Comparative cytotoxic activity of lutein or cisplatin doped with liposomes against breast cancer cell lines after radiotherapy

Abstract

Interactions of the anticancer drug cisplatin or the antioxidant drug lutein with liposomes as model membranes were characterized. All liposomes had the almost spherical shape, taking into account that lyposomes without the said drugs were more evenly dispersed and tended to aggregate less. The mean size diameter of empty liposomal samples was 617.90 ± 75.64 nm, while liposomes loaded with cisplatin, lutein and a cisplatin+lutein combination were 425.60 ± 64.74 nm, 877.85 ± 93.90 nm and 189.91 ± 136.84 nm, respectively, in diameter. The incorporation of cisplatin or lutein into liposome membranes resulted in an increase in the zeta potential values. The lowest zeta potential value was achieved in lyposomes containing cisplatin in combination with lutein. The addition of cisplatin to liposomes caused a shift in the melting temperature towards higher values than those of the main peak of empty liposomes indicating a conformational disorder within the phospholipids. Encapsulation of lutein into liposomes resulted in the disappearance of the main characteristic endothermic peak of pure liposomes. FTIR spectroscopy confirmed the interaction of lutein or cisplatin with functional groups in liposomes. In the absence of external gamma-irradiation, the IC50 value for free lutein in the cytotoxic assay with MCF-7 treated cells was 10.62 gg/ml, while free cisplatin showed the IC50 value of 41.02 gg/ml. IC50 was 65.84 gg/ml and 34.29 gg/ml for nanoliposomal lutein and cisplatin, respectively. Using the combined therapy of gamma irradiation at dose rate 5 Gray followed by 10 Gray, the IC50 value for free lutein changed from 17.0 to 9.5 gg/ml. IC50 for free cisplatin changed from 51.00 to 43.09 gg/ml. This study showed that cytotoxic effect of a standard form of lutein is stronger than that of nanoliposomal lutein. The current evidence reveals a new regimen for the treatment during which replacing cisplatin with free lutein increases anticancer activity against the MCF-7 cancer cell line.