Project description:Introduction: Malignant pleural mesothelioma (MPM) is an aggressive malignancy with poor prognosis. Unlike many other cancers, MPM is mostly characterized by inactivation of tumor suppressor genes. Its highly malignant nature in absence of tumor driving oncogene mutations indicates an extrinsic supply of stimulating signals by cells of the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are an abundant cell type of the TME and have been shown to drive the progression of several cancer types. The aim of the current study was to isolate and characterize patient-derived mesothelioma-associated fibroblasts (Meso-CAFs), and evaluate their impact on MPM cells. Methods: Meso-CAFs were isolated from surgical specimens of MPM patients and analyzed by comparative genomic hybridization, transcriptomics and proteomics. Human MPM cell lines were retrovirally transduced with GFP. The impact of Meso-CAFs on tumor cell growth, migration, and response to pathway inhibitors and cisplatin was investigated in 2D and 3D co-culture models by videomicroscopy and automated image analysis. Results: Meso-CAFs possess normal genomes without gene copy number aberrations typical for MPM cells. They express CAF markers and lack MPM marker expression. Their proteome and secretome profiles clearly differ from normal lung fibroblasts with particularly strong differences in the fraction of actively secreted proteins. The presence of Meso-CAFs in co-culture resulted in increased proliferation and migration of MPM cells. A similar effect on cell growth was induced by conditioned medium. Met/PI3K or WNT signaling inhibition abolished the Meso-CAF-mediated growth stimulation. While Meso-CAFs reduced the efficacy of EGFR inhibition in co-cultures, they did not provide protection of tumor cells against cisplatin. Conclusion: Our study provides the first characterization of human patient-derived Meso-CAFs and demonstrates a strong impact of Meso-CAFs on tumor cell growth and migration, two key aspects of MPM aggressiveness, indicating a substantial role of Meso-CAFs in driving MPM progression. Moreover, we show that Meso-CAFs significantly influence drug response and identify signaling pathways required for Meso-CAF-mediated growth stimulation. These data could be relevant for improving therapeutic strategies in MPM.

Project description:Malignant pleural mesothelioma (MPM) is a highly lethal, poorly understood neoplasm that is typically associated with asbestos exposure. We performed transcriptional profiling using high-density oligonucleotide microarrays containing approximately 22,000 genes to elucidate potential molecular and pathobiological pathways in MPM using discarded human MPM tumor specimens (n=40), normal lung specimens (n=4), normal pleura specimens (n=5), and MPM and SV40-immortalized mesothelial cell lines (n=5). In global expression analysis using unsupervised clustering techniques, we found two potential subclasses of mesothelioma which correlate loosely with tumor histology. We also identified sets of genes with expression levels that distinguish between multiple tumor subclasses, normal and tumor tissues, and tumors with different morphologies. Microarray gene expression data were confirmed using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and protein analysis for three novel candidate oncogenes (NME2, CRI1, and PDGFC) and one candidate tumor suppressor (GSN). Finally, we used bioinformatics tools (i.e. software) to create and explore complex physiological pathways that may be relevant in mesothelioma tumorigenesis, pathobiology, or both. Tissues and cell lines profiled using microarrays. Discarded MPM surgical specimens (n=40), normal pleura specimens (n=5), and normal lung specimens (n=4) were freshly collected (and snap frozen) from patients who underwent surgery at Boston's Brigham and Women's Hospital (BWH) between October 1998 and August 2000. All of these patients underwent extrapleural pneumonectomy with heated intra-pleural cisplatin chemotherapy delivered after the specimens were removed. All normal specimens were obtained from patients who were never diagnosed with MPM. Two human MPM cell lines (MS589 and MS428) were kindly provided by Jonathan A. Fletcher, M.D., Department of Pathology, BWH. The JMN1B MPM cell line19,20 has been described previously. The SV40-immortalized, non-tumorigenic mesothelial cell line (Met-5A)21 and the MPM cell line MSTO-211H22 were purchased from the American Type Culture Collection. Normal tissues were obtained from additional consented patients undergoing treatment for diseases other than MPM. All MPM samples used in these studies contained relatively pure tumor (greater than 50% tumor cells per high power field examined in a section adjacent to the tissue used). The microscopic slides from the patients' resection specimens were reviewed by one of the authors (J.G.), and the diagnosis and histologic subclassification of MPM confirmed in all cases. Linked clinical and pathological data were obtained for all patients who contributed tumor specimens. Specimens and data were rendered anonymous to protect patient confidentiality. Studies utilizing human tissues were approved by and conducted in accordance with the policies of the Institutional Review Board at BWH.

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A novel therapeutic strategy targeting the mesenchymal phenotype of malignant pleural mesothelioma by suppressing LSD1 [array]

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