Esophageal cancer is one of the most common cancers worldwide, and the incidence and mortality is increasing rapidly in recent years in China, but the underlying mechanisms are largely unclear. Herein we used immunohistochemical staining on an esophageal squamous cell carcinoma (ESCC) tissue microarray (TMA) containing 362 cases of ESCC and found that the expression of PRSS8, serine protease prostasin, was significantly decreased in ESCC. Interestingly, the reduction of PRSS8 was well correlated with poor differentiation, less stromal lymphocyte infiltration, and shorter survival time. PRSS8 mRNA levels were also significantly reduced in ESCC compared to the adjacent normal esophagus assayed by quantitative real-time PCR. Methylation specific PCR showed that PRSS8 promoter region was hypermethylated in ESCC tissues and cell lines, which was associated with downregulation of PRSS8 expression and decreased activities of PRSS8 promoter. Promoter deletion and truncation approaches showed that the CpG island in PRSS8 promoter region played an important role on the determination of promoter activities. De-methylation agent decitabine was able to restrore PRSS8 expression in esophageal cancer cell lines, leading to the inhibition of cancer cell proliferation, motility, migration and cell cycle arrest. However, the restoration of PRSS8 and its tumor inhibition could be reversed by small interfering RNA targeting PRSS8. Immunoblotting results showed that tumor inhibition of PRSS8 may be associated with proliferation- and epithelial-mesenchymal transition - related proteins (e.g. upregulation of E-cadherin and downregulation of Twist and Snail) in ESCC cells. The findings from current study strongly suggested that PRSS8 acted as a tumor suppressor and PRSS8 promoter region hypermethylation has clinical significance of in ESCC.

Citation Format: Yonghua Bao, Qian Wang, Wancai Yang. PRSS8 methylation and its significance in esophageal squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4467.