Nuclear survivin expression in mantle cell lymphoma is associated with cell proliferation and survival.

Survivin is a member of the inhibitor of apoptosis protein family that is expressed in G2/M phase. Survivin is overexpressed and associated with parameters of poor prognosis in different human tumors. The role of survivin in the pathogenesis of mantle cell lymphoma (MCL) was examined in a series of typical and blastoid tumors. Survivin was detected as a nuclear pattern in a variable number of tumor cells. Mitotic figures were always positive with a strong delineation of the chromosomes. Western blot analysis confirmed the presence of survivin only in nuclear fractions. Protein expression detected by immunohistochemistry correlated with mRNA levels analyzed by quantitative real-time reverse transcription-polymerase chain reaction (P < 0.0001). Survivin expression levels were higher in blastoid MCL variants (P < 0.0001) and were associated with the proliferative activity (P = 0.001), but not with the ploidy status of the tumors. The number of apoptotic cells was independent of survivin or Ki-67 expression. Overall survival was significantly shorter in patients with high survivin expression. However, in a multivariate analysis, proliferative index was a better predictor of survival than survivin score. These findings indicate that survivin is commonly expressed in MCL with a nuclear and mitotic pattern. The expression levels are strongly associated with the proliferative activity of the tumors and the survival of the patients, suggesting a potential role in cell cycle regulation and tumor progression.