Brain Tumor Stem Cell Markers

Abstract

Brain tumors display striking heterogeneity of cellular morphology and differentiation status. Recent studies have identified tumor subpopulations in several brain tumor types that self-renew and can propagate tumor formation in mice models. These cells, called tumor stem cells, are defined functionally but several markers are under investigation to identify brain tumor stem cells. Although no marker has proven absolutely informative for the identification of brain tumor stem cells, several markers show promise for either prospective enrichment of some populations of brain tumor stem cells or for their identification in immunohistologic studies. The use of stem cell markers must be approached with caution as the method of detection and context are essential in interpretation. Several studies have investigated the relationship between expression of stem cell markers and patient prognosis with variable findings. The information provided by tumor stem cell markers may depend on the subtypes of tumors generated from different tumor cells of origin or oncogenic stimuli. Future studies may refine the utility of stem cell markers to the study of cancer stem cells through the identification of improved or additional markers and/or new methodologies. It is imperative to realize that brain tumor stem cells remain defined through functional assays (self-renewal, multilineage differentiation, and tumor propagation) and the expression of any marker is not definitive for a tumor stem cell phenotype.