LACTB suppresses liver cancer progression through regulation of ferroptosis

Ferroptosis, driven by iron-dependent phospholipid peroxidation, is emerging as an intrinsic cancer defense mechanism. However, the regulatory networks involved in ferroptosis remain largely unknown. Here, we found that serine beta-lactamase-like protein (LACTB) inhibits liver cancer progression by regulating ferroptosis. LACTB is downregulated in liver cancer, and the ectopic expression of LACTB markedly inhibits cell viability, colony formation, and tumour growth. LACTB knockout exerts the opposite effects. Further investigation revealed that LACTB blocks HSPA8 transcription in a p53-dependent manner, resulting in the elevation of NCOA4-mediated ferritinophagy and inhibition of SLC7A11/GSH/GPX4 signalling, thereby triggering ferroptosis and suppressing liver cancer progression. Liver cancer cells with an endogenous mutation of p53 binding site in the HSPA8 promoter exhibited increased resistance to ferroptosis inducers, and the ferroptosis-promoting effect of LACTB was significantly weakened in these mutant cells. Importantly, LACTB is identified as a downstream target of lenvatinib, and adeno-associated virus-mediated overexpression and knockdown of LACTB notably enhance and attenuate the anti-tumour efficacy of lenvatinib in vivo, respectively. Taken together, our study reveals a novel action of LACTB and provides potential therapeutic strategies for enhancing the efficacy of lenvatinib in liver cancer.