E-Cadherin in human brain tumours: loss of immunoreactivity in malignant meningiomas.

Cadherins are a family of glycoproteins that are associated with cell adhesion mechanisms. They are divided into subclasses. The E- and P-cadherins are regarded as the epithelial subtype. Their expression has been demonstrated in many different carcinoma types. Using immunomorphological techniques, we studied the expression of E-cadherin in a series of 145 human brain tumours with the monoclonal antibody 5H9. Western blot analysis was used to confirm the immunohistochemical data. The tumour types represented were astrocytoma WHO I (n = 7), astrocytoma WHO II (n = 6), astrocytoma WHO III (n = 14), glioblastoma WHO IV (n = 8), oligodendroglioma WHO II (n = 5), ependymoma WHO II (n = 5), choroid plexus papilloma WHO I (n = 5), pineoblastoma WHO IV (n = 5), medulloblastoma WHO IV (n = 5), neurinoma WHO I (n = 5), meningioma WHO I and WHO III (n = 75) and pituitary adenoma WHO I (n = 5). Only choroid plexus papillomas (5/5) and meningiomas showed E-cadherin expression. In benign meningiomas (n = 45; 100%), positive E-cadherin immunoreactivity was found regardless of the histomorphological subtype. E-Cadherin was also expressed in 21 WHO I meningiomas (100%) invading dura, bone, brain, and muscle. In contrast, E-cadherin was absent from the majority of morphologically malignant meningiomas (6/9, 66.6%). In addition, in recurrent meningiomas (n = 9), E-cadherin expression in the recurrent tumours was identical to that in the primary neoplasm except in cases with malignant progression, where the malignant recurrent tumour was E-cadherin negative. In 2 cases of metastasizing meningiomas, no E-cadherin immunoreactivity was found in the primary tumours or their metastases.