Malignant mesothelioma does not demonstrate overexpression or gene amplification despite cytoplasmic immunohistochemical staining for c-Erb-B2.

Abstract

Previous studies have shown conflicting results regarding the expression of c-Erb-B2 in malignant mesothelioma. Overexpression of the c-erb-B2 gene product in a subset of mesothelioma may have prognostic or therapeutic implications. To determine whether malignant mesothelioma demonstrates c-Erb-B2 overexpression and, if so, whether such overexpression correlates with gene amplification. Immunohistochemistry, reverse transcription-polymerase chain reaction, and fluorescent in situ hybridization were used to analyze archived tissue from 37 cases of malignant mesothelioma. Although immunohistochemical staining for c-Erb-B2 was detected in most mesotheliomas, the staining was cytoplasmic and was not consistent between the 2 different primary antibodies used. Moreover, even cases with strong cytoplasmic staining for c-Erb-B2 did not demonstrate increased messenger RNA levels or gene copy numbers compared to cases that demonstrated no staining. Cytoplasmic immunoreactivity for c-Erb-B2 in mesothelioma does not represent gene overexpression or amplification and may be an immunohistochemical artifact.