A systems pharmacology approach to discovery of drugs to ameliorate oxidant stress in human endothelial cells
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Ischemia is characterized by reduced blood flow to an area of the body which can then cause cellular injury through the generation of reactive oxygen species (ROS), activation of inflammation, and induction of apoptosis. Although rapid reestablishment of flow is required to prevent organ death, the reperfusion phase of this injury can cause its own deleterious effects often exacerbating the initial insult. The combined action of the two injuries is termed ischemia/reperfusion (I/R) injury. Oxidative stress that results from ischemia/reperfusion injury is a common pathological condition that accompanies many human diseases including stroke, heart attack and traumatic injury. In addition, neurodegenerative diseases including Parkinson’s, Alzheimer’s, and Huntington’s disease appear to involve oxidative stress. Although actively investigated by the medical and pharmaceutical industry; limited progress has been made to ameliorate I/R injury and to date there is no drug approved for treatment for I/R injury. Therapeutic approaches to treat I/R injury have included the administration of compounds to scavenge ROS or induce protective pathways or genetic responses. It was previously reported that caffeic acid phenethyl ester (CAPE), a plant-derived polyphenol, displayed cytoprotective effects against menadione (MD)-induced oxidative stress in human umbilical vein endothelial cells (HUVEC), and the induction of heme oxygenase-1 (HMOX1), a phase II enzyme, played an important role for CAPE cytoprotection. In an effort to improve this cytoprotection, other phase II enzyme inducers were investigated and, 2-cyano-3,12 dioxooleana-1,9 dien-28-imidazolide (CDDO-Im) and 2-cyano-3,12-dioxooleana-1,9-dien-28-oyl methyl ester (CDDO-Me), were found to be potent inducers with a rapid onset of action. CDDO-Im and CDDO-Me, synthetic olenane triterpenoids, developed as anticancer agents were compared to CAPE revealing that CDDO-Im was a more potent inducer of Phase II enzymes including HMOX1 and provided better cytoprotection than CAPE. Gene expression profiling showed that CDDO-Im was more potent inducer of protective genes like HMOX1 than CAPE and additionally induced heat shock proteins. To better understand the mechanism of action of CDDO-IM, a gene expression time-course was undertaken to identify early initiators of the transcriptional response preceding cytoprotection. Application of systems pharmacology identified molecular networks of cell mediating processes.