Analogues Of Neuropeptide Research Articles

GPR54-Dependent Stimulation of Luteinizing Hormone Secretion by Neurokinin B in Prepubertal Rats

Kisspeptin, neurokinin B (NKB) and dynorphin A (Dyn) are coexpressed within KNDy neurons that project from the hypothalamic arcuate nucleus (ARC) to GnRH neurons and numerous other hypothalamic targets. Each of the KNDy neuropeptides has been implicated in regulating pulsatile GnRH/LH secretion. In isolation, kisspeptin is generally known to stimulate, and Dyn to inhibit LH secretion. However, the NKB analog, senktide, has variously been reported to inhibit, stimulate or have no effect on LH secretion. In prepubertal mice, rats and monkeys, senktide stimulates LH secretion. Furthermore, in the monkey this effect is dependent on kisspeptin signaling through its receptor, GPR54. The present study tested the hypotheses that the stimulatory effects of NKB on LH secretion in intact rats are mediated by kisspeptin/GPR54 signaling and are independent of a Dyn tone. To test this, ovarian-intact prepubertal rats were subjected to frequent automated blood sampling before and after intracerebroventricular injections of KNDy neuropeptide analogs. Senktide robustly induced single LH pulses, while neither the GPR54 antagonist, Kp-234, nor the Dyn agonist and antagonist (U50488 and nor-BNI, respectively) had an effect on basal LH levels. However, Kp-234 potently blocked the senktide-induced LH pulses. Modulation of the Dyn tone by U50488 or nor-BNI did not affect the senktide-induced LH pulses. These data demonstrate that the stimulatory effect of NKB on LH secretion in intact female rats is dependent upon kisspeptin/GPR54 signaling, but not on Dyn signaling.

Anticonvulsant neuropeptides as drug leads for neurological diseases

Anticonvulsant neuropeptides are best known for their ability to suppress seizures and modulate pain pathways. Galanin, neuropeptide Y, somatostatin, neurotensin, dynorphin, among others, have been validated as potential first-in-class anti-epileptic or/and analgesic compounds in animal models of epilepsy and pain, but their therapeutic potential extends to other neurological indications, including neurodegenerative and psychatric disorders. Disease-modifying properties of neuropeptides make them even more attractive templates for developing new-generation neurotherapeutics. Arguably, efforts to transform this class of neuropeptides into drugs have been limited compared to those for other bioactive peptides. Key challenges in developing neuropeptide-based anticonvulsants are: to engineer optimal receptor-subtype selectivity, to improve metabolic stability and to enhance their bioavailability, including penetration across the blood–brain barrier (BBB). Here, we summarize advances toward developing systemically active and CNS-penetrant neuropeptide analogs. Two main objectives of this review are: (1) to provide an overview of structural and pharmacological properties for selected anticonvulsant neuropeptides and their analogs and (2) to encourage broader efforts to convert these endogenous natural products into drug leads for pain, epilepsy and other neurological diseases.

Neuropeptide receptor positive allosteric modulation in epilepsy: Galanin modulation revealed

The therapeutic potential of neuropeptides has long been recognized; some successes have been registered, for example, in the tachykinin, endothelin, somatostatin, angiotensin, calcitonin gene-related peptide (CGRP), orexin, or glucagon-like peptide 1 (GLP1) fields (1), primarily in peripheral applications. However, given the nature of receptor–ligand interactions at the orthosteric site of G protein-coupled receptors (GPCRs), which seem to involve multiple pharmacophores that are hard to display on low-molecular-weight (LMW) ligands, it is not surprising that the number of such ligands, especially agonists, is very limited, particularly considering brain-penetrant ones. This is not because large pharmaceutical companies have neglected modern high throughput screening technology to find such drug candidates. Many synthetic neuropeptide analogs exist, but most of them are peptides, with inherent limitations in biovailability, plasma half-life/proteolytic degradation, brain penetration, and cost of goods. More recently, alternate approaches in the GPCR field emerged with negative or positive allosteric modulators (PAM), acting as antagonists or agonists, but only in the presence of the endogenous agonist. Galanin, which acts on three GPCRs (GalR1–3), has long been proposed to play a role in seizures; however, with few exceptions, the tools described are still peptides or peptidomimetics. Now, Lu et al. (2) report in PNAS on the discovery of CYM2503, an LMW, potent, selective, and in vivo active GalR2 PAM, effective in several modalities linked to epilepsy in rodents.

Development of Gallium-68 Labeled Neuropeptide Analogs for Imaging NET by Positron Emission Tomography

Background: Gallium-68 (68Ga) labeled analogs of somatostatin (sst) have been demonstrated to be effective for imaging NETs by positron emission tomography (PET) in European clinical studies. These radiopharmaceuticals are more reliable (and prepared more conveniently) than fluorine-18 (18F) labeled glucose (18F-FDG) and dihydroxyphenylalanine (18F-DOPA); with superior image quality/sensitivity compared to indium-111 single-photon-emission computed tomography (SPECT). 68Ga-sst analogs target upregulation of sst receptor subtype-2 (sst2) in NETs. However, upregulated sst2 in NET is not ubiquitous and alternative-receptor targets (e.g., G-protein coupled receptors) are needed. We examined [68Ga]-labeled analogs of sst and neuropeptide-Y (NPY) for imaging xenograft NETs in rats. Methods: Cells (BON, SKNBE, SHSY5Y) were cultured by standard techniques. Sst analog tyr3-octreotide (TOC) and NPY derivative YPSKxRHYINLITRQRY (NxPY; targeting NPY receptor subtype 2; x = hexanoic acid) were conjugated to chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) by standard methods. Radiolabeling was performed at pH 3.5 (100°C, 10-20 minutes). Competitive binding assays established receptor specificity. Tumors were induced by subcutaneous flank injection of cells in nude rats (∼4 weeks). Radiochemical purity (RP) and specific activity (SA) were monitored by radioHPLC. Imaging was performed using a Phillips Mosaic microPET. Results: Binding assays demonstrate receptor specific binding with low IC50's (nM range) for [68Ga]-DOTATOC and [68Ga]-DOTANxPY. Western blots confirmed receptor expression. Dynamic PET imaging of [68Ga]-DOTATOC (15.6 MBq) revealed SKNBE2 tumor:background accumulated to a constant value of 7 (120 min. PI), while BON tumor activity increased for approximately 60 minutes and then decreased to a final value of 3.6 (120 min. PI). Static imaging of [68Ga]-DOTANxPY (11.6 MBq) revealed a tumor(SHSY5Y):background of 2 at 60 min. PI. Radiolabeling results: Conclusions: These results prepare us to move forward with [68Ga]-DOTATOC for early phase PET imaging trials of NETs. [68Ga]-DOTANPY is a promising radiopharmaceutical.

VRQ397 (CRAVKY): a novel noncompetitive V2 receptor antagonist

Vasopressin type 2 receptor (V2R) exhibits mostly important properties for hydroosmotic equilibrium and, to a lesser extent, on vasomotricity. Drugs currently acting on this receptor are analogs of the natural neuropeptide, arginine vasopressin (AVP), and hence are competitive ligands. Peptides that reproduce specific sequences of a given receptor have lately been reported to interfere with its action, and if such molecules arise from regions remote from the binding site they would be anticipated to exhibit noncompetitive antagonism, but this has yet to be shown for V2R. Six peptides reproducing juxtamembranous regions of V2R were designed and screened; the most effective peptide, cravky (labeled VRQ397), was characterized. VRQ397 was potent (IC(50) = 0.69 +/- 0.25 nM) and fully effective in inhibiting V2R-dependent physiological function, specifically desmopressin-L-desamino-8-arginine-vasopressin (DDAVP)-induced cremasteric vasorelaxation; this physiological functional assay was utilized to avoid overlooking interference of specific signaling events. A dose-response profile revealed a noncompetitive property of VRQ397; correspondingly, VRQ397 bound specifically to V2R-expressing cells could not displace its natural ligand, AVP, but modulated AVP binding kinetics (dissociation rate). Specificity of VRQ397 was further confirmed by its inability to bind to homologous V1 and oxytocin receptors and its inefficacy to alter responses to stimulation of these receptors. VRQ397 exhibited pharmacological permissiveness on V2R-induced signals, as it inhibited DDAVP-induced PGI(2) generation but not that of cAMP or recruitment of beta-arrestin2. Consistent with in vitro and ex vivo effects as a V2R antagonist, VRQ397 displayed anticipated in vivo aquaretic efficacy. We hereby describe the discovery of a first potent noncompetitive antagonist of V2R, which exhibits functional selectivity, in line with properties of a negative allosteric modulator.

Towards Understanding the Free and Receptor Bound Conformation of Neuropeptide Y by Fluorescence Resonance Energy Transfer Studies

Despite a considerable sequence identity of the three mammalian hormones of the neuropeptide Y family, namely neuropeptide Y, peptide YY and pancreatic polypeptide, their structure in solution is described to be different. A so-called pancreatic polypeptide-fold has been identified for pancreatic polypeptide, whereas the structure of the N-terminal segment of neuropeptide Y is unknown. This element is important for the binding of neuropeptide Y to two of its relevant receptors, Y(1) and Y(5), but not to the Y(2) receptor subtype. In this study now, three doubly fluorescent-labeled analogs of neuropeptide Y have been synthesized that still bind to the Y(5) receptor with high affinity to investigate the conformation in solution and, for the first time, to probe the conformational changes upon binding of the ligand to its receptor in cell membrane preparations. The results obtained from the fluorescence resonance energy transfer investigations clearly show considerable differences in transfer efficiency that depend both on the solvent as well as on the peptide concentration. However, the studies do not support a pancreatic polypeptide-like folding of neuropeptide Y in the presence of membranes that express the human Y(5) receptor subtype.

FMRFamide-related peptides (FaRPs): A new family of peptides from amphibian defensive skin secretions

Amphibian defensive skin secretions are known to contain a plethora of biologically-active peptides that are often structural and functional analogues of vertebrate neuropeptides. Here we report the structures of two invertebrate neuropeptide analogues, IPPQFMRF amide (IF-8 amide) and EGDEDEFLRF amide (EF-10 amide), from the defensive skin secretions of two different species of African hyperoliid frogs, Kassina maculata and Phylictimantis verrucosus, respectively. These represent the first canonical FMRF amide-related peptides (FaRPs) from a vertebrate source. The cDNA encoding IF-8 amide was cloned from a skin secretion library and found to contain a single copy of the peptide located at the C-terminus of a 58 amino acid residue open-reading frame. These data extend the potential targets of the defensive arsenal of amphibian tegumental secretions to parasitic/predatory invertebrates and the novel peptides described may represent the first vertebrate peptidic endectocides.

Orthogonal solid-phase synthesis of a monobiotinylated analog of neuropeptide Y.

Analogs of Neuropeptide Y (NPY) were synthesized with conventional Boc/benzyl protective group strategy. Instead of Asn7 in the native sequence, Boc-Lys(Alloc)-OH was incorporated. At the end of the synthesis the Alloc group was selectively removed by palladium-catalyzed hydrostannolysis and biotin coupled to the epsilon-amino group of Lys7. After cleavage and characterization with plasma desorption mass spectrometry the N epsilon,7-biotinyl-[Lys7]-NPY and the nonbiotinylated analog [Lys7]-NPY were investigated as ligands to the NPY receptor from rat cerebral cortex. Both analogs were found to be high affinity ligands to the NPY receptor and bound with essentially the same affinity as unmodified NPY.

A bifunctional heterodimeric insect neuropeptide analog.

The synthesis and biological activity of a bifunctional, heterodimeric insect neuropeptide analog are described. The heterodimer is composed of the C-terminal pentapeptide active core regions of the leucokinin/achetakinin and pyrokinin neuropeptide families linked via their N-terminal amino groups with a succinyl diacid moiety. Members of the leucokinin/achetakinin family can induce fluid secretion in malpighian tubules of the house cricket, Acheta domesticus, whereas the pyrokinins demonstrate activity in a cricket oviduct myotropic bioassay. No cross-activity is observed for the two neuropeptide families in these bioassays. However, the heterodimer elicits responses in both Acheta bioassays. Such a bifunctional analog may in future serve as a template for the design of stable, bifunctional pest insect control agents of greater efficiency.

Novel Chemically Modified Analogues of Neuropeptide Y for Tumor Targeting

The successful use of peptides as potential radiopharmaceuticals essentially requires the modification of the bioactive peptide hormones to introduce chelators for radiolabeling. In this study, four Y 1/Y 2 receptor-selective NPY analogues with different receptor subtype specificities have been investigated. For in vitro studies, the cold metal surrogate was used. Gallium and indium complexes were introduced by using 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid as bifunctional chelator. The peptides were synthesized by solid-phase peptide synthesis (SPPS), the chelator was coupled either at the N-terminus or at the N(epsilon) side chain of Lys(4) of the resin-bound peptide, and the labeling was performed in solution after cleavage. Competitive binding assays showed high binding affinity of the receptor-selective analogues at NPY receptor expressing cells. To test internalization of the novel peptide analogues and the metabolic stability in human blood plasma, the corresponding 5(6)-carboxyfluorescein (CF) analogues were prepared and investigated. One of the most promising analogues, the Y 1-receptor selective [Lys(DOTA)(4), Phe(7), Pro(34)]NPY was labeled with (111)In and injected into nude mice that bear MCF-7 breast cancer xenografts, and biodistribution studies were performed. In vitro and in vivo studies suggest that receptor-selective analogues of NPY have promising characteristics for future applications in nuclear medicine for breast tumor diagnosis and therapy.

Recent advances in the neurobiology of anxiety disorders: Implications for novel therapeutics

Anxiety disorders are a highly prevalent and disabling class of psychiatric disorders. This review focuses on new directions in neurobiological research and implications for the development of novel psychopharmacological treatments. Neuroanatomical and neuroimaging research in anxiety disorders has centered on the role of the amygdala, reciprocal connections between the amygdala and the prefrontal cortex, and, most recently, alterations in interoceptive processing by the anterior insula. Anxiety disorders are characterized by alterations in a diverse range of neurochemical systems, suggesting ample novel targets for drug therapies. Corticotropin-releasing factor (CRF) concentrations are elevated in a subset of anxiety disorders, which suggests the potential utility of CRF receptor antagonists. Pharmacological blockade of the memory-enhancing effects of stress hormones such as glucocorticoids and noradrenaline holds promise as a preventative approach for trauma-related anxiety. The glutamatergic system has been largely overlooked as a potential pharmacological target, although convergent preclinical, neuroimaging, and early clinical findings suggest that glutamate receptor antagonists may have potent anxiolytic effects. Glutamatergic receptor agonists (e.g., D-cycloserine) also have an emerging role in the treatment of anxiety as facilitators of fear extinction during concurrent behavioral interventions. The neuropeptides substance P, neuropeptide Y, oxytocin, orexin, and galanin are each implicated in anxiety pathways, and neuropeptide analogs or antagonists show early promise as anxiolytics in preclinical and/or clinical research. Each of these active areas of research holds promise for expanding and improving evidence-based treatment options for individuals suffering with clinical anxiety.

Proline Derived Spirobarbiturates as Highly Effective β-Turn Mimetics Incorporating Polar and Functionalizable Constraint Elements

A practical and efficient synthesis of spirobarbiturates of type III is reported when NH acidity of the imide function of the hydrophilic linker element allowed the introduction of different substituents. Structural characterization, which was based on both X-ray crystallography and spectroscopic investigations, indicated type II beta-turn formation. Introduction of the molecular scaffold into solid phase peptide synthesis gave rise to spirocyclic neuropeptide analogs.

Modulation of key signal transduction molecules by a novel peptide combination effective for the treatment of gastrointestinal carcinomas

We have reported earlier a novel combination of four structurally designed synthetic neuropeptide analogs of vasoactive intestinal peptide (VIP), bombesin, substance P and somatostatin, code-named DRF 7295 which have anti-tumor efficacy for adenocarcinomas in vitro and in vivo (Jaggi et al., Invest New Drugs, 2008). The discovery, synthesis, in vitro and in vivo efficacy was reported (Jaggi et al., Invest New Drugs, 2008). Gastrointestinal tumor cells of the colon, pancreas and duodenum were found to most sensitive to DRF7295 in vitro and in vivo (Jaggi et al., Invest New Drugs, 2008). We have further investigated and report here the modulation of cellular signaling in gastrointestinal carcinomas by DRF 7295, which may be mediating its observed anticancer activity in these cancer types. DRF 7295 inhibits the binding of specific neuropeptides initiating a cascade of cellular signaling events leading to programmed cell death. It down regulates the second messenger cAMP, epidermal growth factor (EGF) dependent proliferation and the phosphorylated MAP Kinase pERK1/2 in gastrointestinal carcinomas, thus depriving the tumour cells of critical pro-proliferative cellular signals. It triggers bcl2 and Caspase 3 dependent apoptotic cell death and induces p53 tumor suppressor protein in the treated carcinoma cells in vitro. It has significant anti-angiogenic potential as reflected in the inhibition of tube like formation in the endothelial cells and down regulation of VEGF levels. Tumour xenograft studies confirmed the in vivo efficacy of DRF 7295 for gastrointestinal carcinomas (Jaggi et al., Invest New Drugs, 2008). The Phase I clinical trials have shown DRF 7295 to be well tolerated and devoid of systemic toxicities of the conventional cytotoxics (Mukherjee et al., Phase I dose escalating study of DRF7295: a new class of peptide based drugs. "Abstract" ASCO ID:948, 2003). The drug may have a promising role in disease stabilization in colorectal and other cancers. Thus DRF 7295 is a novel targeted drug in the class of signal transduction modulators, with potential for treatment of gastrointestinal carcinomas.

Anticancer activity of a peptide combination in gastrointestinal cancers targeting multiple neuropeptide receptors

A novel peptide combination consisting of four synthetic neuropeptide analogs of Vasoactive Intestinal Peptide (VIP), Bombesin, Substance P and Somatostatin has been found to have potent anticancer activity in vitro and in vivo. The receptors of these four neuropeptides are known to be over expressed in various cancers. We have found the presence of native neuropeptides in the culture supernatant of the primary tumor cells of human colon adenocarcinomas. It was further demonstrated by receptor-ligand assays that not only do these tumor cells synthesize and secrete four peptide hormones but also possess specific high affinity receptors on their surface. Screening a large panel of analogs to the four peptide hormones on tumor cell proliferation led to the identification of four cytotoxic analogs, the combination of which was code-named DRF7295. The design and synthesis of the peptide analogs have been described in this paper. In vitro anticancer activity of DRF7295 was studied in a large panel of human tumor cells. Gastrointestinal tumor cells of the colon, pancreas and duodenum were found to be most sensitive to DRF7295 with moderate activity seen in glioblastoma, prostate, leukemia and those of oral cancer cells. Efficacy studies in xenograft models of colon and duodenum resulted in T/C% of less than 40%, which is indicative of strong tumor regressing potential of DRF7295 in gastrointestinal cancers. Acute and long-term toxicity studies as well as safety pharmacology studies conducted indicate the safety of the drug upon systemic administration with no significant adverse pharmacological effects.

Backbone cyclic pheromone biosynthesis activating neuropeptide (PBAN) antagonists: Inhibition of melanization in the moth Spodoptera littoralis (Insecta, Lepidoptera)

Antagonistic and agonistic activities of backbone cyclic (BBC) pheromone biosynthesis activating neuropeptide (PBAN) analogues were evaluated in an attempt to identify potent melanotropic antagonists, to gain an insight into their structure–activity relationship (SAR), and to discover molecules with selective and non-selective melanotropic and pheromonotropic properties. Eight potent melanotropic BBC antagonists and seven agonists were disclosed. SAR studies revealed that the structural requirements of the melanotropic and pheromonotropic agonists and antagonists are different. The cyclic structure of the BBC peptides was unimportant for antagonistic activity, and linearization retained their melanotropic and pheromonotropic antagonistic properties. Comparison of the antagonistic activities of the BBC and precyclic peptides with respect to both functions revealed eight selective antagonists (six that were selective melanotropic antagonists and two selective pheromonotropic antagonists) and four non-selective (melanotropic and pheromonotropic) antagonists. The selective melanotropic antagonists exhibited both, pure or mixed agonistic/antagonistic activities. The selective pheromonotropic compounds were pure antagonists. All non-selective compounds were pure antagonists. Comparison of the agonistic activities of the BBC peptides with respect to both functions revealed six selective melanotropic agonists and one non-selective agonistic compound. All compounds (whether selective or non-selective) exhibited pure agonistic activity. Discovery of the selective compounds hints at the possibility that the receptors that mediate the respective activities may have different properties.

Designing nootropic dipeptides using an evolutionary-genetic approach

A novel approach to the search for the new groups of biologically active peptides is developed, which is based on the selection of point mutants with respect to noncritical amino acid residues. Using a gene site encoding the arginine vasopressin AVP(4–5) sequence, which corresponds to the pGlu-Asn-NH2 nootropic dipeptide, three point mutants with respect to Asn (pGlu-Ser-NH2, pGlu-Asp-NH2, and pGlu-His-NH2) have been synthesized. The first two peptides (corresponding to transitions of the 1st and 2nd bases, respectively) display nootropic activity in the passive avoidance test in rats at a dose of 0.1 mg/kg (i.p.). The last peptide (corresponding to a transversion of the 1st base) proved to be inactive. Both active peptides exhibit electronic and structural differences from the parent dipeptide: pGlu-Asp-NH2 bears a negative charge and contains a primary alcohol group instead of the amide moiety. Using the proposed method, it is possible to create genetically related analogs of well-known neuropeptides with substantially different structures.

The Solution Structure of a Cyclic Analog of Neuropeptide Y with High Y1 Receptor Affinity by NMR, CD and MD Simulations

The conformation of a cyclic analog of neuropeptide Y [Tyr1--Lys--Gly--Arg--cyclo5/8-(Glu5--Tyr--Ile--Lys8)--Leu--Ile10--Thr--Arg--Pro--Arg--Tyr15--NH2; cEK-NPY] with high Y1 receptor affinity was studied using 1H, 13C and 15N 2D-NMR and CD in three diverse media-viz. DMSO-d6, water (pH 4.0) and 50% hexafluoroacetone (HFA). The conformation of cEK-NPY was interpreted based on chemical shift (1H, 13C and 15N), temperature coefficients of the NH chemical shifts, 3JNHα coupling constants and the pattern of intra and inter-residue NOE’s and the CD spectrum. In both DMSO and water, there is a preponderance of a β-strand structure, while HFA promotes an α-helical structure, which is discontinuous in the mid-region of the peptide, due to the constraints of the lactam ring. The solution structures were generated using Restrained Molecular Dynamics simulations and further refined by Mardigras to R factors between 0.55 and 0.65. The role of its conformations in its biological activity is discussed.

Aliphatic amino diacid Asu functions as an effective mimic of Tyr(SO 3H) in sulfakinins for myotropic and food intake-inhibition activity in insects

The aliphatic amino diacid α-aminosuberic acid can function as an effective, stable mimic of the hydrolysis-susceptible Tyr(SO 3H) group in sulfakinin neuropeptide analogs for both hindgut contractile activity in cockroach and food intake-inhibition activity in the desert locust. In the analog, the acidic sulfate group is replaced with an acidic carboxyl group. The degree of activity of sulfakinin analogs is correlated with the carboxyl/α-carbon distance in the cockroach hindgut contractile assay. The results represent an important step in the design and synthesis of biostable, sulfakinin analogs that could potentially suppress the feeding behavior of destructive insect pests of agricultural importance.

Modeling of Neuropeptide Receptors Y1, Y4, Y5, and Docking Studies with Neuropeptide Antagonist Analogues: Implications for Selectivity

Neuropeptide Y (NPY), receptors belong to the G-protein coupled receptor superfamily. NPY mediates several physiological responses, such as blood pressure, food intake, sedation. These actions of NPY are mediated by six receptor subtypes denoted as Y1-Y5 and y6. Modeling of receptor subtypes and binding site identification is an important step in developing new therapeutic agents. We have attempted to model the three NPY receptor types, Y1, Y4, and Y5 using homology modeling and threading methods. The models are consistent with previously reported experimental evidence. To understand the interaction and selectivity of NPY analogues with different neuropeptide receptors, docking studies of two neuropeptide analogues (BVD10 and BVD15) with receptors Y1 and Y4 were carried out. Results of the docking studies indicated that the interaction of ligands BVD10 and BVD15 with Y1 and Y4 receptors are different. These results were evaluated for selectivity of peptide analogues BVD10 and BVD15 towards the receptors.

Phase I dose escalation study on DRF 7295: A novel peptide based anticancer drug, in patients with advanced, metastatic adenocarcinomas: Final results

3094 Background: DRF 7295 is a novel combination of 4 synthetic neuropeptide analogues having antiproliferative, antiangiogenic and proapoptotic properties. It has exhibited potent preclinical acti...