Liposome-encapsulated prednisolone phosphate inhibits growth of established tumors in mice

Glucocorticoids can inhibit solid tumor growth possibly due to an inhibitory effect on angiogenesis. The antitumor effects of the free drugs have only been observed using treatment schedules based on high and frequent dosing for prolonged periods of time. As long-circulating liposomes accumulate at sites of malignancy, we investigated the tumor-inhibiting potential of liposome-encapsulated prednisolone phosphate. Liposomal prednisolone phosphate could inhibit tumor growth dose-dependently, with 80% to 90% tumor growth inhibition of subcutaneous B16.F10 melanoma and C26 colon carcinoma murine tumor models at 20 mg/kg by single or weekly doses. Prednisolone phosphate in the free form was completely ineffective at this low-frequency treatment schedule, even when administered at a dose of 50 mg/kg. In vitro studies did not show an inhibitory effect of prednisolone (phosphate) on tumor cell, nor on endothelial cell proliferation. Histologic evaluation revealed that liposomal prednisolone phosphate-treated tumors contained a center with areas of picnotic/necrotic cells, which were not apparent in untreated tumors or tumors treated with the free drug. In conclusion, the present study shows potent antitumor effects of liposomal formulations of glucocorticoids in a low dose and low-frequency schedule, offering promise for liposomal glucocorticoids as novel antitumor agents.</p

Involvement of the p62/NRF2 signal transduction pathway on erythrophagocytosis

This deposit is composed by the main article plus the supplementary materials of the publication.Erythrophagocytosis, the phagocytic removal of damaged red blood cells (RBC), and subsequent phagolysosome biogenesis are important processes in iron/heme metabolism and homeostasis. Phagolysosome biogenesis implies the interaction of nascent phagosomes with endocytic compartments and also autophagy effectors. Here, we report that besides recruitment of microtubule-associated protein-1-light chain 3 (LC3), additional autophagy machinery such as sequestosome 1 (p62) is also acquired by single-membrane phagosomes at very early stages of the phagocytic process and that its acquisition is very important to the outcome of the process. In bone marrow-derived macrophages (BMDM) silenced for p62, RBC degradation is inhibited. P62, is also required for nuclear translocation and activation of the transcription factor Nuclear factor E2-related Factor 2 (NRF2) during erythrophagocytosis. Deletion of the Nrf2 allele reduces p62 expression and compromises RBC degradation. In conclusion, we reveal that erythrophagocytosis relies on an interplay between p62 and NRF2, potentially acting as protective mechanism to maintain reactive oxygen species at basal levels and preserve macrophage homeostasis.Fundação para a Ciência e a Tecnologia grants: (HMSP-ICT/0024/2010, UID/Multi/04462/2013, SFRH/BD/62197/2009, SFRH/BD/90258/2012, SFRH /BD/51877/2012, SFRH/BD/52293/2013, PTDC/SAU-TOX/116627/2010, HMSP-ICT/0022/2010 ); European Union FEDER support: (COMPETE, QREN, PT2020 Partnership Agreement), ERC grant: (ERC-2011-AdG 294709-DAMAGECONTROL).info:eu-repo/semantics/publishedVersio

Liposomal drug delivery in an in vitro 3D bone marrow model for multiple myeloma

Maaike VJ Braham,1 Anil K Deshantri,2,3 Monique C Minnema,4 F Cumhur &Ouml;ner,1 Raymond M Schiffelers,2 Marcel HAM Fens,2,5 Jacqueline Alblas1 1Department of Orthopaedics, University Medical Center Utrecht, Utrecht, the Netherlands; 2Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, the Netherlands; 3Department of Pharmacology, Sun Pharma Advanced Research Company Limited, Vadodara, Gujarat, India; 4Department of Hematology, University Medical Center Utrecht Cancer Center, Utrecht, the Netherlands; 5Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands Purpose: Liposomal drug delivery can improve the therapeutic index of treatments for multiple myeloma. However, an appropriate 3D model for the in vitro evaluation of liposomal drug delivery is lacking. In this study, we applied a previously developed 3D bone marrow (BM) myeloma model to examine liposomal drug therapy. Material and methods: Liposomes of different sizes (~75&ndash;200 nm) were tested in a 3D BM myeloma model, based on multipotent mesenchymal stromal cells, endothelial progenitor cells, and myeloma cells cocultured in hydrogel. The behavior and efficacy of liposomal drug therapy was investigated, evaluating the feasibility of testing liposomal drug delivery in 3D in vitro. Intracellular uptake of untargeted and integrin &alpha;4&beta;1 (very late antigen-4) targeted liposomes was compared in myeloma and supporting cells, as well as the effectivity of free and liposome-encapsulated chemotherapy (bortezomib, doxorubicin). Either cocultured myeloma cell lines or primary CD138+ myeloma cells received the treatments. Results: Liposomes (~75&ndash;110 nm) passively diffused throughout the heterogeneously porous (~80&ndash;850 nm) 3D hydrogel model after insertion. Cellular uptake of liposomes was observed and was increased by targeting very late antigen-4. Liposomal bortezomib and doxorubicin showed increased cytotoxic effects toward myeloma cells compared with the free drugs, using either a cell line or primary myeloma cells. Cytotoxicity toward supporting BM cells was reduced using liposomes. Conclusion: The 3D model allows the study of liposome-encapsulated molecules on multiple myeloma and supporting BM cells, looking at cellular targeting, and general efficacy of the given therapy. The advantages of liposomal drug delivery were demonstrated in a primary myeloma model, enabling the study of patient-to-patient responses to potential drugs and treatment regimes. Keywords: liposomes, targeted delivery, tumor microenvironment, drug sensitivity and resistance testing, multiple myelom