Expression of carbonic anhydrase IX (CAIX) in malignant mesothelioma. An immunohistochemical and immunocytochemical study
Abstrakt
Malignant mesothelioma is an aggressive tumor with a poor prognosis. Carbonic anhydrase IX (CAIX) is a membranously located metalloenzyme involved in pH homeostasis with influence on regulation of cell proliferation, oncogenesis and tumor progression.
Much attention has been paid recently to carboanhydrases and their inhibitors as they offer an opportunity for both developing novel anticancer drugs, as well as diagnostic and prognostic tools. This study was designed to assess the expression of CAIX in malignant pleural and peritoneal mesotheliomas, their benign counterparts, and in pleural effusions from patients with malignant mesothelioma, metastatic carcinoma or a benign disease.
Tissue blocks from 51 malignant mesotheliomas of pleura (47 cases; 41 epithelioid, 2 biphasic, 4 sarcomatoid) and peritoneum (4 cases; all epithelioid), 14 cases with normal or reactive pleural tissue, and 19 cell blocks were analyzed. CAIX expression was determined using immunohistochemistry and its membranous immunoreactivity was semiquantitatively evaluated.
Specimens were divided into five subgroups according to the staining pattern and intensity. Overall, 92.2% (47/51) of mesotheliomas expressed CAIX.
All epithelioid mesotheliomas showed CAIX positivity, which was predominantly strong and diffuse (73.3%, 33/45). Sarcomatoid mesotheliomas and sarcomatoid areas in biphasic mesotheliomas were negative.
A strong diffuse staining was observed in all cases of normal mesothelia. In pleural effusions, CAIX expression was observed in malignant cells as well as in benign mesothelial cells.
In conclusion, CAIX is expressed virtually in all mesotheliomas except for sarcomatoid subtype, and in benign mesothelia.