HS probe CPC inhibits autophagy and promotes apoptosis by inhibiting glutathionylation of Keap1 at Cys434.

HS is actual an endogenous signaling gas molecule and involved in a range of cell physiological processes. However, the mechanism of endogenous HS regulating autophagy and apoptosis has not been thoroughly investigated. Here, we try to address this issue by using a HS probe, (E)-2-(4-(4-(7-(diethylamino)-2-oxo-2H-chromene-3-carbonyl)-piperazin-1-yl)-styryl)-1, 3, 3-trimethyl-3H-indol-1-ium iodide (CPC), which could react with endogenous HS. Herein, we reported that CPC inhibited autophagy and decreased the expression and activity of NF-E2-related factor 2 (Nrf2), then induced cell apoptosis. CPC inhibited autophagy and promoted apoptosis by inhibiting Nrf2 activation, which was HS dependent. Furthermore, we found that CPC inhibited Nrf2 nucleus translocation by inhibiting glutathionylation of Kelch-like ECH-associated protein 1 (Keap1) at the Cys434 residue. CPC also inhibited various cancer cell growth, but had no effect on normal cell growth in vitro, and inhibited A549 cancer growth, but did not affect normal angiogenesis in vivo. Therefore, we not only found a new inhibitor of autophagy and Nrf2, but also suggested a novel mechanism that endogenous HS could regulate autophagy, apoptosis and Nrf2 activity through regulating glutathionylation of Keap1 at the Cys434 residue.