Gene expression profiling of human mesothelioma cell lines derived from pleural effusions

Malignant pleural mesothelioma (MPM) is an asbestos-related lethal malignancy refractory to conventional therapies. Since its symptoms are not specific, MPM can be easily confused with other chest diseases, especially metastatic lung adenocarcinomas (ADCA), and diagnosis is often established late when the disease is at an advanced stage. Classically, a reliable diagnosis requires histological analysis of multiple pleural biopsies. However, there is still no absolute marker for MPM. Thus, with the aim of identifying novel markers with higher specificity and sensitivity, gene expression profiling studies have been conducted using tumor specimens. Because of the cell heterogeneity of tumor samples, we decided to apply counterflow centrifugal elutriation to isolate cancer cells from pleural effusions, which are a common feature of MPM and ADCA. We profiled a total of 54 biological samples corresponding to triplicates of 13 MPM and 4 ADCA as well as the SV40-immortalized cell line MeT-5A. Our microarray results confirmed some of the existing markers which are currently used to distinguish MPM from ADCA by immunostaining of pleural biopsies and which have also been proposed for use in a PCR-based assay. Of particular interest, we also identified novel cellular markers (including predominantly COL3A1, OSAP, OCIAD2, XAGE1), which we validated by real time RT-PCR, and novel soluble markers, such as osteonectin and galectin-3, whose clinical utility as molecular targets remains to be determined. Keywords: cell type comparison three-condition experiment: ADCA vs MPM vs Met5A cells 13 MPM, 4 ADCA and Met5A were independantly grown and harvested 3 biological replicates per cell line, one replicate per array