Identification of Secreted phosphoprotein 1 (SPP1) as a prognostic factor in lower-grade gliomas

Abstract Objective 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 glioma patients 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. Methods The mRNA expression of SPP1 in about 1,000 cancer cell lines was explored by using the data from Cancer Cell Line Encyclopedia (CCLE) database. 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 glioma from The Cancer Genome Atlas (TCGA) database was analyzed. Results SPP1 mRNA expression of glioma was ranked as the eighth highest of all cancer cell lines in the CCLE database. The data from Oncomine database suggested that SPP1 expression was significantly high in glioblastoma when compared with normal brain tissues but was not significantly high in lower-grade glioma when compared with normal brain tissue. Analysis of the RNA-seq data from TCGA showed that the increased SPP1 mRNA expression in lower-grade glioma was significantly associated with poor survival outcomes in lower-grade glioma patients. Multivariate Cox regression analysis showed that SPP1 might be considered as an independent prognostic factor in lower-grade gliomas. Conclusions The present study showed that SPP1 over-expression is related with worse overall survival in lower-grade glioma. Moreover, SPP1 could be considered as an independent factor in lower-grade gliomas.