KIF13B-mediated VEGFR2 trafficking is essential for vascular leakage and metastasis in vivo.

VEGF-A induces vascular leakage and angiogenesis via activating the cell surface localized receptor VEGF receptor 2 (VEGFR2). The amount of available VEGFR2 at the cell surface is however tightly regulated by trafficking of VEGFR2 by kinesin family 13 B (KIF13B), a plus-end kinesin motor, to the plasma membrane of endothelial cells (ECs). Competitive inhibition of interaction between VEGFR2 and KIF13B by a peptide kinesin-derived angiogenesis inhibitor (KAI) prevented pathological angiogenesis in models of cancer and eye disease associated with defective angiogenesis. Here, we show the protective effects of KAI in VEGF-A-induced vascular leakage and cancer metastasis. Using an EC-specific KIF13B knockout (Kif13b iECKO ) mouse model, we demonstrated the function of EC expressed KIF13B in mediating VEGF-A-induced vascular leakage, angiogenesis, tumor growth, and cancer metastasis. Thus, KIF13B-mediated trafficking of VEGFR2 to the endothelial surface has an essential role in pathological angiogenesis induced by VEGF-A, and is therefore a potential therapeutic target.

VEGFR2 Trafficking by KIF13B Is a Novel Therapeutic Target for Wet Age-Related Macular Degeneration.

Purpose: Vascular endothelial growth factor (VEGF) and its receptor VEGFR2 are promising therapeutic targets for wet age-related macular degeneration (AMD). As a topically applicable option, we developed the peptide KAI to selectively interfere with VEGFR2 trafficking to the cell surface where it receives VEGF. This study sought to determine the efficacy of KAI in the mouse model of choroidal neovascularization (CNV). Methods: The specificity of KAI was tested by surface plasmon resonance. The drug delivery was analyzed by cryosection and the ELISA after treatment of KAI eyedrop to the mouse eyes. For the laser-induced CNV model, mice with laser-induced ruptures in Bruch's membrane received daily treatment of KAI eyedrop or control peptide. The other groups of mice received intravitreal injection of anti-VEGF or IgG control. After two weeks, CNV was quantified and compared. Results: First, we showed the specificity and high affinity of KAI to VEGFR2. Next, biodistribution revealed successful delivery of KAI eyedrop to the back of the mouse eyes. KAI significantly reduced the disease progression in laser-induced CNV. The comparison with current therapy suggests that KAI eyedrop is as effective as current therapy to prevent CNV in wet AMD. Moreover, the genetic deletion of a kinesin KIF13B, which mediates VEGFR2 trafficking to the cell surface, confirmed the pivotal role of KIF13B in disease progression of wet AMD and neovascularization from choroidal vessels. Conclusions: Taken together, pharmacologic inhibition and genetic deletion complementarily suggest the therapeutic possibility of targeting VEGFR2 trafficking to inhibit pathological angiogenesis in wet AMD.

A new entry to azomethine ylides from allylic amines and glyoxals: shifting the reliance on amino ester precursors.

The first examples of azomethine ylides derived from allylic amine and glyoxal precursors are reported. The condensation of primary allylic and α-aryl amines with glyoxylates or α-aryl glyoxals affords conjugated azomethine ylides that undergo facile [3 + 2] cycloaddition, providing 5-alkenyl pyrrolidine cycloadducts that cannot be accessed through the classical use of amino esters as ylide precursors.

Pyridone annulation via tandem Curtius rearrangement/6π-electrocyclization: total synthesis of (-)-lyconadin C.

A concise, enantioselective total synthesis of the Lycopodium alkaloid (-)-lyconadin C was achieved in 12 steps and high overall yield. Key features include construction of a luciduline congener through Mannich-type cyclization and a one-pot, tandem Curtius rearrangement/6π-electrocyclization to fashion the 2-pyridone system of lyconadin C.

Tandem iodine-mediated oxidations of tetrahydro-ß-carbolines: total synthesis of eudistomins Y1-Y7.

An efficient iodine-mediated oxidation of tetrahydro-ß-carbolines is described to yield aromatic ß-carboline products with tandem C-H oxidation. The utility of the method was demonstrated in total syntheses of the alkaloids eudistomins Y1-Y7.

Synthesis of functionalized indolizidines through Pauson-Khand cycloaddition of 2-allylpyrrolidines.

A concise entry to functionalized indolizidine scaffolds through a domino 2-aza-Cope-[3 + 2] dipolar cycloaddition and Pauson-Khand [2 + 2 + 1] cyclization has been accomplished. The process was conducted under mild conditions to afford diverse indolizidine systems as single diastereomers in good overall yields.

An aza-Prins cyclization approach to functionalized indolizidines from 2-allylpyrrolidines.

The stereoselective synthesis of a diverse set of functionalized indolizidine systems has been accomplished through the aza-Prins cyclization of 2-allylpyrrolidines. The condensation of aldehydes onto 2-allylpyrrolidines yields iminium ions that undergo highly diastereoselective aza-Prins cyclization, producing up to two stereogenic centers and two new rings in one step.

Total synthesis of the Aspidosperma alkaloid (±)-subincanadine F via a titanium-mediated intramolecular nucleophilic acyl substitution strategy.

The total synthesis of the bridge-fused Aspidosperma indole alkaloid (±)-subincanadine F has been accomplished in seven steps. The synthetic utility of a titanium-mediated intramolecular nucleophilic acyl substitution (INAS) reaction for the construction of the bridge-fused ring system was demonstrated.

Room-temperature aromatization of tetrahydro-ß-carbolines by 2-iodoxybenzoic acid: utility in a total synthesis of eudistomin U.

2-Iodoxybenzoic acid is a convenient reagent for the dehydrogenation of tetrahydro-ß-carbolines to their aromatic forms under mild conditions. The utility of the method was demonstrated in a total synthesis of the marine indole alkaloid eudistomin U.

Development of a 2-aza-Cope-[3 + 2] dipolar cycloaddition strategy for the synthesis of quaternary proline scaffolds.

A one-pot multicomponent procedure for the synthesis of highly functionalized pyrrolidine rings through a domino 2-aza-Cope-[3 + 2] dipolar cycloaddition sequence has been demonstrated. This protocol was found to be both high-yielding and stereoselective for the endo cycloadduct.

Inhibiting tumor growth by targeting tumor vasculature with galectin-1 antagonist anginex conjugated to the cytotoxic acylfulvene, 6-hydroxylpropylacylfulvene.

Targeted delivery of therapeutic drugs promises to become the norm to treat cancer. Here, we conjugated the cytotoxic agent 6-hydroxypropylacylfulvene (HPAF) to anginex, a peptide that targets galectin-1, which is highly expressed in endothelial cells of tumor vessels. In a human ovarian cancer model in mice, the conjugate inhibited tumor growth better than equivalent doses of either compound alone. Immunofluorescence on tumor tissue demonstrated that the conjugate, like parent anginex, selectively targeted tumor vasculature and inhibited tumor angiogenesis. Increased activity from the conjugate further suggests that HPAF retains at least some of its normal cytotoxic activity when linked to anginex. More importantly perhaps is the observation that the conjugate abrogates apparent systemic toxicity from treatment with HPAF. This work contributes to the development of tumor vascular targeting agents against cancer in the clinic.

Concise total syntheses of the Lycopodium alkaloids (+/-)-nankakurines A and B via luciduline.

Total syntheses of the Lycopodium alkaloids nankakurines A and B have been accomplished in 6 and 7 steps, respectively, via a sequence that passes through a third Lycopodium alkaloid, luciduline, and forgoes the use of protecting groups on nitrogen. Key features include a short preparation of luciduline followed by a concise and stereoselective aminoallylation/ring-closing metathesis protocol to fashion the spiropiperidine ring common to nankakurines A and B.

Enantioselective formal total synthesis of (+)-aspergillide C.

An enantioselective formal total synthesis of the cytotoxic macrolide (+)-aspergillide C has been accomplished from (S)-(-)-glyceraldehyde acetonide and the Danishefsky-Kitahara diene. Strategic transformations include a hetero Diels-Alder reaction, Ferrier-type addition, and palladium-catalyzed oxidative lactonization to set key stereocenters within the dihydropyran core, followed by fragment coupling via (E)-selective Julia-Kocienski olefination.

C5a, but not C3a, increases VEGF secretion in ARPE-19 human retinal pigment epithelial cells.

PURPOSE: We examined the potential for the pro-inflammatory complement proteins C5a and C3a to increase VEGF expression in ARPE-19 cells. MATERIALS AND METHODS: Expression of complement receptors in ARPE-19 cells was evaluated by RT-PCR. VEGF secretion from ARPE-19 cells treated with C5a or C3a was determined by ELISA. RESULTS: C5a and C3a receptor, but not C5L2, were detected in human eye tissue and ARPE-19 cells. C5a, but not C3a, treatment increased VEGF secretion from ARPE-19 cells, an effect inhibited by the C5aR antagonist, NDT 9513727. CONCLUSIONS: C5a receptor mediates increased VEGF secretion from ARPE-19 cells, suggesting a role for the C5a receptor in the pathogenesis of macular degeneration.

Delivery and visualization of proteins conjugated to quantum dots in cardiac myocytes.

The design of a novel transduction complex has permitted the introduction of protein-quantum dot conjugates into the cytoplasm of living cells. Appropriate subcellular localization of quantum dot-conjugated cardiac troponin C to the myofibrils and a nuclear peptide to the nucleus was attained in living cardiac myocytes using this approach. This new methodology opens the possibility for live tracking of exogenous proteins and study of protein dynamics.

Total syntheses of (+)- and (-)-peribysin E.

A convergent, stereocontrolled route to either antipode of the cell adhesion inhibitor, peribysin E, has been achieved from carvone. Highlights of the synthesis include a Diels-Alder reaction to generate a cis-decalin framework, followed by semipinacol-type ring contraction to secure the stereochemistry of the C7 quaternary center. Potential mechanistic pathways for the critical ring contraction were studied through deuterium incorporation studies. In addition, an optimized olefin isomerization/Saegusa oxidation protocol is described for the conversion of [4+2] cycloadducts of 2-(trialkylsilyloxy)-1,3-dienes to 1,6(2H,7H)-naphthalenediones, having stereochemical arrangements not accessible via conventional Robinson annulation protocols. Finally, the ability to independently prepare either enantiomer of peribysin E from the corresponding antipode of carvone led to a reassignment of the absolute configuration of peribysin E.

Ovarian tumor growth regression using a combination of vascular targeting agents anginex or topomimetic 0118 and the chemotherapeutic irofulven.

Combination of chemotherapeutic agents and angiogenesis inhibitors is now commonly employed in the clinic to treat cancer. Here, we used angiostatic agents anginex and 0118, in combination with the chemotherapeutic irofulven, to treat human ovarian tumor xenografts in mice. General linear mixed models were used to statistically analyze tumor growth curves. Overall, combination of a low, non-toxic dose of irofulven with either angiogenesis inhibitor was more effective at inhibiting tumor growth than any of the single agent therapies. For example, the anginex/irofulven and 0118/irofulven combinations inhibited tumor growth relative to controls by 92% (p<0.0001) and 96% (p<0.0001), respectively, with the 0118/irofulven combinations yielding 100% complete responses. This study suggests that combination therapy of 0118 or anginex and irofulven may be highly effective in the clinical setting.

Arsenic (+3 oxidation state) methyltransferase and the methylation of arsenicals.

Metabolic conversion of inorganic arsenic into methylated products is a multistep process that yields mono-, di-, and trimethylated arsenicals. In recent years, it has become apparent that formation of methylated metabolites of inorganic arsenic is not necessarily a detoxification process. Intermediates and products formed in this pathway may be more reactive and toxic than inorganic arsenic. Like all metabolic pathways, understanding the pathway for arsenic methylation involves identification of each individual step in the process and the characterization of the molecules which participate in each step. Among several arsenic methyltransferases that have been identified, arsenic (+3 oxidation state) methyltransferase is the one best characterized at the genetic and functional levels. This review focuses on phylogenetic relationships in the deuterostomal lineage for this enzyme and on the relation between genotype for arsenic (+3 oxidation state) methyltransferase and phenotype for conversion of inorganic arsenic to methylated metabolites. Two conceptual models for function of arsenic (+3 oxidation state) methyltransferase which posit different roles for cellular reductants in the conversion of inorganic arsenic to methylated metabolites are compared. Although each model accurately represents some aspects of enzyme's role in the pathway for arsenic methylation, neither model is a fully satisfactory representation of all the steps in this metabolic pathway. Additional information on the structure and function of the enzyme will be needed to develop a more comprehensive model for this pathway.

Pharmacokinetics, metabolism, and routes of excretion of intravenous irofulven in patients with advanced solid tumors.

Irofulven is currently in Phase 2 clinical trials against a wide variety of solid tumors and has demonstrated activity in ovarian, prostate, gastrointestinal, and non-small cell lung cancer. The objectives of this study were to determine its pharmacokinetics and route of excretion and to characterize its metabolites in human plasma and urine samples after a 30-min i.v. infusion at a dose of 0.55 mg/kg in patients with advanced solid tumors. Three patients were administered i.v. 100 microCi of [14C]irofulven over a 30-min infusion on day 1 of cycle 1. Serial blood and plasma samples were drawn at 0 (before irofulven infusion) and up to 144 h after the start of infusion. Urine and fecal samples were collected for up to 144 h after the start of infusion. The mean urinary and fecal excretion of radioactivity up to 144 h were 71.2 and 2.9%, respectively, indicating renal excretion was the major route of elimination of [14C]irofulven. The C(max), AUC(0-infinity), and terminal half-life values for total radioactivity were 1130 ng-Eq/ml, 24,400 ng-Eq . h/ml, and 116.5 h, respectively, and the corresponding values for irofulven were 82.7 ng/ml, 65.5 ng . h/ml, and 0.3 h, respectively, suggesting that the total radioactivity in human plasma was a result of the metabolites. Twelve metabolites of irofulven were detected in human urine and plasma by electrospray ionization/tandem mass spectrometry. Among these metabolites, the cyclopropane ring-opened metabolite (M2) of irofulven was found, and seven others were proposed as glucuronide and glutathione conjugates.

Investigation of a convergent route to purpuromycin: benzofuran formation vs spiroketalization.

[Structure: see text] A mild and efficient [3+2] nitrile oxide/olefin cycloaddition allows coupling of the highly functionalized naphthalene and isocoumarin hemispheres of purpuromycin. A rationale of the inability of advanced keto alcohols to spirocyclize is presented based upon a systematic examination of the electronic factors present in these systems and suggests that the biosynthesis of purpuromycin does not proceed through open-chain intermediates.