SPP1/Osteopontin in Oncology: A Multifaceted Player in Tumor Progression

Secreted Phosphoprotein 1 (SPP1), also known as Osteopontin (OPN), is a multifunctional glycoprotein widely involved in biological processes such as cell adhesion, migration, signal transduction, and immune regulation. Studies have shown that SPP1 is highly expressed in various tumors and is closely associated with tumor invasion, metastasis, and poor prognosis. Additionally, SPP1 can help tumor cells evade immune surveillance by regulating the function of immune cells in the tumor microenvironment. This article reviews the research progress of SPP1 in tumors from three aspects: first, the molecular biological characteristics of SPP1; second, the clinical value of SPP1 as a prognostic marker in various tumors, analyzing the correlation between its expression levels and patient prognosis; and finally, the mechanisms of SPP1 in the tumor microenvironment. Through this review, we aim to provide a theoretical foundation for a deeper understanding of the role of SPP1 in tumor development and to offer new insights and directions for developing SPP1-based tumor diagnostic markers and targeted therapeutic strategies.