Metastatic Melanoma: A Preclinical Model Standardization and Development of a Chitosan-Coated Nanoemulsion Containing Temozolomide to Treat Brain Metastasis.

Melanoma is the most aggressive type of skin cancer. Brain metastasis is the worst scenario in metastatic melanoma and the treatment options for these patients are limited. Temozolomide (TMZ) is a chemotherapy agent used to treat primary central nervous system tumors. Our objective was to develop chitosan-coated nanoemulsion containing temozolomide (CNE-TMZ) for nasal route administration to melanoma brain metastasis treatment. A preclinical model of metastatic brain melanoma was standardized, and the efficiency of the developed formulation was further determined in vitro and in vivo. The nanoemulsion was done by spontaneous emulsification method and the formulation was characterized by size, pH, polydispersity index, and zeta potential. Culture assessments to determine cell viability were done in the A375 human melanoma cell line. To determine the safety of formulation, healthy C57/BL6 mice were treated with a nanoemulsion without TMZ. The model in vivo used B16-F10 cells implanted by stereotaxic surgery in C57/BL6 mice brains. The results demonstrate that the preclinical model used showed to be useful to analyze the efficiency of new candidate drugs to treat melanoma brain metastasis. The chitosan-coated nanoemulsions with TMZ showed the expected physicochemical characteristics and demonstrated safety and efficacy, reducing around 70% the tumor size compared to control mice, and presenting a tendency in mitotic index reduction, becoming an interesting approach to treat melanoma brain metastasis.

Chronic administration of methionine and/or methionine sulfoxide alters oxidative stress parameters and ALA-D activity in liver and kidney of young rats.

High levels of methionine (Met) and methionine sulfoxide (MetO) are found in several genetic abnormalities. Oxidative stress is involved in the pathophysiology of many inborn errors of metabolism. However, little is known about the role of oxidative damage in hepatic and renal changes in hypermethioninemia. We investigated the effect of chronic treatment with Met and/or MetO on oxidative stress parameters in liver and kidney, as lipid peroxidation (TBARS), total sulfhydryl content (SH), reactive oxygen species (ROS) and enzymes activities superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and delta aminolevulinic dehydratase (ALA-D). Serum biochemical parameters were evaluated. Wistar rats were treated daily with two subcutaneous injections of saline (control), Met (0.2-0.4 g/kg), MetO (0.05-0.1 g/kg) and the association between these (Met plus MetO) from the 6th to the 28th day of life. Our data demonstrated an increase of glucose and urea levels in all experimental groups. Cholesterol (MetO and Met plus MetO) were decreased and triglycerides (MetO) were increased. SOD (MetO and Met plus MetO) and CAT (Met, MetO and Met plus MetO) activities were decreased, while GPx was enhanced by MetO and Met plus MetO treatment in liver. In kidney, we observed a reduction of SH levels, SOD and CAT activities and an increase of TBARS levels in all experimental groups. ROS levels in kidney were increased in MetO and Met plus MetO groups. ALA-D activity was enhanced in liver (MetO and Met plus MetO) and kidney (Met plus MetO). These findings help to understand the pathophysiology of hepatic and renal alterations present in hypermethioninemia.