S100P, a potential novel prognostic marker in colorectal cancer.

Previous studies have shown that S100P contributes to the development of a number of tumors. However, its prognostic significance in colorectal cancer (CRC) has not been demonstrated. This study aimed to confirm the expression of S100P in colorectal cancer as well as the epigenetic mechanism underlying its gene expression, and to demonstrate whether S100P could be used to predict prognosis as a biomarker. We tested the expression of S100P in 96 CRCs and their paired tissue controls, as well as 13 colon cancer cell lines by RT-PCR and western blotting. Expression of the S100P protein and mRNA was significantly higher in cancerous regions compared to that in paired non-cancerous tissues (P=4.59 x 10(-17), 0.005 respectively). The expression was significantly correlated with the hypomethylation of the S100P promoter (P=4.92 x 10(-5)), which was detected by bisulphite sequencing PCR (BSP) and quantitative methylation-specific real-time PCR (QMSP). In stages I to III, the patients with positive expression of S100P protein showed poorer overall survival compared to those with S100P negative expression, P=0.031. We also measured the preoperative serum S100P levels by ELISA. The patients with normal serum levels of S100P showed favorable prognosis compared with patients with elevated S100P levels (P=0.008). These data suggest that S100P protein may be a potential novel prognostic biomarker in CRC patients.