Novel orthotopic implantation model of human malignant pleural mesothelioma (EHMES-10 cells) highly expressing vascular endothelial growth factor and its receptor

Malignant pleural mesothelioma (MPM) is closely related to exposure to asbestos, and a rapid increase in the number of MPM patients in Japan is estimated in the years 2010-2050. The purpose of the present study was to establish a clinically relevant animal model that shows human patient-like progression of MPM. Here, we demonstrate that a human MPM cell line (EHMES-10) inoculated orthotopically (thoracic cavity) into severe combined immunodeficiency (SCID) mice produces highly vascularized thoracic tumors with pleural dissemination and bloody pleural effusions by 5 weeks, suggesting a patient-like progression of this cell line after orthotopic inoculation. EHMES-10 cells overexpressed vascular endothelial growth factor (VEGF), a molecule responsible for malignant effusions, and its receptor. Treatment with cisplatin, but not gemcitabine, significantly inhibited the production of pleural effusions, but it was not effective for thoracic tumors, consistent with chemotherapy refractory characteristics of MPM in patients. Our patient-like orthotopic model using EHMES-10 cells overexpressing VEGF and its receptor may be useful for examining the molecular pathogenesis of MPM and may contribute to the development of novel treatment strategies for MPM.