Survivin, Survivin-2B, and Survivin-deItaEx3 expression in medulloblastoma: biologic markers of tumour morphology and clinical outcome

Abstract

Survivin is an apoptotic inhibitor that is expressed at high levels in a variety of malignancies. Survivin has four known alternative splice forms (Survivin, Survivin-2B, Survivin-deltaEx3, and Survivin-3B), and the recent literature suggests that these splice variants have unique functions and subcellular localisation patterns. We evaluated 19 fresh-frozen paediatric medulloblastomas for the expression of three Survivin isoforms by quantitative PCR. Survivin was most highly expressed when compared with normal cerebellar tissue. We also investigated Survivin protein expression in 40 paraffin-embedded paediatric medulloblastoma tumours by immunohistochemistry. We found a statistically significant association between the percentage of Survivin-positive cells and histologic subtype, with the large-cell-anaplastic variant expressing Survivin at higher levels than the classic subtype. We also found a statistically significant relationship between the percent of Survivin-positive cells in the tumours and clinical outcome, with higher levels of Survivin correlating with a worse prognosis. In summary, our study demonstrates a role for Survivin as a marker of tumour morphology and clinical outcome in medulloblastoma. Survivin may be a promising future prognostic tool and potential biologic target in this malignancy.

Figure 1

Transcriptional expression of Survivin, Survivin-2B, and Survivin-deltaEx3 in 19 fresh-frozen medulloblastoma tumours using quantitative PCR. Fold expression compared to normal human cerebellum was calculated using the Relative Standard Curve Method (ABI). ‘A’=Alive, ‘D’=Dead, and ‘U’=Unknown outcome status.

Figure 2

Protein expression in Daoy cells and medulloblastoma tumours. Daoy cell line and two medulloblastoma tumour samples (#18 and #19) stained with the anti-Survivin antibody Novus-500-201 demonstrated three bands at the predicted molecular weights of Survivin, Survivin-2B, and Survivin-deltaEx3.

Figure 3

Kaplan–Meier curve of overall survival (OS) in 40 medulloblastoma patients, from our study population. The solid line represents OS, and the dotted lines represent the 95% confidence intervals.

Figure 4

Protein expression of Survivin in medulloblastoma tumours. Immunohistochemistry of (A) classic (× 140), (B) large-cell-anaplastic (× 270), (C) desmoplastic (× 70), and (D) extremely nodular medulloblastoma (× 70) using NB-500-201 antibody. Red staining indicates Survivin-positive cells. Note the specific nuclear localisation in all of the Survivin-positive cells. The arrow in (C) indicates the high percentage of staining in the internodular areas of a desmoplastic variant.

Figure 5

Box plot graphical representation of percent of cells staining positive with the NB-500-201 antibody in large-cell-anaplastic (LC) tumours vs classic tumours (C) (A), and in tumours of deceased patients vs those in living patients (B). The thick horizontal line within the box represents the mean value. The box itself represents the 25–75% range of data, and the vertical bars extending from the box represent the extreme values.