Ethyl pyruvate induces necrosis-to-apoptosis switch and inhibits high mobility group box protein 1 release in A549 lung adenocarcinoma cells

Ethyl pyruvate (EP), a stable lipophilic pyruvate derivative, has been shown to exert anti-inflammatory activities through inhibiting the expression of various pro-inflammatory mediators as well as circulating levels of high mobility group box protein I (HMGB 1) in a variety of in vitro and in vivo model systems. Necrotic cell death triggers an inflammatory response through release of HMGB I in the extracellular space due to the membrane rupture. In an effort to better understand the pharmacological action mechanism that could explain the anti-inflammatory properties of EP, we examined the effects of EP on necrotic cell death in A549 lung adenocarcinoma cells in response to glucose deprivation (GD), a common characteristic of the tumor microenvironment. Here we show that EP prevented GD-induced necrosis and HMGB1 release and switched the cell death mode to apoptosis through inhibitin-GD-induced CuZn superoxide dismutase release and ROS production. These results suggest that the necrosis-to-apoptosis switch activity of EP may contribute to its anti-inflammatory action and that EP may suppress tumor development possibly through its activity to induce the cell death mode switch from tumor promoting necrotic cell death to tumor suppressive apoptotic cell death.