Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0598766 (leukemogenesis)
 4,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By inducing mouse thymomas with carcinogens and gamma-radiation, we have studied the potential of tumor DNA to induce foci in rodent fibroblasts. A high percentage of the tumors used transformed the cultured cells, and the oncogenic phenotype segregated with extra copies of the c-ras gene family. There appears to be selectivity in the activated gene because so far all analyzed tumors induced by carcinogen have activated the N-ras gene, and those induced by radiation have activated the K-ras gene. The K-ras gene is the cellular counterpart of the viral ras oncogene in Kirsten murine sarcoma virus, but the N-ras has not yet been found in a retrovirus. The transformed cells have a marked increase in expression of the oncogene at the RNA and protein level. This model system might be a powerful tool in the study of leukemogenesis.
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PMID:A molecular approach to leukemogenesis: mouse lymphomas contain an activated c-ras oncogene. 658 76

Qa2+ tumor cell lines were previously isolated from individual BALB/cBy (Qa2-) splenic lymphomas induced by murine sarcoma virus-murine leukemia virus-Moloney (MSV-MuLV-M). Two clonally derived cell lines, ORA I-a and Thorbly, and one noncloned cell line, BOMS, expressed Qa2, but neither Ly-1 nor Ly-2 were detected. In order to determine whether eight cloned and two noncloned tumor cell lines all represented a unique population of transformed cells, the presence of a series of surface differentiation antigens as studied. In addition to Qa2, each cell line examined expressed IAd, IEd, H-2Kd, H-2Dd, and receptors for C3b and the Fc portion of immunoglobulin (Ig). Neither Thy-1.2 nor Ig were detected on the cell surfaces, and cytoplasmic Ig was not precipitated from metabolically radiolabeled and detergent-solubilized cell extracts. However, monocyte specific alpha-napththyl acetate esterase-containing granules were present in all cell lines examined. Therefore, a unique Qa2+ monocytic cell is repeatedly isolated after chronic MSV-MuLV-M infection. Further analysis of these cells may provide insight into both the regulation of Qa2 expression and the interactions between monocytes and lymphocytes during leukemogenesis.
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PMID:Repeated isolation of unique Qa2+ Ia+ clonally derived cell lines from Qa2- mice. 697 71

A unique mRNA produced by the t(15;17) (q22-24;q11-21) translocation in the leukemic cells of acute promyelocytic leukemia patients encodes a chimeric protein, PML/RARalpha, which is formed by the fusion of the retinoic acid receptor alpha (RARalpha) and the promyelocytic locus gene (PML). This translocation is often the only visible karyotypic aberration present which is detected in almost 100% of acute promyelocytic leukemia patients. As an initial step to study the role of PML/RARalpha in leukemogenesis, we attempted to express the fusion protein in hematopoietic cells through retrovirus-mediated gene transfer of the retroviral vector, pGPRCHT, which contains the PML/RARalpha cDNA. Transduction of the PML/RARalpha cDNA fragment used in this vector, which extends from the position 31 bp to the position 2638 bp in a transcription unit driven by the Moloney murine sarcoma virus LTR, was found to abrogate the growth factor dependence of TF-1 cells. In addition, introduction of PML/RARalpha into TF-1 cells can protect these cells from the apoptosis usually induced in TF-1 cells by growth factor withdrawal, as measured by three assays for apoptosis: morphology, DNA ladder formation, and end labeling of nicked DNA with fluorescent-conjugated nucleotide precursors followed by a fluorescence-activated cell sorting assay. These data suggest that the PML/RARalpha fusion protein may inhibit programmed cell death in myeloid cells.
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PMID:PML/RARalpha, a fusion protein in acute promyelocytic leukemia, prevents growth factor withdrawal-induced apoptosis in TF-1 cells. 981 19

TEL is a gene frequently involved in specific chromosomal translocations in human leukemia and sarcoma that encodes a member of the ETS family of transcriptional regulators. TEL is unusual among other ETS proteins by its ability to self-associate in vivo, a property that is essential to the oncogenic activation of TEL-derived fusion proteins. We show here that TEL is a sequence-specific transcriptional repressor of ETS-binding site-driven transcription of model and natural promoters. Deletion of the oligomerization domain of TEL or its substitution by the homologous region of monomeric ETS1 impaired the ability of TEL to repress. In contrast, substitution of the oligomerization domain of TEL by unrelated oligomerization domains resulted in an active repressor, showing that the ability of TEL to repress depends on its ability to self-associate. The study of the properties of TEL fusions to the heterologous DNA binding domain of Gal4 identified two autonomous repression domains in TEL, distinct from its oligomerization domain, that are essential to the ability of TEL to repress ETS-binding site-containing promoters. These results have implications for the normal function of TEL, its relation to other ETS proteins, and its role in leukemogenesis.
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PMID:TEL is a sequence-specific transcriptional repressor. 1051 2

The Tel gene (or ETV6) is the target of the translocation (12;22)(p13;q11) in myeloid leukemia. TEL is a member of the ETS family of transcription factors and contains the pointed protein interaction (PNT) domain and an ETS DNA binding domain (DBD). By contrast to other chimeric proteins that contain TEL's PNT domain, such as TEL-platelet-derived growth factor beta receptor in t(5;12)(q33;p13), MN1-TEL contains the DBD of TEL. The N-terminal MN1 moiety is rich in proline residues and contains two polyglutamine stretches, suggesting that MN1-TEL may act as a deregulated transcription factor. We now show that MN1-TEL type I, unlike TEL and MN1, transforms NIH 3T3 cells. The transforming potential depends on both N-terminal MN1 sequences and a functional TEL DBD. Furthermore, we demonstrate that MN1 has transcription activity and that MN1-TEL acts as a chimeric transcription factor on the Moloney sarcoma virus long terminal repeat and a synthetic promoter containing TEL binding sites. The transactivating capacity of MN1-TEL depended on both the DBD of TEL and sequences in MN1. MN1-TEL contributes to leukemogenesis by a mechanism distinct from that of other chimeric proteins containing TEL.
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PMID:The MN1-TEL fusion protein, encoded by the translocation (12;22)(p13;q11) in myeloid leukemia, is a transcription factor with transforming activity. 1109 79

Bone marrow stromal cells constitute a heterogeneous population, and in the present study we investigated intercellular crosstalk via release of soluble mediators between native human AML blasts and fibroblasts/osteoblasts. Coculture of nonleukemic stromal cells and AML blasts separated by a semipermeable membrane decreased proliferation of the fibroblast line HFL1, and the inhibition was maintained when HFL1 and AML cells were cultured in direct contact. A similar inhibitory effect was observed for osteoblastic sarcoma cell lines (Cal72, SJSA-1) and normal osteoblasts. GM-CSF was released by both nonleukemic cells and a subset of AML blast populations, and increased levels of GM-CSF were detected in AML cocultures with fibroblasts and osteoblastic sarcoma cells when testing AML cell populations with constitutive GM-CSF release. Furthermore, constitutive IL-1beta secretion by AML blasts was detected only for a subset of patients, whereas relatively high levels of IL-1RA were observed for all patients; coculture of AML blasts with HFL1 fibroblasts and osteoblastic sarcoma cells increased IL-1beta levels for patients with constitutive IL-1beta secretion, whereas IL-1RA levels were slightly decreased but still generally higher than IL-1beta levels (tested only for HFL1 fibroblasts). The bidirectional crosstalk between AML blasts and stromal cells with increased release of AML growth factors may be important in leukemogenesis, whereas the decreased stromal cell proliferation combined with the persistent release of IL-1RA may in addition inhibit remaining normal hematopoiesis and thereby contribute to bone marrow failure in AML.
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PMID:In vitro effects of native human acute myelogenous leukemia blasts on fibroblasts and osteoblasts. 1530 Jul 97

A 17-year-old boy developed therapy-related acute myeloid leukemia (t-AML) 3 years after the cessation of chemo- and radiotherapy for undifferentiated sarcoma of the liver. At the onset of the t-AML, his white blood cell count was 900/microL with a 46,XY,t(2;3)(p21;q26),del(5)(q?) karyotype. Despite intensive chemotherapy and two hematopoietic stem cell transplants, he died of the leukemia. At the terminal phase, his white blood cell count surpassed 30,000/microL and the Philadelphia (Ph) chromosome appeared. Expression of EVI1 in bone marrow cells was remarkably high at the onset of t-AML, although it was not detected at the end of therapy for the sarcoma. Polymerase chain reaction analysis of bone marrow cells revealed that mRNA for the bcr-abl chimera was negative at the onset of t-AML and positive at the terminal phase. These results suggest that EVI1 overexpression was the major factor contributing to leukemogenesis, and the late appearance of the Ph chromosome is closely associated with the progression to an aggressive form of leukemia.
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PMID:Late appearance of a Philadelphia chromosome in a patient with therapy-related acute myeloid leukemia and high expression of EVI1. 1820 36

We previously reported the development of a lethal myeloid sarcoma in a non-human primate model utilizing retroviral vectors to genetically modify hematopoietic stem and progenitor cells. This leukemia was characterized by insertion of the vector provirus into the BCL2A1 gene, with resultant BCL2A1 over-expression. There is little information on the role of this anti-apoptotic member of the BCL2 family in hematopoiesis or leukemia induction. Therefore we studied the impact of Bcl2a1a lentiviral over-expression on murine hematopoietic stem and progenitor cells. We demonstrated the anti-apoptotic function of this protein in hematopoietic cells, but did not detect any impact of Bcl2a1a on in vitro cell growth or cell cycle kinetics. In vivo, we showed a higher propensity of HSCs over-expressing Bcl2a1a to engraft and contribute to hematopoiesis. Mice over-expressing Bcl2a1a in the hematologic compartment eventually developed an aggressive malignant disease characterized as a leukemia/lymphoma of B-cell origin. Secondary transplants carried out to investigate the primitive origin of the disease revealed the leukemia was transplantable. Thus, Bcl2a1 should be considered as a proto-oncogene with a potential role in both lymphoid and myeloid leukemogenesis, and a concerning site for insertional activation by integrating retroviral vectors utilized in hematopoietic stem cell gene therapy.
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PMID:BCL2A1a over-expression in murine hematopoietic stem and progenitor cells decreases apoptosis and results in hematopoietic transformation. 2311 66

Acute lymphoblastic leukemia in infants represents an aggressive malignancy associated with a high incidence (approx. 80%) of translocations involving the Mixed Lineage Leukemia (MLL) gene. Attempts to mimic Mixed Lineage Leukemia fusion driven leukemogenesis in mice raised the question whether these fusion proteins require secondary hits. RAS mutations are suggested as candidates. Earlier results on the incidence of RAS mutations in Mixed Lineage Leukemia-rearranged acute lymphoblastic leukemia are inconclusive. Therefore, we studied frequencies and relation with clinical parameters of RAS mutations in a large cohort of infant acute lymphoblastic leukemia patients. Using conventional sequencing analysis, we screened neuroblastoma RAS viral (v-ras) oncogene homolog gene (NRAS), v-Ki-ras Kirsten rat sarcoma viral oncogene homolog gene (KRAS), and v-raf murine sarcoma viral oncogene homolog B1 gene (BRAF) for mutations in a large cohort (n=109) of infant acute lymphoblastic leukemia patients and studied the mutations in relation to several clinical parameters, and in relation to Homeobox gene A9 expression and the presence of ALL1 fused gene 4-Mixed Lineage Leukemia (AF4-MLL). Mutations were detected in approximately 14% of all cases, with a higher frequency of approximately 24% in t(4;11)-positive patients (P=0.04). Furthermore, we identified RAS mutations as an independent predictor (P=0.019) for poor outcome in Mixed Lineage Leukemia-rearranged infant acute lymphoblastic leukemia, with a hazard ratio of 3.194 (95% confidence interval (CI):1.211-8.429). Also, RAS-mutated infants have higher white blood cell counts at diagnosis (P=0.013), and are more resistant to glucocorticoids in vitro (P<0.05). Finally, we demonstrate that RAS mutations, and not the lack of Homeobox gene A9 expression nor the expression of AF4-MLL are associated with poor outcome in t(4;11)-rearranged infants. We conclude that the presence of RAS mutations in Mixed Lineage Leukemia-rearranged infant acute lymphoblastic leukemia is an independent predictor for a poor outcome. Therefore, future risk-stratification based on abnormal RAS-pathway activation and RAS-pathway inhibition could be beneficial in RAS-mutated infant acute lymphoblastic leukemia patients.
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PMID:Frequencies and prognostic impact of RAS mutations in MLL-rearranged acute lymphoblastic leukemia in infants. 2340 19

Oncogenic N-/KRAS mutations were frequently associated with MLL/AF10 in acute myeloid leukemia with myeloid sarcoma (MS). To study the cooperating leukemogenesis by MLL/AF10 and KRAS mutation, we retrovirally transduced MLL/AF10(OM-LZ) and KRASG12C into mouse bone marrow cells and generated two immortalized cell lines. The cells carrying cooperating MLL/AF10(OM-LZ) and KRASG12C had immature myelomonocytic phenotypes. Compared to a previously established cell line carrying MLL/AF10(OM-LZ) alone, cooperation of MLL/AF10(OM-LZ) with KRASG12C blocked the cells at a more immature myelomonocytic stage with reduced expression of monocyte/macrophage markers. The mice transplanted with the cells carrying cooperating MLL/AF10(OM-LZ) and KRASG12C, liked those transplanted with the cells carrying MLL/AF10(OM-LZ) alone, induced myeloproliferative disease-like myeloid leukemia, but in a shorter latency and formed multiple MS at the adipose tissues of skin, peritoneum and intraperitoneal cavity. Cooperation of MLL/AF10(OM-LZ) with KRASG12C increased cell adhesion via upregulation of an adhesion G-protein-coupled receptor Gpr125. Knockdown of Gpr125 in the cells by short hairpin RNA reduced cell aggregation and diminished MS formation in the transplanted mice. Our results indicated that upregulation of Gpr125 by cooperating MLL/AF10(OM-LZ) and KRASG12C promoted cell adhesion and contributed to the MS formation.
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PMID:Involvement of Gpr125 in the myeloid sarcoma formation induced by cooperating MLL/AF10(OM-LZ) and oncogenic KRAS in a mouse bone marrow transplantation model. 2356 51


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