Immunohistochemical analysis of GFAP-δ and nestin in cerebral astrocytomas.

GFAP-δ, the delta isoform of the glial fibrillary acidic protein, is particularly expressed in the subventricular zone (SVZ) of the brain. GFAP-δ positive cells in the SVZ co-express the neural stem cells (NSCs) marker nestin. According to the theory of glioma oncogenesis, transformation of a cell population with stem features which resides in the SVZ could be the origin of astrocytomas. Moreover, it is known that cancer stem cells promote tumor invasion in cerebral astrocytomas. Therefore, we investigated the immunostaining of GFAP-δ and nestin in cerebral astrocytomas and evaluated the correlation between the positive cell ratio of these markers and the neuroimaging features associated with tumor invasion in forty-four cases of grade II, III and IV cerebral astrocytomas (World Health Organization's classification). Tissue samples were obtained by stereotactic biopsies in all cases. According to the preoperative neuroimaging criteria, tumors were categorized into highly invasive and low invasive. Most of the low-grade and high-grade astrocytomas express GFAP-δ and nestin. The positive cell ratio of GFAP-δ and the positive cell ratio of nestin were statistically significantly higher in highly invasive tumors compared with low-invasive tumors (p < 0.05). Altogether, these results suggest that GFAP-δ and nestin could be clinically relevant markers associated with tumor invasiveness in cerebral astrocytomas.