Secreted phosphoprotein 1 (Osteopontin) (SPP1)

Osteopontin (OPN), also known as Secreted phosphoprotein 1 (SPP1), is a multifunctional, highly acidic glycophosphoprotein that belongs to the SIBLING (Small Integrin-Binding Ligand, N-linked Glycoprotein) family (UniProt P10451). It is expressed by various cell types, including osteoblasts, macrophages, and activated T cells, and is found in both the extracellular matrix and biological fluids (PubMed: 25614319). OPN functions as a bridge between cells and the matrix by binding to several integrin receptors (notably αvβ3) and CD44, thereby regulating cell adhesion, migration, and survival (PubMed: 15334120). In disease states, OPN is frequently overexpressed and serves as a key driver of chronic inflammation, tissue fibrosis, and cancer progression, where it promotes tumor metastasis and angiogenesis (PubMed: 21460874). Therapeutic development targeting OPN includes monoclonal antibodies and aptamers designed to block its pro-inflammatory and pro-metastatic signaling, though its diverse physiological roles necessitate careful safety monitoring (PubMed: 29211045).

Other names

OsteopontinSPP1Bone sialoprotein IBNSPEarly T-lymphocyte activation 1 proteinETA-1NephropontinUrinary stone protein

Inhibition of osteopontin binding to integrin receptors (αvβ3, αvβ1, αvβ5) and CD44; neutralization of soluble osteopontin to prevent pro-inflammatory and pro-metastatic signaling.