Increased bone marrow microvascular density in haematological malignancies is associated with differential regulation of angiogenic factors

Hematopoietic and leukemic stem cells homeostasis: the role of bone marrow niche

The bone marrow microenvironment (BMM) has highly specialized anatomical characteristics that provide a sanctuary place for hematopoietic stem cells (HSCs) that allow appropriate proliferation, maintenance, and self-renewal capacity. Several cell types contribute to the constitution and function of the bone marrow niche. Interestingly, uncovering the secrets of BMM and its interaction with HSCs in health paved the road for research aiming at better understanding the concept of leukemic stem cells (LSCs) and their altered niche. In fact, they share many signals that are responsible for interactions between LSCs and the bone marrow niche, due to several biological similarities between LSCs and HSCs. On the other hand, LSCs differ from HSCs in their abnormal activation of important signaling pathways that regulate survival, proliferation, drug resistance, invasion, and spread. Targeting these altered niches can help in better treatment choices for hematological malignancies and bone marrow disorders in general and acute myeloid leukemia (AML) in particular. Moreover, targeting those niches may help in decreasing the emergence of drug resistance and lower the relapse rate. In this article, the authors reviewed the most recent literature on bone marrow niches and their relations with either normal HSCs and AML cells/LSC, by focusing on pathogenetic and therapeutic implications.

A prognostic model incorporating inflammatory cells and cytokines for newly diagnosed multiple myeloma patients

Peripheral blood cell counts and cytokines can be used as predictors of multiple myeloma (MM) patients' outcomes. 313 newly diagnosed MM patients treated with novel agents were divided into training and validation cohorts. We selected the common peripheral blood cell counts, including the lymphocyte/monocyte ratio (LMR), neutrophil/lymphocyte ratio (NLR), and platelet/lymphocyte ratio (PLR), systemic inflammation response index (SIRI), and serum cytokines which contained tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-2 receptor (IL-2R), interleukin-8 (IL-8), interleukin-6 (IL-6), and interleukin-10 (IL-10) as related variables. The least absolute shrinkage and selection operator (LASSO) regression was conducted to sort the predictor variables in the training cohort, and then the developed nomogram was assessed in the training and validation cohort. Our study showed that SIRI, PLR, and IL-8 were independent prognostic factors for the survival of MM patients. Patients with lower SIRI (≤ 0.87) had superior survival than patients with higher SIRI (> 0.87). Further, according to the LASSO regression, a nomogram embracing LMR (> 3.78), SIRI (> 0.87), PLR (≤ 106.44), and IL-8 was established. The nomogram demonstrated a better correlation with the outcomes of MM patients in the training cohort than International Staging System (ISS) and Revised-International Staging System (R-ISS). The same results were verified in the validation cohort. The nomogram incorporating inflammatory cells and cytokines could be a helpful tool to stratify MM patients in the era of novel agents.

Angiogenesis, coagulation, and fibrinolytic markers in acute promyelocytic leukemia (NB4): An evaluation of melatonin effects

Melatonin is a powerful biological agent that has been shown to inhibit angiogenesis and also exerts anti-inflammatory effects. It is well known that new blood vessel formation (angiogenesis) has become an urgent issue in leukemia as well as solid tumors. Acute promyelocytic leukemia (APL) is a form of liquid cancer that manifests increased angiogenesis in the bone marrow of patients. Despite high-rate curable treatment with all-trans-retinoic acid (ATRA) and recently arsenic-trioxide (ATO), early death because of hemorrhage, coagulopathy, and Disseminated intravascular coagulation (DIC) remains still a concerning issue in these patients. It is, therefore, urgent to seek treatment strategies with antiangiogenic capabilities that also diminish coagulopathy and hyperfibrinolysis in APL patients. In this study, a coculture system with human umbilical vein endothelial cells (HUVECs) and NB4 APL cells was used to investigate the direct effect of melatonin on angiogenesis and its possible action on tissue factor (TF) and tissue-type plasminogen activator-1 (TPA-1) expression. Our experiments revealed that HUVEC-induced angiogenesis by cocultured NB4 cells was suppressed when melatonin alone or in combination with ATRA was added to the incubation medium. Melatonin at concentrations of 1 mM inhibited tube formation of HUVECs and also decreased interleukin-6 secretion and VEGF mRNA expression in HUVEC and NB4 cells. Taken together, the results of this study demonstrate that melatonin inhibits accelerated angiogenesis of HUVECs and ameliorates the coagulation and fibrinolysis indices stimulated by coculturing with NB4 cells.

The cytokine network in acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly heterogeneous malignancy of the blood and bone marrow, characterized by clonal expansion of myeloid stem and progenitor cells and rapid disease progression. Chemotherapy has been the first-line treatment for AML for more than 30 years. Application of recent high-throughput next-generation sequencing technologies has revealed significant molecular heterogeneity to AML, which in turn has motivated efforts to develop new, targeted therapies. However, due to the high complexity of this disease, including multiple driver mutations and the coexistence of multiple competing tumorigenic clones, the successful incorporation of these new agents into clinical practice remains challenging. These continuing difficulties call for the identification of innovative therapeutic approaches that are effective for a larger cohort of AML patients. Recent studies suggest that chronic immune stimulation and aberrant cytokine signaling act as triggers for AML initiation and progression, facets of the disease which might be exploited as promising targets in AML treatment. However, despite the greater appreciation of cytokine profiles in AML, the exact functions of cytokines in AML pathogenesis are not fully understood. Therefore, unravelling the molecular basis of the complex cytokine networks in AML is a prerequisite to develop new therapeutic alternatives based on targeting cytokines and their receptors.

Bone Marrow Niches of Hematopoietic Stem and Progenitor Cells

The mammalian hematopoietic system is remarkably efficient in meeting an organism’s vital needs, yet is highly sensitive and exquisitely regulated. Much of the organismal control over hematopoiesis comes from the regulation of hematopoietic stem cells (HSCs) by specific microenvironments called niches in bone marrow (BM), where HSCs reside. The experimental studies of the last two decades using the most sophisticated and advanced techniques have provided important data on the identity of the niche cells controlling HSCs functions and some mechanisms underlying niche-HSC interactions. In this review we discuss various aspects of organization and functioning of the HSC cell niche in bone marrow. In particular, we review the anatomy of BM niches, various cell types composing the niche, niches for more differentiated cells, metabolism of HSCs in relation to the niche, niche aging, leukemic transformation of the niche, and the current state of HSC niche modeling in vitro.

Therapeutic Interaction of Apatinib and Chidamide in T-Cell Acute Lymphoblastic Leukemia through Interference with Mitochondria Associated Biogenesis and Intrinsic Apoptosis

T-cell acute lymphoblastic leukemia (T-ALL) shows poor clinical outcome and has limited therapeutic options, indicating that new treatment approaches for this disease are urgently required. Our previous study demonstrated that apatinib, an orally selective VEGFR-2 antagonist, is highly effective in T-ALL. Additionally, chidamide, a histone deacetylase inhibitor, has proven to be cytotoxic against T-ALL in preclinical and clinical settings. However, whether the therapeutic interaction of apatinib and chidamide in T-ALL remains unknown. In this study, apatinib and chidamide acted additively to decrease cell viability and induce apoptosis in T-ALL in vitro. Notably, compared with apatinib or chidamide alone, the combinational regimen was more efficient in abrogating the leukemia burden in the spleen and bone marrow of T-ALL patient-derived xenograft (PDX) models. Mechanistically, the additive antileukemia effect of apatinib and chidamide was associated with suppression of mitochondrial respiration and downregulation of the abundance levels of several rate-limiting enzymes that are involved in the citric acid cycle and oxidative phosphorylation (OXPHOS). In addition, apatinib enhanced the antileukemia effect of chidamide on T-ALL via activation of the mitochondria-mediated apoptosis pathway and impediment of mitochondrial biogenesis. Taken together, the study provides a potential role for apatinib in combination with chidamide in the management of T-ALL and warrants further clinical evaluations of this combination in patients with T-ALL.

Leukemia stem cell-bone marrow microenvironment interplay in acute myeloid leukemia development

Despite the advances in intensive chemotherapy regimens and targeted therapies, overall survival (OS) of acute myeloid leukemia (AML) remains unfavorable due to inevitable chemotherapy resistance and high relapse rate, which mainly caused by the persistence existence of leukemia stem cells (LSCs). Bone marrow microenvironment (BMM), the home of hematopoiesis, has been considered to play a crucial role in both hematopoiesis and leukemogenesis. When interrupted by the AML cells, a malignant BMM formed and thus provided a refuge for LSCs and protecting them from the cytotoxic effects of chemotherapy. In this review, we summarized the alterations in the bidirectional interplay between hematopoietic cells and BMM in the normal/AML hematopoietic environment, and pointed out the key role of these alterations in pathogenesis and chemotherapy resistance of AML. Finally, we focused on the current potential BMM-targeted strategies together with future prospects and challenges. Accordingly, while further research is necessary to elucidate the underlying mechanisms behind LSC–BMM interaction, targeting the interaction is perceived as a potential therapeutic strategy to eradicate LSCs and ultimately improve the outcome of AML.

Elevation of miR-302b prevents multiple myeloma cell growth and bone destruction by blocking DKK1 secretion

BACKGROUND

Myeloma bone disease (MBD) is a severe complication of multiple myeloma (MM) mainly due to an imbalance between enhanced osteoclast activity and reduced osteoblast function. Previous studies have demonstrated that miRNAs play a vital role in the osteogenic differentiation of mesenchymal stromal cells (MSCs) in MM. However, the value of miR‑302b in MBD remains to be further elucidated. The aim of this study is to explore the role of miR‑302b in the regulation of MBD osteogenic differentiation and evaluate the potential of a new therapeutic strategy for the clinical treatment of MBD.

METHOD

Our previous research demonstrated that MiR-302b belongs to the miR-302 cluster and is able to inhibit tumor growth and osteolysis in an orthotopic osteosarcoma xenograft tumor mouse model. In this study, we first transfected miR-302b mimics, miR-302b inhibitor, and miR-302b NC into MM1.S and RPMI8226 MM cells to detect the correlation between miR-302b expression in the pathological specimens and the clinicopathological features by qPCR, the target correlation between miR-302b and DKK1 by immunohistochemistry, qPCR and Western blot, and the correlation between miR-302b and the Wnt/β-catenin signaling pathway by Western blot. The effect of miR-302b on osteoblastogenesis was also studied in a subperiosteal tumorigenesis model of NOD/SCID nude mice.

RESULTS

We found that increased miR-302b suppressed cell proliferation and induced cell apoptosis in RPMI 8226 and MM1.S cells. TargetScan online bioinformatic analysis predicted that miR-302b is able to bind to 3'UTR of DKK1 mRNA. Target binding of miR-302b to DKK1 was demonstrated by dual-luciferase reporter assay, qPCR, Western blot and immunohistochemistry, indicating that miR-302b is able to degrade DKK1 in RPMI 8226 and MM1.S cells. The model of co-culturing MM cells with preosteoblast MC3T3-E1 cells showed that miR-302b inhibits MM-induced suppression of osteoblast differentiation. Western blotting showed that miR-302b promotes the Wnt/β-catenin signaling pathway in MM cells. Micro-CT and immunohistochemistry results showed that miR-302b suppresses myeloma bone destruction in vivo.

CONCLUSION

miR-302b is able to target DKK1 and promote the Wnt/β-catenin signaling pathway in MM.

Extracellular vesicles (EVs): What we know of the mesmerizing roles of these tiny vesicles in hematological malignancies?

Cancer is a complex disease in which a bidirectional collaboration between malignant cells and surrounding microenvironment creates an appropriate platform which ultimately facilitates the progression of the disease. The discovery of extracellular vesicles (EVs) was a turning point in the modern era of cancer biology, as their importance in human malignancies has set the stage to widen research interest in the field of cell-to-cell communication. The implication in short- and long-distance interaction via horizontally transfer of cellular components, ranging from non-coding RNAs to functional proteins, as well as stimulating target cells receptors by the means of ligands anchored on their membrane endows these "tiny vesicles with giant impacts" with incredible potential to re-educate normal tissues, and thus, to re-shape the surrounding niche. In this review, we highlight the pathogenic roles of EVs in human cancers, with an extensive focus on the recent advances in hematological malignancies.

Endothelial dysfunction in patients with lymphoproliferative disorders and its changes in the course of polychemotherapy

The article is dedicated to contemporary views on the change of endothelial function in the patients with lymphoproliferative disorders prior to, and in the process of, chemotherapeutic treatment. Considering that possibilities of standard examination do not always help identifying subclinical endothelial dysfunction, it is necessary to use specific methods, in particular, to determine the levels of endothelin-1 and vascular endothelial growth factor to monitor endothelial function. The objective of this review is to identify problems and prospects for recognizing early subclinical changes of endothelial function in the patients with lymphoproliferative disorders before and after chemotherapy. Assessing presence and severity of endothelial dysfunction may be useful for determining subclinical stages of cardiovascular damage, stratifying the risk of the patients with confirmed cardiovascular disease, and reducing the likelihood of cardio- and endotheliotoxic effects in patients long after chemotherapy. That is why early detection and immediate therapy of cardiovascular toxicity is currently the most important task in the patients with lymphoproliferative disorders, receiving chemotherapy.

Interleukin-8 blockade prevents activated endothelial cell mediated proliferation and chemoresistance of acute myeloid leukemia

One of the greatest challenges in treating acute myeloid leukemia (AML) is chemotherapy refractory disease. Previously, we demonstrated a novel mechanism whereby AML-induced endothelial cell (EC) activation leads to subsequent leukemia cell adherence, quiescence and chemoresistance, identifying activated ECs as potential mediators of relapse. We now show mechanistically that EC activation induces the secretion of interleukin-8 (IL-8) leading to significant expansion of non-adherent AML cells and resistance to cytarabine (Ara-C). Through crystallography and computational modeling, we identified a pocket within IL-8 responsible for receptor binding, screened for small molecules that fit within this pocket, and blocked IL-8 induced proliferation and chemo-protection of AML cells with a hit compound. Results from this study show a new therapeutic strategy for targeting the sanctuary of an activated leukemia microenvironment.

Immunogenicity moderation effect of interleukin-24 on myelogenous leukemia cells

Previous studies have shown that interleukin-24 (IL-24) has tumor-suppressing activity by multiple pathways. However, the immunogenicity moderation effect of IL-24 on malignant cells has not been explored extensively. In this study, we investigated the role of IL-24 in immunogenicity modulation of the myelogenous leukemia cells. Data show that myelogenous leukemia cells express low levels of immunogenicity molecules. Treatment with IL-24 could enhance leukemia cell immunogenicity, predominantly regulate leukemia cells to produce immune-associated cytokines, and improve the cytotoxic sensitivity of these cells to immune effector cells. IL-24 expression could retard transplanted leukemia cell tumor growth in vivo in athymic nude mice. Moreover, IL-24 had marked effects on downregulating the expression of angiogenesis-related proteins vascular endothelial growth factor, cluster of differentiation (CD) 31, CD34, collagen IV and metastasis-related factors CD147, membrane type-1 matrix metalloproteinase (MMP), and MMP-2 and MMP-9 in transplanted tumors. These findings indicated novel functions of this antitumor gene and characterized IL-24 as a promising agent for further clinical trial for hematologic malignancy immunotherapy.

Three-Dimensional Arrangement of Human Bone Marrow Microvessels Revealed by Immunohistology in Undecalcified Sections

The arrangement of microvessels in human bone marrow is so far unknown. We combined monoclonal antibodies against CD34 and against CD141 to visualise all microvessel endothelia in 21 serial sections of about 1 cm² size derived from a human iliac crest. The specimen was not decalcified and embedded in Technovit^® 9100. In different regions of interest, the microvasculature was reconstructed in three dimensions using automatic methods. The three-dimensional models were subject to a rigid semiautomatic and manual quality control. In iliac crest bone marrow, the adipose tissue harbours irregularly distributed haematopoietic areas. These are fed by networks of large sinuses, which are loosely connected to networks of small capillaries prevailing in areas of pure adipose tissue. Our findings are compatible with the hypothesis that capillaries and sinuses in human iliac crest bone marrow are partially arranged in parallel.

In Vitro and In Vivo Effects of Tumor Suppressor Gene PTEN on Endometriosis: An Experimental Study

BACKGROUND Endometriosis can cause dysmenorrhea and infertility. Its pathogenesis has not yet been clarified and its treatment continues to pose enormous challenges. The protein tyrosine phosphatase (PTEN) gene is a tumor suppressor gene. The aim of this study was to investigate the role and significance of PTEN protein in the occurrence, development, and treatment of endometriosis through changes in apoptosis rate, cell cycle, and angiogenesis. MATERIAL AND METHODS PTEN was overexpressed and silenced in lentiviral vectors and inserted into primary endometrial cells. The changes in cell cycle and apoptosis in the different PTEN expression groups were evaluated using flow cytometry. Vessel growth mimicry was observed using 3-dimensional culture. A human-mouse chimeric endometriosis model was constructed using SCID mice. Hematoxylin and eosin staining and immunohistochemistry were used to detect pathological changes in ectopic endometrial tissues and the expression of VEGF protein in a human-mouse chimeric endometriosis mouse model. RESULTS PTEN overexpression significantly increased apoptosis and inhibited the cell cycle compared with the silenced and control groups. Furthermore, cells expressing low PTEN levels were better able to undergo vasculogenic mimicry, and exhibited significantly increased angiogenesis compared to cells overexpressing PTEN. We found that ectopic foci were more easily formed in the endometrial tissue of SCID mice with low PTEN expression, and the VEGF expression in this group was relatively high. CONCLUSIONS PTEN inhibits the occurrence and development of endometriosis by regulating angiogenesis and the apoptosis and cell cycle of endometrial cells; therefore, we propose that the PTEN gene can be used to treat endometriosis.

Maintenance chemotherapy in children with ALL exerts metronomic-like thrombospondin-1 associated anti-endothelial effect

Maintenance chemotherapy is an important part of the treatment of ALL in children. It relies on the long-term oral administration of daily low-dose mercaptopurin and weekly low-dose methotrexate. Although it has been used in the clinic for decades, its mechanisms of action remain unclear. Here, we investigated different angiogenic and immune biomarkers to gain insights into the mechanisms of action of maintenance therapy in children with ALL. We thus monitored circulating endothelial cells (CEC), endothelial progenitor cells (EPC) and endothelial microparticles (EMP), pro-angiogenic factors (VEGF, VEGFR-1 and Ang-2), anti-angiogenic factor thrombospondin-1 (THBS1) and regulatory T lymphocytes (Treg) in 47 children with ALL during the maintenance phase of their treatment (at treatment initiation and after 6, 12 and 18 months). We observed a statistically significant decrease in EPC and EMP counts throughout the maintenance phase associated with a significant increase in THBS1 levels. No significant change was detected in other angiogenic markers or in Treg numbers.

The results presented here indicate that maintenance therapy in children with ALL exerts its antitumor activity at least in part through anti-angiogenic effects, similar to those induced by metronomic chemotherapy. Larger studies are now warranted to validate these findings and determine their clinical implications.

TGF-α and IL-6 plasma levels selectively identify CML patients who fail to achieve an early molecular response or progress in the first year of therapy

Early molecular response (EMR, BCR-ABL1 (IS)⩽10% at 3 months) is a strong predictor of outcome in imatinib-treated chronic phase chronic myeloid leukemia (CP-CML) patients, but for patients who transform early, 3 months may be too late for effective therapeutic intervention. Here, we employed multiplex cytokine profiling of plasma samples to test newly diagnosed CP-CML patients who subsequently received imatinib treatment. A wide range of pro-inflammatory and angiogenesis-promoting cytokines, chemokines and growth factors were elevated in the plasma of CML patients compared with that of healthy donors. Most of these normalized after tyrosine kinase inhibitor treatment while others remained high in remission samples. Importantly, we identified TGF-α and IL-6 as novel biomarkers with high diagnostic plasma levels strongly predictive of subsequent failure to achieve EMR and deep molecular response, as well as transformation to blast crisis and event-free survival. Interestingly, high TGF-α alone can also delineate a poor response group raising the possibility of a pathogenic role. This suggests that the incorporation of these simple measurements to the diagnostic work-up of CP-CML patients may enable therapy intensity to be individualized early according to the cytokine-risk profile of the patient.

Interleukin-8: A potent promoter of angiogenesis in gastric cancer

Angiogenesis is a critical process in the development of tumor malignancy and occurs at various stages of tumor progression. Interleukin-8 (IL-8) is a pro-angiogenic factor produced by tumor-infiltrating macrophages that has been revealed to facilitate the development of angiogenesis in various cancers. However, whether IL-8 activates angiogenesis in gastric cancer remains unclear. The present study investigated the effect of IL-8 on the migration and canalization capacities of human umbilical vein endothelial cells (HUVECs). In addition, the protein and messenger RNA (mRNA) expression of selected angiogenesis markers, consisting of vascular endothelial growth factor (VEGF)-A, VEGF receptor (VEGFR)-1 and VEGFR-2, were assessed in the HUVECs. The HUVECs were co-cultured with human gastric cancer SGC7901 cells and exposed to various concentrations of IL-8 (0, 0.2, 0.5, 0.8 and 1.0 ng/ml). The migration and canalization abilities of the cells were detected by Transwell chamber and tube formation assays. Protein expression was detected using immunofluorescence and western blot analysis, and mRNA levels were assessed using reverse transcription quantitative polymerase chain reaction. The protein and mRNA levels of VEGF-A, VEGFR-1 and VEGFR-2 were measured in HUVECs cultured for 24 h. IL-8 at concentrations of 0.5, 0.8 and 1.0 ng/ml significantly promoted HUVEC cell migration (P=0.005, P=0.001 and P<0.001, respectively) and tube formation (P=0.039, P=0.003 and P<0.001, respectively). IL-8 at concentrations of 0.2, 0.5, 0.8 and 1.0 ng/ml significantly elevated the protein levels of VEGF-A (P<0.001) and VEGFR-2 (P=0.034, P<0.001, P<0.001 and P<0.001, respectively). IL-8 at concentrations of 0.8 and 1.0 ng/ml significantly elevated the protein levels of VEGF-1 (P=0.037 and P=0.002, respectively). Similarly, IL-8 at concentrations of 0.5, 0.8 and 1.0 ng/ml significantly upregulated the mRNA levels of VEGF-A (P=0.046, P=0.001 and P<0.001, respectively) and VEGFR-1 (P=0.042, P<0.001 and P<0.001, respectively). IL-8 at concentrations of 0.2, 0.5, 0.8 and 1.0 ng/ml significantly upregulated the mRNA levels of VEGFR-2 (P=0.003, P=0.005, P<0.001 and P<0.001, respectively). In conclusion, IL-8 may be a potent promoter of angiogenesis in gastric cancer.

High coagulation factor VIII and von Willebrand factor in patients with lymphoma and leukemia

The risk of venous thromboembolism is increased in patients with lymphoma and leukemia; however, little is known about the potential underlying hereditary or acquired thrombophilia. We prospectively analyzed procoagulant markers and gene mutations in patients with lymphoma (n = 35) and leukemia (n = 10) at diagnosis and over the course of treatment. Global coagulation tests were normal in all patients, as were antithrombin and protein S. Activated protein C resistance caused by the factor V Leiden mutation was found in four patients, one patient had the G20210A mutation of the prothrombin gene, and one patient had protein C deficiency. The most striking findings were sustained very high levels of factor VIII (>150 %) in 30 patients (68 %), which correlated with high von Willebrand factor. An acute phase response in these patients was ruled out by absence of fever and normal IL-6 and -α. Elevated factor VIII is an independent thrombophilic risk factor and may play an etiologic role in thromboembolic complications in patients with malignant lymphoma. Since high von Willebrand factor is most likely caused by endothelial cell injury, an additional, unknown pathophysiological association with malignant lymphoma and acute leukemia is possible.

Role of Extracellular Vesicles in Hematological Malignancies

In recent years the role of tumor microenvironment in the progression of hematological malignancies has been widely recognized. Recent studies have focused on how cancer cells communicate within the microenvironment. Among several factors (cytokines, growth factors, and ECM molecules), a key role has been attributed to extracellular vesicles (EV), released from different cell types. EV (microvesicles and exosomes) may affect stroma remodeling, host cell functions, and tumor angiogenesis by inducing gene expression modulation in target cells, thus promoting cancer progression and metastasis. Microvesicles and exosomes can be recovered from the blood and other body fluids of cancer patients and contain and deliver genetic and proteomic contents that reflect the cell of origin, thus constituting a source of new predictive biomarkers involved in cancer development and serving as possible targets for therapies. Moreover, due to their specific cell-tropism and bioavailability, EV can be considered natural vehicles suitable for drug delivery. Here we will discuss the recent advances in the field of EV as actors in hematological cancer progression, pointing out the role of these vesicles in the tumor-host interplay and in their use as biomarkers for hematological malignancies.

Bone marrow vascular endothelial growth factor level per platelet count might be a significant predictor for the treatment outcomes of patients with diffuse large B-cell lymphomas

OBJECTIVE

Developing a parameter to predict bone marrow invasion by non-Hodgkin's lymphoma is an important unmet medical need for treatment decisions. This study aimed to confirm the validity of the hypothesis that bone marrow plasma vascular endothelial growth factor level might be correlated with the risk of bone marrow involvement and the prognosis of patients with diffuse large B-cell non-Hodgkin's lymphoma.

METHODS

Forty-nine diffuse large B-cell lymphoma patients treated with rituximab, cyclophosphamide, daunorubicin, vincristine and prednisolone regimen were enrolled. Vascular endothelial growth factor level was measured with enzyme-linked immunosorbent assay. The validity of bone marrow plasma vascular endothelial growth factor level and bone marrow vascular endothelial growth factor level per platelet count for predicting treatment response and survival after initial rituximab, cyclophosphamide, daunorubicin, vincristine and prednisolone combined chemotherapy was assessed.

RESULTS

Bone marrow plasma vascular endothelial growth factor level per platelet count was significantly associated with old age (≥ 65 years), poor performance score (≥ 2), high International prognosis index (≥ 3) and bone marrow invasion. The patients with high bone marrow plasma vascular endothelial growth factor level per platelet count (≥ 3.01) showed a significantly lower complete response rate than the others. On Kaplan-Meier survival curves, the patients with high bone marrow plasma vascular endothelial growth factor levels (≥ 655 pg/ml) or high bone marrow plasma vascular endothelial growth factor level per platelet count (≥ 3.01) demonstrated a significantly shorter overall survival and progression-free survival than the others. In the patients without bone marrow involvement, bone marrow plasma vascular endothelial growth factor level per platelet count had a significant relationship with overall survival and progression-free survival. Multivariate analysis revealed that the patients without BM invasion showing high level of bone marrow plasma vascular endothelial growth factor per platelet count had significantly shorter progression-free survival and overall survival.

CONCLUSIONS

Bone marrow plasma vascular endothelial growth factor level per platelet count might be associated with bone marrow invasion by diffuse large B-cell lymphoma and is correlated with clinical outcomes after treatment.

Isoindolone derivative QSN-10c induces leukemic cell apoptosis and suppresses angiogenesis via PI3K/AKT signaling pathway inhibition

AIM

2-(4,6-Dimethoxy-1,3-dioxoisoindolin-2-yl) ethyl 2-chloroacetate (QSN-10c) is one of isoindolone derivatives with antiproliferative activity against human umbilical vein endothelial cells (HUVECs). The aim of this study was to investigate its antitumor activity in vitro and anti-angiogenic effects in vitro and in vivo.

METHODS

K562 leukemic cells and HUVECs were used for in vitro studies. Cell viability was examined using MTT assay. Cell apoptosis and mitochondrial transmembrane potential (Δψm) were detected with flow cytometry. Tube formation and migration of HUVECs were studied using two-dimensional Matrigel assay and wound-healing migration assay, respectively. VEGF levels were analyzed with RT-PCR and Western blotting. A zebrafish embryo model was used for in vivo anti-angiogenic studies. The molecular mechanisms for apoptosis in K562 cells and antiangiogenesis were measured with Western blotting.

RESULTS

In antitumor activity studies, QSN-10c suppressed the viability of K562 cells and induced apoptosis in dose- and time-dependent manners. Furthermore, QSN-10c dose-dependently decreased the Δψm in K562 cells, increased the release of cytochrome c and the level of Bax, and decreased the level of Bcl-2, suggesting that QSN-10c-induced apoptosis of K562 cells was mediated via the mitochondrial apoptotic pathway. In anti-angiogenic activity studies, QSN-10c suppressed the viability of HUVECs and induced apoptosis in dose dependent manners. QSN-10c treatment did not alter the Δψm in HUVECs, but dose-dependently inhibited the expression of VEGF, inhibited the tube formation and cell migration in vitro, and significantly suppressed the number of ISVs in zebrafish embryos in vivo. Furthermore, QSN-10c dose-dependently suppressed the phosphorylation of AKT and GSK3β in both HUVECs and K562 cells.

CONCLUSION

QSN-10c is a novel antitumor compound that exerts both antitumor and anti-angiogenic effects via inhibiting the PI3K/AKT/GSK3β signaling pathway.

Exosome-mediated crosstalk between chronic myelogenous leukemia cells and human bone marrow stromal cells triggers an interleukin 8-dependent survival of leukemia cells

Chronic myelogenous leukemia (CML) is a myeloproliferative disorder characterized by the Bcr-Abl oncoprotein with constitutive tyrosine kinase activity. Exosomes are nanovesicles released by cancer cells that are involved in cell-to-cell communication thus potentially affecting cancer progression. It is well known that bone marrow stromal microenvironment contributes to disease progression through the establishment of a bi-directional crosstalk with cancer cells. Our hypothesis is that exosomes could have a functional role in this crosstalk. Interleukin-8 (IL 8) is a proinflammatory chemokine that activates multiple signalling pathways downstream of two receptors (CXCR1 and CXCR2). We demonstrated that exosomes released from CML cells stimulate bone marrow stromal cells to produce IL 8 that, in turn, is able to modulate both in vitro and in vivo the leukemia cell malignant phenotype.

Detection of an activated JAK3 variant and a Xq26.3 microdeletion causing loss of PHF6 and miR-424 expression in myelodysplastic syndromes by combined targeted next generation sequencing and SNP array analysis

Myelodysplastic syndromes (MDS) are hematopoietic disorders characterized by ineffective hematopoiesis and progression to acute leukemia. In patients ineligible for hematopoietic stem cell transplantation, azacitidine is the only treatment shown to prolong survival. However, with the availability of a growing compendium of cancer biomarkers and related drugs, analysis of relevant genetic alterations for individual MDS patients might become part of routine evaluation. Therefore and in order to cover the entire bone marrow microenvironment involved in the pathogenesis of MDS, SNP array analysis and targeted next generation sequencing (tNGS) for the mostly therapy relevant 46 onco- and tumor-suppressor genes were performed on bone marrow biopsies from 29 MDS patients. In addition to the detection of mutations known to be associated with MDS in NRAS, KRAS, MPL, NPM1, IDH1, PTPN11, APC and MET, single nucleotide variants so far unrelated to MDS in STK11 (n=1), KDR (n=3), ATM (n=1) and JAK3 (n=2) were identified. Moreover, a recurrent microdeletion was detected in Xq26.3 (n=2), causing loss of PHF6 expression, a potential tumor suppressor gene, and the miR-424, which is involved in the development of acute myeloid leukemia. Finally, combined genetic aberrations affecting the VEGF/VEGFR pathway were found in the majority of cases demonstrating the diversity of mutations affecting different nodes of a particular signaling network as an intrinsic feature in MDS patients. We conclude that combined SNP array analyses and tNGS can identify established and novel therapy relevant genomic aberrations in MDS patients and track them in a clinical setting for individual therapy selection.

Gene Expression of VEGF-A and VEGF-C in Peripheral Blood Mononuclear Cells of Iranian Patients with Acute Myeloid Leukemia

Objective: The crucial role of angiogenesis in the pathophysiology of acute myeloid leukemia (AML) has been proposed. One of the key regulators of angiogenesis is the vascular endothelial growth factor (VEGF). Among the VEGF family, it has been observed that VEGF-A and VEGF-C are expressed by AML cells and mediate leukemic cell proliferation, survival, and resistance to chemotherapy. Emerging evidence, however, suggests that elevated levels of VEGF or a proangiogenic phenotype may impede, rather than promote, early tumor development and progression. As the significance of VEGF-A and VEGF-C levels in the pathogenesis of AML has not been clarified well, the aim of this study is to evaluate gene expression of these angiogenesis promoters and its possible prognostic value in peripheral blood mononuclear cells of Iranian patients with AML.

Materials and Methods: We investigated the mRNA expression of VEGF-A and VEGF-C in peripheral blood mononuclear cells of 27 patients with newly diagnosed AML and 28 healthy controls by quantitative real-time PCR.

Results: Expression of VEGF-C mRNA was significantly lower in AML patients than in healthy controls (p<0.001). However, there was no significant decrement in expression of VEGF-A mRNA of AML patients compared to the control group (p=0.861). VEGF-A and VEGF-C expression were not able to predict clinical outcome.

Conclusion: Our data showed that AML is associated with a decreased expression of VEGF-C mRNA. However, expression levels did not influence the clinical outcome in our study. It seems that angiogenesis is affected by different cytokines other than VEGF-C or VEGF-A, and VEGF is also affected by different cytokines. Taken together, these findings help to provide new insights into the investigation of other angiogenic factors and cytokines that may play roles in the pathogenesis of AML.

Conflict of interest:None declared.

The possible diagnostic and prognostic use of systemic chemokine profiles in clinical medicine—the experience in acute myeloid leukemia from disease development and diagnosis via conventional chemotherapy to allogeneic stem cell transplantation

Chemokines are important regulators of many different biological processes, including (i) inflammation with activation and local recruitment of immunocompetent cells; (ii) angiogenesis as a part of inflammation or carcinogenesis; and (iii) as a bridge between the coagulation system and inflammation/immune activation. The systemic levels of various chemokines may therefore reflect local disease processes, and such variations may thereby be used in the routine clinical handling of patients. The experience from patients with myeloproliferative diseases, and especially patients with acute myeloid leukemia (AML), suggests that systemic plasma/serum cytokine profiles can be useful, both as a diagnostic tool and for prognostication of patients. However, cytokines/chemokines are released by a wide range of cells and are involved in a wide range of biological processes; the altered levels may therefore mainly reflect the strength and nature of the biological processes, and the optimal clinical use of chemokine/cytokine analyses may therefore require combination with organ-specific biomarkers. Chemokine levels are also altered by clinical procedures, therapeutic interventions and the general status of the patients. A careful standardization of sample collection is therefore important, and the interpretation of the observations will require that the overall clinical context is considered. Despite these limitations, we conclude that analysis of systemic chemokine/cytokine profiles can reflect important clinical characteristics and, therefore, is an important scientific tool that can be used as a part of future clinical studies to identify clinically relevant biomarkers.

Hypoxia-inducible factor (HIF)-1α suppression in myeloma cells blocks tumoral growth in vivo inhibiting angiogenesis and bone destruction

Hypoxia-inducible transcription factor-1 (HIF-1α) is overexpressed in multiple myeloma (MM) cells within the hypoxic microenvironment. Herein, we explored the effect of persistent HIF-1α inhibition by a lentivirus short hairpin RNA pool on MM cell growth either in vitro or in vivo and on the transcriptional and pro-angiogenic profiles of MM cells. HIF-1α suppression did not have a significant impact on MM cell proliferation and survival in vitro although, increased the antiproliferative effect of lenalidomide. On the other hand, we found that HIF-1α inhibition in MM cells downregulates the pro-angiogenic genes VEGF, IL8, IL10, CCL2, CCL5 and MMP9. Pro-osteoclastogenic cytokines were also inhibited, such as IL-7 and CCL3/MIP-1α. The effect of HIF-1α inhibition was assessed in vivo in nonobese diabetic/severe combined immunodeficiency mice both in a subcutaneous and an intratibial MM model. HIF-1α inhibition caused a dramatic reduction in the weight and volume of the tumor burden in both mouse models. Moreover, a significant reduction of the number of vessels and vascular endothelial growth factors (VEGFs) immunostaining was observed. Finally, in the intratibial experiments, HIF-1α inhibition significantly blocked bone destruction. Overall, our data indicate that HIF-1α suppression in MM cells significantly blocks MM-induced angiogenesis and reduces MM tumor burden and bone destruction in vivo, supporting HIF-1α as a potential therapeutic target in MM.

Quantification of plasma and bone marrow VEGF and angiopoietin-2 levels in pediatric malignancies

INTRODUCTION

Data on angiogenesis in pediatric patients with malignancy are scarce. Our aim was to study angiogenic growth factors vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang2) in pediatric oncological patients at diagnosis and a few months after the beginning of the therapy.

PATIENTS AND METHODS

Eighty-four consecutive patients with malignancy were included in this study. The levels of plasma and bone marrow VEGF and Ang2 were analyzed by enzyme-linked immunosorbent assay.

RESULTS

The levels of VEGF were higher in patients with solid tumors than in patients with leukemias (P=0.003), whereas Ang2 concentrations showed the opposite (P=0.003). Interestingly, the plasma concentrations of both VEGF and Ang2 correlated with concentrations in the bone marrow (P<0.05). Leukemia patients with lower VEGF level and patients with higher Ang2 level at follow-up had longer event-free survival than other patients (P=0.032 and 0.053, respectively).

DISCUSSION

The results of our study enlighten the behavior of 2 different angiogenic factors in pediatric patients with malignancy. An interesting finding was the connection between survival of pediatric leukemia patients and angiogenic factor levels a few months after the beginning of therapy. Pathophysiology and clinical applications of these findings need further studies.

Interrelationship and expression profiling of cyclooxygenase and angiogenic factors in Indian patients with multiple myeloma

Multiple myeloma (MM) is classically illustrated by a desynchronized cytokine system with rise in inflammatory cytokines. There are recent reports which emphasized the potential role of angiogenesis in the development of MM. Role of cyclooxygenase 2 (COX-2) is well documented in the pathogenesis of solid tumors, but little is known about its occurrence and function in hematologic neoplasms. Involvement of neoangiogenesis is reported in the progression of MM, and angiopoietins probably contribute to this progression by enhancing neovascularization. Circulatory and mRNA levels of angiogenic factors and cyclooxygenase were determined in 125 subjects (75 MM patients and 50 healthy controls) by using enzyme-linked immunosorbent assay and quantitative PCR. We observed significant increase for angiogenic factors (Ang-1, Ang-2, hepatocyte growth factor, and vascular endothelial growth factor) and cyclooxygenase at circulatory level, as well as at mRNA level, as compared to healthy controls except insignificant increase for Ang-1 at circulatory level. We have also observed the significant positive correlation of all angiogenic factors with cyclooxygenase. The strong association found between angiogenic factors and COX-2 in this study may lead to the development of combination therapeutic strategy to treat MM. Therefore, targeting COX-2 by using its effective inhibitors demonstrating antiangiogenic and antitumor effects could be used as a new therapeutic approach for treatment of MM.

Carboxyamidotriazole-orotate inhibits the growth of imatinib-resistant chronic myeloid leukaemia cells and modulates exosomes-stimulated angiogenesis

The Bcr/Abl kinase has been targeted for the treatment of chronic myelogenous leukaemia (CML) by imatinib mesylate. While imatinib has been extremely effective for chronic phase CML, blast crisis CML are often resistant. New therapeutic options are therefore needed for this fatal disease. Although more common in solid tumors, increased microvessel density was also reported in chronic myelogenous leukaemia and was associated with a significant increase of angiogenic factors, suggesting that vascularity in hematologic malignancies is a controlled process and may play a role in the leukaemogenic process thus representing an alternative therapeutic target. Carboxyamidotriazole-orotate (CTO) is the orotate salt form of carboxyamidotriazole (CAI), an orally bioavailable signal transduction inhibitor that in vitro has been shown to possess antileukaemic activities. CTO, which has a reduced toxicity, increased oral bioavailability and stronger efficacy when compared to the parental compound, was tested in this study for its ability to affect imatinib-resistant CML tumor growth in a xenograft model. The active cross talk between endothelial cells and leukemic cells in the bone marrow involving exosomes plays an important role in modulating the process of neovascularization in CML. We have thus investigated the effects of CTO on exosome-stimulated angiogenesis. Our results indicate that CTO may be effective in targeting both cancer cell growth and the tumor microenvironment, thus suggesting a potential therapeutic utility for CTO in leukaemia patients.

Angiogenesis: A Target in Solid Tumors, Also in Leukemia?

Targeting angiogenesis has become an established therapeutic approach to fighting solid tumor growth in cancer patients. Even though increased angiogenesis has long been recognized in various types of hematologic malignancies, the molecular basis underlying this angiogenic switch in leukemias remains poorly understood. The BM stroma is gaining increasing attention for its role in promoting leukemia growth and resistance against current treatments with tyrosine kinase inhibitors. This article provides a brief overview of the role of angiogenesis in leukemias, discusses recent insights into the role of placenta growth factor (PlGF), a VEGF family member, as a novel disease candidate in chronic myeloid leukemia (CML), and highlights the therapeutic potential of PlGF blockade for imatinib-resistant CML.

The relationship between tissue factor and cancer progression: insights from bench and bedside

It is now widely recognized that a strong correlation exists between cancer and aberrant hemostasis. Patients with various types of cancers, including pancreatic, colorectal, and gastric cancer, often develop thrombosis, a phenomenon commonly referred to as Trousseau syndrome. Reciprocally, components from the coagulation cascade also influence cancer progression. The primary initiator of coagulation, the transmembrane receptor tissue factor (TF), has gained considerable attention as a determinant of tumor progression. On complex formation with its ligand, coagulation factor VIIa, TF influences protease-activated receptor-dependent tumor cell behavior, and regulates integrin function, which facilitate tumor angiogenesis both in vitro and in mouse models. Furthermore, evidence exists that an alternatively spliced isoform of TF also affects tumor growth and tumor angiogenesis. In patient material, TF expression and TF cytoplasmic domain phosphorylation correlate with disease outcome in many, but not in all, cancer subtypes, suggesting that TF-dependent signal transduction events are a potential target for therapeutic intervention in selected types of cancer. In this review, we summarize our current understanding of the role of TF in tumor growth and metastasis, and speculate on anticancer therapy by targeting TF.

Oxygen tension plays a critical role in the hematopoietic microenvironment in vitro

BACKGROUND

In the bone marrow mesenchymal stromal cells and osteoblasts form functional niches for hematopoietic stem and progenitor cells. This microenvironment can be partially mimicked using in vitro co-culture systems. In this study, we examined the oxygen tension in three distinct compartments in a co-culture system of purified CD34(+) cells and mesenchymal stromal cells with regard to different spatial localizations.

DESIGN AND METHODS

Hypoxic cells in the co-culture were visualized by pimonidazole staining. Hematopoietic cell distribution, and functional and phenotypic characteristics were analyzed by flow cytometry. The secretion of vascular endothelial growth factor and stromal-derived factor-1 by mesenchymal stromal cells in low oxygen co-cultures was determined by an enzyme-linked immunosorbent assay. The effect of co-culture medium on the hematopoietic cell migration potential was tested in a transwell assay.

RESULTS

In co-cultures under atmospheric oxygen tension, regions of low oxygen tension could be detected beneath the feeder layer in which a reservoir of phenotypically more primitive hematopoietic cells is located in vitro. In low oxygen co-culture, the adhesion of hematopoietic cells to the feeder layer was decreased, whereas hematopoietic cell transmigration beneath mesenchymal stromal cells was favored. Increased vascular endothelial growth factor-A secretion by mesenchymal stromal cells under low oxygen conditions, which increased the permeability of the monolayer, was responsible for this effect. Furthermore, vascular endothelial growth factor-A expression in low oxygen mesenchymal stromal cells was induced via hypoxia-inducible factor signaling. However, stromal cell-derived factor-1 secretion by mesenchymal stromal cells was down-regulated under low oxygen conditions in a hypoxia-inducible factor-independent manner.

CONCLUSIONS

We demonstrate for the first time that differences in oxygen tension cause selective modification of hematopoietic cell and mesenchymal stromal cell interactions in a co-culture system, thus confirming that oxygen tension plays a critical role in the interaction between hematopoietic cells and the niche environment.

Monitoring serum levels ELR+ CXC chemokines and the relationship between microvessel density and angiogenic growth factors in multiple myeloma

BACKGROUND

The ELR+ CXC chemokines are important mediators of tumorigenesis, related to their angiogenic properties. Angiogenesis appears to be a prominent feature in the progression of multiple myeloma (MM). CXC chemokines have four highly conserved cysteine amino acid residues, with the first two cysteine molecules separated by a single amino acid. The angiogenic potential of this group is determined by the presence of three amino acid residues (Glu-Leu-Arg: the ELR motif) preceding the first cysteine amino acid, in the NH2 terminus.

AIMS

The purpose of this study was to determine serum concentrations of angiogenesis-related chemokines ELR+ motif, such as interleukin-8 (IL-8), epithelial neutrophil activating protein-78 (ENA-78) and growth-related gene alpha (GRO-α), as well the bone marrow microvascular density (MVD) in patients with MM at diagnosis and after treatment, in plateau phase. We also evaluated the relationship among them with other known growth factors involved in angiogenesis.

METHODS

Serum levels of the ELR+ CXC chemokines: IL-8, ENA-78 and GRO-α as well as of the angiogenic factors: hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and tumor necrosis factor-α (TNF-α) were determined in 63 newly diagnosed MM patients, in 30 in plateau phase and in 20 healthy controls. Serum measurements of them were performed with commercially available kits for ELISA. Bone marrow biopsies were performed before and after treatment, in plateau phase, in order to determine MVD by staining vessels with anti-CD31.

RESULTS

Serum concentrations of IL-8, ENA-78, GRO-α and TNF-α were significantly higher in the group of MM patients (44.5±25.3, 765±572.1, 186.5±129.1 and 4.2±2.8 pg/ml, respectively) in comparison to control group (27.3±6.4, 335.1±268.6, 112.5±76.1 and 1.3±0.8 pg/ml) (p<0.02 for GRO-α, p<0.001 for other cases). We also found that untreated patients had higher levels of IL-8, ENA-78, GRO-α than post treatment patients, but statistical significant difference was found only for IL-8 (48.36±30.93 pg/ml vs. 35.05±19.77 pg/ml, p<0.001). Furthermore IL-8, GRO-α, TNF-α, HGF and VEGF were significantly higher with increasing disease stage (p<0.001 in all cases). ENA-78 serum levels were higher in stage III than in stage I and II, but without statistical significance. Additionally we correlated each proinflammatory cytokine with well known angiogenic factors such as HGF, VEGF and TNF-α. A positive correlation was found between serum HGF and IL-8 and GRO-α (r=0.316 p<0.01, r=0.297 p<0.02, respectively). Similarly serum VEGF correlated with ENA-78 and GRO-α (r=0.323 p<0.01, r=0.469 p<0.001, respectively). In the pretreatment group of patients a positive correlation between bone marrow MVD and serum levels of GRO-α was found (r=0.304 p<0.01). There was a difference in survival times between patients with higher than median versus low IL-8, ENA-78 and GRO-α levels, but the differences could not reach statistical significance in either case.

CONCLUSIONS

These findings support the hypothesis that ELR+ motif CXC chemokines, such as IL-8, ENA-78 and GRO-α correlate with angiogenic growth factors and may play a role in the progression of MM. Further studies are needed to determine their prognostic and predictive significance.

Role of exosomes released by chronic myelogenous leukemia cells in angiogenesis

Our study is designed to assess if exosomes released from chronic myelogenous leukemia (CML) cells may modulate angiogenesis. We have isolated and characterized the exosomes generated from LAMA84 CML cells and demonstrated that addition of exosomes to human vascular endothelial cells (HUVEC) induces an increase of both ICAM-1 and VCAM-1 cell adhesion molecules and interleukin-8 expression. The stimulation of cell-cell adhesion molecules was paralleled by a dose-dependent increase of adhesion of CML cells to a HUVEC monolayer. We further showed that the treatment with exosomes from CML cells caused an increase in endothelial cell motility accompanied by a loss of VE-cadherin and β-catenin from the endothelial cell surface. Functional characterization of exosomes isolated from CML patients confirmed the data obtained with exosomes derived from CML cell line. CML exosomes caused reorganization into tubes of HUVEC cells cultured on Matrigel. When added to Matrigel plugs in vivo, exosomes induced ingrowth of murine endothelial cells and vascularization of the Matrigel plugs. Our results suggest for the first time that exosomes released from CML cells directly affect endothelial cells modulating the process of neovascularization.

The bone marrow stroma in hematological neoplasms--a guilty bystander

In the setting of hematological neoplasms, changes in the bone marrow (BM) stroma might arise from pressure exerted by the neoplastic clone in shaping a supportive microenvironment, or from chronic perturbation of the BM homeostasis. Under such conditions, alterations in the composition of the BM stroma can be profound, and could emerge as relevant prognostic factors. In this Review, we delineate the multifaceted contribution of the BM stroma to the pathobiology of several hematological neoplasms, and discuss the impact of stromal modifications on the natural course of these diseases. Specifically, we highlight the involvement of BM stromal components in lymphoid and myeloid malignancies, and present the most relevant processes responsible for remodeling the BM stroma. The role of bystander BM stromal elements in the setting of hematological neoplasms is discussed, strengthening the rationale for treatment strategies that target the BM stroma.

Angiopoietin-2: a potential novel diagnostic marker in multiple myeloma

BACKGROUND

Multiple myeloma (MM) was the first hematological malignancy in which a prognostic relevance of bone marrow (BM) angiogenesis was reported. Microenvironment formed by reactive oxygen species, growth factors and chemokines initiates the process of BM angiogenesis. Among the angiopoietins, angiopoietin-1 is involved in vessel stability, whereas angiopoietin-2 is involved in vessel sprouting.

DESIGN AND METHODS

Circulatory levels of angiopoietin-1, angiopoietin-2 and VEGF in 62 MM patients and 50 healthy controls were determined using ELISA.

RESULTS

Significant increase in VEGF and angiopoietin-2 level was observed in patients which correlated positively with the severity of the disease, whereas no alteration was observed in angiopoietin-1 levels.

CONCLUSION

Significant elevation in angiopoietin-2 and VEGF levels and their correlation with severity of the disease indicate their utility as potential tumor markers along with β(2)- microglobulin and might also suggest new therapeutic target for anticancer treatment.

Circulating interleukin (IL)-8, IL-2R, IL-12, and IL-15 levels are independently prognostic in primary myelofibrosis: a comprehensive cytokine profiling study

PURPOSE

Abnormal cytokine expression accompanies myelofibrosis and might be a therapeutic target for Janus-associated kinase (JAK) inhibitor drugs. This study describes the spectrum of plasma cytokine abnormalities in primary myelofibrosis (PMF) and examines their phenotypic correlates and prognostic significance.

PATIENTS AND METHODS

Patients included in this study were required to have archived plasma, bone marrow biopsy, and cytogenetic information available at the time of first referral to the Mayo Clinic. Multiplex biometric sandwich immunoassay was used to measure plasma levels of 30 cytokines.

RESULTS

In total, 127 PMF patients were studied; comparison with normal controls (n = 35) revealed significantly increased interleukin-1β (IL-1β), IL-1RA, IL-2R, IL-6, IL-8, IL-10, IL-12, IL-13, IL-15, tumor necrosis factor α (TNF-α), granulocyte colony-stimulating factor (G-CSF), interferon alfa (IFN-α), macrophage inflammatory protein 1α (MIP-1α), MIP-1β, hepatocyte growth factor (HGF), IFN-γ-inducible protein 10 (IP-10), monokine induced by IFN-γ (MIG), monocyte chemotactic protein 1 (MCP-1), and vascular endothelial growth factor (VEGF) levels and decreased IFN-γ levels. In treatment-naive patients (n = 90), increased levels of IL-8 (P < .001), IL-2R (P < .001), IL-12 (P < .001), IL-15 (P = .001), and IP-10 (P = .003) were independently predictive of inferior survival. A similar multivariable analysis that included all 127 study patients confirmed the prognostic value of these five cytokines, and IL-8, IL-2R, IL-12, and IL-15 remained significant when risk stratification, according to the recently revised Dynamic International Prognostic Scoring System (DIPSS plus), was added to the multivariable model. Leukemia-free survival was predicted by IL-8, which was also the only cytokine associated with ≥ 1% circulating blasts. Other cytokine-phenotype associations included increased IL-8 and constitutional symptoms; IL-2R, IL-12, and transfusion need; IL-2R, IL-8, and leukocytosis; IP-10 and thrombocytopenia; HGF, MIG, IL-1RA, and marked splenomegaly; and IL-1RA, IL-2R, IP-10, MIP-1β, and JAK2V617F. A two-cytokine (IL-8/IL-2R) -based risk categorization delineated prognostically different groups within specific DIPSS plus risk categories.

CONCLUSION

This study signifies the presence of specific cytokine-phenotype associations in PMF and a prognostically relevant plasma cytokine signature that might prove useful as a laboratory tool for predicting and monitoring treatment response.

Disruption of Src function potentiates Chk1-inhibitor-induced apoptosis in human multiple myeloma cells in vitro and in vivo

Ras/MEK/ERK pathway activation represents an important compensatory response of human multiple myeloma (MM) cells to checkpoint kinase 1 (Chk1) inhibitors. To investigate the functional roles of Src in this event and potential therapeutic significance, interactions between Src and Chk1 inhibitors (eg, UCN-01 or Chk1i) were examined in vitro and in vivo. The dual Src/Abl inhibitors BMS354825 and SKI-606 blocked Chk1-inhibitor-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation, markedly increasing apoptosis in association with BimEL up-regulation, p34(cdc2) activation, and DNA damage in MM cell lines and primary CD138(+) MM samples. Loss-of-function Src mutants (K297R, K296R/Y528F) or shRNA knock-down of Src prevented the ERK1/2 activation induced by Chk1 inhibitors and increased apoptosis. Conversely, constitutively active Ras or mitogen-activated protein kinase/ERK kinase 1 (MEK1) significantly diminished the ability of Src inhibitors to potentiate Chk1-inhibitor lethality. Moreover, Src/Chk1-inhibitor cotreatment attenuated MM-cell production of vascular endothelial growth factor and other angiogenic factors (eg, ANG [angiogenin], TIMP1/2 [tissue inhibitor of metalloproteinases 1/2], and RANTES [regulated on activation normal T-cell expressed and secreted]), and inhibited in vitro angiogenesis. Finally, coadministration of BMS354825 and UCN-01 suppressed human MM tumor growth in a murine xenograft model, increased apoptosis, and diminished angiogenesis. These findings suggest that Src kinase is required for Chk1-inhibitor-mediated Ras → ERK1/2 signaling activation, and that disruption of this event sharply potentiates the anti-MM activity of Chk1 inhi-bitors in vitro and in vivo.

Assessment of bone marrow microvessel density in chronic lymphocytic leukemia

INTRODUCTION

Angiogenesis is a physiologic process of new blood vessels formation mediated by various cytokines called proangiogenic and antiangiogenic factors. Enhancement of angiogenesis in chronic lymphocytic leukemia (CLL) has been recognized more recently. Our study assesses CD34 and von Willebrand factor (vWf) expression and microvessel density (MVD) in the bone marrow of patients with CLL.

AIMS

(1) To assess bone marrow MVD in CLL using 2 different monoclonal antibodies, CD34 and vWf; and (2) To examine the possible association of marrow MVD and clinical course, pattern of marrow infiltration, Rai stage, CD38 positivity, and cytogenetic abnormalities detected by fluorescence in situ hybridization.

MATERIALS AND METHODS

Bone marrow specimens from 33 patients with CLL and 10 controls were studied. A single microvessel was defined as any vessel with a clear lumen. The screening of the slides was carried out by hotspot method. The slides were initially screened at low power to identify the areas with highest number of microvessel or vascularity hotspot. The count of microvessel in a sufficiently extended field (40x objective lens, 10x ocular lens) was then performed. The mean value of 10 most vascularized areas at 400x field was considered as MVD for a sample.

RESULTS

There was a significant difference between MVD counts according to the antibody used. MVD was higher using CD34 versus vWF (CD34: mean +/- SD, 35.91+/-15.7; 95% confidence interval of mean, 30.34-41.48 vessels/field versus vWF: 8.15+/-4.65; 95% confidence interval of mean, 4.11-12.44 vessels/field; P<0.0001]. Bone marrow MVD detected by CD34 was significantly higher in patients with CD38 expression more than 30% (P=0.006) and in patients with unfavorable cytogenetic abnormalities. However, no significant MVD differences were detected between CLL subgroups with regard to clinical course, pattern of marrow infiltration, and Rai stage. Bone marrow MVD in patients with CLL was significantly higher than that in controls (P<0.0001).

CONCLUSIONS

MVD assessment using anti-CD34 resulted in higher MVD counts than when using anti-vWF antibody. However, no MVD differences were detected between CLL subgroups subdivided according to the above-mentioned prognostic factors except CD38 expression and genetic abnormalities.

Does serum soluble vascular endothelial growth factor levels have different importance in pediatric acute leukemia and malignant lymphoma patients?

Vascular endothelial growth factor (VEGF) seems to play a central role in angiogenesis-lymphangiogenesis in hematological malignancies. There are limited data related to childhood hematologic malignancies. The aim of the study was to evaluate soluble VEGF (sVEGF) levels in children with acute leukemia and malignant lymphoma (ML) at diagnosis and in remission. The levels of serum sVEGF were measured by enzyme-linked immunosorbent assay (ELISA) in 20 children with acute leukemia, 33 children with different histopathological subtypes of ML, and 20 healthy controls. The levels of sVEGF at diagnosis (range 2 -1040 pg/mL; median 52 pg/mL) was significantly lower than in remission (range 136 -1960 pg/mL; median 630 pg/mL) in acute myeloid leukemia (AML) group (P = .018). The sVEGF levels at diagnosis (range: 2 -640 pg/mL; median 89 pg/mL) was significantly lower compared to remission values (range: 116 -1960 pg/mL; median 136 pg/mL) in patients with acute lymphoblastic leukemia (ALL) (P = .002). In ML group, including Burkitt's lymphoma (BL), T-cell non-Hodgkin's lymphoma (NHL), and Hodgkin's lymphoma (HL), sVEGF levels at diagnosis were higher than remission levels, but there was no statistically significant difference (P >.05). On the other hand, there were significant difference between levels in active disease and control group, ie, BL versus control, T-cell NHL versus control, and HL versus control (P = .008, P = .043, P = .007, respectively). The authors noticed that sVEGF levels showed distinct behavioral pattern in different childhood malignancies at diagnosis and in remission. In acute leukemia and ML patients, VEGF acts through different pathophysiological mechanisms, in both bone marrow (BM) angiogenesis and lymphoid tissue lymphangiogenesis.