Discovery of spirocyclic amide scaffolds as novel neddylation E1 inhibitors to suppress the growth and survival of lung cancer cells.

This study identifies and characterizes compound 24 (HA-218-6-31-80), a novel small-molecule NEDD8-activating enzyme (NAE) inhibitor. Discovered from a high-throughput screening, followed by structure-guided optimization, compound 24 possesses a distinct spirocyclic amide chemical core entirely different from the clinical-stage NAE inhibitor MLN4924. Biochemical assays confirm that compound 24 directly binds NAE and suppresses its catalytic activity, blocks the formation of E2-NEDD8 thioesters, and reduces the neddylation of CUL1 and CUL5 in purified protein systems. In human lung cancer cells, it potently suppresses neddylation of multiple CUL family members, leading to the accumulation of CRL substrates including p27 and NOXA. Functionally, it triggers G1-phase arrest and NOXA-dependent apoptosis, inhibiting lung cancer cell proliferation and survival. In A549 xenograft models, it significantly suppresses tumor growth without obvious systemic toxicity. Collectively, 24 (HA-218-6-31-80) represents a promising NAE inhibitor, offering a potential therapeutic candidate for lung cancer and a novel scaffold for neddylation targeted drug discovery.