HDAC2 (histone deacetylase 2) is a chr6-modifying enzyme that catalyzes the removal of acetyl groups from histone lysine residues, leading to transcriptional repression and playing crucial roles in cancer progression and therapeutic resistance 12. The enzyme functions through multiple mechanisms including direct histone deacetylation and formation of transcriptional repressor complexes. HDAC2 promotes malignant progression in various cancers by transcriptionally activating oncogenes like LAPTM4B in hepatocellular carcinoma 2 and regulating autophagy pathways. In colorectal cancer, HDAC2 epigenetically silences the pyroptosis mediator NLRP3 through H3K27 deacetylation, limiting therapeutic-induced cell death 3. The enzyme also contributes to chemotherapy resistance by mediating protein delactylation, as demonstrated in triple-negative breast cancer where HDAC2 delactylates METTL3 to enhance DNA damage repair and cisplatin resistance 4. Additionally, HDAC2 regulates angiogenesis through a feedback loop with H3K9 lactylation in endothelial cells 1. Therapeutically, HDAC2 represents a promising target, with inhibitors showing efficacy in sensitizing cancer cells to conventional therapies and alleviating pathological processes like liver fibrosis 5. High HDAC2 expression correlates with poor prognosis across multiple cancer types 23.