Triazolopeptides Inhibiting the Interaction between Neuropilin-1 and Vascular Endothelial Growth Factor-165.

Inhibiting the interaction of neuropilin-1 (NRP-1) with vascular endothelial growth factor (VEGF) has become an interesting mechanism for potential anticancer therapies. In our previous works, we have obtained several submicromolar inhibitors of this interaction, including branched pentapeptides of general structure Lys(Har)-Xxx-Xxx-Arg. With the intent to improve the proteolytic stability of our inhibitors, we turned our attention to 1,4-disubstituted 1,2,3-triazoles as peptide bond isosteres. In the present contribution, we report the synthesis of 23 novel triazolopeptides along with their inhibitory activity. The compounds were synthesized using typical peptide chemistry methods, but with a conversion of amine into azide completely on solid support. The inhibitory activity of the synthesized derivatives spans from 9.2% to 58.1% at 10 µM concentration (the best compound Lys(Har)-GlyΨ[Trl]GlyΨ[Trl]Arg, 3, IC50 = 8.39 µM). Synthesized peptidotriazoles were tested for stability in human plasma and showed remarkable resistance toward proteolysis, with half-life times far exceeding 48 h. In vitro cell survival test resulted in no significant impact on bone marrow derived murine cells 32D viability. By means of molecular dynamics, we were able to propose a binding mode for compound 3 and discuss the observed structure-activity relationships.

Branched pentapeptides as potent inhibitors of the vascular endothelial growth factor 165 binding to Neuropilin-1: Design, synthesis and biological activity.

The demonstrated involvement of VEGF165/NRP-1 complex in pathological angiogenesis has catalyzed interest in blocking this interaction to combat angiogenesis dependent diseases. It was shown before that Lys-Pro-Pro-Arg is a fairly strong inhibitor of the VEGF165/NRP-1 interaction. Our current findings suggest that the side chain elongation of the Lys1 by branching it with additional homoarginine (Har) residue, to obtain Lys(Har)-Pro-Pro-Arg, allows more effective inhibition. Moreover, increasing the flexibility of the middle part of molecule, in particular with simultaneous introduction of additional interacting elements at the second or third position, produced compounds up to 30-fold more active (IC50 = 0.2 µM) than the heptapeptide ATWLPPR (A7R) which is one of the first peptide known as an effective antagonist of the VEGF165 binding to NRP-1 and in vivo decreases breast cancer angiogenesis and growth. Herein, we present also the structure-activity study of Lys(Har)-Pro-Pro-Arg, discussing the design, synthesis, inhibitory activity, proteolytic stability and molecular modeling of the prepared derivatives. For two of the most active analogs the high proteolytic stability was also observed. These studies provide the next step for elucidating the optimal structure of the small peptidic inhibitors of VEGF165/NRP-1 interaction that could serve as research tools or be prospective drug candidates.

Structure-activity relationship study of tetrapeptide inhibitors of the Vascular Endothelial Growth Factor A binding to Neuropilin-1.

Neuropilin-1 is considered as one of the key receptors responsible for signaling pathways involved in pathological angiogenesis necessary for tumor progression, therefore targeting of VEGF165 binding to NRP-1 could be a relevant strategy for antiangiogenic treatment. It was shown before that the VEGF165/NRP-1 interaction can be inhibited by short tetrapeptides with K/RXXR sequence. Here, we present a structure-activity relationship study of the systematic optimization of amino acid residues in positions 1-3 in the above tetrapeptides. All the 13 synthesized analogs possessed C-terminal arginine that is a necessary element for interaction with NRP-1. The obtained results of the inhibitory activity and modeling by molecular dynamics indicate that simultaneous interactions of the basic amino acid residues in position 1 and 4 (Arg) with Neuropilin-1 are crucial and their cooperation strongly affects the inhibitory activity. In addition, the binding strength is modulated by the flexibility of the peptide backbone (in the central part of the peptide), and the nature of the side chain of the amino acids at the second or third position. A dramatic decrease in the activity to the receptor is observed in flexible derivatives that are missing proline residues. The results described in this paper should prove useful for future studies aimed at establishing the best pharmacophore for inhibitors of VEGF165 binding to NRP-1.

Conformational latitude - activity relationship of KPPR tetrapeptide analogues toward their ability to inhibit binding of vascular endothelial growth factor 165 to neuropilin-1.

Neuropilin-1 has been found to be overexpressed in several kinds of malignant tumors, and it is postulated that its interaction with the vascular endothelial growth factor 165 leads to progression of tumor vascularization and growth. Several analogues (KxxR) with various conformational latitudes have been synthesized and found as inhibitors of NRP-1. Detailed insight provided by molecular dynamics simulation allowed forming a clear relationship between flexibility of xx part of the molecule and its inhibitory activity.

Physicochemical properties and in vitro cytotoxicity of iron oxide-based nanoparticles modified with antiangiogenic and antitumor peptide A7R.

Superparamagnetic iron oxide-based nanoparticles (SPIONs) are promising carriers as targeted drug delivery vehicles, because they can be guided to their target with the help of an external magnetic field. Functionalization of nanoparticles' surface with molecules, which bind with high affinity to receptors on target tissue significantly facilitates delivery of coated nanoparticles to their targeted site. Here, we demonstrate conjugation of an antiangiogenic and antitumor peptide ATWLPPR (A7R) to SPIONs modified with sebacic acid (SPIONs-SA). Successful conjugation was confirmed by various analytical techniques (FTIR, SERS, SEM-EDS, TEM, TGA). Cell cytotoxicity studies, against two cell lines (HUVEC and MDA-MB-231) indicated that SPIONs modified with A7R reduced HUVEC cell viability at concentrations higher than 0.01 mg Fe/mL, in comparison to cells that were exposed to either the nanoparticles modified with sebacic acid or A7R peptide solely, what might be partially caused by a process of internalization.

Structure-activity relationship study of a small cyclic peptide H-c[Lys-Pro-Glu]-Arg-OH: a potent inhibitor of Vascular Endothelial Growth Factor interaction with Neuropilin-1.

Inhibition of angiogenesis is one of the most promising approaches in anticancer therapy. It was recently suggested that Neuropilin-1 (NRP-1) in tumour cells may serve as a separate receptor for Vascular Endothelial Growth Factor-165 (VEGF165) which is one of the main pro-angiogenic agents in the organism. Therefore molecules inhibiting VEGF165 binding to NRP-1 could be potential candidates for new antiangiogenic and anticancer drugs. Here we present a structure-activity relationship study of the peptide H-c[Lys-Pro-Glu]-Arg-OH which showed high inhibitory effect on VEGF165/NRP-1 binding (IC50=0.18µM) in our previous study. We report the design, synthesis, in vitro assays and docking analysis of four small cyclic peptides (14-,15-membered ring) and one bigger cyclic compound (30-membered ring). Our study shows that both the ring size and configuration of amino acid residues present in the structure are crucial for high inhibitory effect.

Discovery of novel inhibitors of vascular endothelial growth factor-A-Neuropilin-1 interaction by structure-based virtual screening.

Neuropilin-1 (NRP-1), one of the most important co-receptors of vascular endothelial growth factor-A (VEGF-A), increases its angiogenic action in several chronic diseases including cancer by increasing the activity of associated tyrosine kinase receptors, VEGFR1 and VEGFR2. Binding of VEGF-A to NRP-1 plays a critical role in pathological angiogenesis and tumor progression. Today, targeting this interaction is a validated approach to fight against angiogenesis-dependent diseases. Only anti-NRP-1 antibodies, peptide and peptidomimetic drug-candidates or hits have been developed thus far. In order to identify potent orally active small organic molecules various experimental and in silico approaches can be used. Here we report, novel promising small drug-like molecules disrupting the binding of VEGF-A165 to NRP-1. We carried out structure-based virtual screening experiments using the ChemBridge compound collection on the VEGF-A165 binding pocket of NRP-1. After docking and two rounds of similarity search computations, we identified 4 compounds that inhibit the biotinylated VEGF-A165 binding to recombinant NRP-1 with Ki of about 10 µM. These compounds contain a common chlorobenzyloxy alkyloxy halogenobenzyl amine scaffold that can serve as a base for further development of new NRP-1 inhibitors.

Transcriptome analysis and in vivo activity of fluvastatin versus zoledronic acid in a murine breast cancer metastasis model.

Statins and bisphosphonates are two distinct classes of isoprenoid pathway inhibitors targeting downstream enzyme to HMG-CoA reductase (upstream enzyme) and farnesyl-pyrophosphate synthase, respectively. Here, we studied fluvastatin (Fluva) and zoledronate (Zol), representative molecules of each class, respectively. In vivo metastatic potentials of both molecules were assessed. For the first time, we observed a significant reduction in progression of established metastases with Fluva treatment. Treatment with both Zol at 100 µg/kg and Fluva at 15 mg/kg inhibited 80% of the metastasis bioluminescence signal and increased survival of mice. The Zol and Fluva transcriptomic profiles of treated MDA-MB-231 cells revealed analogous patterns of affected genes, but each of them reached with different kinetics. The observable changes in gene expression started after 24 h for Fluva IC(50 72 h) and only after 48 h for Zol IC(50 72 h). To obtain early changes in gene expression of Zol-treated cells, a 3 times higher dose of Zol IC(50 72 h) had to be applied. Combining Fluva and Zol in vivo showed no synergy, but a benefit of several days in survival of mice. This study demonstrated that Zol or Fluva is of potential clinical use for the treatment of established metastasis.

Overexpression of VEGF189 in breast cancer cells induces apoptosis via NRP1 under stress conditions.

The existence of multiple VEGF-A isoforms raised the possibility that they may have distinct functions in tumor growth. We have previously published that VEGF189 and VEGF165 contribute to breast cancer progression and angiogenesis, but VEGF165 induced the most rapid tumor uptake. Since VEGF165 has been described as a survival factor for breast tumor cells, we questioned here the effects of VEGF189 on the survival/apoptosis of MDA-MB-231 cells. We used clones which overexpress VEGF189 (V189) or VEGF165 (V165) isoforms and compared them to a control one (cV). Overexpression of VEGF189 resulted in increased cell apoptosis, as determined by Annexin-V apoptosis assay, under serum starvation and doxorubicin treatment, while VEGF 165 was confirmed to be a survival factor. Since MDA-MB-231 highly express NRP1 (a co-receptor for VEGF-A), we used short hairpin RNA (shRNA) to knockdown NRP1 expression. V189shNRP1 clones were characterized by reduced apoptosis and higher necrosis, as compared to V189shCtl, under stress conditions. Unexpectedly, NRP1 knock-down had no effect on the survival or apoptosis of V165 cells. VEGF189 showed greater affinity towards NRP1 than VEGF165 using a BIAcore binding assay. Finally, since endogenously produced urokinase-type plasminogen (uPA) has been found to prevent apoptosis in breast cancers, we analyzed the level of uPA activity in our clones. An inhibition of uPA activity was observed in V189shNRP1 clones. Altogether, these results suggest a major role of NRP1 in apoptosis induced by VEGF189 in stress conditions and confirm VEGF165 as a survival factor.

Invading basement membrane matrix is sufficient for MDA-MB-231 breast cancer cells to develop a stable in vivo metastatic phenotype.

INTRODUCTION: The poor efficacy of various anti-cancer treatments against metastatic cells has focused attention on the role of tumor microenvironment in cancer progression. To understand the contribution of the extracellular matrix (ECM) environment to this phenomenon, we isolated ECM surrogate invading cell populations from MDA-MB-231 breast cancer cells and studied their genotype and malignant phenotype. METHODS: We isolated invasive subpopulations (INV) from non invasive populations (REF) using a 2D-Matrigel assay, a surrogate of basal membrane passage. INV and REF populations were investigated by microarray assay and for their capacities to adhere, invade and transmigrate in vitro, and to form metastases in nude mice. RESULTS: REF and INV subpopulations were stable in culture and present different transcriptome profiles. INV cells were characterized by reduced expression of cell adhesion and cell-cell junction genes (44% of down regulated genes) and by a gain in expression of anti-apoptotic and pro-angiogenic gene sets. In line with this observation, in vitro INV cells showed reduced adhesion and increased motility through endothelial monolayers and fibronectin. When injected into the circulation, INV cells induced metastases formation, and reduced injected mice survival by up to 80% as compared to REF cells. In nude mice, INV xenografts grew rapidly inducing vessel formation and displaying resistance to apoptosis. CONCLUSION: Our findings reveal that the in vitro ECM microenvironment per se was sufficient to select for tumor cells with a stable metastatic phenotype in vivo characterized by loss of adhesion molecules expression and induction of pro-angiogenic and survival factors.

An anticancer strategic dilemma: to kill or to contain. The choice of the pharmaceutical industry in 2009.

For decades, the fight against cancer was based on oncolytic drugs aimed at eradicating malignant cells (killing strategy). The main flaws of this approach were its toxicity and the consequent emergence of resistance. New views on tumour biology consider tumours as complex organs involving dynamic interactions between their components. This implies the existence of dormant states and thus of a new therapeutic strategy aimed at inducing or extending tumour dormancy (containment strategy). The aim of this overview was to quantify the relative importance of these two strategies among the clinical trials (240 phase 1 and 186 phase 2 trials), launched or still in the pipeline and sponsored by the pharmaceutical industry in 2009. The most frequently targeted molecular entities are vascular endothelial growth factors (VEGFRs) (19 drugs), ErBBs (17 drugs), c-met (14 drugs), tubulin (12 drugs), IGFRs (12 drugs). The main result of this overview is that the killing strategy is still largely prevailing since 326 drugs in 2009 (77% of the drugs tested in clinical trials in 2009) referred to this strategy, whereas 100 drugs could be attributed to the containment or mixed strategies in 2009. To obtain a dynamic view of the repartition of drugs between the killing strategy and the containment or mixed strategies, the present work should be renewed every 3-4 years.

Does delaying adjuvant chemotherapy after curative surgery for colorectal cancer impair survival? A meta-analysis.

BACKGROUND: In stage III colorectal cancer (CRC), adjuvant chemotherapy (CT) is usually prescribed within two months after curative surgery. Whether or not delaying initiation of CT affects survival is still debated. MATERIAL AND METHODS: We performed a meta-analysis (MA) of all published studies (full papers or abstracts) comparing delayed CT with standard care. Studies were obtained from a PubMed query (keywords: CRC, adjuvant treatment, delay of CT), a review (Chau et al., 2006), cross-checking references and abstracts from the proceedings of ASCO, ASCO GI and WCGI annual meetings. We chose a cutoff delay of 8 weeks. Risk Ratios (RRs) were calculated from the recorded events (deaths, relapses). We used EasyMA software (fixed-effect model). RESULTS: Fourteen studies (including four abstracts) were identified (17,645 patients; 5,952 males, 5,151 females, mean age 70 years). Of these, three could not be statistically analysed and three used another cutoff (4, 5 or 6 weeks), leaving 8 studies for main MA (13,158 patients; 3,932 males, 3,644 females, 5,942 missing data; 5,576 colon cancers, 6,677 rectal, 1,265 missing data). Delaying CT more than 8 weeks was associated to worse Overall Survival (OS) (RR: 1.20; 95% Confidence Interval (CI) 1.15-1.26). In the MA including all studies whatever their cutoff, longer delay was similarly associated to a worse OS but not a worse Relapse-Free Survival (RFS) (five studies). CONCLUSION: Adjuvant chemotherapy should be started within 8 weeks after surgery. Delaying the initiation of adjuvant CT for more than 8 weeks after surgery significantly decreased OS but not RFS. This discrepancy might be due to factors not directly related to cancer (post-operative complications, social status) or to a more accurate appraisal of death.

Duration of adjuvant chemotherapy for patients with non-metastatic colorectal cancer.

BACKGROUND: Surgery of primary tumour is the backbone of colorectal cancer treatment (CRC). But in stage III cancer, metastatic or local relapse is often observed (50%). So, adjuvant treatment is always considered in this setting. The best treatment duration of hypothetic disease is not easy to define. Adjuvant chemotherapy for CRC actually lasts 6 months. The choice of optimal duration is based upon old studies using 5-fluorouracil (5FU). During the last ten years, results of major randomized controlled studies (RCTs) comparing different durations of treatments and different schedules in adjuvant setting were published. Several studies compared a 6-month chemotherapy with a longer treatment. Conversely, a single study by Chau et al compared a 6 month chemotherapy with continuous treatment lasting 3 months. But the optimal duration of these chemotherapies could be challenged. Even though the optimal duration of chemotherapy in CRC is a major issue, it has never been answered adequately. OBJECTIVES: To evaluate the optimal duration of adjuvant treatment, we performed a meta-analysis of all RCTs comparing two durations of adjuvant treatment, 6 months versus 9 to 12 months. SEARCH STRATEGY: Publications were identified from PubMed (February 28th, 2009), Embase, and the Cochrane Database of Clinical Controlled Trials (CENTRAL) in the Cochrane Library 2009 issue 1. Reviews and books were also scrutinized. Abstracts were reviewed from ASCO annual meetings proceedings from 1998 to 2009. SELECTION CRITERIA: Patients with surgically resected colorectal cancer with high risk of recurrence. DATA COLLECTION AND ANALYSIS: Several RCTs compared shorter versus longer durations of chemotherapy, 6 studies for overall survival (OS) and 7 studies for relapse free survival (RFS), for a total of 10326 patients, mean age 63.1 years, including 9826 colon and 500 rectum cancers. MAIN RESULTS: Treatments were always based on 5-FU. Two studies were excluded, an epidemiological study and a study comparing continuous treatment during 3 months with conventional chemotherapy during 6 months. The later because it compared 2 durations less than or equal to 6 months. Shorter duration of chemotherapy (3-6 months) compared with longer duration (9-12 months) was not associated to poorer RFS (RR =0.96, 95% CI : 0.90-1.02) and OS (RR = 0.96 ; 95% CI : 0.91-1.02). AUTHORS' CONCLUSIONS: The present meta-analysis confirmed that adjuvant chemotherapy of CRC should not last for more than 6 months. Prolonged duration would result in lower benefit to risk ratio. However, the results do not make it possible to favour either 3 or 6 month durations. They should help design a future RCT comparing different durations of continuous treatment.

Glycosaminoglycan mimetics inhibit SDF-1/CXCL12-mediated migration and invasion of human hepatoma cells.

We have recently reported that the CXC-chemokine stromal cell-derived factor-1 (SDF-1)/CXCL12 induces proliferation, migration, and invasion of the Huh7 human hepatoma cells through its G-protein-coupled receptor CXCR4 and that glycosaminoglycans (GAGs) are involved in these events. Here, we demonstrate by surface plasmon resonance that the chemokine binds to GAG mimetics obtained by grafting carboxylate, sulfate or acetate groups onto a dextran backbone. We also demonstrate that chemically modified dextrans inhibit SDF-1/CXCL12-mediated in vitro chemotaxis and anchorage-independent cell growth in a dose-dependent manner. The binding of GAG mimetics to the chemokine and their effects in modulating the SDF-1/CXCL12 biological activities are mainly related to the presence of sulfate groups. Furthermore, the mRNA expression of enzymes involved in heparan sulfate biosynthesis, such as exostosin-1 and -2 or N-deacetylase N-sulfotransferases remained unchanged, but heparanase mRNA and protein expressions in Huh7 cells were decreased upon GAG mimetic treatment. Moreover, decreasing heparanase-1 mRNA levels by RNA interference significantly reduced SDF-1/CXCL12-induced extracellular signal-regulated kinase 1/2 (ERK 1/2) phosphorylation. Therefore, we suggest that GAG mimetic effects on SDF-1/CXCL12-mediated hepatoma cell chemotaxis may rely on decreased heparanase expression, which impairs SDF-1/CXCL12's signaling. Altogether, these data suggest that GAG mimetics may compete with cellular heparan sulfate chains for the binding to SDF-1/CXCL12 and may affect heparanase expression, leading to reduced SDF-1/CXCL12 mediated in vitro chemotaxis and growth of hepatoma cells.

Does microsatellite instability predict the efficacy of adjuvant chemotherapy in colorectal cancer? A systematic review with meta-analysis.

BACKGROUND: Microsatellite instability (MSI) status in predicting the efficacy of adjuvant chemotherapy in colorectal cancer remains controversial. MATERIALS AND METHODS: Studies were identified through PubMed, Embase and ASCO proceedings with a combination of keywords (colorectal cancer, chemotherapy and MSI). RESULTS: A MA was performed for treated and non-treated MSI population on seven studies. Statistical calculations were performed on 7 studies representing 3690 patients; mean age: 65.5 years; 810 stage II and 2444 stage III (75%). MSI-high (MSI-H) was found in 454 patients (14% of the global population), and microsatellite stable (MSS) in 2871. A total of 1444 patients received 5-fluorouracil (5FU)-based chemotherapy, whereas 1518 patients did not. For MSI-H patients, there was no statistically significant difference for RFS whether or not they received chemotherapy (5 studies); HR RFS: 0.96 (95% confidence interval (CI): 0.62-1.49); HR OS (6 studies): 0.70 (95% CI: 0.44-1.09; p=0.12). Elsewhere, we found a significant interaction between MSI status (MSI-H or MSS) and therapeutic status suggesting a lesser benefit for MSI-H than for MSS patients (HR interaction RFS: 0.77 (95% CI: 0.67-0.87)). CONCLUSION: We found similar RFS for treated and untreated MSI-H patients, showing that MSI-H status, in addition to being a good prognostic factor is also a predictive factor of non response.

Microsatellite instability does not predict the efficacy of chemotherapy in metastatic colorectal cancer. A systematic review and meta-analysis.

BACKGROUND: Microsatellite Instability (MSI) status is a good prognostic factor for colorectal cancer (CRC) but its predictive value for chemosensitivity remains controversial. A previous meta-analysis (MA) in the adjuvant setting showed that MSI-high (H) status did not predict the efficacy of chemotherapy. The predictive value of MSI status on the effect of metastatic chemotherapy was investigated by MA. PATIENTS AND METHODS: Studies were identified by electronic search through PubMed, Embase and ASCO proceedings online databases, using several key words (colorectal cancer, chemotherapy, microsatellite instability). For each study, the ratio of response rate (RR), complete (CR) and partial response (PR) divided by stable disease and progression was calculated. From 190 articles and 100 abstracts, only eight independent studies were selected. The data were analysed with a random-effect model (due to heterogeneity between studies) using EasyMA software. Statistical calculations were performed on six studies representing 964 patients (mean age 63 years; 91 MSI-H; 873 microsatellite stable (MSS) tumours). A total of 287 patients received 5-fluorouracil (5FU)-based chemotherapy, whereas 678 patients received combinations of 5FU or capecitabine with oxaliplatin and/or irinotecan. RESULTS: No benefit of metastatic chemotherapy in terms of RR for MSI-H patients compared with MSS patients was found. The global hazard ratio (HR) for RR was 0.82 (95% confidence interval, CI: 0.95; 0.65-1.03; p=0.09). CONCLUSION: MSI status does not predict the effect of chemotherapy which is similar in MSI-H and MSS metastatic CRC tumours.

New symmetrically esterified m-bromobenzyl non-aminobisphosphonates inhibited breast cancer growth and metastases.

BACKGROUND: Although there was growing evidence in the potential use of Bisphosphonates (BPs) in cancer therapy, their strong osseous affinities that contrast their poor soft tissue uptake limited their use. Here, we developed a new strategy to overcome BPs hydrophilicity by masking the phosphonic acid through organic protecting groups and introducing hydrophobic functions in the side chain. METHODOLOGY/PRINCIPAL FINDINGS: We synthesized non-nitrogen BPs (non N-BPs) containing bromobenzyl group (BP7033Br) in their side chain that were symmetrically esterified with hydrophobic 4-methoxphenyl (BP7033BrALK) and assessed their effects on breast cancer estrogen-responsive cells (T47D, MCF-7) as well as on non responsive ones (SKBR3, MDA-MB-231 and its highly metastatic derived D3H2LN subclone). BP7033Br ALK was more efficient in inhibiting tumor cell proliferation, migration and survival when compared to BP7033Br. Although both compounds inhibited tumor growth without side effects, only BP7033Br ALK abrogated tumor angiogenesis and D3H2LN cells-induced metastases formation. CONCLUSION/SIGNIFICANCE: Taken together these data suggest the potential therapeutic use of this new class of esterified Bisphosphonates (BPs) in the treatment of tumor progression and metastasis without toxic adverse effects.

HTLV-1 uses HSPG and neuropilin-1 for entry by molecular mimicry of VEGF165.

Human T-cell lymphotropic virus type 1 (HTLV-1) entry involves the interaction between the surface (SU) subunit of the Env proteins and cellular receptor(s). Previously, our laboratories demonstrated that heparan sulfate proteoglycans (HSPGs) and neuropilin-1 (NRP-1), a receptor of VEGF(165), are essential for HTLV-1 entry. Here we investigated whether, as when binding VEGF(165), HSPGs and NRP-1 work in concert during HTLV-1 entry. VEGF(165) binds to the b domain of NRP-1 through both HSPG-dependent and -independent interactions, the latter involving its exon 8. We show that VEGF(165) is a selective competitor of HTLV-1 entry and that HTLV-1 mimics VEGF(165) to recruit HSPGs and NRP-1: (1) the NRP-1 b domain is required for HTLV-1 binding; (2) SU binding to target cells is blocked by the HSPG-binding domain of VEGF(165); (3) the formation of Env/NRP-1 complexes is enhanced by HSPGs; and (4) the HTLV SU contains a motif homologous to VEGF(165) exon 8. This motif directly binds to NRP-1 and is essential for HTLV-1 binding to, internalization into, and infection of CD4(+) T cells and dendritic cells. These findings demonstrate that HSPGs and NRP-1 function as HTLV-1 receptors in a cooperative manner and reveal an unexpected mimicry mechanism that may have major implications in vivo.

Factitious increases in serum testosterone concentrations related to phenylbutazone therapy.

We report 6 additional observations of a drug/hormone assay interaction between serum testosterone and phenylbutazone intake. This interaction had been described previously only once. We discuss its potential mechanisms, based upon our experimental findings, and its clinical implications.

Distinct heparin binding sites on VEGF165 and its receptors revealed by their interaction with a non sulfated glycoaminoglycan (NaPaC).

We previously demonstrated that a non sulfated analogue of heparin, phenylacetate carboxymethyl benzylamide dextran (NaPaC) inhibited angiogenesis. Here, we observed that NaPaC inhibited the VEGF165 binding to both VEGFR2 and NRP-1 and abolished VEGFR2 activity. Further, we explored the effects of NaPaC on VEGF165 interactions with its receptors, VEGFR2 and NRP-1, co-receptor of VEGFR2. Surface plasmon resonance and affinity gel electrophoresis showed that NaPaC interacted directly with VEGF165, VEGFR2 and NRP-1 but not with heparin-independent factor such as VEGF121. NaPaC completely inhibited the heparin binding to VEGF165, NRP-1 and VEGFR2. We found that NaPaC bound to all three molecules, VEGF165, VEGFR2 and NRP-1, but was more effective in inhibiting heparin binding to VEGF165. These results suggested that heparin binding sites of VEGFR2 and NRP-1 were different from those of VEGF165.