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

The relationship between the Src kinase Lyn and Bcl-2 expression was examined in chronic myelogenous leukemia cells (K562 and LAMA84) displaying a Bcr/Abl-independent form of imatinib mesylate resistance. K562-R and LAMA-R cells that were markedly resistant to induction of mitochondrial dysfunction (e.g. loss of mitochondrial membrane potential, Bax translocation, cytochrome c, and apoptosis-inducing factor release) and apoptosis by imatinib mesylate exhibited a pronounced reduction in expression of Bcr/Abl, Bcl-x(L), and STAT5 but a striking increase in levels of activated Lyn. Whereas basal expression of Bcl-2 protein was very low in parental cells, imatinib-resistant cells displayed a marked increase in Bcl-2 mRNA and/or protein levels. Treatment of LAMA-R cells with the Src kinase inhibitor PP2 significantly reduced Lyn activation as well as Bcl-2 mRNA and protein levels. Transient or stable transfection of LAMA84 or K562 cells with a constitutively active Lyn (Y508F), but not with a kinase-dead mutant (K275D), significantly increased Bcl-2 protein expression and protected cells from lethality of imatinib mesylate. Ectopic expression of Bcl-2 protected K562 and LAMA84 cells from imatinib mesylate- and PP2-mediated lethality. Conversely, interference with Bcl-2 function by co-administration of the small molecule Bcl-2 inhibitor HA14-1 or down-regulation of Bcl-2 expression by small interfering RNA or antisense strategies significantly increased mitochondrial dysfunction and apoptosis induced by imatinib mesylate and the topoisomerase inhibitor VP-16 in LAMA-R cells. In marked contrast, these interventions had little effect in parental LAMA84 cells that display low basal levels of Bcl-2. Together, these findings indicate that activation of Lyn in leukemia cells displaying a Bcr/Abl-independent form of imatinib mesylate resistance plays a functional role in Bcl-2 up-regulation and provide a theoretical basis for the development of therapeutic strategies targeting Bcl-2 in such a setting.
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PMID:A Bcr/Abl-independent, Lyn-dependent form of imatinib mesylate (STI-571) resistance is associated with altered expression of Bcl-2. 1517 50

To study the effect of curcumin on signaling pathway of signal transducers and activators of transcription (STAT5) in primary newly-diagnosed chronic myelocytic leukemia (CML) cells, and to explore the clinical significance of curcumin in the treatment of primary CML cells, the cells were randomly divided into 3 groups: normal control group, CML cells group, and curcumin group; the cellular proliferation was assayed by MTT test; the expression of cellular STAT5 mRNA in CML cells was detected by RT-PCR; the activation of STAT5 in CML cell was detected by electrophoretic mobility shift assay (EMSA). The results showed that the cellular proliferation of curcumin group (OD value 0.640 +/- 0.073) was decreased, as compared with that of the CML cells group (OD value 0.856 +/- 0.083, P <0.01). The expression levels of STAT5 mRNA in CML cells group (integral ratio of OD 1.782 +/- 0.156) were significantly greater than that in the normal control group (integral ratio of OD 0.289 +/- 0.025, P <0.01). The expression of STAT5 mRNA in curcumin group (integral ratio of OD 1.398 +/- 0.126) was significantly decreased as compared with that in the CML cells group (P <0.01). The activation of STAT5 was significantly increased in CML cells group (gray value 5323.375 +/- 515.640) as compared with that in the normal control group (gray value 2943.000 +/- 273.377, P <0.01). The activation of STAT5 of curcumin group (gray value 4331.750 +/- 398.035) was significantly decreased as compared with that of CML cells group (P <0.01). It is concluded that the cellular proliferation and the expression of STAT5 mRNA are increased in the primary CML cells. The activation of STAT5 in primary CML cells is markedly enhanced. STAT5 signaling pathway may be involved in the proliferation of primary CML cells. Curcumin can inhibit the cellular proliferation and the expression of STAT5 mRNA, and down-regulate the activation of STAT5 in primary CML cells. Curcumin may be used in treatment of leukemia.
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PMID:[Effect of curcumin on STAT5 signaling pathway in primary CML cells]. 1549 13

This study was aimed to observe whether expressions of JAK2, STAT1, STAT5 proteins in indomethacin-treated CML cells involved in the proliferation inhibition of CML cells, and elucidate the pharmacological mechanism of indomethacin anti-leukemia. MTT assay and trypan blue dye exclusion test were used to detect the inhibitory effect of indomethacin on CML cells proliferation. JAK2, STAT1, STAT5 proteins were analyzed by Western blot; the subcellular distribution of STAT1, STAT5 were detected with indirect immunofluorescence technique. The results showed that indomethacin at >or= 400 micromol/L significantly inhibited the proliferation of CML cells and down-regulated the expression of STAT1, STAT5 protein, no JAK2 change was observed. STAT1 and STAT5 were located in cytoplasm. It is concluded that indomethacin inhibits the proliferation of CML cells and the mechanism may be related to down-regulated expression of STAT, or blockage of cells growth signals.
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PMID:[Proliferation-inhibiting effect of indomethacin on chronic myeliod leukemia cells is related to the supression of STAT signal transduction pathway]. 1563 56

Polycythemia vera (PV) is a clonal disorder of unknown etiology involving a multipotent hematopoietic progenitor cell that is characterized by the accumulation of phenotypically normal red blood cells, white blood cells, and platelets in the absence of a definable cause; extramedullary hematopoiesis, marrow fibrosis, and, in a few patients, transformation to acute leukemia can also occur. First described in 1892, the cause of the disease remains unknown and no potentially curative therapy other than bone marrow transplantation is currently available. It is commonly held that PV is a rare disorder, when in fact with a minimum incidence of 2.6 per 100,000 it is more common than chronic myelogenous leukemia (CML) and is particularly prevalent in persons of Ashkenazi Jewish ancestry. However, the incidence of PV is not as high as that of erythrocytosis from other causes collectively, which poses a problem in differential diagnosis when PV presents as isolated erythrocytosis. Characteristic features of PV are erythropoietin (Epo)-independent in vitro erythroid colony formation, as well as hypersensitivity to many other hematopoietic growth factors. Recently, a remarkable association between PV and a somatic point mutation of the JAK2 tyrosine kinase (JAK2 V617F) was described. Functional assays have revealed that JAK2 V617F is capable of inducing constitutive STAT5-mediated signaling in vitro, as well as erythrocytosis in vivo in mice. These data suggest that the JAK2 V617F mutation participates in the pathogenesis of PV. In current clinical practice, two different clinical approaches have been used to diagnose PV. One approach requires establishing the presence of absolute erythrocytosis by directly determining the red cell mass (RCM). A second approach utilizes a RCM-independent diagnostic algorithm based on the serum Epo level and bone marrow histology. Screening for JAK2 V617F can now be added to both diagnostic algorithms. However, it is very clear that some patients with classical PV lack the JAK2 V617F mutation, while some patients with other chronic myeloproliferative disorders such as idiopathic myelofibrosis (IMF) and essential thrombocytosis (ET) also express the JAK2 V617F mutation. Therefore, by necessity, any discussion of PV must take into consideration these companion myeloproliferative disorders, and since erythrocytosis is the single clinical feature that sets PV apart from IMF and ET, it is clear that the presence of the JAK2 V617F mutation cannot by itself establish a diagnosis of PV. Phlebotomy remains the mainstay of therapy for PV. In addition, both aspirin and cytoreductive therapy have been employed to control thrombocytosis and in the case of the latter, leukocytosis and extramedullary hematopoiesis as well. Despite recent progress in the field, several important issues remain controversial. In this review, we will present the areas of agreement, but also point out where the authors' personal viewpoints differ.
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PMID:Polycythemia vera: scientific advances and current practice. 1621 34

Although targeting the BCR-ABL tyrosine kinase activity by imatinib mesylate has rapidly become first-line therapy in chronic myeloid leukemia (CML), drug resistance suggests that combination therapy directed to a complementing target may significantly improve treatment results. To identify such potential targets, we used lentivirus-mediated RNA interference (RNAi) as a tool for functional genomics in cell lines as well as primary normal and CML CD34+ cells. In a conditional cell culture model, we demonstrate that RNAi-mediated reduction of SHP2, STAT5, and Gab2 protein expression inhibits BCR-ABL-dependent but not cytokine-dependent proliferation in a dose-dependent manner. Similarly, colony formation of purified primary CML but not of normal CD34+ colony-forming cells is specifically reduced by inhibition of SHP2, STAT5, and Gab2 expression, respectively. In addition, coexpression of both anti-BCR-ABL and anti-SHP2 shRNAs from a single lentiviral vector induces stronger inhibition of colony formation as compared to either shRNA alone. The data indicate that BCR-ABL expression may affect the function of normal signaling molecules. Targeting these molecules may harbor significant therapeutic potential for the treatment of patients with CML.
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PMID:Enhanced sensitivity to inhibition of SHP2, STAT5, and Gab2 expression in chronic myeloid leukemia (CML). 1627 4

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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PMID:Combined effects of novel tyrosine kinase inhibitor AMN107 and histone deacetylase inhibitor LBH589 against Bcr-Abl-expressing human leukemia cells. 1653 4

IL-2 plays a critical role in the maintenance of CD4+CD25+ FOXP3(+) regulatory T cells (Tregs) in vivo. We examined the effects of IL-2 signaling in human Tregs. In vitro, IL-2 selectively up-regulated the expression of FOXP3 in purified CD4+CD25+ T cells but not in CD4+CD25- cells. This regulation involved the binding of STAT3 and STAT5 proteins to a highly conserved STAT-binding site located in the first intron of the FOXP3 gene. We also examined the effects of low-dose IL-2 treatment in 12 patients with metastatic cancer and 9 patients with chronic myelogenous leukemia after allogeneic hematopoietic stem cell transplantation. Overall, IL-2 treatment resulted in a 1.9 median fold increase in the frequency of CD4+CD25+ cells in peripheral blood as well as a 9.7 median fold increase in FOXP3 expression in CD3+ T cells. CD56+CD3- natural killer (NK) cells also expanded during IL-2 therapy but did not express FOXP3. In vitro treatment of NK cells with 5-aza-2'-deoxycytidine restored the IL-2 signaling pathway leading to FOXP3 expression, suggesting that this gene was constitutively repressed by DNA methylation in these cells. Our findings support the clinical evaluation of low-dose IL-2 to selectively modulate CD4+CD25+ Tregs and increase expression of FOXP3 in vivo.
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PMID:IL-2 regulates FOXP3 expression in human CD4+CD25+ regulatory T cells through a STAT-dependent mechanism and induces the expansion of these cells in vivo. 1664 71

Imatinib metylase is the first choice treatment for BCR/ABL positive chronic myelogenous leukemia (CML). However, as some CML patients develop resistance to imatinib therapy, there is a significant interest in development of alternative treatment strategies, such as identifying targets other than BCR/ABL that may participate in CML. Previously, we demonstrated strong PCNA up-regulation in CML patients. To further study its role in CML pathogenesis, we performed silencing of PCNA expression followed by array experiments. PCNA inhibition led to down-regulation of CDK1, CDK4, PLK1, ERK3, JNK1, STAT5, and several inhibitors of apoptosis (DAXX, Mdm2, survivin). The following genes were up-regulated: CDK inhibitors p21 and p19-INK4D, pro-apoptotic FAST kinase, fibronectin, etc. However, as PCNA affects cell growth in naturally proliferating cells as well as in cancerous cells, it seems to act a secondary role relating to proliferation activity of leukemic cells.
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PMID:Expression analysis of PCNA gene in chronic myelogenous leukemia--combined application of siRNA silencing and expression arrays. 1707 Sep 5

Overcoming imatinib mesylate (IM) resistance and disease persistence in patients with chronic myeloid leukemia (CML) is of considerable importance to the issue of potential cure. Here we asked whether autocrine signaling contributes to survival of BCR/ABL+ cells in the presence of IM and nilotinib (NI; AMN107), a novel, more selective Abl inhibitor. Conditioned media (CM) of IM-resistant LAMA84 cell clones (R-CM) was found to substantially protect IM-naive LAMA cells and primary CML progenitors from IM- or NI-induced cell death. This was due to an increased secretion of the granulocyte-macrophage colony-stimulating factor (GM-CSF), which was identified as the causative factor mediating IM resistance in R-CM. GM-CSF elicited IM and NI drug resistance via a BCR/ABL-independent activation of the janus kinases 2 (JAK-2)/signal transducer and activator of transcription 5 (STAT-5) signaling pathway in GM-CSF receptor alpha receptor (CD116)-expressing cells, including primary CD34+/CD116+ GM progenitors (GMPs). Elevated mRNA and protein levels of GM-CSF were detected in IM-resistant patient samples, suggesting a contribution of GM-CSF secretion for IM and NI resistance in vivo. Importantly, inhibition of JAK-2 with AG490 abrogated GM-CSF-mediated STAT-5 phosphorylation and NI resistance in vitro. Together, adaptive autocrine secretion of GM-CSF mediates BCR/ABL-independent IM and NI resistance via activation of the antiapoptotic JAK-2/STAT-5 pathway. Inhibition of JAK-2 overcomes GM-CSF-induced IM and NI progenitor cell resistance, providing a rationale for the application of JAK-2 inhibitors to eradicate residual disease in CML.
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PMID:Adaptive secretion of granulocyte-macrophage colony-stimulating factor (GM-CSF) mediates imatinib and nilotinib resistance in BCR/ABL+ progenitors via JAK-2/STAT-5 pathway activation. 1709 Jun 51

Bcr-Abl activity in chronic myelogenous leukemia (CML) results in dysregulated cell proliferation and resistance against multiple cytotoxic agents due to the constitutive activation of proliferative signaling pathways. Currently, the most effective treatment of CML is the inhibition of Bcr-Abl activity by imatinib mesylate (Gleevec). Imatinib efficacy is limited by development of resistance through either expression of Bcr-Abl variants that bind imatinib less avidly, increased expression of Bcr-Abl, or expression of multidrug transport proteins. N-Benzyladriamycin-14-valerate (AD 198) is a novel antitumor PKC activating agent that triggers rapid apoptosis through PKC-delta activation and mitochondrial depolarization in a manner that is unaffected by Bcl-2 expression. We demonstrate that Bcr-Abl expression does not confer resistance to AD 198. Further, AD 198 rapidly induces Erk1/2 and STAT5 phosphorylation prior to cytochrome c release from mitochondria, indicating that proliferative pathways are active even as drug-treated cells undergo apoptosis. At sub-cytotoxic doses, AD 198 and its cellular metabolite, N-benzyladriamycin (AD 288) sensitize CML cells to imatinib through a supra-additive reduction in the level of Bcr-Abl protein expression. These results suggest that AD 198 is an effective treatment for CML both in combination with imatinib and alone against imatinib-resistant CML cells.
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PMID:N-Benzyladriamycin-14-valerate (AD 198) cytotoxicty circumvents Bcr-Abl anti-apoptotic signaling in human leukemia cells and also potentiates imatinib cytotoxicity. 1718 56


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