Therapeutic Potential of a Desert Plant Triterpenoid Molecule for Polycythemia Vera.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3635-3635 ◽  
Author(s):  
Amos S. Gaikwad ◽  
Jordan U. Gutterman ◽  
Josef T. Prchal
Keyword(s):  
Clinical Trials ◽  
Growth Inhibition ◽  
Polycythemia Vera ◽  
Progenitor Cells ◽  
Therapeutic Efficacy ◽  
Jak2 V617f ◽  
Malignant Cells ◽  
Erythroid Progenitor ◽  
Erythroid Progenitor Cells

Polycythemia vera (PV) is an acquired, clonal stem cell, myeloproliferative, hematological disorder with variable increase in erythrocytes, neutrophils and granulocytes. PV causes significant morbidity and mortality from thrombotic and hemorrhagic complications and has a propensity for leukemic transformation. Phlebotomy, interferon a and myelosuppressive chemotherapy have been the cornerstones of treatment to date. With no specific drugs to treat PV effectively, the development of new therapeutic modalities is important. A somatic mutation in the JAK2 tyrosine kinase (V617F) causing constitutive activation of the JAK/STAT pathway was recently reported in over 80% of PV patients. Based on this observation, we explored the therapeutic efficacy of tyrosine kinase inhibitors (TKIs) such as imatinib (Gaikwad A et al, Blood106: 2601, 2005) and AMN107 for PV. These TKIs showed marginal efficacy in vitro. Research using natural sources has led to important pharmacological targets for cancer therapy. Several plant molecules have either been introduced to the US market or are in late-phase clinical trials. We focused on a natural product called “Avicin D,” which is a plant derived triterpene electrophilic molecule with cyto-protective and anti-inflammatory functions (Haridas V et al, J. Clin. Invest113: 65, 2004; Haridas V et al, PNAS, 98:11557, 2001). Avicin D is reported to initiate selective pro-apoptotic activity in malignant cells (Mujoo K, et al. Cancer Res.61: 5486, 2001) by direct perturbation of mitochondria (Haridas V, et al. PNAS, 98: 5821, 2001). It has also been shown to down-regulate a group of pro-survival, anti-apoptotic proteins that act downstream of cytochrome c release, including HSP70, HSP90 and XIAP (Gaikwad A, et al. Clin. Cancer Res. 11: 1953Gaikwad A, et al. Clin. Cancer Res. 11: 2005). In addition, Avicin D also blocks glycolysis, a key metabolic process that malignant cells exploit for their proliferation and survival (Warburg phenomenon). To examine Avicin D’s therapeutic efficacy for PV, we utilized mouse reporter cells expressing the JAK2 V617F protein. Avicin D inhibited the growth of these cells with an IC50 of 2μM. Interestingly, in cells carrying wild-type JAK2 there was no significant inhibitory effect. In addition, Avicin D showed marked growth inhibition of human erythroleukemic cells (HEL) that harbor the JAK2 V617F mutation at an IC50 of 2μM. We then examined Avicin D’s effect on in vitro expanded native human erythroid progenitor cells. Avicin D showed specific growth inhibition of erythroid progenitor cells from PV patients (IC50 ~3μM) with no significant effect on the normal progenitors. We conclude that Avicin D should be a promising candidate for clinical trials of PV and other disorders that are associated with JAK2 V617F somatic mutations.

Excessive Isolated Erythrocytosis Linked to Induction of SCL/Tal1 and Erythropoietin Receptor Expression.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1244-1244
Author(s):  
Heather M. Rogers ◽  
Josef T. Prchal ◽  
Babette B. Weksler ◽  
Xiaobing Yu ◽  
Constance Tom Noguchi
Keyword(s):  
Cell Proliferation ◽  
Polycythemia Vera ◽  
Progenitor Cells ◽  
Jak2 V617f ◽  
Erythropoietin Receptor ◽  
Jak2 V617f Mutation ◽  
Erythroid Progenitor ◽  
Cell Numbers ◽  
Erythroid Progenitor Cells ◽  
V617f Mutation

Abstract The JAK2 V617F mutation has been detected in more than 90% polycythemia vera patients and is associated with increased erythropoietin (EPO) sensitivity or EPO independence of erythroid progenitor cells during early erythropoiesis. To determine if other molecular lesions give rise to increased erythrocytosis and realizing that the JAK2 V617F mutation may not be the initiating event in polycythemia vera, we identified an individual with isolated, excessive erythrocytosis who showed erythroid precursor hypersensitivity to EPO; no mutations on sequencing genes for erythropoietin receptor (EPO-R), VHL, or HIF-1 IRE; normal serum EPO level; normal hemoglobin function and p50; normal cardiac, hepatic and pulmonary function; no JAK2 V617F mutation and no EPO independent BFU-E. While it was not certain that this individual’s erythrocytosis was lifelong, other relatives had increased hemoglobin levels. The cause of this individual’s increased erythropoiesis was investigated using EPO-stimulated cultures of hematopoietic progenitor cells isolated from peripheral blood. As with normal controls, cell numbers were not increased after 12 days of incubation with low levels of EPO (<0.1 U/ml). With 1U/ml of EPO, cell proliferation was similar to control early in erythropoiesis but increased markedly after 8 days so that by day 12 cell numbers were 3-fold greater than in control cultures with 95% benzidine positive cells compared with 76% for control and 82–87% for JAK2 V617F positive erythroid progenitor cells. Analyses of transcription factor expression revealed that induction of GATA-1 and down regulation of GATA-2 were similar to control. However, SCL/Tal1 and EKLF markedly increased beginning at day 8 to 10 and continued to rise during late erythropoiesis in contrast to control and JAK2 V617F positive cultures in which SCL/Tal1 and EKLF peaked at day 10 and decreased with late erythroid differentiation. Since increased beta-globin expression is concomitant with induction of EKLF, the rise in EKLF may account for the marked increase in benzidine positive cells from our subject. Moreover, expression of EPO-R followed the continuing rise in SCL/Tal1, increasing by 3.5 fold at day 12 compared with control cultures. This high EPO-R expression is consistent with the dramatic increase in cell proliferation during late erythropoiesis. Using forced expression of SCL/Tal1, reporter gene assay and gel mobility shift analysis in erythroid cells, we determined that SCL/Tal1 is able to bind to E-boxes located 3′ of the EPO-R proximal promoter and to activate transcription. Although EPO stimulation of erythroid progenitor cells activates EPO-R, we found that forced expression of EPO-R in primary erythroid progenitor cells in the presence of EPO increases expression of GATA-1 as well as SCL/Tal1 and EKLF, providing further evidence that specific increase in SCL/Tal1 but not GATA-1 must precede induction of EPO-R in this case of excessive erythrocytosis. These data demonstrate a link between high level induction of SCL/Tal1 expression and increased erythrocytosis and suggest a mechanism that contributes to increased erythropoietin sensitivity during late erythropoiesis.

Human thymic epithelial cells maintain long-term survival of clonogenic myeloid and erythroid progenitor cells in vitro

2000 ◽  
Vol 111 (1) ◽  
pp. 363-370 ◽  
Author(s):  
Katsuto Takenaka ◽  
Mine Harada ◽  
Tomoaki Fujisaki ◽  
Koji Nagafuji ◽  
Shinichi Mizuno ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Progenitor Cells ◽  
Thymic Epithelial Cells ◽  
Erythroid Progenitor ◽  
Term Survival ◽  
Long Term Survival ◽  
Erythroid Progenitor Cells

scholarly journals Fetal erythropoiesis in steel mutant mice. III. Defect in differentiation from BFU-E to CFU-E during early development

Blood ◽  
1978 ◽  
Vol 51 (3) ◽  
pp. 539-547 ◽  
Author(s):  
DH Chui ◽  
SK Liao ◽  
K Walker
Keyword(s):  
Progenitor Cells ◽  
Early Development ◽  
The Other ◽  
Mutant Mice ◽  
Erythroid Progenitor ◽  
Erythroid Progenitor Cells ◽  
Other Hand ◽  
Colony Forming Units ◽  
Fetal Erythropoiesis

Abstract Erythroid progenitor cells in +/+ and Sl/Sld fetal livers manifested as burst-forming units-erythroid (BFU-E) and colony-forming units- erythroid (CFU-E) were assayed in vitro during early development. The proportion of BFU-E was higher as mutant than in normal fetal livers. On the other hand, the proportion of CFU-E was less in the mutant than in the normal. These results suggest that the defect in Sl/Sld fetal hepatic erythropoiesis is expressed at the steps of differentiation that effect the transition from BFU-E to CFU-E.

scholarly journals Ligand-dependent repression of the erythroid transcription factor GATA-1 by the estrogen receptor.

1995 ◽  
Vol 15 (6) ◽  
pp. 3147-3153 ◽  
Author(s):  
G A Blobel ◽  
C A Sieff ◽  
S H Orkin
Keyword(s):  
Bone Marrow ◽  
Estrogen Receptor ◽  
Transcription Factor ◽  
Progenitor Cells ◽  
Erythroid Cell ◽  
High Dose ◽  
Dependent Manner ◽  
Erythroid Progenitor ◽  
Erythroid Progenitor Cells

High-dose estrogen administration induces anemia in mammals. In chickens, estrogens stimulate outgrowth of bone marrow-derived erythroid progenitor cells and delay their maturation. This delay is associated with down-regulation of many erythroid cell-specific genes, including alpha- and beta-globin, band 3, band 4.1, and the erythroid cell-specific histone H5. We show here that estrogens also reduce the number of erythroid progenitor cells in primary human bone marrow cultures. To address potential mechanisms by which estrogens suppress erythropoiesis, we have examined their effects on GATA-1, an erythroid transcription factor that participates in the regulation of the majority of erythroid cell-specific genes and is necessary for full maturation of erythrocytes. We demonstrate that the transcriptional activity of GATA-1 is strongly repressed by the estrogen receptor (ER) in a ligand-dependent manner and that this repression is reversible in the presence of 4-hydroxytamoxifen. ER-mediated repression of GATA-1 activity occurs on an artificial promoter containing a single GATA-binding site, as well as in the context of an intact promoter which is normally regulated by GATA-1. GATA-1 and ER bind to each other in vitro in the absence of DNA. In coimmunoprecipitation experiments using transfected COS cells, GATA-1 and ER associate in a ligand-dependent manner. Mapping experiments indicate that GATA-1 and the ER form at least two contacts, which involve the finger region and the N-terminal activation domain of GATA-1. We speculate that estrogens exert effects on erythropoiesis by modulating GATA-1 activity through protein-protein interaction with the ER. Interference with GATA-binding proteins may be one mechanism by which steroid hormones modulate cellular differentiation.

scholarly journals Identification of Increased Protein Tyrosine Phosphatase Activity in Polycythemia Vera Erythroid Progenitor Cells

Blood ◽  
1997 ◽  
Vol 90 (2) ◽  
pp. 651-657 ◽  
Author(s):  
Xingwei Sui ◽  
Sanford B. Krantz ◽  
Zhizhuang Zhao
Keyword(s):  
Polycythemia Vera ◽  
Progenitor Cells ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Gel Filtration ◽  
Erythroid Progenitors ◽  
Erythroid Progenitor ◽  
Normal Cells ◽  
Protein Tyrosine ◽  
Erythroid Progenitor Cells

Abstract Polycythemia vera (PV) is a clonal hematologic disease characterized by hyperplasia of the three major bone marrow lineages. PV erythroid progenitor cells display hypersensitivity to several growth factors, which might be caused by an abnormality of tyrosine phosphorylation. In the present study, we have investigated protein tyrosine phosphatase (PTP) activity in highly purified erythroid progenitor cells and found that the total PTP activity in the PV cells was twofold to threefold higher than that in normal cells. Protein separation on anion-exchange and gel-filtration columns showed that the increased activity was due to a major PTP eluted at approximately 170 kD. This enzyme was sensitive to PTP inhibitors and it did not cross-react with antibodies to SHP-1, SHP-2, or CD45. Subcellular fractionation showed that the PTP localized with the membrane fraction, where its activity was increased by threefold in PV erythroid progenitors when compared with normal cells. As the erythroid progenitors progressively matured, activity of the PTP declined rapidly in the normal cells but at a much slower rate in the PV cells. These studies suggest that a potentially novel membrane or membrane-associated PTP, representing a major PTP activity, may have an important role in proliferation and/or survival of human erythroid progenitors and that its hyperactivation in PV erythroid progenitors might be responsible for the increased erythropoiesis in PV patients.

scholarly journals Pregnancy-Secreted Acid Phosphatase, Uteroferrin, Enhances Fetal Erythropoiesis

Endocrinology ◽  
2014 ◽  
Vol 155 (11) ◽  
pp. 4521-4530 ◽  
Author(s):  
Wei Ying ◽  
Haiqing Wang ◽  
Fuller W. Bazer ◽  
Beiyan Zhou
Keyword(s):  
Acid Phosphatase ◽  
Progenitor Cells ◽  
Fetal Liver ◽  
Hematopoietic Cells ◽  
Erythroid Progenitor ◽  
Colony Forming Unit ◽  
Erythroid Progenitor Cells ◽  
Uterine Glands ◽  
Fetal Erythropoiesis

Abstract Uteroferrin (UF) is a progesterone-induced acid phosphatase produced by uterine glandular epithelia in mammals during pregnancy and targeted to sites of hematopoiesis throughout pregnancy. The expression pattern of UF is coordinated with early fetal hematopoietic development in the yolk sac and then liver, spleen, and bone to prevent anemia in fetuses. Our previous studies suggested that UF exerts stimulatory impacts on hematopoietic progenitor cells. However, the precise role and thereby the mechanism of action of UF on hematopoiesis have not been investigated previously. Here, we report that UF is a potent regulator that can greatly enhance fetal erythropoiesis. Using primary fetal liver hematopoietic cells, we observed a synergistic stimulatory effect of UF with erythropoietin and other growth factors on both burst-forming unit-erythroid and colony-forming unit-erythroid formation. Further, we demonstrated that UF enhanced erythropoiesis at terminal stages using an in vitro culture system. Surveying genes that are crucial for erythrocyte formation at various stages revealed that UF, along with erythropoietin, up-regulated transcription factors required for terminal erythrocyte differentiation and genes required for synthesis of hemoglobin. Collectively, our results demonstrate that UF is a cytokine secreted by uterine glands in response to progesterone that promotes fetal erythropoiesis at various stages of pregnancy, including burst-forming unit-erythroid and colony-forming unit-erythroid progenitor cells and terminal stages of differentiation of hematopoietic cells in the erythroid lineage.

UCP2 Modulates Cell Proliferation through the MAPK/ERK Pathway during Erythropoiesis and Has No Effect on Heme Biosynthesis

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5372-5372
Author(s):  
Alvaro A Elorza ◽  
Brigham B Hyde ◽  
Hanna Mikkola ◽  
Sheila Collins ◽  
Orian S Shirihai
Keyword(s):  
Cell Proliferation ◽  
Progenitor Cells ◽  
Fetal Liver ◽  
Mitochondrial Protein ◽  
Erythroid Progenitor ◽  
Heme Synthesis ◽  
Erythroid Progenitor Cells ◽  
Deficient Mice

Abstract UCP2, an inner membrane mitochondrial protein, has been implicated in bioenergetics and Reactive Oxygen Species (ROS) modulation. UCP2 has been previously hypothesized to function as a facilitator of heme synthesis and iron metabolism by reducing ROS production. While UCP2 has been found to be induced by GATA1 during erythroid differentiation its role in erythropoiesis in vivo or in vitro has not been reported thus far. Here we report on the study of UCP2 role in erythropoiesis and the hematologic phenotype of UCP2 deficient mouse. In vivo we found that UCP2 protein peaks at early stages of erythroid maturation when cells are not fully committed in heme synthesis and then becomes undetectable at the reticulocyte stage. Iron incorporation into heme was unaltered in erythroid cells from UCP2 deficient mice. While heme synthesis was not influenced by UCP2 deficiency, mice lacking UCP2 had a delayed recovery from chemically induced hemolytic anemia. Analysis of the erythroid lineage from bone marrow and fetal liver revealed that in the UCP2 deficient mice the R3 (CD71high/Ter119high) population was reduced by 24%. The count of BFU-E and CFU-E colonies, scored in an erythroid colony assay, was unaffected, indicating an equivalent number of early erythroid progenitor cells in both UCP2 deficient and control cells. Ex-vivo differentiation assay revealed that UCP2 deficient c-kit+ progenitor cells expansion was overall reduced by 14% with population analysis determining that the main effect is at the R3 stage. No increased rate of apoptosis was found indicating that expansion rather than cell death is being compromised. Reduced expansion of c-kit+ cells was accompanied by 30% reduction in the phosphorylated form of ERK, a ROS dependent cytosolic regulator of cell proliferation. Analysis of ROS in UCP2 null erythroid progenitors revealed altered distribution of ROS resulting in 14% decrease in cytosolic and 32% increase in mitochondrial ROS. Restoration of the cytosolic oxidative state of erythroid progenitor cells by the pro-oxidant Paraquat reversed the effect of UCP2 deficiency on cell proliferation in in vitro differentiation assays. Together, these results indicate that UCP2 is a regulator of erythropoiesis and suggests that inhibition of UCP2 function may contribute to the development of anemia.

In vitro induction of fetal hemoglobin in human erythroid progenitor cells

2003 ◽  
Vol 31 (7) ◽  
pp. 586-591 ◽  
Author(s):  
Janie A. Ho ◽  
Chrisley V. Pickens ◽  
Michael P. Gamscik ◽  
O.Michael Colvin ◽  
Russell E. Ware
Keyword(s):  
Progenitor Cells ◽  
Fetal Hemoglobin ◽  
Erythroid Progenitor ◽  
Erythroid Progenitor Cells ◽  
In Vitro Induction

scholarly journals Prostaglandin-mediated suppression of in vitro growth of erythroid progenitor cells

1989 ◽  
Vol 36 (4) ◽  
pp. 712-718 ◽  
Author(s):  
Shuichi Taniguchi ◽  
Tsunefumi Shibuya ◽  
Mine Harada ◽  
Yoshiyuki Niho
Keyword(s):  
Progenitor Cells ◽  
In Vitro Growth ◽  
Erythroid Progenitor ◽  
Erythroid Progenitor Cells

scholarly journals Abnormal erythroid progenitor cells in human preleukemia

Blood ◽  
1982 ◽  
Vol 60 (2) ◽  
pp. 362-367 ◽  
Author(s):  
DH Chui ◽  
BJ Clarke
Keyword(s):  
Progenitor Cells ◽  
Peripheral Blood ◽  
Culture Technique ◽  
The Other ◽  
Erythroid Cell ◽  
Erythroid Progenitor ◽  
Clonal Culture ◽  
Erythroid Progenitor Cells ◽  
Marrow Cells

Abstract Ten patients with preleukemia were studied by the erythroid cell clonal culture technique. In nine of these patients, erythroid colonies derived from peripheral blood BFU-E were not observed, while the other patient had markedly decreased peripheral blood BFU-E-derived erythroid colonies in vitro. In three patients, marrow cells were also cultured and no BFU-E-derived erythroid colonies were detected. These studies indicate that immature erythroid progenitor cells, BFU-E, in patients with preleukemia are either markedly decreased in number or grossly defective in their proliferative or differentiative capacities.

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