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Soluble mesothelin-related peptides (SMRP) - High stability of a potential tumor marker for mesothelioma

BG Institute for Occupational Medicine (BGFA), Ruhr University of Bochum, Bochum, Germany.
Cancer biomarkers: section A of Disease markers (Impact Factor: 1.19). 02/2007; 3(6):287-92.
Source: PubMed

ABSTRACT SMRP (soluble mesothelin-related peptides) is a promising marker for detection of malignant mesotheliomas (MM) in serum that has not yet been validated in appropriate epidemiological studies. Field studies might not always provide optimal conditions for storage and transport of samples, and follow-up studies have to rely on sample integrity. Proper validation of the marker would require sufficient stability of the antigen and robustness of the assay. SMRP concentrations were evaluated in serum samples of 98 healthy donors, using the MESOMARK ELISA kit. The SMRP distribution in the healthy study population was determined and biological and pre-analytical variations were examined regarding their influence on SMRP concentrations. For diagnostic decisions a best statistical and unbiased cut-off between 1.5 and 1.6 nmol/L was determined (95th percentile). No age- or gender-specific differences could be observed. SMRP exhibits excellent stability regarding short-term storage, long-term storage, and repeated freeze/thaw cycles. Scientific studies as well as real life applications that employ SMRP would not be limited by sample stability issues.

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    ABSTRACT: ERC/mesothelin is expressed on the normal mesothelium and some cancers such as mesothelioma or ovarian carcinoma. A splicing isoform of ERC/mesothelin (known as SMRP), which has an 82-bp insertion and codes for a C-terminus with a hydrophilic, presumably soluble, tail instead of a GPI-anchoring signal, has been reported as a useful marker for the diagnosis of mesothelioma. However, the existence of SMRP has not yet been demonstrated in the serum of mesothelioma patients. To elucidate the existence of SMRP, we have established a new enzyme-linked immunosorbent assay (ELISA) system for SMRP. The ELISA study revealed that N- and C-ERC/mesothelin were detected in sera from mesothelioma patients, but not SMRP, even in these samples. This result showed that the SMRP detected with MESOMARK kit should be lack of soluble C-terminus and indistinguishable from C-ERC/mesothelin. Further study might be necessary to demonstrate the relationship between SMRP and mesothelin.
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