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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A naturally occurring feline thymic lymphosarcoma (T17) provided the unique observation of a T-cell antigen receptor beta-chain gene (v-tcr) transduced by a retrovirus. The primary tumor contained three classes of feline leukemia virus (FeLV) provirus, which have now been characterized in more detail as (i) v-tcr-containing recombinant proviruses, (ii) v-myc-containing recombinant proviruses, and (iii) apparently full-length helper FeLV proviruses. The two transductions appear to have been independent events, with distinct recombinational junctions and no sequence overlap in the host-derived inserts. The T17 tumor cell line releases large numbers of FeLV particles of low infectivity; all three genomes are encapsidated, but passage of FeLV-T17 on feline fibroblast and lymphoma cells led to selective loss of the recombinant viruses. The oncogenic potential of the T17 virus complex was, therefore, tested by infection of neonatal cats with virus harvested directly from the primary T17 tumor cell line. A single inoculation of FeLV-T17 caused persistent low-grade infection culminating in thymic lymphosarcoma and acute thymic atrophy, which was accelerated by coinfection with the weakly pathogenic FeLV subgroup A (FeLV-A)/Glasgow-1 helper. Molecularly cloned FeLV-tcr virus (T-31) rescued for replication by a weakly pathogenic FeLV-A/Glasgow-1 helper virus was similarly tested in vivo and induced thymic atrophy and thymic lymphosarcomas. Most FeLV-T17-induced tumors manifested either v-myc or an activated c-myc allele and had undergone rearrangement of endogenous T-cell antigen receptor beta-chain genes, supporting the proposition that the oncogenic effects of c-myc linked to the FeLV long terminal repeat are targeted to a specific window in T-cell differentiation. However, neither the FeLV-T17-induced tumors nor the T-31 + FeLV-A-induced tumors contained clonally represented v-tcr sequences. Only one of the FeLV-T17-induced tumors contained detectable v-tcr proviruses, at a low copy number. While v-tcr does not have a readily transmissible oncogenic function, a more restricted role is not excluded, perhaps involving antigenic peptide-major histocompatibility complex recognition by the T-cell receptor complex. Such a function could be obscured by the genetic diversity of the outbred domestic cat host.
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PMID:Pathogenesis of feline leukemia virus T17: contrasting fates of helper, v-myc, and v-tcr proviruses in secondary tumors. 131 66

The nonpathogenic human defective parvovirus adeno-associated virus (AAV) type 2 induced differentiation-associated antigens in cells of the human leukemia cell line HL60 (CD 67), as well as in two different lines of immortalized human keratinocytes, HaCaT and HPK Ia cells (involucrin and cytokeratin 10). Simultaneously, expression of the c-myc and c-myb oncogenes and the retinoblastoma gene was down regulated whereas c-fos expression increased in infected cells. These data point to the potential of AAV to induce functions related to the differentiation pathway in different types of human cells. This phenomenon may be involved in the reported oncosuppressive properties of AAV infections.
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PMID:Induction of differentiation-associated changes in established human cells by infection with adeno-associated virus type 2. 131

Epstein-Barr-virus- (EBV-) positive lymphoblastoid cell lines (LCLs) spontaneously arising in vitro were obtained from the peripheral blood of six HIV-seropositive patients and from the peripheral blood and the bone marrow of one patient (LAM) with AIDS and lymphoma. The LCLs from HIV-seropositive patients had phenotypic, cytogenetic, and biological characteristics indistinguishable from those of normal LCLs obtained by infecting B cells with EBV in vitro. The LCLs from LAM patient comprised composite cell populations. Cloning analysis and cell fractionation procedures showed that, beside normal EBV-infected cells, these lines contained a malignant subset population characterized by c-myc rearrangement, abnormal karyotype, and a surface phenotype similar to that of Burkitt's lymphoma cells. Analyses of Ig heavy chain and c-myc oncogene loci showed that these malignant cells were the progeny of a single precursor. Nevertheless, these cells had heterogeneous EBV-fused termini, a finding which indicates that EBV infection followed c-myc rearrangement.
Leukemia 1992
PMID:Characterization of EBV-positive lymphoblastoid cell lines obtained from HIV seropositive patients with or without lymphomas. 131 63

A human leukemia cell line, JK-T1, was established from the bone marrow of a 10-year-old boy with T-cell acute lymphoblastic leukemia. The origin of the leukemic cell line, JK-T1, was demonstrated by its chromosomal and immunologic similarity to the patient's fresh leukemic cells. Karyotypic analysis revealed 46,XY,del(6)(q?),t(8;14)(q24;q13),der(9)t(9;?)(q34;?). In JK-T1, neither rearrangement nor amplification of the c-myc gene was observed apparently because the breakpoint of chromosome 14 was not q11 but q13. JK-T1 was independent of interleukin 2 (IL-2) because of little production of IL-2, little IL-2 receptor (CD25) on the surface, and no response to exogenous IL-2. JK-T1 had lymphocyte function associated antigen-1 (LFA-1) (CD11a, CD18) on its surface and could adhere to the hematologic stromal layer. These characteristics of JK-T1 cell line are considered to be useful not only for evaluating the role of t(8;14) but also in studying the adhesion molecules of leukemia.
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PMID:Establishment and characteristics of a T-cell acute lymphoblastic leukemia cell line, JK-T1, with a chromosomal translocation between 8q24 and 14q13. 133 81

Mouse plasmacytomas induced by pristane oil alone, or in combination with Abelson murine leukemia virus (A-MuLV), regularly carry one of three alternative chromosomal translocations that juxtapose c-myc to immunoglobulin heavy- or light-chain loci. E mu-c-myc transgenic mice develop translocation-free plasmacytomas after induction by pristane oil and/or A-MuLV [Sugiyama, H., Silva, S., Wang, Y., Weber, G., Babonits, M., Rosen, A., Wiener, F. & Klein, G. (1990). Int. J. Cancer, 46, 845-852]. In order to test whether another member of the myc family, N-myc, could play a similar role as c-myc, we treated E mu-N-myc transgenic mice with pristane and helper-free A-MuLV. Of 20 mice that received a single pristane injection followed by A-MuLV, 17 developed plasmacytomas with a mean latency period of 54 +/- 20 days. In a corresponding group that only received a single pristane injection, five out of six transgenic mice developed plasmacytomas with a mean latency period of 142 +/- 32 days. However, after three monthly injections of pristane, all 15 transgenic mice developed plasmacytomas with a mean latency period of 128 +/- 20 days. All plasmacytomas expressed the N-myc transgene, while none of them expressed either c-myc or endogenous N-myc. None of the tumors carried the usual plasmacytoma-associated translocations.
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PMID:Functional homology between N-myc and c-myc in murine plasmacytomagenesis: plasmacytoma development in N-myc transgenic mice. 137 20

The BCR/ABL oncogene in chronic myelogenous leukemia produces an activated tyrosine kinase fusion protein (p210). Like other tyrosine kinase oncogenes, BCR/ABL can abrogate the interleukin-3 (IL-3) dependence of lymphoid cell lines. To investigate the ability of BCR/ABL to generate growth factor independence in myeloid cells, the IL-3 dependent myeloid cell line NFS/N1.H7 (H7) was transfected with the p210BCR/ABL-containing plasmid, pGD210. Stable clones A54 and A74 were capable of IL-3 independent growth and tumor formation in syngeneic mice. Relief of growth factor dependence was not mediated by autocrine release of IL-3. The baseline proliferation rate of the BCR/ABL transformed cells was greater than that of the parental H7 cells maximally stimulated by IL-3. Abundant constitutive expression of c-myc, c-jun, and c-fos was observed in the p210BCR/ABL transfectants even in low serum conditions. In contrast, c-myc expression in H7 cells was dependent upon IL-3 stimulation, and neither c-jun nor c-fos was highly expressed following IL-3 stimulation in H7 cells. Thus, BCR/ABL transformation and relief of IL-3 dependence involve not only pathways that can substitute for IL-3 induced growth via tyrosine kinase mediated signals, but also pathways that recruit constitutive c-jun and c-fos expression.
Leukemia 1992 Aug
PMID:BCR/ABL confers growth factor independence upon a murine myeloid cell line. 137 13

Monoclonal antibodies and flow cytometry were used to detect the expression of c-myc and c-myb in the bone marrow (BM) and peripheral blood (PB) cells of patients with acute myelogenous leukemia (AML). The expression of neither gene was correlated with the percent blast cells in the BM or PB nor was there a correlation between c-myc and c-myb expression. A wide range of expression of each gene was found within each FAB type of AML. Patients who had a high proportion of leukemia cells expressing c-myb were less likely to respond to remission induction therapy than patients in whom a low proportion of cells expressed c-myb. This association appears to reflect an inverse relationship between the proportion of cells expressing c-myb and the sensitivity of leukemia cells to the killing effects of chemotherapy in vivo. Treatment outcome was unrelated to c-myc expression.
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PMID:c-myc and c-myb expression in acute myelogenous leukemia. 140 3

A highly malignant human T-cell receptor (TCR) gamma/delta+ T-cell leukemia was shown to have a productive rearrangement of the TCR delta locus on one chromosome 14 and a novel t(8;14)(q24;q11) rearrangement involving the J delta 1 gene segment on the other chromosome 14. Chromosome walking coupled with pulsed-field gel electrophoretic (PFGE) analysis determined that the TCR J delta 1 gene fragment of the involved chromosome was relocated approximately 280 kb downstream of the c-myc proto-oncogene locus found on chromosome band 8q24. This rearrangement was reminiscent of the Burkitt's lymphoma variants that translocate to a region identified as the pvt-1 locus. Sequence comparison of the breakpoint junctions of interchromosomal rearrangements in T-cell leukemias involving the TCR delta-chain locus revealed novel signal-like sequence motifs, GCAGA(A/T)C and CCCA(C/G)GAC. These sequences were found on chromosome 8 at the 5' flanking site of the breakpoint junction of chromosome 8 in the TCR gamma/delta leukemic cells reported here and also on chromosome 1 in T-cell acute lymphocytic leukemia patients carrying the t(1;14)(p32;q11) rearrangement. These results suggest that (i) during early stages of gamma delta T-cell ontogeny, the region 280 kb 3' of the c-myc proto-oncogene on chromosome 8 is fragile and accessible to the lymphoid recombination machinery and (ii) rearrangements to both 8q24 and 1p32 may be governed by novel sequence motifs and be subject to common enzymatic mechanisms.
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PMID:Molecular involvement of the pvt-1 locus in a gamma/delta T-cell leukemia bearing a variant t(8;14)(q24;q11) translocation. 140 58

The present work has examined the effects of okadaic acid, an inhibitor of type 1 and 2A protein phosphatases, on the regulation of c-jun expression during monocytic differentiation of U-937 leukemia cells. The results demonstrate that okadaic acid treatment is associated with induction of a differentiated monocyte phenotype characterized by: (a) growth arrest; (b) increases in Mac-1 cell surface antigen expression; (c) down-regulation of c-myc transcripts; and (d) induction of tumor necrosis factor gene expression. This induction of monocytic differentiation was associated with transient increases in c-jun mRNA levels, which were maximal at 6 h. Similar effects were obtained for the c-fos gene. Run-on analysis demonstrated detectable levels of c-jun transcription in U-937 cells and that this rate is increased approximately 40-fold following okadaic acid exposure. c-jun mRNA levels were superinduced in cells treated with both okadaic acid and cycloheximide, whereas inhibition of protein synthesis had little, if any, effect on okadaic acid-induced c-jun transcription. The half-life of c-jun mRNA was similar (45-50 min) in both untreated and okadaic acid-induced cells. In contrast, treatment with both okadaic acid and cycloheximide was associated with stabilization (t 1/2 = 90 min) of c-jun transcripts. Taken together, these findings indicate that the induction of c-jun transcription by okadaic acid is controlled primarily by a transcriptional mechanism. Since previous studies have demonstrated that the c-jun gene is autoinduced by Jun/AP-1, we also studied transcription of c-jun promoter (positions -132/+170)-reporter gene constructs with and without a mutated AP-1 element.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of c-jun expression during induction of monocytic differentiation by okadaic acid. 141 3

Murine radiation-induced acute myeloid leukemia (RI-AML) may be considered as the experimental counterpart of human secondary leukemia. Three new myelomonocytic cell lines derived from RI-AML and carrying a partially deleted chromosome 2 are described. The RI-AML cells responded with increased proliferation after being incubated with the hemopoietic growth factors rG-CSF, rGM-CSF and IL-3. Increased proliferation of the same extent without any effect in differentiation, was also demonstrated in the RI-AML cells after incubation with IL-6 and with mouse lung conditioned medium (CM) and Krebs ascites tumor cells CM which induce differentiation in normal and most leukemic myeloid cells. Down-regulation of the c-myc gene and induction of (2'-5') oligo-adenylate synthetase (reflecting autocrine interferon secretion), two essential mechanisms operating during arrest of growth and concomitant differentiation, were demonstrated to be absent in RI-AML cells. In contrast, the M1 cells responded to the above differentiating factors with growth arrest and differentiation and with appropriate c-myc down-regulation and synthetase induction. The genetic basis for the distinct RI-AML cells' behavior may be connected with the loss or structural and/or functional abnormalities of DNA sequences located in the deleted part of chromosome 2 or in the respective allele. The presently described new RI-AML cell lines may be used for studies concerning myeloid leukemogenesis in general and secondary leukemia in particular.
Leukemia 1992 Dec
PMID:Absence of negative growth regulation in three new murine radiation-induced myeloid leukemia cell lines with deletion of chromosome 2. 145 74


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