Melatonina como imunomodulador de células natural killer do colostro humano sobre células do carcinoma de mama humano

Abstract

Human colostrum has several bioactive components such as enzymes, antioxidant factors, cytokines, hormones, and immune system cells that are transferred through breastfeeding and which reduce the likelihood of developing breast cancer in mothers. Among the cellular components of colostrum, only approximately 3 to 5% are represented by natural killer (NK) cells, but their actions on breast tumor cell lines are still partially understood. Studies have suggested that the hormone melatonin present in colostrum can act as a potent immunomodulator on cellular activity. Still, no study has reported the effects of this hormone on these cells in the presence of breast tumor cell lines. Thus, this study aimed to evaluate melatonin's effects on the natural tumor cytotoxicity of colostrum NK cells for human breast adenocarcinoma cell lines (MCF-7). Colostrum samples were collected from 25 clinically healthy women in Barra do Garças (MT) to evaluate the cytotoxicity of natural killer cells, which were evaluated in the presence of the hormone melatonin (100 ng/mL) in coculture with mammary adenocarcinoma cells (MCF-7) for 24 hours, at 37 °C at 5% CO² and the phenotype of NK cells and the expression of the CR3 receptor were also evaluated by immunophenotyping assay. Coculture of colostrum cells with MCF-7 cell lines, independent of melatonin treatment, increased the expression of CD16⁺ cells, CD56⁺ cells, and CD16⁺/CD56⁺ cells. Colostrum NK cells were observed to present cytotoxicity to MCF-7 cells, and melatonin can increase NK cytotoxicity and expression of the CR3 receptor. According to the data, the interaction between colostrum NK cells and the hormone melatonin plays a crucial role in tumor immunity. The study suggests that melatonin enhances the cytotoxic response of NK cells and acts as a protective mechanism against breast cancer. This protective effect is passed on to infants through breastfeeding.