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

We have tested whether peripheral blood mononuclear cells (PBMNCs) from interferon (IFN)-treated patients may lose residual BCR-ABL sequence-positive progenitor cells when long-term cultured for 35 days on allogeneic stromal cells. IFN-treated patients have low white blood cell counts and a fair number of BCR-ABL-negative colony-forming cells in the peripheral blood. Particularly, IFN responders show increased numbers of normal hematopoietic cells. We have quantitatively analyzed progenitor cells in PBMNCs of IFN-treated patients by combining the clonogenic assay in semisolid medium with interphase fluorescent in situ hybridization (FISH). Thus, the identification is possible of the BCR-ABL status of colony-forming progenitor cells. In IFN-treated patients, the number of BCR-ABL-positive CFCs is considerably decreased and BCR-ABL-negative CFCs appear in the peripheral blood. We could show that after LTC for 35 days of the same PBMNCs on irradiated allogeneic normal stromal cells residual BCR-ABL sequence-positive CFCs were still present. In some cases the relative number of BCR-ABL sequence-positive CFCs was found to be increased after LTC. A minor proportion of blood samples from IFN-treated patients did not give rise to CFCs after LTC on allogeneic stromal cells (three of 10 patients). Inter- and intraindividual variations can be found with regard to loss or gain of BCR-ABL sequence-positive colonies after LTC. We conclude that early CML progenitor cells persist in the peripheral blood of IFN-treated patients and that a certain proportion may survive long-term culture.
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PMID:Does long-term culture favor normal clonogenic cells from interferon-treated patients with chronic myelogenous leukemia? 1023 67

The hallmark of chronic myelogenous leukemia (CML) is the Philadelphia (Ph) chromosome that fuses genetic sequences of the BCR gene on chromosome 22 with c-ABL sequences translocated from chromosome 9. BCR/ABL fusion proteins have a dysregulated protein tyrosine kinase (PTK) activity exerting a key role in malignant transformation. Targeting the tyrosine kinase activity of BCR/ABL or using agents capable of triggering apoptosis might represent attractive therapeutic approaches for ex vivo purging. AG957, a member of the tyrphostin compounds, exerts a selective inhibition of p210(BCR/ABL) tyrosine phosphorylation. We report here that preincubation of CML or normal CD34(+) cells with graded concentration of AG957 (1 to 100 micromol/L) resulted in a statistically significant, dose-dependent suppression of colony growth from multipotent, erythroid, and granulocyte-macrophage progenitors as well as the more primitive long-term culture-initiating cells (LTC-IC). However, AG957 doses causing 50% inhibition (ID50) of CML and normal progenitors were significantly different for multilineage colony-forming units (CFU-Mix; 12 v 64 micromol/L; P =.008), burst-forming unit-erythroid (BFU-E; 29 v 89 micromol/L; P =.004), colony-forming unit-granulocyte-macrophage (CFU-GM; 34 v 85 micromol/L; P =.004), and LTC-IC (43 v 181 micromol/L; P =.004). In 5 of 10 patients, analysis of BCR/ABL mRNA on single progenitors by reverse transcription-polymerase chain reaction showed that AG957 at 50 micromol/L significantly reduced the mean (+/-SD) percentage of BCR/ABL-positive progenitors (92% +/- 10% v 33 +/- 5%; P =.001). Because AG957 treatment resulted in significantly higher percentages of apoptotic cells (30% v 9%) in the BCR/ABL-transfected 32DLG7 cells as compared with 32D-T2/93 cells (BCR/ABL-negative), we investigated the combined effects of AG957 with the anti-Fas receptor (Fas-R) monoclonal antibody CH11 that triggers apoptosis. As compared with AG957 alone, the sequential treatment of CML CD34(+) cells with AG957 (1 micromol/L) and CH11 (1 microgram/mL) increased CFU-Mix, BFU-E, and CFU-GM growth inhibition by 1.6-fold, 3-fold, and 4-fold, respectively. In contrast, the treatment of normal CD34(+) cells with AG957 and CH11 failed to enhance AG957-induced colony growth inhibition. We conclude that (1) AG957 inhibits in a dose-dependent manner CML CD34-derived colony formation by both primitive LTC-IC as well as committed CFU-Mix, BFU-E, and CFU-GM; (2) this growth inhibition is associated with the selection of a substantial amount of BCR/ABL-negative progenitors; and (3) the antiproliferative effect of AG957 is dramatically increased by combining this compound with the anti-Fas-R antibody CH11. These data may have significant therapeutic applications.
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PMID:Effects of the tyrosine kinase inhibitor AG957 and an Anti-Fas receptor antibody on CD34(+) chronic myelogenous leukemia progenitor cells. 1033 7

Elevated leukotriene (LT)C(4) synthase activity was observed in peripheral blood granulocyte suspensions from patients with chronic myeloid leukemia (CML). Magnetic cell sorting (MACS) with CD16 monoclonal antibodies (mAbs), which were used to fractionate granulocytes from CML patients and healthy individuals, yielded highly purified suspensions of CD16(+) neutrophils. The purity of these cell fractions was verified by extensive morphologic examination. Reverse transcriptase-polymerase chain reaction (RT-PCR) analyses, demonstrating the absence of interleukin-4 messenger RNA (IL-4 mRNA), further confirmed the negligible contamination of eosinophils in these fractions. Notably, purified CML CD16(+) neutrophils from all tested patients transformed exogenous LTA(4) to LTC(4). These cells also produced LTC(4 )after activation with ionophore A23187 or the chemotactic peptide fMet-LeuPhe (N-formylmethionyl-leucyl-phenylalanine). Subcellular fractionation revealed that the enzyme activity was exclusively distributed to the microsomal fraction. Expression of LTC(4) synthase mRNA in CML CD16(+) neutrophils was confirmed by RT-PCR. Furthermore, Western blot analyses consistently demonstrated expression of LTC(4) synthase at the protein level in CML CD16(+) neutrophils, whereas expression of microsomal glutathione S-transferase 2 occurred occasionally. Expectedly, LTC(4) synthase activity or expression of the protein could not be demonstrated in CD16(+) neutrophil suspensions from any of the healthy individuals. Instead, these cells, as well as CML CD16(+) neutrophils, transformed LTA(4) to LTB(4). The results indicate that aberrant expression of LTC(4) synthase is a regular feature of morphologically mature CML CD16(+) neutrophils. This abnormality, possibly associated with malignant transformation, can lead to increased LTC(4) synthesis in vivo. Such overproduction may be of pathophysiological relevance because LTC(4 )has been demonstrated to stimulate proliferation of human bone marrow-derived myeloid progenitor cells. (Blood. 2000;95:1456-1464)
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PMID:Aberrant expression of active leukotriene C(4) synthase in CD16(+) neutrophils from patients with chronic myeloid leukemia. 1066 25

Monocyte-induced cell-cytotoxicity has been implicated in the mechanism of suppression of normal haematopoietic progenitors in chronic myeloid leukemia (CML). We examined here the in vitro effect of CML-derived and normal peripheral blood (PB) monocytes on short- and long-term cultured haematopoietic progenitor cells. Short-term coculture (5 days) of CML or normal monocytes with CML or normal peripheral blood mononuclear cells (PBMNC)/CD34+ cells as targets resulted in a significant inhibition of colony-forming cell (CFC) growth. Coculture conditioned medium (CCM) from 5-days cocultures of normal or CML CD14+ monocytes with CD34+ cells were likewise inhibitory to CFC. In 5-week long-term cocultures of monocytes in direct contact with normal bone marrow (BM) progenitors, CML monocytes reduced the proportion of long-term cultured CFC (LTC-CFC) significantly to 52% of the controls, while normal monocytes had a less pronounced inhibitory effect (89% of the controls) on LTC-CFC. Reduction of LTC-CFC was great when CML monocytes and target cells were separated by a transwell membrane as compared to control cultures in the absence of CD14+ cells (53.5 vs. 9%). CCM from 5-week cocultures of normal or CML CD14+ monocytes with CD34+ progenitors from bone marrow (BM) cells were also inhibitory to CFC. No difference in cytokine levels for TNF-alpha, IFN-gamma, G-CSF, IL-10, IL-6 was detectable between CML CD14+ CCM and control CCM derived from short- and long-term cocultures. Our results suggest that CML monocytes may play a role in the inhibition of normal haematopoiesis through a yet not defined soluble factor supporting the expansion of the malignant clone in CML.
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PMID:CD14+ peripheral blood mononuclear cells from chronic myeloid leukemia and normal donors are inhibitory to short- and long-term cultured colony-forming cells. 1073 4

In the majority of newly diagnosed patients with chronic myeloid leukaemia (CML), the bone marrow contains consistent numbers of normal Ph-negative surrogate stem cells (LTC-IC) which seem to decline rapidly with time. This is confirmed by mobilization studies showing that early after diagnosis is the optimal time to collect Ph-negative progenitor to be utilized for restoring Ph-negative haematopoiesis. In the marrow of the majority of CML patients at diagnosis Ph-positive LTC-IC are found at a lower frequency than Ph-negative LTC-IC and, unexpectedly, they do not show a tendency to increase with time as long as patients remain in chronic phase. Therefore, the decline of normal haematopoiesis does not seem related to a parallel increase in Ph-positive stem cells.
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PMID:Normal and leukaemic haematopoiesis in bone marrow and peripheral blood of patients with chronic myeloid leukaemia. 1100 Sep 93

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder in which there is a deregulated amplification of CML progenitors at intermediate stages of their differentiation along the myeloid, erythroid and megakaryocyte pathways. Such cell populations are routinely quantified using standard in vitro colony-forming cell (CFC) assays. The excessive production of leukemic CFC that is seen in most CML patients at diagnosis may be explained at least in part by their increased proliferative activity. An anomalous cycling behavior in vivo has also been found to extend to more primitive CML progenitor populations detectable as long-term culture-initiating cells (LTC-IC). Although the molecular basis of these changes in CML progenitor regulation is not fully understood at the level of the primitive CFC compartment, a selective inability of CML progenitors to be inhibited by certain -C-C-type chemokines has been demonstrated. Failure of the CML stem cell compartment to expand in vivo at the same rate as later progenitor cell types may be explained by their unique additional possession of an intrinsically upregulated probability of differentiation. Such a mechanism would be consistent with the observed loss of LTC-IC activity by CML cells incubated in vitro under conditions that sustain or expand normal LTC-IC populations. Initial clinical studies undertaken at our center established the feasibility of exploiting the differential behavior of primitive normal and CML cells in vitro as a potential purging strategy for reducing the leukemic stem cell content of CML marrow autografts. The results of a larger, second trial now in progress on a group of unselected patients are encouraging. Future studies of nonobese diabetic/severe-combined immunodeficiency mice engrafted with CML cells should provide another useful preclinical model for evaluating treatments that may more effectively eradicate the neoplastic clone in vivo.
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PMID:Differences between normal and CML stem cells: potential targets for clinical exploitation. 1101 49

Over the past 15 years, important developments in the cell and molecular biology of chronic myeloid leukemia (CML) have produced significant changes in understanding of the pathophysiology of the disease. In this article we deal essentially with cell biology as a basis for autografting. The most important achievements of the past years are summarized. There is an exodus of normal hematopoietic cells from bone marrow at the beginning of leukemic invasion. Normal early hematopoietic progenitors (LTC-IC) are preserved at diagnosis and are much more frequent than the Ph-positive counterpart; however, PH-negative LTC-IC rapidly decline with time without a parallel increase of PH-positive LTC-IC. Therefore, probably leukemic stem cells are much fewer than previously thought. Nevertheless, a frequency of Ph-positive KTC-IC of 1/5 10(6) mononuclear cells corresponds with a remarkable tumor burden. Interferon preserves Ph-progenitors in cytogenic remitters. From these studies a new strategy for autografting patients with CML has been developed and is described here. Questions raised by these new techniques are also addressed.
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PMID:Biologic and clinical aspects of autologous stem cell transplantation with mobilized peripheral blood cells in chronic myelogenous leukemia. 1112 36

Several groups have shown that Ph-progenitors reappear in LTC of CML bone marrow or PBMNC when the cell preparations were derived from newly diagnosed Ph-positive patients or after induction chemotherapy. We have tested the hypothesis whether LTC may further decrease CML progenitors if the cells to be cultured were from IFN-treated patients. In our experiments, PBMNC were cultured from 7 IFN- and 5 HU-treated patients in stable chronic phase of the disease, and from 9 patients at diagnosis. Progenitor cells in PBMNC were quantitatively analyzed before and after 35 days of LTC by combining the clonogenic assay in semisolid medium with dual-color interphase FISH for identification of the BCR/ABL status of colony-forming progenitor cells. A median of 22 colonies (range 7-88) before and 30 colonies (5-71) after LTC were analyzed per patient. Our results show that the number of BCR/ABL-positive CFC before and after LTC was approximately the same. This was independent of IFN or HU therapy. In the IFN group there were 58% (median) BCR/ABL-positive CFC before and 54% (median) after LTC of PBMNC. In the HU group, 80% of CFC were BCR/ABL-positive before and 85% after LTC. A complete elimination of BCR/ABL-positive cells was not achieved. We conclude that CML early progenitors in PBMNC of IFN-treated CML patients may survive LTC.
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PMID:Interferon-alpha-treated patients with chronic myelogenous leukemia show BCR/ABL-positive peripheral blood progenitor cells surviving long-term culture. 1114 Aug 58

The objective of this study was to analyze the mobilization kinetics of normal (BCR-ABL(neg)) and malignant (BCR-ABL(pos)) progenitor cells using a new, low toxic, out-patient-based mobilization regimen for Philadelphia chromosome-positive (Ph(pos)) chronic myelogenous leukemia (CML) patients. High doses of hydroxyurea (HD-HU, 3.5 g/m(2) per day, orally for 7 days) followed by granulocyte colony-stimulating factor (G-CSF) (10 microg/kg subcutaneously) were administered to 11 newly diagnosed CML patients. Each apheresis product (n = 30) was individually analyzed for the number and genotype of mature colony-forming cells (CFC) and primitive long-term culture initiating cells (LTC-IC), respectively, by reverse transcription polymerase chain reaction (RT-PCR) of individual colonies. Sufficient numbers of CD34(+) cells/kg bodyweight (BW) could easily be obtained in all patients (median, 15 x 10(6)/kg BW per patient) with a median number of three aphereses performed per patient (range 2-4). Almost each apheresis itself (25/30) contained > or =2 x 10(6) CD34(+) cells/kg BW. All patients with low and intermediate Sokal risk indices (9/11) mobilized primarily BCR-ABL(neg) LTC-IC (median 92%, range 47-100) and CFC (median 89%, range 57-100). Moreover, the mean percentage of BCR-ABL(neg) CFC and LTC-IC in the various apheresis products in these patients did not change throughout the entire time of hematopoietic regeneration. The toxicity of the mobilization procedure was low. Side effects were mild erythema in 8/11 and oral mucositis in 3/11 patients. Overall, the low toxicity of this regimen, together with the fact that sufficient BCR-ABL(neg) progenitors can be collected throughout the entire period of hematopoietic regeneration, renders this mobilization regimen particularly attractive for the collection of BCR-ABL(neg) progenitors in early chronic phase of Ph(pos) CML.
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PMID:High-dose hydroxyurea plus G-CSF mobilize BCR-ABL-negative progenitor cells (CFC, LTC-IC) into the blood of newly diagnosed CML patients at any time of hematopoietic regeneration. 1198

The in vitro effect of bestatin on Philadelphia (Ph) chromosome positive chronic myeloid leukemia (CML) was investigated using mature clonogenic cells and primitive stem cells derived from long-term culture-initiating cells (LTC-ICs). Individual colonies were grown in methycellulose culture (clonogenic cells) and after 5 weeks, LTC (colonies derived from LTC-ICs) were individually isolated. DNA isolated from these clonogenic colonies was studied by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis to detect BCR/ABL mRNA transcripts b3a2 and b2a2. At the mature hematopoietic progenitor cell level, almost all (20/21) colonies, including both erythroid and myeloid progenitors, were leukemic, i.e. BCR/ABL mRNA positive. Although normal progenitors were able to grow in the presence of bestatin, even at the most primitive progenitor cell level (LTC-ICs), the number of leukemic clones gradually decreased. Furthermore, bestatin suppressed the outgrowth of leukemic clones more frequently than control LTC without any effect on the growth of normal clones. These results indicate that bestatin, at levels that can be obtained by per os administration clinically, suppresses only Ph-positive leukemic clones without affecting normal hematopoiesis. Based on these results, we suggest that bestatin has the potential to provide another treatment for patients with CML.
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PMID:Bestatin selectively suppresses the growth of leukemic stem/progenitor cells with BCR/ABL mRNA transcript in patients with chronic myelogeneous leukemia. 1278 6


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