A ß-Cyclodextrin-Based Nanoparticle with Very High Transfection Efficiency Unveils siRNA-Activated TLR3 Responses in Human Prostate Cancer Cells.

Synthetic double-stranded small interfering RNAs (siRNAs) mimic interference RNAs (RNAi) and can bind target mRNAs with a high degree of specificity, leading to selective knockdown of the proteins they encode. However, siRNAs are very labile and must be both protected and transported by nanoparticles to be efficiently delivered into cells. In this work, we used a Janus-type polycationic amphiphilic ß-cyclodextrin derivative to efficiently transfect siRNAs targeting mRNAs encoding mitogen-activated protein kinase (p42-MAPK) or Ras homolog enriched in brain (Rheb) into different cancer cell lines as well as astrocytes. We took advantage of this high transfection efficiency to simultaneously knock down p42-MAPK and Rheb to boost docetaxel (DTX)-mediated toxicity in two human prostate cancer cell lines (LNCaP and PC3). We found that double knockdown of p42-MAPK and Rheb increased DTX-toxicity in LNCaP but not in PC3 cells. However, we also observed the same effect when scramble siRNA was used, therefore pointing to an off-target effect. Indeed, we found that the siRNA we used in this work induced toll-like receptor 3 activation, leading to ß-interferon production and caspase activation. We believe that this mechanism could be very useful as a general strategy to elicit an immune response against prostate cancer cells.

Mannosyl-coated nanocomplexes from amphiphilic cyclodextrins and pDNA for site-specific gene delivery.

Fully homogeneous facial amphiphiles consisting in a cyclodextrin (CD) platform onto which a polycationic cluster and a multi-tail hydrophobic moiety have been installed (polycationic amphiphilic CDs; paCDs) self-organized in the presence of plasmid DNA to form nanometric complexes (CDplexes) which exhibit broad-range transfection capabilities. We hypothesized that biorecognizable moieties located at the hydrophilic rim in the CD scaffold would be exposed at the surface of the corresponding nanoparticles after DNA-promoted aggregation, endowing the system with molecular recognition abilities towards cell receptors. This concept has been demonstrated by developing an efficient synthetic strategy for the preparation of multivalent polycationic glyco-amphiphilic CDs (pGaCDs). Self-assembled nanoparticles obtained from mannosylated pGaCDs and pDNA (average hydrodynamic diameter 80 nm) have been shown to be specifically recognized by mannose-specific lectins, including concanavalin A (Con A) and the human macrophage mannose receptor (MMR). Further macrophage adhesion studies indicated that unspecific binding, probably due to electrostatic interactions with negatively charged cell membrane components, can also operate. The relative specific versus non-specific internalization is dependent on the pGaCD:pDNA proportion, being optimal at a protonable nitrogen/phosphate (N/P) ratio of 5. The resulting GlycoCDplexes were shown to specifically mediate transfection in Raw 264.7 (murine macrophage) cells expressing the mannose-fucose receptor in vitro. FACS experiments confirmed that transfection using these nanoparticles is mannose-dependent, supporting the potential of the approach towards vectorized gene delivery.

Comparative studies on lectin-carbohydrate interactions in low and high density homo- and heteroglycoclusters.

A versatile synthetic procedure to construct series of high- and low-density homo- and heteroglycoclusters is reported. The binding properties of these synthetic multivalent glycoconjugates to concanavalin A (Con A), a model lectin, have been assessed by using a range of competitive and non-competitive binding assays including enzyme-linked lectin assays (ELLA), isothermal titration microcalorimetry (ITC) and surface plasmon resonance (SPR). In all cases, highly dense glycoclusters showed a substantial amplification of the lectin-binding strength in comparison with low-density counterparts. Interestingly, highly-dense glycoligand presentations, regardless of their homo- or heteroglycoligand pattern, furnished similar Con A binding properties, supporting the existence of a synergic effect (heterocluster effect) due to secondary interactions of "non-active" structural motifs in the presence of a certain density of "active" glycoligands.

Synthesis of alpha- and beta-glycosyl isothiocyanates via oxazoline intermediates.

A practical synthesis of acylated glycosyl isothiocyanates from sugar oxazolines, by reaction with thiophosgene, is reported. In the absence of any additive, the reaction is governed by the reverse anomeric effect, leading to the equatorially oriented isothiocyanate. However, in the presence of copper(II) chloride, the reaction proceeds preferentially with retention of the configuration at the anomeric center, providing the axial anomer as the major product. Noteworthy, this strategy allows accessing per-O-acetylated glycopyranosyl isothiocyanates with 1,2-cis relative configuration (e.g., the alpha-anomer in the D-gluco and D-galacto series), a problem that was outside the scope of previous methodologies.