Apoferritin encapsulation of cysteine protease inhibitors for cathepsin L inhibition in cancer cells

Cysteine proteases play a key role in tumorigenesis causing protein degradation and promoting invasive tumour growth. Cathepsin L is overexpressed in cancer cells and could provide a specific target for delivery of anticancer agents. We encapsulated novel dipeptidyl nitrile based cysteine protease inhibitors (Neq0551, Neq0554 and Neq0568) into biocompatible apoferritin (AFt) protein nanocages to achieve specific delivery to tumours and pH-induced drug release. AFt-encapsulated Neq0554 demonstrated $3-fold enhanced in vitro activity (GI 50 ¼ 79 mM) compared to naked agent against MiaPaCa-2 pancreatic carcinoma cells. Selectivity for cancer cells was confirmed by comparing their activity to non-tumourigenic human fibroblasts (GI 50 > 200 mM). Transferrin receptor (TfR-1) expression, detected only in lysates prepared from carcinoma cells, may contribute to the cancer-selectivity. The G 1 cell cycle arrest caused by AFt-Neq0554 resulting in cytostasis was corroborated by clonogenic assays. Superior and more persistent inhibition of cathepsin L up to 80% was achieved with AFt-encapsulated agent in HCT-116 cells following 6 h exposure to 50 mM agent. The selective anticancer activity of AFt-encapsulated cysteine protease inhibitor Neq0554 reported here warrants further preclinical in vivo evaluation

Modulation of the activity and selectivity of the immobilized lipases by surfactants and solvents

Most of lipases are in equilibrium between a majority inactive closed form and a minority active open form in aqueous media. Perhaps, a certain stabilization of these open forms of lipases could be achieved in the presence of cosolvents or surfactants in the reaction medium. Three commercial lipases were studied (from Thermomyces lanuginosa (TLL), Candida Antarctica fraction B (CALB) and Lecitase (LEC)). Different derivatives were tested: TLL and LEC were adsorbed on an anionic exchanger and their activity strongly depends on the equilibrium between their open and closed form and CALB was adsorbed on a hydrophobic support when the open form was already stabilized by the support. Derivatives ionically adsorbed were hyperactivated by surfactans as well as by cosolvents: the activity of LEC increased 12 times in the presence of 15-20% of ethanol. CALB adsorbed on hydrophobic supports was hardly hyperactivated and even it was inhibited. The modification of the rate of covalent modification of the catalytic Ser seems to confirm that the observed hyperactivations were due to a stabilization of the open form of the adsorbed lipases (TLL and LEC). The hydrolysis of sardine oil was also studied in the presence or absence of surfactants and cosolvents. An interesting improvement in the ability of derivatives to discriminate the release of eicosipentaenic acid (EPA) and docosahexaenicacid (DHA) was found.The authors thank the financial support of Coordination for the Improvement of Higher Level -or Education Personnel (CAPES) and São Paulo Research Foundation (FAPESP), grant 2013/00530-0.Peer Reviewe