Establishment of a new myeloid leukemia cell line (TK-1), and isolation of cells having a translocation involving a band 17q23

The Mayo Clinic Florida Microdosimetric Kinetic Model of Clonogenic Survival: Application to Various Repair-Competent Rodent and Human Cell Lines

The relative biological effectiveness (RBE) calculations used during the planning of ion therapy treatments are generally based on the microdosimetric kinetic model (MKM) and the local effect model (LEM). The Mayo Clinic Florida MKM (MCF MKM) was recently developed to overcome the limitations of previous MKMs in reproducing the biological data and to eliminate the need for ion-exposed in vitro data as input for the model calculations. Since we are considering to implement the MCF MKM in clinic, this article presents (a) an extensive benchmark of the MCF MKM predictions against corresponding in vitro clonogenic survival data for 4 rodent and 10 cell lines exposed to ions from ¹H to ²³⁸U, and (b) a systematic comparison with published results of the latest version of the LEM (LEM IV). Additionally, we introduce a novel approach to derive an approximate value of the MCF MKM model parameters by knowing only the animal species and the mean number of chromosomes. The overall good agreement between MCF MKM predictions and in vitro data suggests the MCF MKM can be reliably used for the RBE calculations. In most cases, a reasonable agreement was found between the MCF MKM and the LEM IV.

Identification and characterization of BPTF, a novel bromodomain transcription factor

The bromodomain is a 110-amino-acid conserved structural region associated with proteins that regulate signal-dependent, nonbasal transcription. The bromodomain can regulate histone acetyl transferase activity and interacts specifically with acetylated lysine residues. A key role for bromodomain proteins in maintaining normal proliferation is indicated by the implication of several bromodomain proteins in cancer, with four of these identified at translocation breakpoints. We searched EST databases for novel bromodomain genes. The sequence from one EST was used to initiate generation of a full-length clone from a testis cDNA library. The completed sequence encodes a predicted protein of 2781 amino acids, which, in addition to the bromodomain, harbors further motifs characteristic of a transcriptional coactivator: two PHD fingers and an extensive glutamine-rich acidic domain. There are several other regions that are conserved with the Caenorhabditis elegans putative protein F26H11, which may be functionally homologous. The novel gene, called BPTF, is expressed in all tissues examined as a 10.5-kb transcript. The protein has extensive identity with the smaller FAC1 protein, suggesting that the two either are derived from the same locus or are synonymous. BPTF has been mapped to 17q23. Functional domains found within BPTF are consistent with a role for this protein in hormonally regulated, chromatin-mediated regulation of transcription.

Interleukins and colony stimulating factors in human myeloid leukemia cell lines

The present review has summarized the expression, production and effects of the human interleukins (IL) 1-11 and myelopoietic colony stimulating factors (CSF) in the established myeloid leukemia cell lines and in cells from patients with acute myeloid leukemia as well as the oncogene expression reported in these myeloid leukemia cell lines. The genetic dissection of leukemic myelopoiesis may provide new perspectives for the control of myeloid leukemias. Based on their expression of phenotypic markers (e.g., surface antigens, cytochemical staining, etc.), myeloid cell lines can be further subdivided into myelogenous, monocytic, erythroid and megakaryoblastic leukemia cell lines. Due to the close relationship of erythroid and megakaryoblastic progenitor cells and to the existence of a probably common precursor cell giving rise to these two different cell lineages, many megakaryoblastic cell lines express erythroid markers (e.g., expression of hemoglobin or glycophorin A) and conversely cell lines with a predominant erythroid profile might display megakaryoblastic features (e.g., platelets peroxidase or glycoproteins CD41, CD42b or CD61). The recent cloning of the specific cytokine: thrombopoietin (TPO) and its receptor generated a strong interest in these particular myeloid cell lines that are discussed in more detail in the present review. Both normal and leukemic megakaryocytopoiesis are stimulated by granulocyte-macrophage colony stimulating factor (GM-CSF), IL-3, GM-CSF/IL-3 fusion protein, IL-6, IL-11 and TPO but inhibited by IL-4, interferon-alpha (IFN-alpha) and IFN-gamma. Human megakaryoblastic leukemia cell lines have common biological features: high expression of the megakaryocytic specific antigen (CD41); high expression of early myeloid antigens (CD34, CD33 and CD13); constitutive expression of IL-6 and platelet-derived growth factor; a complex karyotype picture; expression of c-kit (the stem cell factor receptor); growth-dependency or -stimulation by IL-3 and/or GM-CSF; and in vivo tumorigenicity in mice associated with marked fibrosis. Whereas numerous chemical and biologic agents induce granulocytic and/or monocytic differentiation of myeloid leukemia cell lines, only a few agents including phorbol myristate acetate, vitamin D3, IFN-alpha, IL-6 and thrombin have been reported to induce megakaryocytic differentiation in the megakaryoblastic leukemia cells.

Involvement of c-myc oncogene in lymphoma cell lines with no detectable chromosome rearrangement of band 8q24

Two lymphoma cell lines of B-cell type were established from Japanese patients with diffuse small noncleaved cell lymphoma. Cytogenetic analysis revealed a 14q+ marker chromosome in both cell lines, and a t(8;14)(q24.1;q32.3) seemed most likely to have occurred. The chromosome 8 pair, however, had no abnormalities. Molecular analysis demonstrated c-myc amplification lacking gross rearrangement in one cell line and genetic rearrangement of c-myc at the first intron as well as aberrant sizes of c-myc mRNA in the other cell line. In the latter case, it is possible that a t(8;14)(q24.1;q32.3) was buried in an unrecognized complex translocation. A combination of cytogenetic and molecular studies to determine the precise nature of the 14q32 translocation is discussed.

Phenotypic conversion of T lymphoblastic lymphoma to acute biphenotypic leukemia composed of lymphoblasts and myeloblasts. Molecular genetic evidence of the same clonal origin

Acute biphenotypic leukemia composed of lymphoblasts and myeloblasts developed in a patient with T lymphoblastic lymphoma (T-LBL) who had an anterior mediastinal mass. A novel myeloid cell line, termed TK-1, has been established from his peripheral blood after the leukemic conversion. The identical rearranged pattern of T cell receptor gamma-chain gene was observed among the DNAs derived from lymph node cells in the lymphoma phase, the myeloid cell line TK-1, and the subclones with different karyotypes (TK-1B and TK-1D), which showed that myeloid cells had been derived from the T-LBL of the same patient. This finding demonstrates that phenotypic conversion occurs in the clonally propagating tumor cells and suggests that some hematopoietic cells retain the capacity to adopt either lineage.