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Using Cu(I)-catalyzed azide-alkyne cycloaddition in a mixed classical organic phase and solid phase peptide synthesis approach, we synthesized four analogs of Leu-enkephalin to systematically replace amides by 1,4-disubstituted[1,2,3]triazoles. The peptidomimetics obtained were characterized by competitive binding, contractility assays and ERK1/2 phosphorylation. The present study reveals that the analog bearing a triazole between Phe and Leu retains some potency, more than all the others, suggesting that the hydrogen bond acceptor capacity of the last amide of Leu-enkephalin is essential for the biological activity of the peptide.

Reported herein is the iteration of a strategy employing a Mukaiyama reaction in tandem with a hydrogen transfer reaction for the elaboration of four polypropionate motifs containing the anti – anti unit. In this process, Lewis acid acts as the key element in controlling the diastereoselectivity of each step, the outcome of which is >20:1 for all of the reactions performed.

Background The weak efficiency of plasmid transfer into the cytosol remains one of the major limiting factors to achieve an efficient transfection with DNA/cationic polymer complexes. We found that divalent metal Zn2+ can improve the polyfection efficiency, especially with DNA/histidylated polylysine (His-pLK) complexes. Methods and results The supplementation of the transfection medium with 250 µM ZnCl2 increased the polyfection of human hepatocarcinoma (HepG2) cells with a plasmid encoding EGFP complexed with pLK, polyethyleneimine and His-pLK. Zn2+ is more efficient on DNA/His-pLK complexes: the number of EGFP-positive cells increased from 1% to more than 40%. This phenomenon is selective to Zn2+ because no effect was obtained with other divalent cations. The effect of zinc varies from cell to cell. The binding of Zn2+ to histidyl residues might increase zinc endosomal concentration favoring membrane fusion. Flow cytometry and confocal microscopy studies clearly indicate that with His-pLK, the plasmid is better delivered in the cytosol as well as in the cell nucleus in zinc-treated cells. An investigation conducted with the histidine-rich peptide H5WYG showed that zinc inhibits membrane permeabilization but promotes membrane fusion as evidenced by resonance energy transfer. Conclusions Data reported here imply that the addition of zinc ions in the transfection medium can trigger an increase of the fusion of endosomes containing polyplexes which is more effective in the presence of histidine-rich molecules. Consequently, the amount of plasmid in the cytosol available to reach the nucleus is increased leading to an improvement of polyfection. Copyright © 2002 John Wiley & Sons, Ltd.

Background Glycosylated polylysines and histidylated polylysines complexed with plasmid DNA (pDNA) were proposed to develop polymer-based gene delivery systems. The present work has been undertaken in two steps to study the uptake and the intracellular processing of pDNA, which are still poorly understood in the polyfection pathway. Methods and results The kinetics of the uptake and the intracellular processing of pDNA complexed with lactosylated polylysine, histidylated polylysine or histidylated polylysine bearing lactosyl residues (polyplexes) into a CF human airway epithelial cell line were assessed by flow cytometry and confocal microscopy. Complexes formed from histidylated polylysine, even though they were less taken up by cells, show better transfection efficiency with compared with lactosylated complexes. Lactosylated polymers segregated more rapidly when compared with non-lactosylated polymers into compartments different from those containing pDNA on internalization. Intracellular location and pH measurements indicated that polymers ended up in compartments of pH ∼6.2 while pDNA reached less acidic compartments of pH ∼6.6. These compartments did not contain the LAMP-1 lysosomal marker. Conclusions The present study exhibits that, upon internalization, pDNA and polylysine conjugates underwent segregation with a rate depending on the polylysine substitution and polymer degradation. The better transfection efficiency of polyplexes with histidylated polylysine can be ascribed to their prolonged stability inside the endocytic vesicles that likely favored the pDNA escape in the cytosol. Copyright © 2002 John Wiley & Sons, Ltd.

A new method for the preparation of Xxx-Gly (E)-alkene dipeptide isosteres (EADIs), using LDA deprotonation followed by 1 N HCl quench, was explored. The method, named kinetic deconjugation, enabled the synthesis of Tyr-Gly, Gly-Gly, Ser-Gly, Pro-Gly, and Phe-Gly EADIs, as well as one Tyr-Gly trisubstituted alkene dipeptide isostere (TADI). Overall, this method, based on commercially available materials, leads to high yields, requires few synthetic steps and works on the gram scale in the synthesis of a wide variety of EADIs.

Both brown adipose tissue (BAT) and skeletal muscle activation contribute to the metabolic response of acute cold exposure in healthy men even under minimal shivering. Activation of adipose tissue intracellular lipolysis is associated with BAT metabolic response upon acute cold exposure in healthy men. Although BAT glucose uptake per volume of tissue is important, the bulk of glucose turnover during cold exposure is mediated by skeletal muscle metabolic activation even when shivering is minimized.Cold exposure stimulates the sympathetic nervous system (SNS), triggering the activation of cold-defence responses and mobilizing substrates to fuel the thermogenic processes. Although these processes have been investigated independently, the physiological interaction and coordinated contribution of the tissues involved in producing heat or mobilizing substrates has never been investigated in humans. Using [U-(13)C]-palmitate and [3-(3)H]-glucose tracer methodologies coupled with positron emission tomography using (11)C-acetate and (18)F-fluorodeoxyglucose, we examined the relationship between whole body sympathetically induced white adipose tissue (WAT) lipolysis and brown adipose tissue (BAT) metabolism and mapped the skeletal muscle shivering and metabolic activation pattern during a mild, acute cold exposure designed to minimize shivering response in 12 lean healthy men. Cold-induced increase in whole-body oxygen consumption was not independently associated with BAT volume of activity, BAT oxidative metabolism, or muscle metabolism or shivering intensity, but depended on the sum of responses of these two metabolic tissues. Cold-induced increase in non-esterified fatty acid (NEFA) appearance rate was strongly associated with the volume of metabolically active BAT (r = 0.80, P = 0.005), total BAT oxidative metabolism (r = 0.70, P = 0.004) and BAT glucose uptake (r = 0.80, P = 0.005), but not muscle glucose metabolism. The total glucose uptake was more than one order of magnitude greater in skeletal muscles compared to BAT during cold exposure (674 ± 124 vs. 12 ± 8 μmol min(-1), respectively, P0.001). Glucose uptake demonstrated that deeper, centrally located muscles of the neck, back and inner thigh were the greatest contributors of muscle glucose uptake during cold exposure due to their more important shivering response. In summary, these results demonstrate for the first time that the increase in plasma NEFA appearance from WAT lipolysis is closely associated with BAT metabolic activation upon acute cold exposure in healthy men. In humans, muscle glucose utilization during shivering contributes to a much greater extent than BAT to systemic glucose utilization during acute cold exposure.

Despite decades of research, the median survival of glioblastoma (GBM) patients remains 14.6 months. The presence of the blood-brain barrier (BBB) limits CNS antineoplastic drugs delivery. Many BBB characteristics are involved in the drug delivery limitation, amongst them the efflux pumps. Different delivery strategies, such as the osmotic blood-brain barrier disruption (BBBD) have been developed and used with success in GBM patients. In order to enhance BBBD efficacy, more information is needed about its dynamic process. The aim of this study was to determine if the BBBD procedure can enable the delivery of efflux pump substrates to brain parenchyma and glioma cells. Thirty-two F98-Fischer rats were randomly assigned to 6 groups: 1: control; 2: tariquidar (P-glycoprotein (PGP) inhibitor); 3: BBBD in tumor ipsilateral hemisphere; 4: tariquidar vehicle (n = 3); 5: BBBD negative control (n = 3); and 6: BBBD + tariquidar. An MRI scan was performed to allow PET-MRI images coregistration. A 1-h dynamic PET acquisition was obtained and, with 11C-Carvedilol (a PGP substrate) administered iv during the first minute of the scan. Four volumes of interest (VOI) were studied: tumor volume, distal volume to the tumor in the ipsilateral parenchyma and equivalent control VOIs in the contralateral hemisphere. 11C-Carvedilol uptake ratios of corresponding ipsilateral and contralateral VOIs were computed for every animal. 11C-Carvedilol uptake in tumors was significantly higher on average in tariquidar and BBBD + tariquidar groups compared to the control groups. When comparing 11C-Carvedilol uptake in parenchyma, there was no significant difference between the groups at study. However, only two out of six animals in the BBBD + tariquidar group did show higher 11C-Carvedilol uptake, indicating that the BBBD must be excellent for effective substrate delivery to CNS. These results demonstrate that the BBBD procedure does not allow significant delivery of efflux pump substrates to the CNS, unless excellent BBBD procedure is achieved.

Convenient approaches for the synthesis of DOTHA2 and NOTHA2, two cyclic bifunctional chelates (BFCs) bearing hydroxamate arms, have been developed. These novel BFCs coordinate (64)Cu with fast kinetics at room temperature in a wide range of concentrations and pH. The corresponding radiochemical complexes showed high stability, low residual activity in various tissues, and fast clearance in normal mice. The ability to conjugate DOTHA2 to both a small peptide and a large protein is also reported.

Context: Recent studies examining brown adipose tissue (BAT) metabolism in adult humans have provided convincing evidence of its thermogenic potential and role in clearing circulating glucose and fatty acids under acute mild cold exposure. In contrast, early indications suggest that BAT metabolism is defective in obesity and type 2 diabetes, which may have important pathological and therapeutic implications. Although many mammalian models have demonstrated the phenotypic flexibility of this tissue through chronic cold exposure, little is known about the metabolic plasticity of BAT in humans. Objective: Our objective was to determine whether 4 weeks of daily cold exposure could increase both the volume of metabolically active BAT and its oxidative capacity. Design: Six nonacclimated men were exposed to 10°C for 2 hours daily for 4 weeks (5 d/wk), using a liquid-conditioned suit. Using electromyography combined with positron emission tomography with [11C]acetate and [18F]fluorodeoxyglucose, shivering intensity and BAT oxidative metabolism, glucose uptake, and volume before and after 4 weeks of cold acclimation were examined under controlled acute cold-exposure conditions. Results: The 4-week acclimation protocol elicited a 45% increase in BAT volume of activity (from 66 ± 30 to 95 ± 28 mL, P < .05) and a 2.2-fold increase in cold-induced total BAT oxidative metabolism (from 0.725 ± 0.300 to 1.591 ± 0.326 mL·s−1, P < .05). Shivering intensity was not significantly different before compared with after acclimation (2.1% ± 0.7% vs 2.0% ± 0.5% maximal voluntary contraction, respectively). Fractional glucose uptake in BAT increased after acclimation (from 0.035 ± 0.014 to 0.048 ± 0.012 min−1), and net glucose uptake also trended toward an increase (from 163 ± 60 to 209 ± 50 nmol·g−1·min−1). Conclusions: These findings demonstrate that daily cold exposure not only increases the volume of metabolically active BAT but also increases its oxidative capacity and thus its contribution to cold-induced thermogenesis.

[reaction: see text] A tandem process featuring intramolecular aminyl radical cyclofunctionalization and hydrogen transfer affords 2,3-trans-disubstituted pyrrolidines with anti or syn diastereoselectivity. The extension of this strategy to iminyl radicals gives trans-anti pyrrolenines with high levels of 1,2-induction in both steps of the tandem process.

The radical allylation of a series of α-halo or α-phenylseleno-β-alkoxy esters in the presence of MgBr2·OEt2 is reported and compared with analogous reactions under non-chelating conditions. The addition of MgBr2·OEt2 gives excellent selectivity favoring anti products; in some cases ratios >100:1 are obtained. Varying the substrate substituents reveals that these reactions are quite tolerant of alkyl functionalities at the β-position. Changes to the alkoxy function indicate that a chelate is involved in the reaction. The reactions are successful with secondary iodides, bromides, and phenylselenides, as well as tertiary iodides, which all give very high ratios under chelation control. Performing less well under the same conditions are substrates with a radical exocyclic to a tetrahydrofuran ring. EDTA titration is used to determine the amount of Mg2+ dissolved in the allylation reaction mixture, and 13C NMR is employed to better define the nature of the complex formed (chelate or monodentate) prior to the reaction. Competition experiments suggest that the chelate and monodentate pathways are in competition for the radical allylation with allyltributyltin.Key words: allylation, radicals, Lewis acid, stereoselectivity, 1,2-induction.

Leu-enkephalin analogues, in which the amide bonds were sequentially and systematically replaced either by ester or N-methyl amide bonds, were prepared using classical organic chemistry as well as solid phase peptide synthesis (SPPS). The peptidomimetics were characterized using competition binding, ERK1/2 phosphorylation, receptor internalization, and contractility assays to evaluate their pharmacological profile over the delta opioid receptor (DOPr). The lipophilicity (LogD7.4) and plasma stability of the active analogues were also measured. Our results revealed that the last amide bond can be successfully replaced by either an ester or an N-methyl amide bond without significantly decreasing the biological activity of the corresponding analogues when compared to Leu-enkephalin. The peptidomimetics with an N-methyl amide function between residues Phe and Leu were found to be more lipophilic and more stable than Leu-enkephalin. Findings from the present study further revealed that the hydrogen-bond donor properties of the fourth amide of Leu-enkephalin are not important for its biological activity on DOPr. Our results show that the systematic replacement of amide bonds by isosteric functions represents an efficient way to design and synthesize novel peptide analogues with enhanced stability. Our findings further suggest that such a strategy can also be useful to study the biological roles of amide bonds.

Multimodal imaging is quickly becoming a standard in pre-clinical studies, and new developments have already confirmed the strength of acquiring and analyzing parallel information obtained in a single imaging session. One such application is the introduction of an internal reference moiety (e.g. radioisotope) to an activatable fluorescent probe. One of the limitations of this approach consists of working at concentrations which are within the overlapping range of sensitivities of each modality. In the case of PET/Fluorescence imaging, this range is in the order of 10-9 nM. Working in epi-illumination fluorescence imaging at such concentrations remains challenging. Here, we present in vitro and in vivo detection limits of a new fluorescent compound.

Acetylene-bearing 2-[(18)F]fluoropyridines [(18)F]FPy5yne and PEG-[(18)F]FPyKYNE were prepared via efficient nucleophilic heteroaromatic [(18)F]fluorination of their corresponding 2-trimethylammoniumpyrdinyl precursors. The prosthetic groups were conjugated to azide- and PEG3-modified bombesin(6-14) analogues via copper-catalyzed azide-alkyne cycloaddition couplings to yield mono- and di-mini-PEGylated ligands for PET imaging of the gastrin- releasing peptide receptor. The PEG3- and PEG2/PEG3-bearing (18)F peptides showed decreased lipophilicity relative to an analogous non-mini-PEGylated (18)F peptide. Assessment of water-soluble peptide pharmacokinetics and tumour-targeting capabilities in a mouse model of prostate cancer is currently underway.

The radical allylation of a series of β-alkoxy esters using allyltrimethylsilane in the presence of MgBr2· OEt2 is described. Under bidentate chelation-controlled conditions, allyltrimethylsilane r...

Fluorescence imaging (FI) provides increased sensitivity for the detection of bladder tumors compared to white light cystoscopy. However, most advanced dyes used in FI suffer from nonspecific cellular accumulation resulting in increased false-positives. In addition, these dyes have not made significant progress in detecting the most aggressive bladder tumors such as muscle invasive bladder cancer (MIBC). Our objective is to develop an antibody-conjugate (AC) PDI agent against interleukin-5 receptor α-subunit (IL-5Rα)-positive MIBC cells. IL-5Rα is overexpressed on MIBC cells relative to superficial bladder cancer or healthy bladder cells. We selected a class of fluorescent dyes termed BODIPY for its availability, facile coupling to proteins, and easy chemical modifications to accommodate required absorption and fluorescence properties. BODIPY was attached to an AC composed of the antibody A14 functionalized with a moiety termed ChAcNLS, which we have shown enables it to escape endosome entrapment and redirect its trafficking to the nucleus. This novel approach results in increased intracellular accumulation of attached molecular payloads in MIBC cells. We aim to determine if ChAcNLS-A14 will increase intracellular accumulation of BODIPY to enhance fluorescence detection of MIBC by probe-based confocal laser endomicroscopy (pCLE). In addition, we aim to develop in an improved orthotopic rat bladder tumor model of human MIBC for testing. Methods We have prepared a carboxyl BODIPY derivative (B105) that allows for facile coupling to A14-ChAcNLS using routine procedures and reagents. The number of B105 and ChAcNLS per A14 was determined by fluorescence spectroscopy and SDS-PAGE, respectively. Intracellular accumulation of B105 was determined by treating HT1376 MIBC cells with A14-B105 and ChAcNLS-A14-B105. Cells were then imaged by fluorescence confocal microscopy. For the in vivo model of MIBC, RNU rats were anesthetized and their bladder washed in mild acid to disrupt the endothelium. HT1376 cells marked with the fluorescent marker DiL and instilled in the rat bladder. Intravesical pCLE was performed 2 weeks later. Results ChAcNLS-A14-B105 conjugate contained 7 molecules of B105 and 3 ChAcNLS peptides per A14. Confocal microscopy revealed the level of B105 intracellular accumulation in IL-5Rα-positive MIBC cells was increase ≥10-fold with ChAcNLS-A14-B105 relative to A14-B105. pCLE revealed HT1376 cells survived and colonized the rat bladder urothelium. Conclusion ChAcNLS-A14-B105 was successfully constructed and shown to significantly enhance B105 intracellular accumulation in target IL-5Rα-positive MIBC cells. A novel orthotopic rat bladder tumor model of human MIBC was also generated. Future testing of ChAcNLS-A14-B105 administered intravesically in RNU rat bladders bearing orthotopic tumors of human MIBC will be performed to determine the potential clinical translation of this new FI agent. Citation Format: Laurent Fafard-Couture, Simon Beaudoin, Samira Osati, Véronique Dumoulon-Perreault, Réjean Lebel, Brigitte Guérin, Johan E. van Lier, Jeffrey Leyton. ChAcNLS-A14-B105, a novel fluorescence imaging agent for enhanced detection of muscle invasive bladder cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4243.

Bombesin (BBN)-based radiolabeled peptides exhibit promising properties for targeted imaging of gastrin-releasing peptide receptors (GRPR)-positive tumors. The aim of this study was to evaluate with positron emission tomography (PET) the pharmacokinetic and imaging properties of two novel BBN-based radiolabeled peptides, (64)Cu/and (68)Ga/NOTA-PEG-BBN(6-14), for diagnosis of breast and prostate cancers using small animal models. Competitive binding assays on T47D breast and PC3 prostate cancer cells showed that the affinity for GRPR depends on the complexed metal and can vary up to a factor of about 3; (64)Cu/NOTA-PEG-BBN(6-14) was found to have the lowest inhibition constant (1.60 ± 0.59 nM). (64)Cu/and (68)Ga/NOTA-PEG-BBN(6-14) presented similar cell uptake on T47D and PC3 cells and were stable in vivo. Biodistribution studies of radiolabeled peptides carried out in Balb/c and tumor-bearing Balb/c nude mice showed that (64)Cu/NOTA-PEG-BBN(6-14) presented higher GRPR-mediated uptake in pancreas and adrenal glands, but comparable PC3 tumor uptake as (68)Ga/NOTA-PEG-BBN(6-14). Finally, receptor-dependent responses were observed during blocking studies with unlabeled peptide in both biodistribution and small-animal PET imaging studies. Our results confirmed the dependence of the affinity and pharmacokinetics of BBN-based radiopeptides on the complexed radiometal. Interspecies differences between mouse and human GRPR binding properties were also noted in these preclinical studies. Considering their good imaging characteristics, both (64)Cu/NOTA-PEG-BBN(6-14) and (68)Ga/NOTA-PEG-BBN(6-14) are promising candidates for GRPR-targeted PET imaging of breast and prostate cancers.

The synthesis of model heptapeptides bearing a host and a guest side chains at different positions is reported. These peptidic structures were designed in such a way that specific backbone conformations could be induced and stabilized by cooperative side chain interactions. Although circular dichroism studies demonstrated that intra- and intermolecular host guest interactions are involved in the stabilization of the peptidic conformation, they are not strong enough to induce a complete conformational reorganization.

Nucleophilic incorporation of [(18)F]F(-) under aqueous conditions holds several advantages in radiopharmaceutical development, especially with the advent of complex biological pharmacophores. Sulfonyl fluorides can be prepared in water at room temperature, yet they have not been assayed as a potential means to (18)F-labelled biomarkers for PET chemistry. We developed a general route to prepare bifunctional 4-formyl-, 3-formyl-, 4-maleimido- and 4-oxylalkynl-arylsulfonyl [(18)F]fluorides from their sulfonyl chloride analogues in 1:1 mixtures of acetonitrile, THF, or tBuOH and Cs[(18)F]F/Cs(2)CO(3(aq.)) in a reaction time of 15 min at room temperature. With the exception of 4-N-maleimide-benzenesulfonyl fluoride (3), pyridine could be used to simplify radiotracer purification by selectively degrading the precursor without significantly affecting observed yields. The addition of pyridine at the start of [(18)F]fluorination (1:1:0.8 tBuOH/Cs(2)CO(3(aq.))/pyridine) did not negatively affect yields of 3-formyl-2,4,6-trimethylbenzenesulfonyl [(18)F]fluoride (2) and dramatically improved the yields of 4-(prop-2-ynyloxy)benzenesulfonyl [(18)F]fluoride (4). The N-arylsulfonyl-4-dimethylaminopyridinium derivative of 4 (14) can be prepared and incorporates (18)F efficiently in solutions of 100 % aqueous Cs(2)CO(3) (10 mg mL(-1)). As proof-of-principle, [(18)F]2 was synthesised in a preparative fashion [88(±8) % decay corrected (n=6) from start-of-synthesis] and used to radioactively label an oxyamino-modified bombesin(6-14) analogue [35(±6) % decay corrected (n=4) from start-of-synthesis]. Total preparation time was 105-109 min from start-of-synthesis. Although the (18)F-peptide exhibited evidence of proteolytic defluorination and modification, our study is the first step in developing an aqueous, room temperature (18)F labelling strategy.

OBJECTIVE Postprandial plasma nonesterified fatty acid (NEFA) appearance is increased in type 2 diabetes. Our objective was to determine whether skeletal muscle uptake of plasma NEFA is abnormal during the postprandial state in type 2 diabetes. RESEARCH DESIGN AND METHODS Thigh muscle blood flow and oxidative metabolism indexes and NEFA uptake were determined using positron emission tomography coupled with computed tomography (PET/CT) with [11C]acetate and 14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid (18FTHA) in seven healthy control subjects (CON) and seven subjects with type 2 diabetes during continuous oral intake of a liquid meal to achieve steady postprandial NEFA levels with insulin infusion to maintain similar plasma glucose levels in both groups. RESULTS In the postprandial state, plasma NEFA level was higher in type 2 diabetic subjects versus CON (P < 0.01), whereas plasma glucose was at the same level in both groups. Muscle NEFA fractional extraction and blood flow index levels were 56% (P < 0.05) and 24% (P = 0.27) lower in type 2 diabetes, respectively. However, muscle NEFA uptake was similar to that of CON (quadriceps femoris [QF] 1.47 ± 0.23 vs. 1.37 ± 0.24 nmol ⋅ g−1 ⋅ min−1, P = 0.77; biceps femoris [BF] 1.54 ± 0.26 vs. 1.46 ± 0.28 nmol ⋅ g−1 ⋅ min−1, P = 0.85). Muscle oxidative metabolism was similar in both groups. Muscle NEFA fractional extraction and blood flow index were strongly and positively correlated (r = 0.79, P < 0.005). CONCLUSIONS Postprandial muscle NEFA uptake is normal despite elevated systemic NEFA levels and acute normalization of plasma glucose in type 2 diabetes. Lower postprandial muscle blood flow with resulting reduction in muscle NEFA fractional extraction may explain this phenomenon.

The synthesis of model heptapeptides bearing a host and a guest side chains at different positions is reported. These peptidic structures were designed in such a way that specific backbone conformations could be induced and stabilized by cooperative side chain interactions. Although circular dichroism studies demonstrated that intra- and intermolecular host guest interactions are involved in the stabilization of the peptidic conformation, they are not strong enough to induce a complete conformational reorganization.

The diastereoselectivity of radical processes involving 1,3-diols is increased significantly with a simple and efficient strategy using the exocyclic effect. Boronate derivatives are successfully formed in situ by treatment of an equimolar amount of Et3B in the presence of oxygen. This step is followed by the mediation of a carbon-centered radical α to the cyclic boronate to give the anti reduced product with high stereocontrol. The sequence is also extended to β-amino alcohols.

Reported herein is the iteration of a strategy employing a Mukaiyama reaction in tandem with a hydrogen transfer reaction for the elaboration of four polypropionate motifs containing the anti – anti unit. In this process, Lewis acid acts as the key element in controlling the diastereoselectivity of each step, the outcome of which is >20:1 for all of the reactions performed.

A convenient approach to functionalize peptides either at the N-terminal or on a lysine side chain with 1,4,7-triazacyclononane-N,N',N''-triacetic acid (NOTA) chelating unit has been developed on solid support. The chelate was assembled in a two-step process starting with bromo-acetylated peptides. Deprotection and cleavage of the resin-bound NOTA peptides were performed with use of trifluoroacetic acid (TFA) in the presence of thioanisole and water to give free NOTA peptides.

We designed and synthesized a novel contrast agent (CA) to image the activity of matrix metalloproteinase-2 (MMP-2) in a tumor, noninvasively using magnetic resonance imaging (MRI). We exploited the concept of solubility-switchable CAs in the design of a protease-modulated CA (PCA), referred to as PCA2-switch. This PCA contains a paramagnetic gadolinium chelate (Gd-DOTA), which was attached to the N-terminus of a MMP-2 cleavable peptide sequence via a hydrophobic chain. The aqueous solubility of the CA depends on the presence of a polyethylene glycol chain (PEG) on the C-terminus of the peptide. Upon proteolytic cleavage of the peptide by MMP-2, the PEG chain is detached from the CA, which becomes less water soluble. This compound and control compounds were successfully tested in an animal model bearing two tumors with different levels of MMP-2 activity.

The proprotein convertase PACE4 is strongly overexpressed in prostate cancer and plays an important role in tumor progression by promoting cell proliferation and tumor angiogenesis. Because the high expression levels and the necessity of this enzyme for cancer progression, we have developed a peptide-based inhibitor known as the Multi-Leucine (ML) peptide, which is a PACE4-specific inhibitor. Just like PACE4-downregulation through stable shRNA transfections, this compound displays anti-proliferative properties when applied on cancer cells. We showed its target-specific uptake into prostate cancer xenografts by positron emission tomography, which allowed clear tumor visualization. The ML-peptide has potent effects to block the further progression of prostate cancer cells, however, the uptake mechanism of this peptide is not clear and whether it is PACE4-dependent. We therefore tested the uptake and efflux rates of the ML-peptide peptide in prostate cancer cells and correlated these with PACE4 expression levels in wild type and stable PACE4-knockdown cell lines. In addition to prostate cancer cell lines LNCaP, DU145 and PC3, we tested HepG2, Huh7 and HT1080 cells, which also express PACE4. To measure peptide uptake, the ML peptide was modified through the addition a 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) moiety to strongly chelate radiometal such as 64Cu. Our study shows that uptake of the ML-peptide is correlated with expression levels, but more importantly can be blocked in PACE4-knockdown cell lines, demonstrating a PACE4-dependant uptake mechanism. We also correlated uptake with the anti-proliferative effects of the ML-peptide and showed that entry into these cell lines predicted the effects of the ML-peptide on the growth of these cells. These results confirm the notion that ML-peptide entry within cell is an important requirement to exert growth inhibition properties, and further provide a mechanism for that entry. This study demonstrates further support for the use of the ML-peptide or its analogs as potential drugs in prostate cancer, as well as any other PACE4-dependent tumors. These indications of peptide uptake within tumor could allows PACE4-status to be determined by positron emission tomography and may be of great theranostics uses in the context of pharmacological intervention with PACE4 inhibitors. Citation Format: Frédéric Couture, Kevin Ly, Christine Levesque, Anna Kwiatkowska, Roxane Desjardins, Brigitte Guérin, Robert Day. PACE4-dependent cellular uptake and retention of the Multi-Leucine peptide inhibitor into cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1707. doi:10.1158/1538-7445.AM2015-1707

Reported herein is a strategy employing a Mukaiyama reaction in tandem with a free radical-based allyl transfer reaction for the elaboration of functionalized tertiary and quaternary centers. The appropriate choice of alcohol-protecting group on the starting alpha-methyl-beta-hydroxyaldehyde and the nature of the Lewis acid used in the Mukaiyama reaction provided access to 3,4-anti and 3,4-syn aldolization products, precursors of the free-radical allylation reaction. After migration or exchange of the Lewis acid, the allyl transfer reaction with allyltributylstannane is then performed by taking advantage of the endocyclic effect, leading to the 2,3-anti relative stereochemistry. Importantly, (13)C NMR studies of the chelated intermediates are also reported and provide additional support for the endocyclic effect. In some cases, the remarkable reactivity of the aluminum-based Lewis acids allowed the use of allyltrimethylsilane, an interesting reagent from an ecological standpoint. The isolation of a key intermediate is also indicative of an atom transfer mechanism when the silicon-based reagent is employed.

Presence of endosome-disrupting multiple histidine functionalities in the molecular architecture of cationic polymers, such as polylysine, has previously been demonstrated to significantly enhance their in vitro gene delivery efficiencies. Towards harnessing improved transfection property through covalent grafting of endosome-disrupting single histidine functionality in the molecular structure of cationic lipids, herein, we report on the design, the synthesis and the transfection efficiency of two novel nonglycerol-based histidylated cationic amphiphiles. We found that L-histidine-(N,N-di-n-hexadecylamine)ethylamide (lipid 1) and L-histidine-(N,N-di-n-hexadecylamine,-N-methyl)ethylamide (lipid 2) in combination with cholesterol gave efficient transfections into various cell lines. The transfection efficiency of Chol/lipid 1 lipoplexes into HepG2 cells was two order of magnitude higher than that of FuGENE(TM)6 and DC-Chol lipoplexes, whereas it was similar into A549, 293T7 and HeLa cells. A better efficiency was obtained with Chol/lipid 2 lipoplexes when using the cytosolic luciferase expression vector (pT7Luc) under the control of the bacterial T7 promoter. Membrane fusion activity measurements using fluorescence resonance energy transfer (FRET) technique showed that the histidine head-groups of Chol/lipid 1 liposomes mediated membrane fusion in the pH range 5-7. In addition, the transgene expression results using the T7Luc expression vector convincingly support the endosome-disrupting role of the presently described mono-histidylated cationic transfection lipids and the release of DNA into the cytosol. We conclude that covalent grafting of a single histidine amino acid residue to suitable twin-chain hydrophobic compounds is able to impart remarkable transfection properties on the resulting mono-histidylated cationic amphiphile, presumably via the endosome-disrupting characteristics of the histidine functionalities.

The weak efficiency of plasmid transfer into the cytosol remains one of the major limiting factors to achieve an efficient transfection with DNA/cationic polymer complexes. We found that divalent metal Zn2+ can improve the polyfection efficiency, especially with DNA/histidylated polylysine (His-pLK) complexes.The supplementation of the transfection medium with 250 micro M ZnCl2 increased the polyfection of human hepatocarcinoma (HepG2) cells with a plasmid encoding EGFP complexed with pLK, polyethyleneimine and His-pLK. Zn2+ is more efficient on DNA/His-pLK complexes: the number of EGFP-positive cells increased from 1% to more than 40%. This phenomenon is selective to Zn2+ because no effect was obtained with other divalent cations. The effect of zinc varies from cell to cell. The binding of Zn2+ to histidyl residues might increase zinc endosomal concentration favoring membrane fusion. Flow cytometry and confocal microscopy studies clearly indicate that with His-pLK, the plasmid is better delivered in the cytosol as well as in the cell nucleus in zinc-treated cells. An investigation conducted with the histidine-rich peptide H5WYG showed that zinc inhibits membrane permeabilization but promotes membrane fusion as evidenced by resonance energy transfer.Data reported here imply that the addition of zinc ions in the transfection medium can trigger an increase of the fusion of endosomes containing polyplexes which is more effective in the presence of histidine-rich molecules. Consequently, the amount of plasmid in the cytosol available to reach the nucleus is increased leading to an improvement of polyfection.

[reaction: see text] Reported herein is a strategy employing a Mukaiyama reaction in tandem with a hydrogen transfer reaction for the elaboration of 2,3-anti-3,4-anti and 2,3-anti-3,4-syn propionate motifs. The mode of complexation is controlled through monodentate or chelate pathways for the Mukaiyama reaction to give access to either syn or anti aldol products, precursors of the free-radical reduction reaction. Boron Lewis acid is used to control the free-radical reaction through the exocyclic pathway.

[reaction: see text] Acyclic diastereoselection is achieved for the formation of thioaminyl acetals. The highly intramolecular stereocontrolled S(N)2 displacement of the thioaminyls allows for the formation of cyclic nucleoside derivatives. This versatile approach may provide easy access to a large variety of N-glycosides.

International audience; Polyplexes of high stability resulting from the condensation of a plasmid DNA by a cationic polymer are widely used to develop polymer-based gene delivery systems. However, the plasmid must be released from its vector once inside the cells for an efficient expression of the exogenous gene in the cell nucleus. We have designed a disulfide-containing cationic polymer termed poly[Lys-(AEDTP)] which allowed for the formation of polyplexes and the release of the plasmid in a reductive medium. The amino groups of polylysine were substituted with 3-(2-aminoethyldithio)propionyl residues in order to have each amino group of poly[Lys-(AEDTP)] interacting with a phosphate DNA linked to the polymer backbone via a disulfide bond. As evidenced by agarose gel electrophoresis and ethidium bromide/pDNA fluorescence restoration, poly[Lys-(AEDTP)] polyplexes were decondensed and the plasmid released upon treatment with either dithiothreitol, glutathione in the presence of glutathione reductase, or the thioredoxin reductase. Electron microscopy showed that polyplexes exhibiting spherical particles of a mean size at about 100 nm were decondensed in the presence of glutathione and exhibited filamentous aggregates. Finally, we found that the transfection of 293T7 and HepG2 cells was 10- and 50-fold more efficient with poly[Lys-(AEDTP)] polyplexes, respectively, than with poly[Lys] polyplexes. These results indicate that disulfide-containing cationic polymers must be borne in mind for developing polymer-base gene delivery systems.

Introduction La barriere hemato-encephalique (BHE) de par sa presence limite l’acheminement d’agents therapeutiques au systeme nerveux central (SNC). La presence de pompes a efflux au niveau de la BHE constitue un important mecanisme d’exclusion d’agents lipophiles tentant t’atteindre le SNC. La glycoproteine-P (p-gp), l’une de ses pompes a efflux, est exprimee a la BHE et par les cellules tumorales et a pour substrats plusieurs agents de chimiotherapie. Il a ete demontre que l’ouverture osmotique de la BHE (OBHE) est efficace pour acheminer des agents n’etant pas des substrats de la PGP. Cependant, il n’a pas ete demontre que l’OBHE permet d’augmenter egalement l’acheminement d’agents antineoplasiques substrats de la PGP. Cette etude a ete mise sur pied afin de determiner si l’OBHE permet d’augmenter l’acheminement de substrats de la PGP. Materiels et methode Trois groupes d’animaux etaient a l’etude : 1 : OBHE, 2 : temoin positif (Tariquidar, inhibiteur specifique de la PGP), 3 : radiotraceur seul, a raison de 6 animaux par groupe. Le 11C-carvedilol, substrat de la PGP, a ete administre durant la 1re minute de l’acquisition par tomographie d’emission par positrons. La captation du 11C-carvedilol a ete calculee pour deux regions d’interets : le volume tumoral et un volume equivalent dans l’hemisphere controlateral. Resultats Aucune difference significative n’a ete observee pour les courbes temps–activite dans l’hemisphere controlateral pour tous les groupes etudies. Il n’y a que dans le groupe 2 que la captation du 11C-carvedilol est augmentee au niveau de la tumeur. Ces resultats suggerent que l’OBHE n’affecte pas l’activite de la PGP. Conclusion Si ces resultats se confirment, la procedure d’OBHE ne serait pas utile lorsque son utilisation est combinee a l’administration d’agents therapeutiques substrats de les p-gp.

s / Can J Diabetes 38 (2014) 151e153 153 exposed to HG in normoxia (P1⁄40.0204 for PDGF) and in hypoxia. We observed that HG inhibited PDGF-induced vSMC migration, an effect that was amplifiedwhen exposed to hypoxia. Intriguingly, we did not observed any change in insulinor PDGF-stimulated Akt or ERK activation in cells treated with HG and/or hypoxia. In conclusion, hyperglycemia affects vSMC proliferation and migration in hypoxic condition. However, more experiments are needed to determine the mechanisms involved in this phenomenon. Funding: This work was supported by the Canadian association of diabetes (CDA) operating grant (P.G.). P.G is a recipient of a Canada Research Chair in Diabetes and Vascular Complications and Canadian Diabetes Association Scholar Award. M.P. is the recipient of a scholarship from Diabete Quebec.

Reported herein is a strategy employing a Mukaiyama reaction in tandem with a hydrogen transfer reaction for the elaboration of propionate motifs. The nature of the protecting groups on the chiral beta-alkoxy aldehyde and the type of Lewis acid used are varied to modulate the stereochemical outcome of the tandem reactions. The mode of complexation is thus controlled (monodentate or chelate) for the Mukaiyama reaction to give access to either syn or anti aldol products, precursors of the free radical reduction reaction. The endocyclic effect is subsequently capitalized upon to control the hydrogen transfer step so that the syn-reduced product may be achieved. Proceeding with excellent yield and diastereoselectivity, the synthetic sequence proposed gives access to syn-syn and syn-anti propionate motifs. Also considered is a complementary approach using a chelation-controlled Mukaiyama reaction in tandem with a free radical allylation reaction under the control of the endocyclic effect that leads to the anti-anti product.

The strategy considered herein features an iodocyclofunctionalization/hydrogen-transfer reaction sequence for the elaboration of propionate motifs. Proceeding with excellent yield and diastereoselectivity, the synthetic sequence proposed gives access to the anti-anti dipropionate motif when the reduction step is performed under the control of the exocyclic effect. The tandem sequence is applied successfully to the synthesis of the C(7)-C(16) subunit of zincophorin, and iteration of the process gives the desired anti-anti-anti-anti polypropionate stereopentad. Modifications of the reaction sequence--including phenylselenocyclofunctionalization, carbonate hydrolysis, and chelation-controlled radical reduction reactions--lead to the formation of the anti-syn dipropionate motif with remarkable diastereocontrol.

[structure in text] The diastereoselectivity of radical processes involving 1,3-diols is increased significantly with a simple and efficient strategy using the exocyclic effect. Boronate derivatives are successfully formed in situ by treatment of an equimolar amount of Et(3)B in the presence of oxygen. This step is followed by the mediation of a carbon-centered radical alpha to the cyclic boronate to give the anti reduced product with high stereocontrol. The sequence is also extended to beta-amino alcohols.

The synthesis, characteristics and recognition ability of a novel class of acyclic peptidic receptors designed to complex aromatic ammonium guests using a combination of hydrogen-bonding, electrostatic and π–π interactions is described.

The radical allylation of a series of α-halo or α-phenylseleno-β-alkoxy esters in the presence of MgBr2·OEt2 is reported and compared with analogous reactions under non-chelating conditions. The ad...