UNIPROT:P10415 - FACTA Search

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Query: UNIPROT:P10415 (Bcl-2)
33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fas antigen (Fas Ag; CD95) is a cell surface molecule that can mediate apoptosis. Bcl-2 is a cytoplasmic molecule that prolongs cellular survival by inhibiting apoptosis. To investigate the role of both molecules in hematopoiesis, we evaluated the expression of Fas Ag and Bcl-2 on CD34+ hematopoietic progenitor cells expanded in vitro. CD34+ cells isolated from bone marrow were cultured in iscove's modified Dulbecco's medium supplemented with 10% fetal calf serum, 1% bovine serum albumin, 50 ng/mL stem cell factor, 50 ng/mL interleukin-3 (IL-3), 50 ng/mL IL-6, 100 ng/mL granulocyte colony-stimulating factor, and 3 U/mL erythropoietin for 7 days. Colony-forming unit of granulocytes/macrophages (CFU-GM) and burst-forming unit of erythroids (BFU-E) were expanded 6.9-fold and 8.8-fold in number at day 5 of culture, respectively. Freshly isolated CD34+ cells did not express Fas Ag, whereas approximately half of them expressed Bcl-2. CD34+ cells cultured with hematopoietic growth factors gradually became positive for Fas Ag and rapidly lost Bcl-2 expression. Furthermore, apoptosis was induced in the cultured CD34+ population when anti-Fan antibody (IgM; 1 microgram/mL) was added, as shown by significant decrease in the number of viable cells, morphologic changes, induction of DNA fragmentation, and significant decrease in the number of clonogenic progenitor cells including CFU. GM and BFU-E. These results indicate that functional expression of Fas Ag is induced on CD34+ cells expanded in vitro in the presence of hematopoietic growth factors. Induction of Fas Ag and downregulation of Bcl-2 may be expressed as part of the differentiation program of hematopoietic cells and may be involved in the regulation of hematopoiesis.
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PMID:In vitro expansion of hematopoietic progenitor cells induces functional expression of Fas antigen (CD95). 887 83

Flt3/flk-2 ligand (flt3-L) is a potent costimulator of normal bone marrow (BM) myeloid progenitors. Flt3-L is produced by BM stromal cells and its receptor is expressed in the majority of acute myeloid leukemia (AML) cases. Therefore, flt3-L may play a role in the paracrine and/or autocrine loops sustaining leukemic cell growth. We evaluated the effects of recombinant human flt3-L on proliferation, apoptosis, and Bcl-2 and Bax expression in primary AML cells and compared them with those of stem cell factor (SCF). Mononuclear BM cells from patients with newly diagnosed AML were cultured in serum-free conditions with flt3-L, SCF, granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage-colony-stimulating factor (GM-CSF) alone and in combination. In 9 of 10 samples, flt3-L significantly increased [3H]thymidine uptake (geometric mean stimulation index, 7.5; range, 2.4 to 41.5). Flt3-L also increased the number of AML blast colonies by 126% (range, 61% to 181%). In these 9 samples, flt3-L significantly enhanced the proliferative response triggered by G-CSF or GM-CSF. Flt3-L prevented apoptosis in AML blasts. It reduced the number of apoptotic cells by 36% +/- 3.9% compared with control cultures. Combining flt3-L with G-CSF or GM-CSF doubled the antiapoptotic effect. Cellular Bcl-2 and Bax levels were determined separately for apoptotic and nonapoptotic cells by flow cytometry. Cells undergoing spontaneous apoptosis had low Bcl-2 and high Bax levels, whereas nonapoptotic cells had high Bcl-2 and low Bax levels. Flt3-L alone or in combination with G-CSF or GM-CSF did not upregulate Bcl-2. However, Bax expression decreased in viable cells in the presence of these cytokines and the lowest level was achieved when a combination of flt3 and GM-CSF was used. Proliferative and viability effects of flt3-L were similar to those of SCF. Our results demonstrate that flt3-L acts as a stimulatory factor for primary AML cells. The antiapoptotic effects of flt3-L or its combinations with G-CSF or GM-CSF correlate with their ability to prevent upregulation of Bax.
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PMID:Flt3 ligand stimulates proliferation and inhibits apoptosis of acute myeloid leukemia cells: regulation of Bcl-2 and Bax. 891 65

Ineffective hematopoiesis with associated cytopenias and potential evolution to acute myeloid leukemia (AML) characterize patients with myelodysplastic syndrome (MDS). We evaluated levels of apoptosis and of apoptosis-related oncoproteins (c-Myc, which enhances, and Bcl-2, which diminishes apoptosis) expressed within CD34+ and CD34- marrow cell populations of MDS patients (n = 24) to determine their potential roles in the abnormal hematopoiesis of this disorder. Marrow cells were permeabilized and CD34+ and CD34- cells were separately analyzed by FACS to detect: (1) a subdiploid (sub-G1) DNA population, and (2) expression of Bcl-2 and c-Myc oncoproteins. Within the CD34+ subset, a significantly increased percentage of cells demonstrated apoptotic/sub-G1 DNA content in early (ie. refractory anemia) MDS patients compared with normal individuals and AML patients (mean values: 9.1% > 2.1% > 1.2%). Correlated with these findings, the ratio of expression of c-Myc to Bcl-2 oncoproteins among CD34+ cells was significantly increased for MDS patients compared to those from normal and AML individuals (mean values: 1.6 > 1.2 > 0.9). Bcl-2 and c-Myc oncoprotein levels were maturation stage-dependent, with high levels expressed within CD34+ marrow cells, decreasing markedly with myeloid maturation. Treatment of seven MDS patients with the cytokines granulocyte colony-stimulating factor plus erythropoietin was associated with decreased levels of apoptosis within CD34+ marrow cells and may contribute to the enhanced hematopoiesis in vivo that was shown. These findings are consistent with the hypothesis that altered balance between cell-death (eg, c-Myc) and cell-survival (eg, Bcl-2) programs were associated with the increased degrees of apoptosis present in MDS hematopoietic precursors and may contribute to the ineffective hematopoiesis in this disorder, in contrast to decreased apoptosis and enhanced leukemic cell survival in AML.
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PMID:Altered oncoprotein expression and apoptosis in myelodysplastic syndrome marrow cells. 894 64

Interleukin 3 (IL-3)-dependent 32D.3 myeloid cells are an attractive model system for the analysis of hematopoietic cell growth, differentiation, and apoptosis. In these cells, E2F-3, E2F-4, and DP-1 are regulated by both IL-3 and granulocyte colony-stimulating factor (G-CSF), whereas E2F-1 was expressed at low levels and was not regulated by either cytokine. E2F-2 and E2F-5 were not detectable. To examine phenotypes associated with the loss of normal cell cycle regulation by pRb, we established E2F-1- and E2F-3-overexpressing cell lines. In contrast to E2F-1, E2F-3 overexpression did not accelerate apoptosis or promote S-phase entry in the absence of IL-3, demonstrating that they are not functionally redundant. In addition, when cells were cultured in G-CSF to stimulate granulocytic differentiation, E2F-1 overexpression overrode survival functions provided by G-CSF and serum and induced apoptosis. In contrast, cells overexpressing E2F-3 exhibited normal granulocytic differentiation. Bcl-2 coexpression blocked E2F-1-induced apoptosis in the presence of G-CSF. However, these cells were blocked in the granulocytic differentiation program at the metamyelocyte stage and remained dependent on G-CSF for continuous culture. Cells overexpressing both E2F-1 and Bcl-2 exhibited slowed but continuous cell cycling in the absence of IL-3 until they eventually succumbed to apoptosis. Therefore, E2F-1, but not E2F-3, can temporally replace the requirement for growth factors to promote cell cycle progression, and in terminally differentiating cells, this leads to a block in differentiation and induction of apoptosis.
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PMID:E2F-1 and E2F-3 are functionally distinct in their ability to promote myeloid cell cycle progression and block granulocyte differentiation. 943 89

P39/Tsugane is a myelomonocytoid cell line derived from a patient with myelodysplastic syndrome (MDS). The cells readily undergo apoptosis in response to various agents, and the cell line has been suggested as a useful model to study apoptosis in MDS. The aims of the present study were to assess differentiation and apoptosis induced with all-trans retinoic acid (ATRA) and etoposide, to characterize the mode of apoptosis in these two model systems, and to assess the influence of granulocyte colony-stimulating factor (G-CSF), which in combination with erythropoietin has been shown to inhibit apoptosis in MDS. ATRA induced differentiation and apoptosis in a concentration- and time-dependent manner. Differentiated cells were partially rescued (by 50%) from apoptosis with G-CSF. Etoposide induced apoptosis in a concentration- and time-dependent manner, but no signs of preceding maturation or G-CSF rescue were detected. ATRA- and etoposide-induced apoptosis were both mediated through the caspase pathway and were partially blocked with the general caspase inhibitor zVAD-fmk. Simultaneous treatment with G-CSF and zVAD-fmk additively blocked ATRA-induced apoptosis. However, the two pathways differed in terms of substrate cleavage during apoptosis. ATRA-induced apoptosis caused actin cleavage, which was not affected by G-CSF, and Bcl-2 downregulation. Etoposide induced a caspase-dependent cleavage of Bcl-2, while actin remained intact. The Fas system did not seem to play a major role in any of these apoptotic pathways. Our results may provide new tools to study the mechanisms of apoptosis in MDS.
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PMID:Two pathways of apoptosis induced with all-trans retinoic acid and etoposide in the myeloid cell line P39. 1042 9

Granulocyte colony-stimulating factor (G-CSF) is a cytokine that regulates the proliferation, differentiation and survival of cells in the granulocytic lineage. In this study, however, we found that G-CSF or interleukin-6 (IL-6) induced UF-1, a human acute promyelocytic leukemia cell line, into apoptosis that was confirmed by morphological features and DNA fragmentation. This rare response is demonstrated for the first time with human acute promyelocytic leukemia cell line. The apoptosis induced by G-CSF or IL-6 was not preceded by terminal differentiation characterized by morphological maturation, capability to reduce nitroblue tetrazolium, or surface CD11b expression. Interestingly, Western blot analysis revealed that the stimulation of UF-1 with either G-CSF or IL-6 resulted in excessive activation of both signal transducer and activator of transcription 3alpha (Stat3alpha) and Stat3beta. Furthermore, an additional 18 kDa Bax-related protein was expressed by the stimulation of G-CSF or IL-6, while Bcl-2 and Bcl-X proteins remained unchanged. These findings suggest that UF-1 may be a valuable tool in investigating the aberrant regulation of apoptosis, especially the Stat3 involvement in the mechanism of apoptosis induction.
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PMID:G-CSF induces apoptosis of a human acute promyelocytic leukemia cell line, UF-1: possible involvement of Stat3 activation and altered Bax expression. 1062 10

Sera from healthy subjects receiving recombinant human granulocyte colony-stimulating factor (rHuG-CSF) to mobilize CD34(+) peripheral blood progenitors (PBPC) have been recently shown to induce unresponsiveness of allogeneic lymphocytes to mitogenic challenge. In the present investigation, the effects of rHuG-CSF on the early stages of lymphocyte activation-induced apoptosis and on lymphocyte cell cycle entry were evaluated. Sera were obtained from HLA-identical donors receiving rHuG-CSF to mobilize CD34(+) PBPC for allogeneic transplantation. Normal peripheral blood mononuclear cells (PBMC) were challenged with phytohemagglutinin (PHA) in the presence of serum collected before (preG) or after rHuG-CSF administration (postG). Mitochondrial function, that is, incorporation of 3,3'-dihexyloxacarbocyanine iodide [DiOC(6)(3)] and generation of reactive oxygen species (ROS) as well as expression of c-Myc and Bcl-2 family members (Bcl-2, Bcl-X(L), Bax) were evaluated by multiparameter flow cytometry. The activation-induced fragmentation of genomic DNA was detected by highly sensitive LM-PCR assay.CD4(+)DiOC(6)(3)(low) and CD8(+)DiOC(6)(3)(low) T lymphocytes increased and reached 32% (range 27%-38%) and 20% (range 15%-23%) of circulating T cells, respectively, on day 4 of rHuG-CSF administration. Hypergeneration of ROS could be demonstrated in 65% (range 58%-82%) of CD4(+) T lymphocytes and in 0.4% (range 0.2%-0. 8%) of circulating CD8(+) T cells. rHuG-CSF determined no alteration of mitochondrial function if added to allogeneic PBMC in vitro, thus suggesting indirect effects mediated by soluble factors; on the contrary, when PBMC were challenged with PHA in the presence of postG serum, both perturbation of mitochondrial transmembrane potential (Deltapsi(m)) and hypergeneration of ROS were induced, and lymphocytes were predominantly arrested in a G(0) -like phase of the cell cycle and displayed genomic DNA fragmentation. Interestingly, the preincubation of PBMC with a blocking antibody directed against CD95 abrogated the perturbation of lymphocyte Deltapsi(m), suggesting that the CD95 signaling pathway might play a role in the induction of apoptosis after PHA stimulation in the presence of postG serum. Moreover, Bax protein was overexpressed in postG (median fluorescence intensity = 180, range 168-186) compared with preG cultures (median fluorescence intensity = 75, range 68-80; p < 0.01), while no differences in Bcl-2, Bcl-X(L), and c-Myc staining intensity were observed. Our findings demonstrate a humoral-mediated rHuG-CSF-induced dissipation of lymphocyte mitochondrial Deltapsi(m); these effects might be mediated by Bax overexpression, with imbalance between apoptosis-promoting and apoptosis-inhibiting Bcl-2 family members and with subsequent induction of mitochondrial permeability transition. Whether immune dysfunction will favorably impact on incidence and severity of acute graft vs host disease after allogeneic PBPC transplantation remains to be determined.
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PMID:Granulocyte colony-stimulating factor perturbs lymphocyte mitochondrial function and inhibits cell cycle progression. 1088 Jul 47

The short life span of granulocytes, which limits many inflammatory responses, is thought to be influenced by the Bcl-2 protein family, death receptors such as CD95 (Fas/APO-1), stress-activated protein kinases such as p38 mitogen-activated protein kinase (MAPK), and proinflammatory cytokines like granulocyte colony-stimulating factor (G-CSF). To clarify the roles of these various regulators in granulocyte survival, we have investigated the spontaneous apoptosis of granulocytes in culture and that induced by Fas ligand or chemotherapeutic drugs, using cells from normal, CD95-deficient lpr, or vav-bcl-2 transgenic mice. CD95-induced apoptosis, which required receptor aggregation by recombinant Fas ligand or the membrane-bound ligand, was unaffected by G-CSF treatment or Bcl-2 overexpression. Conversely, spontaneous and drug-induced apoptosis occurred normally in lpr granulocytes but were suppressed by G-CSF treatment or Bcl-2 overexpression. Although activation of p38 MAPK has been implicated in granulocyte death, their apoptosis actually was markedly accelerated by specific inhibitors of this kinase. These results suggest that G-CSF promotes granulocyte survival largely through the Bcl-2-controlled pathway, whereas CD95 regulates a distinct pathway to apoptosis that is not required for either their spontaneous or drug-induced death. Moreover, p38 MAPK signaling contributes to granulocyte survival rather than their apoptosis.
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PMID:Fas ligand, Bcl-2, granulocyte colony-stimulating factor, and p38 mitogen-activated protein kinase: Regulators of distinct cell death and survival pathways in granulocytes. 1103 12

Busulfan is an alkylating agent currently used in the myeloablative conditioning regimen before stem cell transplantation. Its mechanism of action is not fully understood, nor the reason for its narrow therapeutic window. We studied the pharmacodynamics of busulfan in an in vitro cell line model, allowing us to evaluate the effects of various doses and exposure times on clonogeneic capacity, proliferation and apoptosis. Cells were incubated with busulfan in concentrations ranging from 10 to 100 microg/ml for 2, 4 or 8 h, then washed and cultured in busulfan-free medium for 72 h. Area under the concentration-time curve (AUC) was estimated by using the trapezoidal rule from different concentrations and times of incubation. In all assays busulfan affected the cells in an AUC-dependent manner. Induced changes in the biological parameters studied appeared at different time points after exposure to busulfan stopped. Thus, the decrease in proliferation and clonogenic capacity preceded cell cycle arrest in G2 phase and development of apoptosis, implying that apoptosis is a secondary event to interruption of vital metabolic processes. Biochemically, apoptotic changes were typical for chemotherapy-induced apoptosis with caspase activation, cleavage of Bcl-2 and PARP proteins, while cleavage of actin was not observed. Cells were rescued from apoptosis with a general caspase inhibitor ZVAD-fmk, but not with granulocyte colony-stimulating factor (G-CSF). Our results add new information about busulfan pharmacodynamics and mechanisms underlying the cytotoxic effect of the drug.
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PMID:The pharmacodynamic effect of busulfan in the P39 myeloid cell line in vitro. 1148 May 66

Overexpression of Bcl-2 is a potential mechanism for chemoresistance in acute leukemia and has been associated with unfavorable clinical outcome. We hypothesized that down-regulation of Bcl-2 would restore chemosensitivity in leukemic cells. To test this hypothesis, we performed a phase 1 study of G3139 (Genasense, Genta, Berkeley Heights, NJ), an 18-mer phosphorothioate Bcl-2 antisense, with fludarabine (FL), cytarabine (ARA-C), and granulocyte colony-stimulating factor (G-CSF) (FLAG) salvage chemotherapy in patients with refractory or relapsed acute leukemia. Twenty patients with refractory or relapsed acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) were enrolled. G3139 was delivered by continuous infusion on days 1 to 10. FLAG chemotherapy was administered on days 5 to 10. Common side effects of this combination included fever, nausea, emesis, electrolyte imbalance, and fluid retention that were not dose limiting. Plasma pharmacokinetics of G3139 demonstrated steady-state concentration (Css) within 24 hours. Of the 20 patients, 9 (45%) had disease response, 6 (5 AML, 1 ALL) with complete remission (CR) and 3 (2 AML and 1 ALL) with no evidence of disease but failure to recover normal neutrophil and/or platelet counts or to remain in remission for at least 30 days (incomplete remission). Bcl-2 mRNA levels were down-regulated in 9 of the 12 (75%) evaluable patients. This study demonstrates that G3139 can be administered safely with FLAG chemotherapy and down-regulate its target, Bcl-2. The encouraging clinical and laboratory results justify the current plans for a phase 3 study in previously untreated high-risk AML (ie, age at least 60 years).
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PMID:Phase 1 and pharmacodynamic studies of G3139, a Bcl-2 antisense oligonucleotide, in combination with chemotherapy in refractory or relapsed acute leukemia. 1239 93

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