HSP90α-USP7-DNMT1 axis drives HCC recurrence after microwave ablation by disrupting ACSS3-mediated propionate metabolism.

Insufficient microwave ablation (iMWA) of hepatocellular carcinoma (HCC) often leads to rapid and aggressive recurrence, and effective intervention remains a formidable challenge. Here, we show that the DNA methylation machinery is aberrantly activated in residual HCC following iMWA. The heat-responsive stress protein HSP90α collaborates with the deubiquitinase USP7 to stabilize and upregulate DNA methyltransferase DNMT1, thereby transducing the sublethal heat-stress input from iMWA into an epigenetic output and elevating DNA methylation levels. Sublethal heat-stress-induced DNMT1 upregulation significantly promotes the growth and invasive potential of post-iMWA residual HCC cells, a process that involves disruption of propionate metabolism. Mechanistically, the propionate-metabolizing enzyme ACSS3 in residual HCC is found to be silenced by DNMT1-mediated promoter hypermethylation, impairing propionate-to-propionyl-coenzyme A (CoA) conversion. Reduction in propionyl-CoA production enhances the activity of the fatty acid β-oxidation (FAO) rate-limiting enzyme carnitine palmitoyltransferase 1 (CPT1), ultimately stimulating FAO-dependent ATP regeneration. Critically, we developed a liposomal CRISPR-dCas9-based locus-specific demethylation system for precise epigenetic reactivation of ACSS3 and demonstrated its ability to effectively prevent post-iMWA HCC recurrence and metastasis, with more pronounced efficacy when combined with propionate supplementation. Our findings identify a novel DNMT1-driven "epigenetic-metabolic cascade" as a central mechanism promoting HCC recurrence following iMWA, emphasizing the therapeutic potential of ACSS3-targeted methylation editing.