Emergence of a cell line with extreme hypodiploidy in blast crisis of chronic myelocytic leukemia.
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Cytogenetic studies in a patient with chronic myelocytic leukemia (CML) demonstrated the emergence of an extremely hypodiploid cell line at the time of blast crisis, a modal chromosome number of 35, with the modal karyotype 35,XY, -3, -4, -5, -7, -9, -11, -12, -13, -15, -16, -17, -19, -20, -22, + t(9;22) (q34;q11, + Mar1, + Mar2, + Mar3. Giemsa-banding confirmed complex chromosome rearrangements and demonstrated distinct banding patterns for the marker chromosomes. Cytologic characteristics of the leukemia blasts were predominantly myeloid. There was no important clinical response to chemotherapy, including vincristine and prednisone, or to radiotherapy. (+info)
Nucleotide sequence of a t(14;18) chromosomal breakpoint in follicular lymphoma and demonstration of a breakpoint-cluster region near a transcriptionally active locus on chromosome 18.
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The t(14;18)(q32;21) chromosomal translocation characteristic of follicular lymphomas is the most common cytogenetic abnormality known to be associated with any specific type of hematolymphoid malignancy. A fragment of DNA containing the crossover point between chromosomes 14 and 18 was cloned from the tumor cells of a patient with a follicular lymphoma carrying this translocation. Nucleotide sequence analysis of the breakpoint DNA revealed that the break in chromosome 14 occurred in joining region 4(J4) of the nonfunctional immunoglobulin heavy chain allele. This finding and other structural similarities of the breakpoint with the functional diversity region-joining region (D-J) joint in this lymphoma suggest that D-J recombination enzymes played a role in the mechanism of the t(14;18) translocation. Hybridization analysis of DNA from 40 follicular lymphomas showed that the majority of t(14;18) translocations occur on chromosome 18 DNA within 4.2 kilobases of the cloned breakpoint. A DNA probe from this breakpoint-cluster region detects transcription products in the tumor cells from which it was cloned and in a B-lymphoma cell line containing a t(14;18) translocation. (+info)
Regional localization of human gene loci on chromosome 9: studies of somatic cell hybrids containing human translocations.
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Somatic cell hybrids were derived from the fusion of (1) Chinese hamster cells deficient in hypoxanthine guanine phosphoribosyltransferase (HPRT) and human cells carrying an X/9 translocation and (2) Chinese hamster cells deficient in thymidine kinase (TK) and human cells carrying a 17/9 translocation. Several independent primary hybrid clones from these two series of cell hybrids were analyzed cytogenitically for human chromosome content and electrophoretically for the expression of human markers known to be on human chromosome 9. The results allow the assignment of the loci for the enzymes galactose-1-phosphate uridyltransferase (GALT), soluble aconitase (ACONs), and adenylate kinase-3 (AK3) to the short arm of chromosome 9 (p11 to pter) and the locus for the enzyme adenylate kinase-1 (AK1) to the distal end of the long arm of human chromosome 9 (hand q34). Earlier family studies have shown that the locus for AK1 is closely linked to the ABO blood group locus and to the locus of the nail-patella (Np) syndrome. Thus the regional localization of AK1 locus permits the localization of the AK1-Np-ABO linkage group. (+info)
Regulatory factors specific for adult and embryonic globin genes may govern their expression in erythroleukemia cells.
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In order to test if trans-acting regulatory factors specific for globin genes of the adult and embryonic stages of development exist in erythroid cells, transcriptionally active embryonic and adult globin genes on the same chromosome were transferred by cell fusion from the human leukemia cell K562 into phenotypically adult mouse erythroleukemia cells. Restriction-fragment-length polymorphisms of the K562 zeta (embryonic) globin genes were used to establish that all three copies of human chromosome 16 present in the K562 cell showed the same pattern of human globin gene expression after transfer to the mouse erythroleukemia cell. Adult (alpha) but not embryonic (zeta) human globin mRNA was detected in all nine of the independently derived mouse erythroleukemia hybrid cells, each of which contained human chromosome 16. Restriction endonuclease studies of the K562 alpha- and zeta-globin genes after transfer into the mouse erythroleukemia cell showed no evidence of rearrangements or deletions that could explain this loss of zeta-globin gene expression. These data suggest that regulation of globin gene expression in these erythroleukemia cells involves trans-acting regulatory factors specific for the adult and embryonic stages of development. (+info)
Cloning, sequencing, and chromosomal localization of human term placental alkaline phosphatase cDNA.
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A human term (third trimester) placental alkaline phosphatase (PLAP; EC 3.1.3.1) cDNA was isolated from a human placental lambda gt11 cDNA library. The expression library was screened by using rabbit antibodies against PLAP and oligonucleotide probes. DNA sequence analysis of a positive clone with an insert of 2.7 kilobase pairs allowed us to predict the complete amino acid sequence of PLAP (530 residues), which coincided with the reported 42 N-terminal amino acid sequence of PLAP except at position 3. Contrary to the previous supposition that there was no amino acid sequence homology between PLAP and Escherichia coli alkaline phosphatase (471 residues), we found 30% overall homology, with regions of strong homology including the putative active site and the metal-binding sites. The 44-residue C-terminal extension of PLAP has a stretch of 17 hydrophobic amino acids, which presumably anchors the protein to the plasma membrane, a change perhaps necessary for the transition from a bacterial periplasmic enzyme to a mammalian membrane-associated enzyme. We have also localized PLAP-related DNA sequences mainly on chromosome 2 and to a lesser degree on chromosome 17. It seems likely therefore that the PLAP gene resides on chromosome 2 and other member(s) of the alkaline phosphatase family may exist (on this chromosome and) on chromosome 17. (+info)
The gene for human p53 cellular tumor antigen is located on chromosome 17 short arm (17p13).
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A clone that cross-hybridizes with a mouse p53 probe has been isolated from a cDNA library of simian virus 40-transformed human fibroblasts. This cloned human p53 cDNA was used as a probe to examine DNAs obtained from human-rodent somatic cell hybrids that have segregated human chromosomes. The results show that the human p53 gene is located on chromosome 17. In addition, Southern analysis of hybrids prepared from human cells containing a chromosome 17 translocation allowed regional localization of the human p53 gene to the most distal band on the short arm of this chromosome (17p13). Localization of the p53 gene to 17p13 was confirmed by in situ hybridization of metaphase spreads with the human p53 probe. (+info)
Thymidylate synthase-deficient Chinese hamster cells: a selection system for human chromosome 18 and experimental system for the study of thymidylate synthase regulation and fragile X expression.
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Chinese hamster lung (CHL) V79 cells already deficient in hypoxanthine phosphoribosyltransferase were exposed to uv light and selected for mutations causing deficiency of thymidylate synthase (TS) by their resistance to aminopterin in the presence of thymidine and limiting amounts of methyl tetrahydrofolate. Three of seven colonies chosen for initial study were shown to be thymidylate synthase deficient (TS-) by enzyme assay, thymidine auxotrophy, and their inability to incorporate labeled deoxyuridine into their DNA in vivo. Complementation analysis of human X TS- hamster hybrids revealed that TS activity segregated with human chromosome 18. Southern analysis of a panel of 14 human X hamster hybrids probed with complementary DNA from mouse TS confirmed the chromosome assignment of TS to human chromosome 18; quantitative Southern blotting using unbalanced human cell lines further localized the gene to 18q21.31----qter. Another hybrid was generated that contained a human X chromosome with the Xq28 folate-dependent fragile site as its only human chromosome in a hamster TS- background. The fragile site could be easily and reproducibly expressed in this hybrid without the use of antimetabolites simply by removing exogenous thymidine from the medium. These TS-deficient cells are useful for: somatic cell genetics as a unique selectable marker for human chromosome 18, studies on regulation of the TS gene, and analysis of the fragile (X) chromosome and other folate-dependent fragile sites. (+info)
The nerve growth factor receptor gene is at human chromosome region 17q12-17q22, distal to the chromosome 17 breakpoint in acute leukemias.
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Genomic and cDNA clones for the human nerve growth factor receptor have been used in conjunction with somatic cell hybrid analysis and in situ hybridization to localize the nerve growth factor receptor locus to human chromosome region 17q12-q22. Additionally, part, if not all, of the nerve growth factor receptor locus is present on the translocated portion of 17q (17q21-qter) from a poorly differentiated acute leukemia in which the chromosome 17 breakpoint was indistinguishable cytogenetically from the 17 breakpoint observed in the t(15;17)(q22;q21) translocation associated with acute promyelocytic leukemia. Thus the nerve growth factor receptor locus may be closely distal to the acute promyelocytic leukemia-associated chromosome 17 breakpoint at 17q21. (+info)