Analysis of Glioma Stem Cell Markers and Genomic Alterations in Primary and Recurrent Glioblastomas.
Christina L Appin, Matthew J Schniederjan, Erwin Van Meir, Gena M Mastrogianakis, Daniel J Brat. Emory University School of Medicine, Atlanta, GA
Background: Glioblastoma (GBM) is an aggressive primary CNS tumor, with a median survival of one year following standard therapy. Previous studies demonstrated an association between the glioma stem cell (GSC) compartment and biologic aggressiveness. Moreover, recurrent post-radiation GBMs are enriched for GSCs in animal models. Here we investigate whether stem cell markers are increased in recurrent human GBMs compared to the primary and also examine whether genetic alterations are associated with the expression of GSC markers.
Design: Primary and recurrent GBMs from 13 patients (29-67 yrs-old; 4F, 9M) were included. Paraffin-embedded slides were stained for CD133, Sox2, Nestin, c-Myc and p53. FISH was performed for EGFR status. Immunohistochemical (IHC) staining for p53 was ranked as positive or negative. Quantification of CD133, Sox2, Nestin and c-Myc staining involved counting positive cells in 10 HPFs (40x), with intensity graded on a scale of 0-4, and then calculating an H-score. IHC and FISH results were compared with clinical parameters (age, gender, time to tumor recurrence) and analyzed for correlations. A rank sum test and the t-test were used to determine statistical significance.
Results: No statistically significant difference was noted in CD133, Sox2, Nestin or c-Myc staining in primary and recurrent GBMs. Expression of p53 was noted in 6/12 primary GBMs (50%). EGFR was amplified in 5/13 (38%). GBMs with EGFR amplification trended toward a higher H-score for Sox2 (mean = 2.8) than non-amplified cases (mean = 2.2; p = 0.06). P53 expression was not associated with differential c-Myc, CD133, Sox2 or Nestin expression. GBMs with high c-Myc expression (H > 0.9) recurred more quickly (mean = 9.4 mos) than those with lower expression (mean = 20 mos). Large increases in c-Myc expression (>75%) were associated with short recurrence intervals (p = 0.06).
Conclusions: In human GBMs, tumor cells expressing c-Myc, CD133, Nestin and Sox2 are not substantially increased in tumor recurrences. However, primary GBMs with high c-Myc expression and tumors with the greatest change in c-Myc expression from primary to recurrence had the shortest recurrence intervals. An association was noted between EGFR amplification and SOX2 expression.
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 231, Tuesday Afternoon