Calpeptin Prevents Malignant Pleural Mesothelioma Cell Proliferation via the Angiopoietin1/Tie2 System

Malignant pleural mesothelioma (MPM), an aggressive malignant tumor of mesothelial origin associated with asbestos exposure, shows a limited response to conventional chemotherapy and radiotherapy. Therefore, the overall survival of MPM patients remains very poor. Progress in the development of therapeutic strategies for MPM has been limited. We recently reported that the calpain inhibitor, calpeptin exerted inhibitory effects on pulmonary fibrosis by inhibiting the proliferation of lung fibroblasts. In the present study, we examined the preventive effects of calpeptin on the cell growth of MPM, the origin of which is mesenchymal cells, similar to lung fibroblasts. Calpeptin inhibited the proliferation of MPM cells, but not mesothelial cells. It also prevented 1) the expression of angiopoietin (Ang)1 and Tie2 mRNA in MPM cells, but not mesothelial cells and 2) the Ang1induced proliferation of MPM cells through an NFkB dependent pathway, which may be the mechanism underlying the preventive effects of calpeptin on the growth of MPM cells. These results suggest potential clinical use of calpeptin for the treatment of MPM.