Celastrol induces lipid-associated stress and apoptosis in EBV-positive extranodal NK/T-cell lymphoma with NCOR2-HDAC3 perturbation.

Epstein-Barr virus (EBV)-positive extranodal natural killer/T-cell lymphoma (ENKTL) remains difficult to treat after relapse or refractory progression. We investigated celastrol-associated chromatin, lipid-metabolic, and stress responses in ENKTL cell-line models. Celastrol reduced SNK6 and SNT8 cell viability, increased apoptotic protein processing, and suppressed short-term SNK6 xenograft growth with increased histological markers of apoptosis. Chemical proteomics identified nuclear receptor corepressor 2 (NCOR2) and nuclear receptor corepressor 1 (NCOR1) among celastrol-associated proteins, and pull-down immunoblotting confirmed NCOR2 recovery. Probe recovery mapped to an NCOR2 region containing the deacetylase activation domain. Celastrol altered NCOR2 thermal stability, reduced its co-immunoprecipitation with histone deacetylase 3 (HDAC3), and inhibited recombinant HDAC3/NCOR2 activity. Histone H3 lysine 27 acetylation (H3K27ac) profiling at 2 h and RNA sequencing at 24 h revealed chromatin redistribution and associated stress-response and lipid-metabolic transcriptional changes. Selected apoptotic, lipid-metabolic, and stress-response protein changes were reproduced in SNT8 cells. In SNK6 cells, the HDAC3 inhibitor RGFP966 partially phenocopied selected celastrol-associated changes. NCOR2 depletion reduced lipid-metabolic enzyme expression and enhanced apoptotic-marker accumulation during celastrol treatment, whereas oleic acid conjugated to bovine serum albumin partially attenuated stress and apoptotic responses. Bulk RNA sequencing showed no coordinated induction of the examined EBV lytic-associated transcripts. These findings identify NCOR2-HDAC3-associated perturbation and lipid-associated stress as components of the celastrol response in EBV-positive ENKTL models.