Abstract 3257: ERC/mesothelin is expressed in human gastric cancer tissues and cell lines

Abstract

Abstract Background: ERC/mesothelin is expressed in mesothelioma and other malignancies. The ERC/mesothelin gene (MSLN) encodes a 71 kDa precursor protein, which is cleaved to yield 31 kDa N-terminal (N-ERC/mesothelin) and 40 kDa C-terminal (C-ERC/mesothelin) proteins. N-ERC/mesothelin is a soluble protein and has been reported to be a diagnostic serum marker of mesothelioma and ovarian cancer. Gastric cancer tissue also expresses C-ERC/mesothelin, but the significance of serum N-ERC levels for diagnosing gastric cancer has not yet been studied. We examined the latter issue in this study as well as C-ERC/mesothelin expression in human gastric cancer tissues and cell lines. Methods: We immunohistochemically examined C-ERC/mesothelin expression in tissue samples from 50 cases of gastric cancer, and we also assessed the C-ERC/mesothelin expression of 6 cancer cell lines (MKN-1, MKN-7, MKN-74, NUGC-3, NUGC-4 and TMK-1) using the reverse transcription-polymerase chain reaction, flow cytometry, immunohistochemistry, and immunoblotting. We also examined the N-ERC/mesothelin concentrations of the supernatants of cultured cells and the sera of gastric cancer patients using an ELISA. Results: N-ERC/mesothelin was detected in the supernatants of 3 cell lines (MKN-1, NUGC-4, and TMK-1) by ELISA, but its concentration in the sera of gastric cancer patients was almost same as that observed in the sera of the normal controls. In the gastric cancer tissues, C-ERC/mesothelin expression was associated with lymphatic invasion, as reported by Einama et al. Conclusion: N-ERC/mesothelin was secreted into the supernatants of gastric cancer cell lines, but did not appear to be a useful serum marker of gastric cancer. Citation Format: Tomoaki Ito, Kazunori Kajino, Masaaki Abe, Koichi Sato, Hiroshi Maekawa, Mutsumi Sakurada, Hajime Orita, Ryo Wada, Yoshiaki Kajiyama, Okio Hino. ERC/mesothelin is expressed in human gastric cancer tissues and cell lines. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3257. doi:10.1158/1538-7445.AM2014-3257