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Gurska LM, Ames K, Gritsman K. Signaling Pathways in Leukemic Stem Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1143:1-39. [PMID: 31338813 PMCID: PMC7249489 DOI: 10.1007/978-981-13-7342-8_1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hematopoietic stem cells (HSCs) and leukemic stem cells (LSCs) utilize many of the same signaling pathways for their maintenance and survival. In this review, we will focus on several signaling pathways whose roles have been extensively studied in both HSCs and LSCs. Our main focus will be on the PI3K/AKT/mTOR pathway and several of its regulators and downstream effectors. We will also discuss several other signaling pathways of particular importance in LSCs, including the WNT/β-catenin pathway, the NOTCH pathway, and the TGFβ pathway. For each of these pathways, we will emphasize differences in how these pathways operate in LSCs, compared to their function in HSCs, to highlight opportunities for the specific therapeutic targeting of LSCs. We will also highlight areas of crosstalk between multiple signaling pathways that may affect LSC function.
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Affiliation(s)
- Lindsay M Gurska
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Kristina Ames
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Kira Gritsman
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA.
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA.
- Department of Medical Oncology, Montefiore Hospital, Bronx, New York, USA.
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2
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Su E, Han X, Jiang G. The Transforming Growth Factor Beta 1/SMAD Signaling Pathway Involved in Human Chronic Myeloid Leukemia. TUMORI JOURNAL 2018; 96:659-66. [DOI: 10.1177/030089161009600503] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Transforming growth factor beta 1 (TGF-β1) is the prototypic member of a large family of structurally related pleiotropic-secretedcytokines. The TGF-β1/SMAD signaling pathway usually participates in a wide range of cellular processes such as growth, proliferation, differentiation and apoptosis. Upon binding onTGF-β1, the dimerized TGF-β type II receptors recruit and phosphorylate the TGF-β type I receptors, which phosphorylate the receptor-regulated SMAD (SMAD2 and SMAD3) presented by the SMAD anchor for receptor activation. The phosphorylated receptor-regulated SMAD form heterologous complexes with the common-mediator SMAD (SMAD4) and subsequently translocate into the nucleus, where they interact with other transcription factors to regulate the expression of target genes. This multi-functional signaling pathway modulated by various elements with complex mechanisms at different levels is also inevitably involved in cancer. We herein present data on the role of the TGF-β1/SMAD signaling pathway in human chronic myeloid leukemia and explain the potent biological effects of TGF-β1 on leukemia cells. The paper is based on a review of articles selected from Cancerline and Medline data bases. The constitutively active tyrosine kinase produced by the specific Bcr-Abl fusion gene on the Philadelphia chromosome can enhance the resistance of malignant cells to TGF-β1-induced growth inhibition and apoptosis, which contributes to enhancement of proteasomal degradation of p27. However, overexpression of the EVI1 gene, which is also caused by Bcr-Abl, can recruit the C-terminal binding protein and histone deacetylase to prevent the MH2 domain on SMAD3. The later is essential for transcription activation on target genes and leads to blockage of the TGF-β1/SMAD signaling pathway. Some studies have indicated that certain therapeutic agents applied in clinical treatment can inhibit proliferation and promote differentiation of leukemia cells by way of modulation of the TGF-β1/SMAD signal pathway. For example, arsenic trioxide can promote specific degradation of the AML1/MDS1/EVI1 oncoprotein and inhibit the proliferation of leukemia cells. However, specific histone deacetylase inhibitors can interrupt the effect of histone deacetylase to alleviate EVI1-mediated suppression of TGF-β1/SMAD signaling. The tyrosine kinase inhibitor in the target therapy of chronic myeloid leukemia can effectively inhibit the tyrosine kinase activity of Bcr-Abl and induce suppression on the TGF-β1/SMAD signaling pathway. The TGF-β1/SMAD signaling pathway plays an important role in chronic myeloid leukemia cells and leads the leukemia cells to growth inhibition, differentiation and apoptosis. The positive influence of the TGF-β1/SMAD signaling pathway in chronic myeloid leukemia is fairly significant, and its potential effects in clinical treatment will bring about definite benefits. Since it is a complex signaling pathway widely involved in many aspects of cellular activities, further study and comprehensive analysis of the TGF-β1/SMAD signaling pathway are imperative and will have a guiding significance in research and clinical applications. It is an exciting area for future research. Free full text available at www.tumorionline.it
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Affiliation(s)
- Enyu Su
- Key Laboratory for Modern Medicine and Technology of Shandong Province, Institute of Basic Medicine
| | - Xiao Han
- Shandong Cancer Hospital and Institute, Shandong Academy of Medical Sciences, Jinan, Shandong, P.R. China
| | - Guosheng Jiang
- Key Laboratory for Modern Medicine and Technology of Shandong Province, Institute of Basic Medicine
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Moreno-Lorenzana D, Avilés-Vazquez S, Sandoval Esquivel MA, Alvarado-Moreno A, Ortiz-Navarrete V, Torres-Martínez H, Ayala-Sánchez M, Mayani H, Chavez-Gonzalez A. CDKIs p18(INK4c) and p57(Kip2) are involved in quiescence of CML leukemic stem cells after treatment with TKI. Cell Cycle 2017; 15:1276-87. [PMID: 26985855 PMCID: PMC4889309 DOI: 10.1080/15384101.2016.1160976] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Chronic Myeloid Leukemia (CML) is sustained by a small population of cells with stem cell characteristics known as Leukemic Stem Cells that are positive to BCR-ABL fusion protein, involved with several abnormalities in cell proliferation, expansion, apoptosis and cell cycle regulation. Current treatment options for CML involve the use of Tirosine Kinase Inhibitor (Imatinib, Nilotinib and Dasatinib), that efficiently reduce proliferation proliferative cells but do not kill non proliferating CML primitive cells that remain and contributes to the persistence of the disease. In order to understand the role of Cyclin Dependent Kinase Inhibitors in CML LSC permanence after TKI treatment, in this study we analyzed cell cycle status, the levels of several CDKIs and the subcellular localization of such molecules in different CML cell lines, as well as primary CD34+CD38−lin− LSC and HSC. Our results demonstrate that cellular location of p18INK4c and p57Kip2 seems to be implicated in the antiproliferative activity of Imatinib and Dasatinib in CML cells and also suggest that the permanence of quiescent stem cells after TKI treatment could be associated with a decrease in p18INK4c and p57Kip2 nuclear location. The differences in p18INK4cand p57Kip2activities in CML and normal stem cells suggest a different cell cycle regulation and provide a platform that could be considered in the development of new therapeutic options to eliminate LSC.
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Affiliation(s)
- Dafne Moreno-Lorenzana
- a Oncology Research Unit , Oncology Hospital, National Medical Center , Mexican Institute for Social Security , Mexico City , Mexico.,b Molecular Biomedicine Department , CINVESTAV , Mexico City , Mexico
| | - Sócrates Avilés-Vazquez
- a Oncology Research Unit , Oncology Hospital, National Medical Center , Mexican Institute for Social Security , Mexico City , Mexico
| | - Miguel Angel Sandoval Esquivel
- a Oncology Research Unit , Oncology Hospital, National Medical Center , Mexican Institute for Social Security , Mexico City , Mexico
| | - Antonio Alvarado-Moreno
- c Thrombosis Haemostasia and Atherogenesis Research Unit , Mexican Institute for Social Security , Mexico City , Mexico
| | | | - Héctor Torres-Martínez
- d Department of Hip Surgery , Villa Coapa General Hospital , Mexican Institute for Social Security , Mexico City , Mexico
| | - Manuel Ayala-Sánchez
- e Department of Hematology , La Raza Medical Center , Mexican Institute for Social Security , Mexico City , Mexico
| | - Héctor Mayani
- a Oncology Research Unit , Oncology Hospital, National Medical Center , Mexican Institute for Social Security , Mexico City , Mexico
| | - Antonieta Chavez-Gonzalez
- a Oncology Research Unit , Oncology Hospital, National Medical Center , Mexican Institute for Social Security , Mexico City , Mexico
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4
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MicroRNA-139-5p regulates proliferation of hematopoietic progenitors and is repressed during BCR-ABL-mediated leukemogenesis. Blood 2016; 128:2117-2129. [PMID: 27605510 DOI: 10.1182/blood-2016-02-702464] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 09/02/2016] [Indexed: 12/13/2022] Open
Abstract
MicroRNAs (miRNAs) have emerged as important regulators of the immune system. However, despite this prominence, our understanding of the function of miRNAs in the early hematopoietic stages is incomplete. In this study, we found that miR-139-5p negatively regulated the proliferation of hematopoietic stem cells and progenitor cells and that downregulation of miR-139-5p expression was associated with hematopoietic malignancy, such as chronic myeloid leukemia (CML). Knockdown of miR-139-5p resulted in myeloid-biased differentiation with expansion of myeloid progenitor cells. In contrast, miR-139-5p expression inhibited the proliferation of hematopoietic progenitors and resulted in the remission of a CML-like disease that is induced by breakpoint cluster region-Abelson (BCR-ABL) transformation. We also found that Brg1 is a functional target of miR-139-5p and that Brg1 is involved in BCR-ABL-induced leukemogenesis. Thus, our results identify miR-139-5p as a key regulator of cellular proliferation during early hematopoiesis and suggest that it is a potent antileukemic molecule.
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Crivellaro S, Carrà G, Panuzzo C, Taulli R, Guerrasio A, Saglio G, Morotti A. The non-genomic loss of function of tumor suppressors: an essential role in the pathogenesis of chronic myeloid leukemia chronic phase. BMC Cancer 2016; 16:314. [PMID: 27184141 PMCID: PMC4869339 DOI: 10.1186/s12885-016-2346-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 05/09/2016] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Chronic Myeloid Leukemia was always referred as a unique cancer due to the apparent independence from tumor suppressors' deletions/mutations in the early stages of the disease. However, it is now well documented that even genetically wild-type tumor suppressors can be involved in tumorigenesis, when functionally inactivated. In particular, tumor suppressors' functions can be impaired by subtle variations of protein levels, changes in cellular compartmentalization and post-transcriptional/post-translational modifications, such as phosphorylation, acetylation, ubiquitination and sumoylation. Notably, tumor suppressors inactivation offers challenging therapeutic opportunities. The reactivation of an inactive and genetically wild-type tumor suppressor could indeed promote selective apoptosis of cancer cells without affecting normal cells. MAIN BODY Chronic Myeloid Leukemia (CML) could be considered as the paradigm for non-genomic loss of function of tumor suppressors due to the ability of BCR-ABL to directly promote functionally inactivation of several tumor suppressors. SHORT CONCLUSION In this review we will describe new insights on the role of FoxO, PP2A, p27, BLK, PTEN and other tumor suppressors in CML pathogenesis. Finally, we will describe strategies to promote tumor suppressors reactivation in CML.
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Affiliation(s)
- Sabrina Crivellaro
- Department of Clinical and Biological Sciences, University of Turin, San Luigi Hospital, Regione Gonzole 10, 10043, Orbassano, Italy
| | - Giovanna Carrà
- Department of Clinical and Biological Sciences, University of Turin, San Luigi Hospital, Regione Gonzole 10, 10043, Orbassano, Italy
| | - Cristina Panuzzo
- Department of Clinical and Biological Sciences, University of Turin, San Luigi Hospital, Regione Gonzole 10, 10043, Orbassano, Italy
| | - Riccardo Taulli
- Department of Oncology, University of Turin, Orbassano, Italy
| | - Angelo Guerrasio
- Department of Clinical and Biological Sciences, University of Turin, San Luigi Hospital, Regione Gonzole 10, 10043, Orbassano, Italy
| | - Giuseppe Saglio
- Department of Clinical and Biological Sciences, University of Turin, San Luigi Hospital, Regione Gonzole 10, 10043, Orbassano, Italy
| | - Alessandro Morotti
- Department of Clinical and Biological Sciences, University of Turin, San Luigi Hospital, Regione Gonzole 10, 10043, Orbassano, Italy.
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6
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Liu J, Lin J, Huang LF, Huang B, Xu YM, Li J, Wang Y, Zhang J, Yang WM, Min QH, Wang XZ. Differential expression and alternative splicing of cell cycle genes in imatinib-treated K562 cells. Tumour Biol 2015; 36:8127-36. [DOI: 10.1007/s13277-015-3493-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Accepted: 04/23/2015] [Indexed: 02/01/2023] Open
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Iriyama N, Hatta Y, Takei M. ETV6/ARG oncoprotein confers autonomous cell growth by enhancing c-Myc expression via signal transducer and activator of transcription 5 activation in the acute promyelocytic leukemia cell line HT93A. Leuk Lymphoma 2014; 56:2416-23. [PMID: 25373509 DOI: 10.3109/10428194.2014.982643] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We investigated the role of ETV6/ARG fusion gene by exposing the HT93A cell line to nilotinib. HT93A cells were cultured with or without nilotinib±50 ng/mL of granulocyte colony-stimulating factor (G-CSF). Nilotinib treatment inhibited cell growth by increasing the percentage of cells in G0/G1 phase through the decrease of phosphorylated signal transducer and activator of transcription 3 (STAT3) (Y705), STAT5 (Y694) and c-Myc expression. After stimulation with G-CSF, STAT5 but not STAT3 was significantly phosphorylated in both nilotinib-treated and untreated cells. Moreover, combination therapy with nilotinib and G-CSF returned the expression level of c-Myc, cell growth and cell cycle distribution to the control level. These findings suggest that the ETV6/ARG oncoprotein contributes to autonomous cell growth by compensating for the requirement of growth factor through activating STAT5 signaling, which leads to the up-regulation of c-Myc. Our data suggest that ETV6/ARG oncoprotein is a potential target in the treatment of leukemia.
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MESH Headings
- Cell Cycle Checkpoints/drug effects
- Cell Cycle Checkpoints/genetics
- Cell Cycle Proteins/genetics
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Gene Expression Regulation, Leukemic/drug effects
- Granulocyte Colony-Stimulating Factor/pharmacology
- Humans
- Leukemia, Promyelocytic, Acute/genetics
- Leukemia, Promyelocytic, Acute/metabolism
- Leukemia, Promyelocytic, Acute/pathology
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Phosphorylation
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins c-ets/genetics
- Proto-Oncogene Proteins c-ets/metabolism
- Proto-Oncogene Proteins c-myc/genetics
- Pyrimidines/pharmacology
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- STAT5 Transcription Factor/metabolism
- ETS Translocation Variant 6 Protein
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Affiliation(s)
- Noriyoshi Iriyama
- a Division of Hematology and Rheumatology, Department of Medicine , Nihon University School of Medicine , Tokyo , Japan
| | - Yoshihiro Hatta
- a Division of Hematology and Rheumatology, Department of Medicine , Nihon University School of Medicine , Tokyo , Japan
| | - Masami Takei
- a Division of Hematology and Rheumatology, Department of Medicine , Nihon University School of Medicine , Tokyo , Japan
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8
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Roy A, Banerjee S. p27 and Leukemia: Cell Cycle and Beyond. J Cell Physiol 2014; 230:504-9. [PMID: 25205053 DOI: 10.1002/jcp.24819] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 09/05/2014] [Indexed: 01/17/2023]
Affiliation(s)
- Anita Roy
- Biophysics and Structural Genomics Division; Saha Institute of Nuclear Physics; 1/AF Bidhannagar Kolkata West Bengal India
| | - Subrata Banerjee
- Biophysics and Structural Genomics Division; Saha Institute of Nuclear Physics; 1/AF Bidhannagar Kolkata West Bengal India
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9
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Chen Q, Chen K, Guo G, Li F, Chen C, Wang S, Nalepa G, Huang S, Chen JL. A critical role of CDKN3 in Bcr-Abl-mediated tumorigenesis. PLoS One 2014; 9:e111611. [PMID: 25360622 PMCID: PMC4216094 DOI: 10.1371/journal.pone.0111611] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 09/26/2014] [Indexed: 01/28/2023] Open
Abstract
CDKN3 (cyclin-dependent kinase inhibitor 3), a dual specificity protein phosphatase, dephosphorylates cyclin-dependent kinases (CDKs) and thus functions as a key negative regulator of cell cycle progression. Deregulation or mutations of CDNK3 have been implicated in various cancers. However, the role of CDKN3 in Bcr-Abl-mediated chronic myelogenous leukemia (CML) remains unknown. Here we found that CDKN3 acts as a tumor suppressor in Bcr-Abl-mediated leukemogenesis. Overexpression of CDKN3 sensitized the K562 leukemic cells to imanitib-induced apoptosis and dramatically inhibited K562 xenografted tumor growth in nude mouse model. Ectopic expression of CDKN3 significantly reduced the efficiency of Bcr-Abl-mediated transformation of FDCP1 cells to growth factor independence. In contrast, depletion of CDKN3 expression conferred resistance to imatinib-induced apoptosis in the leukemic cells and accelerated the growth of xenograph leukemia in mice. In addition, we found that CDKN3 mutant (CDKN3-C140S) devoid of the phosphatase activity failed to affect the K562 leukemic cell survival and xenografted tumor growth, suggesting that the phosphatase of CDKN3 was required for its tumor suppressor function. Furthermore, we observed that overexpression of CDKN3 reduced the leukemic cell survival by dephosphorylating CDK2, thereby inhibiting CDK2-dependent XIAP expression. Moreover, overexpression of CDKN3 delayed G1/S transition in K562 leukemic cells. Our results highlight the importance of CDKN3 in Bcr-Abl-mediated leukemogenesis, and provide new insights into diagnostics and therapeutics of the leukemia.
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Affiliation(s)
- Qinghuang Chen
- College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Ke Chen
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, China
| | - Guijie Guo
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, China
| | - Fang Li
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, China
| | - Chao Chen
- College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Song Wang
- College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Grzegorz Nalepa
- Department of Pediatrics and Division of Pediatric Hematology-Oncology, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Shile Huang
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Ji-Long Chen
- College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences (CAS), Beijing, China
- * E-mail:
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Abstract
Recent studies have revealed that p27, a nuclear cyclin-dependent kinase (Cdk) inhibitor and tumor suppressor, can acquire oncogenic activities upon mislocalization to the cytoplasm. To understand how these antagonistic activities influence oncogenesis, we dissected the nuclear and cytoplasmic functions of p27 in chronic myeloid leukemia (CML), a well-characterized malignancy caused by the BCR-ABL1 tyrosine kinase. p27 is predominantly cytoplasmic in CML and nuclear in normal cells. BCR-ABL1 regulates nuclear and cytoplasmic p27 abundance by kinase-dependent and -independent mechanisms, respectively. p27 knockdown in CML cell lines with predominantly cytoplasmic p27 induces apoptosis, consistent with a leukemogenic role of cytoplasmic p27. Accordingly, a p27 mutant (p27(CK-)) devoid of Cdk inhibitory nuclear functions enhances leukemogenesis in a murine CML model compared with complete absence of p27. In contrast, p27 mutations that enhance its stability (p27(T187A)) or nuclear retention (p27(S10A)) attenuate leukemogenesis over wild-type p27, validating the tumor-suppressor function of nuclear p27 in CML. We conclude that BCR-ABL1 kinase-dependent and -independent mechanisms convert p27 from a nuclear tumor suppressor to a cytoplasmic oncogene. These findings suggest that cytoplasmic mislocalization of p27 despite BCR-ABL1 inhibition by tyrosine kinase inhibitors may contribute to drug resistance, and effective therapeutic strategies to stabilize nuclear p27 must also prevent cytoplasmic mislocalization.
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11
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Roy A, Lahiry L, Banerjee D, Ghosh M, Banerjee S. Increased cytoplasmic localization of p27(kip1) and its modulation of RhoA activity during progression of chronic myeloid leukemia. PLoS One 2013; 8:e76527. [PMID: 24098519 PMCID: PMC3788125 DOI: 10.1371/journal.pone.0076527] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 09/01/2013] [Indexed: 01/19/2023] Open
Abstract
The role of p27kip1 in Chronic Myeloid Leukemia (CML) has been well studied in relation to its function as a cell cycle inhibitor. However, its cytoplasmic function especially in CML remains to be seen. We studied the localization of p27kip1 and its function during the progression of CML from chronic to blast phase. Our investigations revealed an increased localization of p27kip1 in the cytoplasm of CD34+ cells in the blast phase compared to chronic phase. Cytoplasmic p27kip1 was found to modulate RhoA activity in CD34+ stem and progenitor cells. Further, RhoA activity was shown to be dependent on cytoplasmic p27kip1 which in turn was dependent on p210Bcr-Abl kinase activity. Interestingly, RhoA activity was observed to affect cell survival in the presence of imatinib through the SAPK/JNK pathway. Accordingly, inhibition of SAPK/JNK pathway using SP600125 increased apoptosis of K562 cells in presence of imatinib. Our results, for the first time, thus reveal a crucial link between cytoplasmic p27kip1, RhoA activity and SAPK/JNK signalling. To this effect we observed a correlation between increased cytoplasmic p27kip1, increased RhoA protein levels, decreased RhoA-GTP levels and increased SAPK/JNK phosphorylation in blast phase CD34+ cells compared to chronic phase CD34+ cells.
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MESH Headings
- Anthracenes/pharmacology
- Antigens, CD34/genetics
- Antigens, CD34/metabolism
- Apoptosis
- Blast Crisis/genetics
- Blast Crisis/metabolism
- Blast Crisis/pathology
- Cyclin-Dependent Kinase Inhibitor p27/genetics
- Cyclin-Dependent Kinase Inhibitor p27/metabolism
- Cytoplasm/metabolism
- Cytoplasm/pathology
- Disease Progression
- Fusion Proteins, bcr-abl/genetics
- Fusion Proteins, bcr-abl/metabolism
- Gene Expression Regulation, Leukemic
- Guanosine Triphosphate/metabolism
- Humans
- K562 Cells
- Leukemia, Myeloid, Chronic-Phase/genetics
- Leukemia, Myeloid, Chronic-Phase/metabolism
- Leukemia, Myeloid, Chronic-Phase/pathology
- Lymphocytes/metabolism
- Lymphocytes/pathology
- MAP Kinase Kinase 4/antagonists & inhibitors
- MAP Kinase Kinase 4/genetics
- MAP Kinase Kinase 4/metabolism
- Phosphorylation/drug effects
- Primary Cell Culture
- Protein Kinase Inhibitors/pharmacology
- Signal Transduction
- rhoA GTP-Binding Protein/genetics
- rhoA GTP-Binding Protein/metabolism
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Affiliation(s)
- Anita Roy
- Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, West Bengal, India
| | - Lakshmishri Lahiry
- Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, West Bengal, India
| | - Debasis Banerjee
- Department of Haematology, Ramkrishna Mission Seva Pratisthan, Kolkata, West Bengal, India
| | - Malay Ghosh
- Department of Haematology, N R S Medical College and Hospital, Kolkata, West Bengal, India
| | - Subrata Banerjee
- Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, West Bengal, India
- * E-mail:
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12
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Kubiczkova L, Sedlarikova L, Hajek R, Sevcikova S. TGF-β - an excellent servant but a bad master. J Transl Med 2012; 10:183. [PMID: 22943793 PMCID: PMC3494542 DOI: 10.1186/1479-5876-10-183] [Citation(s) in RCA: 351] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 08/28/2012] [Indexed: 12/13/2022] Open
Abstract
The transforming growth factor (TGF-β) family of growth factors controls an immense number of cellular responses and figures prominently in development and homeostasis of most human tissues. Work over the past decades has revealed significant insight into the TGF-β signal transduction network, such as activation of serine/threonine receptors through ligand binding, activation of SMAD proteins through phosphorylation, regulation of target genes expression in association with DNA-binding partners and regulation of SMAD activity and degradation. Disruption of the TGF-β pathway has been implicated in many human diseases, including solid and hematopoietic tumors. As a potent inhibitor of cell proliferation, TGF-β acts as a tumor suppressor; however in tumor cells, TGF-β looses anti-proliferative response and become an oncogenic factor. This article reviews current understanding of TGF-β signaling and different mechanisms that lead to its impairment in various solid tumors and hematological malignancies.
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Affiliation(s)
- Lenka Kubiczkova
- Babak Myeloma Group, Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, 625 00, Czech Republic
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13
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The Blk pathway functions as a tumor suppressor in chronic myeloid leukemia stem cells. Nat Genet 2012; 44:861-71. [PMID: 22797726 PMCID: PMC3408839 DOI: 10.1038/ng.2350] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 06/15/2012] [Indexed: 12/18/2022]
Abstract
A therapeutic strategy for treating cancer is to target and eradicate cancer stem cells (CSCs) without harming their normal stem cell counterparts. The success of this approach relies on identification of molecular pathways that selectively regulate CSC function. Using BCR-ABL-induced chronic myeloid leukemia (CML) as a disease model for CSCs, we show that BCR-ABL down-regulates the B lymphoid kinase (Blk) gene through c-Myc in leukemia stem cells (LSCs) in CML mice and that Blk functions as a tumor suppressor in LSCs but does not affect normal hematopoietic stem cells (HSCs) or hematopoiesis. Blk suppresses LSC function through a pathway involving an upstream regulator, Pax5, and a downstream effector, p27. Inhibition of this Blk pathway accelerates CML development, whereas increased activity of the Blk pathway delays CML development. Blk also suppresses human CML stem cells. Our results demonstrate the feasibility of selectively targeting LSCs, an approach that should be applicable to other cancers.
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14
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Gómez-Casares MT, García-Alegria E, López-Jorge CE, Ferrándiz N, Blanco R, Alvarez S, Vaqué JP, Bretones G, Caraballo JM, Sánchez-Bailón P, Delgado MD, Martín-Perez J, Cigudosa JC, León J. MYC antagonizes the differentiation induced by imatinib in chronic myeloid leukemia cells through downregulation of p27(KIP1.). Oncogene 2012; 32:2239-46. [PMID: 22710719 DOI: 10.1038/onc.2012.246] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chronic myeloid leukemia (CML) progresses from a chronic to a blastic phase where the leukemic cells are proliferative and undifferentiated. The CML is nowadays successfully treated with BCR-ABL kinase inhibitors as imatinib and dasatinib. In the CML-derived K562 cell line, low concentrations of imatinib induce proliferative arrest and erythroid differentiation. We found that imatinib upregulated the cell cycle inhibitor p27(KIP1) (p27) in a time- and -concentration dependent manner, and that the extent of imatinib-mediated differentiation was severely decreased in cells with depleted p27. MYC (c-Myc) is a transcription factor frequently deregulated in human cancer. MYC is overexpressed in untreated CML and is associated to poor response to imatinib. Using K562 sublines with conditional MYC expression (induced by Zn(2+) or activated by 4-hydroxy-tamoxifen) we show that MYC prevented the erythroid differentiation induced by imatinib and dasatinib. The differentiation inhibition is not due to increased proliferation of MYC-expressing clones or enhanced apoptosis of differentiated cells. As p27 overexpression is reported to induce erythroid differentiation in K562, we explored the effect of MYC on imatinib-dependent induction of p27. We show that MYC abrogated the imatinib-induced upregulation of p27 concomitantly with the differentiation inhibition, suggesting that MYC inhibits differentiation by antagonizing the imatinib-mediated upregulation of p27. This effect occurs mainly by p27 protein destabilization. This was in part due to MYC-dependent induction of SKP2, a component of the ubiquitin ligase complex that targets p27 for degradation. The results suggest that, although MYC deregulation does not directly confer resistance to imatinib, it might be a factor that contributes to progression of CML through the inhibition of differentiation.
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Affiliation(s)
- M T Gómez-Casares
- Servicio de Hematología and Unidad de Investigación, Hospital Universitario Dr Negrín, Las Palmas, Spain
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15
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Yang KT, Wang MC, Chen JY, Hsu MC, Hung WC. Bcr-Abl oncogene stimulates Jab1 expression via cooperative interaction of β-catenin and STAT1 in chronic myeloid leukemia cells. J Cell Physiol 2011; 226:2849-56. [PMID: 21935931 DOI: 10.1002/jcp.22633] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Jab1, a co-activator of AP-1 transcription factor and the fifth subunit of the COP9 signalosome, mediates degradation of the tumor suppressor p53 and p27(Kip1) and functions as a tumor promoter in different types of human cancer. In this study, we show that inhibition of Bcr-Abl oncogene by imatinib induces down-regulation of Jab1 in Bcr-Abl-positive K562, Ku812, and MEG01 leukemia cells suggesting Bcr-Abl may regulate Jab1 expression. Promoter deletion and mutation analysis indicate the Tcf-4/β-catenin and STAT1 binding sites located between the -405/-223 region of the human Jab1 promoter are important for the activation of Jab1 by Bcr-Abl. Double mutation of these two sites reverses the inhibitory effect of imatinib. Chromatin immunoprecipitation assay verifies the binding of β-catenin and STAT1 to human Jab1 promoter. Ectopic expression of dominant-negative Tcf-4 mutant significantly attenuates Jab1 expression while over-expression of β-catenin and STAT1 cooperatively up-regulates Jab1 promoter activity and mRNA expression. Our results also demonstrate that the AKT signaling pathway is involved in the regulation of Jab1 by Bcr-Abl because the AKT inhibitor LY294002 but not the ERK inhibitor PD98059 reduces Jab1 promoter activity and mRNA expression. Taken together, our results suggest that Bcr-Abl stimulates Jab1 expression via the cooperative interaction of β-catenin and STAT1 in leukemia cells.
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Affiliation(s)
- Kuei-Ting Yang
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan
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16
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Santos FPS, Kantarjian H, McConkey D, O'Brien S, Faderl S, Borthakur G, Ferrajoli A, Wright J, Cortes J. Pilot study of bortezomib for patients with imatinib-refractory chronic myeloid leukemia in chronic or accelerated phase. CLINICAL LYMPHOMA, MYELOMA & LEUKEMIA 2011; 11:355-60. [PMID: 21816374 PMCID: PMC4405186 DOI: 10.1016/j.clml.2011.06.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 12/21/2010] [Indexed: 10/17/2022]
Abstract
BACKGROUND Proteasome inhibitors are anticancer compounds that disrupt the proteolytic activity of the proteasome and lead to tumor cell growth arrest and apoptosis. Bortezomib is a proteasome inhibitor that is currently approved for use in multiple myeloma (MM) and mantle-cell lymphoma. It induces apoptosis of chronic myeloid leukemia (CML) cells in vitro, but the activity of bortezomib in patients with imatinib-resistant CML is unknown. METHODS We conducted a pilot trial to evaluate the activity of single-agent bortezomib in CML. Seven patients with imatinib-refractory CML were treated with bortezomib at a dose of 1.5 mg/m2 on days 1, 4, 8, and 11 every 3 weeks. RESULTS The median number of cycles received was 2. No patient had a hematologic or cytogenetic response. Three patients had a temporary decrease in basophil counts associated with therapy with bortezomib. Six patients experienced grade 3/4 nonhematologic toxicities. CONCLUSION Bortezomib had minimal efficacy and considerable toxicity in patients with imatinib-refractory CML. Further studies should focus on alternative approaches to using proteasome inhibitors in the treatment of CML, such as in combination with tyrosine kinase inhibitors (TKIs) or as a strategy to eradicate leukemic stem cells.
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Affiliation(s)
- Fabio P S Santos
- Department of Leukemia, University of Texas - M. D. Anderson Cancer Center, Houston, Texas, USA
| | - Hagop Kantarjian
- Department of Leukemia, University of Texas - M. D. Anderson Cancer Center, Houston, Texas, USA
| | - David McConkey
- Department of Cancer Biology, University of Texas – M.D. Anderson Cancer, Houston, Texas, USA
| | - Susan O'Brien
- Department of Leukemia, University of Texas - M. D. Anderson Cancer Center, Houston, Texas, USA
| | - Stefan Faderl
- Department of Leukemia, University of Texas - M. D. Anderson Cancer Center, Houston, Texas, USA
| | - Gautam Borthakur
- Department of Leukemia, University of Texas - M. D. Anderson Cancer Center, Houston, Texas, USA
| | - Alessandra Ferrajoli
- Department of Leukemia, University of Texas - M. D. Anderson Cancer Center, Houston, Texas, USA
| | - John Wright
- Cancer Therapy Evaluation Program, National Cancer Institute, Bethesda, Maryland, USA
| | - Jorge Cortes
- Department of Leukemia, University of Texas - M. D. Anderson Cancer Center, Houston, Texas, USA
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17
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Warr MR, Pietras EM, Passegué E. Mechanisms controlling hematopoietic stem cell functions during normal hematopoiesis and hematological malignancies. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 3:681-701. [PMID: 21412991 DOI: 10.1002/wsbm.145] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Hematopoiesis, the process by which all mature blood cells are generated from multipotent hematopoietic stem cells (HSCs), is a finely tuned balancing act in which HSCs must constantly decide between different cell fates: to proliferate, to self-renew or differentiate, to stay quiescent in the bone marrow niche or migrate to the periphery, to live or die. These fates are regulated by a complex interplay between cell-extrinsic cues and cell-intrinsic regulatory pathways whose function is to maintain a homeostatic balance between HSC self-renewal and life-long replenishment of lost blood cells. Improper regulation of these competing cellular programs can transform HSCs and progenitor cells into disease-initiating leukemic stem cells (LSCs). Strikingly, many of the mechanisms required for maintenance of normal HSC fate decisions are equally critical for the aberrant functions of LSCs. Because of the inherent complexities of these molecular mechanisms, a systematic approach to understanding the regulatory networks underlying HSC self-renewal is critical for uncovering the similarities and differences between HSCs and LSCs. In this review, we focus on recent developments in elucidating the regulatory networks governing normal HSC self-renewal programs and their implications for leukemic transformation. We describe the current technical and methodological limitations in isolating and characterizing HSCs and LSCs, and the emerging approaches that may afford a better understanding of the regulation of normal and leukemic hematopoiesis. Finally, we discuss how such basic mechanistic information may be of use for the design of novel therapies that will selectively reprogram and/or eliminate LSCs.
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Affiliation(s)
- Matthew R Warr
- The Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, Division of Hematology/Oncology, Department of Medicine, University of California San Francisco, San Francisco, CA, USA
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18
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Borriello A, Caldarelli I, Bencivenga D, Cucciolla V, Oliva A, Usala E, Danise P, Ronzoni L, Perrotta S, Della Ragione F. p57 Kip2 is a downstream effector of BCR–ABL kinase inhibitors in chronic myelogenous leukemia cells. Carcinogenesis 2010; 32:10-8. [DOI: 10.1093/carcin/bgq211] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Role of BCR-ABL-Y177-mediated p27kip1 phosphorylation and cytoplasmic localization in enhanced proliferation of chronic myeloid leukemia progenitors. Leukemia 2010; 24:779-87. [PMID: 20200561 PMCID: PMC2854856 DOI: 10.1038/leu.2010.24] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In chronic myelogenous leukemia (CML) hematopoietic stem cell transformation leads to increased proliferation of malignant myeloid progenitors. The cyclin-dependent kinase inhibitor p27kip1 (p27) is a critical negative regulator of hematopoietic progenitor proliferation and pool size that is deregulated in BCR-ABL expressing cell lines. However, cell-context specific regulation of p27 in primary human CML progenitors and its contribution to CML progenitor expansion remain unclear. Here we investigated p27 regulation and function in (1) CD34+ cells from CML patients and (2) human CD34+ cells ectopically expressing the BCR-ABL gene following retrovirus transduction. We found that p27 levels are increased in CML CD34+ cells related to a BCR-ABL dependent increase in p27 protein translation. However p27 was relocated to the cytoplasm in CML progenitors and nuclear p27 levels were reduced, allowing increased cell cycling and expansion in culture. Cytoplasmic relocation of p27 in CML progenitors was related to signaling through BCR-ABL Y177, activation of the AKT kinase and phosphorylation of p27 on Thr-157 (T157). Expression of a mutant p27 that cannot be phosphorylated on T157 significant inhibited CML progenitor proliferation. These studies demonstrate the importance of BCR-ABL-Y177-AKT mediated p27 phosphorylation in altered p27 localization and enhanced proliferation and expansion of primary CML progenitors.
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20
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Skorta I, Oren M, Markwardt C, Gutekunst M, Aulitzky WE, van der Kuip H. Imatinib mesylate induces cisplatin hypersensitivity in Bcr-Abl+ cells by differential modulation of p53 transcriptional and proapoptotic activity. Cancer Res 2010; 69:9337-45. [PMID: 19934315 DOI: 10.1158/0008-5472.can-09-0548] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Imatinib is highly effective in inducing remission in chronic myelogenous leukemia (CML). However, complete eradication of the malignant clone by imatinib is rare. We investigated the efficacy of combining imatinib with cisplatin. Inhibition of Bcr-Abl by imatinib induced a hypersensitive phenotype both in Bcr-Abl(+) cell lines and in CD34(+) cells from CML patients. Importantly, cisplatin sensitivity of leukemic cells harboring an inactive Bcr-Abl greatly exceeded that of Bcr-Abl(-) parental cells. The cisplatin response of Bcr-Abl(+) cells treated with imatinib was characterized by an impaired G(2)-M arrest and by rapid induction of mitochondrial cell death after the first passage through G(2). Imatinib abrogated ATM activation on cisplatin selectively in Bcr-Abl(+) cells. As a consequence, phosphorylation of p53 on Ser(15) and its activity as a transcription factor was significantly diminished. Furthermore, p53 accumulated predominantly in the cytoplasm in Bcr-Abl(+) cells treated with imatinib and cisplatin. Silencing of p53 significantly reduced sensitivity to cisplatin in imatinib-treated Bcr-Abl(+) cells, indicating that p53 retains its proapoptotic activity. Simultaneous downregulation of Bcl-x(L) was an additional requirement for cisplatin hypersensitivity, as p53-dependent cell death could be antagonized by exogenous Bcl-x(L). We conclude that imatinib sensitizes Bcr-Abl(+) cells to cisplatin by simultaneous inhibition of p53 transactivation, induction of p53 accumulation predominantly in the cytoplasm, and reduction of Bcl-x(L).
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Affiliation(s)
- Ioanna Skorta
- Dr Margarete-Fischer-Bosch Institute of Clinical Pharmacology and University of Tuebingen, Stuttgart, Germany
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21
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Jabbour E, El Ahdab S, Cortes J, Kantarjian H. Nilotinib: a novel Bcr-Abl tyrosine kinase inhibitor for the treatment of leukemias. Expert Opin Investig Drugs 2008; 17:1127-36. [PMID: 18549348 DOI: 10.1517/13543784.17.7.1127] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The successful introduction of the tyrosine kinase inhibitors has initiated a new era in the management of chronic myeloid leukemia (CML). Imatinib mesilate therapy has significantly improved the prognosis of CML. A minority of patients in chronic-phase CML--and more patients in advanced phases--are resistant to imatinib, or develop resistance during treatment. This is attributed, in 40-50% of cases, to the development of mutations in the Bcr-Abl tyrosine kinase domain that impair imatinib binding. Nilotinib (Tasigna) is a novel potent selective oral kinase inhibitor. Preclinical and clinical investigations demonstrate that nilotinib effectively overcomes imatinib resistance, and has induced high rates of hematologic and cytogenetic responses in CML post imatinib failure.
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Affiliation(s)
- Elias Jabbour
- The University of Texas, MD Anderson Cancer Center, Department of Leukemia, Unit 428, 1515 Holcombe Blvd, Houston, TX 77030, USA.
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22
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Abstract
BCR-ABL is proposed to impair cell-cycle control by disabling p27, a tumor suppressor that inhibits cyclin-dependent kinases. We show that in cell lines p27 expression is inversely correlated with expression of SKP2, the F-box protein of SCF(SKP2) (SKP1/Cul1/F-box), the E3 ubiquitin ligase that promotes proteasomal degradation of p27. Inhibition of BCR-ABL kinase causes G(1) arrest, down-regulation of SKP2, and accumulation of p27. Ectopic expression of wild-type SKP2, but not a mutant unable to recognize p27, partially rescues cell-cycle progression. A similar regulation pattern is seen in cell lines transformed by FLT3-ITD, JAK2(V617F), and TEL-PDGFRbeta, suggesting that the SKP2/p27 conduit may be a universal target for leukemogenic tyrosine kinases. Mice that received transplants of BCR-ABL-infected SKP2(-/-) marrow developed a myeloproliferative syndrome but survival was significantly prolonged compared with recipients of BCR-ABL-expressing SKP2(+/+) marrow. SKP2(-/-) leukemic cells demonstrated higher levels of nuclear p27 than SKP2(+/+) counterparts, suggesting that the attenuation of leukemogenesis depends on increased p27 expression. Our data identify SKP2 as a crucial mediator of BCR-ABL-induced leukemogenesis and provide the first in vivo evidence that SKP2 promotes oncogenesis. Hence, stabilization of p27 by inhibiting its recognition by SCF(SKP2) may be therapeutically useful.
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23
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Loss of Bcl-x in Ph+ B-ALL increases cellular proliferation and does not inhibit leukemogenesis. Blood 2008; 111:3760-9. [PMID: 18216295 DOI: 10.1182/blood-2007-08-108803] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The kinase inhibitors imatinib mesylate and dasatinib are the preferred treatment for Philadelphia chromosome-positive (Ph+) leukemias, and they are highly successful in the chronic phase of chronic myeloid leukemia (CML). However, they are not efficient in Ph+ B-cell acute lymphoblastic leukemia (B-ALL). Ph+ leukemia cells are highly resistant to apoptosis, and evidence from cell lines and primary cells suggest Bcl-xL as a critical mediator of resistance to apoptosis: however, this concept has never been rigorously tested in an animal model. To clarify the role of Bcl-xL in Ph+ B-ALL, we generated 2 mouse models. In the first model, Ph+ B-ALL and loss of Bcl-xL expression are coinduced; in the second model, leukemia is induced with expression of Bcl-xL protein well above the levels found in wild-type lymphoblasts. Deletion of Bcl-xL did not inhibit leukemogenesis or affect apoptosis, but increased cellular proliferation. Consistent with this result, overexpression of Bcl-xL led to decreased cellular proliferation. These models reveal an unexpected role for Bcl-xL in cell-cycle entry and the proliferation of tumor cells.
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Abstract
OBJECTIVE To characterize the effect, if any, of imatinib mesylate, an inhibitor of abl tyrosine kinase used in the treatment of chronic myeloid leukemia, on type 2 diabetes. METHODS The centralized pharmacy database was used to identify all patients who had received imatinib at the Mayo Clinic in Rochester, Minnesota, during a 5-year period. The electronic medical records were subsequently reviewed to identify which of these patients had type 2 diabetes. In addition, relevant biochemical data, prior to, during, and after imatinib treatment, were abstracted from the electronic laboratory database and medical records. RESULTS At the Mayo Clinic in Rochester, Minnesota, a total of 164 patients received imatinib during the period of study (1999 to 2004). Of these 164 patients, 7 had preexisting type 2 diabetes, and diabetes developed in 2 patients during treatment with imatinib. Despite 2 previous reports of improvement in glycemic control with use of imatinib in patients with type 2 diabetes, no net effect on glycemic control or diabetes therapy was noted in our study cohort. CONCLUSION On the basis of our current study, it seems unlikely that imatinib substantially affects glycemic control in patients with type 2 diabetes.
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Affiliation(s)
- David Dingli
- Division of Hematology, Department of Internal Medicine, Mayo Clinic College of Medicine, 200 First Street Southwest, Rochester, Minnesota 55905, USA
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25
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Grimmler M, Wang Y, Mund T, Cilensek Z, Keidel EM, Waddell MB, Jäkel H, Kullmann M, Kriwacki RW, Hengst L. Cdk-inhibitory activity and stability of p27Kip1 are directly regulated by oncogenic tyrosine kinases. Cell 2007; 128:269-80. [PMID: 17254966 DOI: 10.1016/j.cell.2006.11.047] [Citation(s) in RCA: 266] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Revised: 09/13/2006] [Accepted: 11/20/2006] [Indexed: 10/23/2022]
Abstract
p27Kip1 controls cell proliferation by binding to and regulating the activity of cyclin-dependent kinases (Cdks). Here we show that Cdk inhibition and p27 stability are regulated through direct phosphorylation by tyrosine kinases. A conserved tyrosine residue (Y88) in the Cdk-binding domain of p27 can be phosphorylated by the Src-family kinase Lyn and the oncogene product BCR-ABL. Y88 phosphorylation does not prevent p27 binding to cyclin A/Cdk2. Instead, it causes phosphorylated Y88 and the entire inhibitory 3(10)-helix of p27 to be ejected from the Cdk2 active site, thus restoring partial Cdk activity. Importantly, this allows Y88-phosphorylated p27 to be efficiently phosphorylated on threonine 187 by Cdk2 which in turn promotes its SCF-Skp2-dependent degradation. This direct link between transforming tyrosine kinases and p27 may provide an explanation for Cdk kinase activities observed in p27 complexes and for premature p27 elimination in cells that have been transformed by activated tyrosine kinases.
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Affiliation(s)
- Matthias Grimmler
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
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26
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Li S. Src kinase signaling in leukaemia. Int J Biochem Cell Biol 2007; 39:1483-8. [PMID: 17350876 PMCID: PMC2063586 DOI: 10.1016/j.biocel.2007.01.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 01/23/2007] [Accepted: 01/25/2007] [Indexed: 01/28/2023]
Abstract
Role of Src kinases in acute lymphoblastic leukaemia has been recently demonstrated in leukaemia mouse model. Retained activation of Src kinases by the BCR-ABL oncoprotein in leukaemic cells following inhibition of BCR-ABL kinase activity by imatinib indicates that Src activation by BCR-ABL is independent of BCR-ABL kinase activity and provides an explanation for reduced effectiveness of the BCR-ABL kinase activity inhibitors in Philadelphia chromosome-positive acute lymphoblastic leukaemia. Simultaneous inhibition of kinase activity of both BCR-ABL and Src kinases results in long-term survival of mice with acute lymphoblastic leukaemia. Leukaemic stem cells exist in acute lymphoblastic leukaemia, and complete eradication of this group of cells would provide a curative therapy for this disease.
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Affiliation(s)
- Shaoguang Li
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA.
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27
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Li X, Xu YB, Wang Q, Lu Y, Zheng Y, Wang YC, Lübbert M, Zhao KW, Chen GQ. Leukemogenic AML1-ETO fusion protein upregulates expression of connexin 43: the role in AML 1-ETO-induced growth arrest in leukemic cells. J Cell Physiol 2006; 208:594-601. [PMID: 16741927 DOI: 10.1002/jcp.20695] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
AML1-ETO, a fusion protein generated by the chromosomal translocation t(8;21), is frequently associated with acute myeloid leukemia (AML). In addition to blocking differentiation, AML1-ETO is also shown to induce growth arrest in AML cells, which is unfavorable for leukemogenesis harboring the t(8;21) translocation. However, its precise mechanism is still unclear. Here we provide the first demonstration that the conditional expression of AML1-ETO by the ecdysone-inducible system dramatically increases the expression of connexin 43 (CX43), together with growth arrest at G1 phase in leukemic U937 cells. We also show that the CX43 induction inhibits the proliferation of U937 cells at G1 phase, while the suppression of CX43 expression by small interfering RNA (siRNA) effectively overcomes the growth-inhibitory effect of AML1 -ETO in leukemic cells. Furthermore, either AML1-ETO or CX43 induction elevates cell-cycle negative regulator P27(kip1) protein by inhibiting its degradation, which is antagonized by siRNA against CX43. Taken together, our data indicate that CX43 plays a role in AML1-ETO-induced growth arrest possibly through the accumulation of P27(kip1) protein. The potential mutation or/and epigenetic alterations of CX43 and its related gene(s) deserve to be explored in AML1-ETO-positive AML patients.
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MESH Headings
- Base Sequence
- Cell Cycle
- Cell Line, Tumor
- Chromosomes, Human, Pair 21
- Chromosomes, Human, Pair 8
- Connexin 43/genetics
- Core Binding Factor Alpha 2 Subunit/genetics
- Core Binding Factor Alpha 2 Subunit/metabolism
- DNA Primers
- Humans
- Leukemia, Myeloid, Acute
- Molecular Sequence Data
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- RNA, Small Interfering
- RUNX1 Translocation Partner 1 Protein
- Recombinant Fusion Proteins/pharmacology
- Reverse Transcriptase Polymerase Chain Reaction
- Translocation, Genetic
- U937 Cells
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Affiliation(s)
- Xi Li
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Rui-Jin Hospital, Shanghai Jiao Tong University School of Medicine (SJTU-SM), Shanghai, China
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28
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The clinical challenge of imatinib resistance in chronic myeloid leukemia: emerging strategies with new targeted agents. Target Oncol 2006. [DOI: 10.1007/s11523-006-0032-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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29
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Fiskus W, Pranpat M, Bali P, Balasis M, Kumaraswamy S, Boyapalle S, Rocha K, Wu J, Giles F, Manley PW, Atadja P, Bhalla K. Combined effects of novel tyrosine kinase inhibitor AMN107 and histone deacetylase inhibitor LBH589 against Bcr-Abl-expressing human leukemia cells. Blood 2006; 108:645-52. [PMID: 16537804 DOI: 10.1182/blood-2005-11-4639] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
AMN107 (Novartis Pharmaceuticals, Basel, Switzerland) has potent in vitro and in vivo activity against the unmutated and most common mutant forms of Bcr-Abl. Treatment with the histone deacetylase inhibitor LBH589 (Novartis) depletes Bcr-Abl levels. We determined the effects of AMN107 and/or LBH589 in Bcr-Abl-expressing human K562 and LAMA-84 cells, as well as in primary chronic myelogenous leukemia (CML) cells. AMN107 was more potent than imatinib mesylate (IM) in inhibiting Bcr-Abl tyrosine kinase (TK) activity and attenuating p-STAT5, p-AKT, Bcl-x(L), and c-Myc levels in K562 and LAMA-84 cells. Cotreatment with LBH589 and AMN107 exerted synergistic apoptotic effects with more attenuation of p-STAT5, p-ERK1/2, c-Myc, and Bcl-x(L) and increases in p27 and Bim levels. LBH589 attenuated Bcr-Abl levels and induced apoptosis of mouse pro-B BaF3 cells containing ectopic expression of Bcr-Abl or the IM-resistant, point-mutant Bcr-AblT315I and Bcr-AblE255K. Treatment with LBH589 also depleted Bcr-Abl levels and induced apoptosis of IM-resistant primary human CML cells, including those with expression of Bcr-AblT315I. As compared with either agent alone, cotreatment with AMN107 and LBH589 induced more loss of cell viability of primary IM-resistant CML cells. Thus, cotreatment with LBH589 and AMN107 is active against cultured or primary IM-resistant CML cells, including those with expression of Bcr-AblT315I.
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MESH Headings
- Animals
- Apoptosis/drug effects
- Benzamides
- Cell Line, Tumor
- Drug Resistance, Neoplasm
- Drug Synergism
- Fusion Proteins, bcr-abl/antagonists & inhibitors
- Histone Deacetylase Inhibitors
- Humans
- Hydroxamic Acids/pharmacology
- Imatinib Mesylate
- Indoles
- Leukemia/drug therapy
- Leukemia/pathology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Mice
- Panobinostat
- Piperazines/pharmacology
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Pyrimidines/pharmacology
- Tumor Cells, Cultured
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Affiliation(s)
- Warren Fiskus
- Department of Interdisciplinary Oncology, H. Lee Moffitt Cancer Center, Tampa, FL 33612, USA
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Raicević N, Mladenović A, Perović M, Miljković D, Trajković V. The Mechanisms of 6-Hydroxydopamine-Induced Astrocyte Death. Ann N Y Acad Sci 2006; 1048:400-5. [PMID: 16154962 DOI: 10.1196/annals.1342.049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Treatment with 6-hydroxydopamine significantly reduced the viability of cultured rat primary astrocytes, rat astrocytoma cell line C6, and human astrocytoma cell line U251. 6-Hydroxydopamine-treated astrocytes exhibited altered nuclear morphology, DNA fragmentation, and reduced intracellular esterase activity, which indicated apoptotic cell death. Astrocytes were protected by neutralization of 6-hydroxydopamine autooxidation products H(2)O(2), O(2)(*-), and (*)OH, but not by cell-derived or chemically generated anti-apoptotic free radical nitric oxide. Finally, 6-hydroxydopamine activated extracellular signal-regulated kinase in astrocytes and selective inhibitor of extracellular signal-regulated kinase activation partially prevented astrocyte death. Taken together, these data indicate that 6-hydroxydopamine-triggered oxidative stress induces extracellular signal-regulated kinase-dependent apoptotic death of astrocytes.
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Affiliation(s)
- Nevena Raicević
- Institute for Biological Research Sinisa Stanković, Belgrade, Serbia and Montenegro.
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Sengupta A, Banerjee D, Chandra S, Banerjee S. Gene therapy for BCR-ABL+ human CML with dual phosphorylation resistant p27Kip1 and stable RNA interference using an EBV vector. J Gene Med 2006; 8:1251-61. [PMID: 16952195 DOI: 10.1002/jgm.959] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND BCR-ABL-mediated chronic myelogenous leukemia (CML) CD34(+) cell proliferation mostly depends on the nucleo-cytoplasmic ratio of the cyclin-dependent kinase inhibitor p27. The ubiquitin-ligase SCF(Skp2) promotes degradation of phosphorylated p27 at T187 in the nucleus, resulting in G1/S progression of the cells. On the other hand, phosphatidylinositol-3-kinase (PI3K)-directed T157 nuclear localization signal (NLS) phosphorylation results in cytoplasmic sequestration of p27, leading to abnormal integrin-mediated proliferation of CD34(+) CML cells. METHODS We demonstrate the generation of an engineered Epstein-Barr virus (EBV) vector with a BAC backbone that has the unique capacity to carry doubly modified (DM) p27 (i.e. T187A, T157A p27) along with the BCR-ABL siRNA expression construct. The HSV-tk suicide gene has also been incorporated in the same vector, which promotes apoptosis in a BCR-ABL-independent pathway. RESULTS Expression of DM p27 markedly inhibits proliferation of BCR-ABL(+) primary human CML cells. Moreover, DM p27 strongly inhibits the growth of imatinib-resistant CML cells, compared to the T157A p27 (SM p27). The CML growth inhibition is found to be the result of significant G1/S arrest with concomitant increase in hypophosphorylated retinoblastoma (Rb). Moreover, the EBV vector mediated stable RNA interference induces apoptosis in K562 cells and reduces myeloid colony forming units. CONCLUSIONS We therefore propose a multi-gene delivery strategy for BCR-ABL(+) CML cells by targeting not only the fusion transcript, but also the downstream signaling, to overcome drug resistance in the acute phase of CML.
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MESH Headings
- Active Transport, Cell Nucleus
- Apoptosis/drug effects
- Benzamides
- Cell Proliferation/drug effects
- Cyclin-Dependent Kinase Inhibitor p27/genetics
- Cyclin-Dependent Kinase Inhibitor p27/metabolism
- Fusion Proteins, bcr-abl/antagonists & inhibitors
- G1 Phase
- Genes, Transgenic, Suicide
- Genetic Engineering
- Genetic Therapy/methods
- Genetic Vectors/chemical synthesis
- Herpesvirus 4, Human/genetics
- Humans
- Imatinib Mesylate
- K562 Cells
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/therapy
- Models, Biological
- Phosphorylation
- Piperazines/pharmacology
- Point Mutation
- Pyrimidines/pharmacology
- RNA Interference
- RNA, Small Interfering/chemical synthesis
- Retinoblastoma/metabolism
- S Phase
- Tumor Cells, Cultured
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Affiliation(s)
- Amitava Sengupta
- Structural Genomics Section & Biophysics Division, Saha Institute of Nuclear Physics, Kolkata 700 064, India
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32
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Moehring A, Wohlbold L, Aulitzky WE, van der Kuip H. Role of poly(ADP-ribose) polymerase activity in imatinib mesylate-induced cell death. Cell Death Differ 2005; 12:627-36. [PMID: 15818402 DOI: 10.1038/sj.cdd.4401608] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Imatinib targets Bcr-Abl, the causative event of chronic myelogenous leukemia (CML), and addresses leukemic cells to growth arrest and cell death. The exact mechanisms responsible for imatinib-induced cell death are still unclear. We investigated the role of poly(ADP-ribose) polymerase (PARP) activity in imatinib-induced cell death in Bcr-Abl-positive cells. Imatinib leads to a rapid increase of poly(ADP-ribosyl)ation (PAR) preceding loss of integrity of mitochondrial membrane and DNA fragmentation. The effect of imatinib on PAR can be mimicked by inhibition of phosphatidylinositol 3-kinase (PI3-K) implicating a central role of the PI3-K pathway in Bcr-Abl-mediated inhibition of PAR. Importantly, inhibition of PAR in imatinib-treated cells partially prevented cell death to an extent comparable to that observed after caspase inhibition. Simultaneous blockade of both caspases and PAR revealed additive cytoprotective effects indicating that both pathways function in parallel. In conclusion, our results suggest that in addition to the well-documented caspase-dependent pathway, imatinib also induces a PARP-mediated death process.
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Affiliation(s)
- A Moehring
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Auerbachstr. 112, Stuttgart, Germany
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33
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Geay JF, Buet D, Zhang Y, Foudi A, Jarrier P, Berthebaud M, Turhan AG, Vainchenker W, Louache F. p210BCR-ABL inhibits SDF-1 chemotactic response via alteration of CXCR4 signaling and down-regulation of CXCR4 expression. Cancer Res 2005; 65:2676-83. [PMID: 15805265 DOI: 10.1158/0008-5472.can-04-2152] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
It has been shown that p210(BCR-ABL) significantly impairs CXCR4 signaling. We report here that the migratory response to SDF-1 was profoundly altered in blast crisis, whereas chronic-phase CD34(+) cells migrated normally to this chemokine. This migratory defect was associated with a low CXCR4 membrane expression. In vitro STI-571 treatment of CD34(+) cells from patients in blast crisis markedly increased the CXCR4 transcript and CXCR4 membrane expression. Because p210(BCR-ABL) frequently increases with disease progression, we determined the effects of high and low p210(BCR-ABL) expression on CXCR4 protein in the granulocyte macrophage colony-stimulating factor-dependent human cell line MO7e. p210(BCR-ABL) expression distinctly alters CXCR4 protein through two different mechanisms depending on its expression level. At low expression, a signaling defect was detected with no modification of CXCR4 expression. However, higher p210(BCR-ABL) expression induced a marked down-regulation of CXCR4 that is related to its decreased transcription. The effect of p210(BCR-ABL) required its tyrosine kinase activity. Collectively, these data indicate that p210(BCR-ABL) could affect CXCR4 by more than one mechanism and suggest that down-regulation of CXCR4 may have important implications in chronic myelogenous leukemia pathogenesis.
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MESH Headings
- Animals
- Antigens, CD34/biosynthesis
- Benzamides
- Blast Crisis
- Cell Line
- Chemokine CXCL12
- Chemokines, CXC/antagonists & inhibitors
- Chemokines, CXC/physiology
- Down-Regulation
- Fusion Proteins, bcr-abl/biosynthesis
- Fusion Proteins, bcr-abl/genetics
- Fusion Proteins, bcr-abl/metabolism
- Fusion Proteins, bcr-abl/physiology
- Hematopoietic Stem Cells/cytology
- Hematopoietic Stem Cells/metabolism
- Hematopoietic Stem Cells/physiology
- Humans
- Imatinib Mesylate
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Mice
- NIH 3T3 Cells
- Piperazines/pharmacology
- Pluripotent Stem Cells/cytology
- Pluripotent Stem Cells/metabolism
- Pluripotent Stem Cells/physiology
- Pyrimidines/pharmacology
- Receptors, CXCR4/antagonists & inhibitors
- Receptors, CXCR4/biosynthesis
- Receptors, CXCR4/physiology
- Signal Transduction
- Transcription, Genetic
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Affiliation(s)
- Jean-Francois Geay
- Institut National de la Sante et de la Recherche Medicale, Institut Gustave Roussy, Villejuif, France
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34
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Affiliation(s)
- A Krämer
- Medizinische Klinik V, Universität Heidelberg, Heidelberg, Germany.
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35
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Wang W, Yao LB, Liu XP, Feng Q, Shang ZC, Cao YX, Sun BZ. Effects of STI571 and p27 gene clone on proliferation and apoptosis of K562 cells. World J Gastroenterol 2005; 11:2130-5. [PMID: 15810079 PMCID: PMC4305782 DOI: 10.3748/wjg.v11.i14.2130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the combined effect of STI571 and p27 gene clone on the regulation of proliferation, cell cycle and apoptosis of K562 cell line.
METHODS: p27 gene was obtained by RT-PCR, and its sequence was approved to be correct. Then p27-pcDNA3.1 vector was constructed and transfected into K562 cell line. p27-pcDNA3.1-K562 cell clone was screened by G418 after transfection, p27 protein was identified by Western blot. MTT was used to detect the survival rate of the cell. Flow cytometry was used to detect cell cycle and apoptosis index.
RESULTS: The expression of p27 protein could be detected by Western blot in p27-pcDNA3.1-K562 cells. A strong inhibition of cell proliferation was observed in p27-pcDNA3.1 -K562 cells as compared with that of the control (pcDNA3.1 -K562 cells). The cells at G0/G1 phase were significantly increased, and cells at S phase were greatly declined. The apoptosis index was increased greatly after p27-pcDNA3.1-K562 cells were treated with STI571, and survival rate of the cell was markedly declined (0.35-0.58, P<0.05-0.048 vs STI571-K562 cell, 0.35-0.72, P<0.01-0.001 vs p27-K562 cell).
CONCLUSION: p27 and STI571 have a synergistic action on inhibition of proliferation and induction of apoptosis on K562 cells.
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Affiliation(s)
- Wei Wang
- Department of Hematology, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, Shaanxi Province, China
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36
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Kathrein KL, Lorenz R, Innes AM, Griffiths E, Winandy S. Ikaros induces quiescence and T-cell differentiation in a leukemia cell line. Mol Cell Biol 2005; 25:1645-54. [PMID: 15713624 PMCID: PMC549358 DOI: 10.1128/mcb.25.5.1645-1654.2005] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ikaros is a hematopoietic cell-specific zinc finger DNA binding protein that plays an important role in lymphocyte development. Genetic disruption of Ikaros results in T-cell transformation. Ikaros null mice develop leukemia with 100% penetrance. It has been hypothesized that Ikaros controls gene expression through its association with chromatin remodeling complexes. The development of leukemia in Ikaros null mice suggests that Ikaros has the characteristics of a tumor suppressor gene. In this report, we show that the introduction of Ikaros into an established mouse Ikaros null T leukemia cell line leads to growth arrest at the G0/G1 stage of the cell cycle. This arrest is associated with up-regulation of the cell cycle-dependent kinase inhibitor p27kip1, the induction of expression of T-cell differentiation markers, and a global and specific increase in histone H3 acetylation status. These studies provide strong evidence that Ikaros possesses the properties of a bona fide tumor suppressor gene for the T-cell lineage and offer insight into the mechanism of Ikaros's tumor suppressive activity.
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Affiliation(s)
- Katie L Kathrein
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, 320 E. Superior St., Morton 6-639, Chicago, IL 60611, USA
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37
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Tomoda K, Kato JY, Tatsumi E, Takahashi T, Matsuo Y, Yoneda-Kato N. The Jab1/COP9 signalosome subcomplex is a downstream mediator of Bcr-Abl kinase activity and facilitates cell-cycle progression. Blood 2005; 105:775-83. [PMID: 15353483 DOI: 10.1182/blood-2004-04-1242] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractJab1 is a multifunctional protein associated with the signaling pathway, cell-cycle regulation, and development, and acts as a key subunit of COP9 signalosome (CSN). Jab1 promotes degradation of the cyclin-dependent kinase inhibitor p27Kip1 by transportation from the nucleus to the cytoplasm. However, there has been no clear evidence for whether and how Jab1 contributes to malignant transformation in human cancers. Here we show that Bcr-Abl tyrosine kinase facilitates the down-regulation of p27 by modulating complex formation of Jab1/CSN through the mitogen-activated protein (MAP) kinase and phosphatidylinositol 3 (PI3) kinase signaling pathways. Nearly half of the chronic myelogenous leukemia cell lines and the murine hematopoietic precursor cells expressing Bcr-Abl exhibited a marked increase in the small loose Jab1 complex located in the cytoplasm. Inhibition of Bcr-Abl kinase by STI571 induced G1 arrest and caused a recovery of the p27 level with reduction of the small Jab1 complex from the cytoplasm. Either blockade of the MAP kinase and PI3 kinase pathways by specific inhibitors or Jab1 knockdown by small interfering RNA (siRNA) prevented p27 down-regulation as well as formation of the small complex. Thus, regulation of p27 via modulation of the Jab1 subcomplex is a novel mechanism whereby Bcr-Abl oncogenic signals accelerate abnormal cell proliferation.
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Affiliation(s)
- Kiichiro Tomoda
- Department of Animal Molecular Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan
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38
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Conti S, Guercini F, Iorio A. Low-Molecular-Weight Heparin and Cancer Survival: Review of the Literature and Pooled Analysis of 1,726 Patients Treated for at Least Three Months. PATHOPHYSIOLOGY OF HAEMOSTASIS AND THROMBOSIS 2004; 33:197-201. [PMID: 15583449 DOI: 10.1159/000081508] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Accepted: 07/26/2004] [Indexed: 11/19/2022]
Abstract
BACKGROUND Heparin has been the main subject of intensive investigation and clinical use because of its therapeutic anticoagulant properties. It also exhibits many other biological activities, and it was claimed that it shows a beneficial effect on cancer spreading. Searching for papers investigating the effect of low-molecular-weight heparin (LMWH) on cancer mortality we found clinical trials and meta-analyses which showed a reduction in the mortality rate in cancer patients. However, the biological rationale of this effect for a short treatment with LMWH remains unclear. We wanted to check if similar results were achieved in cancer patients treated with LMWH for a longer period of time. AIM To evaluate the effect on cancer mortality of a 3-month treatment with LMWH by performing a meta-analysis of published studies comparing LMWH and oral anticoagulants (OA) in the prevention of recurrent venous thromboembolism (VTE). MATERIALS AND METHODS Computerized searches of Medline and Embase were performed; clinical trials were also located through colleagues and hand scanning of meeting proceedings. Eligibility of the studies and extraction of data were performed by two authors using a standard form. The meta-analysis was performed assuming a fixed-effect model. RESULTS Eight studies were identified that fulfilled our predefined criteria for a total of 1,726 patients. After a mean of 8.6 months of follow-up, 327 patients had died of cancer, 160 in the LMWH group and 167 in the OA control group (OR 0.95, 95% CI 0.73-1.23; z = 0.42; p = 0.67). Considering cancer mortality in 948 cancer patients the figures were 160/472 in the LMWH group and 167/476 in the OA control group (OR 0.96, 95% CI 0.73-1.25; z = 0.33; p = 0.74). CONCLUSIONS In 1,726 patients randomized to receive a long-term course of at least 3 months of LMWH or OA for the treatment of VTE, no effect on cancer mortality was found.
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Affiliation(s)
- Serenella Conti
- Sezione di Medicina Interna e Cardiovascolare, Università di Perugia, Perugia, Italy
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39
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Melo JV, Deininger MWN. Biology of chronic myelogenous leukemia--signaling pathways of initiation and transformation. Hematol Oncol Clin North Am 2004; 18:545-68, vii-viii. [PMID: 15271392 DOI: 10.1016/j.hoc.2004.03.008] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Chronic myeloid leukemia (CML) is caused by the Bcr-Abl oncoprotein,the product of the t(9;22) chromosomal translocation that generates the Philadelphia chromosome. Different disease phenotypes are associated with each of the three Bcr-Abl isoforms: p190Bcr-Abl, p210Bcr-Abl, and p230Bcr-Abl all of which have a constitutively activated tyrosine kinase. Mechanisms associated with malignant transformation include altered cellular adhesion, activation of mitogenic signaling pathways, inhibition of apoptosis, and proteasomal degradation of physiologically important cellular proteins.CML is subject to an inexorable progression from an "indolent" chronic phase to a terminal blast crisis. Disease progression is presumed to be associated with the phenomenon of genomic instability.
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MESH Headings
- Cell Transformation, Neoplastic/genetics
- Fusion Proteins, bcr-abl/genetics
- Fusion Proteins, bcr-abl/metabolism
- Fusion Proteins, bcr-abl/physiology
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/etiology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Oncogene Proteins/metabolism
- Oncogene Proteins/physiology
- Signal Transduction/genetics
- Translocation, Genetic
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Affiliation(s)
- Junia V Melo
- Department of Haematology, Imperial College, London & Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
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40
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Yoshida C, Melo JV. Biology of Chronic Myeloid Leukemia and Possible Therapeutic Approaches to Imatinib-Resistant Disease. Int J Hematol 2004; 79:420-33. [PMID: 15239391 DOI: 10.1532/ijh97.04032] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chronic myeloid leukemia (CML) is a stem cell disorder caused by a constitutively activated tyrosine kinase, the Bcr-Abl oncoprotein. An inhibitor of this tyrosine kinase, imatinib mesylate, is rapidly becoming the first-line therapy for CML. However, the development of resistance to this drug is a frequent setback, particularly in patients in advanced phases of the disease. Several mechanisms of resistance have been described, the most frequent of which are amplification and/or mutations of the BCR-ABL gene. To overcome resistance, several approaches have been studied in vitro and in vivo. They include dose escalation of imatinib, combination of imatinib with chemotherapeutic drugs, alternative Bcr-Abl inhibitors, inhibitors of kinases downstream of Bcr-Abl, farnesyl and geranylgeranyl transferase inhibitors, histone deacetylase, proteasome and cyclin-dependent kinase inhibitors, arsenic trioxide, hypomethylating agents, troxacitabine, targeting Bcr-Abl messenger RNA, and immunomodulatory strategies. It is important to understand that these approaches differ in efficiency, which is often dependent on the mechanisms of resistance. Further investigations into the molecular mechanisms of disease and how to specifically target the abnormal processes will guide the design of new treatment modalities in future clinical trials.
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MESH Headings
- Antineoplastic Agents/pharmacology
- Antineoplastic Combined Chemotherapy Protocols/therapeutic use
- Benzamides
- Dose-Response Relationship, Drug
- Drug Administration Schedule
- Drug Resistance, Neoplasm
- Genes, abl/genetics
- Genes, abl/physiology
- Humans
- Imatinib Mesylate
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/physiopathology
- Piperazines/pharmacology
- Pyrimidines/pharmacology
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Affiliation(s)
- Chikashi Yoshida
- Department of Haematology, Imperial College London, Hammersmith Hospital, London, United Kingdom
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41
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Abstract
Chronic myelogenous leukemia (CML) evolves from a chronic phase characterized by the Philadelphia chromosome as the sole genetic abnormality into blast crisis, which is often associated with additional chromosomal and molecular secondary changes. Although the pathogenic effects of most CML blast crisis secondary changes are still poorly understood, ample evidence suggests that the phenotype of CML blast crisis cells (enhanced proliferation and survival, differentiation arrest) depends on cooperation of BCR/ABL with genes dysregulated during disease progression. Most genetic abnormalities of CML blast crisis have a direct or indirect effect on p53 or Rb (or both) gene activity, which are primarily required for cell proliferation and survival, but not differentiation. Thus, the differentiation arrest of CML blast crisis cells is a secondary consequence of these abnormalities or is caused by dysregulation of differentiation-regulatory genes (ie, C/EBPalpha). Validation of the critical role of certain secondary changes (ie, loss of p53 or C/EBPalpha function) in murine models of CML blast crisis and in in vitro assays of BCR/ABL transformation of human hematopoietic progenitors might lead to the development of novel therapies based on targeting BCR/ABL and inhibiting or restoring the gene activity gained or lost during disease progression (ie, p53 or C/EBPalpha).
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Affiliation(s)
- Bruno Calabretta
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson Medical College, Philadelphia, PA 19107, USA.
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42
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Sattler M, Scheijen B, Weisberg E, Griffin JD. Mutated tyrosine kinases as therapeutic targets in myeloid leukemias. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 532:121-40. [PMID: 12908554 DOI: 10.1007/978-1-4615-0081-0_11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Tyrosine kinases are commonly mutated and activated in both acute and chronic myeloid leukemias. Here, we review the functions, signaling activities, mechanism of transformation, and therapeutic targeting of two prototypic tyrosine kinase oncogenes, BCR-ABL and FLT3, associated with chronic myeloid leukemia (CML) and acute myeloid leukemia (AML), respectively. BCR-ABL is generated by the Philadelphia chromosome translocation between chromosomes 9 and 22, creating a chimeric oncogene in which the BCR and c-ABL genes are fused. The product of this oncogene, BCR-ABL, has elevated ABL tyrosine kinase activity and transforms hematopoietic cells by exerting a wide variety of biological effects, including reduction in growth factor dependence, enhanced viability, and altered adhesion of chronic myelocytic leukemia (CML) cells. Elevated tyrosine kinase activity of BCR-ABL is critical for activating downstream signalling cascades and for all aspects of transformation, explaining the remarkable clinical efficacy of the tyrosine kinase inhibitor, imatinib mesylate (STI571). By comparison, FLT3 is mutated in about one third of all cases of AML, most often through a mechanism that involves an internal tandem duplication (ITD) of a small number of amino acid residues in the juxtamembrane domain of the receptor. As is the case for BCR-ABL, these mutations activate the kinase activity constitutively, activate multiple signaling pathways, and result in an augmentation of proliferation and viability. Transformation by FLT3-ITD can readily be observed in murine models, and FLT3 cooperates with other types of oncogenes to create a fully transformed acute leukemia. FLT3 tyrosine kinase inhibitors are currently being evaluated in clinical trials and may be very useful therapeutic agents in AML.
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Affiliation(s)
- Martin Sattler
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
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43
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Trajkovic V, Vuckovic O, Stosic-Grujicic S, Miljkovic D, Popadic D, Markovic M, Bumbasirevic V, Backovic A, Cvetkovic I, Harhaji L, Ramic Z, Mostarica Stojkovic M. Astrocyte-induced regulatory T cells mitigate CNS autoimmunity. Glia 2004; 47:168-79. [PMID: 15185395 DOI: 10.1002/glia.20046] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Although astrocytes presumably participate in maintaining the immune privilege of the central nervous system (CNS), the mechanisms behind their immunoregulatory properties are still largely undefined. In this study, we describe the development of regulatory T cells upon contact with astrocytes. Rat T cells pre-incubated with astrocytes completely lost the ability to proliferate in response to mitogenic stimuli. The cells were blocked in G0/G1 phase of the cell cycle, expressed less IL-2R, and produced significantly lower amounts of interferon-gamma (IFN-gamma), but not interleukin-2 (IL-2), IL-10, or tumor necrosis factor (TNF). These anergic cells completely prevented mitogen-induced growth of normal T lymphocytes, as well as CNS antigen-driven proliferation of autoreactive T cells. The suppressive activity resided in both CD4+ and CD8+ T-cell compartments. Heat-sensitive soluble T-cell factors, not including transforming growth factor-beta (TGF-beta) or IL-10, were solely responsible for the observed suppression, as well as for the transfer of suppressive activity to normal T cells. The administration of astrocyte-induced regulatory T cells markedly alleviated CNS inflammation and clinical symptoms of CNS autoimmunity in rats with experimental allergic encephalomyelitis. Finally, the cells with suppressive properties were readily generated from human lymphocytes after contact with astrocytes. Taken together, these data indicate that astrocyte-induced regulatory T cells might represent an important mechanism for self-limitation of excessive inflammation in the brain.
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Affiliation(s)
- Vladimir Trajkovic
- Institute of Microbiology and Immunology, School of Medicine, University of Belgrade, Belgrade, Serbia and Montenegro
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Keeshan K, Cotter TG, McKenna SL. Bcr-Abl upregulates cytosolic p21WAF-1/CIP-1 by a phosphoinositide-3-kinase (PI3K)-independent pathway. Br J Haematol 2003; 123:34-44. [PMID: 14510940 DOI: 10.1046/j.1365-2141.2003.04538.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Chronic myeloid leukaemia invariably progresses from a drug-sensitive to a drug-resistant, aggressive acute leukaemia. The mechanisms responsible for this are unknown, although loss of p53 has been reported in approximately 25% of cases. Elevated expression of Bcr-Abl is also associated with disease progression. We have shown that cells expressing high levels of Bcr-Abl also express elevated levels of p53 and the cell cycle inhibitor, p21WAF-1. Despite this, cells continue to cycle and are drug resistant. As p21WAF-1 inhibitory activity is associated with nuclear localization, we investigated its localization in Bcr-Abl-expressing cells, and found that it is predominantly cytoplasmic. We have also shown that it associates physically with the serine/threonine kinase AKT, but this association and the cytosolic location of p21WAF-1 are phosphinositide-3-kinase (PI3K) independent. Cytosolic p21WAF-1 has been reported to have a prosurvival role in other transformed cells. In Bcr-Abl-expressing cells, p21WAF-1 rapidly diminishes as the cells are sensitized to apoptosis, using the inhibitor STI571. It is possible therefore that p21WAF-1 could also have a positive, prosurvival role in these cells. This study suggests that, by retaining p21WAF-1 in a cytosolic location, Bcr-Abl can evade the cell cycle arrest normally induced by nuclear p21WAF-1 and therefore also enable the cells to negate an important feature of a tumour suppressor response.
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Affiliation(s)
- Karen Keeshan
- Department of Pathology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA, USA
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Wohlbold L, van der Kuip H, Miething C, Vornlocher HP, Knabbe C, Duyster J, Aulitzky WE. Inhibition of bcr-abl gene expression by small interfering RNA sensitizes for imatinib mesylate (STI571). Blood 2003; 102:2236-9. [PMID: 12750174 DOI: 10.1182/blood-2002-12-3899] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bcr-Abl proteins are effective inducers of the leukemic phenotype in chronic myeloid leukemia (CML) and distinct variants of acute lymphoblastic leukemia (ALL). Targeting bcr-abl by treatment with the selective tyrosine kinase inhibitor imatinib has proved to be highly efficient for controlling leukemic growth. However, it is unclear whether imatinib is sufficient to eradicate the disease because of primary or secondary resistance of leukemic cells. Therefore, targeting Bcr-Abl with an alternative approach is of great interest. We demonstrate that RNA interference (RNAi) with a breakpoint-specific short-interfering RNA (siRNA) is capable of decreasing Bcr-Abl protein expression and of antagonizing Bcr-Abl-induced biochemical activities. RNAi selectively inhibited Bcr-Abl-dependent cell growth. Furthermore, bcr-abl-homologous siRNA increased sensitivity to imatinib in Bcr-Abl-overexpressing cells and in a cell line expressing the imatinib-resistant Bcr-Abl kinase domain mutation His396Pro, thereby antagonizing 2 of the major mechanisms of resistance to imatinib.
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MESH Headings
- Antineoplastic Agents/pharmacology
- Benzamides
- Cell Division/drug effects
- Cell Survival/drug effects
- Drug Resistance, Neoplasm
- Fusion Proteins, bcr-abl/genetics
- Gene Expression Regulation, Leukemic/drug effects
- Humans
- Imatinib Mesylate
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Piperazines/pharmacology
- Pyrimidines/pharmacology
- RNA, Small Interfering/pharmacology
- Tumor Cells, Cultured
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Affiliation(s)
- Lara Wohlbold
- Robert-Bosch-Krankenhaus, Auerbachstrasse 110, 70376 Stuttgart, Germany
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Iorio A, Guercini F, Pini M. Low-molecular-weight heparin for the long-term treatment of symptomatic venous thromboembolism: meta-analysis of the randomized comparisons with oral anticoagulants. J Thromb Haemost 2003; 1:1906-13. [PMID: 12941030 DOI: 10.1046/j.1538-7836.2003.00364.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The management of venous thromboembolism (VTE) requires an initial treatment with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH), followed by oral anticoagulants (OA) for at least 3 months. OA treatment however, requires laboratory monitoring of anticoagulation, carries a definite risk of bleeding, and may be contraindicated in some patients. As an alternative to vitamin K antagonists, subcutaneous LMWH has been proposed and evaluated in randomized clinical trials, but they are all small studies that lack the power to establish if these two treatment modalities are equivalent in efficacy or safety. OBJECTIVES The objective of this review was to evaluate the efficacy (VTE recurrence) and safety (bleeds and deaths) of long-term treatment of VTE with LMWH compared with OA. A secondary endpoint was to evaluate the effect of LMWH on cancer mortality. METHODS Computerized searches of MedLine and EmBase were performed. In addition, randomized clinical trials were located through personal communication with colleagues, and through the manual scanning of meeting proceedings and reference lists of relevant studies. When necessary, the authors of the selected papers were called to obtain additional information. Two reviewers (AI and FG) reviewed and extracted data independently using a standard form. The primary analysis was performed for efficacy and safety endpoints on an intention-to-treat basis for the study period of randomized treatment. A meta-regression analysis was used to investigate the relationship between daily dose and clinical outcome. RESULTS Seven studies that fulfillled our predefined criteria were identified, for a total of 1379 patients. When all studies were combined, a statistically non-significant reduction in the risk of VTE (OR 0.66; 95% confidence interval [CI] 0.41, 1.07) and in the risk of major bleeding (OR 0.45; 95% CI 0.18, 1.11) in favor of LMWH treatment was found. No difference in total mortality (OR 1.19; 95% CI 0.78, 1.83) or in cancer-related mortality was observed between the LMWH and the OA treatment. CONCLUSIONS The results of this meta-analysis indicate that a 3-month course of LMWH is as effective and safe as a corresponding period of OA treatment, and may thus be considered as a valuable alternative option for patients in whom OA treatment appears contraindicated or problematic.
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Affiliation(s)
- A Iorio
- Sezione de Medicina Interna e Cardiovasculare, Università di Perugia, Perugia, Italy.
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Clarkson B, Strife A, Wisniewski D, Lambek CL, Liu C. Chronic myelogenous leukemia as a paradigm of early cancer and possible curative strategies. Leukemia 2003; 17:1211-62. [PMID: 12835715 DOI: 10.1038/sj.leu.2402912] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The chronological history of the important discoveries leading to our present understanding of the essential clinical, biological, biochemical, and molecular features of chronic myelogenous leukemia (CML) are first reviewed, focusing in particular on abnormalities that are responsible for the massive myeloid expansion. CML is an excellent target for the development of selective treatment because of its highly consistent genetic abnormality and qualitatively different fusion gene product, p210(bcr-abl). It is likely that the multiple signaling pathways dysregulated by p210(bcr-abl) are sufficient to explain all the initial manifestations of the chronic phase of the disease, although understanding of the circuitry is still very incomplete. Evidence is presented that the signaling pathways that are constitutively activated in CML stem cells and primitive progenitors cooperate with cytokines to increase the proportion of stem cells that are activated and thereby increase recruitment into the committed progenitor cell pool, and that this increased activation is probably the primary cause of the massive myeloid expansion in CML. The cooperative interactions between Bcr-Abl and cytokine-activated pathways interfere with the synergistic interactions between multiple cytokines that are normally required for the activation of stem cells, while at the same time causing numerous subtle biochemical and functional abnormalities in the later progenitors and precursor cells. The committed CML progenitors have discordant maturation and reduced proliferative capacity compared to normal committed progenitors, and like them, are destined to die after a limited number of divisions. Thus, the primary goal of any curative strategy must be to eliminate all Philadelphia positive (Ph+) primitive cells that are capable of symmetric division and thereby able to expand the Ph+ stem cell pool and recreate the disease. Several highly potent and moderately selective inhibitors of Bcr-Abl kinase have recently been discovered that are capable of killing the majority of actively proliferating early CML progenitors with minimal effects on normal progenitors. However, like their normal counterparts, most of the CML primitive stem cells are quiescent at any given time and are relatively invulnerable to the Bcr-Abl kinase inhibitors as well as other drugs. We propose that survival of dormant Ph+ stem cells may be the most important reason for the inability to cure the disease during initial treatment, while resistance to the inhibitors and other drugs becomes increasingly important later. An outline of a possible curative strategy is presented that attempts to take advantage of the subtle differences in the proliferative behavior of normal and Ph+ stem cells and the newly discovered selective inhibitors of Bcr-Abl. Leukemia (2003) 17, 1211-1262. doi:10.1038/sj.leu.2402912
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MESH Headings
- Antineoplastic Agents/therapeutic use
- Fusion Proteins, bcr-abl/antagonists & inhibitors
- Fusion Proteins, bcr-abl/genetics
- Hematopoietic Stem Cells/pathology
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/etiology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/therapy
- Signal Transduction
- Treatment Outcome
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Affiliation(s)
- B Clarkson
- Molecular Pharmacology and Chemistry Program, Sloan-Kettering Institute for Cancer Research, New York, NY 10021, USA
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Le XF, Claret FX, Lammayot A, Tian L, Deshpande D, LaPushin R, Tari AM, Bast RC. The role of cyclin-dependent kinase inhibitor p27Kip1 in anti-HER2 antibody-induced G1 cell cycle arrest and tumor growth inhibition. J Biol Chem 2003; 278:23441-50. [PMID: 12700233 DOI: 10.1074/jbc.m300848200] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyclin-dependent kinase (CDK) inhibitor p27Kip1 binds to the cyclin E.CDK2 complex and plays a major role in controlling cell cycle and cell growth. Our group and others have reported that anti-HER2 monoclonal antibodies exert inhibitory effects on HER2-overexpressing breast cancers through G1 cell cycle arrest associated with induction of p27Kip1 and reduction of CDK2. The role of p27Kip1 in anti-HER2 antibody-induced cell cycle arrest and growth inhibition is, however, still uncertain. Here we have provided several lines of evidence supporting a critical role for p27Kip1 in the anti-HER2 antibody-induced G1 cell cycle arrest and tumor growth inhibition. Induction of p27Kip1 and G1 growth arrest by anti-HER2 antibody, murine 4D5, or humanized trastuzumab (Herceptin) are concentration-dependent, time-dependent, irreversible, and long-lasting. The magnitude of G1 cell cycle arrest induced by trastuzumab or 4D5 is well correlated with the level of p27Kip1 protein induced. Up-regulation of p27Kip1 and G1 growth arrest could no longer be removed with as little as 14 h of treatment with trastuzumab. Anti-HER2 antibody-induced p27Kip1 protein, G1 arrest, and growth inhibition persist at least 5 days after a single treatment. The magnitude of growth inhibition of breast cancer cells induced by anti-HER2 antibody closely parallels the level of p27Kip1 induced. Induced expression of exogenous p27Kip1 results in a p27Kip1 level-dependent G1 cell cycle arrest and growth inhibition similar to that obtained with anti-HER2 antibodies. Reducing p27Kip1 expression using p27Kip1 small interfering RNA blocks anti-HER2 antibody-induced p27Kip1 up-regulation and G1 arrest. Treatment with anti-HER2 antibody significantly increases the half-life of p27Kip1 protein. Inhibition of ubiquitin-proteasome pathway, but not inhibition of calpain and caspase activities, up-regulates p27Kip1 protein to a degree comparable with that obtained with anti-HER2 antibodies. We have further demonstrated that anti-HER2 antibody significantly decreases threonine phosphorylation of p27Kip1 protein at position 187 (Thr-187) and increases serine phosphorylation of p27Kip1 protein at position 10 (Ser-10). Expression of S10A and T187A mutant p27Kip1 protein increases the fraction of cells in G1 and reduces a further antibody-induced G1 arrest. Consequently, p27Kip1 plays an important role in the anti-HER2 antibody-induced G1 cell cycle arrest and tumor growth inhibition through post-translational regulation. Regulation of the phosphorylation of p27Kip1 protein is one of the post-translational mechanisms by which anti-HER2 antibody upregulates the protein.
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Affiliation(s)
- Xiao-Feng Le
- Department of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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Drexler HCA, Pebler S. Inducible p27(Kip1) expression inhibits proliferation of K562 cells and protects against apoptosis induction by proteasome inhibitors. Cell Death Differ 2003; 10:290-301. [PMID: 12700629 DOI: 10.1038/sj.cdd.4401159] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Overexpression of the cyclin-dependent kinase inhibitor p27(Kip1) has been demonstrated to induce cell cycle arrest and apoptosis in various cancer cell lines, but has also been associated with the opposite effect of enhanced survival of tumor cells and increased resistance towards chemotherapeutic treatment. To address the question of how p27(Kip1) expression is related to apoptosis induction, we studied doxycycline-regulated p27(Kip1) expression in K562 erythroleukemia cells. p27(Kip1) expression effectively retards proliferation, but it is not sufficient to induce apoptosis in K562 cells. p27(Kip1)-expressing K562 cells, however, become resistant to apoptosis induction by the proteasome inhibitors PSI, MG132 and epoxomicin, in contrast to wild-type K562 cells that are efficiently killed. Cell cycle arrest in the S phase by aphidicolin, which is not associated with an accumulation of p27(Kip1) protein, did not protect K562 cells against the cytotoxic effect of the proteasome inhibitor PSI. The expression levels of p27(Kip1) thus constitute an important parameter, which decides on the overall sensitivity of cells against the cytotoxic effect of proteasome inhibitors.
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Affiliation(s)
- H C A Drexler
- Max Planck Institute for Physiological and Clinical Research, Department of Molecular Cell Biology, Bad Nauheim, Germany.
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Komatsu N, Watanabe T, Uchida M, Mori M, Kirito K, Kikuchi S, Liu Q, Tauchi T, Miyazawa K, Endo H, Nagai T, Ozawa K. A member of Forkhead transcription factor FKHRL1 is a downstream effector of STI571-induced cell cycle arrest in BCR-ABL-expressing cells. J Biol Chem 2003; 278:6411-9. [PMID: 12456669 DOI: 10.1074/jbc.m211562200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A member of the Forkhead transcription factor family, FKHRL1, lies downstream of the phosphatidylinositol 3-kinase-Akt activation pathway in cytokine signaling. Because the phosphatidylinositol 3-kinase-Akt activation pathway is required for BCR-ABL-mediated transformation and survival signaling in chronic myelogenous leukemia (CML), in this study we examined the involvement of FKHRL1 in the BCR-ABL-mediated signaling pathway. FKHRL1 was constitutively phosphorylated in BCR-ABL-expressing cell lines KCL22 and KU812, and its phosphorylation was inhibited by treatment with STI571, a specific inhibitor of BCR-ABL tyrosine kinase. Concomitantly, STI571 induced cell cycle arrest at the G(0)/G(1) phase, accompanied by up-regulation of a cyclin-dependent kinase inhibitor p27/Kip1 in KCL22 cells. In addition, FKHRL1 was constitutively phosphorylated in the TF-1/bcr-abl cell line ectopically expressing BCR-ABL but not in the parent TF-1 cell line. Considering several lines of evidence that phosphorylated FKHRL1 has lost transcriptional activity and that p27/Kip1 expression is positively regulated by dephosphorylated "active" FKHRL1, BCR-ABL may down-regulate p27/Kip1 expression via the loss of FKHRL1 function as a transcription factor. To demonstrate this hypothesis, we generated a tamoxifen-inducible "active FKHRL1" FKHRL1-TM (a triple mutant of FKHRL1, in which all three Akt phosphorylation sites have been mutated), estrogen receptor system in the KCL22 cell line. The addition of tamoxifen inhibited the cell growth indicating that overexpression of FKHRL1 in the nucleus antagonized deregulated proliferation of CML cells. Collectively, FKHRL1 regulates the expression of p27/Kip1 as a downstream molecule of BCR-ABL signaling in CML cells. BCR-ABL-induced loss of FKHRL1 function may be involved in oncogenic transformation of CML partially via the down-regulation of p27/Kip1 proteins.
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Affiliation(s)
- Norio Komatsu
- Division of Hematology, Department of Medicine, Jichi Medical School, Tochigi 329-0498, Japan.
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