Evaluación del Efecto In Vitro e In Vivo de la Combinación de Albendazol y Melatonina Sobre Glioblastoma Multiforme

Abstract

Glioblastoma (GB) is the most aggressive and lethal brain tumor in adults, which presents diffuse cerebral infiltration, drug resistance and high recurrence. The current treatment consists of surgical resection and radiotherapy with chemotherapy, with temozolomide being the drug of first choice; however, survival is approximately 15 months. Although new treatments (Bevacizumab) have been approved for patients with recurrent GB, the average survival rate is two years, therefore, it is necessary to continue exploring therapeutic alternatives that offer better results. Previous evaluations have shown the anticancer activity of albendazole (ALB), its active metabolite, albendazole sulfoxide (ALBSO) and melatonin (MLT), therefore, the objective of this work was to evaluate the in vitro effect of the combination of MLT with ALB, as well as of MLT with SOALB, considering that this metabolite has shown the highest levels in plasma and cerebrospinal fluid when administering ALB orally, in addition to conduct a pilot study to evaluate the in vivo effect of the combination ALB with MLT. For the in vitro study, C6 and RG2 rat glioma cells and U87 human glioma cells were used. The concentration-response was determined in the range of 0.16 to 1.25 μM for ALB, 2 to 64 μM for ALBSO, and 0.18 to 6 mM for MLT. Based on the mean Dose (Dm) values obtained, the concentrations for the combinations were selected. Cytotoxicity was evaluated by means of the MTT assay and drug interaction was determined by the Chou et al. method. Cell death mechanisms: apoptosis and necrosis, were evaluated using annexin V and 7-amino actinomycin D. The pilot study was carried out in Fischer rats implanted intracranially with RG2 cells, which were divided into the following groups: control, ALB, MLT, and the combination of ALB with MLT and survival was evaluated. The in vitro results showed that in all cell lines, the drugs exhibited cytotoxic activity in a concentration-dependent manner. For ALB, the Dm values in lines C6, RG2 and U87 were 0.6 μM, 0.6 μM and 0.9 μM; for ALBSO, 20 μM, 26 μM and 36 μM; and for MLT, 1 mM, 0.9 mM, and 0.9 mM, respectively. Most combinations produced a synergistic cytotoxic effect, and the cell death was induced by apoptosis. In the in vivo pilot study, a trend in the increase in survival rate after administration of the combination was found. The results indicate that the combinations could be a potential strategy for the treatment of GB, considering that these compounds are less toxic and expensive. It is necessary to continue with the molecular evaluations related to the action mechanisms involved and to perform the final in vivo study.

El glioblastoma (GB), tratado con cirugía, radioterapia y quimioterapia, presenta una supervivencia aproximada de 15 meses, por lo que se requieren nuevas alternativas terapéuticas. Evaluaciones previas demostraron actividad anticancerígena del albendazol (ALB), sulfóxido de albendazol (SOALB) y melatonina (MLT). Nuestro objetivo fue evaluar el efecto in vitro de la combinación MLT con ALB o con SOALB, e in vivo el efecto de ALB con MLT. Se utilizaron células C6, RG2 y U87. Se determinaron las dosis del efecto medio, a partir de las cuales, se diseñaron las combinaciones. La interacción farmacológica se determinó con el método de Chou y colaboradores y los mecanismos de muerte por citometría. El estudio in vivo se realizó en ratas Fischer implantadas con células RG2, y se evaluó sobrevida. Los resultados mostraron que, en todas las líneas celulares, los fármacos exhibieron actividad citotóxica de manera dependiente de la concentración. La mayoría de las combinaciones produjeron efectos sinérgicos e indujeron apoptosis. En el estudio piloto in vivo se encontró una tendencia en el incremento de la sobrevida después de la administración de la combinación. Los resultados indican que las combinaciones podrían ser una estrategia potencial para GB, considerando que estos compuestos son menos tóxicos y costosos.