Plasma membrane lipid bilayer is druggable: Selective delivery of gemcitabine-squalene nano-medicine to cancer cells.

Up to now the lipid bilayers were rarely considered as targets in cancer therapy despite pronounced differences in lipid composition between plasma membranes of benign and malignant cells. In this study we demonstrate that the lipid bilayer of the plasma membrane is druggable and suitable for facilitating selective delivery of amphiphilic gemcitabine-squalene nanomedicines to cancer cells. Data from radioactive assays, fluorescent membrane probes and molecular dynamics simulations provide evidence of selective accumulation of gemcitabine-squalene in the plasma membranes with disrupted lipid asymmetry and its subsequent preferential uptake by malignant cells. This causes pronounced cytotoxicity on cancer cells in comparison to their benign counterparts originating from the same tissue.

Gemcitabine lipid prodrug nanoparticles: Switching the lipid moiety and changing the fate in the bloodstream.

A simple approach to achieve a lipoprotein (LP)-mediated drug delivery is to trigger the spontaneous drug insertion into endogenous lipoproteins in the bloodstream, by means of its chemical modification. Nanoparticles (NPs) made of the squalene-gemcitabine (SQGem) conjugate were found to have a high affinity for plasma lipoproteins while free gemcitabine did not, suggesting a key role of the lipid moiety in this event. Whether the drug conjugation to cholesterol, one of the major lipoprotein-transported lipids, could also promote an analogous interaction was a matter of question. NPs made of the cholesterol-gemcitabine conjugate (CholGem) have been herein thoroughly investigated for their blood distribution profile both in vitro and in vivo. Unexpectedly, contrarily to SQGem, no trace of the CholGem prodrug could be found in the lipoprotein fractions, nor was it interacting with albumin. The investigation of isolated NPs and NPs/LPs physical mixtures provided a further insight into the lack of interaction of CholGem NPs with LPs. Although essential for allowing the self-assembly of the prodrug into nanoparticles, the lipid moiety may not be sufficient to elicit interaction of the conjugated drug with plasma lipoproteins but the whole NP physicochemical features must be carefully considered.

Gemcitabine Lipid Prodrugs: The Key Role of the Lipid Moiety on the Self-Assembly into Nanoparticles.

A small library of amphiphilic prodrugs has been synthesized by conjugation of gemcitabine (Gem) (a hydrophilic nucleoside analogue) to a series of lipid moieties and investigated for their capacity to spontaneously self-assemble into nanosized objects by simple nanoprecipitation. Four of these conjugates formed stable nanoparticles (NPs), while with the others, immediate aggregation occurred, whatever the tested experimental conditions. Whether such capacity could have been predicted based on the prodrug physicochemical features was a matter of question. Among various parameters, the hydrophilic-lipophilic balance (HLB) value seemed to hold a predictive character. Indeed, we identified a threshold value which well correlated with the tendency (or not) of the synthesized prodrugs to form stable nanoparticles. Such a hypothesis was further confirmed by broadening the analysis to Gem and other nucleoside prodrugs already described in the literature. We also observed that, in the case of Gem prodrugs, the lipid moiety affected not only the colloidal properties but also the in vitro anticancer efficacy of the resulting nanoparticles. Overall, this study provides a useful demonstration of the predictive potential of the HLB value for lipid prodrug NP formulation and highlights the need of their opportune in vitro screening, as optimal drug loading does not always translate in an efficient biological activity.