VEGF/VEGFR2 interaction down-regulates matrix metalloproteinase-9 via STAT1 activation and inhibits B chronic lymphocytic leukemia cell migration

CD38/NAD+ glycohydrolase and associated antigens in chronic lymphocytic leukaemia: From interconnected signalling pathways to therapeutic strategies

Chronic lymphocytic leukaemia (CLL) is a heterogenous disease characterized by the accumulation of neoplastic CD5+/CD19+ B lymphocytes. The spreading of the leukaemia relies on the CLL cell's ability to survive in the blood and migrate to and proliferate within the bone marrow and lymphoid tissues. Some patients with CLL are either refractory to the currently available therapies or relapse after treatment; this emphasizes the need for novel therapeutic strategies that improving clinical responses and overcome drug resistance. CD38 is a marker of a poor prognosis and governs a set of survival, proliferation and migration signals that contribute to the pathophysiology of CLL. The literature data evidence a spatiotemporal association between the cell surface expression of CD38 and that of other CLL antigens, such as the B-cell receptor (BCR), CD19, CD26, CD44, the integrin very late antigen 4 (VLA4), the chemokine receptor CXCR4, the vascular endothelial growth factor receptor-2 (VEGF-R2), and the neutrophil gelatinase-associated lipocalin receptor (NGAL-R). Most of these proteins contribute to CLL cell survival, proliferation and trafficking, and cooperate with CD38 in multilayered signal transduction processes. In general, these antigens have already been validated as therapeutic targets in cancer, and a broad repertoire of specific monoclonal antibodies and derivatives are available. Here, we review the state of the art in this field and examine the therapeutic opportunities for cotargeting CD38 and its partners in CLL, e.g. by designing novel bi-/trispecific antibodies.

Anti-angiogenic effects of aqueous extract from Agrostemma githago L. seed in human umbilical vein endothelial cells via regulating Notch/VEGF, MMP2/9, ANG2, and VEGFR2

Abnormal angiogenesis contributes to the pathogenesis of various diseases. The medicinal usage of Agrostemma githago L. seed (A. githago herein) has been stated in traditional medicine. This study aims to investigate the anti-angiogenic potential of aqueous extract of A. githago. In order to test the effect of A. githago extract, its impact on HUVECs, T98G, and HGF2PI2 cells was assessed by looking at cellular viability, changes in the distribution of cells in different phases of the cell cycle, induction of oxidative stress, and apoptosis. In addition, the release of VEGF, ANG2, and MMP2/9 factors, along with the expressions of the critical Notch signaling pathway players and VEGF receptors (VEGFR), was measured. Furthermore, a γ-secretase inhibitor (LY411575) was applied to determine whether Notch inhibition restores A. githago effects. As a further characterization, total phenolic and flavonoid contents of A. githago were estimated, and five triterpene saponin compounds were identified using LC-ESI-MS. In response to A. githago extract, a reduction in total cell viability, along with the induction of ROS and apoptosis, was detected. Exposure to the A. githago extract could modulate the release of VEGF and ANG2 from T98G and HUVECs, respectively. In addition, A. githago reduced the release of MMP2/9. Furthermore, Notch1, DLL4, and HEY2 transcripts and protein expressions were up-regulated, while VEGFR2 was down-regulated in treated HUVEC cells. Treatment with the A. githago extract resulted in a dose-dependent inhibition of AKT phosphorylation. Inhibition of Notch signaling retrieved the viability loss, reduced intracellular ROS, and alleviated the impaired tube formation in A. githago-treated HUVECs. Overall, these data underscore the anti-angiogenic potential of A. githago via inducing apoptosis, modifying the expression levels of VEGF/VEGFR2, and impacting the release of MMP2/9 and ANG2, effects that are most probably modulated through the Notch/VEGF signaling axis.

Inhibitors of gelatinases (MMP-2 and MMP-9) for the management of hematological malignancies

Matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) are collectively known as gelatinases whereas MMP-2 is gelatinase-A and MMP-9 is termed as gelatinase-B. Gelatinases and other matrix metalloproteinases (MMPs) have long been associated with solid tumor invasion, metastasis and angiogenesis. However, there is paucity of data available regarding the role of gelatinases in hematological malignancies. Recent studies have shown that gelatinases activities or functions are correlated with hematological malignancies. Strategies for designing more specific gelatinase inhibitors like catalytic (CAT) domain inhibitors and hemopexin (PEX) domain inhibitors as well as signaling pathway based or gelatinase expression inhibitors had been reported against hematologic malignant cells. Several substrate based non-selective to non-substrate based relatively selective synthetic matrix metalloproteinase inhibitors (MMPIs) had been developed. Few MMPIs had reached in clinical trials during the period of 1990s-2000s. Unfortunately the anti-tumor and anti-metastatic efficacies of these MMPIs were not justified with patients having several advanced stage solid tumor cancers in any substantial number of clinical trials. Till date not a single MMPI passed phase III clinical trials designed for advanced metastatic cancers due to adverse events as well as lack of ability to show uniformity in disease prolongation. With the best of our knowledge no clinical trial study has been reported with small molecule synthetic inhibitors against hematological malignancies. This review looks at the outcome of clinical trials of MMPIs for advanced stage solid tumors. This can therefore, act as a learning experience for future development of successful gelatinase inhibitors for the management of hematological malignancies.

Metalloproteinases in Ovarian Cancer

Proteases play a crucial role in the progression and metastasis of ovarian cancer. Pericellular protein degradation and fragmentation along with remodeling of the extracellular matrix (ECM) is accomplished by numerous proteases that are present in the ovarian tumor microenvironment. Several proteolytic processes have been linked to cancer progression, particularly those facilitated by the matrix metalloproteinase (MMP) family. These proteases have been linked to enhanced migratory ability, extracellular matrix breakdown, and development of support systems for tumors. Several studies have reported the direct involvement of MMPs with ovarian cancer, as well as their mechanisms of action in the tumor microenvironment. MMPs play a key role in upregulating transcription factors, as well as the breakdown of structural proteins like collagen. Proteolytic mechanisms have been shown to enhance the ability of ovarian cancer cells to migrate and adhere to secondary sites allowing for efficient metastasis. Furthermore, angiogenesis for tumor growth and development of metastatic implants is influenced by upregulation of certain proteases, including MMPs. While proteases are produced normally in vivo, they can be upregulated by cancer-associated mutations, tumor-microenvironment interaction, stress-induced catecholamine production, and age-related pathologies. This review outlines the important role of proteases throughout ovarian cancer progression and metastasis.

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.

Anti-VEGF Drugs in the Treatment of Multiple Myeloma Patients

The interaction between the bone marrow microenvironment and plasma cells plays an essential role in multiple myeloma progression and drug resistance. The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway in vascular endothelial cells activates and promotes angiogenesis. Moreover, VEGF activates and promotes vasculogenesis and vasculogenic mimicry when it interacts with VEGF receptors expressed in precursor cells and inflammatory cells, respectively. In myeloma bone marrow, VEGF and VEGF receptor expression are upregulated and hyperactive in the stromal and tumor cells. It has been demonstrated that several antiangiogenic agents can effectively target VEGF-related pathways in the preclinical phase. However, they are not successful in treating multiple myeloma, probably due to the vicarious action of other cytokines and signaling pathways. Thus, the simultaneous blocking of multiple cytokine pathways, including the VEGF/VEGFR pathway, may represent a valid strategy to treat multiple myeloma. This review aims to summarize recent advances in understanding the role of the VEGF/VEGFR pathway in multiple myeloma, and mainly focuses on the transcription pathway and on strategies that target this pathway.

Biomarkers of cavernous angioma with symptomatic hemorrhage

BACKGROUNDCerebral cavernous angiomas (CAs) with a symptomatic hemorrhage (CASH) have a high risk of recurrent hemorrhage and serious morbidity.METHODSEighteen plasma molecules with mechanistic roles in CA pathobiology were investigated in 114 patients and 12 healthy subjects. The diagnostic biomarker of a CASH in the prior year was derived as that minimizing the Akaike information criterion and validated using machine learning, and was compared with the prognostic CASH biomarker predicting bleeding in the subsequent year. Biomarkers were longitudinally followed in a subset of cases. The biomarkers were queried in the lesional neurovascular unit (NVU) transcriptome and in plasma miRNAs from CASH and non-CASH patients.RESULTSThe diagnostic CASH biomarker included a weighted combination of soluble CD14 (sCD14), VEGF, C-reactive protein (CRP), and IL-10 distinguishing CASH patients with 76% sensitivity and 80% specificity (P = 0.0003). The prognostic CASH biomarker (sCD14, VEGF, IL-1β, and sROBO-4) was confirmed to predict a bleed in the subsequent year with 83% sensitivity and 93% specificity (P = 0.001). Genes associated with diagnostic and prognostic CASH biomarkers were differentially expressed in CASH lesional NVUs. Thirteen plasma miRNAs were differentially expressed between CASH and non-CASH patients.CONCLUSIONShared and unique biomarkers of recent symptomatic hemorrhage and of future bleeding in CA are mechanistically linked to lesional transcriptome and miRNA. The biomarkers may be applied for risk stratification in clinical trials and developed as a tool in clinical practice.FUNDINGNIH, William and Judith Davis Fund in Neurovascular Surgery Research, Be Brave for Life Foundation, Safadi Translational Fellowship, Pritzker School of Medicine, and Sigrid Jusélius Foundation.

Angiotensin 1-7 modulates molecular and cellular processes central to the pathogenesis of prostate cancer

Angiotensin 1–7 (Ang1–7) is an endogenous bioactive component of the renin-angiotensin system (RAS). In addition to its cardiovascular properties, its anti-proliferative and anti-angiogenic traits are believed to play important roles in carcinogenesis. The present study examines the influence of Ang1–7 on processes associated with development and progression of prostate cancer cells. Our findings indicate that while Ang1–7 (1 nM; 48 h) can effectively reduce cell proliferation in DU-145, it can induce a significant decrease in the expression of MKI67 in LNCaP. In both cell lines we also observed a reduction in colony size in soft agar assay. A various changes in gene expression were noted after exposure to Ang1–7: those of anti- and pro-apoptotic agents and the NF-kB family of transcription factors, as well as mesenchymal cell markers and vascular endothelial growth factor A (VEGFA). In addition, Ang1–7 was found to modulate cell adhesion and matrix metallopeptidase (MMP) activity. Changes were also observed in the levels of angiotensin receptors and sex steroid hormone receptors. Ang1–7 reduced the levels of estrogen receptor alpha gene (ESR1) and increased the expression of estrogen receptor beta gene (ESR2) in all prostate cancer cells; it also up-regulated androgen receptor (AR) expression in androgen-sensitive cells but contradictory effect was observed in androgen- irresponsive cell lines. In summary, the results confirm the existence of complex network between the various elements of the local RAS and the molecular and cellular mechanisms of prostate cancerogenesis. The response of cancer cells to Ang1–7 appears to vary dependently on the dose and time of incubation as well as the aggressiveness and the hormonal status of cells.

Liposome-Encapsulated Hemoglobin Accelerates Skin Wound Healing in Diabetic dB/dB Mice

Since liposome-encapsulated hemoglobin with high O₂ affinity (h-LEH, P₅₀ O₂  = 10 mm Hg) has been reported to accelerate skin wound healing in normal mice, it was tested in dB/dB mice with retarded wound healing, as seen in human diabetics. Two full-thickness dorsal wounds 6 mm in diameter encompassed by silicone stents were created in dB/dB mice. Two days later (day 2), the animals were randomly assigned to receive intravenous h-LEH (2 mL/kg, n = 7) or saline (2 mL/kg, n = 7). The same treatment was repeated 4 days after wounding (day 4), and the size of the skin lesions was analyzed by photography, surface perfusion was detected by Laser-Doppler imager, and plasma cytokines and chemokines were determined on days 0, 2, 4, and 7, when all animals were euthanized for morphological studies. The size of the ulcer compared to the skin defect or silicone stent became significantly reduced on days 4 and 7 in mice treated with h-LEH (47 ± 8% of original size), similar to the level in wild-type mice, compared to saline-treated dB/dB mice (68 ± 18%, P < 0.01). Mice treated with h-LEH had significantly attenuated inflammatory cytokines, increased surface perfusion, and increased Ki67 expression on day 7 in accordance with the ulcer size reduction, while there was no significant difference in chemokines, histological granulation, epithelial thickness, and granulocyte infiltration detected by immunohistochemical staining in the ulcer between the treatment groups. The results suggest that h-LEH (2 mL/kg) early after wounding may accelerate skin wound healing in dB/dB mice to levels equivalent to wild-type mice probably via mechanism(s) involving reduced hypoxia, increased surface perfusion, suppressed inflammation, accelerated in situ cell proliferation and protein synthesis.

Overexpression of Hiwi Inhibits the Growth and Migration of Chronic Myeloid Leukemia Cells

Chronic myeloid leukemia (CML) is a hematopoietic malignancy characterized by dysregulated growth and proliferation of hematopoietic stem/progenitor cells in bone marrow and excessive expansion of hematopoietic compartments in peripheral blood. Expression deletion of Hiwi, a human Piwi homolog, has been reported to be implicated in leukemogenesis. We here explored Hiwi's role in CML pathogenesis by determining how and whether its forced overexpression could affect CML cell growth and migration. The present results showed that lentivirus-mediated overexpression of Hiwi significantly suppressed cell proliferation and induced obvious apoptosis in K562 cells, a CML line cell line. Tumors in BALB/c nude mice generated by the K562 cells expressing Hiwi were much smaller than those formed by the control cells. Like in vitro, Hiwi upregulation induced cell apoptosis in the tumor tissues in vivo. Additionally, Hiwi elevation suppressed K562 cell migration and inhibited the activity and expression of matrix metalloproteinase-2 and -9. In summary, our study demonstrates that Hiwi overexpression inhibits CML cell growth and migration, providing insights into its role in CML pathogenesis.

Tumor angiogenesis: MMP-mediated induction of intravasation- and metastasis-sustaining neovasculature

Metastasis is a distinct stage of cancer progression that requires the development of angiogenic blood vessels serving as conduits for tumor cell dissemination. An accumulated body of evidence indicates that metastasis-supporting neovasculature should possess certain structural characteristics allowing for the process of tumor cell intravasation, an active entry of cancer cells into the vessel interior. It appears that the development of tumor vessels with lumens of a distinctive size and support of these vessels by a discontinuous pericyte coverage constitute critical microarchitectural requirements to: (a) provide accessible points for vessel wall penetration by primary tumor cells; (b) provide enough lumen space for a tumor cell or cell aggregate upon intravasation; and (c) allow for sufficient rate of blood flow to carry away intravasated cells from the primary tumor to the next, proximal or distal site. This review will primarily focus on the functional roles of matrix metalloproteinases (MMPs), which catalytically trigger the development of an intravasation-sustaining neovasculature at the early stages of tumor growth and are also required for the maintenance of a metastasis-supporting state of blood vessels at later stages of cancer progression.

RIG-I suppresses the migration and invasion of hepatocellular carcinoma cells by regulating MMP9

The retinoic acid-induced protein I (Rig-I/Ddx58), (RIG-I) initiates a signaling cascade that induces innate immune defences which is associated with the production of type I interferons (IFNs) and inflammatory cytokines to establish an antiviral state. Aberrant RIG-I signaling leads to inflammation, autoimmune diseases and cancer. However, the role of RIG-I in hepatocellular carcinoma (HCC) is still unknown. Here, we observed that RIG-I expression was downregulated in HCC tissues and loss of RIG-I expression was correlated with poor clinicopathological features. Additionally, we demonstrated that patients with positive RIG-I expression had a better 3-year survival and RIG-I was an independent factor for predicting the prognosis of HCC patients. Elevated RIG-I expression inhibited the proliferation, migration, and invasion of HCC. Inhibiting RIG-I with its specific siRNA was able to attenuate the malignant behavior of HCC cells. Moreover, RIG-I inhibited the invasive behavior through downregulating matrix metalloproteinase-9 (MMP9). Mechanistically, RIG-I enhances IFN-α response by amplifying IFN-α effecter signaling via strengthening STAT1 activation. Addressing this pathway, we identified that RIG-I may serve as a prognostic marker and that MMP9 may be a potential target of RIG-I in HCC.

VEGF-mediated suppression of cell proliferation and invasion by miR-410 in osteosarcoma

MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression. The aberrant expression of miRNA has become a major focus in cancer research. This study aimed to investigate the importance of miR-410 in the diagnosis and therapy of osteosarcoma (OS). Western blot analysis showed that the expression of VEGF was higher in Saos-2 and MG-63 cells than that in three other OS cell lines. We also found that miR-410 was lowly expressed and inversely correlated with VEGF expression in OS specimens. Over-expression of miR-410 had a greater repression on VEGF expression than other candidate VEGF-targeting miRNAs. Luciferase reporter assay demonstrated that miR-410 directly decreased VEGF expression by targeting its 3'-untranslated region. Further investigation demonstrated the regulation of miR-410 in OS cells via VEGF. In vitro MTT assay, Transwell, and flow cytometry showed that transfection of the miR-410 expression plasmid inhibited cell proliferation and contributed to apoptosis in OS cells. Moreover, restoration of VEGF reversed the effect of miR-410 on OS cells, and upregulated the expression of phosphorylated AKT. Finally, overexpression of miR-410 also showed a negative effect on tumor growth in vivo. Our findings suggest a cooperative relationship between miR-410 and VEGF in OS cell regulation. This information may help researchers to better understand miRNA regulation in cancer and provide a rationale for developing miRNA-based strategies for OS treatment.

Vascular endothelial growth factor A (VEGFA) gene polymorphisms have an impact on survival in a subgroup of indolent patients with chronic lymphocytic leukemia

Vascular endothelial growth factor (VEGF)-mediated angiogenesis contributes to the pathogenesis of B-cell chronic lymphocytic leukaemia (CLL). We investigated the impact of VEGFA gene diversity on the clinical outcome of patients with this disease. A VEGFA haplotype conformed by positions rs699947 (–1540C>A), rs833061 (–460T>C) and rs2010963 (405C>G) and two additional single-nucleotide polymorphisms (SNPs), rs3025039 (936C>T) and rs25648 (1032C>T), were analysed in 239 patients at the time of their CLL diagnosis. Here, we showed that homozygosity for rs699947/rs833061/rs2010963 ACG haplotype (ACG^+/+ genotype) correlated with a reduced survival in CLL patients (ACG^+/+ vs other genotypes: HR = 2.3, p = 0.002; recessive model). In multivariate analysis, the ACG^+/+ genotype was identified as a novel independent prognostic factor (HR = 2.1, p = 0.005). Moreover, ACG homozygosity subdivided patients with CLL with otherwise indolent parameters into prognostic subgroups with different outcomes. Specifically, patients carrying the ACG^+/+ genotype with mutated IgV_H, very low and low-risk cytogenetics, initial clinical stage, CD38 negative status or early age at diagnosis showed a shorter survival (ACG^+/+ vs other genotypes: HR = 3.5, p = 0.035; HR = 3.4, p = 0.001; HR = 2.2, p = 0.035; HR = 3.4, p = 0.0001 and HR = 3.1, p = 0.009, respectively). In conclusion, VEGFA ACG^+/+ genotype confers an adverse effect in overall survival in CLL patients with an indolent course of the disease. These observations support the biological and prognostic implications of VEGFA genetics in CLL.

STAT1 and STAT3 in tumorigenesis: A matter of balance

The transcription factors STAT1 and STAT3 appear to play opposite roles in tumorigenesis. While STAT3 promotes cell survival/proliferation, motility and immune tolerance and is considered as an oncogene, STAT1 mostly triggers anti-proliferative and pro-apoptotic responses while enhancing anti-tumor immunity. Despite being activated downstream of common cytokine and growth factor receptors, their activation is reciprocally regulated and perturbation in their balanced expression or phosphorylation levels may re-direct cytokine/growth factor signals from proliferative to apoptotic, or from inflammatory to anti-inflammatory. Here we review the functional canonical and non-canonical effects of STAT1 and STAT3 activation in tumorigenesis and their potential cross-regulation mechanisms.

Dual VEGF/VEGFR inhibition in advanced solid malignancies: clinical effects and pharmacodynamic biomarkers

Our prior phase I study of the combination of vascular endothelial growth factor (VEGF) antibody, bevacizumab, and VEGF receptor (VEGFR) inhibitor, sunitinib, in advanced solid tumors identified an encouraging response evaluation. An expansion phase of this study was thus undertaken to obtain further safety data, response assessment and characterization of pharmacodynamic biomarkers in melanoma, renal, and adrenal carcinoma patients. Patients with metastatic solid tumors received sunitinib (37.5 mg/d, 4 wk on/2 wk off) and bevacizumab (5 mg/kg intravenously every 2 wk). Responses were assessed every 2 cycles. Serum levels of angiogenic molecules were measured using ELISA assays. Twenty-two patients were enrolled, including 11 melanoma, 5 renal cell carcinoma (RCC), 5 adrenal cancer, and 1 angiosarcoma. Grade 3 or higher adverse events were observed in 15 patients, including hypertension (41%), thrombocytopenia (23%), and fatigue (14%). Three RCC patients, and 1 melanoma patient developed thrombotic microangiopathy (TMA). Partial response (PR) occurred in 21% patients, including melanoma (2), adrenal (1), and renal (1) carcinomas. Overall, 6 patients demonstrated some reduction in their tumor burden. Serum VEGF and several other proangiogenic proteins declined over the first 4 wk of treatment whereas the putative VEGF-resistant protein, prokineticin-2, increased over 10-fold. Occurrence of TMA related to dual VEGF/VEGFR inhibition can result from systemic or nephron specific injury even in non-renal malignancies. While the combination of sunitinib and bevacizumab was clinically efficacious in renal cell carcinoma and melanoma, the observance of microangiopathy, even in non-RCC patients, is a significant toxicity that precludes further clinical development.

Critical signal transduction pathways in CLL

Receptor tyrosine kinases (RTKs) are cell-surface transmembrane receptors that contain regulated kinase activity within their cytoplasmic domain and play a critical role in signal transduction in both normal and malignant cells. Besides B cell receptor (BCR) signaling in chronic lymphocytic leukemia (CLL), multiple RTKs have been reported to be constitutively active in CLL B cells, resulting in enhanced survival and resistance to apoptosis of the leukemic cells induced by chemotherapeutic agents. In addition to increased plasma levels of various types of cytokines/growth factors in CLL, we and others have detected that CLL B cells spontaneously produce multiple cytokines in vitro which may constitute an autocrine loop of RTK activation on the leukemic B cells. Moreover, aberrant expression and activation of non-RTKs, for example, Src/Syk kinases, induce resistance of the leukemic B cells to therapy. Based on current available knowledge, we detailed the impact of aberrant activities of various RTKs/non-RTKs on CLL B cell survival and the potential of using these signaling components as future therapeutic targets in CLL therapy.

A murine-human chimeric IgG antibody against vascular endothelial growth factor receptor 2 inhibits angiogenesis in vitro

Vascular endothelial growth factor receptor 2 (VEGFR2) has been reported to play an important role in angiogenesis and tumorigenesis. A murine anti-VEGFR2 mAb (A8H1) has been established in a previous study. To reduce the incompatibility of the murine mAb for human use, the chimeric anti-VEGFR2-IgG was developed by genetic recombination of the variable regions of the A8H1 antibody and the constant regions of human IgG, and was expressed in Sp2/0 cells transfected with the two recombinant vectors containing the heavy chain and the light chain regions. After screening, clone 2F12 was selected and was found to stably secrete the murine-human chimeric anti-VEGFR2-IgG (coded 2F12). This chimeric IgG maintained the specificity and the affinity of the parental murine antibody against VEGFR2, and effectively identified VEGFR2 expressed on the surface of HUVECs and BEL-7402 cells. Furthermore, the 2F12 antibody demonstrated inhibition of angiogenesis in vitro, such as proliferation, migration, invasion and tube formation of HUVECs. This murine-human chimeric IgG may be considered for further development as an anti-angiogenesis and anti-tumor agent.

Lenalidomide reduces survival of chronic lymphocytic leukemia cells in primary cocultures by altering the myeloid microenvironment

Lenalidomide treatment of primary CLL/nurse-like cell cocultures resulted in significantly decreased viability of CLL cells. Lenalidomide increased IL-10 levels, activation of STAT1, expression of ICAM-1, and migration-related genes, and reduced CLL cell motility.

Role of VEGF/VEGFR in the pathogenesis of leukemias and as treatment targets (Review)

Angiogenesis plays an important role in solid tumor growth, progression and metastasis. Evidence suggests that the progression of hematolymphoid malignancies also depends on the induction of new blood vessel formation under the influence of acute leukemia, myelodysplastic syndromes, myeloproliferative neoplasms, multiple myeloma and lymphomas. The vascular endothelial growth factor (VEGF) is the most important proangiogenic agent that activates receptors on vascular endothelial cells and promotes blood vessel regeneration. It has been demonstrated that VEGF/VEGF receptor (VEGFR) expression is upregulated in several types of hematolymphoid tumor cells accompanied with angiogenesis. The levels of VEGF/VEGFR are correlated with the treatment, relapse and prognosis of hematolymphoid tumors. In order for VEGF family and their receptors as antiangiogenic targets to treat solid tumors, several antiangiogenic agents targeting VEGF-related pathways have been used for the treatment of hematolymphoid malignancies in clinical trials. The results demonstrate a promising therapeutic intervention in multiple types of hematolymphoid tumors. This review aims to summarize recent advances in understanding the role of VEGF and angiogenesis in leukemias, mainly focusing on their upstream transcriptors, downstream targets and the correlation of VEGF/VEGFR with the treatment, relapse or prognosis of leukemia. The progress of VEGF and its receptors as attractive targets for therapies are also discussed in clinical application.

Angiogenic factors in chronic lymphocytic leukemia

Angiogenesis is a complex process controlled by the balance of a large number of regulating factors, the pro- and anti-angiogenic factors. Dysregulation of angiogenesis occurs in various pathologies and is one of the hallmarks for cancer. Recent emphasis on the microenvironment's influence in chronic lymphocytic leukemia (CLL) progression and drug resistance nurtures the interest in angiogenesis. Researchers have already identified a variety of angiogenic factors involved in the CLL, including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF), angiopoietin-2(Ang-2), thrombospondin-1 (TSP-1), as well as extracellular proteinases such as matrix metalloproteinase-9 (MMP-9). Besides modulating neovascularization, angiogenic factors also participate in the regulation of pro-survival effects of CLL cells. However, the precise mechanism involved still needs to be elucidated further. At present, the levels of some angiogenic factors are regarded as prognostic markers of the progression of CLL, although it is not widely used. Several anti-VEGF agents are currently under clinical trial. Advances in the understanding of the bases of angiogenesis regulators will be benefit for the comprehension of CLL pathogenesis and help to conquer the disease.

The mechanisms of cerebral vascular dysfunction and neuroinflammation by MMP-mediated degradation of VEGFR-2 in alcohol ingestion

OBJECTIVE

Blood-brain barrier (BBB) dysfunction caused by activation of matrix metalloproteinases (MMPs) is a pathological feature in vascular/neurological disease. We describe the mechanisms of BBB dysfunction and neuroinflammation as a result of MMP-3/9 activation and disruption of vascular endothelial growth factor (VEGF)-A/VEGFR-2 interaction, impairing effective angiogenesis.

METHODS AND RESULTS

We investigate the hypothesis in human brain endothelial cells and animal model of chronic alcohol ingestion. Proteome array analysis, zymography, immunofluorescence, and Western blotting techniques detected the activation, expression, and levels of MMP-3 and MMP-9. We found that degradation of VEGFR-2 and BBB proteins, for example, occludin, claudin-5, and ZO-1 by MMP-3/9, causes rupture of capillary endothelium and BBB leakiness. Impairment of BBB integrity was demonstrated by increased permeability of dye tracers and Fluo-3/calcein-AM-labeled monocyte adhesion or infiltration and decrease in transendothelial electric resistance. Alcohol-induced degradation of endothelial VEGFR-2 by MMP-3/9 led to a subsequent elevation of cellular/serum VEGF-A level. The decrease in VEGFR-2 with subsequent increase in VEGF-A level led to apoptosis and neuroinflammation via the activation of caspase-1 and IL-1β release. The use of MMPs, VEGFR-2, and caspase-1 inhibitors helped to dissect the underlying mechanisms.

CONCLUSIONS

Alcohol-induced MMPs activation is a key mechanism for dysfunction of BBB via degradation of VEGFR-2 protein and activation of caspase-1 or IL-1β release. Targeting VEGF-induced MMP-3/9 activation can be a novel preventive approach to vascular inflammatory disease in alcohol abuse.

Phase II trials of single-agent anti-VEGF therapy for patients with chronic lymphocytic leukemia

Between 2005 and 2008, we conducted separate phase II clinical testing of three distinct anti-VEGF therapies for patients with relapsed/refractory CLL. Collectively, 46 patients were accrued to trials of single-agent anti-VEGF antibody (bevacizumab, n = 13) or one of two receptor tyrosine kinase inhibitors (AZD2171, n = 15; sunitinib malate, n = 18). All patients have completed treatment. Patients received a median of two cycles of bevacizumab, AZD2171, or sunitinib malate. All three trials were closed early due to lack of efficacy. No complete or partial remissions were observed. Individually and collectively, these studies indicate that single-agent anti-VEGF therapy has minimal clinical activity for patients with relapsed/refractory CLL.