Triptolide induces apoptosis and cytoprotective autophagy by ROS accumulation via directly targeting peroxiredoxin 2 in gastric cancer cells

Abstract

Triptolide, a natural bioactive compound derived from herbal medicine Tripterygium wilfordii, has multiple biological activities including anti-cancer effect, which is being tested in clinical trials for treating cancers. However, the exact mechanism by which Triptolide exerts its cytotoxic effects, particularly its specific protein targets, remains unclear. Here, we show that Triptolide effectively induces cytotoxicity in gastric cancer cells by increasing reactive oxygen species (ROS) levels. Further investigations reveal that ROS accumulation contributes to the induction of Endoplasmic Reticulum (ER) stress, and subsequently autophagy induction in response to Triptolide. Meanwhile, this autophagy is cytoprotective. Interestingly, through activity-based protein profiling (ABPP) approach, we identify peroxiredoxins-2 (PRDX2), a component of the key enzyme systems that act in the defense against oxidative stress and protect cells against hydroperoxides, as direct binding target of Triptolide. By covalently binding to PRDX2 to inhibit its antioxidant activity, Triptolide increases ROS levels. Moreover, overexpression of PRDX2 inhibits and knockdown of the expression of PRDX2 increases Triptolide-induced apoptosis. Collectively, these results indicate PRDX2 as a direct target of Triptolides for inducing apoptosis. Our results not only provide novel insight into the underlying mechanisms of Triptolide-induced cytotoxic effects, but also indicate PRDX2 as a promising potential therapeutic target for developing anti-gastric cancer agents.

Keywords: Autophagy; Endoplasmic reticulum stress; Gastric cancer; Peroxiredoxin-2; Triptolide.