Efeito do selênio orgânico e da vitamina E no crescimento tumoral e na resposta imunológica ao tumor experimental de Ehrlich

Abstract

Cancer incidence has increased all over the world; in Brazil this disease has been considered a public health issue. However, tumor establishment in the organism depends on the immunologic escape mechanism in which tumors cells have strategies to inhibit the immune system recognition. This escape mechanism contributes to the tumor growth and development, so the tumor can invade the organism being able to cause serious damages or even death to the host if it is not treated in time. The number of researches has also increased intending to find out the healing or, at least a better quality of life for thoseindividuals that suffer from cancer. One of the actual researches line refers to the usage of antioxidant for treating or preventing cancer. Between the composts utilized are the selenium and vitamin E. In this work, we studied the effect of organic selenium and vitamin E in Ehrlich tumors (solid form) growth and immunologic answer to this tumor. Eightweeks old females mice BALB/c, split up into 6 groups were given the following diet: selenium supplemented diet, vitamin E supplemented diet and non supplemented diet. After two weeks treatment three groups received 2,5x106 tumor cells by footpad and other 3 groups received saline 0,9%. These animals were kept in diet for four weeks thereafter,then they were sacrificed and spleen, lymph nodes popliteal, footpad and blood were collected. Our results show that only those animals supplemented with vitamin E presented a tumor growth inhibition. These animals also had a higher CD69 expression by NK cells and CD8+ lymphocytes in the lymph nodes popliteal what reflects a higher activation of these cells. Furthermore, the animals supplemented with vitamin E without tumor inoculation showed a higher percentage of NK cells in the lymph nodes popliteal and spleen, the same result was seen in spleen from animals supplemented with selenium without tumor inoculation. The vitamin E treatment also reduced the percentage of CD4+CD25+ cells in the spleen and inhibited IL-10 production by lymph nodes popliteal cells and NO production by spleen cells. Histology showed that both treatments have the same characteristic, with the same size and mononuclear infiltrated necrosis areas. However, apoptosis rate analyses in the tumor footpad histology showed that animals treated with vitamin E presented a higher apoptosis rate when compared with other groups. The results from our study showed that vitamin E supplementation is able to inhibit Ehrilch tumors growth, activating immune system cells such as NK lymphocytes that culminate inapoptosis induction of tumors cells.