Establishment and preliminary characterization of human malignant mesothelioma cell lines

Malignant mesothelioma is an aggressive and rare tumor of the mesothelium which arises in serosal cavities and is strongly related to asbestos exposure. The incidence of this tumor is still increasing because of the widespread use of asbestos over the past years and the long latency of this malignancy. The paucity of well-characterized in vitro human models and the consequent shortage of experimental pharmacological studies on mesothelioma reduce the success of its clinical management. It is well known that established human cell lines represent a rapid and advantageous system for in vitro studies of several diseases, such as mesothelioma. Thus, the aim of our study was to establish and characterize a panel of selected human malignant mesothelioma cell lines in order to highlight the biology of this tumor and to test the effectiveness of new antiproliferative compounds. During the last year, we collected 10 pleural effusion samples from patients with diagnosed and pharmacologically untreated mesothelioma. Among these, we were able to isolate three continuously growing cell lines, identified as IST-Mes1, IST-Mes2 and IST-Mes3. Another previously established malignant mesothelioma cell line (MPP89) has also been included in this study. The cells in culture appeared morphologically heterogeneous: three of them (IST-Mes1, IST-Mes2, and MPP89) were spindle-shaped, and upon reaching confluence, they assumed the characteristic cobblestone-like pattern, whereas IST-Mes3 showed mixed sizes and shapes. Cell growth studies revealed that all cell lines reach exponential growth phase within 4-7 days after plating with a doubling time ranging from 37-87 hours. Finally, insulin-like growth factor-I did not stimulate cellular proliferation of both the IST-Mes1 and IST-Mes2 cell lines.