Genotyping of chimerical BCR-ABL1 RNA in chronic myeloid leukemia by integrated DNA chip.

Chronic myelogenous leukemia (CML) and Philadelphia chromosome-positive (Ph(+)) acute lymphoblastic leukemia (ALL) are associated with fusion of the BCR and ABL1 genes by chromosome translocation. The chimerical BCR-ABL1 gene encodes different fusion proteins that vary in size, depending on the breakpoint in the BCR region. Different types of fusion genes in CML and Ph(+) ALL are thought to be related to the clinical course and outcome of each patient. Currently, the genotypes are determined by PCR, followed by gel electrophoresis or DNA sequencing (among other methodologies). Our major aim was to develop a diagnostic method for CML genotyping by means of an integrated process of DNA microarray. Here, we describe a method of integrated multiplex reverse transcription, asymmetric PCR, and hybridization, all in the same reaction mixture in a chamber assembled on the surface of capture oligonucleotide probes immobilized on a glass slide. The integrated system successfully identified the four predominant types of chimerical BCR-ABL1 RNA (b3a2, b2a2, e1a2, and c3a2), which together account for 98% of CML cases. The integrated multiplex system also had a high sensitivity of detection (as little as 200 molecules of target RNA molecules). The integrated process saves time and effort, and it also the advantage of minimizing the steps needed for automated detection of different types of chimerical CML RNA.

Dramatic increase in the signal and sensitivity of detection via self-assembly of branched DNA.

In molecular testing using PCR, the target DNA is amplified via PCR and the sequence of interest is investigated via hybridization with short oligonucleotide capture probes that are either in a solution or immobilized on solid supports such as beads or glass slides. In this report, we report the discovery of assembly of DNA complex(es) between a capture probe and multiple strands of the PCR product. The DNA complex most likely has branched structure. The assembly of branched DNA was facilitated by the product of asymmetric PCR. The amount of branched DNA assembled was increased five fold when the asymmetric PCR product was denatured and hybridized with a capture probe all in the same PCR reaction mixture. The major branched DNA species appeared to contain three reverse strands (the strand complementary to the capture probe) and two forward strands. The DNA was sensitive to S1 nuclease suggesting that it had single-stranded gaps. Branched DNA also appeared to be assembled with the capture probes immobilized on the surface of solid support when the product of asymmetric PCR was hybridized. Assembly of the branched DNA was also increased when hybridization was performed in complete PCR reaction mixture suggesting the requirement of DNA synthesis. Integration of asymmetric PCR, heat denaturation and hybridization in the same PCR reaction mixture with the capture probes immobilized on the surface of solid support achieved dramatic increase in the signal and sensitivity of detection of DNA. Such a system should be advantageously applied for development of automated process for detection of DNA.

Suppression of neovascularization and experimental arthritis by D-form of anti-flt-1 peptide conjugated with mini-PEG(™).

Extensive angiogenesis in the synoviums is a characteristic pathology of rheumatoid arthritis (RA). We have demonstrated that anti-flt-1 hexapeptide, GNQWFI, specifically inhibits the interaction of VEGF or PlGF with its receptor flt-1 (Yoo et al. [13]). In this study, we investigate the feasibility of the synthetic D-form of anti-flt-1 hexapeptide conjugated with 8-amino-3,6-dioxaoctanoic acid (mini-PEG™) for treatment of RA. We first modified the structure of anti-flt-1 peptide from the L-form (GNQWFI) to all D-form (gnqwfi; allD) and then conjugated allD with mini-PEG™ to enhance its stability. The result showed that the allD anti-flt-1 peptide showed an increased stability in the sera without major loss of inhibitory activity. The allD and its mini-PEGylated derivative similarly suppressed wounding migration, chemotaxis, and tube formation of endothelial cells in vitro. However, in the Matrigels assay, the in vivo anti-angiogenic activity of mini-PEGylated allD was stronger than that of native allD or L-form. Moreover, oral and subcutaneous administration of mini-PEGylated allD, but not oral feeding of original L-form, successfully suppressed severity of collagen-induced arthritis. After a single subcutaneous injection, the Cy5-labeled mini-PEGylated allD was found to be distributed systemically and accumulated in arthritic joints of mice, particularly in joints with a severe clinical score. In conclusion, our data suggests that mini-PEGylated allD is more beneficial in the treatment of RA than unmodified anti-flt-1 peptides, since it has increased stability and the possibility of oral delivery, and could be applied to treat angiogenesis-dependent human diseases, including RA.

Dynamics of a heparin-binding domain of VEGF(165) complexed with its inhibitor triamterene.

Vascular endothelial growth factor (VEGF), which has neurotrophic and neuroprotective effects in addition to its major role in angiogenesis, interacts with Aß and accumulates in the senile plaques of Alzheimer's disease (AD) patients' brains. It is known that Aß binds to the heparin-binding domain (HBD) of the 165-amino acid VEGF variant, VEGF(165). In this study, we showed that triamterene (Trm) inhibits VEGF--Aß interaction without affecting other biological activities of VEGF or Aß. We investigated the importance of structural and dynamic features of HBD for its molecular-recognition processes. The binding model of HBD and Trm was constructed based on measurements of chemical shift changes and docking study. The results showed that the loop region (S11-L17) and F18 at the beginning of the first ß-sheet in the HBD constitute the inhibitor binding site. The N1 atom of pteridine ring of Trm forms hydrogen bonding with backbone amide proton of R13, and the phenyl ring took part in a hydrophobic interaction with the aromatic ring of F18. To investigate the functional importance of the inherent structural flexibility of the HBD in VEGF, the dynamic properties of free HBD and HBD--Trm complex were assessed by measuring spin relaxation rates, and the backbone dynamics were investigated by model-free analysis. The residues in the disordered loop region of the N-terminus exhibited conformational exchanges in free HBD, and flexibility of this loop region decreased dramatically upon binding to Trm, suggesting that Aß as well as inhibitor may recognize these unique dynamic features of the HBD. Furthermore, C-terminal residues continued to exhibit slow conformational motions, even in the HBD--Trm complex, implying that these motions at the C-terminus of the HBD might be important for interactions with heparin molecules. The flexibility of HBD demonstrated here should be essential for VEGF function and interaction with other protein partners.

A doubly signal-amplified DNA detection method based on pre-complexed [Ru(bpy)3]2+-doped silica nanoparticles.

Easy detection: The target DNA in a 10-100 aM range can be detected by pre-complexed nanoparticles without additional amplification or target labeling. The [Ru(bpy)(3)](2+)-doped silica nanoparticles are hybridized to form a complex with highly enhanced sensitivity (see scheme). This method will be a significant improvement over conventional microarray/fluorescence readout systems.

A serum-stable branched dimeric anti-VEGF peptide blocks tumor growth via anti-angiogenic activity.

Angiogenesis is critical and indispensable for tumor progression. Since VEGF is known to play a central role in angiogenesis, the disruption of VEGF-VEGF receptor system is a promising target for anti-cancer therapy. Previously, we reported that a hexapeptide (RRKRRR, RK6) blocked the growth and metastasis of tumor by inhibiting VEGF binding to its receptors. In addition, dRK6, the D-form derivative of RK6, retained its biological activity with improved serum stability. In the present study, we developed a serum-stable branched dimeric peptide (MAP2-dRK6) with enhanced anti-VEGF and anti-tumor activity. MAP2-dRK6 is more effective than dRK6 in many respects: inhibition of VEGF binding to its receptors, VEGF- and tumor conditioned medium-induced proliferation and ERK signaling of endothelial cells, and VEGF-induced migration and tube formation of endothelial cells. Moreover, MAP2-dRK6 blocks in vivo growth of VEGF-secreting colorectal cancer cells by the suppression of angiogenesis and the subsequent induction of tumor cell apoptosis. Our observations suggest that MAP2-dRK6 can be a prospective therapeutic molecule or lead compound for the development of drugs for various VEGF-related angiogenic diseases.

Anti-neuropilin-1 peptide inhibition of synoviocyte survival, angiogenesis, and experimental arthritis.

OBJECTIVE: To delineate the role of neuropilin-1 (NP-1), a vascular endothelial growth factor receptor (VEGFR), in rheumatoid inflammation and to determine whether blockade of NP-1 could suppress synoviocyte survival and angiogenesis. METHODS: VEGF(111-165) peptide, which encompasses the NP-1 binding domain of VEGF(165), was generated by cleaving VEGF(165) with plasmin. The effect of this peptide on the interaction between VEGF(165) and its receptor was determined by (125)I-VEGFR binding assay. Assays to determine synoviocyte apoptosis, adhesion, and migration were performed in the presence of VEGF(165) and/or the peptide. VEGF(165)-induced angiogenesis was assessed by measuring the proliferation, tube formation, and wounding migration of endothelial cells (ECs). Mice were immunized with type II collagen to induce experimental arthritis. RESULTS: VEGF(111-165) peptide specifically inhibited the binding of (125)I-VEGF(165) to NP-1 on rheumatoid synoviocytes and ECs. The peptide eliminated the VEGF(165)-mediated increase in synoviocyte survival and activation of p-ERK and Bcl-2. The peptide also completely inhibited a VEGF(165)-induced increase in synoviocyte adhesion and migration. In addition, the anti-NP-1 peptide blocked VEGF(165)-stimulated proliferation, capillary tube formation, and wounding migration of ECs in vitro. VEGF(165)-induced neovascularization in a Matrigel plug in mice was also blocked by treatment with the peptide. Finally, subcutaneous injection of anti-NP-1 peptide suppressed arthritis severity and autoantibody formation in mice with experimental arthritis and inhibited synoviocyte hyperplasia and angiogenesis in arthritic joints. CONCLUSION: Anti-NP-1 peptide suppressed VEGF(165)-induced increases in synoviocyte survival and angiogenesis, and thereby blocked experimental arthritis. Our findings suggest that anti-NP-1 peptide could be useful in alleviating chronic arthritis.

Dramatic increase in signal by integration of polymerase chain reaction and hybridization on surface of DNA microarray.

The cumbersome process required for diagnosis by DNA microarray can be simplified by simple extraction of nucleic acid from cells and by integration of liquid-phase polymerase chain reaction (PCR) and hybridization on the surface of a microarray slide. An unexpected benefit was the large (five- to sixfold) increase in detection signal that also is translated into an increase in sensitivity and the confidence level of diagnosis. The large increase in the detection signal appears to be due to participation of PCR primers as well as to extension of the immobilized capture probes during the hybridization process. The reason for the large increase in signal is not clear in view of only one round of DNA synthesis during the hybridization step. The integrated process correctly identified various genotypes of human papillomavirus (HPV) in the infected clinical human cervical specimens with specificity and efficiency. The process described in this article saves labor, time, and cost and should be applicable for automation of diagnosis by DNA microarray.

Vascular endothelial growth factor inhibition by dRK6 causes endothelial apoptosis, fibrosis, and inflammation in the heart via the Akt/eNOS axis in db/db mice.

OBJECTIVE: Vascular endothelial growth factor (VEGF), which is associated with the stimulation of angiogenesis and collateral vessel synthase, is one of the crucial factors involved in cardiac remodeling in type 2 diabetes. RESEARCH DESIGN AND METHODS: We investigated VEGF inhibition by dRK6 on the heart in an animal model of type 2 diabetes. Male db/db and db/m mice either were treated with dRK6 starting at 7 weeks of age for 12 weeks (db/db-dRK6 and db/m-dRK6) or were untreated. RESULTS: Cardiac dysfunction and hypertrophy were noted by echocardiogram and molecular markers in the db/db-dRK6 mice. The presence of diabetes significantly suppressed the expression of VEGF receptor (VEGFR)-1 and VEGFR-2, phospho-Akt, and phospho-endothelial nitric oxide synthase (eNOS) in the heart. In db/db-dRK6 mice, dRK6 completely inhibited VEGFR-2, phospho-Akt, and phospho-eNOS expression, whereas no effect on VEGFR-1 was observed. Cardiac fibrosis, microvascular scarcity associated with an increase in apoptotic endothelial cells, and inflammation were prominent, as well as increase in antiangiogenic growth factors. Cardiac 8-hydroxy-deoxyguanine and hypoxia-inducible factor-1alpha expression were significantly increased. No such changes were found in the other groups, including the db/m-dRK6 mice. The number of apoptotic human umbilical vein endothelial cells was increased by dRK6 in a dose-dependent manner only at high glucose concentrations, and this was associated with a decrease in phospho-Akt and phospho-eNOS related to oxidative stress. CONCLUSIONS: Our results demonstrated that systemic blockade of VEGF by dRK6 had deleterious effects on the heart in an animal model of type 2 diabetes; dRK6 induced downregulation of the VEGFR-2 and Akt-eNOS axis and enhancement of oxidative stress.

Interaction models of substrate peptides and beta-secretase studied by NMR spectroscopy and molecular dynamics simulation.

The formation of beta-amyloid peptide (Abeta) is initiated from cleavage of amyloid precursor protein (APP) by a family of protease, alpha-, beta-, and gamma-secretase. Sub W, a substrate peptide, consists of 10 amino acids, which are adjacent to the beta-cleavage site of wild-type APP, and Sub M is Swedish mutant with double mutations on the left side of the beta-cleavage site of APP. Sub W is a normal product of the metabolism of APP in the secretary pathway. Sub M is known to increase the efficiency of beta-secretase activity, resulting in a more specific binding model compared to Sub W. Three-dimensional structures of Sub W and Sub M were studied by CD and NMR spectroscopy in water solution. On the basis of these structures, interaction models of beta-secretase and substrate peptides were determined by molecular dynamics simulation. Four hydrogen bonds and one water-mediated interaction were formed in the docking models. In particular, the hydrogen bonding network of Sub M-BACE formed spread over the broad region of the active site of beta-secretase (P5-P3'), and the side chain of P2-Asn formed a hydrogen bond specifically with the side chain of Arg235. These are more favorable to the cleavage of Sub M by beta-secretase than Sub W. The two substrate peptides showed different tendency to bind to beta-secretase and this information may useful for drug development to treat and prevent Alzheimer's disease.

Role of placenta growth factor and its receptor flt-1 in rheumatoid inflammation: a link between angiogenesis and inflammation.

OBJECTIVE: To investigate the direct effects of placenta growth factor (PlGF) and its specific receptor, flt-1, which are known to mediate angiogenesis, on the inflammatory process of rheumatoid arthritis (RA). METHODS: Expression of PlGF and flt-1 in the synovial tissue of RA patients was examined using immunohistochemistry. Enzyme-linked immunosorbent assay was used to determine the concentrations of PlGF, tumor necrosis factor alpha (TNFalpha), and interleukin-6 (IL-6) in culture supernatants of either mononuclear cells or synoviocytes. The flt-1 expression level in mononuclear cells was analyzed by flow cytometry. Experimental arthritis was induced in mice either by immunization with type II collagen (CII) or by injection of anti-CII antibody. RESULTS: PlGF was highly expressed in the synovium of RA patients, and its primary source was fibroblast-like synoviocytes (FLS). When stimulated with IL-1beta, FLS from RA patients produced higher amounts of PlGF than did FLS from patients with osteoarthritis. Exogenous PlGF specifically increased the production of TNFalpha and IL-6 in mononuclear cells from RA patients (but not those from healthy controls) via a calcineurin-dependent pathway. The response to PlGF was associated with increased expression of flt-1 on RA monocytes, which could be induced by IL-1beta and TNFalpha. A novel anti-flt-1 hexapeptide, GNQWFI, abrogated the PlGF-induced increase in TNFalpha and IL-6 production, and also suppressed CII-induced arthritis and serum IL-6 concentrations in mice. Moreover, genetic ablation of PlGF prevented the development of anti-CII antibody-induced arthritis in mice. CONCLUSION: Our data suggest that enhanced expression of PlGF and flt-1 may contribute to rheumatoid inflammation by triggering production of proinflammatory cytokines. The use of the novel anti-flt-1 peptide, GNQWFI, may be an effective strategy for the treatment of RA.

Sphingosine-1-phosphate promotes lymphangiogenesis by stimulating S1P1/Gi/PLC/Ca2+ signaling pathways.

The lymphatic system plays pivotal roles in mediating tissue fluid homeostasis and immunity, and excessive lymphatic vessel formation is implicated in many pathological conditions, which include inflammation and tumor metastasis. However, the molecular mechanisms that regulate lymphatic vessel formation remain poorly characterized. Sphingosine-1-phosphate (S1P) is a potent bioactive lipid that is implicated in a variety of biologic processes such as inflammatory responses and angiogenesis. Here, we first report that S1P acts as a lymphangiogenic mediator. S1P induced migration, capillary-like tube formation, and intracellular Ca(2+) mobilization, but not proliferation, in human lymphatic endothelial cells (HLECs) in vitro. Moreover, a Matrigel plug assay demonstrated that S1P promoted the outgrowth of new lymphatic vessels in vivo. HLECs expressed S1P1 and S1P3, and both RNA interference-mediated down-regulation of S1P1 and an S1P1 antagonist significantly blocked S1P-mediated lymphangiogenesis. Furthermore, pertussis toxin, U73122, and BAPTA-AM efficiently blocked S1P-induced in vitro lymphangiogenesis and intracellular Ca(2+) mobilization of HLECs, indicating that S1P promotes lymphangiogenesis by stimulating S1P1/G(i)/phospholipase C/Ca(2+) signaling pathways. Our results suggest that S1P is the first lymphangiogenic bioactive lipid to be identified, and that S1P and its receptors might serve as new therapeutic targets against inflammatory diseases and lymphatic metastasis in tumors.

Toxic levels of amyloid beta peptide do not induce VEGF synthesis.

Alzheimer's disease is a neurodegenerative disorder associated with progressive loss of cognitive function and memory. Amyloid beta peptide (Abeta) is the major component of senile plaques and is known to exert its cytotoxic effect mainly by producing H2O2. Vascular endothelial growth factor (VEGF) is elevated in the cerebrospinal fluid (CSF) and brain of AD patients, and H2O2 is one of the factors that induce VEGF. Therefore, we tested whether Abeta might be responsible for the increased VEGF synthesis. We found that Abeta induced the production of H2O2 in vitro. Comparison of the amount of H2O2 required to induce VEGF synthesis in HN33 cells and the amount of H2O2 produced by 10 muM Abeta1-42 in vitro suggested that a toxic concentration of Abeta might induce VEGF synthesis in these cells. However, toxic concentrations of Abeta failed to induce VEGF synthesis in several cell systems. They also had no effect on antioxidant enzymes such as glutathione peroxidase, catalase, and peroxiredoxin in HN33 cells. Cu2+, Zn2+ and Fe3+ are known to accumulate in the brains of AD patients and promote aggregation of Abeta, and Cu2+ by itself induces synthesis of VEGF. However, there was no synergistic effect between Cu2+ and Abeta1-42 in the induction of VEGF synthesis and Zn2+ and Fe3+ also had no effect on the synthesis of VEGF, alone or in combination with Abeta.

Inhibition of amyloid beta-peptide production by blockage of beta-secretase cleavage site of amyloid precursor protein.

Amyloid beta-peptide (Abeta) is implicated as the major causative agent in Alzheimer's disease (AD). Abeta is produced by the processing of the amyloid precursor protein (APP) by BACE1 (beta-secretase) and gamma-secretase. Many inhibitors have been developed for the secretases. However, the inhibitors will interfere with the processing of not only APP but also of other secretase substrates. In this study, we describe the development of inhibitors that prevent production of Abeta by specific binding to the beta-cleavage site of APP. We used the hydropathic complementarity (HC) approach for the design of short peptide inhibitors. Some of the HC peptides were bound to the substrate peptide (Sub W) corresponding to the beta-cleavage site of APP and blocked its cleavage by recombinant human BACE1 (rhBACE1) in vitro. In addition, HC peptides specifically inhibited the cleavage of Sub W, and not affecting other BACE1 substrates. Chemical modification allowed an HC peptide (CIQIHF) to inhibit the processing of APP as well as the production of Abeta in the treated cells. Such novel APP-specific inhibitors will provide opportunity for the development of drugs that can be used for the prevention and treatment of AD with minimal side effects.

Interaction of vascular endothelial growth factor 165 with neuropilin-1 protects rheumatoid synoviocytes from apoptotic death by regulating Bcl-2 expression and Bax translocation.

Rheumatoid arthritis (RA) synoviocytes are resistant to apoptosis and exhibit a transformed phenotype, which might be caused by chronic exposure to genotoxic stimuli including reactive oxygen species and growth factors. In this study, we investigated the role of vascular endothelial growth factor165 (VEGF165), a potent angiogenic factor, and its receptor in the apoptosis of synoviocytes. We demonstrated here that neuropilin-1, rather than fms-like tyrosine kinase-1 and kinase insert domain-containing receptor, is the major VEGF165 receptor in the fibroblast-like synoviocytes. Neuropilin-1 was highly expressed in the lining layer, infiltrating leukocytes, and endothelial cells of rheumatoid synovium. The production of VEGF165, a ligand for neuropilin, was significantly higher in the RA synoviocytes than in the osteoarthritis synoviocytes. The ligation of recombinant VEGF165 to its receptor prevented the apoptosis of synoviocytes induced by serum starvation or sodium nitroprusside (SNP). VEGF165 rapidly triggered phospho-Akt and phospho-ERK activity and then induced Bcl-2 expression in the rheumatoid synoviocytes. The Akt or ERK inhibitor cancelled the protective effect of VEGF165 on SNP-induced synoviocyte apoptosis. Moreover, VEGF165 blocks SNP-induced Bcl-2 down-regulation as well as SNP-induced Bax translocation from the cytosol to the mitochondria. The down-regulation of the neuropilin-1 transcripts by short interfering RNA caused spontaneous synoviocyte apoptosis, which was associated with both the decrease in Bcl-2 expression and the increase in Bax translocation to mitochondria. Collectively, our data suggest that the interaction of VEGF165 with neuropilin-1 is crucial to the survival of rheumatoid synoviocytes and provide important implications for the abnormal growth of synoviocytes and therapeutic intervention in RA.

Potential lead for an Alzheimer drug: a peptide that blocks intermolecular interaction and amyloid beta protein-induced cytotoxicity.

A peptide chAbeta30-16 (15-mer; CTFVRTHIFCKEHQF) was designed to bind to a region encompassing the entire polymerization-related (16KLVFF20) and part of the polymerization and toxicity-related (25GSNKGAIIGLM35) regions of amyloid beta-protein, Abeta1-42 by a hydropathic complementary approach. This peptide efficiently binds to Abeta and blocks intermolecular interaction and the formation of Abeta aggregates. In addition, the peptide neutralizes the cell toxicity of Abeta fibrils. The chAbeta30-16 peptide or its derivatives may be a starting point for the future development of drugs that prevent the neurotoxicity and deposition of Abeta in the brain of Alzheimer's disease.

Anti-flt1 peptide, a vascular endothelial growth factor receptor 1-specific hexapeptide, inhibits tumor growth and metastasis.

PURPOSE: The purpose of this study was to develop antagonists specific for the vascular endothelial growth factor receptor 1 (VEGFR1) and to investigate the effects of the antagonists on the VEGF-induced endothelial cell functions and tumor progression. EXPERIMENTAL DESIGN: Hexapeptides that inhibit binding of VEGFR1 and VEGF were identified through screening of synthetic peptide library. A selected peptide, anti-Flt1, was investigated for binding specificity with various receptors and ligand peptides. Effects of the peptide on proliferation, cell migration, and fibrin gel-based angiogenesis of endothelial cells were also investigated. The activity of anti-Flt1, in vivo, was evaluated for inhibition of tumor growth and metastasis in VEGF-secreting cancer cell-implanted mice by s.c. injections of the peptide. RESULTS: Here, we report on a short peptide that binds to VEGFR1 and prevents binding of VEGF. A hexapeptide, anti-Flt1 (Gly-Asn-Gln-Trp-Phe-Ile or GNQWFI), was identified from peptide libraries. The anti-Flt1 peptide shows specificity toward binding to VEGFR1 and it inhibits binding of VEGF, placental growth factor (PlGF), and VEGF/PlGF heterodimer to VEGFR1. This peptide does not inhibit the proliferation of endothelial cells induced by VEGF and VEGF/PlGF heterodimer but it effectively blocks VEGF-induced migration of endothelial cells and their capacity to form capillary-like structures on fibrin gel-based in vitro angiogenesis system. Furthermore, growth and metastasis of VEGF-secreting tumor cells were also significantly inhibited by s.c. injections of anti-Flt1 peptide in nude mice. Accordingly, VEGF-induced migration and capillary formation are mediated through VEGFR1, and these processes may play an important role in the growth and metastasis of VEGF-secreting tumors. CONCLUSIONS: We show that a peptide (anti-Flt1) specific for VEGFR1 inhibits growth and metastasis of tumor that secretes VEGF. The effects on endothelial cell functions, in vitro, indicate that the anticancer activity of anti-Flt1 peptide with reduced blood vessel density could also be due to the blocking of VEGFR1-mediated endothelial cell migration and tube formation. Although the effects of anti-Flt1 peptide still remain to be further characterized, the receptor 1-specific peptide antagonist, anti-Flt1, has potential as a therapeutic agent for various angiogenesis-related diseases, especially cancer.

Arginine-rich anti-vascular endothelial growth factor (anti-VEGF) hexapeptide inhibits collagen-induced arthritis and VEGF-stimulated productions of TNF-alpha and IL-6 by human monocytes.

Vascular endothelial growth factor (VEGF) has been suggested to play a critical role in the pathogenesis of rheumatoid arthritis (RA). We previously identified a novel RRKRRR hexapeptide that blocked the interaction between VEGF and its receptor through the screening of peptide libraries. In this study, we investigated whether anti-VEGF peptide RRKRRR (dRK6) could suppress collagen-induced arthritis (CIA) and regulate the activation of mononuclear cells of RA patients. A s.c. injection of dRK6 resulted in a dose-dependent decrease in the severity and incidence of CIA and suppressed synovial infiltration of inflammatory cells in DBA/1 mice. In these mice, the T cell responses to type II collagen (CII) in lymph node cells and circulating IgG Abs to CII were also dose-dependently inhibited by the peptides. In addition, VEGF directly increased the production of TNF-alpha and IL-6 from human PBMC. Synovial fluid mononuclear cells of RA patients showed a greater response to VEGF stimulation than the PBMC of healthy controls. The major cell types responding to VEGF were monocytes. Moreover, anti-VEGF dRK6 inhibited the VEGF-induced production of TNF-alpha and IL-6 from synovial fluid mononuclear cells of RA patients and decreased serum IL-6 levels in CIA mice. In summary, we observed first that dRK6 suppressed the ongoing paw inflammation in mice and blocked the VEGF-induced production of proinflammatory cytokines. These data suggest that dRK6 may be an effective strategy in the treatment of RA, and could be applied to modulate various chronic VEGF-dependent inflammatory diseases.

Specific interaction of VEGF165 with beta-amyloid, and its protective effect on beta-amyloid-induced neurotoxicity.

beta-amyloid (Abeta) is a major component of senile plaques that is commonly found in the brain of Alzheimer's disease (AD) patient. In the previous report, we showed that an important angiogenic factor, vascular endothelial growth factor (VEGF) interacts with Abeta and is accumulated in the senile plaques of AD patients' brains. Here we show that Abeta interacts with VEGF(165) isoform, but not with VEGF(121). Abeta binds to the heparin-binding domain (HBD) of VEGF(165) with similar affinity as that of intact VEGF(165). Abeta binds mostly to the C-terminal subdomain of HBD, but with greatly reduced affinity than HBD. Therefore, the full length of HBD appears to be required for maximal binding of Abeta. Although Abeta binds to heparin-binding sequence of VEGF, it does not bind to other heparin-binding growth factors except midkine. Thus it seems that Abeta recognizes unique structural features of VEGF HBD. VEGF(165) prevents aggregation of Abeta through its HBD. We localized the core VEGF binding site of Abeta at around 26-35 region of the peptide. VEGF(165) and HBD protect PC12 cells from the Abeta-induced cytotoxicity. The mechanism of protection appears to be inhibition of both Abeta-induced formation of reactive oxygen species and Abeta aggregation.

Co-accumulation of vascular endothelial growth factor with beta-amyloid in the brain of patients with Alzheimer's disease.

Alzheimer's disease (AD) is accompanied by the progressive deposition of beta-amyloid (Abeta) in both senile plaques and cerebral blood vessels, loss of central neurons, and vessel damage. Cerebral hypoperfusion is one of the major clinical features in AD and likely plays a critical role in its pathogenesis. In addition to its major roles in angiogenesis, vascular endothelial growth factor (VEGF) has neurotrophic and neuroprotective effects. VEGF is an ischemia-inducible factor and increased expression of VEGF often occurs in AD. Although the presence of VEGF immunoreactivity in the AD brain has been described previously, the direct interaction of VEGF with Abeta has not been established. Here, we show that VEGF is co-localized with Abeta plaques in the brains of patients with AD. In vitro experiments show that VEGF binds to Abeta with high affinity (K(D) approximate to 50 pM). VEGF is co-aggregated with Abeta without any apparent effect on the rate of aggregation, strongly binds to pre-aggregated Abeta, and is very slowly released from the co-aggregated complex. Continuous deposition of VEGF in the amyloid plaques most likely results in deficiency of available VEGF under hypoperfusion and, thus, may contribute to neurodegeneration and vascular dysfunction in the progression of AD.