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Biomedical subjects

K Toyoshima

Publications and source records attributed to K Toyoshima.

At least 253 records · Page 14Linked to original sources
PubMed1986

Activation of the cellular src gene by transducing retrovirus.

Newly isolated strains of avian sarcoma virus, S1 and S2, were shown to have the transduced cellular src gene as their viral transforming gene (Yamagishi et al., Virology 137:266-275, 1984). In this work, the S1 and S2 genomes were molecularly cloned, and the junction sequences between the viral genomes and the c-src genes and the complete nucleotide sequences of the v-src genes transduced in these viruses were determined. Data on the junction sequences suggested that 5' recombination had occurred between the 5'-noncoding region of c-src and the 5' region of the gag sequence encoding p19 in both viruses and that 3' recombination had occurred in the last coding exon of c-src with either the middle portion of the env sequence encoding gp85 for S1 or the 3' portion of pol coding for reverse transcriptase for S2. Comparison of the amino acid sequences of the S1 and S2 src products deduced from the nucleotide sequences (pp62S1-src and pp62S2-src with that of c-src protein (pp60c-src) indicated that in pp62S1-src the 8 carboxy-terminal amino acid residues of the total of 533 in pp60c-src are replaced by 43 residues translated from the env sequence at the wrong frame. In pp62S2-src, on the other hand, the 14 carboxy-terminal amino acids of pp60c-src are replaced by the 38 carboxy-terminal residues of reverse transcriptase. The mechanism of c-src transduction and the structural changes necessary for pp60c-src activation are discussed.

Animals↗
PubMed1986

High incidence of amplification of the epidermal growth factor receptor gene in human squamous carcinoma cell lines.

Southern blot-hybridization analysis of DNAs from human tumors demonstrated amplification of the epidermal growth factor (EGF) receptor gene in 10 of 12 squamous cell carcinoma cell lines tested and in none of 18 tumor cell lines of nonsquamous cell carcinomas. The degree of amplification in the squamous cells varied from 2- to 50-fold relative to the epidermal keratinocyte. Hybridization analysis of the RNA showed that the amplification of the EGF receptor gene is accompanied with an increase of the 5.6 kilobases of EGF receptor mRNA. Scatchard plot analysis and sodium dodecyl sulfate-polyacrylamide gel analysis of the EGF receptor revealed that the synthesis of the EGF receptor is also greater in the cells with amplified EGF receptor gene. In contrast, Southern blot analysis of DNAs of primary tumors showed that incidence of amplification of the EGF receptor gene in squamous cells (1 of 6) was almost as frequent as in nonsquamous cells (1 of 4). These results show that amplification of the EGF receptor gene is commonly found in various tumors. In addition, our data suggest that primary squamous cell carcinomas with amplified EGF receptor gene may readily adapt to growth in tissue culture.

Carcinoma, Squamous Cell↗
PubMed1986

Modification of carboxyl-terminal region is the cause of activation of the src gene in avian sarcoma virus S2.

Viral oncogene product of avian sarcoma virus S2 was reported to have two alterations from proto-src product; a substitution of its extreme carboxyl terminus with a peptide of helper viral protein and a point mutation which altered the 501st amino acid from arginine to lysine. However, the following data suggest that lysine501 is more common in proto-src product than arginine501. Proto-src from two independent embryos which we analyzed encoded lysine for the 501st amino acid. Rous sarcoma virus and S1, another isolate which had transduced proto-src, also coded for lysine at the same position. Thus, in the case of S2, the oncogenic activation of the src gene appeared to be achieved with only an alteration at its carboxyl terminus and enhanced expression by long terminal repeats.

Amino Acid Sequence↗
PubMed1986

DNA amplification of the c-myc and c-erbB-1 genes in a human stomach cancer.

High-molecular-weight DNAs from 43 human primary tumor tissues were examined by Southern blot hybridization for possible rearrangement and/or amplification of the following protooncogenes: the c-myc, c-erbB-1, N-myc, c-mos and c-fos genes. In an adenosquamous cell carcinoma of the stomach, the c-myc and c-erbB-1 genes were found to be simultaneously amplified 5- and 30-fold, respectively. Cooperative expression of the amplified c-myc and c-erbB-1 genes might be involved in the genesis or progression of the gastric cancer.

DNA, Neoplasm↗
PubMed1986

Nakahara memorial lecture. Non-receptor type protein-tyrosine kinases closely related to src and yes compose a multigene family.

We have determined the total coding sequence of human c-yes, a non-receptor type protein-tyrosine kinase gene, and found that the c-yes gene closely resembles the c-src gene. Recently, two new genes, syn and lyn, were found to encode proteins closely related to the yes product. In addition, we also determined the partial sequence of fgr. These genes together with lck reported by two American groups have very closely related structures and are thought to compose a closely related group of non-receptor type protein-tyrosine kinases. Partial analysis of the structures of these genes indicated that they have identical splicing junctions at all sites so far examined. On the other hand, the erbB-1/EGF (epidermal growth factor) receptor gene and the erbB-2/neu gene have completely different splicing junctions from those of the above gene group even in the kinase domain, although these genes also have protein kinase activity specific for tyrosine residues and the erbB-1 and -2 genes share splicing sites. These results suggest that the genes of the group of six non-receptor type kinases and those of the erbB-1 and erbB-2 gene group are descendants evolved by duplication of two distinct ancestor genes and are members of two distinct multi-gene families. The genes coding for protein kinases may be members of a super-family including multiple distinct gene families.

Amino Acid Sequence↗
PubMed1986

Expression of the c-erbB-2 gene encoding a growth factor receptor.

The c-erbB-2 gene is a v-erbB-related proto-oncogene which encodes a protein similar to but distinct from the epidermal growth factor (EGF) receptor. In situ hybridization of metaphase spread showed that this gene is located on human chromosome 17 at q21, a specific breakpoint observed in a translocation associated with acute promyelocytic leukemia. The c-erbB-2 DNA probe hybridized with a 4.6 kb mRNA which directs the synthesis of a 185 kd glycoprotein. The 185 kd c-erbB-2 protein is associated with tyrosine kinase activity and is possibly phosphorylated by C-kinase on its serine and threonine residues. In addition, the c-erbB-2 protein is suggested to be a substrate for EGF receptor tyrosine kinase, since EGF binding to the EGF receptor rapidly induced phosphorylation of the c-erbB-2 protein on its tyrosine residue. Southern blot hybridization analysis of DNAs from human tumors demonstrated amplification of the c-erbB-2 gene restricted to adenocarcinomas. Finally, the promoter of the c-erbB-2 gene contains the typical TATA box and CAAT box as well as a GC box-like sequence. This is in contrast with the promoter of the EGF receptor gene, since the latter contains only GC-boxes. Therefore, it is suggested that the two genes are under different transcriptional control.

Amino Acid Sequence↗
PubMed1986

Ultrastructure of von Ebner's salivary glands in the rabbit.

The von Ebner's salivary glands associated with the vallate and foliate papillae of the rabbit tongue were studied by light and electron microscopy. The glands are tubulo-alveolar in structure and have an abbreviated duct system. The seromucous cells of the secretory end-pieces contain numerous granules with a complex substructure; when the granule matrix is partially extracted as the result of less-than-optimal fixation, these granules are seen to contain bundles of 17-18 nm filaments. The ductular epithelium undergoes progressive change from simple columnar to stratified cuboidal or columnar. Both of these duct segments contain secretory granules that differ from those in the tubulo-alveolar cells and from each other. Thus the constituent cells of leporine von Ebner's glands produce a variety of organic secretory products.

Animals↗
PubMed1985

Location of the c-yes gene on the human chromosome and its expression in various tissues.

Analysis of DNA from human embryo fibroblasts showed that ten Eco RI fragments were hybridizable with the Yamaguchi sarcoma virus oncogene (v-yes). Four of the Eco RI fragments were assigned to chromosome 18 and one to chromosome 6. There was evidence for multiple copies of yes-related genes in the human genome; however, only a single RNA species, 4.8 kilobases in length, was related to yes in various cells.

Animals↗
PubMed1985

Translocation chromosome 7 of A431 cells contains amplification and rearrangement of EGF receptor gene responsible for production of variant mRNA.

The epidermal growth factor (EGF) receptor, along with several oncogene protein products, possesses tyrosine-specific protein kinase activity. Furthermore, the EGF receptor has structural similarity to the putitive v-erb-B transforming protein. Because of these closely shared characteristics, it is important to elucidate the possible involvement of the EGF receptor in malignant transformation. The epidermal carcinoma cell line A431 exhibits an abnormally high number of EGF receptors, which is associated with the presence of translocation chromosome M4. Recently, A431 cells have been shown to contain amplified sequences for the EGF receptor gene(s) and also to produce a variant mRNA which diverges from the normal EGF receptor mRNA at the 3' end. Here we report, using the human EGF receptor cDNA probe pE7, that the chromosome M4 has a six- to sevenfold amplification of the EGF receptor gene. Furthermore, the presence of M4 in somatic cell hybrids correlates with the production of the variant 2.9-kb mRNA. This aberrant mRNA is apparently generated by an intrachromosomal rearrangement which was detected using as a probe a fragment of the pE15cDNA encoding the variant mRNA.

Animals↗
PubMed1985

Detection of a raf-related and two other transforming DNA sequences in human tumors maintained in nude mice.

High molecular weight DNAs prepared from a variety of human tumors maintained in nude mice were assayed for their ability to transform NIH 3T3 cells. DNAs from 4 of 21 tumors tested induced transformed foci in cultures of NIH 3T3 cells. They were from a Ewing sarcoma line, a glioblastoma line, a leiomyosarcoma line, and a lung carcinoma line. Hybridization analyses of the NIH 3T3 transformant DNAs with a human repetitive sequence as probe revealed that four distinct transforming DNA sequences were transferred to NIH 3T3 cells from the four tumor lines. The transforming DNA in a lung carcinoma line was a human homologue of the oncogene of Kirsten murine sarcoma virus (Ki-ras). On the other hand, the three other transforming DNAs showed no similarity to any known human transforming gene detected by the NIH 3T3 transformation assay. Further analyses with a series of cloned oncogenes as probes revealed that the transforming DNA in a glioblastoma line was a human homologue of the oncogene of 3611-murine sarcoma virus (raf). However, the two transforming DNAs in a Ewing sarcoma line and a leiomyosarcoma line had no sequence homology to any of the cloned oncogenes.

Animals↗
PubMed1985

A v-erbB-related protooncogene, c-erbB-2, is distinct from the c-erbB-1/epidermal growth factor-receptor gene and is amplified in a human salivary gland adenocarcinoma.

From a human genomic library, we obtained six v-erbB-related DNA clones. A DNA probe prepared from one of the clones, lambda 107, hybridized to EcoRI fragments of 6.4 and 13 kilobase pairs of human DNA. Neither of these fragments was amplified in A431 vulva carcinoma cells, in which the gene encoding the epidermal growth factor receptor is amplified. In addition, the probe from lambda 107 hybridized with a single, 4.8-kilobase poly(A)+ RNA species and did not react with EGF receptor mRNA. Thus, we conclude that clone lambda 107 represents a v-erbB-related gene (c-erbB-2) that is distinct from the EGF receptor gene. In contrast, the other five clones were shown to represent the EGF receptor gene (c-erbB-1). Partial nucleotide sequence analysis of the lambda 107 insert showed that this clone contained at least seven putative exons and that six of them could encode the kinase domain characteristic of protein products of the src oncogene family. Southern blot analysis showed close similarity of the restriction patterns of the rat c-erbB-2 gene and the rat neu oncogene, suggesting possible involvement of c-erbB-2 in human cancer. In fact, approximately 30-fold amplification of c-erbB-2 was observed in a human adenocarcinoma of the salivary gland.

Adenocarcinoma↗
PubMed1985

Two independent mutations are required for temperature-sensitive cell transformation by a Rous sarcoma virus temperature-sensitive mutant.

We molecularly cloned the src coding region of tsNY68, a mutant of Rous sarcoma virus temperature sensitive (ts) for transformation, and constructed a series of ts wild-type recombinant src genes. DNA containing the hybrid genes was transfected into chicken cells together with viral vector DNA and helper viral DNA, and infectious transforming viruses were recovered. Characterization of these recombinant viruses indicated that at least two mutations are present in the 3' half of the mutant src gene, both of which are required for ts. Nucleotide sequence analysis revealed three differences in the deduced amino acid sequence compared with the parental virus. Two of these changes, a deletion of amino acids 352 to 354 and an amino acid substitution at position 461, are responsible for the ts phenotype.

Animals↗
PubMed1985

[A member of the SRC gene family, the c-erbB-1 gene, is closely related to the EGF receptor gene].

An avian erythroblastosis virus, AEV-H, induces both erythroblastosis and sarcomas in susceptible chickens. Since AEV-H carries the v-erbB as a sole oncogene, the erbB gene was suggested to be responsible for the induction of these tumors. Analysis of the amino acid sequence predicted from the nucleotide sequence of the v-erbB gene revealed that the gene product has a domain characteristic for tyrosine kinase. Recently in has been suggested has the v-erbB protein is a part of the chicken EGF (epidermal growth factor) receptor. Using antibody against either v-erbB protein or EGF receptor, we also demonstrated close similarity between the two proteins. Further studies on human genomic DNA revealed that the c-erbB-1 gene, a proto-oncogene of the v-erbB gene, is the EGF receptor gene. We were also able to identify the c-erbB-2 gene that seems to code for a EGF receptor-like protein with a domain for tyrosine kinase. Finally, we would like to show that cell lines established from human squamous cell carcinom are frequently associated with amplification of the c-erbB-1/EGF receptor gene.

Alpharetrovirus↗
PubMed1985

Human c-f gr gene does not contain coding sequence for actin-like protein.

f gr is a member of the protein kinase oncogene family and was found to have the highest homology to yes gene among the members of the family. Using a v-yes probe, a molecular clone of human c-f gr locus was isolated from a genomic library. Nucleotide sequence determination revealed that the actin gene-like sequence found in v-f gr gene was absent at the corresponding position of the c-f gr gene. Thus, the v-f gr gene product is considered to be a tri-chimeric gene product consisting of viral gag gene and two distinct cellular genes, actin gene and the proto-f gr gene.

Actins↗
PubMed1985

Regional mapping of the human proto-oncogene c-yes-1 to chromosome 18 at band q21.3.

Human proto-oncogene c-yes-1 homologous to the viral oncogene (v-yes) of an avian Y73 sarcoma virus was mapped to region q21.3 of chromosome 18 by in situ hybridization. This finding confirmed and more rigidly substantiated the previous assignment which was based on analyses of human X mouse somatic cell hybrids and Southern blots.

Chromosome Mapping↗
PubMed1984

Amplification and enhanced expression of the epidermal growth factor receptor gene in A431 human carcinoma cells.

The sequence of the human epidermal growth factor (EGF) receptor shows great homology with the avian erythroblastosis virus v-erb B oncogene, raising the possibility that the receptor gene is identical to the c-erb B protooncogene. Human A431 epidermoid carcinoma cells, which have an unusually high number of EGF receptors, were examined to determine whether elevated EGF receptor levels correlate with gene amplification. Southern blots of genomic DNA's from A431 and other human cell lines were probed with either a v-erb B gene fragment or a human EGF receptor complementary DNA clone (pE7), previously isolated from an A431 complementary DNA library. When either probe was used to analyze Eco RI- or Hind III-generated DNA fragments, EGF receptor DNA sequences were amplified about 30-fold in A431. Differences in the banding pattern of A431 DNA fragments relative to normal fibroblast DNA indicate the occurrence of a rearrangement in the region of the receptor gene. Furthermore, A431 cells contain a characteristic, prominent 2.9-kilobase RNA. These results are consistent with the hypothesis that, in A431 cells, gene amplification, possibly associated with a translocation event, may result in the overproduction of EGF receptor protein or the appearance of the transformed phenotype (or both).

Alpharetrovirus↗