Glycodelin is a potential novel follow-up biomarker for malignant pleural mesothelioma

Abstract

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor with a short survival time arising from the mesothelial cells of the pleura. Soluble mesothelin-related peptide (SMRP), osteopontin or EFEMP1 (Fibulin-3) are well described biomarkers for malignant mesothelioma with moderate sensitivity and specificity. In this study, we characterized the expression of glycodelin, a marker for risk pregnancy, in MPM by RNA and protein analyses and investigated its potential as a MPM biomarker. We were able to detect glycodelin in the serum of MPM patients. Compared to benign lung diseases, the serum levels were significant increased. Patients with high glycodelin serum levels revealed a worse overall survival. The glycodelin serum levels correlated with the tumor response to treatment. A comparison of SMRP and glycodelin serum measurement in a large patient cohort demonstrated that the detection of both soluble factors can increase the reliable diagnostic of MPM. Glycodelin was highly expressed in MPM tumors. Analyses of a tissue micro array indicated that the immunomodulatory form glycodelin A was expressed in MPM and correlated with the survival of the patients. Altogether, glycodelin seems to be a new potential biomarker for the aggressive malignant pleural mesothelioma.

Keywords: MPM; SMRP; biomarker; follow-up; glycodelin.

Figure 1. Detection of glycodelin in serum of patients with lung diseases

A., detection of glycodelin in serum of patients with different benign and malignant lung diseases. B., comparison of glycodelin serum levels in mesothelioma, NSCLC and benign inflammatory lung diseases (please note that the NSCLC and the COPD cohorts are described elsewhere (22)). ILD = Interstitial Lung Diseases, UIP = Usual Interstitial Pneumonia, LC = Lung Cancer, Met = Metastasis, NSCLC = Non-small Cell Lung Cancer, COPD = Chronic Obstructive Pulmonary Disease.

Figure 2. Glycodelin vs SMRP

A., Glycodelin and SMRP serum concentrations in patients with mesothelioma and pleurisy. B. and C., Receiver operating characteristic (ROC) analyses with glycodelin in MPM and NSCLC. The benign cohort included all benign cases of figure 1A and B. D., E. and G., survival analyses of the pretherapeutic cohort depending on glycodelin or SMRP serum concentration and a combination of both. F., correlation analyses of glycodelin and SMRP of the pretherapeutic cohort. SMRP = Soluble Mesothelin-Related Peptides

Figure 3. Glycodelin in MPM follow up serum samples

Comparison of glycodelin and SMRP serum concentrations before treatment and during the clinical follow up of six patients with an epithelial MPM. SMRP = Soluble Mesothelin-Related Peptides.

Figure 4. Glycodelin gene (PAEP) and protein expression in MPM

A., relative PAEP expression in patients with MPM compared to non-malignant mesothelial cells. Please note that a higher Ct value indicates a lower gene expression. C., glycodelin protein expression in 12 primary homogenized MPM tissues. β-actin was used as a loading control.

Figure 5. Glycodelin staining in MPM

Staining of glycodelin in two representative tumours with a polyclonal glycodelin and a monoclonal glycodelin A antibody.

Figure 6. Analyses of a MPM tissue microarray (TMA)

A., results of TMA scoring with either the polyclonal N-20 or the monoclonal A87-B/D2 glycodelin antibody stained mesothelioma patients (n = 214). B., correlation between N-20 and A87-B/D2 stainings. C., distribution of scoring. D. and E., survival analyses depending on glycodelin staining intensities and antibodies.