Abstract 5539: Snail expression is associated with epithelial to mesenchymal transition and a poor prognosis in malignant pleural mesotheliomas

Introduction: Malignant pleural mesotheliomas (MPMs) are aggressive tumors with a poor prognosis. Regarding tumor histology, however, the survival has been reported to be lower in patients with non-epitheloid tumors than in those with epitheloid tumors. Therefore, in order to identify molecular targets for the treatment against MPM patients, we investigated several molecules associated with epithelial to mesenchymal transition, such as Snail, Twist, E-cadherin and N-cadherin. Methods: We studied one hundred and nine patients with MPMs, including 61 epitheloid tumors (55.9%), 21 sarcomatoid tumors (19.2%), 20 biphasic tumors (18.3%) and 7 desmoplastic tumors (6.4%). Immunohistochemical assays were performed to evaluate the intratumoral expressions of Snail, Twist, E-cadherin and N-cadherin. Results: Among 109 MPMs, 41 tumors (37.6%) were Snail-high tumors, 30 tumors (27.5%) were Twist-high tumors, 18 tumors (16.5%) were E-cadherin-positive tumors, and 35 tumors (32.1%) were N-cadherin-positive tumors. Regarding tumor histology, the nuclear expression of Snail expression was significantly higher in non-epithelioid tumors than in epitheloid tumors (P