Supplementary Data from Differentiation Therapy Exerts Antitumor Effects on Stem-like Glioma Cells

Abstract Purpose: Stem-like tumor cells comprise a highly tumorigenic and therapy-resistant tumor subpopulation, which is believed to substantially influence tumor initiation and therapy resistance in glioma. Currently, therapeutic, drug-induced differentiation is considered as a promising approach to eradicate this tumor-driving cell population; retinoic acid is well known as a potent modulator of differentiation and proliferation in normal stem cells. In glioma, knowledge about the efficacy of retinoic acid–induced differentiation to target the stem-like tumor cell pool could have therapeutic implications. Experimental Design: Stem-like glioma cells (SLGC) were differentiated with all-trans retinoic acid–containing medium to study the effect of differentiation on angiogenesis, invasive growth, as well as radioresistance and chemoresistance of SLGCs. In vivo effects were studied using live microscopy in a cranial window model. Results: Our data suggest that in vitro differentiation of SLGCs induces therapy-sensitizing effects, impairs the secretion of angiogenic cytokines, and disrupts SLGCs motility. Further, ex vivo differentiation reduces tumorigenicity of SLGCs. Finally, we show that all-trans retinoic acid treatment alone can induce antitumor effects in vivo. Conclusions: Altogether, these results highlight the potential of differentiation treatment to target the stem-like cell population in glioblastoma. Clin Cancer Res; 16(10); 2715–28. ©2010 AACR.

Author's A of Neurosu Pathology 5Molecular 7Tumor Im Germany; Huazhong Note: Supp Research O

PURPOSE:The CD133 antigen has been identified as a putative stem cell marker in normal and malignant brain tissues. In gliomas, it is used to enrich a subpopulation of highly tumorigenic cancer cells. According to the cancer stem cell hypothesis, CD133-positive cells determine long-term tumor growth and, therefore, are suspected to influence clinical outcome. To date, a correlation between CD133 expression in primary tumor tissues and patients' prognosis has not been reported.EXPERIMENTAL DESIGN:To address this question, we analyzed the expression of the CD133 stem cell antigen in a series of 95 gliomas of various grade and histology by immunohistochemistry on cryostat sections. Staining data were correlated with patient outcome.RESULTS:By multivariate survival analysis, we found that both the proportion of CD133-positive cells and their topological organization in clusters were significant (P < 0.001) prognostic factors for adverse progression-free survival and overall survival independent of tumor grade, extent of resection, or patient age. Furthermore, proportion of CD133-positive cells was an independent risk factor for tumor regrowth and time to malignant progression in WHO grade 2 and 3 tumors.CONCLUSIONS:These findings constitute the first conclusive evidence that CD133 stem cell antigen expression correlates with patient survival in gliomas, lending support to the current cancer stem cell hypothesis.