The role of oxidative stress on breast cancer development and therapy.

Reactive oxygen species (ROS) are produced by both enzymatic and non-enzymatic systems within eukaryotic cells and play important roles in cellular physiology and pathophysiology. Although physiological concentrations are crucial for ensuring cell survival, ROS overproduction is detrimental to cells, and considered key-factors for the development of several diseases, such as neurodegenerative diseases, cardiovascular disorders, and cancer. Cancer cells are usually submitted to higher ROS levels that further stimulate malignant phenotype through stimulus to sustained proliferation, death evasion, angiogenesis, invasiveness, and metastasis. The role of ROS on breast cancer etiology and progression is being progressively elucidated. However, less attention has been given to the development of redox system-targeted strategies for breast cancer therapy. In this review, we address the basic mechanisms of ROS production and scavenging in breast tumor cells, and the emerging possibilities of breast cancer therapies targeting ROS homeostasis.