Clinical relevance
Malignant brain tumors, whether primary or secondary, are among the deadliest cancers with poor prognosis and short patient survival. Despite advances in understanding the driver gene mutation and heterogeneity within tumor cells, there is limited information about proteomic changes. The aim of our study was to construct a systemic proteome of those two typical malignant tumors in human brain: primary (gliomas) and secondary (brain metastases) tumors, and dig out their heterogeneities for disease type-specific diagnosis and therapy. In the current work, conserved protein patterns were found in brain metastases. Among gliomas, proteomic heterogeneities were confirmed in different grades of gliomas, which can serve as novel diagnostic biomarkers for glioma subgrouping. In addition, distinct pathway-level differences among two types of brain malignancies were firstly summarized, and five newly discovered proteins were recognized as candidate biomarker to discriminate primary and secondary tumors.