Adipocytes-derived β-hydroxybutyrate confers the resistance of myeloma cells to metabolic stress

Albeit being recognized as one of the major mesenchymal cells and a dangerous accomplice in myeloma, the roles of adipocytes in different stages of myeloma pathogenesis remain elusive. Here we showed that glucose metabolic stress impairs protein stability of interferon regulatory factor 4 (IRF4), an oncoprotein essential for myeloma cell survival, while adipocytes-derived β-hydroxybutyrate (β-OHB) preserves IRF4 stability and cell survival. Mechanistically, glucose deficiency activates the AMP-activated protein kinase (AMPK) to disrupt the interaction of IRF4 with heat shock protein 90 (HSP90), enabling the E3 ligase TRIM21-mediated IRF4 ubiquitination degradation. The presence of β-OHB drives 3-oxoacid CoA-transferase 1 (OXCT1)-mediated ketolysis and facilitates N-acetyltransferase 10 (NAT10)-mediated IRF4 acetylation at lysine 87, which restores IRF4’s interaction with HSP90 and precludes TRIM21-mediated IRF4 degradation. Notably, targeting OXCT1 or NAT10 to interfere with β-OHB utilization displays a synergistic anti-myeloma effect in combination with AMPK activator both in vitro and in vivo. Our study thus positions adipocytes-derived β-OHB as a pivotal contributor that enables myeloma cells to overcome glucose metabolic stress and suggests viable therapeutic targets to be exploited for multiple myeloma treatment.