Biglycan (BGN) is an extracellular matrix proteoglycan with multifaceted biological roles. As a small leucine-rich repeat proteoglycan, BGN functions as a structural component of the extracellular matrix and is involved in collagen fiber assembly and elastic fiber organization 1. BGN exhibits glycosaminoglycan binding capacity and contributes to matrix structural properties, particularly compression resistance 1. Beyond structural functions, BGN participates in cell signaling and immune regulation. In prostate cancer, BGN is secreted as a key factor regulating myeloid-derived suppressor cell (MDSC) migration through coordinated translational regulation via the MNK/eIF4E and Akt/mTOR pathways 2. BGN expression is associated with accelerated aging phenotypes, linked to age-related diseases through pro-inflammatory NF-κB pathway activation 3. In colorectal cancer, BGN serves as a fibroblast-associated prognostic biomarker; knockdown of BGN significantly impairs cancer cell proliferation, migration, and invasion 4. Similarly, in esophageal squamous cell carcinoma, BGN knockdown suppresses proliferation and migration while enhancing chemotherapy response 5. BGN mutations cause rare genetic disorders including Meester-Loeys syndrome and X-linked spondyloepimetaphyseal dysplasia, reflecting its critical role in connective tissue integrity. These findings position BGN as both a structural matrix component and an immunomodulatory factor with therapeutic potential in cancer and age-related diseases.