Reactive oxygen species: the achilles' heel of cancer cells?

Cancer development, progression, and metastasis are multistep processes. Accumulating evidence suggests that reactive oxygen species (ROS) are critically involved in cancer cell functions. This Forum reviews our current understanding of the important and paradoxical role of ROS in the regulation of tumor-associated cell properties, genes, and signaling pathways. The six reviews in this Forum showcase the up-to-date knowledge on how ROS modulate or interact with the p53 protein, epithelial-mesenchymal transition, tumor stromal cells, angiogenesis, and cancer stem cells, which are essential factors in cancer development and metastasis. The contributions demonstrate that ROS levels in cancer cells are tightly controlled, which brings promises and challenges in the development of novel ROS-targeted anticancer therapies. Further understanding of the biological mechanisms underlying the effects of oxidative stress on tumor growth and metastasis will contribute to the advancement of cancer biology and cancer treatment.