Abstract 5130: Melanoma and breast adenocarcinoma growth inhibition by a 7-ketocholesterol loaded-phosphatidylserine liposome
Authors: Giovani M. Favero, Tharcisio C. Tortelli, Andreia H. Otake, Luciana N. Andrade, Daniele P. Faria, Camila G. Carneiro, Alexandre T. Garcez, Fabio L. Marques, Roger Chammas
Journal: Cancer Research (2018)

Abstract Background: Phosphatidylserine (PS) exposure is one of the first steps of programmed cell death. Phagocytosis on cancer microenvironment is described in tumors and is associated with malignancy and poor prognosis. Tumor Associated Macrophages (TAMs) act suppressing the anticancer immune response. Recently we observed that 7-Ketocholesterol (7KC) induces autophagy on melanoma cell. Aims: Evaluate a 7-ketocholesterol loaded-phosphatidylserine liposome on autophagy and phagocytosis of tumor microenvironment. Methods: Liposomes were constituted by 20 mg PS or PS associated with 5 mg of 7KC extracted, dried, resuspended in phosphate buffer and sonicated. The size and Zeta Pontencial (ZP) were evaluated. A dependent-dose effect of liposomes on J774 macrophages, B16F10 melanoma cells and 4T1 breast cancer cells were assessed by MTT. Cell death evaluations, for the same cells, were performed by flow cytometry. The presence of acid vacuoles related to autophagy was evaluated by acridine orange staining. The effects of the liposomes in vivo were evaluated by B16F10 melanoma bearing C57/bl6 mice and 4T1 breast cancer bearing mice. Endocytosis efficiency of the liposomes was PKH26 fluorescent staining. Liposomes were radiolabeled by adding 1 to 30 mCi of 99mTc radiopharmaceuticals (99mTcO4-, 99mTc-dextran-70, 99mTc-MIBI, 99mTc-DISIDA) and 18FDG. Results: PS liposomes presented 141,9nm + 9,101 size with a -25,2 ZP; PS-7-Ketocholesterol (PS/7KC) liposomes presented 153,9 nm + 10,35 size with a -29,1 ZP.PS/7KC showed intense antiproliferative activity in melanoma cells and breast adenocarcinoma cells. There was 10% more autophagic vacuoles on melanoma cells treated with PS/7KC than the control groups. Both in vivo tumor models had the same antiproliferative effect of the PS/7KC liposomes with daily doses. Daily doses of PS liposomes induced a high size of tumors. 99mTc-MIBI was efficiently and strongly incorporated to liposomes then the other proposed formulations. Conclusion: PS liposomes have effects in vivo and in vitro related to phagocyte and autophagy activities. PS/7KC impairs J774 macrophage, B16F10 melanoma and 4T1 breast adenocarcinoma cells growth. PS/7KC induce the presence of acid vacuoles corresponding to autophagy. The liposomes had a high endocytosis evaluated by PKH 26 labelled particles. PS keep the tumor proliferation and PS/7KC inhibit tumor growth after ten days of daily doses. Supported by CNPq and Fundação Araucária Citation Format: Giovani M. Favero, Tharcisio C. Tortelli, Andreia H. Otake, Luciana N. Andrade, Daniele P. Faria, Camila G. Carneiro, Alexandre T. Garcez, Fabio L. Marques, Roger Chammas. Melanoma and breast adenocarcinoma growth inhibition by a 7-ketocholesterol loaded-phosphatidylserine liposome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5130.