Esophageal achalasia should be considered as one of the differential diagnoses of airway obstructive disease.

Adolescent↗