Distinct expression of Survivin splice variants in breast carcinomas

Abstract

Survivin, a member of the inhibitor apoptosis family, is expressed in several human tumours, and its expression is regulated by p53. Recently, three alternative splice variants (Survivin-2B, Survivin-deltaEx3 and Survivin-3B), differing in their antiapoptotic properties, were identified. To date, little is known about the expression of all Survivin splice variants in breast cancer, particularly the recently identified Survivin-3B variant. In this study, we show that all Survivin transcripts were expressed in breast tumour cell lines and breast carcinomas, with a very weak expression detected in adjacent normal tissue. Frequency of proapoptotic Survivin-2B was significantly higher in small tumour size (p=0.026) and was inversely associated with axillary node positive carcinomas (p=0.004). In contrast, Survivin-3B was more frequent in high-grade carcinomas (p=0.004). Correlation with p53 status revealed that Survivin-3B was significantly more frequent in carcinomas with p53 gene mutation (p=0.036). After neoadjuvant chemotherapy, a significant reduction in the percentage of expressing Survivin (p=0.016) and Survivin-2B (p=0.027) was observed, while no change was found for Survivin-deltaEx3 and Survivin-3B variants. These results demonstrate for the first time that Survivin variants are differentially expressed in breast cancer according to tumour progression and treatment and suggest that Survivin-3B might act as an antiapoptotic factor in this lesion, with its expression regulated by p53.