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

To clarify whether the expression of the WT1 gene in leukemic cells is aberrant or merely reflects that in normal counterparts, the expression levels of the WT1 gene were quantitated for normal hematopoietic progenitor cells. Bone marrow (BM) and umbilical cord blood (CB) cells were fluorescence-activated cell sorting (FACS)-sorted into CD34+ and CD34- cell populations, and the CD34+ cells into nine subsets (CD34+ CD33-, CD34+ CD33+, CD34+ CD38-, CD34+ CD38+, CD34+ HLA-DR-, CD34+ HLA-DR+, CD34+ c-kit(high), CD34+ c-kit(low), and CD34+ c-kit-) according to the expression levels of CD34, CD33, CD38, HLA-DR, and c-kit. Moreover, acute myeloid leukemic cells were also FACS-sorted into four populations (CD34+ CD33-, CD34+ CD33+, CD34- CD33+, and CD34- CD33-). FACS-sorted normal hematopoietic progenitor and leukemic cells and FACS-unsorted leukemic cells were examined for the WT1 expression by quantitative reverse transcriptase-polymerase chain reaction. The WT1 expression in the CD34+ and CD34- cell populations and in the nine CD34+ subsets of BM and CB was at either very low (1.0 to 2.4 x 10(-2)) or undetectable (< 10(-2)) levels (the WT1 expression level of K562 cells was defined as 1.0), whereas the average levels of WT1 expression in FACS-sorted and -unsorted leukemic cells were 2.4 to 9.3 x 10(-1). Thus, the WT1 expression levels in normal hematopoietic progenitor cells were at least 10 times less than those in leukemic cells. Therefore, we could not find any normal counterparts of BM or CB that expressed the WT1 at levels comparable with those in leukemic cells. These results indicate an aberrant overexpression of the WT1 gene in leukemic cells and imply the involvement of this gene in human leukemogenesis.
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PMID:Aberrant overexpression of the Wilms tumor gene (WT1) in human leukemia. 902 64

It has been supposed in de novo AML that malignant transformation occurs at the level of committed progenitors. Recent data of our group and others provide evidence that in AML malignant transformation may regularly occur at the level of stem cells. These cells can be discriminated by function and specific surface molecules. CD34, a glycophosphoprotein, is a cellular surface antigen characteristically expressed by stem cells. CD34+ stem cells can be further subdivided by the expression of additional surface molecules like CD38 and CD117. In this article we present results from cytogenetic examinations of FACS-isolated stem cell subpopulations in eight patients (four AML and four MDS). Six of them displayed clonal karyotype abnormalities at the time of first diagnoses in the native bone marrow (5q-; 5q- and complex abnormalities; +8; inv(16) and +8; i(17q) and -21; i(21q)). We used CD117, the receptor for the stem cell factor (also KIT oncogene) as a new cellular surface marker. CD34+/CD117+/- stem cell subpopulations were examined in two patients with AML and three patients with MDS. We found leukemic stem cells in every type of stem cell subpopulation examined (CD34+/CD38-, CD34+/CD38+, CD34+/CD117-, CD34+/CD117+). Secondary, progression-associated chromosome abnormalities likewise were demonstrable in CD34+ cells. In three patients a mosaic of normal and abnormal metaphases was found in the highly purified stem cell subpopulations. We conclude that in AML and MDS stem cells are the target of leukemogenic genetic defects. CD117 as a new marker to isolate different CD34+ subpopulations was not sufficient to discriminate between normal and leukemic stem cells. Our findings have implications for autologous stem cell transplantation, high-dose chemotherapy and the pathogenetic concept of leukemogenesis.
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PMID:Cytogenetic analysis of CD34+ subpopulations in AML and MDS characterized by the expression of CD38 and CD117. 918 Feb 91

Acute lymphoblastic leukemia (ALL), the most common cancer in childhood, is characterized by clonal proliferation of transformed lymphoblasts that comprise the majority of marrow and/or blood specimens. Although the leukemic cells typically express antigens associated with lymphoid maturation or activation (ie CD19, CD38, etc), it has been suggested that ALL blasts may evolve from a more primitive precursor. Increased understanding of the phenotypic and molecular heterogeneity of cells in ALL may provide clues to leukemogenesis and/ or impact prognostication or treatment. We utilized a phenotype/genotype approach to measure the prevalence and frequency of cytogenetically aberrant cells in a phenotypically defined primitive compartment (CD34+33-19-38-; CD34+Lin-). Bone marrow cells were flow cytometrically sorted into CD34-Lin+, CD34+Lin+ and CD34+Lin- subpopulations. Fluorescence in situ hybridization (FISH) was used to quantify the frequency of cells with aneusomies in the sorted populations. Approximately 26% (5/19) of ALL cases at diagnosis contain cytogenetically aberrant CD34+Lin- cells. The frequency of cytogenetically aberrant cells in the CD34+Lin- compartment is independent of FAB, WBC and blast counts. These data indicate that cytogenetically aberrant cells may reside in a phenotypically defined primitive subpopulation and suggest that ALL blasts in some patients may evolve from a precursor compartment.
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PMID:Cytogenetically aberrant cells are present in the CD34+CD33-38-19- marrow compartment in children with acute lymphoblastic leukemia. 930 6

A new cell line with megakaryoblastic features, designated UoC-M1, was established from the malignant cells of a 68-year-old patient with acute myeloid leukemia. The patient's leukemic cells reacted with alpha-naphthyl acetate esterase and acid phosphatase and expressed CD7, CD24, CD34, CD38, CD45, HLA-DR and CD61. Cytogenetic analysis of the patient's malignant cells (and of the UoC-M1 cells) showed a human, male hypodiploid karyotype with many chromosome rearrangements and marker chromosomes. Spectral karyotyping (SKY) analysis complemented the G-banded karyotyping and clarified several chromosomal translocations and identified the marker chromosomes. Fluorescence in situ hybridization (FISH) and SKY analysis demonstrated that one marker chromosome contained three segments of chromosome 9 interspersed with three segments of chromosome 11, as well as a portion of chromosome 19. FISH analysis with a probe for MLL revealed that the UoC-M1 cells contained four copies of the MLL gene. Southern blot analysis determined that the MLL gene had a germline profile while Northern and Western analyses showed that the MLL mRNAs and protein were of the appropriate sizes. This is the first report of amplification of the MLL gene which may be an additional mechanism of leukemogenesis or disease progression.
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PMID:Establishment and characterization of a megakaryoblast cell line with amplification of MLL. 966 99

Molecular and cellular markers associated with malignant disease are frequently identified in healthy individuals. The relationship between these markers and clinical disease is not clear, except where a neoplastic cell population can be identified as in myeloma/monoclonal gammopathies of undetermined significance (MGUS). We have used the distinctive phenotype of chronic lymphocytic leukemia (CLL) cells to determine whether low levels of these cells can be identified in individuals with normal complete blood counts. CLL cells were identified by 4-color flow cytometric analysis of CD19/CD5/CD79b/CD20 expression in 910 outpatients over 40 years old. These outpatients were age- and sex-matched to the general population with normal hematologic parameters and no evident history of malignant disease. CLL phenotype cells were detectable in 3.5% of individuals at low level (median, 0.013; range, 0.002- 1.458 x 10(9) cells/L), and represented a minority of B lymphocytes (median, 11%; range, 3%-95%). Monoclonality was demonstrated by immunoglobulin light-chain restriction in all cases with CLL phenotype cells present and confirmed in a subset of cases by consensus-primer IgH-polymerase chain reaction. As in clinical disease, CLL phenotype cells were detected with a higher frequency in men (male-to-female ratio, 1.9:1) and elderly individuals (2.1% of 40- to 59-year-olds versus 5.0% of 60- to 89-year-olds, P =.01). The neoplastic cells were identical to good-prognosis CLL, being CD5+23+20(wk)79b(wk)11a(-)22(wk)sIg(wk)CD38-, and where assessed had a high degree (4.8%-6.6%) of IgH somatic hypermutation. The monoclonal CLL phenotype cells present in otherwise healthy individuals may represent a very early stage of indolent CLL and should be useful in elucidating the mechanisms of leukemogenesis.
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PMID:Monoclonal B lymphocytes with the characteristics of "indolent" chronic lymphocytic leukemia are present in 3.5% of adults with normal blood counts. 1209 58

Ahi-1/AHI-1 (Abelson helper integration site-1) encodes a family of protein isoforms containing one Src homology 3 (SH3) domain and multiple tryptophan-aspartic acid 40 (WD40)-repeat domains. The function of these proteins is unknown, but involvement in leukemogenesis has been suggested by the high frequency of Ahi-1 mutations seen in certain virus-induced murine leukemias. Here we show that in both mice and humans, Ahi-1/AHI-1 expression is highest in the most primitive hematopoietic cells with specific patterns of down-regulation in different lineages. Cells from patients with chronic myeloid leukemia (CML; n = 28) show elevated AHI-1 transcripts in all disease phases and, in chronic phase, in the leukemic cells at all stages of differentiation, including quiescent (G(0)) CD34(+) cells as well as terminally differentiating cells. In the most primitive lin(-)CD34(+)CD38(-) CML cells, transcripts for the 2 shorter isoforms of AHI-1 are also increased. Although 15 of 16 human lymphoid and myeloid leukemic cell lines showed aberrant control of AHI-1 expression, this was not seen in blasts obtained directly from patients with acute Philadelphia chromosome-negative (Ph(-)) leukemia (n = 15). Taken together, our results suggest that down-regulation of AHI-1 expression is an important conserved step in primitive normal hematopoietic cell differentiation and that perturbations in AHI-1 expression may contribute to the development of specific types of human leukemia.
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PMID:Deregulated expression in Ph+ human leukemias of AHI-1, a gene activated by insertional mutagenesis in mouse models of leukemia. 1475 29

The human CD34(+)/CD38(-)/Lin(-) cell subset, comprising approximately 1-10% of the CD34(+) cell population, contains few of the less primitive hematopoietic (lineage-committed) progenitor cells (HPCs) but most of the primitive in vivo engrafting (lympho-)hematopoietic stem cells (HSCs). We analyzed gene expression in CD34(+)/CD38(-)/Lin(-) cell populations isolated from normal human adult donor bone marrow, neonatal placental/umbilical cord blood, and mobilized adult donor peripheral blood stem-progenitor cells. As measured by Affymetrix microarrays, 4746 genes were expressed in CD34(+)/CD38(-)/Lin(-) cells from all three tissues. We also determined the transcriptomes of the stem cell-depleted, HPC-enriched CD34(+)/[CD38/Lin](++) cell population from each tissue. Comparison of CD34(+)/CD38(-)/Lin(-) (HSC-enriched) versus CD34(+)/[CD38/Lin](++) (HPC-enriched, HSC-depleted) cells from each tissue yielded 81 genes overrepresented and 90 genes underrepresented, common to all three of the CD34(+)/CD38(-)/Lin(-) cell populations. These transcripts, which are selectively expressed in HSCs from all three tissues, include a number of known genes (e.g., transcription factors, receptors, and signaling molecules) that might play roles in key functions (e.g., survival, self-renewal, differentiation, and/or migration/adhesion) of human HSCs. Many genes/transcripts of unknown function were also detected by microarray analysis. Serial analysis of gene expression of the bone marrow HSC and HPC populations confirmed expression of most of the overrepresented transcripts for which reliable serial analysis of gene expression tags were detected and additionally suggested that current microarrays do not detect as many as 30% of the transcripts expressed in HSCs, including a number of previously unknown transcripts. This work is a step toward full definition of the transcriptome of normal human HSCs and may identify new genes involved in leukemogenesis and cancer stem cells.
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PMID:Microarray and serial analysis of gene expression analyses identify known and novel transcripts overexpressed in hematopoietic stem cells. 1523 52

The Wilms' tumor gene (WT1) is a transcription factor involved in tumorigenesis, especially in leukemogenesis. However, the role of WT1 expression in nonmalignant hematopoietic cells remains unclear. Furthermore, due to alternative splicing at two sites: 17 amino acid residues of exon 5 (+17AA) and 3 amino acid residues (+KTS) between exons 9 and 10, WT1 gene has four main isoforms (17AA+/KTS+, 17AA+/KTS-, 17AA-/KTS+, 17AA-/KTS-, abbreviation: +/+, +/-, -/+, -/-). The isoforms probably existed in hematopoietic cells, which make the research more complex. The aim of study was to elucidate the expression and its isoforms of WT1 gene in different cell subsets of healthy bone marrow donors. The fluorescence RT-PCR detection system was established to measure the expressions of full-length WT1, WT1 (+17AA) and WT1 (+KTS) in CD34(+)CD38(-) (stem cell), CD34(+)CD38(+) (progenitor cell), CD15(+)CD11b(+) (granulocyte), CD33(+)CD14(+) (monocyte), CD20(+)CD5(-) (B-lymphocyte) and CD20(-)CD5(+) (T-lymphocyte) subsets from 18 normal human bone marrow samples. The results showed that WT1 expressed in CD34(+)CD38(-), CD34(+)CD38(+), CD15(+)CD11b(+) and CD33(+)CD14(+), but not in CD20(+)CD5(-) and CD20(-)CD5(+) subsets. The highest expression was in CD34(+)CD38(-), but decreased gradually in CD15(+)CD11b(+) and CD33(+)CD14(+) subsets. WT1 (+17AA), WT1 (+KTS) and WT1 (+/+) isoforms were predominant in CD34(+)CD38(-) and CD34(+)CD38(+) primitive subsets, while in CD15(+)CD11b(+) and CD33(+)CD14(+) the dominant isoforms were WT1 (-17AA), WT1 (-KTS) and WT1 (-/-). It is concluded that the expression of WT1 in normal bone marrow decreases gradually with cell differentiation. Hematopoietic cells may adjust the ratios of WT1 isoforms to inhibit or promote cell differentiation.
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PMID:[WT1 gene expression and its isoform ratio in different cell subsets of normal human bone marrow]. 1760 75

Receptor or nonreceptor tyrosine kinases (TKs) are known to play an important role in leukemogenesis. Here we studied the level of protein tyrosine phosphorylations in a series of fresh AML samples and evaluated the effect of TK inhibitors. Compared with normal hematopoietic progenitors, a high level of tyrosine phosphorylation was detected in most acute myeloid leukemia (AML) samples. The Src family kinases (SFKs) appeared constitutively activated in most cases, including in the CD34(+)CD38(-)CD123(+) compartment as revealed by the level of phosphorylated tyrosine 416. Lyn was the major SFK family member expressed in an active form in AML cells where it was abnormally distributed throughout the plasma membrane and the cytosol as opposed to normal hematopoietic progenitors. The SFK inhibitor, PP2, strongly reduced the global level of tyrosine phosphorylations, inhibited cell proliferation, and induced apoptosis in patient samples without affecting normal granulomonocytic colony forming units. Moreover, silencing Lyn expression by small interfering RNA in primary AML cells strongly inhibited proliferation. Interestingly, a link between Lyn and the mTOR pathway was observed as PP2 and a Lyn knockdown both affected the phosphorylation of mTOR targets without inhibiting Akt phosphorylation. Lyn should be considered as a novel pharmacologic target for AML therapy.
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PMID:A critical role for Lyn in acute myeloid leukemia. 1805 83

Biased IgHV gene usage in chronic lymphocytic leukemia (CLL) is well documented and suggests antigen involvement in leukemogenesis. IgHV1-69 is one of the most frequently rearranged IgHV genes in CLL and the majority of IgHV1-69 cases lack somatic hypermutation and display poor prognosis. However, its independent prognostic impact remains uncertain given reports showing a low proportion of mutated IgHV1-69 cases and stereotyped IgHV1-69 subsets with divergent clinical outcome. We assessed the frequency and clinical significance of IgHV1-69 gene usage in a cohort of 330 CLL patients. Functional IgHV1-69 gene rearrangements were detected in 32 cases (9.7%), 31 of which were characterised further. Seven (22.6%) were found to have undergone somatic hypermutation. This subgroup had shorter and more diverse complementarity determining region 3 (CDR3) sequences compared with unmutated IgHV1-69 cases. In addition, mutated IgHV1-69 gene status was associated with lower cell surface CD38 expression and less progressive disease as monitored by Binet staging, lymphocyte doubling time and requirement of chemotherapeutic intervention. To conclude, we present data confirming that IgHV1-69 gene rearrangements in CLL are not exclusively associated with unmutated IgHV status. In addition, we show that a somatically hypermutated subgroup may demonstrate more indolent characteristics despite the general association of IgHV1-69 gene usage with aggressive disease.
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PMID:Mutated IgHV1-69 gene usage represents a distinct subgroup associated with indolent disease in chronic lymphocytic leukemia. 1839 27


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