Identification of Secreted Phosphoprotein 1 (SPP1) as a Prognostic Factor in Lower-Grade Gliomas

Secreted phosphoprotein 1 (SPP1) is an important extracellular glycoprotein that is associated with immune regulation, tumorigenesis, and cell signaling. However, the prognostic value of SPP1 in patients with glioma has not yet been clarified, especially in lower-grade gliomas. The objective of this study is to evaluate the prognostic merit of SPP1 in lower-grade gliomas.The messenger RNA (mRNA) expression of SPP1 in about 1000 cancer cell lines was explored by using the data from the Cancer Cell Line Encyclopedia database. The Oncomine database was mined to evaluate the mRNA expression of SPP1 in lower-grade glioma, glioblastoma, and normal brain tissues. The correlation between SPP1 mRNA expression and overall survival of patients with glioma from The Cancer Genome Atlas database was analyzed.SPP1 mRNA expression of glioma was ranked as the eighth highest of all cancer cell lines in the Cancer Cell Line Encyclopedia database. The data from the Oncomine database suggested that SPP1 expression was significantly high in glioblastoma compared with normal brain tissues but was not significantly high in lower-grade glioma compared with normal brain tissue. Analysis of the RNA-Seq data from The Cancer Genome Atlas database showed that the increased SPP1 mRNA expression in lower-grade glioma was significantly associated with poor survival outcomes in patients with lower-grade glioma. Multivariate Cox regression analysis showed that SPP1 might be considered as an independent prognostic factor in lower-grade gliomas.The present study showed that SPP1 overexpression is related to worse overall survival in patients with lower-grade glioma. Moreover, SPP1 could be considered as an independent factor in lower-grade gliomas.