A novel peptide derived from human apolipoprotein E is an inhibitor of tumor growth and ocular angiogenesis

Angiogenesis is a hallmark of tumor development and metastasis and now a validated target for cancer treatment. We previously reported that a novel dimer peptide (apoEdp) derived from the receptor binding region of human apolipoprotein E (apoE) inhibits virus-induced angiogenesis. However, its role in tumor anti-angiogenesis is unknown. This study demonstrates that apoEdp has anti-angiogenic property in vivo through reduction of tumor growth in a mouse model and ocular angiogenesis in a rabbit eye model. Our in vitro studies show that apoEdp inhibits human umbilical vein endothelial cell proliferation, migration, invasion and capillary tube formation. We document that apoEdp inhibits vascular endothelial growth factor-induced Flk-1 activation as well as downstream signaling pathways that involve c-Src, Akt, eNOS, FAK, and ERK1/2. These in vitro data suggest potential sites of the apoE dipeptide inhibition that could occur in vivo.This is the first evidence that a synthetic dimer peptide mimicking human apoE has anti-angiogenesis functions and could be an anti-tumor drug candidate.     

Inhibition of angiogenesis and angiogenesis-dependent tumor growth by the cryptic kringle fragments of human apolipoprotein(a)

Apolipoprotein(a) (apo(a)) contains tandemly repeated kringle domains that are closely related to plasminogen kringle 4, followed by a single kringle 5-like domain and an inactive protease-like domain. Recently, the anti-angiogenic activities of apo(a) have been demonstrated both in vitro and in vivo. However, its effects on tumor angiogenesis and the underlying mechanisms involved have not been fully elucidated. To evaluate the anti-angiogenic and anti-tumor activities of the apo(a) kringle domains and to elucidate their mechanism of action, we expressed the last three kringle domains of apo(a), KIV-9, KIV-10, and KV, in Escherichia coli. The resultant recombinant protein, termed rhLK68, exhibited a dose-dependent inhibition of basic fibroblast growth factor-stimulated human umbilical vein endothelial cell proliferation and migration in vitro and inhibited the neovascularization in chick chorioallantoic membranes in vivo. The ability of rhLK68 to abrogate the activation of extracellular signal-regulated kinases appears to be responsible for rhLK68-mediated anti-angiogenesis. Furthermore, systemic administration of rhLK68 suppressed human lung (A549) and colon (HCT-15) tumor growth in nude mice. Immunohistochemical examination and in situ hybridization analysis of the tumors showed a significant decrease in the number of blood vessels and the reduced expression of vascular endothelial growth factor, basic fibroblast growth factor, and angiogenin, indicating that suppression of angiogenesis may have played a significant role in the inhibition of tumor growth. Collectively, these results suggest that a truncated apo(a), rhLK68, is a potent anti-angiogenic and anti-tumor molecule.     

Design,synthesis and biological evaluation of Lenalidomide derivatives as tumor angiogenesis inhibitor

Lenalidomide is a type of immunomodulatory agent with anti-tumor activity by mainly expressed in the anti-angiogenesis. In order to enhance the pharmacological activity of Lenalidomide, a series of Lenalidomide derivatives were designed as tumor angiogenesis inhibitors. The potential anti-angiogenesis targets of Lenalidomide derivatives were virtual screened on Auto-Dock 4.0 by using reverse docking method. The six target proteins, such as vascular endothelial growth factor receptor, epidermal growth factor receptor, fibroblast growth factor receptor, BCR-ABL tyrosine kinase, p38 mitogen activated protein kinase and metal protein kinase, were chosen as the targets. The Lenalidomide derivatives were synthesized by alkylated, acylated or sulfonylated Lenalidomide and verified by the ¹H NMR, ¹³C NMR and LC–MS. Their anti-cancer activities were detected by using CCK-8 in the esophageal carcinoma cell line EC9706. The results indicate that the inhibitory activities of Lenalidomide derivatives were higher than that of Lenalidomide.     

Knockdown of CD146 reduces the migration and proliferation of human endothelial cells

Our previous study has demonstrated that CD 146 molecule is a biomarker on vascular endothelium,which is involvedin angiogenesis and tumor growth.However the mechanism behind is not clear.Here we have for the first time devel-oped a novel CD146 blockade system using CD146 siRNA to study its function on endothelial cells.Our data showedthat CD146 siRNA specifically blocked the expression of CD146 on both mRNA and protein levels,leading to thesignificant suppression of HUVEC proliferation,adhesion and migration.These results demonstrate that CD146 playsa key role in vascular endothelial cell activity and angiogenesis,and CD146 siRNA can be used as a new inhibitor foranti-angiogenesis therapy.     

Monitoring therapeutic monoclonal antibodies in brain tumor

Bevacizumab induces normalization of abnormal blood vessels, making them less leaky. By binding to vascular endothelial growth factor, it indirectly attacks the vascular tumor mass. The optimal delivery of targeted therapies including monoclonal antibodies or anti-angiogenesis drugs to the target tissue highly depends on the blood-brain barrier permeability. It is therefore critical to investigate how drugs effectively reach the tumor. In situ investigation of drug distribution could provide a better understanding of pharmacological agent action and optimize chemotherapies for solid tumors. We developed an imaging method coupled to protein identification using matrix-assisted laser desorption/ionization mass spectrometry. This approach monitored bevacizumab distribution within the brain structures, and especially within the tumor, without any labeling.     

Monitoring therapeutic monoclonal antibodies in brain tumor

Bevacizumab induces normalization of abnormal blood vessels, making them less leaky. By binding to vascular endothelial growth factor, it indirectly attacks the vascular tumor mass. The optimal delivery of targeted therapies including monoclonal antibodies or anti-angiogenesis drugs to the target tissue highly depends on the blood-brain barrier permeability. It is therefore critical to investigate how drugs effectively reach the tumor. In situ investigation of drug distribution could provide a better understanding of pharmacological agent action and optimize chemotherapies for solid tumors. We developed an imaging method coupled to protein identification using matrix-assisted laser desorption/ionization mass spectrometry. This approach monitored bevacizumab distribution within the brain structures, and especially within the tumor, without any labeling.     

转移性结直肠癌抗血管生成靶向治疗的研究进展

近年来,由于各种新的化疗药物及分子靶向药物的使用,转移性结直肠癌(metastatic colorectal cancer,m CRC)的个体化治疗逐步取得了重要的成果。研究表明,抗血管生成靶向药物与化疗药物的联合使用作为转移性结直肠癌的一线治疗方案,可明显改善治疗效果,延长患者的生存时间。血管内皮生长因子(vascularendothelial growth factor,VEGF)是肿瘤血管生成过程中最主要的因子。贝伐单抗是通过基因工程技术得到的针对血管内皮生长因子-A(VEGF-A)的单克隆抗体,作为抗血管生成靶向药物用于转移性结直肠癌的临床治疗。本文对近年来转移性结直肠癌的抗血管生成靶向治疗,尤其是贝伐单抗治疗的相关研究进展进行综述并展望未来抗血管生成靶向治疗的发展前景。     

Apoptosis initiation and angiogenesis inhibition: melanoma targets for nanosecond pulsed electric fields

Many effective anti-cancer strategies target apoptosis and angiogenesis mechanisms. Applications of non-ionizing, nanosecond pulsed electric fields (nsPEFs) induce apoptosis in vitro and eliminate cancer in vivo; however in vivo mechanisms require closer analysis. These studies investigate nsPEF-induced apoptosis and anti-angiogenesis examined by fluorescent microscopy, immunoblots, and morphology. Six hours after treatment with one hundred 300 ns pulses at 40 kV/cm, cells transiently expressed active caspases indicating that caspase-mediated mechanisms. Three hours after treatment transient peaks in Histone 2AX phosphorylation coincided with terminal deoxynucleotidyl transferase dUTP nick end labeling positive cells and pyknotic nuclei, suggesting caspase-independent mechanisms on nuclei/DNA. Large DNA fragments, but not 180 bp fragmentation ladders, were observed, suggesting incomplete apoptosis. Nevertheless, tumor weight and volume decreased and tumors disappeared. One week after treatment, vessel numbers, vascular endothelial growth factor (VEGF), platelet derived endothelial cell growth factor (PD-ECGF), CD31, CD35 and CD105 were decreased, indicating anti-angiogenesis. The nsPEFs activate multiple melanoma therapeutic targets, which is consistent with successes of nsPEF applications for tumor treatment in vivo as a new cancer therapeutic modality.     

Ganoderma lucidum polysaccharides peptide inhibits the growth of vascular endothelial cell and the induction of VEGF in human lung cancer cell

Ganoderma lucidum Polysaccharide Peptide (Gl-PP) has shown some effects as anti-tumors in mice and potential anti-angiogenesis. In this study, we elucidated the possible mechanism of Gl-PP action on anti-angiogenesis of tumor. Our research indicated that the proliferation of HUVECs was inhibited by Gl-PP in a dose-dependent fashion, but not because of cytotoxicity. Flow cytometric studies revealed that Gl-PP treatment of HUVECs could induce cell apoptosis directly. Moreover, addition of Gl-PP also led to a reduction of Bcl-2 anti-apoptotic protein expression and an increase of Bax pro-apoptotic protein expression of HUVECs. Therefore, inducing cell apoptosis by Gl-PP might be the mechanism of inhibiting HUVEC proliferation. Human lung carcinoma cells PG when exposed to high dose of Gl-PP in hypoxia for 18 h resulted in a decrease in the secreted VEGF. Taken together, these findings support the hypothesis that the key attribute of the anti-angiogenic potential of Gl-PP is that it may directly inhibit vascular endothelial cell proliferation or indirectly decrease growth factor expression of tumor cells.     

New molecular mediators in tumor angiogenesis

Angiogenesis is essential for tumor growth and progression. It has been demonstrated that tumor growth beyond a size 1 to 2 mm³ requires the induction of new vessels. Angiogenesis is regulated by several endogenous stimulators and inhibitors of endothelial cell migration, proliferation and tube formation. Under physiological conditions these mediators of endothelial cell growth are in balance and vessel growth is limited. In fact, within the angiogenic balance endothelial cell turnover is sufficient to maintain a functional vascular wall but does not allow vessel growth. Tumor growth an progression has successfully been correlated to the serum concentration of angiogenic mediators. Furthermore, the vascular density of tumor tissues could be correlated to the clinical course of the disease in several tumor entities. Within the last years several new mediators of endothelial cell growth have been isolated e.g. angiopoietin 1, angiopoietin 2, midkine, pleiotropin, leptin and maspin. In this review we discuss the mechanisms leading to tumor angiogenesis and describe some of the newer mediators of endothelial cell stimulation and inhibition.     

A polypeptide from shark troponin I can inhibit angiogenesis and tumor growth

The shark troponin I gene (TnI) was found for the first time in this study to inhibit endothelial cell proliferation and angiogenesis. This shark TnI had 68.9% amino acid homology with human TnI, whereas the polypeptide from Lys91 to Leu123, which is thought to be the active site of TnI, had 78.8% homology with the corresponding fragment of human TnI. However, the polypeptide of shark had higher activity to inhibit the proliferation of HUVEC and tumor cell lines than that of human TnI. To investigate the anti-angiogenesis and anti-tumor effect of the shark TnI polypeptide, the DNA sequence of polypeptide (Lys91-Leu123) of white-spot catshark TnI(psTnI) was cloned and fused with the His-SUMO cDNA, followed by expression in Escherichia coli. After its purification by Ni²⁺ affinity chromatography, the fusion His-SUMO-psTnI protein was digested with the SUMO enzyme to release psTnI. The inhibitory ability of this recombinant shark TnI polypeptide for angiogenesis was confirmed by chicken embryo allantoic membrane (CAM) test and IHC analysis. It was also found by breast carcinoma xenograft study in Balb/c mice that this polypeptide could inhibit tumor growth in vivo.     

Site-dependent angiogenic cytokine production in human tumor xenografts

Tumor microenvironment plays a critical role in tumor growth, angiogenesis, and metastasis. Differences in site of tumor implantation result in differences in tumor growth, metastasis, as well as response to chemotherapy. We hypothesized that tumor-induced angiogenic growth factor production into the plasma will also be influenced by site of tumor implantation. We evaluated the site-dependent production of angiogenic growth factors in the plasma of tumor bearing animals at two different sites of implantation. Plasma levels of tumor necrosis factor-alpha (TNF-alpha), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) were evaluated in nude mice bearing A2780, SKOV-3, or OVCAR-3 human ovarian tumors, as well as Panc-1, AsPC-1, or BxPC-3 human pancreatic tumors grown as subcutaneous (SC) xenografts or in the intraperitoneal (IP) cavity. Plasma VEGF and bFGF levels produced by two ovarian tumor lines and two pancreatic tumor lines were substantially higher when the tumors were implanted in the IP cavity than in the SC space. These studies indicated that the site of tumor implantation was an important determinant in the production of plasma VEGF and bFGF levels. As more and more anti-angiogenic agents are developed, the need for appropriate animal models becomes apparent. These results suggest the demand for an appropriate model for the in vivo evaluation of anti-angiogenesis.     

Gekko-sulfated glycopeptide inhibits tumor angiogenesis by targeting basic fibroblast growth factor

Basic fibroblast growth factor (bFGF) is a therapeutic target of anti-angiogenesis. Here, we report that a novel sulfated glycopeptide derived from Gekko swinhonis Guenther (GSPP), an anticancer drug in traditional Chinese medicine, inhibits tumor angiogenesis by targeting bFGF. GSPP significantly decreased the production of bFGF in hepatoma cells by suppressing early growth response-1. GSPP inhibited the release of bFGF from extracellular matrix by blocking heparanase enzymatic activity. Moreover, GSPP competitively inhibited bFGF binding to heparin/heparan sulfate via direct binding to bFGF. Importantly, GSPP abrogated the bFGF-stimulated proliferation and migration of endothelial cells, whereas it had no inhibitory effect on endothelial cells in the absence of bFGF. Further study revealed that GSPP prevented bFGF-induced neovascularization and inhibited tumor angiogenesis and tumor growth in a xenograft mouse model. These results demonstrate that GSPP inhibits tumor angiogenesis by blocking bFGF production, release from the extracellular matrix, and binding to its low affinity receptor, heparin/heparan sulfate.     

RETRACTED ARTICLE: Signaling pathways in tumor vasculogenic mimicry

Solid tumor growth is dependent on the development of an adequate blood supply. For years, sprouting angiogenesis has been considered as the exclusive mechanism of tumor vascularization. However, in recent years, another mechanism of tumor vascularization has been identified that does not involve endothelial cells, a process called vasculogenic mimicry (VM). VM describes the unique ability of highly aggressive tumor cells to form vessel-like networks by virtue of their high plasticity. VM has been observed in several tumor types, and its occurrence is strongly associated with poor prognosis. This review focuses on signaling molecules and cascades involved in VM. In addition, the clinical significance of VM regardless of anti-angiogenesis treatment modalities is described.     

Quantitative analysis of autocrine-regulated, matrix-induced, and tumor cell-stimulated endothelial cell migration using a silicon template compartmentalization technique.

Autocrine-regulated, matrix-induced, and tumor cell-stimulated endothelial cell migration was quantitatively analyzed using a two-dimensional, two-compartment coculture system. Silicon templates were used to subdivide 35-mm tissue culture dishes into two separate compartments. Endothelial cells were grown to confluence in the inner compartment and released from growth arrest by removal of the silicon template. The distance of endothelial cell outgrowth from the monolayer was measured in 24-h intervals. Endothelial cells from different vascular beds migrated with different migration rates (large vessel endothelial cells greater than hemangioendothelioma cells greater than microvessel endothelial cells). Prior coating of tissue culture wells with fibronectin, type I collagen, or type IV collagen and increasing serum concentrations strongly enhanced endothelial cell migration. Seeding tumor cells into the outer compartment prior to removal of the silicon template permitted the direct coculture analysis of tumor cell-induced endothelial cell migration. Microvascular endothelial cell migration was stimulated in a tumor cell number-dependent fashion, whereas large vessel endothelial cells could not consistently be stimulated by coculture with tumor cells. It is concluded that silicon templates offer a useful approach for the quantitative study of migration of anchorage-dependent cells, permitting follow-up measurements over several days, the study of matrix effects, and the direct coculture analysis of cell migration.     

Tumor cell-mediated neovascularization and lymphangiogenesis contrive tumor progression and cancer metastasis

Robust neovascularization and lymphangiogenesis have been found in a variety of aggressive and metastatic tumors. Endothelial sprouting angiogenesis is generally considered to be the major mechanism by which new vasculature forms in tumors. However, increasing evidence shows that tumor vasculature is not solely composed of endothelial cells (ECs). Some tumor cells acquire processes similar to embryonic vasculogenesis and produce new vasculature through vasculogenic mimicry, trans-differentiation of tumor cells into tumor ECs, and tumor cell–EC vascular co-option. In addition, tumor cells secrete various vasculogenic factors that induce sprouting angiogenesis and lymphangiogenesis. Vasculogenic tumor cells actively participate in the formation of vascular cancer stem cell niche and a premetastatic niche. Therefore, tumor cell-mediated neovascularization and lymphangiogenesis are closely associated with tumor progression, cancer metastasis, and poor prognosis. Vasculogenic tumor cells have emerged as key players in tumor neovascularization and lymphangiogenesis and play pivotal roles in tumor progression and cancer metastasis. However, the mechanisms underlying tumor cell-mediated vascularity as they relate to tumor progression and cancer metastasis remain unclear. Increasing data have shown that various intrinsic and extrinsic factors activate oncogenes and vasculogenic genes, enhance vasculogenic signaling pathways, and trigger tumor neovascularization and lymphangiogenesis. Collectively, tumor cells are the instigators of neovascularization. Therefore, targeting vasculogenic tumor cells, genes, and signaling pathways will open new avenues for anti-tumor vasculogenic and metastatic drug discovery. Dual targeting of endothelial sprouting angiogenesis and tumor cell-mediated neovascularization and lymphangiogenesis may overcome current clinical problems with anti-angiogenic therapy, resulting in significantly improved anti-angiogenesis and anti-cancer therapies.     

Inhibition of endothelial FAK activity prevents tumor metastasis by enhancing barrier function

Pharmacological focal adhesion kinase (FAK) inhibition prevents tumor growth and metastasis, via actions on both tumor and stromal cells. In this paper, we show that vascular endothelial cadherin (VEC) tyrosine (Y) 658 is a target of FAK in tumor-associated endothelial cells (ECs). Conditional kinase-dead FAK knockin within ECs inhibited recombinant vascular endothelial growth factor (VEGF-A) and tumor-induced VEC-Y658 phosphorylation in vivo. Adherence of VEGF-expressing tumor cells to ECs triggered FAK-dependent VEC-Y658 phosphorylation. Both FAK inhibition and VEC-Y658F mutation within ECs prevented VEGF-initiated paracellular permeability and tumor cell transmigration across EC barriers. In mice, EC FAK inhibition prevented VEGF-dependent tumor cell extravasation and melanoma dermal to lung metastasis without affecting primary tumor growth. As pharmacological c-Src or FAK inhibition prevents VEGF-stimulated c-Src and FAK translocation to EC adherens junctions, but FAK inhibition does not alter c-Src activation, our experiments identify EC FAK as a key intermediate between c-Src and the regulation of EC barrier function controlling tumor metastasis.     

Isoform of Vascular Endothelial Cell Growth Inhibitor （VEGI72-251） Increases Interleukin-2 Production by Activation of T Lymphocytes

The objective of this study is to investigate the characteristics of the recombinant variant ofhuman vascular endothelial cell growth inhibitor,VEGI_(72-251),and compare its biological activities with that ofits prototype VEGI_(24-174),The recombinant plasmid containing the variant VEGI_(72-251) gene was constructedand expressed in Escherichia coli.The effects of the expressed VEGI_(72-251) on cell proliferations were checkedin the human umbilical vein endothelial cell line and certain tumor cell lines (ECV304 and B 16).The inhibitionof VEGI_(72-251) on angiogenesis was detected in the chorioallantoic membrane of chick embryos.In comparisonwith VEGI_(24-174),the recombinant human VEGI_(72-251) seems to have no effect on the proliferation of endothelialcells and the angiogenesis of the chorioallantoic membrane in vitro.An enzyme-linked immunosorbent assay-based method was used for the measurement of interleukin-2 (IL-2) production by peripheral blood monocytes(PBMCs) treated with VEGI_(72-251).PBMCs were pretreated with VEGI_(72-251) (1.25-12.50μg/ml) for 24 h invitro,and the IL-2 concentration in PBMC medium was increased from 354 pg/ml to 1256 pg/ml.It can beconcluded that VEGI_(72-251) is able to increase the level of human IL-2 production by the activation of Tlymphocytes.Differing from VEGI_(24-174) on anti-angiogenesis,VEGI_(72-251) may serve as an anti-cancer factorthrough its activation of T lymphocytes.     

Inhibition of prostate tumor angiogenesis by the tumor suppressor CEACAM1

We have previously shown that CEACAM1, a cell-adhesion molecule, acts as a tumor suppressor in prostate carcinoma. Expression of CEACAM1 in prostate cancer cells suppresses their growth in vivo. However, CEACAM1 has no effect on the growth of prostate cancer cells in vitro. This difference suggests that the antitumor effect of CEACAM1 may be due to inhibition of tumor angiogenesis, perhaps by increased secretion of antiangiogenic molecules from the cells. In this study, we have demonstrated that expression of CEACAM1 in DU145 prostate cancer cells induced the production of a factor or factors that specifically blocked the growth of endothelial but not epithelial cells. Conditioned medium from the CEACAM1-expressing cells but not control luciferase-expressing cells inhibited endothelial cell migration up a gradient of stimulatory vascular endothelial growth factor in vitro and inhibited corneal neovascularization induced by basic fibroblast growth factor in vivo. Moreover, conditioned medium from CEACAM1-expressing cells induced endothelial cell apoptosis in vitro. Only medium conditioned by CEACAM1 mutants that were able to suppress tumor growth in vivo could cause endothelial cell apoptosis. These observations suggest that CEACAM1-mediated tumor suppression in vivo is, at least in part, due to the ability of CEACAM1 to inhibit tumor angiogenesis.