Desenvolvimento e avaliação biológica in vitro de sistemas nanoestruturados contendo um novo organoseleneto: utilização de diferentes abordagens tecnológicas visando a sensibilização de células tumorais resistentes

Abstract

Cancer is one of the major causes of mortality worldwide and has become a public health problem. Most of the conventional cancer treatments are nonspecific and do not target the tumor cells only, also affecting healthy cells and leading to systemic toxicity associated with serious side effects. Few studies have shown that the development of nucleoside analogues modified with organochalcogens present a promising antitumor activity. Additionally, the encapsulation of antitumor drugs in nanoparticles is a promising approach that may enhance the efficacy of the currently chemotherapy drugs. These systems are able to improve the therapeutic index of various drugs, improving efficacy, reducing toxicity and achieving therapeutic index for an extended period. Moreover, some approaches as the use of pH-sensitive adjuvants or active targeting can be used to increase the antitumor efficacy of nanocarriers. In this sense, we prepared polymeric nanoparticles (NPs) using the polymer poly-lactic-co-glycolic acid as a carrier for the 5’-Se-(phenyl)-3-(amino)-thymidine (ACAT-Se), an organoselenium compound, nucleoside analogue, synthesized from zidovudine (3-azidothymidine). Firstly, the NPs were modified with a pH-sensitive adjuvant (lysine-based surfactant with litium counterion, 77KL) (NP 1) and, then, conjugated to the biomarker transferrin (Tf) (NP 2). The NPs were characterized and presented adequate physicochemical characteristics. Furthermore, DPPH (1-1-diphenyl-2- picrylhydrazyl) and ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) assays suggest that the nanoencapsulation of ACAT-Se increased the compound antioxidant activity. Hemolysis assay indicate that both NPs present hemocompatibility, and 77KL provide a pH-sensitive behavior to NP 1. The in vitro antitumor assays demonstrated that ACAT-Se-loaded to NPs induced higher cytotoxicity than free compound in sensitive and resistant tumor cells, especially for the NPs conjugated with Tf. Additionally, the antitumor activity of NP 1 combined with doxorubicin was study and presented synergistic interaction in sensitive and resistant tumor cells. The antitumor activity of the NPs was also assessed using a 3D model of tumor spheroids and, as in 2D model, the NP 2 was the most cytotoxic treatment. The Tf-decorated NPs were also able to inhibit the tumor cell migration, presented a higher cell internalization and induced a greater number of apoptotic events. Therefore, the results indicate that the NP 1, associated with doxorubicin, and the NP 2, are promising approaches to enhance efficacy of antineoplastic therapy.