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)

Bcr-abl signals for leukemogenesis of chronic myeloid leukemia (CML) and activates ras. Since the function of promyelocytic leukemia protein (pml) is provoked by ras to promote apoptosis and senescence in untransformed cells, the function is probably masked in CML. Imatinib specifically inhibits bcr-abl and induces apoptosis of CML cells. As reported previously, p53(wild) CML was more resistant to imatinib than that lacking p53. Here, we searched for an imatinib-induced p53 independent proapoptotic mechanism. We found imatinib up-regulated phosphorylation of p38 mitogen-activated protein kinase (MAPK), checkpoint kinase 2 (chk2) and transactivation-competent (TA) p73; expression of pml and bax; formation of PML-nuclear body (NB); and co-localization of TAp73/PML-NB in p53-nonfunctioning K562 and p53(mutant) Meg-01 CML cells, but not in BCR-ABL(-) HL60 cells. In K562 cells, with short interfering RNAs (siRNAs), knockdown of pml led to dephosphorylation of TAp73. Knockdown of either pml or TAp73 abolished the imatinib-induced apoptosis. Inhibition of p38 MAPK with SB203580 led to dephosphorylation of TAp73, abolishment of TAp73/PML-NB co-localization, and the subsequent apoptosis. Conversely, interferon alpha-2a (IFNalpha), which increased phosphrylated TAp73 and TAp73/PML-NB co-localization, increased additively apoptosis with imatinib. The imatinib-induced TAp73/PML-NB co-localization was accompanied by co-immpunoprecipitation of TAp73 with pml. The imatinib-induced co-localization was also found in primary CML cells from 3 of 6 patients, including 2 with p53(mutant) and one with p53(wild). A novel p53-independent proapoptotic mechanism using p38 MAPK /pml/TAp73 axis with a step processing at PML-NB and probably with chk2 and bax being involved is hereby evident in some imatinib-treated CML cells.
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PMID:Pml and TAp73 interacting at nuclear body mediate imatinib-induced p53-independent apoptosis of chronic myeloid leukemia cells. 1929 93

The BCR/ABL fusion oncogene found in Philadelphia-positive leukemia exists in three principle forms: p190, p210 and p230. P210 BCR/ABL is commonly found in patients with chronic myelogenous leukemia (CML) and is further categorized into b3a2 or b2a2 subtypes on the basis of the BCR breakpoint. Although these 2 subtypes may be clinically heterogeneous, only the b3a2 BCR/ABL gene has been extensively studied at the molecular and cellular levels. In the present study, we compared the in vivo leukemogenic activity of the b3a2 and b2a2 BCR/ABL genes by using lentiviral transduction/transplantation mouse models. Lineage-depleted bone marrow cells of BALB/c mice were transduced with a lentiviral vector including either b2a2 or b3a2 BCR/ABL cDNA and then transplanted into lethally irradiated mice. In this model, p210 BCR/ABL subtype developed only B220(+), CD3e(-), Gr1(-), and Mac1(-) B-cell acute lymphoblastic leukemia but not myeloid leukemia. There were no differences in the incidence of leukemogenesis, the white blood cell count, the percentage of blast cells, or the survival rates between the b2a2 and b3a2 groups. We have demonstrated that b2a2-type BCR/ABL has leukemogenic activity similar to that of b3a2-type BCR/ABL.
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PMID:Leukemogenesis of b2a2-type p210 BCR/ABL in a bone marrow transplantation mouse model using a lentiviral vector. 1960 20

Acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) both represent highly heterogeneous entities on the basis of diverse cyto- and molecular genetic alterations with considerable influence on prognosis and therapeutic decisions. In recent years, insights into the complex network of molecular markers underlying this diversity have shown marked progress due to the detection of novel mutations, such as nucleophosmin gene (NPM1) in AML, and due to the description of cooperation pathways in leukemogenesis. Also, targeted therapeutic strategies are continuously expanding as illustrated by the tyrosine kinase inhibitor (TKI) imatinib for BCR-ABL positive ALL. Thus, molecular analysis based on various techniques, such as polymerase chain reaction (PCR) has become an essential part of the diagnostic panel for acute leukemia. In addition, cytomorphology, cytogenetics, fluorescence in situ hybridization (FISH), and immunophenotyping with multiparameter flow cytometry (MFC) need to be applied for diagnosis. During the course of disease, the residual leukemic cell load can be monitored by highly sensitive quantitative PCR techniques ("real-time PCR"). At present, new techniques, such as high throughput sequencing (next generation sequencing, NGS) or gene expression profiling with microarrays are being explored for use in hematological malignancies, and are being evaluated in preclinical studies. This demonstrates that molecular diagnostics for acute leukemias are in continuous development. This review summarizes the most important recurrent molecular markers seen in acute leukemias, their role in prognosis and therapy and provides an overview on the relevant PCR techniques.
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PMID:Molecular diagnostics in acute leukemias. 1981 44

The clinical management of patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has been challenging primarily due to the aggressive nature of the disease and limited effective treatment options. The outcome for patients who receive conventional chemotherapy alone is poor, with remission duration of around 12 months and disease-free survival (DFS) rates of not more than 10%. Allogeneic stem cell transplantation (alloSCT) has been the only known curative treatment option, but is limited by the availability of a matched donor and the risk of treatment-related mortality. Given the role of BCR-ABL in the leukemogenesis of Ph+ ALL, current treatments have focused on inhibition of this oncogenic tyrosine kinase. Early studies demonstrate that the use of the BCR-ABL tyrosine kinase inhibitor (TKI), imatinib, before alloSCT results in improved response rates and DFS when combined with standard chemotherapy regimens. Remission duration also is improved when combination chemotherapy and imatinib are administered intensively, even in the absence of allogeneic stem cell transplant. However, resistant disease remains an important problem, and the mechanisms underlying resistance in Ph+ ALL are multifactorial. Novel TKIs are currently under development and are effective in some patients with imatinib-resistant disease. The dual BCR-ABL/SRC family kinase inhibitor, dasatinib, has shown promising activity in the treatment of Ph+ ALL after imatinib failure and has recently been approved in this indication. Other TKI-based therapies are also showing potential in imatinib-resistant disease. This article reviews current and emerging treatments in Ph+ ALL.
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PMID:Current treatment options for adult patients with Philadelphia chromosome-positive acute lymphoblastic leukemia. 2000 Dec 32

Copy number losses in chromosome arm 9p are well-known aberrations in malignancies, including leukemias. The CDKN2A gene is suggested to play a key role in these aberrations. In this study overviewing 9p losses in hematologic neoplasias, we introduce the term focal 9p instability to indicate multiple areas of copy number loss or homozygous loss within a larger heterozygous one in 9p. We have used microarray comparative genomic hybridization to study patients with acute lymphoblastic leukemia (ALL, n = 140), acute myeloid leukemia (n = 50), chronic lymphocytic leukemia (n = 20), and myelodysplastic syndromes (n = 37). Our results show that 9p instability is restricted to ALL. In total, 58/140 (41%) patients with ALL had a loss in 9p. The 9p instability was detected in 19% of the patients with ALL and always included homozygous loss of CDKN2A along with loss of CDKN2B. Other possibly important genes included MTAP, IFN, MLLT3, JAK2, PTPLAD2, and PAX5. 13/27 (48%) patients with the instability had the BCR/ABL1 fusion gene or other oncogene-activating translocation or structural aberrations. Two patients had homozygous loss of hsa-mir -31, a microRNA known to regulate IKZF1. IKZF1 deletion at 7p12.1 was seen in 10 (37%) patients with the 9p instability. These findings suggest that, in ALL leukemogenesis, loss of CDKN2A and other target genes in the instability region is frequently associated with BCR/ABL1 and IKZF1 dysfunction. The multiple mechanisms leading to 9p instability including physical or epigenetic loss of the target genes, loss of the microRNA cluster, and the role of FRA9G fragile site are discussed.
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PMID:Focal 9p instability in hematologic neoplasias revealed by comparative genomic hybridization and single-nucleotide polymorphism microarray analyses. 2001 97

Entire ABL1 gene deletion without BCR/ABL1 rearrangement is a rare phenomenon, with only four cases previously reported. Here we describe a fifth case of ABL1 deletion without BCR/ABL1 rearrangement in an adolescent patient with precursor B-cell lymphoblastic leukemia (B-ALL) and review the relevant literature. It is not clear how ABL1 deletion affects leukemogenesis; however, it is plausible that ABL1 deletion without BCR/ABL1 rearrangement is a rare but recurrent genetic abnormality in precursor B-ALL patients. Further studies are needed to evaluate the extent of the submicroscopic defects in chromosome 9 including ABL1 gene deletion, as well as treatment response and prognosis in long-term follow-up of such patients.
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PMID:ABL1 gene deletion without BCR/ABL1 rearrangement in a young adolescent with precursor B-cell acute lymphoblastic leukemia: clinical study and literature review. 2008 57

mTOR-generated signals play critical roles in growth of leukemic cells by controlling mRNA translation of genes that promote mitogenic responses. Despite extensive work on the functional relevance of rapamycin-sensitive mTORC1 complexes, much less is known on the roles of rapamycin-insensitive (RI) complexes, including mTORC2 and RI-mTORC1, in BCR-ABL-leukemogenesis. We provide evidence for the presence of mTORC2 complexes in BCR-ABL-transformed cells and identify phosphorylation of 4E-BP1 on Thr37/46 and Ser65 as RI-mTORC1 signals in primary chronic myelogenous leukemia (CML) cells. Our studies establish that a unique dual mTORC2/mTORC1 inhibitor, OSI-027, induces potent suppressive effects on primitive leukemic progenitors from CML patients and generates antileukemic responses in cells expressing the T315I-BCR-ABL mutation, which is refractory to all BCR-ABL kinase inhibitors currently in clinical use. Induction of apoptosis by OSI-027 appears to negatively correlate with induction of autophagy in some types of BCR-ABL transformed cells, as shown by the induction of autophagy during OSI-027-treatment and the potentiation of apoptosis by concomitant inhibition of such autophagy. Altogether, our studies establish critical roles for mTORC2 and RI-mTORC1 complexes in survival and growth of BCR-ABL cells and suggest that dual therapeutic targeting of such complexes may provide an approach to overcome leukemic cell resistance in CML and Ph+ ALL.
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PMID:Critical roles for mTORC2- and rapamycin-insensitive mTORC1-complexes in growth and survival of BCR-ABL-expressing leukemic cells. 2061 57

In recent years, there have been substantial research advances on the mechanisms by which BCR-ABL transforms hematopoietic cells and promotes leukemic cell growth and survival. Among the diverse signaling cascades activated by BCR-ABL, the mTOR pathway plays a critical role in mRNA translation of genes that promote leukemogenesis and mitogenic responses. We have recently shown that dual targeting of mTORC1 and mTORC2 complexes using a catalytic mTOR inhibitor, OSI-027, results in generation of potent antileukemic effects against BCR-ABL transformed cells. Such effects were also seen in cells expressing the T315I mutation, which is resistant to all currently approved BCR-ABL kinase inhibitors. Our studies also demonstrate that such dual catalytic inhibition of mTORC2 and mTORC1 complexes in BCR-ABL-expressing K562 cells results in induction of autophagy, and that inhibition of the autophagic process using chloroquine promotes apoptosis of these cells. Altogether, our studies suggest that autophagy may be a limiting factor for the induction of apoptosis during dual mTORC2-mTORC1 targeting, in at least some types of BCR-ABL-expressing cells and have raised the potential of combinations of catalytic inhibitors of mTOR with autophagy inhibitors for the treatment of refractory Ph(+) leukemias.
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PMID:Induction of autophagy by dual mTORC1-mTORC2 inhibition in BCR-ABL-expressing leukemic cells. 2069 67

Many biological and clinical features of chronic myeloid leukemia make it as a paradigm of rational drug design in human cancer. Chronic myeloid leukemia was the first malignancy to be linked to a clear genetic anomaly, the Philadelphia chromosome and, at present, it is probably the best understood of all human malignancies. Studies of the disease pathology revealed that the molecular consequence of the Philadelphia translocation is a BCR-ABL chimeric gene, which encodes a constitutively active tyrosine kinase with wholesale range of biological activities. Animal models have validated the direct role of the BCR-ABL protein in malignant transformation and subsequent research confirmed that its enhanced tyrosine kinase activity is essential and sufficient for the leukemogenesis. The very existence of a single genetic abnormality, presented in essentially all patients with the disease, made it an effective target for molecularly designed therapeutic approaches for the disease. The advent of tyrosine kinase inhibitors, designed specifically to inhibit the tyrosine kinase activity of the BCR-ABL oncoprotein, represents one of the major innovations in cancer therapy and may serve as a model for, how discoveries of disease pathogenesis may be translated into the development of successful targeted therapies in cancer medicine.
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PMID:Targeting the BCR-ABL tyrosine kinase in chronic myeloid leukemia as a model of rational drug design in cancer. 2108 33

Chronic myeloid leukemia (CML) progresses from a chronic phase to a deadly blast crisis phase. While it is known that BCR-ABL initiates the disease and that secondary molecular and genetic abnormalities likely contribute to progression of the disease to blast crisis, details regarding the mechanism(s) of blast phase progression are lacking. Two recent reports identify Musashi 2 (Msi2) as a key regulator in the progression of CML from the chronic phase to blast crisis. These reports demonstrated that the cell fate determination protein, Numb, was downregulated in blast crisis CML and that exogenous expression of Numb inhibited leukemogenesis. Correspondingly, Msi2 was shown to be upregulated in blast crisis CML and to negatively regulate expression of Numb. Exogenous expression of Msi2 enhanced the formation of an aggressive immature leukemia induced by BCR-ABL. High expression of Msi2 was also found in leukemic cells of AML patients and elevated Msi2 expression was shown to associate with poor prognosis in both AML and CML. These reports together highlight the apparent role of the Musashi-Numb pathway in regulating the formation of aggressive myeloid leukemia, and thus provide a potential molecular mechanism for the transition of chronic phase CML to the deadly blast crisis. Importantly, this work suggests this pathway may provide targets for future therapies that are desperately needed for aggressive forms of myeloid leukemia.
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PMID:Aggressive myeloid leukemia formation is directed by the Musashi 2/Numb pathway. 2108 60


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