Abstract
Cryosections of epithelial, sarcomatoid, and biphasic malignant mesotheliomas (EMM, n = 11; SMM, n = 5; BMM, n = 6) of the pleura were immunostained with monoclonal antibodies to integrin subunits α 1–6 and v, and β 1–4. Localization patterns were compared with those known to occur in pulmonary and other adenocarcinomas (PADC, ADC). EMM and the epithelial component of BMM (ecBMM) expressed α 1,3,5,6, and v and β 1 and 4 . SMM and the sarcomatoid elements of BMM (scBMM) reacted variably for α 1,3,5,6 and v and β 1. Reactions for α 3, found in all tumors, were strongest in EMM, ecBMM, and PADC. Our findings indicate that EMM and ecBMM parallel PADC and most ADC in their expression of α 6 β 4, underscoring that this laminin integrin receptor is intimately associated with these neoplastic epithelial phenotypes. Also, our observations on α 3 β 1 suggest that this cell-cell adhesion-mediating integrin is related to the epithelial phenotype. Notably, all malignant mesotheliomas (MM), including those with distinct glandular structures, expressed the α 5 β 1 fibronectin receptor, thus paralleling most sarcomas and differing from PADC and most other ADC. We conclude that irrespective of architectural and cytologic variants, transformed mesothelial cells possess an integrin repertory that differs significantly from that of most ADC, including those of the lung. These findings set mesothelium apart from epithelia and may prove helpful as adjunct tools for the differential diagnosis between EMM and AD.
Published Version
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