Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A series of adenosine deaminase (ADA) retroviral vectors were designed and constructed with the goal of improved performance over the PA317/LASN vector currently used in clinical trials. First, the bacterial selectable-marker neomycin phosphotransferase (neo) gene was removed to create a "simplified" vector. Second, the Moloney murine leukemia virus long terminal repeat (LTR) promoter used for ADA expression was replaced with either the myeloproliferative sarcoma virus (MPSV) or SL3-3 LTR. Supernatant from each ADA vector was used to transduce ADA-deficient (ADA-) B- and T-cell lines as well as primary peripheral blood mononuclear cells (PBMC) from an ADA- severe combined immunodeficiency patient. Total ADA enzyme activity and ADA activity per integrant in the transduced cells demonstrated that the MPSV LTR splicing vector design provided the highest level of ADA expression per cell. This ADA(MPSV) vector was then tested in packaging cell lines containing either the gibbon ape leukemia virus envelope (PG13 cells), the murine amphotropic envelope (FLYA13 cells), or the feline endogenous virus RD114 envelope (FLYRD18 cells). The results indicate that FLYRD18/ADA(MPSV), a simplified ADA retroviral vector with the MPSV LTR, provides a 17-fold-higher level of ADA expression in human lymphohematopoietic cells than the PA317/LASN vector currently in use.
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PMID:Development of improved adenosine deaminase retroviral vectors. 949 26

The oncogenic BCR/ABL protein protects hematopoietic cells from apoptosis induced by growth factor deprivation, but the mechanisms are only partially understood. A BCR/ABL mutant lacking amino acids 176-426 in the BCR domain (p185DeltaBCR) failed to protect interleukin 3-deprived 32Dcl3 myeloid precursor cells from apoptosis, although it possessed tyrosine kinase activity and was capable of activating the Ras-Raf-MAP kinase pathway. Compared to p185 wild-type transfectants, p185DeltaBCR-transfected cells showed markedly reduced levels of Bcl-2 and expressed the hypophosphorylated, proapoptotic form of BAD. Bcl-2 expression in the mitochondrial fraction of p185DeltaBCR cells was also markedly diminished and mitochondrial RAF was undetectable. In p185DeltaBCR cells transfected with a mitochondria-targeted, constitutively active RAF (M-Raf) BAD was expressed in the hyperphosphorylated form and released from the mitochondria into the cytosol. p185DeltaBCR/M-Raf-transfected cells were completely resistant to apoptosis induced by growth factor deprivation in vitro. Moreover, constitutive expression of dominant-negative M-Raf (K375W) enhanced the susceptibility of 32Dcl3 cells expressing wild-type BCR/ABL to apoptosis. In severe combined immunodeficiency (SCID) mice, p185DeltaBCR/M-Raf double transfectants were leukemogenic, whereas cells expressing only p185DeltaBCR showed no leukemogenic potential. Together, these data support the existence of a BCR/ABL-dependent pathway that leads to expression of an active RAF in the mitochondria and promotes antiapoptotic and leukemia-inducing effects of BCR/ABL.
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PMID:Expression of constitutively active Raf-1 in the mitochondria restores antiapoptotic and leukemogenic potential of a transformation-deficient BCR/ABL mutant. 962 59

The non-obese diabetic-severe combined immunodeficiency (NOD-SCID) mouse is a convenient host for human hematopoietic tissues and cells. Human fetal bone fragments engrafted subcutaneously in NOD-SCID mice sustain human hematopoiesis for several months. MS5 murine bone marrow stromal cells were transfected by electroporation with a plasmid containing the human interleukin-3 gene. As expected, stably transfected hu-IL3-MS5 cells supported human hematopoiesis in vitro more efficiently than MS5 cells. hu-IL3-MS5 cells were then injected intravenously into hu-NOD-SCID mice to test their ability to home to the mouse and/or human bone marrow, and to evaluate the role of hu-IL3 secretion on human hematopoiesis in vivo. hu-IL3 was detected in the mouse serum for up to an observation time of 8 weeks. hu-IL3-MS5 cells engrafted the bone marrow, spleen, liver and lungs of the mice but also the human bone graft. The presence of hu-IL3-MS5 cells in the human bone significantly stimulated local human hematopoiesis. This setting could be used to model the bone marrow homing of intravenously injected stromal cells or stromal cell precursors. The same experimental principle could also be applied in a therapeutic perspective to malignant human bone marrow hematopoiesis.
Leukemia 1998 Jul
PMID:Transplantation of stromal cells transduced with the human IL3 gene to stimulate hematopoiesis in human fetal bone grafts in non-obese, diabetic-severe combined immunodeficiency mice. 966

Bone marrow transplantation has been performed for almost 30 years in the Department of Paediatrics of the Leiden University Hospital. Major research efforts focussed on the accurate determination of the chimaerism and the immunological recovery of the graft recipient, and on the immunological interactions between donor and host cells. The results of our investigations and those of other groups in the field of bone marrow transplantation provided a lot of information on these topics, offering possibilities for improving the outcome of the patients by changing transplant procedures and developing novel preventive and therapeutic interventions. As was formerly shown in animal experiments, the conditioning of the graft recipient had to be tailored for the purposes of the bone marrow transplantation. It had to be either immunosuppressive, or space creating, or tumor eradicating, or a combination of these, in accordance with the original disease of the patient. It also became evident that the numbers of functional T lymphocytes remaining in the host and present in the graft had reciprocal effects on graft rejection (host-versus-graft) and graft-versus-host disease. Modification of the composition of the graft, e.g. by T-cell depletion, resulted in an increased rejection rate unless extra-immunosuppression was administered to the host. Vice versa, the occurrence and severity of graft-versus-host disease was very much dependent on HLA-matching between donor and recipient and on numbers of T cells in the graft. With regard to immune recovery after bone marrow transplantation, it was shown that the pretreatment of the host had to be adjusted to obtain engraftment of those cell lineages which were relevant for an adequate and complete immune competence of the host after bone marrow transplantation. This could nicely be illustrated by the relationship between B-cell engraftment and recovery of humoral immunity after HLA-haplo-identical bone marrow transplantation of young children, suffering from severe combined immunodeficiency disease. In later experiments our group showed that is was feasible to transfer specific immunological "memory" to vaccine antigens from donor to host by mature T cells in the graft and following priming of donor and host with the antigen prior to transplantation. Reversely, when T cells were taken out of the graft, reactivations of DNA-viruses such as CMV and EBV could be observed, frequently resulting in lethal infections. Also there was an increase of the frequency of leukaemia relapse after T-cell depleted bone marrow transplantation for leukaemia. In order to prevent these severe complications donor T-cell infusions have been tried with success, although also with an increase in occurrence and severity of graft-versus-host disease. Recent developments on the production ex vivo of virus-specific cytotoxic T cells and the transfer of these cells to the host, early after bone marrow transplantation, resulted in remarkable clinical effects. These observations open the way for further research, development and trials of adoptive immunotherapy for the prevention of leukaemia relapse after bone marrow transplantation of leukaemia patients. Also recently attention has been paid to the induction of microchimaerism with donor haemopoietic cells, following a relatively non-toxic one-day conditioning of the host, in order to attain a state of tolerance against a solid organ transplant. This possibly promising application of the presence of a blood cell chimaerism is at present under study in animal models.
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PMID:Allogeneic bone marrow transplantation: relation between chimaerism and immunity. 970 64

The establishment of an in vivo animal model system for infant acute lymphoblastic leukemia (ALL) would allow the testing of new agents against primary leukemic cells from infant ALL patients. We have demonstrated previously that growth of B-lineage leukemic cells in mice with severe combined immunodeficiency (SCID) was a significant prognostic factor for children with high risk ALL. We now have examined the significance of this prognostic variable for 13 infants with newly diagnosed ALL treated at participating institutions of the Children's Cancer Group (CCG). Chromosomal translocations were detected in 10/12 evaluated cases, including five with t(4;11), one each with t(7;9) and t(7;11), t(1;19), and t(9;22), and two with t(11;19). Twelve of the thirteen infants with ALL achieved remissions following induction chemotherapy. Primary leukemic cells from 8 of the 13 infants caused overt leukemia in SCID mice. Among these 8 SCID+ infants, 7 were CD10- and seven had cytogenetic or molecular evidence of an 11q23 rearrangement. Six of the 8 SCID+ infants have relapsed; only 2 remain in remission following chemotherapy or bone marrow transplant. However, among the 5 SCID- infants there were also two relapses. These data are suggestive of a poorer outcome for SCID+ infants, but larger numbers of patients must be analyzed to assess their statistical significance. In summary, we have established a SCID mouse model for human infant ALL that will be useful for 1) predicting short-term and long-term outcome of patients, 2) testing pharmacokinetics, efficacy, and toxicity of new agents, and 3) elucidating the in vivo mechanisms of chemotherapeutic drug resistance in infant ALL.
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PMID:Primary blasts from infants with acute lymphoblastic leukemia cause overt leukemia in SCID mice. 971 59

Attachment of human pre-B leukaemic cells to human or murine bone marrow stromal cells in vitro is largely mediated by the beta1 integrin VLA-4 binding to VCAM-1. Cells subsequently migrate within the stroma, a process also involving VLA-4. A variant of the pre-B acute lymphoblastic leukaemia cell line NALM-6, designated 4A1, lacking expression of VLA-4, was generated by radiation-induced mutagenesis followed by several rounds of negative selection with immunomagnetic beads, fluorescence activated cell sorting and clonal expansion. In vitro assays using 4A1 cells showed reduced binding to, and migration under, the murine stromal line M2-10B4. Sublethally irradiated mice (n=19) with severe combined immunodeficiency were injected intravenously with NALM-6 cells. Animals developed signs of leukaemia with hind-limb paralysis at a median of 30 d (95% confidence interval 28-30). Although there were no gross abnormal findings at autopsy, histological analysis revealed extensive marrow replacement and focal liver infiltration with leukaemic blasts, which were confirmed to be of human origin by flow cytometry. 12 mice were injected with a similar number of cells from the VLA-4-negative variant cell line 4A1. Six mice developed signs of leukaemia after 43-74d, with the remaining six being free of signs of disease after > 100d (P<0.001). Mice in this group with leukaemia had a lower incidence of hind-limb paralysis and less leukaemic infiltration in the marrow, but in some cases had large tumour nodules elsewhere. After a single 500 microg intraperitoneal injection of anti-murine VCAM-1 monoclonal antibody (MK2.7), five additional mice were injected with an identical number of wild-type (VLA-4+) NALM-6. All animals developed signs of leukaemia after a similar period to those injected with wild-type NALM-6 only. These results demonstrate that the beta1 integrin VLA-4 is involved in the engraftment of the pre-B-cell leukaemic cell line NALM-6 in SCID mice, although the interaction with VCAM-1 is unlikely to be the sole explanation.
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PMID:VLA-4 is involved in the engraftment of the human pre-B acute lymphoblastic leukaemia cell line NALM-6 in SCID mice. 975 59

To understand the mechanisms and identify novel approaches to overcoming retinoic acid (RA) resistance in acute promyelocytic leukaemia (APL), we established the first human RA-resistant APL model in severe combined immunodeficiency (SCID) mice. UF-1 cells, an RA-resistant APL cell line established in our laboratory, were transplanted into human granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing SCID (hGMTg SCID) mice and inoculated cells formed subcutaneous tumours in all hGMTg SCID mice, but not in the non-transgenic control SCID mice. Single-cell suspensions (UF-1/GMTg SCID cells) were similar in morphological, immunological, cytogenetic and molecular genetic features to parental UF-1 cells. All-trans RA did not change the morphological features of cells or their expression of CD11b. RA did not alter the growth curve of cells as determined by MTT assay, suggesting that UF-1/GMTg SCID cells are resistant to RA. These results demonstrate that this is the first RA-resistant APL animal model that may be useful for investigating the biology of this myeloid leukaemia in vivo, as well as for evaluating novel therapeutic approaches including patients with RA-resistant APL.
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PMID:Establishment of a retinoic acid-resistant human acute promyelocytic leukaemia (APL) model in human granulocyte-macrophage colony-stimulating factor (hGM-CSF) transgenic severe combined immunodeficiency (SCID) mice. 976 78

Acute myeloid leukemia (AML) occurs as the result of malignant transformation in a hematopoietic progenitor cell, which proliferates to form an accumulation of AML blasts. Only a minority of these AML cells are capable of proliferation in vitro, suggesting that AML cells may be organized in a hierarchy, with only the most primitive of these cells capable of maintaining the leukemic clone. To further investigate this hypothesis, we have evaluated a strategy for purifying these primitive cells based on surface antigen expression. As an in vitro endpoint, we have determined the phenotype of AML progenitor cells which are capable of producing AML colony-forming cells (CFU) for up to 8 weeks in suspension culture (SC) and compared the phenotype with that of cells which reproduce AML in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice. AML cells were fluorescence-activated cell sorted (FACS) for coexpression of CD34 and CD71, CD38, and/or HLA-DR and the subfractions were assayed in vitro and in vivo at various cell doses to estimate purification. While the majority of primary AML CFU lacked expression of CD34, most cells capable of producing CFU after 2 to 8 weeks in SC were CD34(+)/CD71(-). HLA-DR expression was heterogeneous on cells producing CFU after 2 to 4 weeks. However, after 6 to 8 weeks in SC, the majority of CFU were derived from CD34(+)/HLA-DR- cells. Similarly, the majority of cells capable of long-term CFU production from SC were CD34(+)/CD38(-). Most cells that were capable of engrafting NOD/SCID mice were also CD34(+)/CD71(-) and CD34(+)/HLA-DR-. Engraftment was not achieved with CD34(+)/CD71(+) or HLA-DR+ subfractions, however, in two patients, both the CD34(+) and CD34(-) subfractions were capable of engrafting the NOD/SCID mice. A three-color sorting strategy combining these antigens allowed approximately a 2-log purification of these NOD/SCID leukemia initiating cells, with engraftment achieved using as few as 400 cells in one experiment. Phenotyping studies suggest even higher purification could be achieved by combining lack of CD38 expression with the CD34(+)/CD71(-) or CD34(+)/HLA DR- phenotype. These results suggest that most AML cells capable of long-term proliferation in vitro and in vivo share the CD34(+)/CD71(-)/HLA-DR- phenotype with normal stem cells. Our data suggests that in this group of patients the leukemic transformation has occurred in a primitive progenitor, as defined by phenotype, with some degree of subsequent differentiation as defined by functional assays.
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PMID:Most acute myeloid leukemia progenitor cells with long-term proliferative ability in vitro and in vivo have the phenotype CD34(+)/CD71(-)/HLA-DR-. 983 39

Contemporary intensive therapies are effective for the majority of pediatric T-lineage acute lymphoblastic leukemia (ALL) patients, thus current challenge is to identify patients who may benefit from alternative treatment modalities. Previously, we demonstrated that human leukemic cell growth in the severe combined immunodeficiency (SCID) mouse was a significant prognostic factor for very high risk B-lineage ALL patients. In the current report we show that primary leukemic cells from 24 of 88 (27%) T-lineage ALL patients (SCID+) caused histopathologically detectable leukemia in SCID mice. These SCID+ patients were similar to SCID- (n = 64) patients with respect to virtually all presenting features, including age, sex, race, and leukocyte count. Growth of primary leukemic cells in SCID mice was not a significant predictor of outcome for the aggregate population of T-lineage ALL patients. Two-year event-free survival (EFS) outcomes for SCID+ patient and SCID- patients were 76.2% (SD = 5.6%) and a 64.0% (SD = 10.4%; p = 0.20). Overall survival also was similar between the two groups (p = 0.36). Among the subset of patients with M1 or M2 marrow status by day 7 of induction chemotherapy (rapid early responders), those who were SCID+ had poorer outcomes than those who were SCID-, with a 2-year EFS of 68.4% (SD = 11.9%) vs. 85.7% (SD = 6.0%) and relative hazard rate of 3.06 (p = 0.06). These data suggest that leukemic cell growth in SCID mice may identify a subset of T-lineage ALL patients who are at higher risk for relapse despite achieving a rapid early response to induction chemotherapy.
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PMID:Prognostic significance of T-lineage leukemic cell growth in SCID mice: a Children's Cancer Group study. 1004 20

Signal transducer and activator of transcription (STAT)5 is constitutively activated in BCR/ ABL-expressing cells, but the mechanisms and functional consequences of such activation are unknown. We show here that BCR/ABL induces phosphorylation and activation of STAT5 by a mechanism that requires the BCR/ABL Src homology (SH)2 domain and the proline-rich binding site of the SH3 domain. Upon expression in 32Dcl3 growth factor-dependent myeloid precursor cells, STAT5 activation-deficient BCR/ABL SH3+SH2 domain mutants functioned as tyrosine kinase and activated Ras, but failed to protect from apoptosis induced by withdrawal of interleukin 3 and/or serum and did not induce leukemia in severe combined immunodeficiency mice. In complementation assays, expression of a dominant-active STAT5B mutant (STAT5B-DAM), but not wild-type STAT5B (STAT5B-WT), in 32Dcl3 cells transfected with STAT5 activation-deficient BCR/ABL SH3+SH2 mutants restored protection from apoptosis, stimulated growth factor-independent cell cycle progression, and rescued the leukemogenic potential in mice. Moreover, expression of a dominant-negative STAT5B mutant (STAT5B-DNM) in 32Dcl3 cells transfected with wild-type BCR/ABL inhibited apoptosis resistance, growth factor-independent proliferation, and the leukemogenic potential of these cells. In retrovirally infected mouse bone marrow cells, expression of STAT5B-DNM inhibited BCR/ABL-dependent transformation. Moreover, STAT5B-DAM, but not STAT5B-WT, markedly enhanced the ability of STAT5 activation-defective BCR/ABL SH3+SH2 mutants to induce growth factor-independent colony formation of primary mouse bone marrow progenitor cells. However, STAT5B-DAM did not rescue the growth factor-independent colony formation of kinase-deficient K1172R BCR/ABL or the triple mutant Y177F+R522L+ Y793F BCR/ABL, both of which also fail to activate STAT5. Together, these data demonstrate that STAT5 activation by BCR/ABL is dependent on signaling from more than one domain and document the important role of STAT5-regulated pathways in BCR/ABL leukemogenesis.
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PMID:Signal transducer and activator of transcription (STAT)5 activation by BCR/ABL is dependent on intact Src homology (SH)3 and SH2 domains of BCR/ABL and is required for leukemogenesis. 1020 40


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