Glycoprotein nonmetastatic melanoma protein B (GPNMB) (GPNMB)

Glycoprotein nonmetastatic melanoma protein B (GPNMB), also known as osteoactivin or DC-HIL, is a type I transmembrane glycoprotein that plays multifaceted roles in cell adhesion, migration, and tissue repair [1, 2]. It is characterized by an extracellular domain containing an RGD motif for integrin binding and a polycystic kidney disease (PKD) domain, which together facilitate interactions with the extracellular matrix and neighboring cells [1, 4]. While GPNMB is physiologically expressed in melanocytes, osteoblasts, and macrophages to regulate bone mineralization and immune responses, it is significantly overexpressed in various high-grade malignancies, including triple-negative breast cancer, melanoma, and glioblastoma [1, 7, 10]. In these contexts, it acts as a pro-tumorigenic factor by promoting invasion, metastasis, and the recruitment of immunosuppressive cells to the tumor microenvironment [1, 9]. Beyond oncology, GPNMB has emerged as a critical biomarker for lysosomal storage disorders like Gaucher disease and neurodegenerative conditions such as Parkinson's disease, where its levels correlate with disease severity and lysosomal dysfunction [13, 17]. Therapeutic development primarily targets the cell-surface protein using antibody-drug conjugates (ADCs) like glembatumumab vedotin, which utilize the high tumor-specific density of GPNMB to deliver cytotoxic payloads directly into cancer cells [6, 9, 11]. Clinical and research efforts continue to explore GPNMB as both a prognostic indicator and a target for disrupting tumor progression, though development must carefully manage off-target toxicities related to its endogenous expression in skin and bone [8, 18].

Other names

OsteoactivinDC-HILHGFINHematopoietic growth factor inducible neurokinin-1 type receptorTransmembrane glycoprotein NMBGlycoprotein nmbPLCA3

Antibody-drug conjugate (ADC) binds to the extracellular domain of GPNMB on the cell surface, leading to internalization and intracellular release of a cytotoxic payload (e.g., MMAE) that induces cell cycle arrest and apoptosis [6, 9].