HDAC2 (Histone Deacetylase 2) is a key subtype of the histone deacetylase family, widely expressed in human proliferative tissues and tumor cells. It coregulates histone acetylation modification, gene transcription, cell cycle, proliferation and apoptosis, and inflammatory responses. HDAC2 removes histone acetyl groups, remodels chromatin structure, inhibits the transcriptional expression of tumor suppressor genes and anti-inflammatory genes, and regulates cellular physiological processes. Abnormal overexpression of HDAC2 causes tumor suppressor gene silencing, sustained activation of inflammatory pathways and cell cycle disorder, continuously driving malignant tumor proliferation, inflammatory diseases and fibrotic diseases, with significant overexpression in lung cancer, liver cancer, colorectal cancer and other tumors.