Tumor development under the perspective of redox signaling: temporal modulation of the production of nitric oxide and reactive oxygen species

Abstract

Cancer development is closely related to a condition of chronic inflammation. To this condition, markers of tumor progression such as uncontrolled cell proliferation, angiogenesis, genomic instability, chemoresistance, and metastasis are frequently associated. Within the inflammatory tumor microenvironment, redox processes mediated by Reactive Oxygen Species (ROS) and Nitric Oxide (NO) play an essential role in intercellular and intracellular communication, directly influencing in signaling events. In addition, these reactive species originated from the tumor cell or from its microenvironment, potentially could mediate the Epithelial-Mesenchymal Transition (EMT) and the Mesenchymal-Epithelial Transition (MET). However, intracellular interactions between NO and ROS have to be avoided to prevent cell death. Therefore, this research proposal aims to explore the mechanisms developed by tumor cells to survive and adapt to highly stressed conditions. We hypothesized that a space-temporal fine adjustment of intracellular concentrations of NO and ROS would operate to guarantee the successful development of tumor cells. Within this context our research efforts will focus on the understanding of the temporal aspects of the generation of NO and ROS within the three stages of tumor development: (a) in the growing process of the tumor at the primary site; (b) at the edge of the growing tumoral mass at the primary site where cells undergoing EMT will migrate to the metastatic site; and (c) in the establishment of the migrating tumor cell in the metastatic site upon occurrence of MET. To this end, human breast, colon, and melanoma cell lines will be used. Our specific aims within this research proposal will include: (1) to determine and relate the intracellular levels of NO and ROS to tumor development; (2) to determine the role of NO and ROS as mediators of oncogenic signaling pathways and their relationship with the stages of tumor development; (3) to investigate the connections between the endogenous production of NO and ROS, the EMT and MET transitions, and anoikis resistance; (4) to perform the clinical translation of the findings obtained during the development of Specific Aims 1, 2, and 3 using samples from breast, colon, and melanoma patients; (5) to develop new experimental strategies to modulate the levels of NO and ROS in tumor cell lines aiming to develop new prototypes of chemotherapeutic agents. The experimental design of this research proposal will involve the production of genetically modified tumor cell lines with different capacities to produce NO and ROS. We will use molecular and cell biology - based techniques to characterize the redox signaling pathways and their connections with the EMT and MET transitions in these cells. Wild type and genetically modified tumor cell lines will be implanted in immunodeficient mice to evaluate in vivo the signaling pathways characterized in in vitro experiments. Following, we will perform the clinical translation of the experimental findings obtained within in vitro and in vivo experiments. Understanding tumor development under the perspective of redox signaling will allow for the characterization of new markers of tumor development. In addition the synthesis of compounds with the capacity to modify the intracellular levels of NO and ROS potentially will target the redox homeostasis operative in tumor cells. By acting in this way these compounds are potential and promising chemotherapeutic agents that can effectively target tumor cells at specific stages of development. (AU)