TRIM28 as an independent prognostic marker plays critical roles in glioma progression

Tripartite motif (TRIM) proteins are involved in tumorigenesis. Here, we examined the expression, biological function, and clinical significance of tripartite motif containing 28 (TRIM28) in glioma, a locally aggressive brain tumor. First, TRIM28 expression was significantly higher in glioma (n = 138) than in non-glioma controls (n = 6). TRIM28 expression was positively correlated with tumor malignancy, and associated with poor overall survival (OS) and progression-free survival (PFS). Notably, TRIM28 expression was negatively correlated with p21 expression in patients with glioblastoma multiforme (GBM). A multivariate analysis that included relevant measures indicated that high TRIM28 expression is an independent prognostic factor for poor OS and PFS in GBM patients. In experiments with cultured glioma cells, down-regulating TRIM28 with shRNA increased p21 expression, and induced cell cycle arrest at the G1 phase. In a xenograft model, down-regulating TRIM28 suppressed tumor growth. These results indicate that over-expression of TRIM28 is associated with poor outcome in glioma patients.