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

The role of the X region of the genome of the human T-cell leukemia virus type I (HTLV-I) in the immortalization of lymphocytes has been difficult to distinguish from its role in viral replication as this region encodes at least two genes, tax and rex, required for replication and the expression of viral proteins. To determine whether the X region does encode immortalizing functions, a fragment of the HTLV-I provirus capable of expressing known X-region proteins was inserted into the genome of a transformation-defective, replication-competent Herpesvirus saimiri. Infection of fresh mitogen-activated human cord blood and thymocytes yielded immortal T-cell lines that had the same phenotype (CD4+, CD5+, HLA class II+, interleukin 2 receptor alpha-chain +) as lymphocytes transformed by cocultivation with HTLV-I. These experiments demonstrate that the X region encodes the functions of HTLV-I that immortalize a distinct subpopulation of human T cells. The experiments also demonstrate the utility of the H. saimiri vector for the transduction of heterologous genes into human T cells.
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PMID:Transformation to continuous growth of primary human T lymphocytes by human T-cell leukemia virus type I X-region genes transduced by a Herpesvirus saimiri vector. 254 43

The effects of 1,25(OH)2D3 and dexamethasone on cellular proliferation and gene expression of the HTLV-I-infected T-cell line, KH-2, established from a patient with adult T-cell leukemia, endemic in the south-west Japanese islands and the Caribbean, were examined. KH-2 cells are integrated by HTLV-I proviral DNA and expressed mRNA for c-myc, IL-2 receptor alpha-chain (IL-2R alpha), and T-cell receptor beta-chain (TCR beta) while it did not express IL-2 mRNA. 1,25(OH)2D3 and dexamethasone did not suppress the mRNA levels of HTLV-I, IL-2R alpha or TCR beta but reduced the c-myc mRNA level. The reduction of c-myc mRNA level was marked in 1,25(OH)2D3-treated cells but relatively weak in dexamethasone-treated cells. This inhibitory effect of the steroid hormones correlated with the inhibition of KH-2 cell proliferation.
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PMID:Suppression of c-myc mRNA expression by steroid hormones in HTLV-I-infected T-cell line, KH-2. 279 41

By taking advantage of "chromosomal walking" techniques, we have obtained clones that encompass the T-cell receptor (TCR) delta-chain gene. We analyzed clones spanning the entire J alpha region extending 115 kilobases 5' of the TCR alpha-chain constant region and have shown that the TCR delta-chain gene is located over 80 kilobases 5' of C alpha. TCR delta-chain gene is rearranged in the gamma/delta-expressing T-cell line Peer and is deleted in alpha/beta-expressing T-cell lines. Sequence analysis of portions of this genomic region demonstrates its identity with previously described cDNA clones corresponding to the C delta and J delta segments. Furthermore, we have analyzed a t(8;14)-(q24;q11) chromosome translocation from a T-cell leukemia and have shown that the J delta segment is rearranged in cells deriving from this tumor and probably directly involved in the translocation. Thus, the newly cloned TCR delta chain is implicated in the genesis of chromosome translocations in T-cell malignancies carrying cytogenetic abnormalities of band 14q11.
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PMID:Cloning of the gene encoding the delta subunit of the human T-cell receptor reveals its physical organization within the alpha-subunit locus and its involvement in chromosome translocations in T-cell malignancy. 283 65

Human leukemic T cells carrying a t(10;14)(q24;q11) chromosome translocation were fused with mouse leukemic T cells, and the hybrids were examined for genetic markers of human chromosomes 10 and 14. Hybrids containing the human 10q+ chromosome had the human genes for terminal deoxynucleotidyltransferase that has been mapped at 10q23-q25 and for C alpha [the constant region of TCRA (the alpha-chain locus of the T-cell antigen receptor gene)], but not for V alpha (the variable region of TCRA). Hybrids containing the human 14q- chromosome retained the V alpha genes. Thus the 14q11 breakpoint in the t(10;14) chromosome translocation directly involves TCRA, splitting the locus in a region between the V alpha and the C alpha genes. These results suggest that the translocation of the C alpha locus to a putative cellular protooncogene located proximal to the breakpoint at 10q24, for which we propose the name TCL3, results in its deregulation, leading to T-cell leukemia. Since hybrids with the 10q+ chromosome also retained the human terminal deoxynucleotidyltransferase gene, it is further concluded that the terminal deoxynucleotidyltransferase locus is proximal to the TCL3 gene, at band 10q23-q24.
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PMID:Alpha-chain locus of the T-cell antigen receptor is involved in the t(10;14) chromosome translocation of T-cell acute lymphocytic leukemia. 288 38

Chromosome analysis was performed on 1 patient with diffuse lymphoma of mixed type by histologic diagnosis and on 7 patients with the acute type of adult T-cell leukemia (ATL). Specific abnormalities in chromosome 14 at break band q11 with the assigned locus of the alpha-chain gene of the T-cell antigen receptor were identified in 6 of 8 patients. Inv(14) (q11q32) was found in 2 patients and translocation of chromosome 14 at break band q11 was observed in 4. Donor chromosomes involved in translocation of the 14q11 varied, i.e., chromosomes 3, 7 or X, with the exception of one patient whose donor chromosome origin could not be determined. The breakpoint in chromosome 3 was in band p25, a region reported to include the locus of the c-raf-I oncogene. In chromosome 7, it was in band p11, a region reported to include the locus of the c-erb-B oncogene, and in the sex chromosome X, it was in band q11. One patient also had a chromosome 14 aberration at break band q32. Of the 2 remaining patients, one had lost chromosome 14 and the other had an isochromosome 14q. Our observation and other reported findings suggest that the rearrangement of chromosome 14 at break band q11 is specific for lymphoma-type or acute-type ATL patients, and aberrations of proto-oncogene expression or the coding sequence by recombination involving a T-cell antigen receptor gene due to chromosome inversion or chromosome translocation may play an important role in T-cell neoplasia including ATL.
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PMID:Specific abnormalities of chromosome 14 in patients with acute type of adult T-cell leukemia/lymphoma. 288 76

A B-cell line having translocations of chromosome 14 at break band q11 (the assigned locus of the alpha-chain gene of the T-cell antigen receptor) and chromosome 3 at break band p25 (the assigned locus of the c-raf-1 oncogene) was established from peripheral blood leukocytes of an adult T-cell leukemia (ATL) patient. The same chromosome 14 aberration at break band q11 and chromosome 3 aberration at break band p25 were also found in fresh T-cell leukemia cells. The B-cell line is surface immunoglobulin (sIg)+, immunoglobulin gene rearrangement+, ATL-specific antigen (ATLA)+, HTLV-1 proviral genome+, Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA)+ and the EBV DNA genome+. The fresh T-leukemic cells were T-cell receptor gene rearrangement+, the HTLV-1 proviral genome+ and EBV DNA genome.
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PMID:A B-cell line having chromosome 14 aberration at break band q11 derived from an adult T-cell leukemia patient. 289 57

The surface receptor for immunoglobulin E (IgE) on rat basophilic leukemia cells and their normal counterparts has been postulated to consist of four polypeptide chains: a 45-kDa alpha-chain which binds IgE, a 33-kDa beta-component and two disulfide-linked, 9-10-kDa gamma-polypeptides. The instability of this complex in mild detergents makes it possible that, in vivo also, the structure may not be stable and that there is an independent assembly or exchange of the chains. We studied this question using surface-labeling and biosynthetic labeling techniques and found that the chains turn over coordinately and do not independently exchange. The results provide further support for the proposal that the alpha beta gamma 2 complex is the unit receptor for IgE.
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PMID:Coordinate synthesis and degradation of the alpha-, beta- and gamma-subunits of the receptor for immunoglobulin E. 293 82

The structure and rearrangement of the human T-cell receptor alpha-chain gene have been analysed. The constant region segment is comprised of four exons, with the 3' non-coding region present as a separate exon. Two J alpha segments have been identified by sequence analysis about 4 X 10(3) and 15 X 10(3) base-pairs upstream from the constant region segment. Analysis of alpha-chain rearrangements in a panel of T-cells reveals the presence of at least four more J alpha segments within 19 X 10(3) base-pairs of C alpha and suggests the existence of additional J alpha segments further upstream. This dispersed organization of the J alpha region contrasts with the clustered organization observed in other lymphoid rearranging genes. The use of J alpha probes in diagnostic purposes for T-cell leukaemia is not, therefore, convenient and will require a number of different probes to ensure complete analysis of the locus.
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PMID:Organization of the T-cell receptor alpha-chain gene and rearrangement in human T-cell leukaemias. 301 57

Characterization of tumors that arise spontaneously in the AKR mouse indicates that they are derived from cells of a distinct T-cell lineage. Cells in this subclass bear surface antigens, designated Tpre, Tthy, Tind, and Tsu, which are encoded by genes in the Tsu linkage group on murine chromosome 12. We have examined the rearrangement and expression of genes encoding the T-cell alpha, beta, and gamma chains in these tumors. Although these cells contain alpha-chain mRNA, they do not produce a normal-sized beta-chain mRNA. Most of them also lack gamma-chain mRNA. Each thymic leukemia was derived from a cell arrested at a different stage of development as defined by their expression of terminal deoxynucleotidyl transferase and Thy-1 mRNA. The data presented here are consistent with a model in which thymocytes expressing Tpre, Tthy, Tind, or Tsu undergo somatic development parallel to the development of other T cells. However, these thymocytes do not appear to differentiate into cells bearing alpha-beta heterodimers of the T-cell antigen receptor.
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PMID:AKR murine thymic leukemias are from a distinct thymic cell lineage and do not express the beta chain of the T-cell antigen receptor. 309 8

T-cell tumors are characterized by inversions or translocations of chromosome 14. The breakpoints of these karyotypic abnormalities occur in chromosome bands 14q11 and 14q32--the same bands in which the T-cell receptor (TCR) alpha-chain and immunoglobulin heavy chain genes have been mapped, respectively. Patients with ataxia-telangiectasia are particularly prone to development of T-cell chronic lymphocytic leukemia with such chromosomal abnormalities. We now describe DNA rearrangements of the TCR alpha-chain gene in an ataxia-telangiectasia-associated leukemia containing both a normal and an inverted chromosome 14. The normal chromosome 14 has undergone a productive join of TCR alpha-chain variable (V alpha) and joining (J alpha) gene segments. The other allele of the TCR alpha-chain gene features a DNA rearrangement, about 50 kilobases from the TCR alpha-chain constant (C alpha) gene, that represents the breakpoint of the chromosome 14 inversion; this breakpoint is comprised of a TCR J alpha segment (from 14q11) fused to sequences derived from 14q32 but on the centromeric side of C mu. These results imply that 14q32 sequences located at an undetermined distance downstream of the immunoglobulin C mu locus can contribute to the development of T-cell tumors.
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PMID:The breakpoint of an inversion of chromosome 14 in a T-cell leukemia: sequences downstream of the immunoglobulin heavy chain locus are implicated in tumorigenesis. 312 10


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