2-Chloroethyl ethyl sulfide (CEES) is a well-known chemical warfare agent that induces cellular stress in exposed individuals. However, molecular mechanisms of CEES-induced oxidative stress-mediated metabolic deregulation are not clearly elucidated. Here we investigated CEES-induced free radical production act as key functional mediators of metabolic stress via Erk1/2 mitogen-activated protein kinases (MAPKs) and phosphatidylinositol-3-kinase (PI3K/Akt) signaling cascades in keratinocytes. We observed that CEES exposure disrupts the cellular antioxidant defense capacities leading to increase in free oxygen and nitrogen radical accumulation in keratinocytes. These unusual cellular abnormalities initiate cellular stress via Erk1/2-PI3K/Akt signaling pathways. Biochemical tools were used to analyze the changes in metabolites including sulfur amino acids (SAAs), namely, L-glutathione (GSH) and L-cysteine (Cys), in the presence of selective inhibitors of reactive oxygen/nitrogen species (ROS/RNS), Erk1/2, or PI3K/Akt after CEES exposure. Importantly, these metabolite changes were accompanied by a decrease in the glycolytic flux, consistent with the observed decrease in 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) concentration and these CEES-induced phenomena were attenuated by pretreatment of Erk1/2 or PI3-K/Akt inhibitors. On the other hand, CEES exposure disrupts the protein carbonylation (PC) and lipid peroxidation (LPO) in keratinocytes leading to inflammation, crash of the cell-cell communication, cell cycle deregulation, and apoptosis via Erk1/2-PI3K/Akt pathways. However, pretreatment of Erk1/2 or PI3K/Akt inhibitors attenuated the CEES action. Collectively, these results illustrated that accumulated free radicals act as key functional mediators for inflammation, and apoptosis via Erk1/2-PI3K/Akt regulatory signaling cascades induced by CEES exposure. Treatment of pharmacological Erk1/2-PI3K/Akt inhibitors attenuated the CEES-induced keratinocyte injury that may provide the basis for the development of therapeutic strategy to work against CEES exposure.
Keywords: Apoptosis; CEES; Erk1/2-PI3K/Akt; Inflammation; Metabolites; Oxidative stress.