Citotoxicidade de Células Natural Killer do Colostro Humano Moduladas pela Melatonina sobre Linhagens de Células de Tumor de Mama (MCF-7)

Abstract

Cancer is one of the most related causes of mortality and morbidity in children and adults, has become one of the main health problems in the world. Human colostrum has several bioactive components such as enzymes, antioxidant factors, cytokines, hormones, and cells with action on infectious diseases and antitumor activity. 3 to 5% of the cellular components are represented by natural killer (NK) cells, but their actions on breast tumor cell lines are still partially understood. Studies have suggested that melatonin has antioxidant functions and may act as a potent immunomodulator on cell activity. Still, no studies have reported the effects of this hormone on colostrum NK cell cytotoxicity when in the presence of breast tumor cell lines. Thus, this study aimed to evaluate the effects of the hormone melatonin on the natural cytotoxicity activity to colostrum NK tumors for human breast adenocarcinoma cell lines (MCF-7). The NK cells were obtained from 15 colostrum samples were collected from clinically healthy women in the municipality of Barra do Garças (MT) to obtain these cells, which were evaluated in the presence of the hormone melatonin (100 ng/mL) in coculture with cells of breast adenocarcinoma (MCF-7) for 24 hours, 37 °C at 5% CO² and also CR3 receptor expression by immunophenotyping assay. It was observed that colostrum NK cells are cytotoxic to MCF-7 cells and that melatonin can increase NK cytotoxicity and CR3 receptor expression. These data suggest that the interactions of colostrum NK cells with the hormone melatonin are essential for tumor immunity, as melatonin potentiates the cytotoxic NK response and may act as a protective mechanism against breast cancer conferred to mothers through breastfeeding.