Ação da melatonina no microambiente tumoral anaeróbico verificada por marcadores de hipóxia e metabolismo energético em modelo experimental de câncer de mama

Abstract

Breast cancer is the most common cancer among women and has a high mortality rate. The rapid tumor growth hinders the infusion of O2, mainly in the central region of the tumor, thus, adverse conditions in the tumor microenvironment, such as hypoxia and acidosis, may exert selective pressure on the tumor, selecting subpopulations of tumor cells with advantages for survival in this environment. In this context, therapeutic agents that can be used to control these conditions, and consequently the intratumoral heterogeneity need to be explored. Melatonin, in addition to its physiological effects has demonstrated important anti-tumor actions and recently has been associated with the control of hypoxia and Warburg effect. Objetives - In this study, we evaluated the action of melatonin on cell viability, tumor growth and tumor metabolism evaluated by different markers of hypoxia and energy metabolism (HIF-1α, glucose transporters GLUT1 and GLUT3 and carbonic anhydrases CA-IX and CA-XII) in triple negative breast cancer in vitro and in vivo model. Methods - In vitro cell viability was investigated by the MTT (methyl-thiazole-tetrazolium) assay and gene and protein expressions by quantitative real-time PCR and immunocytochemistry, respectively. Melatonin effects were tested in vivo, using athymic nude mice injected with MDA-MB-231 cells (xenograft model). Tumor growth and necrosis were evaluated by images obtained by positron emission tomography (PET / CT). Results - Results showed that melatonin treatment reduced the viability of MDA-MB-231 cells and controls tumor growth and necrosis in Balb/c nude mice (p <0.05). The treatment also decreased HIF-1α gene and protein expression, concomitantly with the expression of energy metabolism markers (p <0.05). Conclusion - Taken together, these results show that melatonin down-regulates HIF-1α expression and consequently, it can regulates energy metabolism markers (GLUT-1, GLUT-3, CA-IX and CA-XII) in breast tumor cells, controlling hypoxia and tumor progression.