Expression of nestin - a stem cell associated intermediate filament in human CNS tumours

Background & objectives: Nestin is an intermediate filament protein expressed in undifferentiated cells during the development of brain and is considered as a marker for neuroepithelial stem cells. Expression of this protein in various CNS tumour cells suggests the possibility of existence of tumour stem cell modulating the evolution. We carried out an immunohistochemical study to demonstrate the expression of nestin and its co-expression with neuronal and glial intermediate filament and correlate with the grade of malignancy. Methods: Formalin fixed, paraffin processed sections from two human foetuses, 16 brain tumours of both neuronal and glial lineage and two metastatic tumours were immunostained with polyclonal antibody to nestin. Serial sections from primary brain tumours were also stained with monoclonal antibody to neurofilament (NF) and glial fibrillary acidic protein (GFAP). Fluorescent double labeling was carried out on four cases using laser confocal microscopy, to document co-localization of nestin with other intermediate filaments in the tumour cells. Results: Nestin expression was observed along the paraventricular zone of human foetuses and in brain tumours of both glial and neuronal lineage, of both high and low grades of malignancy. In addition, mature dysplastic spinal motor neurons adjacent to tumour and cerebellar Purkinje cells also expressed nestin along with neurofilament. Interpretation & conclusion: Nestin expression was noted in both low and high grade brain tumours and dysplastic neurons and did not parallel the malignant grade of the tumour. The expression of nestin in tumour cells and dysplastic neurons suggests aberrant expression of antigenically primitive proteins in cells to facilitate remodelling of the cell and migration. More studies are needed to elucidate the concept.