High expression of mesothelin in plasma and tissue is associated with poor prognosis and promotes invasion and metastasis in gastric cancer

Mesothelin (MSLN), a tumor-associated antigen, is upregulated in various malignancies, including gastric cancer (GC). In addition, MSLN is found in the blood-stream of affected individuals, where it is referred to as soluble MSLN-related protein (SMRP). This study aims to investigate the role of MSLN in GC and evaluate its potential as a plasma biomarker for diagnosis and prognosis. Toward that end, GC tissues were obtained, upon signed consent, from affected individuals undergoing surgery or endoscopy (n = 82). Quantitative RT-PCR and immunohistochemistry were performed to determine MSLN expression. Simultaneously, The Cancer Genome Atlas (TCGA) database was mined to evaluate global status of MSLN gene expression in gastric cancer. Next, in vitro cell-culture studies were conducted to evaluate MSLN-driven proliferation properties. Using ELISA, sera from 55 GC-affected individuals were tested for MSLN level. Additionally, plasma mesothelin levels were compared in 6 cases before and after surgery. Upregulated MSLN expression was found in GC tissues, compared to adjacent normal tissues (p