Role of survivin splice variants in pediatric acute precursor B lymphoblastic leukemia.

Background: Survivin, a member of the inhibitor of apoptosis protein (IAP) family is transiently expressed at low levels during normal hematopoesis but profoundly overexpressed in adult leukemia potentially contributing to leukemogenesis due to deregulated apoptosis and defective cell cycle control. Alternative splicing results in four different mRNA variants survivin, survivin2B, survivin-Delta Exon3 and survivin-3B, with distinct cellular localization patterns and anti-apoptotic potential. Due to co-localization of survivin and survivin-2B in the cytoplasm survivin-2B may permit interactive fine-tuning of survivin actions and moreover play an attenuating role in its anti-apoptotic function. Lack of survivin-213 is associated with disease progression of malignomas suggesting a differential role of these isolforms in tumorigenesis. Patients and methods: We therefore determined the expression of the functional survivin splice variants performing RT- and real-time PCR in a purely pediatric cohort of 20 patients suffering from precursor B-ALL (BCP-ALL). Results: Here, we demonstrate for the first time in pediatric patients with precursor B-ALL an association between lower survivin-2B expression and affiliation to the high risk group. Conclusion: The idea that survivin-2B may act as natural antagonist of survivin could potentially be used in novel approaches of anti-cancer treatment by influencing the proportional expression of the different splice variants.