Neddylation inhibitor MLN4924 enhances H3K18 lactylation via binding to LDH and downregulates ITGB4 to block metastasis.

MLN4924, a small molecule neddylation inhibitor and a potent anticancer agent, was previously shown to have some neddylation-independent effects. Whether MLN4924 regulates histone lactylation in neddylation-dependent or independent manner is previously unknown. We reported here that MLN4924 significantly increased the lactate levels by activating lactate dehydrogenase (LDH) activity via inducing LDH tetramerization to promote histone H3K18 lactylation in breast cancer cells. Through combined analyses of cleavage under target & tagmentation, RNA-seq, and CHIP-PCR, we identified integrin ITGB4 as a downstream target, subjected to downregulation by MLN4924-induced H3K18 lactylation, occurred at the first intron of the ITGB4 gene. This MLN4924-mediated dose- and time-dependent ITGB4 downregulation is independent of its neddylation inhibition but can be largely abrogated by siRNA-based LDH knockdown or treatment with oxamate, a small molecular inhibitor of LDH. Biologically, MLN4924 effectively suppresses the migration and invasion of breast cancer cells in vitro and metastasis in vivo, which is largely rescued by ITGB4 overexpression. Taken together, our study revealed a new mechanism by which MLN4924 suppresses the migration and invasion of breast cancer cells by epigenetically inhibiting ITGB4 expression via enhancing H3K18 lactylation.