Interferon-Alpha Preferentially Targets JAK2V617F-Positive Rather Than Wild-Type Early Progenitor Cells in Myeloproliferative Disorders.

Abstract Abstract 436 Polycythemia vera (PV), essential thrombocytemia (ET) and primary myelofibrosis (PMF) are myeloproliferative disorders (MPDs) without curative treatment, unless hematopoietic stem cell (HSC) transplantation is performed. However, for several years the use of interferon-alpha (IFNα) has provided an efficient therapeutic alternative for MPD patients. IFNα was shown to induce complete long-term hematologic and molecular remissions in JAK2V617F-positive MPD patients, suggesting a possible curative effect of IFNα. In order to better understand mechanisms of action of this drug, experiments were perfomred on cell lines, patient cells and mice cells harboring a JAK2V617F mutation. We hypothesized that IFNα may target directly MPD cells through binding to its specific receptor, in addition to the potential immunological effect of this molecule and could induce cell cycle entry of the pathological quiescent HSCs. Human cell lines harboring JAK2 mutation or BCR-ABL oncogene were treated with increasing doses of IFNα. A significant anti-proliferative effect at low concentrations (100 IU/ml) on the JAK2V617F-positive HEL cell line was observed. On the contrary, at this low dose IFNα did not influence growth of the BCR-ABL-positive K562 and the non-mutated UT-7 cell lines. This result supported a direct effect of IFNα in JAK2V617F cells. Suppressor of cytokine signaling (SOCS) are potent inhibitors of the JAK-STAT pathway by proceeding to a classic negative regulation loop proteins. Following IFNα stimulation of HEL cells, SOCS1 and SOCS3 mRNAs expression were induced (p=0.00036 and p=0.0012, respectively) and efficient knock-down of either SOCS1 or SOCS3 by shRNAs expression in HEL cells was able to counteract the anti-proliferative effect of IFNα (p=0.028 and p=0.031, respectively). We concluded that SOCS1 and SOCS3 are involved, in IFNα proliferative inhibition activity of HEL cells. To determine whether JAK2V617F confer hypersensitivity to IFNα inhibitory effect, proliferation and genotyping of CD34+ progenitors isolated from the bone marrow of JAK2V617F–positive MPD patients (n=5) and control subjects (n=4) were plated at one cell per well in 96-well plates and counted and genotyped at Day 10-12. A significant decrease of the patients progenitors clonogenicity was observed when exposed to IFNα (10 000 IU/ml, p<0.05). On the contrary, normal progenitors were not sensitive to the anti-proliferative effect of IFNα (p=0.2). Patients colonies were genotyped for JAK2V617F. After IFNα exposure, the amount of homozygous JAK2V617F clones decreased in 3 over 5 patients in favor of the heterozygous JAK2V617F and/or wild-type clone(s) confirming the preferential action of IFNα on JAK2V617F progenitors. This inhibitory effect was more drastic on progenitors carrying the JAK2V617F mutation at the homozygous state. Lastly, in order to explain the long term molecular responses observed in PV patients treated by IFNα, we investigated the effect of IFNα on the cell cycle in more immature cells. BrdU assay on JAK2V617F Knock-in (KI) mice was performed. Five-months old JAK2V617F KI and wild-type mice received or not 10,000 UI of murine IFNα during 3 days. Sixteen hours before analysis, BrdU was injected i.p. in the animals. Bone marrow Lin-Sca+cKit+cells (LSK) were stained with CD150 and CD48 antibodies before BrdU labelling was analyzed by flow cytometry. Analysis of BrdU postive cells confirmed that i-JAK2V617F induces LSK CD150+CD48- to enter cell cycle ( 8.55+/-3.12% for WT cells versus 19.92+/-3,19% for JAK2V617F KI cells respectively (p = 0.04)) and ii- That IFNα induces CD150+CD48- LSK to enter cell cycle whatever the JAK2 WT (8.55+/-3.12% for non treated animals versus 15.43+/-3.19% for IFNα receiving mice (p=0.02)) or mutated status but this induction was more statistically significant in JAK2V617F mice (19.92+/-1.82% versus 25.23+/-0.57% respectively( p=0.02)). In conclusion, we gave rise to a double effect of IFNα in MPD cells: A direct preferential anti-proliferative effect of IFNα on JAK2V617F–positive MPD progenitor cells, possibly through the induction of SOCS over-expressions and a direct cell cycling effect on JAK2V617F stem cells suggesting that IFNa containing treatments could be of interest for JAK2V617F patients cure. Disclosures: No relevant conflicts of interest to declare.

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Over-expression of c-src or v-src in bone marrow stromal cells stimulates hematopoiesis in long-term bone marrow culture

Blood ◽

10.1182/blood.v80.12.3079.bloodjournal80123079 ◽

1992 ◽

Vol 80 (12) ◽

pp. 3079-3089

Author(s):

J Mladenovic ◽

SM Anderson

Keyword(s):

Bone Marrow ◽

Cell Line ◽

Progenitor Cells ◽

Cell Lines ◽

Stromal Cells ◽

Stromal Cell ◽

Conditioned Media ◽

Enzyme Linked Immunosorbent Assay ◽

Gm Csf

The S17 murine stromal cell line was infected with retroviral vectors encoding the v-src and c-src oncogenes and cells expressing high levels of either pp60v-src or pp60c-src were isolated. Long-term bone marrow cultures (LTBMCs) established with these different stromal cell lines showed that progenitor cells proliferated to a greater extent in cultures with stromal cells that over-expressed either c-src or v-src. An increase in the number of granulocytes, monocytes, and colony- forming units granulocyte-macrophage (CFU-GM) in the nonadherent cell population of LTBMCs prepared with S17/v-src or S17/c-src stromal cells was observed. Conditioned media from the S17/v-src and S17/src stromal cell lines stimulated the formation of CFU-GM in the absence of additional hematopoietic cell growth factors. Conditioned media from S17/v-src and S17/c-src stimulated proliferation of the granulocyte- macrophage colony-stimulating factor (GM-CSF)-responsive cell line FDCP-1 and this stimulation was inhibited by neutralizing antisera to murine GM-CSF. An increase in the concentration of GM-CSF was confirmed by enzyme-linked immunosorbent assay. No secretion of interleukin-1 alpha (IL-1 alpha) or tumor necrosis factor-alpha was detected by any of the stromal cell lines. There was no increase in the secretion of either CSF-1 or IL-6 by either S17/v-src or S17/c-src. The addition of 1 micrograms/mL monoclonal anti-GM-CSF antibody to LTBMCs caused a decrease in the number of nonadherent cells in cultures established with each of the different stromal cell lines. Northern blot analysis showed no difference in the level of GM-CSF RNA among the different stromal cell lines. These studies suggest that the increased proliferation of hematopoietic progenitor cells in LTBMCs with S17/v-src or S17/c-src cells may result from a posttranscriptional event that elevates production of GM-CSF by the S17/c-src and S17/v-src stromal cells.

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Hypoxia-reoxygenation induces premature senescence in FA bone marrow hematopoietic cells

Blood ◽

10.1182/blood-2004-08-3033 ◽

2005 ◽

Vol 106 (1) ◽

pp. 75-85 ◽

Cited By ~ 42

Author(s):

Xiaoling Zhang ◽

June Li ◽

Daniel P. Sejas ◽

Qishen Pang

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Bone Marrow ◽

Hematopoietic Cells ◽

Premature Senescence ◽

Wild Type ◽

Cell Cycle Profile ◽

Cycle Arrest ◽

Associated Proteins

Hematopoietic cells are often exposed to transient hypoxia and reoxygenation as they develop and migrate. Given that bone marrow (BM) failure occurred in patients with Fanconi anemia (FA), we reason that hypoxia-then-reoxygenation represents a physiologically relevant stress for FA hematopoietic progenitor/stem cells. Here we show that expansion of Fancc–/– BM cells enriched for progenitor and stem cells was significantly decreased after 2 continuous cycles of hyperoxic-hypoxic-hyperoxic treatments compared with wild-type (WT) BM cells. This inhibition was attributable to a marked decrease of lineage-depleted (Lin–) ScaI– c-kit+ cells and more primitive Lin– ScaI+ c-kit+ cells in Fancc–/– BM cells following reoxygenation. Evaluation of the cell-cycle profile of long-term BM culture (LTBMC) revealed that a vast majority (70.6%) of reoxygenated Fancc–/– LTBMC cells was residing in the G0 and G1 phases compared with 55.8% in WT LTBMC cells. Fancc–/– LTBMC cells stained intensely for SA-β-galactosidase activity, a biomarker for senescence; this was associated with increased expression of senescence-associated proteins p53 and p21WAF1/CIP1. Taken together, these results suggest that reoxygenation induces premature senescence in Fancc–/– BM hematopoietic cells by signaling through p53, up-regulating p21, and causing senescent cell-cycle arrest. Thus, reoxygenation-induced premature senescence may be a novel mechanism underlying hematopoietic cell depletion and BM failure in FA.

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Induction of CABLES1 by the TKI Inhibits the Cell Cycle Progression and Induces Apoptosis In CML Cell.

Blood ◽

10.1182/blood.v116.21.1199.1199 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1199-1199

Author(s):

Tomonari Takemura ◽

Satoki Nakamura ◽

Yasuyuki Nagata ◽

Daisuke Yokota ◽

Isao Hirano ◽

...

Keyword(s):

Cell Cycle ◽

Bone Marrow ◽

Cell Proliferation ◽

Progenitor Cells ◽

Cell Lines ◽

Cell Cycle Progression ◽

Kinase Inhibitors ◽

Cycle Progression ◽

Abl Kinase ◽

Abl Kinase Inhibitors

Abstract Abstract 1199 [Background and Aims] CABLES1 (cyclin-dependent kinase (CDK)-5 and ABL enzyme 1) is a regulator of cell proliferation, apoptosis, and cell cycle, and it has been reported to be lost in a variety cancers. It has been also reported that knockout of the Cable1 gene has minimal to no effect on hematopoietic stem cells. However, we found that the expression of Cables1 gene and CABLES1 protein was suppressed in CML cells, and its function is little known in CML. In this study, we have investigated the function of CABLES1 in CML cell proliferation. [Methods] The cells used in this study were human CML cell lines, K562, Meg01 and SHG3 cells. Primary CML cells (ALDHhi cells) were obtained from the bone marrow of CML (CP) patients (n=12). Human normal ALDHhi cells were isolated from bone marrow of healthy volunteers after obtaining informed consents. For analysis of Cables1 mRNA expression, quantitative RT-PCR was performed in all cell lines treated with Abl kinase inhibitors (STI571, AMN107, and BMS354825). For cell survival analysis and the levels of p53 and some CDKIs in CML cells, MTT assays, western blot and cell cycle analysis were performed in all cell lines transfected with Cables1 shRNA or cDNA. For colony analysis, the colonies of CFU-GEMM, CFU-GM, and BFU-E were counted in CML stem/progenitor cells transfected with Cables1 cDNA or shiRNA, or treated with Abl kinase inhibitors. [Results] In CML cell lines, the expressions of Cables1 mRNA and CABLES1 protein were significantly increased by treatment with Abl kinase inhibitors or transfection with Bcr-Abl shRNA. In CML cells transfected with the Cables1 cDNA, it is shown that CML cell proliferation was inhibited, and the phosphorylation levels of p53, and the expression of BAX and p21 protein were markedly increased compared to the untransfected cells. In addition, the overexpression of CABLES1 induced G1 cell cycle arrest and reduced the DiOC6 fluorescence, indicating breakdown of the mitochondrial membrane potential in CML cells. On the other hand, the changes of p73 and p27 protein expression were not detected. Moreover, in CML cells transfected with Cables1 shRNA, the inhibition of CML cell proliferation by the Abl kinase inhibitors were weakened. In CML stem/progenitor cells (ALDHhi cells) obtained from patients with CML, the expression of Cables1 mRNA was suppressed, and the transfection with Bcr-Abl shRNA or treatment with Abl kinase inhibitors increased the expression of Cables1 mRNA and CABLES1 protein, and decreased the counts of CFU-GEMM, CFU-GM and BFU-E. [Conclusion] Our results demonstrated that the Bcr-Abl suppressed the expression of CABLES1, and the depletion of CABLES1 promotes cell cycle progression and p53-dependent apoptosis. Moreover, the induction of CABLES1 expression has the potentiality to eradicate CML stem/progenitor cells. Disclosures: No relevant conflicts of interest to declare.

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HDAC8 Regulates Long-Term Hematopoietic Stem Cell Quiescence and Maintenance

Blood ◽

10.1182/blood.v128.22.1468.1468 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1468-1468

Author(s):

Wei-Kai Hua ◽

Jing Qi ◽

Qi Cai ◽

Emily Carnahan ◽

Ling Li ◽

...

Keyword(s):

Cell Cycle ◽

Bone Marrow ◽

Poly I:C ◽

Control Group ◽

Wild Type ◽

Hematopoietic Stem ◽

Cell Fate Decisions ◽

Polycytidylic Acid ◽

Deficient Mice

Abstract Long-term (LT) hematopoietic stem cells (HSC) are responsible for life-long production of mature blood cells of all lineages through tightly concerted cell fate decisions including quiescence, self-renewal, differentiation and apoptosis. Histone deacetylase 8 (HDAC8) is a member of class I HDAC enzymes that remove acetyl moieties from lysine residues on histones and a variety of non-histone proteins. Specifically, HDAC8 has been shown to modulate the acetylation cycle of cohesin complex protein SMC3. Loss-of-function mutations in HDAC8, located on the X chromosome q13, have been found in patients with Cornelia de Lange Syndrome (CdLS) and those with CdLS-like features. These HDAC8 mutations are associated with severely skewed X-inactivation (100% wild type allele) in the peripheral blood of female patients, possibly due to selection against the mutant alleles. However, the expression and function of HDAC8 in normal HSCs and hematopoiesis remain unknown. In this study, we show that Hdac8 is highly expressed in the phenotypic LT-HSC (Lin-cKit+Sca1+CD150+CD48-) population in adult mice. To determine the function of HDAC8 in adult hematopoiesis, we generated conditional Hdac8 deficient mice using the Mx1-Cre and a floxed Hdac8 allele (Mx1-Cre/Hdac8f/f(y)) andconfirmed that Hdac8 is successfully deleted by polyinosinic-polycytidylic acid [poly (I:C)] treatment. Phenotypic analysis of Hdac8 deficient mice showed increased LT-HSC population compared to similarly treated control mice. However, largely normal steady state hematopoietic profile was found in Hdac8 deficient mice at 6 weeks and 1 year after induction. To further track Hdac8-deleted cells, we generated Cre/Hdac8f/f(y) mice with a dual fluorescence Rosa26mT/mG (mT/mG) Cre reporter allele, which expresses dTomato prior to Cre induction and becomes GFP+ after Cre-mediated recombination. We assessed hematopoietic repopulation by transplanting bone marrow cells from Cre/Hdac8f/f(y)/mTmG+mice (2 x 105) together with wild type support cells (2 x 105) into lethally irradiated CD45.1+ congenic recipients. Hdac8 deletion was induced by treating the recipients with 7 does (14 m▢g/kg/dose) of poly (I:C). We found that Hdac8 deletion did not affect CD45.2+ or GFP+ donor-derived overall engraftment or lineage repopulation up to 16 weeks. There was also no change in the frequency or number of GFP+ donor-derived phenotypic LT-HSCs in the bone marrow. Serial transplantation was performed to further assess long-term repopulating activity of HSCs. Hdac8 deficient cells were significantly (p=0.019; n=3) compromised in multi-lineage repopulation in secondary transplant recipients. Except a modest reduction in Pre-GM, there was no change in the overall composition of Hdac8 deficient CD45.2+-derived populations. Upon tertiary transplantation, no donor engraftment was observed for Hdac8 deficient cells (0 out of 4) compared to 50% positive engraftment in control group (4 out of 8). These results indicate that HDAC8 is crucial for maintaining long-term serial-repopulating activity over time. Cell cycle analysis revealed that Hdac8 deficient LT-HSCs display reduced quiescence and increased cycling, consistent with the increased number of phenotypic LT-HSC seen in Hdac8 deleted mice. Therefore, we further tested the sensitivity of Hdac8 deficient mice to serial ablation with 5-fluorouracil (5FU), an S phase-specific cytotoxic chemotherapeutic agent. Impaired hematopoietic recovery and increased lethality (p<0.001; n=23) was seen in Hdac8 deficient mice treated with 5-FU (100 mg/kg) every 7 days, indicating that Hdac8 deletion renders hypersensitivity to serial ablation. There were significnatly less phenotypic LT-HSCs in Hdac8 deficient mice 6 days after 5-FU treatment (p<0.01; n=4). In parallel, we observed increased DNA strand beaks as indicated by γ-H2AX staining and comet assays (p<0.001; n>100 cells). Analysis of p53 activation, cell cycle regulators and DNA dmage response are ongoing. Collectively, our study indicates that HDAC8 plays a pivotal role in LT-HSC quiescence and maintenance. Disclosures No relevant conflicts of interest to declare.

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Absence of nNOS Increases Longevity of Long Term Bone Marrow Cultures and Radiation Resistance.

Blood ◽

10.1182/blood.v106.11.4197.4197 ◽

2005 ◽

Vol 106 (11) ◽

pp. 4197-4197

Author(s):

Shaonan Cao ◽

Emily E. Greenberger ◽

Michael W. Epperly ◽

Anthony J. Kanai ◽

Joel S. Greenberger

Keyword(s):

Nitric Oxide ◽

Cell Cycle ◽

Bone Marrow ◽

Cell Lines ◽

Knockout Mice ◽

Radiation Resistance ◽

Irradiation Damage ◽

Bone Marrow Cultures ◽

Marrow Cultures

Abstract Neuronal nitric oxide synthase (nNOS) has been shown to be localized to the mitochondrial membrane. The mitochondria play an important role in irradiation-induced apoptosis. Following irradiation, there is increased production of superoxide as well as an induction of nitric oxide in mitochondria. The combination of superoxide and nitric oxide results in production of peroxynitrite, a very strong oxidant that produces lipid peroxidation. Previous data have demonstrated that lack of nNOS protects the bladder from ionizing irradiation damage. To determine the role of nNOS in hematopoiesis, we established long term bone marrow cultures (LTBMCs) from nNOS deletion recombinant negative (knockout) mice as well as nNOS+/+ littermate mice. LTBMCs from nNOS knockout mice compared to +/+ control demonstrated increased total cumulative cell production (32.2 x 106 and 15.9 x 106 non-adherent cells, respectively), cobblestone island formation (5073 and 1106, respectively), and increased cumulative generation of day 14 CFU-GEMM colony forming cells per 105 plated (325 ± 30.4 and 9 ± 2.5 colonies, respectively) over 20 weeks in culture. IL-3 dependent non-adherent cell lines derived from the nNOS-/- and the nNOS+/+ cultures were tested for radiosensitivity. Cells from the nNOS−/− cell line demonstrated decreased radiation apoptosis 24 hours following irradiation, 5.89 ± 0.71% apoptotic cells compared to 10.42 ± 1.19% for the control littermates (p=0.041). Cell cycle analysis of littermate cells at 24 hours after 10 Gy demonstrated a G0/G1 and a G2/M block while there was no change in the cell cycle distribution of the nNOS−/− cells. The data demonstrate that absence of nNOS increases the longevity of hematopoiesis in LTBMCs and increases the radiation resistance of hematopoietic cell lines derived from such cultures.

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Downregulation of THAP11 by Bcr-Abl Promotes c-Myc-Mediated CML Cell Proliferation.

Blood ◽

10.1182/blood.v114.22.3255.3255 ◽

2009 ◽

Vol 114 (22) ◽

pp. 3255-3255

Author(s):

Daisuke Yokota ◽

Satoki Nakamura ◽

Tomonari Takemura ◽

Isao Hirano ◽

Shinya Fujisawa ◽

...

Keyword(s):

Cell Cycle ◽

Bone Marrow ◽

Cell Proliferation ◽

Progenitor Cells ◽

Cell Lines ◽

Kinase Inhibitors ◽

Mononuclear Cells ◽

Conflicts Of Interest ◽

Abl Kinase ◽

Abl Kinase Inhibitors

Abstract Abstract 3255 Poster Board III-1 [Background and Purpose] THAP11 (thanatos-associated protein 11) is one of the zinc-dependent, sequence-specific DNA-binding factors, which regulate cell proliferation, apoptosis and cell cycle. It has been reported that THAP11 is ubiquitously expressed in normal tissues and frequently downregulated in several tumors. In CML cells, we found that THAP11 expression was inhibited. We investigated the mechanisms of the suppression of THAP11 and its function in CML cell proliferation. [Methods] The cells used in this study were human CML cell lines, K562 and Meg01 cells. Primary CML cells were obtained from the bone marrow of CML (CP) patients. Human normal mononuclear cells (MNCs) were isolated from bone marrow of healthy volunteers after obtaining informed consents. For analysis of THAP11 mRNA expression, quantitative RT-PCR was performed in all cell lines treated with Abl kinase inhibitors (STI571, AMN107, and BMS354825). For proliferation analysis and the expression of c-Myc in CML cells, MTT assays, western blot and cell cycle analysis were performed in all cell lines transfected with Bcr-Abl siRNA, THAP11 siRNA, or THAP11 cDNA respectively. Moreover, THAP11 expression, c-Myc expression, and the colony counts of CFU-GEMM, CFU-GM, and BFU-E were analyzed in CML stem/progenitor cells transfected with Bcr-Abl siRNA or treated with Abl kinase inhibitors. [Results] In CML cell lines treated with Abl kinase inhibitors or transfected with Bcr-Abl siRNA, the expressions of THAP11 and c-Myc mRNA and protein were significantly increased compared to untreated cells. On the other hand, in CML cells transfected with the THAP11 cDNA, the c-Myc expression was suppressed. The overexpression of THAP11 induced G1 cell cycle arrest through p27 and p21 accumulation, and inhibited the CML cell proliferation. Moreover, in CML stem/progenitor cells obtained from patients with CML, the transfection with Bcr-Abl siRNA or treatment with Abl kinase inhibitors increased the expression of THAP11 mRNA and protein, and decreased the c-Myc expression and the counts of CFU-GEMM, CFU-GM and BFU-E. [Conclusion] Our results demonstrated that the Bcr-Abl suppressed the expression of THAP11, the depletion of THAP11 induced c-Myc expression, and induced the proliferation of CML cells through cell cycle progression. Moreover, induction of THAP11 expression inhibited the proliferation of CML stem/progenitor cells. Disclosures: No relevant conflicts of interest to declare.

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Activation of Raf-1 through the Depletion of RKIP by Bcr-Abl Promotes CML Cell Proliferation

Blood ◽

10.1182/blood.v116.21.5105.5105 ◽

2010 ◽

Vol 116 (21) ◽

pp. 5105-5105

Author(s):

Satoki Nakamura ◽

Tomonari Takemura ◽

Yasuyuki Nagata ◽

Daisuke Yokota ◽

Isao Hirano ◽

...

Keyword(s):

Cell Cycle ◽

Bone Marrow ◽

Cell Proliferation ◽

Progenitor Cells ◽

Cell Lines ◽

Kinase Inhibitors ◽

Conflicts Of Interest ◽

Abl Kinase ◽

Cell Proliferation Inhibition ◽

Abl Kinase Inhibitors

Abstract Abstract 5105 [Background and Aims] RKIP (Raf kinase inhibitor protein) regulates cell proliferation, apoptosis, and cell cycle through the inhibition of Raf-1, and it has been reported that the suppression of the RKIP expression promotes the proliferation of tumor cells. However, its function is little known in CML. We found that the expression of RKIP gene and protein was suppressed in CML cells. In this study, we have investigated the expression and the function of the RKIP in CML cell proliferation. [Methods] The cells used in this study were human CML cell lines, K562, Meg01, and SHG3 cells. Primary CML cells (ALDHhicells) were obtained from the bone marrow of CML (CP) patients (n=12). Human normal ALDHhi cells were isolated from bone marrow of healthy volunteers after obtaining informed consents. For analysis of RKIP mRNA expression, quantitative RT-PCR was performed in all cell lines treated with Abl kinase inhibitors (STI571, AMN107, and BMS354825). For proliferation analysis and the levels of Erk1/2 phosphorylation in CML cells, MTT assays, western blot and cell cycle analysis were performed in all cell lines transfected with Bcr-Abl, RKIP siRNA, or RKIP cDNA respectively. For colony analysis, the colonies of CFU-GEMM, CFU-GM, and BFU-E were counted in CML stem/progenitor cells transfected with RKIP siRNA or treated with Abl kinase inhibitors. [Results] In CML cell lines treated with Abl kinase inhibitors or transfection with Bcr-Abl siRNA, the expressions of RKIP mRNA and protein were significantly increased more than untreated cells. Moreover, in CML cells transfected with the RKIP siRNA, the cell proliferation inhibition by treatment of the Abl kinase inhibitors was weakened compared to RKIP siRNA-untransfected cells, and the phosphorylation levels of Erk1/2 and Raf-1 were markedly increased compared to theRKIP siRNA-untransfected cells. On the other hands, the overexpression of RKIP induced G1 cell cycle arrest through p27 and p21 accumulation, decreased the phosphorylation levels of ERK1/2 and Raf-1, and inhibited the proliferation in CML cells. In CML stem/progenitor cells obtained from patients with CML, the expression of RKIP mRNA was suppressed in 10/10 (100 %) of CML. The transfection with Bcr-Abl siRNA or treatment with Abl kinase inhibitors increased the expression of RKIP mRNA and protein, and the overexpression of RKIP decreased the counts of CFU-GEMM, CFU-GM and BFU-E. [Conclusion] Our results demonstrated that the Bcr-Abl suppressed the expression of RKIP, the depletion of RKIP induced Raf-1 activation, and induced the proliferation of CML cells through ERK1/2 phosphorylation. Moreover, in CML, the induction of RKIP expression inhibited the proliferation of CML stem/progenitor cells. Disclosures: No relevant conflicts of interest to declare.

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Over-expression of c-src or v-src in bone marrow stromal cells stimulates hematopoiesis in long-term bone marrow culture

Blood ◽

10.1182/blood.v80.12.3079.3079 ◽

1992 ◽

Vol 80 (12) ◽

pp. 3079-3089 ◽

Cited By ~ 2

Author(s):

J Mladenovic ◽

SM Anderson

Keyword(s):

Bone Marrow ◽

Cell Line ◽

Progenitor Cells ◽

Cell Lines ◽

Stromal Cells ◽

Stromal Cell ◽

Conditioned Media ◽

Enzyme Linked Immunosorbent Assay ◽

Gm Csf

Abstract The S17 murine stromal cell line was infected with retroviral vectors encoding the v-src and c-src oncogenes and cells expressing high levels of either pp60v-src or pp60c-src were isolated. Long-term bone marrow cultures (LTBMCs) established with these different stromal cell lines showed that progenitor cells proliferated to a greater extent in cultures with stromal cells that over-expressed either c-src or v-src. An increase in the number of granulocytes, monocytes, and colony- forming units granulocyte-macrophage (CFU-GM) in the nonadherent cell population of LTBMCs prepared with S17/v-src or S17/c-src stromal cells was observed. Conditioned media from the S17/v-src and S17/src stromal cell lines stimulated the formation of CFU-GM in the absence of additional hematopoietic cell growth factors. Conditioned media from S17/v-src and S17/c-src stimulated proliferation of the granulocyte- macrophage colony-stimulating factor (GM-CSF)-responsive cell line FDCP-1 and this stimulation was inhibited by neutralizing antisera to murine GM-CSF. An increase in the concentration of GM-CSF was confirmed by enzyme-linked immunosorbent assay. No secretion of interleukin-1 alpha (IL-1 alpha) or tumor necrosis factor-alpha was detected by any of the stromal cell lines. There was no increase in the secretion of either CSF-1 or IL-6 by either S17/v-src or S17/c-src. The addition of 1 micrograms/mL monoclonal anti-GM-CSF antibody to LTBMCs caused a decrease in the number of nonadherent cells in cultures established with each of the different stromal cell lines. Northern blot analysis showed no difference in the level of GM-CSF RNA among the different stromal cell lines. These studies suggest that the increased proliferation of hematopoietic progenitor cells in LTBMCs with S17/v-src or S17/c-src cells may result from a posttranscriptional event that elevates production of GM-CSF by the S17/c-src and S17/v-src stromal cells.

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The Cell Cycle in Hematopoietic Stem Cells, Lin−/C-kit+/Sca1+ Fraction, Is Regulated by Connexin 32, Specifically Expressed in the Stem Cell Compartment

Blood ◽

10.1182/blood.v112.11.4775.4775 ◽

2008 ◽

Vol 112 (11) ◽

pp. 4775-4775

Author(s):

Yoko Hirabayashi ◽

Byung-Il Yoon ◽

Isao Tsuboi ◽

Yan Huo ◽

Yukio Kodama ◽

...

Keyword(s):

Cell Cycle ◽

Bone Marrow ◽

Progenitor Cells ◽

Progenitor Cell ◽

Bone Marrow Cells ◽

Wild Type ◽

Cell Compartment ◽

Hematopoietic Stem ◽

In The Wild ◽

Marrow Cells

Abstract Connexin (Cx) functions in the organization of cell-cell communication via gap junctions in multicellular organisms. Gap junctions have been implicated in the homeostatic regulation of various cellular functions, including growth control, cellular differentiation, apoptosis and the synchronization of electrotonic and metabolic functions. As Cxs are essential molecules for multicellular organisms, Cxs that organize cell-cell communication within the hematopoietic progenitor cell compartment are surmised to be present in bone marrow tissue. Recently, we first found that Cx32 is only Cx molecule expressed in the bone marrow in wild-type mice by means of comparison with Cx32-knockout (KO) mice, studied by a reverse biological approach. Cx32 is specifically expressed in primitive hematopoietic stem/progenitor cells, i.e., the lineage marker-negative (Lin−)/c-kit positive (c-kit+)/stem cell antigen-1-positive (Sca1+) (=LKS) fraction, and likely playing a role of restoration of stem/progenitor cell-quiescence, thereby preventing primitive stem cells from exhaustion. In this study, we present results on cell cycle analyses with respect to the function of Cx32; one for colony-forming progenitors by the method evaluating the cycling progenitor cells using incorporation of bromodeoxyuridine (BrdUrd) followed by ultraviolet-light cytocide and the other for primitive progenitor cells using a cell sorter with bioactive AT-rich DNA-binding dye Hoechst 33342. In the colonization assay on CFU-S-13 (primitive hematopoietic progenitor cells), the incorporation of BrdUrd starts from a higher percentage with rapid increase in Cx32-KO mice, suggesting suppression of cell cycle in these primitive hematopoietic progenitor cells with Cx32-mediated cell-cycle regulation in the wild-type steady state. This suppression may be attenuated in CFU-S-9, a differentiated progenitor cell compartment. The progenitor cells assayed by in vitro colonization on CFU-GM also showed accelerated cell cycle in the Cx32-KO mice. Following the incorporation of Hoechst 33342, the lineagedepleted bone marrow cells were analyzed by flow cytometry. The population sizes of the LKS fraction obtained were 0.052% in the Cx32-KO bone marrow cells and 0.035% in the wild-type bone marrow cells (p=0.0458<0.05). The lineage-depleted bone marrow cells were analyzed their cell-cycle patterns by flow cytometry, and the G0/G1 was calculated for the LKS fractions in both, the Cx32-KO mice and wild-type mice. The percentage of G0/G1 calculated for the LKS fractions were significantly lower in the Cx32-KO mice than those in wild-type mice (60.6% vs. 87.9% for Cx32-KO vs. wild-type; p=0.001). The results suggest that Cx32 may have suppressive functions on the hematopoietic stem cell compartment, the LKS fraction, under the physiological function of Cx32. The Cx32 in the wild-type mice is, thus considered to be expressed in the primitive hematopoietic stem/progenitor cells to prevent from their exhaustion.

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Transformed Phenotype of Bone Marrow Stromal Cell Lines Derived from K14E7 Fancd2-/- mice

Blood ◽

10.1182/blood.v126.23.4795.4795 ◽

2015 ◽

Vol 126 (23) ◽

pp. 4795-4795

Author(s):

Aranee Sivanathan ◽

Xichen Zhang ◽

Darcy Franicola ◽

Shaonan Cao ◽

Donna Shields ◽

...

Keyword(s):

Bone Marrow ◽

Cell Lines ◽

Stromal Cell ◽

Bone Marrow Stromal Cell ◽

Wild Type ◽

Marrow Stromal Cell ◽

Cytokeratin 14 ◽

E7 Oncogene ◽

Marrow Cultures

Abstract To determine whether cytokeratin 14 promoter linked expression of the Human Papilloma Virus (HPV) oncogene detectably influenced biologic parameters of cell phenotypes other than squamous epithelium, continuous bone marrow cultures were derived from K14E7 Fancd2-/- mice (Park, et al., Cancer Research, 70(23): 9959-9968, 2010). Long-term bone marrow cultures derived from K14E7 Fancd2-/-, control Fancd2-/- (129/Sv), K14E7 (FVB/N), and wild type 129/Sv X FVB/N F1 mice were evaluated for longevity of hematopoiesis in long-term cultures and stromal cell lines were derived from each. Similar to Fancd2-/- mouse, long-term marrow cultures, K14E7 Fancd2-/- marrow cultures demonstrated decreased longevity of hematopoiesis with cessation of production of multi-lineage colony forming progenitor cells after 14 weeks. In contrast, wild type F1 and K14E7 long-term marrow cultures continued to produce hematopoietic cells for a significantly longer duration 25 weeks (p=0.0257). Bone marrow stromal and IL-3 dependent hematopoietic cell lines were derived from each genotype marrow culture. K14E7 Fancd2-/- hematopoietic cells showed reversal of the radiation resistance of Fancd2-/- IL-3 dependent cell lines (D0 of 1.34 ± 0.197Gy, ñ 4.0 ± 0.9 compared to D02.213 ± 0.124 Gy (p = 0.0284), ñ 3.3 ± 0.8. Thus, one phenotypic difference associated with K14E7 oncogene expression was reversal of radioresistance of Fancd2-/- hematopoietic cells. In contrast, bone marrow stromal cell lines from K14E7 Fancd2-/- remained radiosensitive similar to those from Fancd2-/- mice. K14E7 and wild type F1 marrow stromal cell lines showed intermediate radioresistance (p= 0.1759). To determine whether the E6/E7 oncogene had a biological effect in tissues other than squamous epithelium, tissue analysis for cytokeratins 13, 14, 6, and 10 was carried out. Cytokeratin 14 was detected only in squamous cells of the esophagus and oral cavity, not in bone marrow. E6/E7 oncogene was detected only in squamous cell lines expressing cytokeratin 14. However, bone marrow stromal cell lines from K14E7 Fancd2-/- marrow cultures demonstrated a unique phenomenon of cellular density, piling up and formation of tumors in vitro. Each of 22 single cell derived clonal sub-lines of K14E7 Fancd2-/- stromal cell lines demonstrated the same transformed phenotype. These data provide support for indirect effects of the E7 oncogene linked to the K14 promoter in Fancd2-/- hematopoietic and mesenchymal stem cell tissues. Supported by research grant NIAID/NIH, U19A168021. Disclosures No relevant conflicts of interest to declare.

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