In the domain of health, one important challenge is the efficient delivery of drugs in the body using non-toxic nanocarriers. Most of the existing carrier materials show poor drug loading (usually less than 5 wt% of the transported drug versus the carrier material) and/or rapid release of the proportion of the drug that is simply adsorbed (or anchored) at the external surface of the nanocarrier. In this context, porous hybrid solids, with the ability to tune their structures and porosities for better drug interactions and high loadings, are well suited to serve as nanocarriers for delivery and imaging applications. Here we show that specific non-toxic porous iron(III)-based metal-organic frameworks with engineered cores and surfaces, as well as imaging properties, function as superior nanocarriers for efficient controlled delivery of challenging antitumoural and retroviral drugs (that is, busulfan, azidothymidine triphosphate, doxorubicin or cidofovir) against cancer and AIDS. In addition to their high loadings, they also potentially associate therapeutics and diagnostics, thus opening the way for theranostics, or personalized patient treatments.

Nucleoside analogues display significant anticancer or antiviral activity by interfering with DNA synthesis. However, there are some serious restrictions to their use, including their rapid metabolism and the induction of resistance. We have discovered that the linkage of nucleoside analogues to squalene leads to amphiphilic molecules that self-organize in water as nanoassemblies of 100-300 nm, irrespective of the nucleoside analogue used. The squalenoyl gemcitabine exhibited superior anticancer activity in vitro in human cancer cells and gemcitabine-resistant murine leukemia cells, and in vivo in experimental leukemia both after intravenous and oral administration. The squalenoylation of other antiretroviral nucleosides also led to more potent drugs when tested in primary cultures of HIV-infected lymphocytes. Thus, the squalenoylation is an original technology platform for generating more potent anticancer and antiviral nanomedicines.

We have used an ultraviolet light cross-linking and immunoadsorption assay to demonstrate that histones H1 and H2B are bound to the repressed MMTV promoter. Hormone activation results in reduced H1 content with little or no change in H2B. High resolution analysis of the glucocorticoid-inducible DNaseI hypersensitive region demonstrates an NF-1 footprint as well as specific sites of enhanced cleavage on nucleosome B and in the nucleosome B/nucleosome A linker. These results are consistent with a model in which binding of the glucocorticoid receptor to glucocorticoid regulatory elements on the surface of nucleosome B induces a chromatin transition that is necessary for transcription factor (NF-1 and TFIID) recruitment to the MMTV promoter. We hypothesize that association of histone H1 with important cis-elements on the promoter masks these sites, and glucocorticoid-induced displacement of H1 is necessary to expose factor binding sites at the 3' edge of nucleosome B, in the nucleosome B/nucleosome A linker and at the 5' edge of nucleosome A.

YAP and its paralog protein TAZ are downstream effectors of the Hippo pathway. Both are amplified in many human cancers and promote cell proliferation and epithelial–mesenchymal transition. Little is known about the status of the Hippo pathway in cutaneous melanoma. We profiled Hippo pathway component expression in a panel of human melanoma cell lines and melanocytic lesions, and characterized the capacity of YAP and TAZ to control melanoma cell behavior. YAP and TAZ immuno-staining in human samples revealed mixed cytoplasmic and nuclear staining for both proteins in benign nevi and superficial spreading melanoma. TAZ was expressed at higher levels than YAP1/2 in all cell lines and in those with high invasive potential. Stable YAP or TAZ knockdown dramatically reduced the expression of the classical Hippo target CCN2/connective-tissue growth factor (CTGF), as well as anchorage-independent growth, capacity to invade Matrigel, and ability form lung metastases in mice following tail-vein injection. YAP knockdown also reduced invasion in a model of skin reconstruct. Inversely, YAP overexpression increased melanoma cell invasiveness, associated with increased TEA domain–dependent transcription and CCN2/CTGF expression. Together, these results demonstrate that both YAP and TAZ contribute to the invasive and metastatic capacity of melanoma cells and may represent worthy targets for therapeutic intervention.

Estrogen receptor-alpha (ER) is down-regulated in the presence of its cognate ligand, estradiol (E2), as well as in the presence of antiestrogens, through the ubiquitin proteasome pathway. Here, we show that, at pharmacological concentrations, the degradation rate of pure antagonist/endogenous ER complexes from human breast cancer MCF-7 cells is 10 times faster than that of ER-E2 complexes, while 4-hydroxy-tamoxifen (4-OH-T)-ER complexes are stable. Whereas pure antagonist-ER complexes are firmly bound to a nuclear compartment from which they are not extractable, the 4-OH-T-ER accumulates in a soluble cell compartment. No difference was observed in the fate of ER whether bound to pure antiestrogens ICI 182,780 or RU 58668. Cycloheximide experiments showed that, while the proteasome-mediated destruction of E2-ER (unlike that of RU 58668- and ICI 182,780-ER) complexes could implicate (or not) a protein synthesis-dependent process, both MAPKs (p38 and ERKs p44 and p42) are activated. By using a panel of kinase inhibitors/activators to study the impact of phosphorylation pathways on ER degradation, we found that protein kinase C is an enhancer of proteasome-mediated degradation of both ligand-free and ER bound to either E2, 4-OH-T, and pure antagonists. On the contrary, protein kinase A, MAPKs, and phosphatidyl-inositol-3 kinase all impede proteasome-mediated destruction of ligand free and E2-bound ER while only MAPKs inhibit the degradation of pure antiestrogens/ER species. In addition, no correlation was found between the capacity of kinase inhibitors to affect ER stability and the basal or E2-induced transcription. These results suggest that, in MCF-7 breast cancer cells, ER turnover, localization, and activity are maintained by an equilibrium between various phosphorylation pathways, which are differently modulated by ER ligands and protein kinases.

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No abstract

Cationic hyaluronic acid (HA)-modified DOTAP/DOPE liposomes were designed for the targeted delivery of anti-telomerase siRNA to CD44 receptor-expressing lung cancer cells. DOTAP/DOPE liposomes modified with 1%-20% (w/w) HA-DOPE conjugate were obtained by the ethanol injection method. Their size was below 170 nm and they exhibited zeta potentials higher than +50 mV. Lipoplexes prepared at different +/-ratios with siRNA were in the range of 200 nm and below and their zeta potentials were strongly dependent on the degree of modification and the +/-charge ratio. The presence of HA did not compromise binding, protection of siRNA from degradation, and complex stabilities in serum but rather resulted in an improvement of these properties. Liposome cytotoxicity, investigated by the MTT assay and LDH release after treatment of CD44(+) A549 cells and CD44(-) Calu-3, was demonstrated only at high concentrations. However, the addition of siRNA to HA-modified liposomes prevented cytotoxic effects compared to all other formulations. As shown by flow cytometry, transfection of siRNA into A549 cells was markedly improved with HA-modified liposomes, but not into Calu-3 cells. Using a qPCR-TRAP assay to test telomerase activity, no difference was demonstrated in the efficiency between HA-modified and nonmodified preparations. Moreover, some reduction in telomerase activity was observed with liposomes alone, lipoplexes prepared with nonsense siRNA and lipofectamine, indicative for some direct inhibitory effect of the lipids and siRNA on the expression of this enzyme. HA-modified DOTAP/DOPE liposomes represent a suitable carrier system for siRNA since properties like binding or protection of siRNA are not altered. They display an improved stability in cell culture medium and a reduced cytotoxicity. Furthermore, these novel lipoplexes could successfully be targeted to CD44-expressing A549 cells opening interesting perspectives for the treatment of lung cancer.