Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Wilms' tumor (WT) is a pediatric malignancy that occurs in embryonic kidney. Recently, a putative Wilms' tumor gene (WT1), located on chromosome 11p13, was isolated and characterized. We found constitutive expression of WT1 mRNA in eight out of 22 hematopoietic cell lines and seven out of 26 clinical samples which were derived from patients with various types of hematologic malignancies. WT1 mRNA was detected in four out of six myeloid cell lines, four out of 10 cases of acute myelocytic leukemia, three out of 15 lymphoid cell lines, one out of nine cases of lymphoid malignancies, and one out of six cases of chronic myelocytic leukemia in accelerated phase and blast crisis. One unclassified hematopoietic cell line and a case of myelodysplastic syndrome also expressed WT1 mRNA. No mutations were detectable in the cell lines by Southern blot analysis and a polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis in the four zinc finger domains of the WT1 gene. These results suggest that WT1 gene is expressed in several types of immature lymphoid or myeloid leukemia cells possibly without alterations of the WT1 gene.
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PMID:Expression of the candidate Wilm's tumor gene, WT1, in human leukemia cells. 832 Oct 47

To determine if mutations of the Wilms' tumor predisposing gene (WT1) are associated with haematological malignancies, we have investigated 65 cases of acute leukaemia, including 39 patients in blast crisis of chronic myeloid leukaemia (CML), by amplification of WT1 exons 7, 8 and 9 followed by single-strand conformation polymorphism analysis. WT1 transcripts were detected by RT-PCR in all samples. An exon 7 silent polymorphism (A-->G; Arg 313) was identified in 17 individuals, 5 of whom were homozygous, but no other lesions were found. In 1 sample from a patient with acute lymphoblastic leukaemia a smaller size transcript missing exon 9 was detected; a similar abnormality has been described previously in a patient with Wilms' tumour and the resultant protein shown to act in a dominant-negative manner. No mutations of the exon 9 donor or acceptor splice sites were found in this patient and the basis of the abnormal transcript remains obscure. We conclude that dominant-negative mutations of the zinc finger region of the WT1 gene are uncommon in CML blast crisis. Abnormalities of this gene may, however, contribute to a small proportion of cases of de novo acute leukaemia.
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PMID:Dominant-negative mutations of the Wilms' tumour predisposing gene (WT1) are infrequent in CML blast crisis and de novo acute leukaemia. 922 90

The Wilms tumor (WT1) gene has been reported to be preferentially expressed in acute leukemia cells, regardless of leukemia subtype and chronic myelogenous leukemia cells in blast crisis, but not in normal cells. This finding suggests strongly that WT1 protein is a potential target of immunotherapy for human leukemia. In this study, we established a CD8(+) cytotoxic T-lymphocyte (CTL) clone directed against a WT1-derived peptide and examined its immunologic actions on leukemia cells. A CD8(+) CTL clone, designated TAK-1, which lysed autologous cells loaded with a WT1-derived 9-mer peptide consisting of the HLA-A24 (HLA-A*2402)-binding motifs was established by stimulating CD8(+) T lymphocytes from a healthy individual repeatedly with WT1 peptide-pulsed autologous dendritic cells. TAK-1 was cytotoxic to HLA-A24-positive leukemia cells expressing WT1, but not to HLA-A24-positive lymphoma cells that did not express WT1, HLA-A24-negative leukemia cells, or HLA-A24-positive normal cells. Treating leukemia cells with an antisense oligonucleotide complementary to the WT1 gene resulted in reduced TAK-1-mediated cytotoxicity, suggesting that target antigen of TAK-1 on leukemia cells is the naturally processed WT1 peptide in the context of HLA-A24. TAK-1 did not inhibit colony formation by normal bone marrow cells of HLA-A24-positive individuals. Because WT1 is overexpressed ubiquitously in various types of leukemia cells, but not in normal cells, immunotherapy using WT1 peptide-specific CTL clones should be an efficacious treatment for human leukemia. (Blood. 2000;95:286-293)
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PMID:HLA class I-restricted lysis of leukemia cells by a CD8(+) cytotoxic T-lymphocyte clone specific for WT1 peptide. 1060 14

Continuous Wilms' tumor gene (WT1) expression is a typical feature of leukemic blasts in AML, ALL, and blast crisis CML patients. It is easily detectable by a variety of RT-PCR protocols, which differ mainly in their sensitivity. The nuclear WT1 protein can be found in blasts of approximately 50-60% of acute leukemia patients at diagnosis. Conversely, WT1 is only transiently expressed in normal hemopoiesis. Early CD34+ hemopoietic progenitors express WT1, whereas no WT1 mRNA transcripts can be found in mature blood cells and differentiation-induced committed CD34- progenitors. As a powerful complementary diagnostic tool, testing for WT1 expression can be helpful to discriminate between eosinophilic leukemia (EoL) patients and patients with idiopathic hypereosinophilic syndromes. Conflicting data about the usefulness of testing for WT1 expression to monitor minimal residual disease (MRD) in treated leukemia patients will be discussed. Finally, research strategies to circumvent shortcomings in detecting leukemia-associated WT1 expression will be outlined.
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PMID:Analysis of Wilms tumor gene (WT1) expression in acute leukemia patients with special reference to the differential diagnosis between eosinophilic leukemia and idiopathic hypereosinophilic syndromes. 1067

Hematologic malignancies such as acute and chronic myeloid leukemia are characterized by the malignant transformation of immature CD34(+) progenitor cells. Transformation is associated with elevated expression of the Wilm's tumor gene encoded transcription factor (WT1). Here we demonstrate that WT1 can serve as a target for cytotoxic T lymphocytes (CTL) with exquisite specificity for leukemic progenitor cells. HLA-A0201- restricted CTL specific for WT1 kill leukemia cell lines and inhibit colony formation by transformed CD34(+) progenitor cells isolated from patients with chronic myeloid leukemia (CML), whereas colony formation by normal CD34(+) progenitor cells is unaffected. Thus, the tissue-specific transcription factor WT1 is an ideal target for CTL-mediated purging of leukemic progenitor cells in vitro and for antigen-specific therapy of leukemia and other WT1-expressing malignancies in vivo.
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PMID:Selective elimination of leukemic CD34(+) progenitor cells by cytotoxic T lymphocytes specific for WT1. 1073 85

The Wilms' tumour gene (WT1) has been suggested as a powerful parameter for molecular monitoring of minimal residual disease (MRD) in leukaemias. However, molecular monitoring via WT1 RNA levels is far from being routinely performed, which is possibly owing to the complex and inaccurate quantitative reverse transcription polymerase chain reaction (RT-PCR) procedures. Using a newly-developed quantitative real time RT-PCR, we measured WT1 transcripts in peripheral blood leucocytes of patients with acute myeloid (AML), acute lymphoid (ALL) and chronic myeloid leukaemia (CML). While healthy blood donors did not show measurable amounts of WT1 transcripts, WT1 RNA levels were detectable in all types of leukaemia. Furthermore, intraindividual WT1 transcript kinetics were exclusively dependent on disease progression, treatment and subsequent disease outcome. Using this approach, we could distinguish between treatment response and failure within the first days of therapeutic intervention. Moreover, gradually rising WT1 levels over a period of weeks and months paralleled long-term disease progression and appeared to be a prognostic indicator for subsequent clinical relapse. A linear correlation between quantities of WT1 and bcr/abl fusion transcripts could be seen in CML. We conclude that quantitative assessment of WT1 transcripts using real-time PCR is an appropriate method for molecular monitoring of AML, ALL and CML, and can be used independently for both short- and long-term monitoring of leukaemia patients.
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PMID:Fluorescent 5'-exonuclease assay for the absolute quantification of Wilms' tumour gene (WT1) mRNA: implications for monitoring human leukaemias. 1152 49

The Wilms' tumor (WT1) gene encodes a zinc finger transcription factor, which is preferentially expressed in acute leukemia cells and chronic myelogenous leukemia cells in blast crisis, but not in most normal cells. These findings strongly suggest that WT1 is a potential target of immunotherapy for human leukemia. We have established a CD8+ cytotoxic T lymphocyte (CTL) clone, designated TAK-1, which is specific for a WT1-derived 9-mer peptide consisting of HLA-A24-binding anchor motifs. TAK-1 lysed both HLA-A24-positive allogeneic cells and autologous cells that were loaded with a WT1-derived peptide. TAK-1 was cytotoxic to HLA-A24-positive leukemia cells, but not to HLA-A24-positive lymphoma cells that did not express WT1, to HLA-A24-negative leukemia cells, or to HLA-A24-positive normal cells. Treating leukemia cells with an antisense oligonucleotide complementary to WT1 reduced TAK-1-mediated cytotoxicity. TAK-1 did not inhibit colony formation of HLA-A24-positive normal bone marrow cells. Recently, other groups have also reported the establishment of HLA-A2-restricted anti-leukemic CTLs specific for WT1-derived peptide. In addition, a murine model of immunotherapy against WT1-expressing tumors has been reported. Recent studies have demonstrated that WT1 is also aberrantly expressed in various kinds of cancer cells. Taken together, these results suggest that immunotherapy targeting WT1 should be effective against both solid tumors and leukemia.
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PMID:Immunotherapy for leukemia targeting the Wilms' tumor gene. 1169 91

Wild-type Wilms' tumor gene WT1 is expressed at high levels not only in most of acute myelocytic, acute lymphocytic, and chronic myelocytic leukemia, but also in various types of solid tumors including lung cancer. We tested the ability of the gene product (WT1) to serve as a target antigen for tumor specific immunotherapy both in human in vitro system and mouse in vivo system. In the latter, we can evaluate the efficacy and the side effects of WT1 vaccination in vivo. In the human in vitro system, two WT1 peptides that contain HLA-A2.1 binding anchor motifs were determined to bind to HLA-A2.1 molecules. Peripheral blood mononuclear cells (PBMC) from an HLA-A2.1-psitive donor were repeatedly stimulated in vitro with TAP-deficient T2 cells pulsed with each of these two peptides, and CD8-positive cytotoxic T lymphocytes (CTLs) that specifically lyse WT1-expressing, HLA-A2.1-positive tumor cells were induced. Other groups also have succeeded in generating CTLs which specifically lyse WT1-expressing leukemia cells, and which do not inhibit colony-formation of normal hematopoietic cells that express WT1 at physiological levels. In the mouse in vivo system, immunization of C57BL/6 mice with one WT1 peptide with relatively high binding affinity for H-2D(b) molecules, which contain H-2D(b) binding anchor motifs, induced CTLs, which specifically lysed WT1-expressing tumor cells in an H-2D(b)-restricted manner. Furthermore, mice immunized with the WT1 peptide (peptide vaccination) or WT1 cDNA (DNA vaccination) rejected challenges by WT1-expressing tumor cells and survived with no signs of auto-aggression to WT1-expressing normal organs by the induced CTLs. The WT1 protein has been identified as a novel tumor antigen and recent investigations provide a rationale for developing WT1-based adoptive T cell therapy and vaccination against various kinds of malignant neoplasms.
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PMID:WT1 as a novel target antigen for cancer immunotherapy. 1218 20

Using the allo-restricted T-cell approach to circumvent tolerance, we have previously identified a cytotoxic T-lymphocyte (CTL) epitope in the transcription factor Wilms tumor antigen 1 (WT1) presented by HLA-A0201 (A2) class I molecules. Here we describe an additional A2-presented epitope and show that CTLs against both epitopes kill WT1-expressing leukemia cell lines. Colony-forming assays demonstrated that both types of CTL killed CD34(+) progenitor cells from A2(+) leukemia patients, but not from A2(+) healthy individuals. The long-term culture-initiating cell (LTC-IC) assay was used to analyze the killing activity of WT1-specific CTLs against the more immature fraction of CD34(+) cells. The CTLs killed LTC-ICs of patients with chronic myelogenous leukemia (CML), whereas the function of normal CD34(+) progenitor/stem cells was not inhibited. Together, the data show that CTLs specific for 2 distinct peptide epitopes of WT1 can discriminate between normal and leukemia LTC-ICs, suggesting that such CTLs have the potential to selectively kill CML progenitor/stem cells.
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PMID:Two distinct HLA-A0201-presented epitopes of the Wilms tumor antigen 1 can function as targets for leukemia-reactive CTL. 1241 26

The advanced understanding of the molecular biology and immunology of chronic myeloid leukemia (CML) has led to novel therapeutic strategies unique to this disease. CML responds to immune-mediated therapies, including stem cell transplantation, donor lymphocyte infusion (DLI), and interferon alfa. T cells and other immune effectors are implicated in the mechanisms of action of these immune therapies. Recently, clinical observations supported by laboratory data have demonstrated the presence of CML-specific T cells in patients. Several proteins may potentially act as leukemia-specific antigens for major histocompatibility complex (MHC)-restricted cytotoxicity in CML, and active specific therapies (vaccines) are in development. Antigens under investigation include bcr-abl, PR1, Wilms tumor protein (WT1), minor histocompatibility antigens (mH), CML-66, CML-28, and survivin. Other strategies target vascular endothelial growth factor (VEGF) and heat shock protein 90 (Hsp90) inhibitors or make use of CML-derived dendritic cells (DC).
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PMID:Novel targeted and immunotherapeutic strategies in chronic myeloid leukemia. 1256 15


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