Soluble Mesothelin Related Protein in Mesothelioma

Abstract

The worldwide incidence of malignant mesothelioma is increasing. This is a highly aggressive asbestos-related tumor with a median survival of less than a year.1 Treatment options have been limited and have done little to extend the median survival, although some strategies, such as complete tumor resection in patients with early disease, seem promising.2,3 Serum markers have been useful for the clinical management of different cancers.4 Currently no serum markers are in routine use for the clinical management of patients with mesothelioma. We have therefore evaluated a newly described tumor marker, soluble mesothelin related protein (SMRP),5 in patients with mesothelioma. SMRP is a member of the mesothelin family of proteins. Little is known of the function of this family of proteins. Mesothelin itself is a 40kDa cell surface protein that is present on normal mesothelial cells and on some cancers including mesothelioma, ovarian, and pancreatic cancer.6 It is believed that alternative splicing of the mesothelin gene results in the production of SMRP, a putatively soluble protein with an N-terminal region identical to that of mesothelin but with a different C-terminal. Using a doubledeterminant enzyme-linked immunosorbent assay, SMRP has been detected in the serum of patients with ovarian cancer and in a few patients with other cancers5