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CML Cells (cml + cell)
Selected AbstractsExpression of angiogenic factors in chronic myeloid leukaemia: role of the bcr/abl oncogene, biochemical mechanisms, and potential clinical implicationsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2004C. Sillaber Abstract Chronic myeloid leukaemia (CML) is a stem cell disease characterized by an increased production and accumulation of clonal BCR/ABL,positive cells in haematopoietic tissues. The chronic phase of CML is inevitably followed by an accelerated phase of the disease, with consecutive blast crisis. However, depending on genetic stability, epigenetic events, and several other factors, the clinical course and survival appear to vary among patients. Recent data suggest that angiogenic cytokines such as vascular endothelial growth factor (VEGF), are up-regulated in CML, and play a role in the pathogenesis of the disease. These factors appear to be produced and released in leukaemic cells in patients with CML. In line with this notion, increased serum-levels of angiogenic growth factors are measurable in CML patients. In this study we provide an overview of angiogenic growth factors expressed in CML cells, discuss the possible pathogenetic role of these cytokines, the biochemical basis of their production in leukaemic cells, and their potential clinical implications. [source] NF-,B inhibition triggers death of imatinib-sensitive and imatinib-resistant chronic myeloid leukemia cells including T315I Bcr-Abl mutantsINTERNATIONAL JOURNAL OF CANCER, Issue 2 2009Nadia Lounnas Abstract The Bcr-Abl inhibitor imatinib is the current first-line therapy for all newly diagnosed chronic myeloid leukemia (CML). Nevertheless, resistance to imatinib emerges as CML progresses to an acute deadly phase implying that physiopathologically relevant cellular targets should be validated to develop alternative therapeutic strategies. The NF-,B transcription factor that exerts pro-survival actions is found abnormally active in numerous hematologic malignancies. In the present study, using Bcr-Abl-transfected BaF murine cells, LAMA84 human CML cell line and primary CML, we show that NF-,B is active downstream of Bcr-Abl. Pharmacological blockade of NF-,B by the IKK2 inhibitor AS602868 prevented survival of BaF cells expressing either wild-type, M351T or T315I imatinib-resistant mutant forms of Bcr-Abl both in vitro and in vivo using a mouse xenograft model. AS602868 also affected the survival of LAMA84 cells and of an imatinib-resistant variant. Importantly, the IKK2 inhibitor strongly decreased in vitro survival and ability to form hematopoietic colonies of primary imatinib resistant CML cells including T315I cells. Our data strongly support the targeting of NF-,B as a promising new therapeutic opportunity for the treatment of imatinib resistant CML patients in particular in the case of T315I patients. The T315I mutation escapes all currently used Bcr-Abl inhibitors and is likely to become a major clinical problem as it is associated with a poor clinical outcome. © 2009 UICC [source] Pml and TAp73 interacting at nuclear body mediate imatinib-induced p53-independent apoptosis of chronic myeloid leukemia cellsINTERNATIONAL JOURNAL OF CANCER, Issue 1 2009Jin-Hwang Liu Abstract Bcr-abl signals for leukemogenesis of chronic myeloid leukemia (CML) and activates ras. Since the function of promyelocytic leukemia protein (pml) is provoked by ras to promote apoptosis and senescence in untransformed cells, the function is probably masked in CML. Imatinib specifically inhibits bcr-abl and induces apoptosis of CML cells. As reported previously, p53wild CML was more resistant to imatinib than that lacking p53. Here, we searched for an imatinib-induced p53 independent proapoptotic mechanism. We found imatinib up-regulated phosphorylation of p38 mitogen-activated protein kinase (MAPK), checkpoint kinase 2 (chk2) and transactivation-competent (TA) p73; expression of pml and bax; formation of PML-nuclear body (NB); and co-localization of TAp73/PML-NB in p53-nonfunctioning K562 and p53mutant Meg-01 CML cells, but not in BCR-ABL - HL60 cells. In K562 cells, with short interfering RNAs (siRNAs), knockdown of pml led to dephosphorylation of TAp73. Knockdown of either pml or TAp73 abolished the imatinib-induced apoptosis. Inhibition of p38 MAPK with SB203580 led to dephosphorylation of TAp73, abolishment of TAp73/PML-NB co-localization, and the subsequent apoptosis. Conversely, interferon ,-2a (IFN,), which increased phosphrylated TAp73 and TAp73/PML-NB co-localization, increased additively apoptosis with imatinib. The imatinib-induced TAp73/PML-NB co-localization was accompanied by co-immpunoprecipitation of TAp73 with pml. The imatinib-induced co-localization was also found in primary CML cells from 3 of 6 patients, including 2 with p53mutant and one with p53wild. A novel p53-independent proapoptotic mechanism using p38 MAPK /pml/TAp73 axis with a step processing at PML-NB and probably with chk2 and bax being involved is hereby evident in some imatinib-treated CML cells. © 2009 UICC [source] Quantification of change in phosphorylation of BCR-ABL kinase and its substrates in response to Imatinib treatment in human chronic myelogenous leukemia cellsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 16 2006Xiquan Liang Dr. Abstract Phosphorylation by the constitutively activated BCR-ABL tyrosine kinase is associated with the pathogenesis of the human chronic myelogenous leukemia,(CML). It is difficult to characterize kinase response to stimuli or drug treatment because regulatory phosphorylation events are largely transient changes affecting low abundance proteins. Stable isotope labeling with amino acids in cell culture,(SILAC) has emerged as a pivotal technology for quantitative proteomics. By metabolically labeling proteins with light or heavy tyrosine, we are able to quantify the change in phosphorylation of BCR-ABL kinase and its substrates in response to drug treatment in human CML cells. In this study, we observed that BCR-ABL kinase is phosphorylated at tyrosines,393 and 644, and that SH2-domain containing inositol phosphatase (SHIP)-2 and downstream of kinase (Dok)-2 are phosphorylated at tyrosine,1135 and 299, respectively. Based on the relative intensity of isotopic peptide pairs, we demonstrate that the level of phosphorylation of BCR-ABL kinase as well as SHIP-2 and Dok-2 is reduced approximately 90% upon treatment with Imatinib, a specific inhibitor of BCR-ABL kinase. Furthermore, proteins, such as SHIP-1, SH2-containing protein (SHC) and Casitas B-lineage lymphoma proto-oncogene (CBL), are also regulated by Imatinib. These results demonstrate the simplicity and utility of SILAC as a method to quantify dynamic changes in phosphorylation at specific sites in response to stimuli or drug treatment in cell culture. [source] HLA-DRB1*16-restricted recognition of myeloid cells, including CD34+ CML progenitor cellsBRITISH JOURNAL OF HAEMATOLOGY, Issue 5 2003Saskia B. Ebeling Summary. The therapeutic effect of a human leucocyte antigen (HLA)-identical allogeneic stem cell transplantation (allo-SCT) for the treatment of haematological malignancies is mediated partly by the allogeneic T cells that are administered together with the stem cell graft. Chronic myeloid leukaemia (CML) is particularly sensitive to this graft-versus-leukaemia (GVL) effect. Several studies have shown that in allogeneic responses both CD4 and CD8 cells are capable of strong antigen-specific growth inhibition of leukaemic progenitor cells, but that CD4 cells mainly exert the GVL effect against CML. Efficient activation of allogeneic CD4 cells, as well as CD8 cells, may explain the sensitivity of CML cells to elimination by allogeneic T cells. Identification of the antigens recognized by CD4 cells is crucial in understanding the mechanism through which CML cells are so successful in activating allogeneic T cells. In the present report, we describe the characterization of an allogeneic CD4 T-cell clone, DDII.4.4. This clone was found to react against an antigen that is specifically expressed in myeloid cells, including CD34+ CML cells. The antigen recognition is restricted by HLA-DRB1*16. To our knowledge, this is only the second report on an allogeneic CD4 T-cell clone that reacts with early CD34+ myeloid progenitor cells. [source] Contribution of BCR,ABL-independent activation of ERK1/2 to acquired imatinib resistance in K562 chronic myeloid leukemia cellsCANCER SCIENCE, Issue 1 2010Takeru Nambu BCR,ABL tyrosine kinase, generated from the reciprocal chromosomal translocation t(9;22), causes chronic myeloid leukemia (CML). BCR,ABL is inhibited by imatinib; however, several mechanisms of imatinib resistance have been proposed that account for loss of imatinib efficacy in patients with CML. Previously, we showed that overexpression of the efflux drug transporter P-glycoprotein partially contributed to imatinib resistance in imatinib-resistant K562 CML cells having no BCR,ABL mutations. To explain an additional mechanism of drug resistance, we established a subclone (K562/R) of the cells and examined the BCR,ABL signaling pathway in these and wild-type K562 (K562/W) cells. We found the K562/R cells were 15 times more resistant to imatinib than their wild-type counterparts. In both cell lines, BCR,ABL and its downstream signaling molecules, such as ERK1/2, ERK5, STAT5, and AKT, were phosphorylated in the absence of imatinib. In both cell lines, imatinib effectively reduced the phosphorylation of all the above, except ERK1/2, whose phosphorylation was, interestingly, only inhibited in the wild-type cells. We then observed that phospho-ERK1/2 levels decreased in the presence of siRNA targeting BCR,ABL, again, only in the K562/W cells. However, using an ERK1/2 inhibitor, U0126, we found that we could reduce phospho-ERK1/2 levels in K562/R cells and restore their sensitivity to imatinib. Taken together, we conclude that the BCR,ABL-independent activation of ERK1/2 contributes to imatinib resistance in K562/R cells, and that ERK1/2 could be a target for the treatment of CML patients whose imatinib resistance is due to this mechanism. (Cancer Sci 2009) [source] Active FKHRL1 overcomes imatinib resistance in chronic myelogenous leukemia-derived cell lines via the production of tumor necrosis factor-related apoptosis-inducing ligandCANCER SCIENCE, Issue 12 2007Satoru Kikuchi FKHRL1 (also called FOXO3a) is a member of the Forkhead Box, class O (FOXO) subfamily of forkhead transcription factors and functions downstream of Bcr,Abl tyrosine kinase as a phosphorylated inactive form in chronic myelogenous leukemia (CML). The Bcr,Abl tyrosine kinase inhibitor imatinib induces cell cycle arrest and subsequent apoptosis via the conversion of FKHRL1 from the phosphorylated inactive form to the dephosphorylated active form in CML-derived cell lines. In the present study, we examined whether active FKHRL1 can overcome resistance to imatinib. To this end, we generated a 4-hydroxytamoxifen-inducible active FKHRL1 (FKHRL1-TM; a triple mutant of FKHRL1 in which all three Akt phosphorylation sites have been mutated),estrogen receptor fusion protein expression system in CML-derived imatinib-resistant cell lines. 4-Hydroxytamoxifen inhibited cell growth and cell cycle progression, and subsequently induced apoptosis, accompanied by upregulation of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Thus, active FKHRL1 antagonized deregulated proliferation and induced apoptosis in these cell lines. In addition, imatinib-resistant cells underwent apoptosis after transfection with full-length TRAIL cDNA. Collectively, our results suggest that active FKHRL1 can overcome imatinib resistance in CML cells, in part via TRAIL production. (Cancer Sci 2007; 98: 1949,1958) [source] | ||||||||||