Discovery of Hits That Can Specifically Inhibit Necroptosis but Not Apoptosis

Abstract

Necroptosis or programmed necrosis is a specialized and regulated necrosis, and is unmasked when apoptotic machinery for death stress is defective. Initially, it was proposed that necroptotic cell death was pathologically associated with ischemic brain injury and retinal disorders. In contrast, it plays a beneficial significance in innate immune response to viral infection that can evade host’s apoptotic surveillance. Also, it has been therapeutically emerging as the strategy to overcome the cancers with acquired anticancer drug resistance. Presently, a few small molecules to interfere with signaling pathways for necroptosis have been disclosed since necrostatin-1 (Nec-1) was for the first time identified as an inhibitor of receptor interacting protein 1 (RIP1), a key necroptosis regulator. In an effort to discover hits that can selectively inhibit necroptotic cell death, in this study, we screened in-house and in silico chemical libraries in a cell-based format. Eventually, 7 hits were identified from in-house chemical library while 2 hits were from computer modeling. Most hits less protected cells from tumor necrosis factor alpha (TNF?)- and zVAD-mediated necroptosis than a reference compound necrostatin-1, without affecting apoptotic cell death induced in HeLa. Interestingly, a few of hits had preferential protective effects on zVAD or TNF? while Nec-1 exhibited EC₅₀ values at the similar concentrations against both necroptosis inducers, suggesting that chemicals deduced in our study can discriminate signaling pathways leading to receptor or nonreceptor-mediated necroptotic cell death.Therefore, some potent hits will be further improved to use for the treatment of necroptosis-associated disorders.