WT1 expression in normal and neoplastic cranial and peripheral nerves is independent of grade of malignancy

Wilms' tumor protein (WT1) expression is usually absent in normal glial cells of the CNS but is highly upregulated in brain tumor cells and its expression correlates with tumor grade. However, knowledge on WT1 expression in tumors of the peripheral nerve system (PNS) is limited. As WT1 antibodies not only serve as biomarker for cancerous tissue but also are considered for cancer immunotherapy, knowledge of WT1 expression in tumorous and normal peripheral nerve tissue is important for therapeutical purposes.

We analyze the immunohistochemical expression of WT1 in 101 samples consisting of 13 normal nerves, 10 neurofibromas, 69 schwannomas and 9 malignant peripheral nerve sheath tumors (MPNST). Tumor samples included 14 specimen from patients with a proven neurocutaneous disorder (neurofibromatosis type 1 and 2) and 3 cases of schwannomatosis. In 50 vestibular schwannomas tumor growth extension was correlated to WT1 expression.

WT1 expression is present in Schwann cells of the majority of normal human nerves (11/13). In peripheral nerve sheath tumors, cytoplasmic WT1 protein is expressed in the cytoplasm of the neoplastic cells in all tumors, including MPNST, neurofibromas and schwannomas. The WT1 expression is independent of tumor malignancy or tumor growth extension and is not associated with a neurocutaneous disorder.

WT1 expression in normal and neoplastic tissue differs in the peripheral and the central nervous system. These findings may point to a different functional role of WT1 in the PNS and the CNS.