The clinical and prognostic significance of paraoxonase-2 in gastric cancer patients: immunohistochemical analysis.

Paraoxonase-2 (PON2) belongs to the paraoxonase (PON) protein family. Unlike paraoxonase-1 (PON1), the expression and significance of PON2 remained largely unknown in gastric cancer (GC). Thus, the purpose of our study was to investigate the role of PON2 in GC. First, we found PON2 expression was obviously increased in GC samples compared with paired normal tissue samples at The Cancer Genome Atlas (TCGA) database. Then the high expression status of PON2 mRNA and protein in GC tissues was confirmed by RT-qPCR and immunohistochemistry. Furthermore, we performed the immunohistochemical analysis to study the correlation between PON2 expression and clinicopathological parameters of GC patients, and found high PON2 expression had significantly positive association with diffuse type, clinical stage, tumor invasion, lymph node metastasis and distant metastasis in GC patients. Moreover, survival analysis suggested GC patients with high PON2 expression resulted in a remarkably shorter overall survival compared with GC patients with low PON2 expression, and high expression of PON2 acted as an unfavorable predictor for overall survival. The in vitro studies indicated that silencing of PON2 expression inhibited GC cell proliferation, migration and invasion. In conclusion, our findings give first evidence that PON2 serves as oncogene in GC.