Transcriptional expression of survivin and its splice variants in brain tumors in humans

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Abstract
Object. Survivin, one of the apoptosis inhibitor proteins, has been detected in most cancers in humans. In addition, two splice variants (survivin-2B and survivin-ΔEx3) have been identified. The authors investigated the transcription levels of survivin messenger (m)RNA and its splice variants in nine tumor cell lines, including gliomas, and in 25 brain tumor samples, by performing quantitative reverse transcription-polymerase chain reaction. The correlation between transcript expression levels and pathological findings were also analyzed. Methods. Transcription levels were measured using primer pairs specific for survivin and either of its splice variants and were normalized to the glyceraldehyde 6-phosphate dehydrogenase. Among the tumor cell lines tested, glioblastoma cell lines showed the highest levels of survivin expression. Among brain tumor samples studied, survivin was preferentially expressed in malignant brain tumors and gliomas. The relative expression level of survivin-ΔEx3/survivin was significantly higher in malignant than in benign brain tumor samples. Expression patterns were dominant for survivin-ΔEx3 in malignant brain tumors and dominant for survivin-2B in benign ones. A significant linear correlation between survivin mRNA expression and MIB-1 labeling index was demonstrated in all brain tumor samples. Conclusions. The authors' results indicate that quantifying the levels of survivin and its splice variants is useful for the prediction of the cell biological malignancy of gliomas, independent of their pathological features.