Bone sialoprotein (IBSP) (BSP)

Bone sialoprotein (BSP), also known as Integrin-binding sialoprotein (IBSP), is a major non-collagenous structural glycoprotein of the bone matrix and a member of the SIBLING (Small Integrin-Binding Ligand, N-linked Glycoprotein) family [UniProt: P21815]. It is primarily synthesized by skeletal-associated cells such as osteoblasts, osteocytes, and odontoblasts, where it plays a crucial role in the nucleation of hydroxyapatite crystals during bone mineralization and mediates cell attachment through its RGD (Arg-Gly-Asp) motif [PMID: 10750597]. In oncology, BSP is significantly upregulated in various malignant tumors, particularly those with a high affinity for bone metastasis, such as breast, prostate, and lung cancers, where it facilitates tumor cell adhesion and the formation of osteolytic lesions [PMID: 10863538]. The term "bone sialoprotein promoter–positive cancer cells" refers to a therapeutic strategy that utilizes the BSP gene promoter to drive the selective expression of "suicide genes" (like HSV-tk) or oncolytic viruses specifically within these metastatic cells [PMID: 10863538]. This approach aims to exploit the tumor-specific activation of the BSP promoter to achieve targeted cytotoxicity while minimizing systemic side effects, although potential cross-reactivity with normal bone-forming cells remains a significant clinical challenge.

Other names

Integrin-binding sialoproteinIBSPBone sialoprotein IIBSP IIBNSP

Promoter-driven selective expression of therapeutic genes or oncolytic viral replication in BSP-expressing cells; antibody-mediated inhibition of integrin-matrix interactions.