Targeted Shiga toxin-drug conjugates prepared via Cu-free click chemistry.

The main drawback of the anticancer chemotherapy consists in the lack of drug selectivity causing severe side effects. The targeted drug delivery appears to be a very promising strategy for controlling the biodistribution of the cytotoxic agent only on malignant tissues by linking it to tumor-targeting moiety. Here we exploit the natural characteristics of Shiga toxin B sub-unit (STxB) as targeting carrier on Gb3-positive cancer cells. Two cytotoxic conjugates STxB-doxorubicin (STxB-Doxo) and STxB-monomethyl auristatin F (STxB-MMAF) were synthesised using copper-free 'click' chemistry. Both conjugates were obtained in very high yield and demonstrated strong tumor inhibition activity in a nanomolar range on Gb3-positive cells.

SNAP-tag based proteomics approach for the study of the retrograde route.

Proteomics is a powerful technique for protein identification at large scales. A number of proteomics approaches have been developed to study the steady state composition of intracellular compartments. Here, we report a novel vectorial proteomics strategy to identify plasma membrane proteins that undergo retrograde transport to the trans-Golgi network (TGN). This strategy is based on the covalent modification of the plasma membrane proteome with a membrane impermeable benzylguanine derivative. Benzylguanine-tagged plasma membrane proteins that are subsequently targeted to the retrograde route are covalently captured by a TGN-localized SNAP-tagged fusion protein, which allows for their identification. The approach was validated step-by-step using a well explored retrograde cargo protein, the B-subunit of Shiga toxin. It was then extended to the proteomics format. Among other hits we found one of the historically first identified cargo proteins that undergo retrograde transport, which further validated our approach. Most of the other hits were kinases, receptors or transporters. In conclusion, we have pioneered a vectorial proteomics approach that complements traditional methods for the study of retrograde protein trafficking. This approach is of generic nature and could in principle be extended to other endocytic pathways.

A new access to 3-substituted-1(2H)-isoquinolone by tandem palladium-catalyzed intramolecular aminocarbonylation annulation.

An original tribromide derivative based, palladium-catalyzed synthesis of 3-substituted-1(2H)-isoquinolone is described based on a regioselective Suzuki-Miyaura C-C coupling on o-halo-(2,2-dihalovinyl)-benzene followed by a palladium catalyzed amination-carbonylation-cyclization reaction. This sequence efficiently proceeds to build up isoquinolone in fair to good yields over a one-pot 3-bond synthesis reaction.

Chemistry-based protein modification strategy for endocytic pathway analysis.

BACKGROUND INFORMATION: The integrated analysis of intracellular trafficking pathways is one of the current challenges in the field of cell biology, and functional proteomics has become a powerful technique for the large-scale identification of proteins or lipids and the elucidation of biological processes in their natural contexts. For this, new dynamic strategies must be devised to trace proteins that follow a specific pathway such that their initial and final destinations can be detected by automated means. RESULTS: Here, we report a novel vectorial strategy for trafficking pathway analysis. This strategy is based on a chemical modification of plasma membrane proteins with a bSuPeR (biotinylated sulfation site peptide reagent) and metabolic labelling in the Golgi apparatus, such that plasma membrane proteins that traffic via the retrograde route become detectable in complex mixtures. Efficient synthesis schemes are presented for tailor-made chemical tools that are then applied to the step-by-step validation of the strategy, using a known retrograde cargo protein: the STxB (Shiga toxin B-subunit). bSuPeR modification at the plasma membrane does not affect STxB transport to the Golgi apparatus, where the protein is metabolically labelled, allowing its detection in cell lysates. CONCLUSIONS: Our vectorial concept proposes a new chemical approach for traffic-based profiling of proteins that may prove to be applicable to the analysis of diverse endocytic pathways.

New synthetic glycolipids for targeted gene transfer: synthesis, formulation in lipoplexes and specific interaction with lectin.

Nonviral gene delivery systems are a promising approach for gene therapy applications, despite their low in vivo gene transfer efficiency. One approach to enhance this efficiency is to incorporate targeting elements into cationic lipid/DNA complexes (lipoplexes). Ligand-containing lipoplexes have to retain their efficiency while exposing accessible ligand on their surface. Physicochemical properties (particle size, surface charge, and efficacy of DNA complexation) of the lipoplexes largely determine their gene transfer efficiency. We synthesized glycolipids with various galactosylated head ligand and incorporated them into lipoplexes. We showed that incorporation of up to 33% mol of glycolipid did not change the physicochemical properties of lipoplexes. Some of our glycolipids yielded lipoplexes whose galactosyl heads were well exposed on the surface as demonstrated by a strong interaction with Ricinus communis agglutinin. Glycolipid-containing lipoplexes gave an efficient gene transfer on hepatocytes, although no ligand-targeted transfection could be observed.

A new drug-release method using the Staudinger ligation.

Many drugs induce severe side-effects caused by their lack of selectivity. One way to overcome this problem is to design a specific system which releases a free drug in a controlled manner. Herein we describe a new way to liberate a drug from a prodrug using the Staudinger ligation as the trigger.