Necroptosis is a classical mode of cell death co-regulated by RIPK1, RIPK3, and mixed lineage kinase domain-like pseudokinase (MLKL). Necroptosis begins with the activation of death receptors, such as tumor necroptosis factor (TNF) receptor 1. RIPK1, a key upstream protein of the necroptosis pathway, then intercalates with RIPK3. RIPK1/RIPK3 forms necrosomes and leads to RIPK3 phosphorylation (p-RIPK3). p-RIPK3 recruits oligomerized MLKL to the plasma membrane, triggering membrane perforation and rupture. As a result, cellular contents and damage-associated molecular patterns (DAMPs) are released, triggering inflammation and cell death. Blocking necroptosis pathways is critical to inhibiting inflammatory pathways. So here we introduce a potent RIPK1 kinase inhibitor, KWCN-41.

KWCN-41 is a selective PIPK1 inhibitor over PIPK3 and inhibits necroptosis (EC₅₀=56 nM).

KWCN-41 exhibits a potent anti-inflammatory effect vai targeting RIPK1 (IC₅₀=88 nM). During an in vitro study, KWCN-41 dose-dependent inhibits necroptosis in L929 cells (EC₅₀=56 nM). However, it also specifically inhibits necroptosis rather than apoptosis. KWCN-41 suppresses TZ or TSZ-induced necroptosis in L929 cells (39 nM-1 μM; 6 h) but helps little for TS (TNF-α, Smac mimetic) induced apoptosis in HT-29 cells (39 nM-10 μM; 12 h). Currently at WB assay, KWCN-41 (250 μM; 2.5 h) significantly inhibits RIPK1, RIPK3, and MLKL phosphorylation in L929 cells.

As for in vivo study, use systemic inflammatory response syndrome (SIRS) model induced by TNF-α and characterized by cold injury. KWCN-41 (25 mg/kg, 40 mg/kg; i.p.; single dose) significantly reduces hypothermic injury in mice SIRS model. It also decreases the level of inflammatory factor IL-6 to inhibit SIRS development.

Above, KWCN-41 is a potent inhibitor of RIPK1, as well as necroptosis. It protects cells from inflammation via inhibiting RIPK1, RIPK3, and MLKL phosphorylation.

Reference:

[1] Cui N, et al. Eur J Med Chem. 2023 Mar 15;250:115190.