Targeting autocrine and paracrine VEGF receptor pathways inhibits human lymphoma xenografts in vivo

Hierarchical-unlocking virus-esque NanoCRISPR precisely disrupts autocrine and paracrine pathway of VEGF for tumor inhibition and antiangiogenesis

Vascular endothelial growth factor (VEGF) not only serves as an autocrine survival factor for tumor cells themselves, but also stimulates angiogenesis by paracrine pathway. Strategies targeting VEGF holds tremendous potential for tumor therapy, however, agents targeting VEGF are limited by intolerable side effects, together with incomplete and temporary blocking of VEGF, resulting in unsatisfactory and unsustained therapeutic outcomes. Herein, hierarchical-unlocking virus-esque NanoCRISPR (HUNGER) is constructed for complete, permanent and efficient intracellular disruption of autocrine and paracrine pathway of VEGF, thereby eliciting notable tumor inhibition and antiangiogenesis. After intravenous administration, HUNGER exhibits prolonged blood circulation and hyaluronic acid-CD44 mediated tumor-targeting capability. Subsequently, when matrix metalloproteinase-2 is overexpressed in the tumor microenvironment, the PEG layer will be removed. The cell-penetrating peptide R8 endows HUNGER deep tumor penetration and specific cellular uptake. Upon cellular internalization, HUNGER undergoes hyaluronidase-triggered deshielding in lysosome, lysosomal escape is realized swiftly, and then the loaded CRISPR/Cas9 plasmid (>8 kb) is transported to nucleus efficiently. Consequentially, complete, permanent and efficient intracellular disruption of autocrine and paracrine pathway of VEGF ensures inhibition of angiogenesis and tumor growth with inappreciable toxicity. Overall, this work opens a brand-new avenue for anti-VEGF therapy and presents a feasible strategy for in vivo delivery of CRISPR/Cas9 system.

Evaluation of VEGF and VEGFR gene expression as prognostic markers in low and intermediate‑1 risk patients with myelodysplastic syndromes

Vascular endothelial growth factors (VEGFs) are angiogenic factors playing a key role in tumor development. VEGFs are produced by different normal and tumor cells, including platelets, lymphocytes and mononuclear cells of peripheral blood. VEGF (VEGF-A, VEGF-C and VEGF-D) and VEGFR (VEGFR1, VEGFR2 and VEGFR3) gene expression was studied in patients with myelodysplastic syndrome (MDS) to evaluate the possible prognostic role of the expression of these genes. Gene expression levels were determined using peripheral blood samples of 51 patients with MDS and 15 healthy volunteers by quantitative PCR. Expression of all VEGF and VEGFR genes was elevated in patients with MDS compared with healthy volunteers. No association of VEGF-A expression with the hemoglobin content in peripheral blood was found. The analyses of gene expression in patients with MDS stratified by risk groups according to the International Prognostic Scoring System showed progressive augmentation of VEGF-A gene expression from low to high-risk groups and VEGFR1 and VEGFR2 expression from intermediate-1 to high-risk groups. The statistically significant difference in survival time of patients with high and low levels of VEGFR1 expression was revealed. VEGF-A/VEGFR1 expression may be important for risk evaluation of patients with MDS.

Differential dependency of human glioblastoma cells on vascular endothelial growth factor‑A signaling via neuropilin‑1

Despite the high expression of neuropilin-1 (NRP-1) in human glioblastoma (GB), the understanding of its function as a co-receptor of vascular endothelial growth factor receptors (VEGFRs) in angiogenesis is currently limited. Therefore, the aim of the present study was to elucidate the non-classical function of NRP-1 expression in human GB. Expression patterns of NRP-1 and VEGF-A were determined by sandwich ELISA, western blot analysis, or immunohistochemistry. Differential dependency of GB cells following ablation of VEGF-A signaling was validated in vitro and in vivo. Cellular mechanism responsible for distinct response to VEGF-A signaling was evaluated by western blotting and immune-precipitation analysis. Prognostic implications were assessed using IHC analysis. GB cells exhibited differing sensitivity to silencing of vascular endothelial growth factor (VEGF)-A signaling, which resulted in a distinct expression pattern of wild-type or chondroitin-sulfated NRP-1. VEGF-A-sensitive GB exhibited the physical interaction between wild-type NRP-1 and FMS related receptor tyrosine kinase 1 (Flt-1) whereas VEGF-A-resistant GB exhibited chondroitin-sulfated NRP-1 without interaction with Flt-1. Eliminating the chondroitin sulfate modification in NRP-1 led to re-sensitization to VEGF-A signaling, and chondroitin sulfate modification was found to be associated with an adverse prognosis in patients with GB. The present study identified the distinct functions of NRP-1 in VEGF-A signaling in accordance with its unique expression type and interaction with Flt-1. The present research is expected to provide a strong basis for targeting VEGF-A signaling in patients with GB, with variable responses.

Role of angiogenesis in beta-cell epithelial-mesenchymal transition in chronic pancreatitis-induced diabetes

Clinical evidence suggests that patients with chronic pancreatitis (CP) are prone to development of diabetes (chronic pancreatitis-related diabetes; CPRD), whereas the underlying mechanisms are not fully determined. Recently, we showed that the gradual loss of functional beta-cells in a mouse model for CPRD, partial pancreatic duct ligation (PDL), results from a transforming growth factor β1 (TGFβ1)-triggered beta-cell epithelial-mesenchymal transition (EMT), rather than from apoptotic beta-cell death. Here, the role of angiogenesis in CPRD-associated beta-cell EMT was addressed. We detected enhanced angiogenesis in the inflamed pancreas from CP patients by bioinformatic analysis and from PDL-mice. Inhibition of angiogenesis by specific antisera for vascular endothelial growth factor receptor 2 (VEGFR2), DC101, did not alter the loss of beta-cells and the fibrotic process in PDL-pancreas. However, DC101-mediated inhibition of angiogenesis abolished pancreatitis-induced beta-cell EMT and rendered it to apoptotic beta-cell death. Thus, our data suggest that angiogenesis promotes beta-cell survival in the inflamed pancreas, while suppression of angiogenesis turns beta-cell EMT into apoptotic beta-cell death. This finding could be informative during development of intervention therapies for CPRD.

Inhibition of Vascular Endothelial Growth Factor Receptors 1 and 2 Attenuates Natural Killer Cell and Innate Immune Responses in an Experimental Model for Obliterative Bronchiolitis

Obliterative bronchiolitis (OB) after lung transplantation is a nonreversible, life-threatening complication. We investigated the role of vascular endothelial growth factor receptor (VEGFR)-1 and -2 in the development of obliterative airway disease (OAD), an experimental model for OB. The nonimmunosuppressed recipients underwent transplantation with fully major histocompatibility complex mismatched heterotopic tracheal allografts and received VEGFR-1 and -2-specific monoclonal antibodies either alone or in combination or rat IgG as a control. The treatment with VEGFR-1- or -2-blocking antibody significantly decreased intragraft mRNA expression of natural killer cell activation markers early after transplantation. This was followed by reduced infiltration of CD11b⁺ cells and CD4⁺ T cells as well as down-regulated mRNA expression of proinflammatory chemokines and profibrotic growth factors. However, blocking of both VEGFR-1 and -2 was necessary to reduce luminal occlusion. Furthermore, concomitant inhibition of the calcineurin activation pathway almost totally abolished the development of OAD. This study proposes that blocking of VEGF receptors blunted natural killer cell and innate immune responses early after transplantation and attenuated the development of OAD. The results of this study suggest that further studies on the role of VEGFR-1 and -2 blocking in development of obliterative airway lesions might be rewarding.

Angiogenesis in Lymph Nodes Is a Critical Regulator of Immune Response and Lymphoma Growth

Tumor-induced remodeling of the microenvironment in lymph nodes (LNs) includes the formation of blood vessels, which goes beyond the regulation of metabolism, and shaping a survival niche for tumor cells. In contrast to solid tumors, which primarily rely on neo-angiogenesis, hematopoietic malignancies usually grow within pre-vascularized autochthonous niches in secondary lymphatic organs or the bone marrow. The mechanisms of vascular remodeling in expanding LNs during infection-induced responses have been studied in more detail; in contrast, insights into the conditions of lymphoma growth and lodging remain enigmatic. Based on previous murine studies and clinical trials in human, we conclude that there is not a universal LN-specific angiogenic program applicable. Instead, signaling pathways that are tightly connected to autochthonous and infiltrating cell types contribute variably to LN vascular expansion. Inflammation related angiogenesis within LNs relies on dendritic cell derived pro-inflammatory cytokines stimulating vascular endothelial growth factor-A (VEGF-A) expression in fibroblastic reticular cells, which in turn triggers vessel growth. In high-grade B cell lymphoma, angiogenesis correlates with poor prognosis. Lymphoma cells immigrate and grow in LNs and provide pro-angiogenic growth factors themselves. In contrast to infectious stimuli that impact on LN vasculature, they do not trigger the typical inflammatory and hypoxia-related stroma-remodeling cascade. Blood vessels in LNs are unique in selective recruitment of lymphocytes via high endothelial venules (HEVs). The dissemination routes of neoplastic lymphocytes are usually disease stage dependent. Early seeding via the blood stream requires the expression of the homeostatic chemokine receptor CCR7 and of L-selectin, both cooperate to facilitate transmigration of tumor and also of protective tumor-reactive lymphocytes via HEV structures. In this view, the HEV route is not only relevant for lymphoma cell homing, but also for a continuous immunosurveillance. We envision that HEV functional and structural alterations during lymphomagenesis are not only key to vascular remodeling, but also impact on tumor cell accessibility when targeted by T cell-mediated immunotherapies.

New Insights into Diffuse Large B-Cell Lymphoma Pathobiology

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma (NHL), accounting for about 40% of all cases of NHL. Analysis of the tumor microenvironment is an important aspect of the assessment of the progression of DLBCL. In this review article, we analyzed the role of different cellular components of the tumor microenvironment, including mast cells, macrophages, and lymphocytes, in the tumor progression of DLBCL. We examined several approaches to confront the available pieces of evidence, whereby three key points emerged. DLBCL is a disease of malignant B cells spreading and accumulating both at nodal and at extranodal sites. In patients with both nodal and extranodal lesions, the subsequent induction of a cancer-friendly environment appears pivotal. The DLBCL cell interaction with mature stromal cells and vessels confers tumor protection and inhibition of immune response while delivering nutrients and oxygen supply. Single cells may also reside and survive in protected niches in the nodal and extranodal sites as a source for residual disease and relapse. This review aims to molecularly and functionally recapitulate the DLBCL–milieu crosstalk, to relate niche and pathological angiogenic constitution and interaction factors to DLBCL progression.

B-cell non-Hodgkin lymphoma: importance of angiogenesis and antiangiogenic therapy

Angiogenesis is critical for the initiation and progression of solid tumors, as well as hematological malignancies. While angiogenesis in solid tumors has been well characterized, a large body of investigation is devoted to clarify the impact of angiogenesis on lymphoma development. B-cell non-Hodgkin lymphoma (B-NHL) is the most common lymphoid malignancy with a highly heterogeneity. The malignancy remains incurable despite that the addition of rituximab to conventional chemotherapies provides substantial improvements. Several angiogenesis-related parameters, such as proangiogenic factors, circulating endothelial cells, microvessel density, and tumor microenvironment, have been identified as prognostic indicators in different types of B-NHL. A better understanding of how these factors work together to facilitate lymphoma-specific angiogenesis will help to design better antiangiogenic strategies. So far, VEGF-A monoclonal antibodies, receptor tyrosine kinase inhibitors targeting VEGF receptors, and immunomodulatory drugs with antiangiogenic activities are being tested in preclinical and clinical studies. This review summarizes recent advances in the understanding of the role of angiogenesis in B-NHL, and discusses the applications of antiangiogenic therapies.

Bevacizumab synergises with the BCL 2 inhibitor venetoclax to effectively treat B-cell non-Hodgkin's lymphoma

OBJECTIVES

Our present study has shown a potential role for VEGF-A-mediated autocrine signalling to promote survival and proliferation of SU-DHL-6 cells, but the cells could not undergo apoptosis but rather decrease proliferation after bevacizumab treatment. Therefore, we would like to further study the antitumour efficacy of venetoclax (BCL2 inhibitor) in combination with bevacizumab in B-cell NHL.

METHODS

The human cytokine antibody array, RT-qPCR, Western blot, ELISA, apoptosis assay and xenografted mouse model et al were used.

RESULTS

We described a unique phenomenon that SU-DHL-6 cells showed cell density-dependent survival and growth. Then, we suggested the expression of VEGF-A was positively correlated with the cell density using a human cytokine antibody array and indicated an important role of VEGF-A in the survival and proliferation of SU-DHL-6 cells. Additionally, xenografted SU-DHL-6 cells formed tumours in mice that grew in response to VEGF stimulation. GEO data set also suggested that high VEGF-A expression reflected poor prognosis. The combination therapy with bevacizumab and navitoclax could significantly induce of cell death in vitro and reduce the tumour size and weight with well tolerated in vivo.

CONCLUSIONS

Our findings propose a novel combined strategy in which bevacizumab synergises with the BCL2 inhibitor venetoclax that is effective against B-cell NHL.

The promising role of monoclonal antibodies for immunotherapy of the HIV-associated cancer, non-Hodgkin lymphoma

Association between HIV/AIDS and some of the cancers such as lymphomais is well known. Relative risk for developing non-Hodgkin lymphoma (NHL) increases 60-200 folds in HIV-infected individuals. Diffuse large B cell lymphoma (DLBCL), primary effusion lymphoma (PEL), Burkitt's lymphoma (BL) and Plasmablastic Lymphoma (PBL) are among the most frequent subtypes. During the last century, scientists found that the immune system could potentially detect and destroy cancer cells. Therefore, they started a new field of study, which is named immunotherapy. There are different immunotherapeutic methods, among which therapeutic antibodies, such as Brentuximabvedotin (Adcetris), Ibritumomabtiuxetan (Zevalin) and rituximab (Rituxan), used for treatment of NHLs showed promising results. In this article, we will review the immunotherapeutic option, monoclonal antibodies, for treatment of HIV-associated NHLs as well as their recent clinical status. We will also discuss the selective monoclonal antibody for each subtype of NHLs.

Macrophage-Induced Lymphangiogenesis and Metastasis following Paclitaxel Chemotherapy Is Regulated by VEGFR3

While chemotherapy strongly restricts or reverses tumor growth, the response of host tissue to therapy can counteract its anti-tumor activity by promoting tumor re-growth and/or metastases, thus limiting therapeutic efficacy. Here, we show that vascular endothelial growth factor receptor 3 (VEGFR3)-expressing macrophages infiltrating chemotherapy-treated tumors play a significant role in metastasis. They do so in part by inducing lymphangiogenesis as a result of cathepsin release, leading to VEGF-C upregulation by heparanase. We found that macrophages from chemotherapy-treated mice are sufficient to trigger lymphatic vessel activity and structure in naive tumors in a VEGFR3-dependent manner. Blocking VEGF-C/VEGFR3 axis inhibits the activity of chemotherapy-educated macrophages, leading to reduced lymphangiogenesis in treated tumors. Overall, our results suggest that disrupting the VEGF-C/VEGFR3 axis not only directly inhibits lymphangiogenesis but also blocks the pro-metastatic activity of macrophages in chemotherapy-treated mice.

•

Chemotherapy promotes macrophage colonization of tumors

•

Macrophages induce lymphangiogenesis in chemotherapy-treated tumors

•

Macrophages secrete cathepsins, VEGF-C, and heparanase in a VEGFR3-dependent manner

•

Blocking VEGFR3 in macrophages inhibits lymphangiogenesis and subsequent metastasis

Vascular endothelial growth receptor 1 acts as a stress-associated protein in the therapeutic response to thalidomide

Thalidomide (THD) exhibits antitumor effects in several types of cancer. However, the failure of THD to inhibit tumor growth has also been observed in a number of murine models in vivo. The mechanism involved in the therapeutic failure of THD remains unclear. The present study demonstrated that, accompanied by growth-arresting and apoptosis-inducing effects (P<0.05), THD upregulated vascular endothelial growth factor receptor 1 (VEGFR1) expression levels in CT26 murine colorectal carcinoma cell lines. This in vitro phenomenon was also observed in various other cell lines, including human umbilical vein endothelial cells, SW480, SW620 and HCT116. Reactive oxygen species (ROS) levels were increased compared with those in the untreated control when cells were exposed to THD (P<0.05). Furthermore, results suggested that ROS suppression may have provoked the induction of VEGFR1 expression to some extent. In addition, the results revealed that THD failed to inhibit CT26 tumor growth in vivo and the expression of VEGFR1 protein was elevated by THD treatment compared with the control group in the murine colorectal tumor model (P<0.05). The results of further experiments suggested that VEGFR1 was elevated in response to various stress-associated situations, including chemotherapy, radiotherapy and thermotherapy, which indicate that it may act as a stress-associated protein. The present findings provide a foundation for the future study of VEGFR1-targeted therapy to enhance the efficacy of current therapies.

[Analysis of VEGF-A/VEGFR1/VEGFR2 gene expression in patients with myelodysplastic syndrome]

AIM

To assess the significance of gene expression of the vascular endothelial growth factor-A (VEGF-A) and its interacting receptors VEGFR1 and VEGFR2 as potential diagnostic and prognostic molecular markers in patients with myelodysplastic syndrome (MDS).

MATERIAL AND METHODS

A real time polymerase chain reaction (RT-PCR) assay was used to investigate the gene expression of VEGF-A, VEGFR1, and VEGFR2 in the mononuclear cell fractions obtained from 24 patients with MDS.

RESULTS

The expression of the 3 genes was identified in all the patients examined. There was the highest expression level of the VEGF-A gene (p<0.0001), whereas the expression of the VEGFR1 gene was higher than that of the VEGFR2 gene (p<0.001). The expression of the VEGF-A gene proved to be higher in patients at a higher risk of acute leukemia and positively correlated with the expression levels of the VEGFR1 gene (p<0.05) rather than that of the VEGFR2 gene. At the same time, patients with higher VEGFR1 gene expression had significantly lower overall survival rates (r=-0.5; p<0.05). Patients with intermediate-2 or high-risk acute leukemia showed an increase in the average expression levels of VEGF-A and VEGFR1 and a reduction in VEGFR2 expression.

CONCLUSION

This investigation revealed correlations between the number of blast cells in patients with MDS and the expression levels of the VEGF-A gene and between the overall survival of patients with MDS and the expression levels of the VEGFR1 gene rather than those of the VEGF-A and VEGFR2 genes.

VEGF121, is predictor for survival in activated B-cell-like diffuse large B-cell lymphoma and is related to an immune response gene signature conserved in cancers

Tumor microenvironment including endothelial and immune cells plays a crucial role in tumor progression and has been shown to dramatically influence cancer survival. In this study, we investigated the clinical relevance of the gene expression of key mediators of angiogenesis, VEGF isoforms 121, 165, and 189, and their receptors (VEGFR-1 and R-2) in a cohort of patients (n = 37) with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) from the Collaborative Trial in Relapsed Aggressive Lymphoma (CORAL). In patients with ABC-like DLBCL, but not in patients with GCB-like DLBCL, low VEGF₁₂₁ expression was associated with a significantly better survival than in those with high VEGF₁₂₁ level: 4-year overall survival at 100% vs 36% (p = .011), respectively. A specific gene signature including 57 genes was correlated to VEGF₁₂₁ expression level and was analyzed using a discovery process in 1,842 GSE datasets of public microarray studies. This gene signature was significantly expressed in other cancer datasets and was associated with immune response. In conclusion, low VEGF₁₂₁ expression level was significantly associated with a good prognosis in relapsed/refractory ABC-like DLBCL, and with a well-conserved gene-expression profiling signature related to immune response. These findings pave the way for rationalization of drugs targeting immune response in refractory/relapsed ABC-like DLBCL.

Melatonin Reduces Angiogenesis in Serous Papillary Ovarian Carcinoma of Ethanol-Preferring Rats

Angiogenesis is a hallmark of ovarian cancer (OC); the ingrowth of blood vessels promotes rapid cell growth and the associated metastasis. Melatonin is a well-characterized indoleamine that possesses important anti-angiogenic properties in a set of aggressive solid tumors. Herein, we evaluated the role of melatonin therapy on the angiogenic signaling pathway in OC of an ethanol-preferring rat model that mimics the same pathophysiological conditions occurring in women. OC was chemically induced with a single injection of 7,12-dimethylbenz(a)anthracene (DMBA) under the ovarian bursa. After the rats developed serous papillary OC, half of the animals received intraperitoneal injections of melatonin (200 µg/100 g body weight/day) for 60 days. Melatonin-treated animals showed a significant reduction in OC size and microvessel density. Serum levels of melatonin were higher following therapy, and the expression of its receptor MT1 was significantly increased in OC-bearing rats, regardless of ethanol intake. TGFβ1, a transforming growth factor-beta1, was reduced only after melatonin treatment. Importantly, vascular endothelial growth factor (VEGF) was severely reduced after melatonin therapy in animals given or not given ethanol. Conversely, the levels of VEGF receptor 1 (VEGFR1) was diminished after ethanol consumption, regardless of melatonin therapy, and VEGFR2 was only reduced following melatonin. Hypoxia-inducible factor (HIF)-1α was augmented with ethanol consumption, and, notably, melatonin significantly reduced their levels. Collectively, our results suggest that melatonin attenuates angiogenesis in OC in an animal model of ethanol consumption; this provides a possible complementary therapeutic opportunity for concurrent OC chemotherapy.

VEGF-A, sVEGFR-1, and sVEGFR-2 in BCR-ABL negative myeloproliferative neoplasms

BACKGROUND AND OBJECTIVE

Data from the literature indicate the relationship between the bone marrow microvessel density and the blood parameters of angiogenesis. The aim of this study was to evaluate selected parameters of angiogenesis (VEGF-A, sVEGFR-1, and sVEGFR-2) and their correlations with white blood cells, platelets, and red blood cells.

MATERIALS AND METHODS

The study included 72 patients (mean age, 61.84 years) with myeloproliferative neoplasms (MPNs): essential thrombocythemia (ET) (n=46), polycythemia vera (PV) (n=19), and primary myelofibrosis (PMF) (n=7). Serum VEGF-A, sVEGFR-1, and sVEGFR-2 were determined using the ELISA assay.

RESULTS

We observed a significantly higher level of VEGF-A and reduced concentrations of sVEGFR-1 and sVEGFR-2 in the whole group of patients with MPNs as compared to controls. Detailed analysis confirmed significantly higher level of VEGF-A and lower concentration of sVEGFR-2 in each subgroups of MPNs patients. However, sVEGFR-1 concentrations were significantly lower only in PV and ET patients.

CONCLUSIONS

The study showed an increased level of VEGF-A, which may indicate the intensity of neoangiogenesis in the bone marrow. Decreased sVEGFR-1 and sVEGFR-2 in the blood of patients with MPNs may reflect consumption of these soluble receptors.

Concurrent Elevations of VEGF, Osteopontin and MCP-1 Serum Levels Are Independent Predictors of Survival in Patients with Diffuse Large B-Cell Lymphoma

BACKGROUND

Diffuse large B-cell lymphomas (DLBCL) are heterogeneous diseases, and the identification of additional DLBCL risk factors is especially important.

METHODS

In this pilot study, we determined pretreatment serum levels of vascular endothelial growth factor (VEGF), osteopontin (OPN) and macrophage chemotactic protein-1 (MCP-1) in 67 newly diagnosed DLBCL patients before treatment with standard chemoimmunotherapy and in 30 healthy persons.

RESULTS

Serum levels of all three cytokines were significantly elevated in untreated patients compared to controls. VEGF and OPN concentrations were higher in patients with advanced Ann Arbor stage, B symptoms, Eastern Cooperative Oncology Group score ≥2, International Prognostic Index (IPI) ≥3 and partial/no remission. A high MCP-1 level was associated with advanced stage, increased IPI and bone marrow infiltration. In univariate analysis, elevated OPN and VEGF, and concurrent elevation of all three biomarkers, were identified as significant predictors of poor survival. Multivariate Cox analysis revealed that elevated OPN combined with elevated VEGF levels was one of the best parameter subsets predicting poorest survival.

CONCLUSION

According to our preliminary results, serum levels of VEGF and OPN before treatment predict response to therapy and survival after chemoimmunotherapy, and may help to further stratify DLBCL patients into risk groups.

Assessing the therapeutic efficacy of VEGFR-1-targeted polymer drug conjugates in mouse tumor models

Polymer-drug conjugates that can actively target the tumor vasculature have emerged as an attractive technology for improving the therapeutic efficacy of cytotoxic drugs. We have recently provided, for the first time, in vivo evidence showing the significant advantage of the E-selectin-targeted N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-doxorubicin conjugate, P-(Esbp)-DOX, in inhibiting primary tumor growth and preventing the formation and development of cancer metastases. Here, we describe the design of a vascular endothelial growth factor receptor (VEGFR)-1-targeted HPMA copolymer-DOX conjugate (P-(F56)-DOX) that can actively and simultaneously target different cell types in the tumor microenvironment, such as endothelial cells (ECs), bone marrow-derived cells and many human cancer cells of diverse tumor origin. The VEGFR-1-targeted copolymer was tested for its binding, internalization and in vitro cytotoxicity in ECs (bEnd.3 and cEND cells) and cancer cells (B16-F10, 3LL and HT29). The in vivo anti-cancer activity of P-(F56)-DOX was then tested in two tumor-bearing mice (TBM) models (i.e., primary Lewis lung carcinoma (3LL) tumors and B16-F10 melanoma pulmonary metastases), relative to that of the E-selectin-targeted system (P-(Esbp)-DOX) that solely targets ECs. Our results indicate that the binding and internalization profiles of the VEGFR-1-targeted copolymer were superior towards ECs as compared to cancer cells and correlated well to the level of VEGFR-1 expression in cells. Accordingly, the VEGFR-1-targeted copolymer (P-(F56)-DOX) was more toxic towards bEnd.3 cells than to cancer cells, and exhibited significantly higher cytotoxicity than did the non-targeted control copolymer. P-(F56)-DOX inhibited 3LL tumor growth and significantly prolonged the survival of mice with B16-F10 pulmonary metastases. When compared to a system that actively targets only tumor vascular ECs, P-(F56)-DOX and P-(Esbp)-DOX exhibited comparable efficacy in slowing the growth of primary 3LL tumors and prolonging the survival of these mice. Still, P-(Esbp)-DOX had more pronounced anti-tumor activity in mice bearing B16-F10 lung metastases after a single intravenous injection, at an equivalent DOX dose. Overall, our results indicate that the VEGFR-1- and E-selectin-targeted drug delivery systems evaluated here show enhanced anti-cancer activity, and prolonged the survival of mice after a single intravenous injection. This is thus the first study comparing the anti-tumor activity of VEGFR-1- and E-selectin-targeted polymer drug conjugates in the same TBM models at an equivalent drug dose.

Lymphoma: immune evasion strategies

While the cellular origin of lymphoma is often characterized by chromosomal translocations and other genetic aberrations, its growth and development into a malignant neoplasm is highly dependent upon its ability to escape natural host defenses. Neoplastic cells interact with a variety of non-malignant cells in the tumor milieu to create an immunosuppressive microenvironment. The resulting functional impairment and dysregulation of tumor-associated immune cells not only allows for passive growth of the malignancy but may even provide active growth signals upon which the tumor subsequently becomes dependent. In the past decade, the success of immune checkpoint blockade and adoptive cell transfer for relapsed or refractory lymphomas has validated immunotherapy as a possible treatment cornerstone. Here, we review the mechanisms by which lymphomas have been found to evade and even reprogram the immune system, including alterations in surface molecules, recruitment of immunosuppressive subpopulations, and secretion of anti-inflammatory factors. A fundamental understanding of the immune evasion strategies utilized by lymphomas may lead to better prognostic markers and guide the development of targeted interventions that are both safer and more effective than current standards of care.

VEGFR-1 overexpression identifies a small subgroup of aggressive prostate cancers in patients treated by prostatectomy

The VEGFR-1 is suggested to promote tumor progression. In the current study we analyzed prevalence and prognostic impact of the VEGFR-1 by immunohistochemistry on a tissue microarray containing more than 3000 prostate cancer specimens. Results were compared to tumor phenotype, ETS-related gene (ERG) status, and biochemical recurrence. Membranous VEGFR-1 expression was detectable in 32.6% of 2669 interpretable cancers and considered strong in 1.7%, moderate in 6.7% and weak in 24.2% of cases. Strong VEGFR-1 expression was associated with TMPRSS2:ERG fusion status as determined by fluorescence in situ hybridization (FISH) and immunohistochemistry (p < 0.0001 each). Elevated VEGFR-1 expression was linked to high Gleason grade and advanced pT stage in TMPRSS2:ERG negative cancers (p = 0.0008 and p = 0.001), while these associations were absent in TMPRSS2:ERG positive cancers. VEGFR-1 expression was also linked to phosphatase and tensin homolog (PTEN) deletions. A comparison with prostate specific antigen (PSA) recurrence revealed that the 1.7% of prostate cancers with the highest VEGFR-1 levels had a strikingly unfavorable prognosis. This could be seen in all cancers, in the subsets of TMPRSS2:ERG positive or negative, PTEN deleted or undeleted carcinomas (p < 0.0001 each). High level VEGFR-1 expression is infrequent in prostate cancer, but identifies a subgroup of aggressive cancers, which may be candidates for anti-VEGFR-1 targeted therapy.

The growth and aggressive behavior of human osteosarcoma is regulated by a CaMKII-controlled autocrine VEGF signaling mechanism

Osteosarcoma (OS) is a hyperproliferative malignant tumor that requires a high vascular density to maintain its large volume. Vascular Endothelial Growth Factor (VEGF) plays a crucial role in angiogenesis and acts as a paracrine and autocrine agent affecting both endothelial and tumor cells. The alpha-Ca²⁺/Calmodulin kinase two (α-CaMKII) protein is an important regulator of OS growth. Here, we investigate the role of α-CaMKII-induced VEGF in the growth and tumorigenicity of OS. We show that the pharmacologic and genetic inhibition of α-CaMKII results in decreases in VEGF gene expression (50%) and protein secretion (55%), while α- CaMKII overexpression increases VEGF gene expression (250%) and protein secretion (1,200%). We show that aggressive OS cells (143B) express high levels of VEGF receptor 2 (VEGFR-2) and respond to exogenous VEGF (100nm) by increasing intracellular calcium (30%). This response is ameliorated by the VEGFR inhibitor CBO-P11, suggesting that secreted VEGF results in autocrine stimulated α-CaMKII activation. Furthermore, we show that VEGF and α-CaMKII inhibition decreases the transactivation of the HIF-1α and AP-1 reporter constructs. Additionally, chromatin immunoprecipitation assay shows significantly decreased binding of HIF-1α and AP-1 to their responsive elements in the VEGF promoter. These data suggest that α-CaMKII regulates VEGF transcription by controlling HIF-1α and AP-1 transcriptional activities. Finally, CBO-P11, KN-93 (CaMKII inhibitor) and combination therapy significantly reduced tumor burden in vivo. Our results suggest that VEGF-induced OS tumor growth is controlled by CaMKII and dual therapy by CaMKII and VEGF inhibitors could be a promising therapy against this devastating adolescent disease.

VEGFR-1 blockade disrupts peri-implantation decidual angiogenesis and macrophage recruitment

Background

Angiogenesis and macrophage recruitment to the uterus are key features of uterine decidualization; the progesterone-mediated uterine changes that allow for embryo implantation and initiation of pregnancy. In the current study, we characterized the expression of vascular endothelial growth factor receptor-1 (VEGFR-1) in macrophages and endothelial cells of the peri-implantation uterus and determined if VEGFR-1 function is required for decidual angiogenesis, macrophage recruitment, and/or the establishment of pregnancy.

Methods

Expression of VEGFR-1 in uterine endothelial cells and macrophages was determined with immunohistochemistry. To assess the effect of continuous VEGFR-1 blockade, adult female mice were given VEGFR-1 blocking antibody, MF-1, every 3 days for 18 days. After 6 doses, females were mated and a final dose of MF-1 was given on embryonic day 3.5. Endothelial cells and macrophages were quantified on embryonic day 7.5. Pregnancy was analyzed on embryonic days 7.5 and 10.5.

Results

F4/80⁺ macrophages are observed throughout the stroma and are abundant adjacent to the endometrial lumen and glands prior to embryo implantation and scatter throughout the decidua post implantation. VEGFR-1 expression is restricted to the uterine endothelial cells. F4/80⁺ macrophages were often found adjacent to VEGFR-1⁺ endothelial cells in the primary decidual zone. Continuous VEGFR-1 blockade correlates with a significant reduction in decidual vascular and macrophage density, but does not affect embryo implantation or maintenance of pregnancy up to embryonic day 10.5.

Conclusions

We found that VEGFR-1 functions in both decidual angiogenesis and macrophage recruitment to the implantation site during pregnancy. VEGFR-1 is expressed by endothelial cells, however blocking VEGFR-1 function in endothelial cells results in reduced macrophage recruitment to the uterus. VEGFR-1 blockade did not compromise the establishment and/or maintenance of pregnancy.

R-CHOP with or without bevacizumab in patients with previously untreated diffuse large B-cell lymphoma: final MAIN study outcomes

Vascular endothelial growth factor is involved in lymphoma growth, suggesting a potential role for anti-vascular endothelial growth factor therapies in hematologic malignancies. In this phase III study, patients with CD20-positive diffuse large B-cell lymphoma were randomized to rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone plus either placebo (R-CHOP) or bevacizumab (RA-CHOP). Treatment was administered every 21 (8 cycles) or 14 days (6 cycles plus 2 rituximab cycles) as per institutional practice. An early analysis of risk/benefit by the Data and Safety Monitoring Board showed that RA-CHOP increased cardiotoxicity without prolonging progression-free survival compared with R-CHOP, and the trial was stopped early. The study protocol was amended to allow for 12 additional months of follow up to evaluate safety. With 787 patients enrolled, median follow up was 23.7 and 23.6 months for R-CHOP and RA-CHOP, respectively. Median progression-free survival for R-CHOP and RA CHOP was 42.9 and 40.2 months, respectively (hazard ratio=1.09; P=0.49). The proportion of deaths was identical for R-CHOP (83 of 387, 21%) and RA-CHOP (82 of 390, 21%). Relative to R-CHOP, RA-CHOP had a higher rate of left ventricular ejection fraction perturbation (18% vs. 8%; odds ratio=2.51; 95% confidence interval (CI): 1.60-3.93) and congestive heart failure (16% vs. 7%; odds ratio=2.79; 95%CI: 1.72-4.54). Bevacizumab added to R-CHOP increased cardiac events, without increasing efficacy, arguing against further evaluation of RA-CHOP in patients with diffuse large B-cell lymphoma. The MAIN study is registered at clinicaltrials.gov identifier:00486759.

Rituximab with or without bevacizumab for the treatment of patients with relapsed follicular lymphoma

INTRODUCTION/BACKGROUND

Inhibition of tumor angiogenesis by the interruption of VEGF pathway signaling is of therapeutic value in several solid tumors. Preclinical evidence supports similar importance of the pathway in non-Hodgkin lymphoma. In this randomized phase II trial, we compared the efficacy and toxicity of rituximab with bevacizumab versus single-agent rituximab, in patients with previously-treated follicular lymphoma.

PATIENTS AND METHODS

Patients (n = 60) were randomized (1:1) to receive rituximab (375 mg/m(2) intravenously [I.V.] weekly for 4 weeks) either as a single agent or with bevacizumab (10 mg/kg I.V. on days 3 and 15). Patients with an objective response or stable disease at week 12 received 4 additional doses of rituximab (at months 3, 5, 7, and 9); patients who received rituximab/bevacizumab also received bevacizumab 10 mg/kg I.V. every 2 weeks for 16 doses.

RESULTS

After a median follow-up of 34 months, PFS was improved in patients who received rituximab/bevacizumab compared with patients who received rituximab alone (median 20.7 vs. 10.4 months respectively; HR, 0.40 (95% confidence interval [CI], 0.20-0.80); P = .007). Overall survival was also improved numerically (73% vs. 53% at 4 years), but did not reach statistical significance (HR, 0.40 (95% CI, 0.15-1.05); P = .055). The addition of bevacizumab increased the toxicity of therapy, but both regimens were well tolerated (no grade 4 toxicity).

CONCLUSION

The addition of bevacizumab to rituximab significantly improved PFS. The role of angiogenesis inhibition in the treatment of follicular lymphoma requires further definition in larger clinical trials.

Antitumor effects of bevacizumab in a microenvironment-dependent human adult T-cell leukemia/lymphoma mouse model

OBJECTIVE

The objective of this study was to evaluate the therapeutic potential of bevacizumab with or without systemic chemotherapy for adult T-cell leukemia/lymphoma (ATL) and clarify the significance of angiogenesis for ATL pathogenesis.

METHODS

NOD/Shi-scid, IL-2Rγ(null) (NOG) mice were used as recipients of tumor cells from a patient with ATL, which engraft and proliferate in a microenvironment-dependent manner. The ATL cells could be serially transplanted in NOG mice, but could not be maintained in in vitro cultures.

RESULTS

Injection of bevacizumab alone significantly increased necrosis and decreased vascularization in the tumor tissue. Levels of human soluble interleukin two receptor in the serum (reflecting the ATL tumor burden) of bevacizumab-treated mice were significantly lower than in untreated mice. Although bevacizumab monotherapy showed these clear anti-angiogenesis effects, it did not prolong survival. In contrast, injection of bevacizumab together with cyclophosphamide, doxorubicin, vincristine, prednisolone (CHOP) led to a significant prolongation of survival of the ATL mice relative to CHOP alone.

CONCLUSIONS

This is the first report to evaluate the efficacy of bevacizumab for ATL in a tumor microenvironment-dependent model. Bevacizumab therapy combined with chemotherapy could be a valuable treatment strategy for that subgroup of ATL probably depending to a large extent on angiogenesis via vascular endothelial growth factor.

VEGF-C and VEGF-D overexpression is more common in left-sided and well-differentiated colon adenocarcinoma

Tumour vessel network formation, including blood and lymph vessels, is a major step involved in the process of carcinogenesis. The discovery of vascular growth factors has led to a better understanding of tumour biology, thus, creating new possibilities for cancer treatment that targets angiogenesis within tumour-associated stroma, including therapy for colon cancer patients. The present study evaluated the relationships between increased expression of lymphangiogenic factors (VEGF-C and VEGF-D) and vessel density in the tumour-surrounding stroma, patient survival and other standard prognostic factors. The expression of VEGF-C and VEGF-D and vessel density were immunohistochemically assessed in 114 primary tumour specimens from colon adenocarcinoma patients after surgical resection between January 1, 2003 and December 31, 2008. Concomittant overexpression of VEGF-C and VEGF-D was found in 51 (44.7%) colon tumours and low expression was observed in 63 (55.3%) cases. Mean vessel density was 52.87/field. A significant correlation was found between the expression of factors influencing lymph vessel growth and increased vessel density in the tumour-surrounding stroma (p=0.03). A relationship between lymphangiogenic factor overexpression and left-sided tumour location was also found (p=0.00002). Overexpression of these factors was likely to occur in well-differentiated tumours (p=0.003). No association between patient survival and the expression levels of lymphangiogenic factors was observed. The study results indicate that the overexpression of lymphangiogenic factors tends to be associated with tumours of favourable prognosis, i.e. well-differentiated and those localized in the left-side of the colon.

Tumor cell response to bevacizumab single agent therapy in vitro

Background

Angiogenesis represents a highly multi-factorial and multi-cellular complex (patho-) physiologic event involving endothelial cells, tumor cells in malignant conditions, as well as bone marrow derived cells and stromal cells. One main driver is vascular endothelial growth factor (VEGFA), which is known to interact with endothelial cells as a survival and mitogenic signal. The role of VEGFA on tumor cells and /or tumor stromal cell interaction is less clear. Condition specific (e.g. hypoxia) or tumor specific expression of VEGFA, VEGF receptors and co-receptors on tumor cells has been reported, in addition to the expression on the endothelium. This suggests a potential paracrine/autocrine loop that could affect changes specific to tumor cells.

Methods

We used the monoclonal antibody against VEGFA, bevacizumab, in various in vitro experiments using cell lines derived from different tumor entities (non small cell lung cancer (NSCLC), colorectal cancer (CRC), breast cancer (BC) and renal cell carcinoma (RCC)) in order to determine if potential VEGFA signaling could be blocked in tumor cells. The experiments were done under hypoxia, a major inducer of VEGFA and angiogenesis, in an attempt to mimic the physiological tumor condition. Known VEGFA induced endothelial biological responses such as proliferation, migration, survival and gene expression changes were evaluated.

Results

Our study was able to demonstrate expression of VEGF receptors on tumor cells as well as hypoxia regulated angiogenic gene expression. In addition, there was a cell line specific effect in tumor cells by VEGFA blockade with bevacizumab in terms of proliferation; however overall, there was a limited measurable consequence of bevacizumab therapy detected by migration and survival.

Conclusion

The present study showed in a variety of in vitro experiments with several tumor cell lines from different tumor origins, that by blocking VEGFA with bevacizumab, there was a limited autocrine or cell-autonomous function of VEGFA signaling in tumor cells, when evaluating VEGFA induced downstream outputs known in endothelial cells.

The role of angiogenesis in human non-Hodgkin lymphomas

The role of angiogenesis in the growth of lymphomas and survival of patients with leukemias and other hematological malignancies has become evident since 1994. Angiogenic factors, such as vascular endothelial growth factor and its receptors together with other tumor microenvironment components, including myelo-monocytic cell, mast cells, endothelial progenitor cells, and circulating endothelial cells, have been shown to be important in the progression and maintenance of lymphoproliferative disorders. In this review article, we present an overview of the literature focusing on the relationship between angiogenesis and disease progression and the recent advantages in the antiangiogenic treatment in human non-Hodgkin lymphomas.

Inhibition of VEGFR-2 reverses type 1 diabetes in NOD mice by abrogating insulitis and restoring islet function

The dysregulation of receptor tyrosine kinases (RTKs) in multiple cell types during chronic inflammation is indicative of their pathogenic role in autoimmune diseases. Among the many RTKs, vascular endothelial growth factor receptor (VEGFR) stands out for its multiple effects on immunity, vascularization, and cell migration. Herein, we examined whether VEGFR participated in the pathogenesis of type 1 diabetes (T1D) in nonobese diabetic (NOD) mice. We found that RTK inhibitors (RTKIs) and VEGF or VEGFR-2 antibodies reversed diabetes when administered at the onset of hyperglycemia. Increased VEGF expression promoted islet vascular remodeling in NOD mice, and inhibition of VEGFR activity with RTKIs abrogated the increase in islet vascularity, impairing T-cell migration into the islet and improving glucose control. Metabolic studies confirmed that RTKIs worked by preserving islet function, as treated mice had improved glucose tolerance without affecting insulin sensitivity. Finally, examination of human pancreata from patients with T1D revealed that VEGFR-2 was confined to the islet vascularity, which was increased in inflamed islets. Collectively, this work reveals a previously unappreciated role for VEGFR-2 signaling in the pathogenesis of T1D by controlling T-cell accessibility to the pancreatic islets and highlights a novel application of VEGFR-2 antagonists for the therapeutic treatment of T1D.

c-myc but not Hif-1α-dependent downregulation of VEGF influences the proliferation and differentiation of HL-60 cells induced by ATRA

Vascular endothelial growth factor (VEGF) plays an important role in solid tumor growth, progression and metastasis as well as in the proliferation and differentiation of hematological malignancies. However, the molecular mechanism that modulates VEGF expression and secretion in leukemia cells has not yet to be elucidated. The purpose of the present study was to investigate the role of the signal pathway in modulating the expression of VEGF in HL-60 cells. Specific siRNAs targeting VEGF were transfected into HL-60 cells and the VEGF expression was measured with reverse transcription-polymerase chain reaction (RT-PCR) and western blot assay. The cell proliferation of HL-60 cells was detected by the cell counting kit-8 (CCK-8) assay and the differentiation of HL-60 cells induced by all-trans-retinoic acid (ATRA) was detected by the RT-PCR assay and flow cytometry assay for CD11b. The upstream transcription factors that were related to VEGF expression such as P53, SP-1, c-jun, VHL, cox-2, c-myc and stat3 were detected by RT-PCR assay. In addition, the chromatin immunoprecipitation (ChIP) assay was used to reveal the role of c-myc by binding the target gene VEGF. The results demonstrated the hypoxia-inducible factor 1α-related signaling pathway, not the same as in solid tumors, might not play a key role in modulating VEGF expression. c-myc contributes to the modulation of VEGF expression by targeting the promoter of VEGF, which was indicated by the ChIP assay. In conclusion, our data demonstrate that VEGF plays an important role in the differentiation and proliferation of HL-60 cells; c-myc-dependent downregulation of VEGF induced by ATRA contributes to the differentiation of HL-60 cells.

Tanycytic VEGF-A boosts blood-hypothalamus barrier plasticity and access of metabolic signals to the arcuate nucleus in response to fasting

The delivery of blood-borne molecules conveying metabolic information to neural networks that regulate energy homeostasis is restricted by brain barriers. The fenestrated endothelium of median eminence microvessels and tight junctions between tanycytes together compose one of these. Here, we show that the decrease in blood glucose levels during fasting alters the structural organization of this blood-hypothalamus barrier, resulting in the improved access of metabolic substrates to the arcuate nucleus. These changes are mimicked by 2-deoxyglucose-induced glucoprivation and reversed by raising blood glucose levels after fasting. Furthermore, we show that VEGF-A expression in tanycytes modulates these barrier properties. The neutralization of VEGF signaling blocks fasting-induced barrier remodeling and significantly impairs the physiological response to refeeding. These results implicate glucose in the control of blood-hypothalamus exchanges through a VEGF-dependent mechanism and demonstrate a hitherto unappreciated role for tanycytes and the permeable microvessels associated with them in the adaptive metabolic response to fasting.

High levels of vascular endothelial growth factor protein expression are associated with an increased risk of transfusion dependence in myelodysplastic syndromes

We evaluated the prognostic significance of vascular endothelial growth factor (VEGF) protein expression in 79 bone marrow biopsy specimens of patients with myelodysplastic syndromes (MDS). VEGF levels normalized for bone marrow cellularity (VEGF index [VEGFi]) were higher in the World Health Organization (WHO) classification-based prognostic scoring system (WPSS) "very high risk" than in the "very low risk" group (P = .009) and in patients with MDS with a poor karyotype than in the other cytogenetic risk groups (P = .015). High VEGFi (>75(th) percentile) predicted transfusion dependence (adjusted odds ratio, 10.38; 95% confidence interval, 1.02-106), and were correlated with leukemia-free survival and overall survival. The inclusion of VEGFi in the International Prognostic Scoring System and WPSS maintained its significant prognostic role in predicting leukemia-free and overall survival; it also seemed to improve the discrimination of the different prognostic classes, especially WPSS low-risk classes. Our findings support the clinical relevance of VEGFi expression in the bone marrow biopsy specimens of patients with MDS.

A phase 2 trial of standard-dose cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) and rituximab plus bevacizumab for patients with newly diagnosed diffuse large B-cell non-Hodgkin lymphoma: SWOG 0515

S0515 was a phase 2 trial to determine whether the addition of bevacizumab to cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) plus rituximab (R-CHOP) would improve progression-free survival (PFS) without adding significant toxicity in patients with newly diagnosed advanced diffuse large B-cell lymphoma. A total of 73 patients were enrolled. For the 64 eligible patients, median age was 68 years, and 60% had International Prognostic Index scores more than or equal to 3. The observed 1- and 2-year PFS estimates were 77% and 69%, respectively. These PFS estimates were not statistically different from the expected PFS for this population if treated with R-CHOP alone. Grade 3 or higher toxicities were observed in 81% of patients, including 2 grade 5 events. The majority of serious toxicities were hematologic but also included 5 patients with gastrointestinal perforations, 4 patients with thrombotic events, and 11 patients who developed grade 2 or 3 left ventricular dysfunction. Higher baseline urine VEGF and plasma VCAM levels correlated with worse PFS and overall survival. In conclusion, the addition of bevacizumab to R-CHOP chemotherapy was not promising in terms of PFS and resulted in increased serious toxicities, especially cardiac and gastrointestinal perforations. This study is registered at www.clinicaltrials.gov as #NCT00121199.

Potent antitumor effects of bevacizumab in a microenvironment-dependent human lymphoma mouse model

We established a mouse model of microenvironment-dependent human lymphoma, and assessed the therapeutic potential of bevacizumab, an antitumor agent acting on the microenvironment. NOD/Shi-scid, IL-2Rγ^null (NOG) mice were used as recipients of primary tumor cells from a patient with diffuse large B-cell lymphoma (DLBCL), which engraft and proliferate in a microenvironment-dependent manner. The lymphoma cells could be serially transplanted in NOG mice, but could not be maintained in in vitro cultures. Injection of bevacizumab together with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone) significantly increased necrosis and decreased vascularization in the tumor, compared with CHOP alone. Levels of human soluble interleukin-2 receptor (sIL2R) in the serum of bevacizumab+CHOP-treated mice (reflecting the DLBCL tumor burden) were significantly lower than in CHOP recipients. Mice receiving bevacizumab monotherapy also showed significant benefit in terms of tumor necrosis and vascularization, as well as decreased serum sIL2R concentrations. The present DLBCL model reflects the human DLBCL in vivo environment more appropriately than current mouse models using established tumor cell lines. This is the first report to evaluate the efficacy of bevacizumab in such a tumor microenvironment-dependent model. Bevacizumab may be a potential treatment strategy for DLBCL patients.

Sorafenib, a multikinase inhibitor, is effective in vitro against non-Hodgkin lymphoma and synergizes with the mTOR inhibitor rapamycin

Non-Hodgkin lymphoma (NHL) represents a heterogenous group of neoplasias originating from lymphoid cells. Increased angiogenesis and expression of Vascular Endothelial Growth Factor (VEGF) and its receptors (VEGFR) have been found to be associated with NHL disease progression. Increase in VEGF and other cytokines stimulate signaling cascades, including the Ras/Raf/Mek/Erk pathway, resulting in increased proliferation and decreased apoptosis. Here, we report the in vitro antilymphoma activity of sorafenib, an inhibitor of VEGFR and Raf kinase. Sorafenib induced potent cytotoxicity in NHL cell lines and patient samples. This induction of cytotoxicity was associated with a corresponding increase in apoptotic cell death. Mechanism of action of sorafenib was investigated in follicular (DoHH2) and Burkitt lymphoma (Raji) cell lines. pStat3, pAkt, Mcl1, and Xiap were downregulated in both cell lines, whereas pErk decreased in Raji but not in DoHH2 cells following sorafenib treatment. IL6 was unable to prevent sorafenib induced repression of pStat3, pAkt, Mcl1, and Bcl-Xl. Sorafenib in combination with an mTORC1 inhibitor rapamycin demonstrated synergy in inducing cytotoxicity in NHL cells. Sorafenib/rapamycin combination resulted in downregulation of pAkt, pmTOR, p-p70S6K, p4EBP1, pGSK3β, Mcl1, and Bcl-Xl. On the basis of our results, a clinical trial is underway using sorafenib with everolimus in NHL patients.

VEGFA and VEGFR2 genetic polymorphisms and survival in patients with diffuse large B cell lymphoma

We evaluated the impact of functional polymorphisms in the vascular endothelial growth factor A (VEGFA) and vascular endothelial growth factor 2 (VEGFR2) genes on the survival of patients with diffuse large B cell lymphoma (DLBCL). Five potentially functional polymorphisms in the VEGFA (rs699947, rs2010963 and rs3025039) and VEGFR2 (rs1870377 and rs2305948) genes were assessed in 494 DLBCL patients treated with rituximab plus CHOP chemotherapy. The associations of genotype and haplotype with overall survival (OS) and progression-free survival (PFS) were analyzed. Of the five polymorphisms, VEGFR2 rs1870377T>A was significantly associated with both OS and PFS; in the dominant model, patients with the AA + TA genotypes had significantly better OS (P = 0.002) and PFS (P = 0.004) than those with the TT genotype. The association between significantly better OS and the AA + TA genotypes was observed separately in patients with low (0-2; P = 0.035) and high (3-5; P = 0.043) International Prognostic Index scores. Multivariate analysis showed that, relative to the AA + TA genotypes, the TT genotype was an independent prognostic factor for poor OS (HR, 1.71; 95% CI, 1.21-2.43; P = 0.002) and PFS (HR, 1.57; 1.13-2.17; P = 0.004). Other independent significant predictors of survival in patients with DLBCL were International Prognostic Index score, age > 60 years, lactate dehydrogenase concentration >normal, extranodal disease >1 and presence of B symptoms. The VEGFR2 rs1870377 polymorphism might affect survival in patients with DLBCL, suggesting that angiogenesis might be related to poor survival in these patients.

Involvement of the Syk-mTOR pathway in follicular lymphoma cell invasion and angiogenesis

Follicular lymphoma (FL) is the second-most common non-Hodgkin's lymphoma. The disease affects the lymph nodes, and 50% of patients present with bone marrow infiltration; however, the mechanisms involved in dissemination of the disease are not yet known. We previously reported that FL cells display an overexpression of Syk, a tyrosine kinase involved in many cellular processes including cell migration. Therefore, we sought to explore its role in the invasive process. Here, we show that FL patients display higher matrix metalloproteinase (MMP)-9 and vascular endothelial growth factor (VEGF) levels than healthy donors. Moreover, using Syk small interfering RNA and the Syk inhibitor R406, we demonstrate that, in FL cells, Syk is involved in the regulation of MMP-9 and VEGF expression, and that invasion and angiogenesis is mediated through a phosphatidylinositol-3 kinase (PI3K)-mammalian target of rapamycin module. Finally, using a FL xenograft mouse model we observe that fostamatinib (R788), inhibits MMP-9 expression and angiogenesis in vivo. Altogether, this study provides strong evidence that Syk represents an encouraging therapeutic target in FL and suggests the potential use of fostamatinib as an anti-invasive and anti-angiogenic drug.

Blockade of VEGFR1 and 2 suppresses pathological angiogenesis and vascular leakage in the eye

Objective

VEGFR1 and 2 signaling have both been increasingly shown to mediate complications of ischemic retinopathies, including retinopathy of prematurity (ROP), age-related macular degeneration (AMD), and diabetic retinopathy (DR). This study evaluates the effects of blocking VEGFR1 and 2 on pathological angiogenesis and vascular leakage in ischemic retinopathy in a model of ROP and in choroidal neovascularization (CNV) in a model of AMD.

Materials and Methods

Neutralizing antibodies specific for mouse VEGFR1 (MF1) and VEGFR2 (DC101) were administrated systemically. CNV was induced by laser photocoagulation and assessed 14d after laser treatment. Retinal NV was generated in oxygen-induced ischemic retinopathy (OIR) and assessed at p17. NV quantification was determined by measuring NV tufts and vascular leakage was quantified by measuring [³H]-mannitol leakage from blood vessels into the retina. Gene expression was measured by real-time quantitative (Q)PCR.

Results

VEGFR1 and VEGFR2 expressions were up-regulated during CNV pathogenesis. Both MF1 and DC101 significantly suppressed CNV at 50 mg/kg: DC101 suppressed CNV by 73±5% (p<0.0001) and MF1 by 64±6% (p = 0.0002) in a dosage-dependent manner. The combination of MF1 and DC101 enhanced the inhibitory efficacy and resulted in an accumulation of retinal microglia at the CNV lesion. Similarly, both MF1 and DC101 significantly suppressed retinal NV in OIR at 50 mg/kg: DC101 suppressed retinal NV by 54±8% (p = 0.013) and MF1 by 50±7% (p<0.0002). MF1 was even more effective at inhibiting ischemia-induced BRB breakdown than DC101: the retina/lung leakage ratio for MF1 was reduced by 73±24%, p = 0.001 and for DC101 by 12±4%, p = 0.003. The retina/renal leakage ratio for MF1 was reduced by 52±28%, p = 0.009 and for DC101 by 13±4%, p = 0.001.

Conclusion

Our study provides further evidence that both VEGFR1 and 2 mediate pathological angiogenesis and vascular leakage in these models of ocular disease and suggests that antagonist antibodies to these receptor tyrosine kinases (RTKs) are potential therapeutic agents.

Angiogenic markers in canine lymphoma tissues do not predict survival times in chemotherapy treated dogs

Angiogenesis, which is essential for malignancies to progress, depends on various signalling proteins including vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptors 1 and 2 (VEGFR-1 and VEGFR-2). Microvessel density (MVD) is frequently used to evaluate angiogenesis. This study assessed the relationship between expression of VEGF, VEGFR-1 and VEGFR-2, MVD and the survival time in dogs with lymphoma. VEGF, VEGFR-1 and VEGFR-2 expression was evaluated immunohistochemically and microvessel profiles were counted in 34 lymphoma samples. Seventy-nine percent of the samples showed high VEGF expression and 62% were highly positive for VEGFR-1; VEGFR-2 immunoreactivity was mostly negative. Dogs treated with chemotherapy had a median survival time of 266days, but no significant relationships were found between overall survival time, MVD and expression of VEGF, VEGFR-1 or VEGFR-2. In this study, VEGF its receptors and the MVD were no prognostic factors in dogs with lymphoma.

Sunitinib in relapsed or refractory diffuse large B-cell lymphoma: a clinical and pharmacodynamic phase II multicenter study of the NCIC Clinical Trials Group

There are limited effective therapies for most patients with relapsed diffuse large B-cell lymphoma (DLBCL). We conducted a phase II trial of the multi-targeted vascular endothelial growth factor receptor (VEGFR) kinase inhibitor, sunitinib, 37.5 mg given orally once daily in adult patients with relapsed or refractory DLBCL. Of 19 enrolled patients, 17 eligible patients were evaluable for toxicity and 15 for response. No objective responses were seen and nine patients achieved stable disease (median duration 3.4 months). As a result, the study was closed at the end of the first stage. Grades 3-4 neutropenia and thrombocytopenia were observed in 29% and 35%, respectively. There was no relationship between change in circulating endothelial cell numbers (CECs) and bidimensional tumor burden over time. Despite some activity in solid tumors, sunitinib showed no evidence of response in relapsed/refractory DLBCL and had greater than expected hematologic toxicity.

ZFAT is a critical molecule for cell survival in mouse embryonic fibroblasts

ZFAT was originally identified as an immune-related transcriptional regulator containing 18 C2H2-type zinc-finger domains and one AT-hook. ZFAT is highly conserved among species and functions as an anti-apoptotic molecule in the lymphoblastic leukemia cell line, MOLT-4. We recently demonstrated that ZFAT is an essential molecule for hematopoietic differentiation in blood islands through the direct regulation of particular transcriptional factors, including Tal1, for endothelial cell assembly, and for the branch point formation of capillary-like structures. However, the molecular mechanisms underlying the anti-apoptotic function of ZFAT remain unknown. Here, we report that ZFAT knockdown by small interfering RNA induced apoptosis in mouse embryonic fibroblasts (MEFs). This response had been similarly observed for MOLT-4 cells. To explore the molecular mechanisms for ZFAT in anti-apoptotic function in both MEFs and MOLT-4 cells, microarray expression analysis and quantitative RT-PCR were done. Of interest was that Bcl-2 and Il6st were identified as commonly down-regulated genes by the depletion of ZFAT for both MEFs and MOLT-4 cells. These results suggest that ZFAT is a critical molecule for cell survival in MEFs and MOLT-4 cells at least in part through the regulation of the apoptosis involved in the BCL-2- and IL6st-mediated pathways. Further elucidation of the molecular functions for ZFAT might shed light on the cellular programs in the mesoderm-derived cells.

Increased expression of vascular endothelial growth factor receptor 1 correlates with VEGF and microvessel density in Philadelphia chromosome-negative myeloproliferative neoplasms

Aims

The authors investigated vascular endothelial growth factor receptor 1 (VEGFR-1) protein expression in a series of Philadelphia chromosome-negative myeloproliferative neoplasms (Ph- MPNs) and its correlations with microvessel density (MVD) and vascular endothelial growth factor (VEGF).

Methods

83 bone marrow biopsies of Ph- MPNs patients, including 27 essential thrombocythaemia (ET), 21 polycythaemia vera (PV) and 35 primary myelofibrosis (PMF), and 10 normal controls (NCs) were investigated by immunohistochemistry.

Results

Patients with PV and PMF showed an increased MVD (PV: 20.1±10.6; PMF: 25.8±6.5) compared with those with ET or NCs (ET: 10.4±4.6; NCs: 7±3.4). VEGFR-1 expression was increased in Ph- MPNs, particularly in PV and PMF (NCs: 0.07±0.03; ET: 0.15±0.09; PV: 0.31±0.2; PMF: 0.31±0.04). VEGF expression parallelled VEGFR-1 and resulted increased in Ph- MPNs (NCs: 0.08±0.04; ET: 0.13±0.06; PV: 0.29±0.2; PMF: 0.31±0.15) and higher in post-polycythaemic myelofibrosis and in the fibrotic stage of PMF than in the non-fibrotic phases of both diseases. VEGFR-1 protein expression correlated with MVD and VEGF expression in Ph- MPNs. VEGFR-1 and VEGF were expressed by the same bone marrow populations: megakaryocytes, macrophages and immature myeloid precursors showed a moderate to strong immunostaining intensity in both Ph- MPNs and NCs. The erythroid precursors were not immunoreactive.

Conclusions

VEGFR-1 and VEGF were increased and co-localised in megakaryocytes, macrophages and myeloid precursors of Ph- MPNs. This finding supports the hypothesis of a VEGF/VEGFR-1 autocrine loop in the neoplastic cells of Ph- MPNs.