Expression of BMI1 in pediatric gliomas. (A) Analysis of BMI1 mRNA in pediatric brain astrocytomas (AST), juvenile pilocytic astrocytoma (JPA), ependymoma (EPN) and glioblastoma (GBM) using qRT-PCR. The relative levels of BMI1 were normalized to an internal control GAPDH and expressed as a percentage (mean ± SD). Red dotted lines indicate the levels of normal adult cerebral tissues. (B) BMI1 mRNA expression in the 8 PDOX mouse models. The relative levels of xenograft tumors during serial sub-transplantations from passage I to V (xeno-I to xeno-V) as well as the original patient tumors (Pt tum) (if available) were quantitated with qRT-PCR. (C) Representative immunohistochemical staining showing the GBM xenograft models with low-medium (IC-3704GBM and IC-3752GBM) and high BMI1 protein expressions (arrows) (IC-1406GBM and IC-2305GBM). (D) Western hybridization showing the increased BMI1 protein expression in the 8 GBM xenograft mouse models using beta-actin as loading control. Note that BMI1 protein was not expressed in the normal adult cerebral tissue, and the relative levels of BMI1 protein in the 8 xenograft models appeared to be correlated with their relative mRNA expressions, particularly in those with high mRNA transcripts (1406, 2305, 1128, and 1227). (E) Immunofluorescent staining showing that BMI1 protein was expressed in FACS-purified CD133+ and CD133- xenograft cells derived from ICb-1227AA.