Synchrony of telomere length among hematopoietic cells.

Objective: Little is known about the relationship of telomere length among leukocyte subsets and cells up the hematopoietic hierarchy. This information is relevant because telomere dynamics in granulocytes were postulated to mirror those of hematopoietic stem cells (HSCs).

Materials And Methods: In newborn umbilical cord blood (UCB), we examined the relationships of telomere length in hematopoietic progenitor cells (HPCs) (CD34(+)CD45(-)) with those in T lymphocytes and granulocytes.

Targeted therapy of human osteosarcoma with 17AAG or rapamycin: characterization of induced apoptosis and inhibition of mTOR and Akt/MAPK/Wnt pathways.

Osteosarcoma is highly resistant to current chemotherapy regimens. Novel therapeutic approaches, potentially involving targeting of specific survival pathways, are needed. We used 17-AAG to inhibit Hsp90 and rapamycin to inhibit mTOR, in the osteosarcoma cell lines, HOS and KHOS/NP.

Protein disulphide isomerase in platelet function.

Platelet protein disulphide isomerase (PDI) has a role in platelet aggregation, probably targeting a thiol-containing platelet surface protein. The thiol-containing P2Y(12) ADP receptor is involved in aggregation induced by most agonists and may be the target of PDI. By excluding the P2Y(12) pathway and using the anti-PDI antibody RL90 this study showed that PDI targets a non-P2Y(12) thiol-protein in aggregation.

Improved mobilization of peripheral blood CD34+ cells and dendritic cells by AMD3100 plus granulocyte-colony-stimulating factor in non-Hodgkin's lymphoma patients.

AMD3100 is a drug capable of mobilizing peripheral blood stem cells (PBSCs) in donors and in cancer patients as a single agent or in combination with granulocyte-colony-stimulating factor (G-CSF). We initiated a phase II study of 11 refractory or relapsed non-Hodgkin's lymphoma (NHL) patients, receiving 16 microg/kg daily of G-CSF for 4 days followed by 240 microg/kg of AMD3100 given subcutaneously on a new schedule of 9-10 h before apheresis collection on day 5. Our aims were to assess the effect of AMD3100 on the mobilization of CD34+ cells, dendritic cells (DCs) and lymphoma cells.

Arsenic trioxide induces p53-dependent apoptotic signals in myeloma cells with SiRNA-silenced p53: MAP kinase pathway is preferentially activated in cells expressing inactivated p53.

Mutations in p53 are the most common genetic abnormality in cancers. Arsenic trioxide (ATO) is an effective chemotherapeutic agent for the treatment of acute promyelocytic leukemia (APL) and is being tested in phase II studies in various types of cancers. We have shown that ATO is a potent inducer of apoptosis in multiple myeloma cells, engaging primarily the intrinsic apoptotic pathway in cells expressing w.

A phase II trial with gemcitabine and paclitaxel for the treatment of refractory and relapsed multiple myeloma patients.

Multiple myeloma (MM) is an incurable disease with a 10-year survival of <20%. We have previously shown that the combination of gemcitabine and paclitaxel acts synergistically to induce apoptosis of myeloma cells in vitro. Based on these preclinical studies and phase I-II clinical trials in patients with solid tumors, we initiated a phase II clinical trial of paclitaxel 150 mg/m(2) IV over 3 h followed by gemcitabine 3000 mg/m(2) IV over 30-60 min in patients with relapsed or refractory MM.

Granulocyte colony-stimulating factor mobilizes more dendritic cell subsets than granulocyte-macrophage colony-stimulating factor with no polarization of dendritic cell subsets in normal donors.

Dendritic cells (DCs) are effective antigen-presenting cells. We hypothesized that increasing the DC populations in donor lymphocyte infusions (DLIs) may augment the graft versus malignancy effect, particularly if granulocyte-macrophage colony-stimulating factor (GM-CSF) mobilization resulted in increased precursor dendritic cell (pDC) 1 cells. Mature DCs, pDC1 cells, pDC2 cells, and CD34(+) cells from the same donor were compared after granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cell collections and GM-CSF mobilized DLI collections.

No polarization of type 1 or type 2 precursor dendritic cells in peripheral blood stem cell collections of non-hodgkin's lymphoma patients mobilized with cyclophosphamide plus G-CSF, GM-CSF, or GM-CSF followed by G-CSF.

Dendritic cells (DCs) are the most efficient antigen-presenting cells and play a role in immune reconstitution after autologous transplantation. Recent reports suggest that mobilization with granulocyte colony-stimulating factor (G-CSF) containing regimens polarizes DCs into pDC2, which could potentially result with increased Th2 response and decreased graft-versus-host disease (GVHD) in allogeneic transplantation and with decreased cytotoxic Th1 response and graft versus tumor effect, which in autologous transplantation could translate into increased relapse rate. Previously, we have shown that non-Hodgkin's lymphoma (NHL) patients receiving cyclophosphamide (CTX) plus granulocyte- macrophage (GM)-CSF, G-CSF or GM-CSF followed by G-CSF for stem cell collection, mobilize up to five-fold more mature CD80(+) DCs compared to CTX plus G-CSF mobilized patients.

Arsenic trioxide: an anti cancer missile with multiple warheads.

The proven efficacy of ATO in the treatment of APL and the emerging importance of ATO in other diseases prompted extensive studies of the mechanisms of action of ATO in APL and in other types of cancers. In this review we will focus on downstream events in ATO-induced intrinsic and extrinsic apoptotic pathways with an emphasis on the role of pro-apoptotic and anti-apoptotic proteins and the role of p53 in ATO-induced apoptosis including its effect on cell cycle, its anti-mitotic effect and the role of apoptosis inducing factors (AIF) in ATO-induced apoptosis, chromatin condensation and nuclear fragmentation in myeloma cells as a model.

Arsenic trioxide and paclitaxel induce apoptosis by different mechanisms.

Arsenic trioxide (ATO) and paclitaxel (TAXOL) are effective in the treatment of various types of cancers. Both drugs induce G2/M arrest. We have previously shown that ATO is a potent inducer of apoptosis in myeloma cells expressing mutant p53 engaging both the intrinsic and extrinsic apoptotic pathways.

Mobilization of myeloma cells involves SDF-1/CXCR4 signaling and downregulation of VLA-4.

Adhesion molecules and stromal cell-derived factor-1 (SDF-1)/CXCR4 signaling play key roles in homing and mobilization of hematopoietic stem cells (HSC). Active signaling through SDF-1/CXCR4 and upregulation of adhesion molecules are required for homing, whereas downregulation of adhesion molecules and disruption of SDF-1/CXCR4 signaling are required for mobilization of HSC. We studied the surface expression of CXCR4 very late activation antigen (VLA)-4 and VLA-5 on myeloma cells mobilized with cyclophosphamide and GM-CSF in 12 multiple myeloma patients undergoing HSC mobilization for autologous transplantation.

Homing and mobilization of hematopoietic stem cells and hematopoietic cancer cells are mirror image processes, utilizing similar signaling pathways and occurring concurrently: circulating cancer cells constitute an ideal target for concurrent treatment with chemotherapy and antilineage-specific antibodies.

Adhesion molecules and stromal cell-derived factor-1 (SDF-1)/CXCR4 signaling play key role in homing and mobilization of hematopoietic progenitor (HPC) and hematopoietic cancer clonogenic cells (HCC). High expression of VLA-4 is required for homing of HPC and HCC, whereas downregulation of these molecules is required for successful mobilization of HPC and HCC. Upregulation and activation of the SDF-1/CXCR4 signaling is required for homing of HPC and HCC, whereas disruption of the SDF-1 signaling is required for mobilization of HPC and HCC.

Arsenic trioxide selectively induces early and extensive apoptosis via the APO2/caspase-8 pathway engaging the mitochondrial pathway in myeloma cells with mutant p53.

Arsenic trioxide (ATO) is effective in the treatment of acute promyelocytic leukemia (APL) and induces apoptosis in APL cells and in a great variety of other cancer cells. We have previously shown that ATO induces apoptosis in myeloma cells in two different modes depending on p53 status in the cells. In cells expressing mutated p53, ATO induced, G2/M arrest and activation caspase 8 and 3 and rapid and extensive apoptosis.

Arsenic trioxide-induced apoptosis in myeloma cells: p53-dependent G1 or G2/M cell cycle arrest, activation of caspase-8 or caspase-9, and synergy with APO2/TRAIL.

Arsenic trioxide (ATO) has been shown to induce differentiation and apoptosis in acute promyelocytic leukemia (APL) cells concomitant with down-regulation of the PML-RARalpha fusion protein, a product of the t(15:17) translocation characteristic of APL leukemic cells. However, ATO is also a potent inducer of apoptosis in a number of other cancer cells lacking the t(15:17) translocation. The exact mechanism of ATO-induced apoptosis in these cells is not yet clear.

Potentiation of dexamethasone-, paclitaxel-, and Ad-p53-induced apoptosis by Bcl-2 antisense oligodeoxynucleotides in drug-resistant multiple myeloma cells.

Overexpression of Bcl-2 in myeloma cells results in resistance to drugs such as dexamethasone (DEX), adenovirus-mediated delivery of p53 (Ad-p53), and paclitaxel (TAX), which work through the intrinsic apoptotic pathway. Bcl-2 antisense oligodeoxynucleotides (Bcl-2-ASO) have been shown to induce apoptosis in cancer cells, as a single agent or, better, in combination with chemotherapy. We hypothesized that down-regulation of Bcl-2 by Bcl-2-ASO will sensitize drug-resistant myeloma cells to undergo apoptosis.

Comparison between granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor in the mobilization of peripheral blood stem cells.

Peripheral blood stem cells (PBSC) have become the preferred source of stem cells for autologous transplantation because of the technical advantage and the shorter time to engraftment. Mobilization of CD34+ into the peripheral blood can be achieved by the administration of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), or both, either alone or in combination with chemotherapy. G-CSF and GM-CSF differ somewhat in the number and composition of PBSCs and effector cells mobilized to the peripheral blood.

Antisense inhibition of macrophage inflammatory protein 1-alpha blocks bone destruction in a model of myeloma bone disease.

We recently identified macrophage inflammatory protein 1-alpha (MIP-1alpha) as a factor produced by multiple myeloma (MM) cells that may be responsible for the bone destruction in MM (1). To investigate the role of MIP-1alpha in MM bone disease in vivo, the human MM-derived cell line ARH was stably transfected with an antisense construct to MIP-1alpha (AS-ARH) and tested for its capacity to induce MM bone disease in SCID mice. Human MIP-1alpha levels in marrow plasma from AS-ARH mice were markedly decreased compared with controls treated with ARH cells transfected with empty vector (EV-ARH).

Additive effect of Apo2L/TRAIL and Adeno-p53 in the induction of apoptosis in myeloma cell lines.

Objective: We have previously shown that Adenovirus-p53 (Ad-p53) is a potent inducer of apoptosis in myeloma cells expressing nonfunctional p53 and low levels of bcl-2 and that Apo2L/TRAIL is a potent inducer of apoptosis, independent of bcl-2. A study was designed to test the synergy between Ad-p53 and Apo2L/TRAIL in the induction of apoptosis in relation to the expression of DR4/DR5 and DcR1, in cells undergoing Ad-p53-induced apoptosis.

Methods: Replication deficient Ad-p53 and human recombinant Apo2L/TRAIL were used.

Myeloablation and autologous peripheral blood stem cell rescue results in hematologic and clinical responses in patients with myeloid metaplasia with myelofibrosis.

Current therapeutic options for myeloid metaplasia with myelofibrosis (MMM) are limited. A pilot study was conducted of autologous peripheral blood stem cell (PBSC) collection in 27, followed by transplantation in 21 patients with MMM. The median age was 59 (range 45-75) years.

Recent developments in the regulation of peripheral blood stem cell mobilization and engraftment by cytokines, chemokines, and adhesion molecules.

Peripheral blood stem cells (PBSC) have become the preferred source of stem cells for autologous transplantation because of the technical advantage and the shorter time to engraftment. Administration of hematopoietic growth factors such as granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) results in mobilization of PBSCs into the peripheral blood. G-CSF and GM-CSF differ somewhat in the number and composition of CD34(+) cells and effector cells mobilized to the peripheral blood; however, the molecular mechanism underlying the release and engraftment of CD34(+) cells by these growth factors is poorly understood.

Mobilization of dendritic cells and NK cells in non-Hodgkin's lymphoma patients mobilized with different growth factors.

Conflicting results have been reported regarding the effect of various growth factors on the mobilization of natural killer (NK) cells and dendritic cells in patients undergoing stem cell mobilization for autotransplantation. We compared the extent of mobilization of NK cells and dendritic cells in non-Hodgkin's (NHL) patients undergoing mobilization with granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage (GM)-CSF, or GM-CSF followed by G-CSF. Overall, 35 patients were studied.

Differential mobilization of CD34+ cells and lymphoma cells in non-Hodgkin's lymphoma patients mobilized with different growth factors.

Co-mobilization of CD34(+) cells and tumor has been documented in patients with different types of cancer undergoing peripheral blood stem cell transplantation (PBSCT). Conflicting reports were published regarding the role of various growth factors in tumor cells mobilization, hence we studied the extent of CD34(+) cells and lymphoma cell mobilization in 35 non-Hodgkin's (NHL) patients primed by cyclophosphamide (Cy) in combination with granulocyte colony-stimulating factor (GCSF) (A, 13 patients), granulocyte-macrophage (GM)-CSF (B, 10 patients), or GM-CSF followed by G-CSF (C, 12 patients). CD34(+) cells were quantitated by flow cytometry and lymphoma cells by the TaqMan Real Time PCR for bcl-2 gene rearrangement.

A new molecular role for iron in regulation of cell cycling and differentiation of HL-60 human leukemia cells: iron is required for transcription of p21(WAF1/CIP1) in cells induced by phorbol myristate acetate.

To investigate the role of iron in hematopoiesis, we studied effects of iron deprivation on PMA-induced monocyte/macrophage differentiation in HL-60 cells. Iron deprivation induced by desferrioxamine (DF) blocked PMA-induced differentiation and induced S-phase arrest and apoptosis in up to 60% of cells. Apoptosis was not related to a decrease of bcl-2 or to c-myc overexpression.

Expression of adhesion molecules on CD34(+) cells in peripheral blood of non-hodgkin's lymphoma patients mobilized with different growth factors.

Adhesion molecules on CD34(+) cells were implicated in the process of peripheral blood stem cell (PBSC) mobilization and homing. We studied the mobilization of CD34(+)Thy1(+) cells, CD34(+) very late-acting antigen (VLA)4(+) cells, and CD34(+)L-selectin(+) cells in non-Hodgkin's lymphoma patients mobilized with cyclophosphamide plus G-CSF, GM-CSF, or GM-CSF followed by G-CSF. The mean percentage of CD34(+) cells in the bone marrow (BM) expressing Thy1 was 23.

Plasma levels of SDF-1 and expression of SDF-1 receptor on CD34+ cells in mobilized peripheral blood of non-Hodgkin's lymphoma patients.

CXCR4 is the receptor for the chemokine stromal derived factor-1 (SDF-1), is expressed on CD34+ cells, and has been implicated in the process of CD34+ cell migration and homing. We studied the mobilization of CD34/CXCR4 cells and the plasma levels of SDF-1 and flt3-ligand (flt3-L) in 36 non-Hodgkin's lymphoma patients receiving cyclophosphamide (Cy) plus G-CSF (arm A), Cy plus GM-CSF (arm B), or Cy plus GM-CSF followed by G-CSF (arm C) for peripheral blood stem cell (PBSC) mobilization and autotransplantation. We observed lower plasma levels of SDF-1 in PBSCs compared to premobilization bone marrow samples.