Cell internalization of 7-ketocholesterol-containing nanoemulsion through LDL receptor reduces melanoma growth in vitro and in vivo: a preliminary report

Abstract

Oxysterols are cholesterol oxygenated derivatives which possess several biological actions. Among oxysterols, 7-ketocholesterol (7KC) is known to induce cell death. Here, we hypothesized that 7KC cytotoxicity could be applied in cancer therapeutics. 7KC was incorporated into a lipid core nanoemulsion. As a cellular model the murine melanoma cell line B16F10 was used. The nanoparticle (7KCLDE) uptake into tumor cells was displaced by increasing amounts of low-density-lipoproteins (LDL) suggesting a LDL-receptor-mediated cell internalization. 7KCLDE was mainly cytostatic, which led to an accumulation of polyploid cells. Nevertheless, a single dose of 7KCLDE killed roughly 10% of melanoma cells. In addition, it was observed dissipation of the transmembrane potential, evidenced with flow cytometry; presence of autophagic vacuoles, visualized and quantified with flow cytometry and acridine orange; and presence of myelin figures, observed with ultrastructural microscopy. 7KCLDE impaired cytokenesis was accompanied by changes in cellular morphology into a fibroblastoid shape which is supported by cytoskeletal rearrangements, as shown by the increased actin polymerization. 7KCLDE was injected into B16 melanoma tumor-bearing mice. 7KCLDE accumulated in the liver and tumor. In melanoma tumor 7KCLDE promoted a >50% size reduction, enlarged the necrotic area, and reduced intratumoral vasculature. 7KCLDE increased the survival rates of animals, without hematologic or liver toxicity. Although more pre-clinical studies should be performed, our preliminary results suggested that 7KCLDE is a promising novel preparation for cancer chemotherapy.

Current Applications of Nanoemulsions in Cancer Therapeutics

“…Paclitaxel (PTX) is an anticancer drug often used to treat lung, breast, pancreatic, and ovarian cancer. It has the ability to interfere with the breakdown of microtubules during cellular division, leading to apoptosis, mitotic arrest, and inhibition of cell functions [108]. PTX has very low water solubility, which is why many formulations, like Taxol ® containing Cremophor-EL ® and ethanol, have been developed.…”

7-Ketocholesterol and cholestane-triol increase expression of SMO and LXRα signaling pathways in a human breast cancer cell line

“…These properties led us to investigate the potential use of oxysterols as chemotherapeutic agents in cancer [23]. Our results showed that 7-ketocholesterol (7-KC), a well-known oxysterol, had cytostatic and cytotoxic effects on melanoma, in vitro and in vivo.…”

Características da toxicidade promovida por oxisteróis em células-tronco mesenquimais derivadas da medula óssea de pacientes com leucemia mieloide aguda

“…Outra via de morte celular que pode ser presenciada nas células tratadas com oxisteróis é a necrose, que foi observada tanto em experimentos in vitro como in vivo (Favero et al, 2018;Silva et al, 2016). A necrose, pode ser identificada através do inchaço celular que leva ao rompimento da membrana plasmática e consequentemente ao extravasamento do conteúdo celular (Yamanaka et al, 2011).…”

“…Porém, em outro estudo, foi possível observar que os oxisteróis citotóxicos foram capazes de inibir a fase S do ciclo celular e estimular a fase G0/G1 ou a fase G2/M em linhagem de câncer de mama (Levy et al, 2018). Em outro trabalho foi observado uma redução do tamanho da área tumoral em mais de 50 %, em modelo de melanoma murino (Favero et al, 2018). O presente trabalho visa estudar as características da morte de células-tronco mesenquimais de medula óssea de pacientes com leucemia mieloide aguda promovida por oxisteróis.…”

“…Através de vários mecanismos, os oxisteróis tem a capacidade de induzir morte celular nas mais variadas linhagens celulares. Entre os oxisteróis biologicamente ativos, além de características citotóxicas, também é observado características oxidativas (Favero et al, 2018). Dos diversos oxisteróis, o 7-KC é conhecido pela propriedade de indução da morte celular e estresse oxidativo.…”