CPNE1 Is a Useful Prognostic Marker and Is Associated with TNF Receptor-Associated Factor 2 (TRAF2) Expression in Prostate Cancer

BACKGROUND CPNE1 plays a vital role in regulating cell differentiation. The clinical and biological values of CPNE1 in prostate cancer are still unclear. The aim of this study was to investigate the clinicopathological value of CPNE1 and the association of CPNE1 with TRAF2 expression in patients with prostate cancer. MATERIAL AND METHODS CPNE1 expression in prostate cancer was analyzed using Gene Expression Omnibus (GEO) databases. The Cancer Genome Atlas (TCGA) dataset was used to investigate the association of CPNE1 expression with TRAF2 expression in prostate cancer. The association of CPNE1 expression with recurrence-free survival in patients was also analyzed using the TCGA dataset. Immunohistochemistry assay was performed to examine CPNE1 expression in 65 normal prostate samples and 114 prostate cancer samples. The recurrence-free survival in patients was evaluated using Kaplan-Meier curves and log-rank test. In addition, multivariate and univariate analyses of prognostic factors were investigated by Cox regression. The effect of CPNE1 on TRAF2 expression was explored in human prostate cancer DU-145 cells. RESULTS Our results showed that expression level of CPNE1 is higher in prostate cancer than in normal prostate tissues (P=0.006). In the GSE35988 dataset, CPNE1 expression was found to be upregulated in castration-resistant prostate cancer compared with non-castration-resistant prostate cancer (P<0.001). Furthermore, we found that CPNE1 high expression was significantly related to tumor stage, Gleason score, and poorer biochemical recurrence-free survival in prostate cancer patients. Co-expression analysis of TCGA data showed that CPNE1 is significantly associated with TRAF2 expression. CPNE1 overexpression can upregulate TRAF2 expression in prostate cancer DU-145 cells as determined by Western blotting and immunofluorescence assays. CONCLUSIONS Overall, our findings suggest that CPNE1 is a valuable prognostic marker for evaluating recurrence-free survival and is positively related to TRAF2 expression in prostate cancer.