Secretagogin expression in tumours of the human brain and its coverings

Secretagogin is a recently described calcium-binding protein, which is expressed in some neurons of the human brain. In this study we systematically investigated secretagogin expression in 245 tumours of the human brain and its coverings using immunohistochemistry. We found focal or widespread secretagogin expression in tumour cells in 1/18 oligoastrocytomas, 1/19 oligodendrogliomas, 2/20 anaplastic oligodendrogliomas, 2/9 ependymomas, 2/11 anaplastic ependymomas, 2/10 glioblastomas, 3/11 gangliogliomas and 1/2 anaplastic gangliogliomas, 10/10 central neurocytomas, 5/10 classic medulloblastomas, 4/5 desmoplastic medulloblastomas, 3/5 large cell/anaplastic medulloblastomas, 3/5 neuroblastomas, 3/10 meningiomas, 2/10 haemangioblastomas, and 13/19 pituitary adenomas. Further, we observed secretagogin expression in endothelial cells in 5/10 meningiomas, 2/5 haemangiopericytomas, and 2/10 haemangioblastomas. We detected no secretagogin expression in fibrillary astrocytoma, pilocytic astrocytoma, DNT, pineocytoma, pineoblastoma, subependymal giant cell astrocytoma (SEGA), atypical teratoid/rhabdoid tumour (AT/RT), or primary central nervous system lymphoma (PCNSL). We conclude that secretagogin is differentially expressed in human neuronal, glial, and embryonal brain tumours, meningial neoplasms and pituitary adenomas. Our findings indicate that secretagogin is involved in the calcium metabolism of tumour cells and endothelial cells in a subset of neoplasms of the brain and its coverings. Anti-secretagogin immunohistochemistry does not seem to be helpful in most differential diagnostic situations in surgical neuropathology.