NSD2 promotes HCC metastasis through methylating PKM2 and activating SF3B1-dependent alternative splicing

Hepatocellular carcinoma (HCC) is notorious for its early and frequent metastases. To understand the molecular mechanisms underlying HCC metastasis, we generated a pulmonary metastasis HCC mouse model and performed both time-series transcriptomics and proteomics analysis of protein methylation. We found that methyltransferase NSD2 with significant upregulation in the tipping point for metastasis was closely correlated with high numbers of methylated-proteins in HCC tissues. NSD2 promoted the invasion and metastasis of HCC cells, both in vitro and in vivo. Mechanistically, NSD2 directly bound to PKM2, a glycolysis rate-limiting enzyme, and catalyzed di-methylation of PKM2 at the lysine 336 residue. Further investigation demonstrated that NSD2-mediated di-methylation of PKM2 increased the intracellular glycolytic rate and lactate production by enhancing its pyruvate kinase activity. High-lactate level in HCC cells lead to lactylation of splicing factor 3B subunit 1 (SF3B1) at lysine 333 residue, promoting SF3B1-mediated RNA splicing of several metastasis-related genes. Further, UNC8153, a novel NSD2-targeted degrader, inhibited HCC metastasis in PDX model. Altogether, our study identifies a key methyltransferase NSD2 for HCC metastasis and reveals a protein methylation-mediated molecular mechanism catalyzed by NSD2 integrate glycolysis regulation and alternative splicing.