A pilot study of single nucleotide polymorphisms in the interleukin-6 receptor and their effects on pre- and post-transplant serum mediator level and outcome after allogeneic stem cell transplantation.

Interleukin (IL)-6 is an important regulator of immunity and inflammation in many diseases. Single nucleotide polymorphisms (SNPs) in the IL-6 gene influence outcome after allogeneic stem cell transplantation (ASCT), but the possible importance of SNPs in the IL-6 receptor has not been examined. We therefore investigated whether SNPs in the IL-6R gene influenced biochemical characteristics and clinical outcomes after ASCT. We examined the IL-6 promoter variant rs1800975 and the IL-6R SNPs rs4453032, rs2228145, rs4129267, rs4845374, rs4329505, rs4845617, rs12083537, rs4845618, rs6698040 and rs4379670 in a 101 population-based cohort of allotransplant recipients and their family donors. Patients being homozygous for the major alleles of the IL-6R SNPs rs2228145 and rs4845618 showed high pretransplant CRP serum levels together with decreased sIL-6R levels; the decreased IL-6R levels persisted 6 months post-transplant. In contrast, patients being homozygous for the minor allele of the IL-6R SNP rs4379670 showed decreased pretransplant CRP levels. Furthermore, the IL-6R rs4845618 donor genotype showed an association with severe acute graft-versus-host disease (GVHD), whereas the donor genotype of the IL-6 SNP rs1800795 was associated with decreased survival 100 days post-transplant. Finally, the recipient genotype of the IL-6R SNP rs4329505 showed a strong association with 2-years non-relapse mortality, and this effect was also highly significant in multivariate analysis. IL-6 and IL-6R SNPs influence the clinical outcome after allogeneic stem cell transplantation.

Differences in proliferative capacity of primary human acute myelogenous leukaemia cells are associated with altered gene expression profiles and can be used for subclassification of patients.

OBJECTIVES: Proliferative capacity of acute myelogenous leukaemia (AML) blasts is important for leukaemogenesis, and we have investigated whether proliferative capacity of primary human AML cells could be used for subclassification of patients. MATERIALS AND METHODS: In vitro proliferative capacity of AML cells derived from two independent groups was investigated. Cells were cultured under highly standardized conditions and proliferation assayed by (3) H-thymidine incorporation after seven days culture. Patients were subclassified by clustering models, and gene expression profile was examined by microarray analyses. RESULTS: Based on proliferative capacity of the AML cells, three different patient clusters were identified: (i) autocrine proliferation that was increased by exogenous cytokines; (ii) detectable proliferation only in presence of exogenous cytokines; and (iii) low or undetectable proliferation even in presence of exogenous cytokines. Patients with highest proliferative capacity cells had no favourable prognostic impact by NPM-1 mutation. Analysis of gene expression profiles showed that the most proliferative cells generally had altered expression of genes involved in regulation of transcription/RNA functions, whereas patients with high proliferative capacity and internal tandem duplications (ITDs) in the FLT3 cytokine receptor gene had altered expression of several molecules involved in cytoplasmic signal transduction. CONCLUSIONS: In vitro proliferative capacity of primary human AML cells was considerably variable between patients and could be used to identify biologically distinct patient subsets.

Hyperleukocytosis and leukocytapheresis in acute leukaemias: experience from a single centre and review of the literature of leukocytapheresis in acute myeloid leukaemia.

BACKGROUND: Hyperleukocytosis is usually defined as leukocyte count >100 × 10(9) L(-1) and can be seen in newly diagnosed leukaemias. Hyperleukocytic leukaemia is associated with a risk of organ failure and early death secondary to leukostasis. Mechanical removal of leukocytes by the apheresis technique, leukocytapheresis, is a therapeutic option in these patients. METHODS: During a 16-year period, 16 patients were treated with leukocytapheresis (35 apheresis procedures) for hyperleukocytosis/leukostasis. We present our experience, and in addition we review previous studies of hyperleukocytosis/leukocytapheresis in patients with acute myeloid leukaemia (AML). RESULTS: We used a highly standardised approach for leukocytapheresis in leukaemia patients with hyperleukocytosis. The average leukocytapheresis number for each patient was 2·2 (range 1-6). Median leukocyte count before apheresis was 309 × 10(9) L(-1) (range 104-935); the mean leukocyte count reduction was 71%, corresponding to a mean absolute reduction of 219 × 10(9) L(-1). No serious side effects were seen during or immediately after apheresis. CONCLUSIONS: The data suggest that our standardised technique for leukocytapheresis effectively reduced the peripheral blood leukaemia cell counts. Previous studies in AML also support the conclusion that this is a safe and effective procedure for the treatment of a potentially life-threatening complication, but apheresis should always be combined with early chemotherapy.

Cyclic AMP can promote APL progression and protect myeloid leukemia cells against anthracycline-induced apoptosis.

We show that cyclic AMP (cAMP) elevating agents protect blasts from patients with acute promyelocytic leukemia (APL) against death induced by first-line anti-leukemic anthracyclines like daunorubicin (DNR). The cAMP effect was reproduced in NB4 APL cells, and shown to depend on activation of the generally cytoplasmic cAMP-kinase type I (PKA-I) rather than the perinuclear PKA-II. The protection of both NB4 cells and APL blasts was associated with (inactivating) phosphorylation of PKA site Ser118 of pro-apoptotic Bad and (activating) phosphorylation of PKA site Ser133 of the AML oncogene CREB. Either event would be expected to protect broadly against cell death, and we found cAMP elevation to protect also against 2-deoxyglucose, rotenone, proteasome inhibitor and a BH3-only mimetic. The in vitro findings were mirrored by the findings in NSG mice with orthotopic NB4 cell leukemia. The mice showed more rapid disease progression when given cAMP-increasing agents (prostaglandin E2 analog and theophylline), both with and without DNR chemotherapy. The all-trans retinoic acid (ATRA)-induced terminal APL cell differentiation is a cornerstone in current APL treatment and is enhanced by cAMP. We show also that ATRA-resistant APL cells, believed to be responsible for treatment failure with current ATRA-based treatment protocols, were protected by cAMP against death. This suggests that the beneficial pro-differentiating and non-beneficial pro-survival APL cell effects of cAMP should be weighed against each other. The results suggest also general awareness toward drugs that can affect bone marrow cAMP levels in leukemia patients.

Synergistic induction of p53 mediated apoptosis by valproic acid and nutlin-3 in acute myeloid leukemia.

Although TP53 mutations are rare in acute myeloid leukemia (AML), wild type p53 function is habitually annulled through overexpression of MDM2 or through various mechanisms including epigenetic silencing by histone deacetylases (HDACs). We hypothesized that co-inhibition of MDM2 and HDACs, with nutlin-3 and valproic acid (VPA) would additively inhibit growth in leukemic cells expressing wild type TP53 and induce p53-mediated apoptosis. In vitro studies with the combination demonstrated synergistic induction of apoptosis in AML cell lines and patient cells. Nutlin-3 and VPA co-treatment resulted in massive induction of p53, acetylated p53 and p53 target genes in comparison with either agent alone, followed by p53 dependent cell death with autophagic features. In primary AML cells, inhibition of proliferation by the combination therapy correlated with the CD34 expression level of AML blasts. To evaluate the combination in vivo, we developed an orthotopic, NOD/SCID IL2rγ(null) xenograft model of MOLM-13 (AML FAB M5a; wild type TP53) expressing firefly luciferase. Survival analysis and bioluminescent imaging demonstrated the superior in vivo efficacy of the dual inhibition of MDM2 and HDAC in comparison with controls. Our results suggest the concomitant targeting of MDM2-p53 and HDAC inhibition, may be an effective therapeutic strategy for the treatment of AML.

Correlation analysis of p53 protein isoforms with NPM1/FLT3 mutations and therapy response in acute myeloid leukemia.

The wild-type tumor-suppressor gene TP53 encodes several isoforms of the p53 protein. However, while the role of p53 in controlling normal cell cycle progression and tumor suppression is well established, the clinical significance of p53 isoform expression is unknown. A novel bioinformatic analysis of p53 isoform expression in 68 patients with acute myeloid leukemia revealed distinct p53 protein biosignatures correlating with clinical outcome. Furthermore, we show that mutated FLT3, a prognostic marker for short survival in AML, is associated with expression of full-length p53. In contrast, mutated NPM1, a prognostic marker for long-term survival, correlated with p53 isoforms ß and γ expression. In conclusion, p53 biosignatures contain useful information for cancer evaluation and prognostication.

Specific cellular signal-transduction responses to in vivo combination therapy with ATRA, valproic acid and theophylline in acute myeloid leukemia.

Acute myeloid leukemia (AML) frequently comprises mutations in genes that cause perturbation in intracellular signaling pathways, thereby altering normal responses to growth factors and cytokines. Such oncogenic cellular signal transduction may be therapeutic if targeted directly or through epigenetic regulation. We treated 24 selected elderly AML patients with all-trans retinoic acid for 2 days before adding theophylline and the histone deacetylase inhibitor valproic acid (ClinicalTrials.gov NCT00175812; EudraCT no. 2004-001663-22), and sampled 11 patients for peripheral blood at day 0, 2 and 7 for single-cell analysis of basal level and signal-transduction responses to relevant myeloid growth factors (granulocyte-colony-stimulating factor, granulocyte/macrophage-colony-stimulating factor, interleukin-3, Flt3L, stem cell factor, erythropoietin, CXCL-12) on 10 signaling molecules (CREB, STAT1/3/5, p38, Erk1/2, Akt, c-Cbl, ZAP70/Syk and rpS6). Pretreatment analysis by unsupervised clustering and principal component analysis divided the patients into three distinguishable signaling clusters (non-potentiated, potentiated basal and potentiated signaling). Signal-transduction pathways were modulated during therapy and patients moved between the clusters. Patients with multiple leukemic clones demonstrated distinct stimulation responses and therapy-induced modulation. Individual signaling profiles together with clinical and hematological information may be used to early identify AML patients in whom epigenetic and signal-transduction targeted therapy is beneficial.

The crosstalk between the matrix metalloprotease system and the chemokine network in acute myeloid leukemia.

Matrix metalloproteinases (MMPs) comprise a large family of zinc-dependent endopeptidases, which are best known for their ability to degrade essentially all components of the extracellular matrix (ECM). By breaking down ECM, MMPs may remove physical barriers, thus allowing cells to migrate and potentially invade other tissues. Recent evidence, however, shows that the proteolytic activities of MMPs also affect several fundamental physiological processes. Primary human acute myeloid leukemia (AML) cells often show constitutive release of several MMPs and chemokines, and there seems to be a crosstalk between the MMP system and the chemokine network. Firstly, the nuclear factor-κB (NF-κB) system represents a common regulator at the transcriptional level both for MMPs (e.g. MMP-1 and MMP-9) and for the constitutive release of several chemokines (CCL2-4/CXCL1/8) by primary human AML cells. Secondly, the crosstalk at the molecular level probably includes MMP-mediated structural alteration and activation of constitutively released chemokines involved in AML cell migration (e.g. CXCL12) and stimulation of bone marrow angiogenesis (e.g. CXCL8). Thirdly, at a functional level the two systems interact because the chemokine network plays a role in similar physiological processes as the MMPs, including AML cell proliferation and migration and local regulation of angiogenesis. Both the chemokine system and MMPs are currently being evaluated as targets in anti-angiogenesis/cancer therapy and may also have potential therapeutic implications in AML. This review introduces the different members of the MMP family and describes their interactions with the chemokine network and the possible involvement of MMPs together with chemokines in leukemogenesis and chemosensitivity in AML.

The chemokine system and its contribution to leukemogenesis and treatment responsiveness in patients with acute myeloid leukemia.

The chemokine family consists of approximately 50 small (8-14 kDa), basic proteins that are expressed and released by a wide range of normal and malignant cells. Most chemokines act through heptahelical transmembrane G protein- coupled receptors. Based on their molecular structure these cytokines are divided into the two major subgroups CCL and CXCL chemokines that bind to CCR or CXCR receptors respectively. Primary human acute myelogenous leukemia (AML) cells show constitutive release of a wide range of chemokines, but the chemokine release profile differs between patients. Among the commonly expressed chemokines are proangiogenic CXCL8, antiangiogenic CXCL4/9-11 and several leukocyte-chemotactic chemokines. Systemic serum levels of leukocyte-chemotactic chemokines depend both on patient age, disease status, the chemotherapy regimen and development of complicating infections. The local chemokine network in human AML is probably further modulated by the hypoxic bone marrow microenvironment and the local release of chemokines by nonleukemic bone marrow stromal cells. Usually primary AML cells also express several chemokine receptors. Specific chemokine inhibitors are now being developed, including chemokine-neutralizing or receptor-blocking antibodies, antisense strategies, receptor-blocking small molecules or inhibitors of downstream signaling. The use of CXCR4-antagonists for mobilization of peripheral blood stem cells has been documented in several clinical studies. Although animal studies suggest that chemokine inhibition also may become useful in the treatment of graft versus host disease, the possible use of chemokine-targeting therapy for other indications than stem cell mobilization requires further studies.

Heat shock protein 90 - a potential target in the treatment of human acute myelogenous leukemia.

Heat shock proteins (HSPs) are molecular chaperones that stabilize folding and conformation of normal as well as oncogenic proteins. These chaperones thereby prevent the formation of protein aggregates. HSPs are often overexpressed in human malignancies, including AML. HSP90 is the main chaperon required for the stabilization of multiple oncogenic kinases involved in the development of acute myelogenous leukemia (AML). HSP90 client proteins are involved in the regulation of apoptosis, proliferation, autophagy and cell cycle progression; several of these proteins are in addition considered as possible therapeutic targets for the treatment of AML. HSP90 inhibition thereby offers the possibility to modulate several intracellular regulatory pathways through targeting of a single molecule. Several direct inhibitors of HSP90 have been developed, and they are classified into four groups: benzoquinon ansamycines and their derivatives, radicicol and its derivates, small synthetic inhibitors and a final group of other inhibitors. The HSP90 activity is regulated by posttranscriptional modulation; HSP90 inhibition can thereby be indirectly achieved through increased acetylation caused by histone deacetylase inhibitors. Many of these agents have entered phase I/II clinical trials, and the results from these initial studies have documented that HSP90 inhibition can mediate antileukemic effects in vivo. However, one would expect immunosuppressive side effects because HSP90 inhibitors have both direct and indirect inhibitory effects on T cell activation. Thus, future clinical studies are needed to clarify the efficiency and toxicity of HSP90 inhibitors in the treatment of human AML, including studies where HSP90 inhibitors are combined with conventional chemotherapy.

Review: genetic models of acute myeloid leukaemia.

The use of genetically engineered mice (GEM) have been critical in understanding disease states such as cancer, and none more so than acute myelogenous leukaemia (AML), a disease characterized by over 100 distinct chromosomal translocations. A substantial proportion of cases exhibiting recurrent reciprocal translocations at diagnosis, such as t(8;21) or t(15;17) have been exhaustively studied and are currently employed in clinical diagnosis. However, a definitive conclusion regarding the leukaemogenic potential of defined transgenes for this disease remains elusive. While it is increasingly apparent that a number of cooperating mutations are necessary to develop a leukaemic phenotype, the number of models reflecting these synergisms remains few. Furthermore, little emphasis has been paid to the effect of chromosomal translocations other than recurrent genetic abnormalities, with no models reflecting the multiple abnormalities observed in high-risk cases of AML accounting for 8-10% of adult AML. Here we review the differing technologies employed in generation of GEM of AML. We discuss the relevance of GEM AML from embryonic stem cell-mediated (for example retinoic acid receptor-alpha fusions and AML1/ETO) models; through to the valuable retroviral-mediated gene transfer models. The latter have been used to great effect in defining the transforming properties of chromosomal translocation products such as MLL (found in 5-6% of all AML cases) and NUP98 (denoting poor prognosis in therapy-related disease) and particularly when co-transduced with bad prognostic factors such as Flt3 mutations. Finally, we comment on the emergence of newer transduction technologies, which can regulate the level of expression to defined cell lineages in both primary murine and human xenografts, and discuss how combining multiple genetic modalities, more relevant models of this complex disease are being generated.

Release of angiopoietin-1 by primary human acute myelogenous leukemia cells is associated with mutations of nucleophosmin, increased by bone marrow stromal cells and possibly antagonized by high systemic angiopoietin-2 levels.

The balance between proangiogenic Angiopoietin-1 (Ang-1) and the antagonistic Ang-2 is important both for leukemogenesis and chemosensitivity in human acute myelogenous leukemia (AML). We examined the release of Ang-1 and Ang-2 by AML cells cultured alone and in cocultures with stromal cells. Detectable Ang-1 release from AML cells was observed for most patients (62/91), whereas Ang-2 release was detected only for a minority (23/91). Coculture of AML and stromal cells led to increased Ang-1 levels. Furthermore, the role of the angiopoietin system was investigated by characterizing whether the differences in angiopoietin expression in AML patients can be related to nucleophosmin (NPM1) mutations. We compared the gene expression profiles of AML cells derived from 19 patients with FLT3 mutations and normal cytogenetics with and without NPM1 mutations and observed increased expression of Ang-1 in patients with NPM1 mutations. Finally, we found significantly higher Ang-2 levels in serum of AML patients compared with healthy controls. Our results suggest that AML cells are a major source of Ang-1 in leukemic bone marrow, especially in patients with NPM1 mutations, but the local levels are also influenced by stromal cells. Local Ang-2 release from AML cells is less common, but high systemic levels of Ang-2 may affect bone marrow angioregulation.

Histone deacetylase inhibitors in cancer treatment: a review of the clinical toxicity and the modulation of gene expression in cancer cell.

Characterization of epigenetic events in carcinogenesis has led to the discovery of a new class of oncogenes and thereby a new class of therapeutic targets. Among the new therapeutic approaches are modulation of protein lysine acetylation through inhibition of histone deacetylases (HDACs). HDACs deacetylate histones as well as transcription factors and can modulate gene expression through both these mechanisms in normal and malignant cells. Furthermore, acetylation is an important posttranslational modulation of several proteins involved in the regulation of cell proliferation, differentiation and apoptosis in normal as well as cancer cells. Even though several HDAC inhibitors have been characterized in vitro, only a limited number of these agents are in clinical trials. Various HDAC inhibitors differ in their toxicity profile when comparing the side effects described in the available clinical studies of HDAC inhibition in the treatment of cancer. These drugs may also affect normal hematopoiesis; hematologic toxicity is common to many drugs but stimulation of hematopoiesis seems to occur for others. HDAC inhibitors usually affect <10% of the genes in cancer cells. Divergent effects of HDAC inhibition on the global gene expression profiles have been described when testing various cancer cells, and this is further complicated by altered HDAC expression induced by HDAC inhibitors. However, increased p21 expression seems to be a common characteristic for most studies, suggesting an important role of this molecule during HDAC inhibitory treatment. Even though the initial studies are encouraging, additional in vitro and in vivo pharmacological characterization is definitely needed.

Serum levels of angioregulatory mediators in healthy individuals depend on age and physical activity: studies of angiogenin, basic fibroblast growth factor, leptin and endostatin.

OBJECTIVE: Angiogenesis is regulated by a wide range of soluble mediators that are released locally or by distant organs that affect local angiogenesis through variations in systemic levels. Serum levels of angioregulatory mediators are important for muscle angiogenesis in response to physical activity; in addition, angioregulation is involved in disease development, and determination of systemic levels may therefore be useful in future clinical practice. The aim of the present study was to investigate whether physical activity alters systemic levels of angioregulatory mediators in healthy individuals. MATERIAL AND METHODS: The effects of physical activity on serum levels of pro- (angiogenin, basic fibroblast growth factor (bFGF), leptin) and antiangiogenic (endostatin) mediators were investigated. The levels were determined immediately before and after activity for healthy young athletes (all males, age 18 years) and elderly individuals (9 M, 11 F, age 68-88 years). RESULTS: Elderly individuals showed higher pre-activity levels than the athletes for all mediators. The young athletes showed increased angiogenin and endostatin levels and decreased bFGF levels after 45 min of intensive physical activity, whereas leptin levels were not altered. Elderly individuals showed a similar decrease in bFGF levels after a 3-h mountain walk, but angiogenin, endostatin and leptin levels were not altered. CONCLUSIONS: Serum levels of angioregulatory mediators depend on age, and standardization of physical activity prior to sampling will probably be necessary when evaluating the possible clinical use of these parameters.

The viability of cryopreserved PBPC depends on the DMSO concentration and the concentration of nucleated cells in the graft.

BACKGROUND: DMSO is widely used as a cryoprotectant for PBPC. It is desirable to reduce the amount of DMSO without jeopardizing the quality of the stem cell product. The present study was undertaken to investigate whether recovery and survival of CD34+ cells would be significantly altered when PBPC used for autologous transplantations were cryopreserved with four different DMSO concentrations. METHODS: Apheresis samples of PBPC from 20 consecutive patients were mixed in parallel with 2%, 4%, 5% and 10% DMSO, frozen with identical cell concentrations at a controlled rate, and stored in liquid nitrogen for 6-8 weeks. PBPC samples from 11 consecutive patients were also cryopreserved with two different cell concentrations (150 and 300 x 10(6) nucleated cells/mL) to investigate the effect of increasing the cell concentrations while decreasing the DMSO concentration. The flow cytometric absolute count method, based on ISHAGE guidelines, was used to measure the absolute count of total and viable CD34+ cells in the post-thaw samples. RESULTS: PBPC cryopreserved at 150 x 10(6) cells/mL with 2% DMSO yielded significantly inferior CD34+ cell recovery (P < 0.001) and survival (P < 0.001) compared with cryopreservation with 4% and 5% DMSO. This was also observed when comparing higher cell concentrations. However, a reduced cell survival (P = 0.02) was observed when the nucleated cell concentration was increased from 150 to 300 x 10(6) cells/mL in samples cryopreserved with 5% DMSO. DISCUSSION: We conclude that 5% DMSO may be the optimal dose for cryopreserving PBPC as long as the cells have not been concentrated at much more than 200 x 10(6) nucleated cells/mL.

Animal models of acute myelogenous leukaemia - development, application and future perspectives.

From the early inception of the transplant models through to contemporary genetic and xenograft models, evolution of murine leukaemic model systems have been critical to our general comprehension and treatment of cancer, and, more specifically, disease states such as acute myelogenous leukaemia (AML). However, even with modern advances in therapeutics and molecular diagnostics, the majority of AML patients die from their disease. Thus, in the absence of definitive in vitro models which precisely recapitulate the in vivo setting of human AMLs and failure of significant numbers of new drugs late in clinical trials, it is essential that murine AML models are developed to exploit more specific, targeted therapeutics. While various model systems are described and discussed in the literature from initial transplant models such as BNML and spontaneous murine leukaemia virus models, to the more definitive genetic and clinically significant NOD/SCID xenograft models, there exists no single compendium which directly assesses, reviews or compares the relevance of these models. Thus, the function of this article is to provide clinicians and experimentalists a chronological, comprehensive appraisal of all AML model systems, critical discussion on the elucidation of their roles in our understanding of AML and consideration to their efficacy in the development of AML chemotherapeutics.

Large-volume leukapheresis yields more viable CD34+ cells and colony-forming units than normal-volume leukapheresis, especially in patients who mobilize low numbers of CD34+ cells.

BACKGROUND: Large-volume leukapheresis (LVL) differs from normal-volume leukapheresis (NVL) by increased blood flow and altered anticoagulation regimen. LVL is now regarded as a safe procedure for collection of peripheral blood progenitor cells (PBPCs), but it is not known whether the procedure will alter CD34+ cell quality or will be useful for patients who mobilize few CD34+ cells into peripheral blood. STUDY DESIGN AND METHODS: The results from 82 LVL and 125 NVL (4.0-5.3 and 2.7-3.5 times the patients' blood volumes processed, respectively) were retrospectively analyzed in altogether 112 consecutive patients with malignant diseases. RESULTS: The LVL yielded significantly more CD34+ cells (4.2 x 10(6) vs. 3.1 x 10(6)/kg, p = 0.006, all patients; and 1.8 x 10(6) vs. 1.3 x 10(6)/kg, p = 0.004, bad mobilizers) and significantly higher colony-forming units (77 x 10(4) vs. 33 x 10(4)/kg; all patients and 33 x 10(4) vs. 20 x 10(4)/kg, p < 0.001, both groups). Significantly fewer leukapheresis procedures were required to obtain 2 x 10(6) CD34+ cells per kg (one vs. two, p = 0.001, all patients; and two vs. three, p = 0.009, bad mobilizers). No significant differences in CD34+ cell viability and time to hematologic recovery were observed between the patients who received PBPCs harvested by NVL and LVL. CONCLUSION: Although a median platelet loss of 36 percent can be expected, LVL can be recommended as the standard apheresis method for PBPC collections in patients with malignant diseases. LVL is particularly useful in patients who mobilize a low number of CD34+ cells into the peripheral blood.