BACKGROUND: TRAF2 exerts important functions in regulating the development and progression of cancer. The aim of this study is to investigate whether TRAF2 is a valuable prognostic biomarker and to determine if it regulates TRAIL-induced apoptosis in prostate cancer.
MATERIAL AND METHODS: Microarray gene expression data from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were used to determine TRAF2 expression in prostate cancer. TRAF2 expression in prostate cancer was further investigated by immunohistochemistry assay. Kaplan–Meier curves and log-rank test were used to assess the recurrence-free rate. Cox regression was used to analyze prognostic factors. Effects of TRAF2 on regulating TRAIL-induced apoptosis in DU-145 cells were further investigated.
RESULTS: We found that TRAF2 was significantly upregulated in prostate cancer compared with normal prostate samples (P<0.001). In addition, compared with primary prostate cancer, TRAF2 was upregulated in metastatic prostate cancer (P=0.006). Furthermore, our results showed that high expression of TRAF2 was significantly associated with tumor stage of prostate cancer (P=0.035). TRAF2 high expression was associated with poorer recurrence-free survival in prostate cancer patients (P=0.013). TRAF2 was found to be a valuable independent prognostic factor for predicting recurrence-free survival (P=0.026). In addition, the present results indicate that TRAF2 affects TRAIL-induced apoptosis in prostate cancer DU-145 cells via regulating cleaved Caspase-8 and c-Flip expression.
CONCLUSIONS: TRAF2 could be a novel prognostic biomarker for predicting recurrence-free survival in patients with prostate cancer, which might be associated with the effects of TRAF2 in regulating TRAIL-induced apoptosis in prostate cancer cells via c-Flip/Caspase-8 signalling.

Keywords: Biological Markers, Clinical Medicine, Disease Progression, Prostatic Neoplasms, Urologic Neoplasms