Identification of novel markers for malignant pleural mesothelioma diagnosis

Diagnosis of malignant pleural mesothelioma (MPM) is difficult, the most common differential diagnosis being benign pleural diseases and metastatic adenocarcinomas. In order to identify novel markers able to improve diagnostic accuracy, we performed a genome-wide gene expression analysis on tumor cells lines established from pleural effusions (13 MPM and 4 lung adenocarcinoma). Our microarray analysis led to the identification of genes encoding novel cellular and soluble markers whose expression was validated by RT-qPCR. Immunohistochemical staining of tumor biopsies with anti-type-III collagen antibodies were positive in mesothelioma cells but not in adenocarcinoma cells. Using ELISA, we showed that the C-C motif chemokine 2 (CCL2) concentration was significantly higher in pleural effusions from patients with mesothelioma (n = 61) than in subjects with adenocarcinoma (n = 25) or with benign pleural effusions (n = 15): median (interquartile range) = 2.99 ng/mL (1.76-6.01) versus 0.99 ng/mL (0.51-1.83) and 1.47 ng/mL (0.80-1.56), respectively, P < 0.0001. Conversely, the galectin-3 concentration was lower in mesothelioma: 11.50 ng/mL (6.73-23.53) versus 24.74 ng/mL (20.42-70.35) and 17.64 ng/mL (14.81-24.68), respectively, P < 0.0001. The AUC for CCL2 were 0.8030 and 0.7716 for differentiating mesothelioma from adenocarcinoma or benign effusions, respectively. Similarly, the AUC obtained for galectin-3 were 0.7980 and 0.6923, respectively. In conclusion, type-III collagen, CCL2 and galectin-3 are promising new diagnostic markers for mesothelioma. two-condition experiment: ADCA vs MPM cell lines 13 MPM and 4 ADCA cell lines were independantly grown and harvested 3 biological replicates per cell line, one replicate per array