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PubMed1988

[Oncogenes and the origin of leukemia. Acute avian leukemia viruses].

Oncogenes have been intimately associated with the genesis of human neoplasms. A particularly useful system to study the mechanism of tumorigenesis is a small group of avian retroviruses that carry two oncogenes. These viruses causes acute leukemias and can transform hematopoietic cells in vitro. The mechanisms by which viral oncogenes affect the growth control and differentiation of their target cells is now understood in fair detail for two of these virus strains. In the avian erythroblastosis virus AEV, the v-erbB oncogene deregulates the growth control of erythroid precursors, while verbA blocks their terminal differentiation into erythrocytes. Based on the findings that v-erbB oncogene corresponds to a mutated growth factor receptor gene and that v-erbA corresponds to a mutated hormone receptor gene, models have been developed that explain the function of these two oncogenes on a molecular basis. The myelomonocytic leukemia virus MH2 acts by a completely different mechanism. In this case, the v-myc oncogene stimulates the proliferation of macrophage-like cells, while the v-mil gene stimulates them to produce their own growth factor, thus leading to autocrine growth. It will be interesting to determine whether the type of mechanisms of oncogene cooperativity elucidated for acute leukemia viruses are also operative during leukemogenesis in humans.

Alpharetrovirus↗
PubMed1986

The erbB gene and the EGF receptor.

The epidermal growth factor (EGF) receptor is a plasma membrane glycoprotein. It contains four distinct segments: an N-terminal EGF binding domain which is exposed at the cell surface; a short transmembrane segment; a cytoplasmic domain with protein-tyrosine kinase activity; and a C-terminal regulatory segment. Binding of EGF to the external domain of the receptor activates the protein-tyrosine kinase activity of the receptor, and this elevated kinase activity is presumed to be involved in the activation of cell growth. The v-erbB transforming gene of avian erythroblastosis virus is derived, by retroviral transduction, from the gene (c-erbB) which encodes the avian EGF receptor. The transforming capacity of v-erbB appears to result from truncation of the receptor. In erythroid cells, truncation of the N-terminal ligand binding domain is sufficient for transformation, whereas in fibroblasts removal of an additional C-terminal segment is required for transformation. The EGF receptor is subject to complex regulatory controls, including ligand activation, downregulation by internalization, autophosphorylation and autoregulation and transmodulation involving phosphorylation by kinase C. This review is centered around the hypothesis that the transforming capacity of the truncated v-erbB gene product results from a loss in sensitivity to regulators and the consequent activation of protein kinase activity.

Alpharetrovirus↗
PubMedDate not supplied

HIV and HTLV-I antibody studies: pregnant women in the 1960s, patients with AIDS, homosexuals, and individuals with tropical spastic paraparesis.

To investigate the possible occurrence of human immunodeficiency virus (HIV) or human T-cell lymphotropic virus, type I (HTLV-I) infections in the United States prior to 1979-1981, when acquired immune deficiency syndrome (AIDS) was first recognized, we tested sera from 310 pregnant women who participated in the Collaborative Perinatal Project during the period 1959-1964 for HIV and HTLV-I antibody. These samples included sera from 53 pregnant women who were intravenous drug users. The remainder were from women who had cervical epithelial abnormalities, who developed cervical carcinomas, who had had children with erythroblastosis fetalis, who had had children that developed malignant neoplasms early in life, or normal pregnant women. None of the 310 women had confirmed HIV or HTLV-I antibody. The rate of false-positive reactions with the HIV enzyme-linked immunosorbent assay (ELISA) antibody test in these long-frozen samples was similar to that observed in fresh sera. HIV antibody was detected in homosexual patients with AIDS; HTLV-I antibody was not detected in any of these sera. HTLV-I antibody was detected in 17 of 20 patients with tropical spastic paraparesis (TSP) and in two of seven patients with other neurological diseases diagnosed as transverse myelopathy and multiple sclerosis, and in none of nine normal controls; HIV antibody was not detected in any of these sera patients. Thus, we conclude that there was no serological evidence of infection with HIV or HTLV-I in the pregnant women studied; however, HIV antibody was present in all AIDS patients tested, and HTLV-I antibody was found in the majority of patients with TSP.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Effects of Friend leukemia virus (FLV) inoculation in F1 mice and differentiation of FLV-induced leukemia.

Effects of Friend leukemia virus (FLV) inoculation in F1 specific pathogen free (SPF) mice were examined. Resistance to FLV was dominantly inherited both in F1 hybrid mice (BDF1) (FLV-resistant & FLV-sensitive with polycythemia) and F1 hybrid mice (B6C3F1) (FLV-resistant & FLV-sensitive with anemia). But the population dynamics of the nucleated cell components of F1 mice after FLV inoculation differed from those of FLV-resistant inbred mice. A small number of mature erythroblasts appeared in the peripheral blood of BDF1 mice. In B6C3F1 mice, erythroblastosis with splenomegaly and polycythemia occurred. However, all of these findings in BDF1 and B6C3F1 mice regressed spontaneously. In F1 mice, FLV induced an intermediate reactive pattern of the two patterns that had been induced in the parental strains. The results indicate that FLV may induce leukemia with various degrees of differentiation, according to the genetic difference of the host.

Animals↗
PubMed1977

Genetic control of antinuclear antibodies in mice infected with Rauscher leukemia virus.

The incidence of antinuclear antibodies after Rauscher leukemia virus inoculation was found to be significantly higher in C57BL/6 than in BALB/c mice and still greater in their F1 hybrids. The relationships among antinuclear antibody incidence, erythroblastic disease, Rauscher leukemia virus production, and the H-2 genotypes were studied in the F1 generation and backcrosses using different virus inocula. The results observed suggest that (a) at least two genes are involved in the control of susceptibility to Rauscher leukemia virus-induced erythroblastosis, one of them probably being H-2 linked, and that (b) a non-H-2-linked gene seems to control, at the same time, induction of antinuclear antibodies, focus-forming virus production in the spleen, and susceptibility to the disease. It can be concluded that C-type viruses play an active role in antinuclear antibody induction.

Animals↗
PubMedDate not supplied

[A preparation of short DNA chains synthesized in vivo after introduction into DNA from live cells of trioxsalen crosslinks is not enriched by replication initiation regions].

The experiments undertaken in order to verify the trioxsalen-crosslinking method suggested by Russev and Vassilev for isolation of eukaryotic replication origins are described. It was found that the preparation of viral DNA isolated by the above mentioned method from CV-1 cells lytically infected with SV40 was not enriched in sequences including SV40 replication origin. The hybridization pattern of DNA preparation isolated by the trioxsalen-crosslinking procedure from chicken erythroblastosis cells with the cloned fragments of globin gene domain was found to be identical to those of the total DNA probe. The DNA fraction enriched in replication origins was isolated from the same cells with the aid of nascent DNA strand extrusion method by Zannis-Hadjopoulos et al. The hybridization pattern of this DNA fraction with the cloned fragments of chicken alpha-globin gene domain was different from those of total DNA. Taking together, the results of our experiments demonstrate that trioxsalen-crosslinking procedure does not lead to the isolation of replication origins from the objects studied in the present investigation.

Animals↗
PubMedDate not supplied

[Spatial organization of replicons in the eukaryotic nucleus: attachment of replication initiation regions to the nuclear skeleton].

The DNA fraction enriched in replication origins was isolated from chicken erythroblastosis cells with the aid of nascent DNA strand extrusion method. In renaturation experiments, the sequence specificity of this DNA fraction (oriDNA) was compared to the sequence specificity of the nuclear matrix DNA. The oriDNA was shown to comprise a specific subset of unique genes all of which being represented also in the nuclear matrix DNA. The same unique DNA sequences were found to be depleted from the oriDNA and from the nuclear matrix DNA. A conclusion has been drawn that replication origins are located at the basements of DNA loops. The putative positions of replication origins within the domain of chicken alpha globin genes were mapped by hybridization experiments and were found to coincide with the positions of stable (not depending on the transcriptional state of globin genes) sites of DNA attachment to the nuclear skeleton.

Animals↗
PubMedDate not supplied

The avian and mammalian ets genes: molecular characterization, chromosome mapping, and implication in human leukemia.

The mammalian homologs of the ets-region from the transforming gene of avian erythroblastosis virus, E26, consist of two distinct domains located on different chromosomes. Using somatic cell hybrid panels, the mammalian homologs of the 5' v-ets-domain, ets-1, were mapped to chromosome 11 in man, to chromosome 9 in mouse, and to chromosome D1 in cat. The mammalian homologs of the 3'v-ets domain, ets-2, were similarly mapped to human chromosome 21, to mouse chromosome 16, and to feline chromosome C2. We conclude that the ets sequence shared by the virus, chicken, and man is likely to contain at least two functionally dissociable domains, identifiable as ets-1 and ets-2. The human ets- locus is transcriptionally active and encodes a single mRNA of 6.8 kb, while the second locus, human ets-2 encodes three mRNAs of 4.7, 3.2 and 2.7 kb. By contrast, the chicken homolog, having a contiguous ets-1 and ets-2 sequence, is primarily expressed in normal chicken cells as a single 7.5 kb mRNA. Because chromosome translocations have been associated with different human hematopoietic malignancies, we have used our human probes to study specific translocations occurring in acute leukemias. The human ets- gene was found to translocate from chromosome 11 to 4 in t(4;11) (q21;23) and the human ets-2 gene was found to translocate from chromosome 21 to 8 in t(8;21) (q22;q22). Significantly, both translocations were associated with an expression of ets genes which differed from that found in normal diploid lymphoid cells.

Acute Disease↗
PubMed1988

Complementary DNA clones of chicken proto-oncogene c-ets: sequence divergence from the viral oncogene v-ets.

The avian acute leukemia virus E26 induces erythroblastosis and myeloblastosis in chickens. The oncogene of this virus includes sequences derived from the cellular gene designated c-ets, which is normally expressed in lymphoid cells and whose product is a protein of apparent molecular weight ca. 54,000 daltons. Complementary DNA clones representing the major transcript of the chicken c-ets proto-oncogene were isolated from a spleen cell library. Sequence analysis of the cDNA revealed that it contains an open reading frame encoding a polypeptide of 441 amino acids with a molecular weight of 49,932 daltons. This open reading frame can be transcribed and translated in vitro into a 50 kd protein that is specifically immunoprecipitated with antiserum to the v-ets oncogene product. Within the central region of homology between c-ets and v-ets, there are only 5 nucleotide substitutions resulting in 4 amino acid changes. However, coding sequences at the 5' and 3' ends of the v-ets oncogene and the chicken c-ets cDNA differ from one another. These changes may be responsible for the differential functions of c-ets and v-ets in cells of different hematopoietic lineages and may account for the pathogenic properties of the v-ets oncogene.

Amino Acid Sequence↗
PubMed1988

Adenosine deaminase (ADA) overproduction associated with congenital hemolytic anemia: case report and molecular analysis.

We report the fourth case of adenosine deaminase (ADA) overproduction associated with hereditary nonspherocytic hemolytic anemia and the molecular analysis of this anomaly. The proband was a 10-year-old Japanese boy, who had an episode of erythroblastosis fetalis during the perinatal period. The red cell ADA activity showed a 110-fold increase and the red cell ATP level was about 64% of the comparably reticulocyte-rich controls, but the lymphocyte ADA activity was within the normal range. Western blotting of partially purified ADA from red cells revealed an increased amount of enzyme in the patient's red cells. No gene amplification or gene rearrangement was found by Southern blot analysis, and no increase of ADA mRNA in reticulocyte RNA was detected by dot blot analysis using ADA cDNA. We constructed a genomic DNA library and obtained three clones containing the 5'-promoter region of ADA gene. The 2.2 kb ADA promoter DNA fragment of these clones was fused to the chloramphenicol acetyl transferase (CAT) gene, and transfected to human erythroid cell line K562, and assayed for CAT activity. One of the clones, pADOP 2 cat, expressed about 2.6 times higher CAT activity than the normal ADA promoter fused to CAT gene in K562, but such enhancement was not seen in human non-erythroid cell lines; HL 60 and Raji. From these results, it is most likely, though not conclusive, that the 5' promotor fragment of the ADA gene of the patient was responsible for the cell-specific enhancement of protein synthesis.

Adenosine Deaminase↗
PubMed1988

[The antineoplastic activity of testiphenon].

The paper describes the antitumor activity of a newly-developed hormonocytostatic drug testiphenon--a complex ether of 5 alpha-dihydrotestosterone and chlorphenacyl (17 beta-[n-di/2-chloroethyl/aminophenylacetate]-5 alpha-androstan-17 beta-ol-3-on). Its antitumor properties were studied in 15 models of transplantable solid tumors and systemic neoplasms of mice and rats such as sarcoma 298, sarcoma 37, sarcoma-180, Lewis lung epidermoid carcinoma, carcinoma of the forestomach-5, large bowel adenocarcinoma, Harding-Passey's melanoma, cervical cancer-5, mammary adenocarcinoma Ca-755, hemoblastosis La, plasmacytoma MOPC-406, Rauscher's erythroblastosis, Walker's carcinosarcoma 256, sarcoma 45, alveolar carcinoma of the mammary gland and DMBA-induced mammary tumors of mice. The spectrum of antitumor activity of testiphenon proved wider than those of its components or other estrogeno-cytostatic drugs--phenestrol and estracyt. The drug is specifically intended for selective action upon target tissues for androgens and tumors developing from the said tissues.

Animals↗
PubMed1988

Characterization and localization of the products of the human homologs of the v-ets oncogene.

The avian erythroblastosis virus, E26, an acute leukemia virus, contains a transforming gene composed of two cellular components, v-myb and v-ets. The v-ets related sequences of man and other mammals consist of two transcriptionally active genes, ets-1 and ets-2, located on separate chromosomes. By contrast, both of these genes are contiguous in birds, are located on the same chromosome, and are coordinately transcribed. The human ets-1 and ets-2 gene products were identified by means of antibodies directed against the ets-1 and ets-2 encoded products. A 51 kD protein has been identified as the ets-1 gene product, and a 56 kD protein as the ets-2 gene product. Cellular fractionation studies indicated that the ets-1 protein is located in the cytoplasm and the ets-2 protein is nuclear. By comparison, the chicken ets protein, which contains both the ets-1 and ets-2 domains, distributes equally between the cytoplasm and nucleus. The differential compartmentalization of the ets gene products and their non-coordinate expression suggest that these proteins have different biological functions.

Cell Compartmentation↗
PubMed1986

Two new retroviral onc genes, sea and jun.

Avian leukemia virus S13 induces erythroblastosis, granulocytic leukemia, fibrosarcoma, anemia, and endothelial neoplasia. It transforms chick embryo fibroblasts and primitive erythroid cells in culture and is defective in replication. Its onc gene, sea, is expressed as transformation specific env-sea fusion glycoprotein of 155 kDa. Gp155 is proteolytically processed into gp85env and gp70env-sea. The latter shows tyrosine specific protein kinase activity. Avian sarcoma virus 17 induces fibrosarcoma and transforms chick embryo fibroblasts in culture. Its cell derived onc gene, jun, is not related to known onc genes and appears to be expressed as a gag-jun fusion protein of 55 kDa. The amino acid sequence of jun shows homology in its C-terminal region to the C-terminal DNA binding region of the yeast regulatory protein GCN4, suggesting that the jun protein may bind to DNA.

Amino Acid Sequence↗
PubMed1986

Molecular evolution of ets genes from avians to mammals and their cytogenetic localization to regions involved in leukemia.

The mammalian homologues of the ets-region from the transforming gene of avian erythroblastosis virus, E26, consists of two distinct domains located on different chromosomes. Using somatic cell hybrid panels, the mammalian homolog of the 5' v-ets-domain (ets-1) was mapped to chromosome 11 in man, to chromosome 9 in mouse, and to chromosome D1 in cat. The mammalian homolog of the 3' v-ets domain (ets-2) was similarly mapped to human chromosome 21, to mouse chromosome 16, and to feline chromosome C2. To better define the human proto-ets domains, the genomic DNA was molecularly cloned and sequences analyzed. The ets-related sequences of human DNA on chromosomes 11 and 21 were found to be discontiguous, unlike that of the chicken and avian E26 virus genome, except for a small overlap region. We conclude that the ets sequence shared by the virus, the chicken and man is likely to contain at least two dissociable functional domains, identifiable as ets-1 and ets-2. The human ets-1 locus is transcriptionally active and encodes a single mRNA of 6.8 kb, while the second locus, human ets-2 encodes three mRNAs of 4.7, 3.2 and 2.7 kb. By contrast, the chicken homolog, having a contiguous ets-1 and ets-2 sequence, is primarily expressed in normal chicken cells as a single 7.5 kb mRNA. Because chromosome translocations have been associated with different human disorders, we have used our human probes with two panels of rodent-human cell hybrids to study specific translocations occurring in acute myeloid leukemias (AML). The human ets-1 gene was found to translocate from chromosome 11 to 4 in t(4;11)(q21;q23) and the human ets-2 gene was found to translocate from chromosome 21 to 8 in t(8;21)(q22;q22). Both translocations were found associated with the altered expression of ets.

Amino Acid Sequence↗
PubMed1988

Histogenesis and clonality of pancreatic tumors induced by v-myc and v-raf oncogenes in NFS/N mice.

Newborn NFS/N mice were inoculated with pseudotypes of murine retroviruses containing murine v-raf, avian v-myc, or both v-raf and v-myc within a single construct. Foci of dysplastic acinar cells, similar to those observed in rats given chemical carcinogens, were induced in 77% of mice inoculated with the raf/myc construct with a latency as short as 15 days. However, all animals given this construct also developed fibrosarcomas, erythroblastosis, and lymphomas and died within 70 days of infection, before pancreatic acinar carcinomas developed. Dysplastic foci were also observed in mice infected with viruses containing v-raf or v-myc alone with latencies of 3-4 weeks, and carcinomas were seen after an average latency of 150 days in 31% of mice infected with either of two viruses expressing v-myc alone. Two primary carcinomas were transplanted in mice, and in vitro cell lines were developed from one of the transplants. DNA prepared from seven primary carcinomas, the two transplanted tumors, and the in vitro cell lines was hybridized with a v-myc probe. Each tumor had a unique pattern of proviral integrations that was retained, with the gain or loss of single sites, in the transplants and derivative cell lines. The clonal nature of the advanced pancreatic acinar carcinomas is discussed in relation to their histogenesis and the transforming potentials of the raf and myc oncogenes.

Animals↗
PubMed1986

[Heterogeneity of the effectors of natural killer activity in CBA mice].

The natural cytotoxicity of Percoll fractions of CBA mice splenocytes was tested against cells of human erythroblastosis suspension culture K-562 and murine C3HA hepatoma solid culture MGXXIIa. The 1.076 g/ml dense fraction was shown to have the highest activity in 3H-uridine cytotoxic test against the cell targets. Immunosera prepared by the Golub method against CBA mouse brains and exhausted supplementary by syngeneic thymocytes decreased the natural cytotoxicity of CBA mouse splenocytes against MGXXIIa tumor cells and, on the contrary, increased it against K-562 tumor cells.

Animals↗
PubMed1987

A unique gene for 5-aminolevulinate synthase in chickens. Evidence for expression of an identical messenger RNA in hepatic and erythroid tissues.

Reports to date have led to the conclusion that there are isozymes for 5-aminolevulinate synthase in the liver and erythroid tissue of chicken. Indeed, the existence of a multigene family for chicken 5-aminolevulinate synthase has been proposed. We find no evidence to support these proposals. In this work we show that 5-aminolevulinate synthase mRNA from chicken liver and reticulocytes is identical as determined by RNase mapping and primer extension studies and that the 5-aminolevulinate synthase protein from these tissues is the same size as judged by immunoblot analysis. We also show that a single mRNA species for 5-aminolevulinate synthase is present in chicken liver, reticulocytes, brain, and heart and an avian erythroblastosis virus-transformed chicken erythroblast cell line. Southern analysis shows the presence of only one gene copy for 5-aminolevulinate synthase in the chicken haploid genome. Overall, these results lead to the conclusion that in chickens 5-aminolevulinate synthase is encoded by a unique gene and is expressed as a single mRNA species in all tissues.

5-Aminolevulinate Synthetase↗
PubMed1987

Molecular structure of the avian and mammalian ets genes.

The ets gene was originally identified as a second cell derived sequence transduced by the avian transforming retrovirus, E26. E26 induces erythroblastosis and myeloblastosis in chickens and transforms erythroblasts and myeloid cells in culture. From sequence analysis of the cloned provirus, the p135 transforming protein was found to be tripartite, with gag, myb and ets sequences. We have determined the nucleotide sequence of the v-ets homologous regions contained in chicken genomic clones which define nine domains. Two of these domains are not transcribed and thus do not represent functional exons. To further explore the function of the ets gene, we have begun characterization of the mammalian ets genes. Unlike the chicken gene, the mammalian ets genes are present on two chromosomes. The mammalian homologs of the 5' v-ets domain, ets-1, were mapped to chromosome 11 in man, to chromosome 9 in mouse, and to chromosome D1 in cat. The homologs of the 3' v-ets domain, ets-2, were mapped to human chromosome 21, to mouse chromosome 16, and to feline chromosome C2. The assignment of the ets-2 gene to the Down syndrome associated chromosome 21 may have interesting implications. This oncogene, ets has been connected with leukemias in chickens, and therefore might have a role in the increased frequency of leukemias in Down patients.

Amino Acid Sequence↗