Survivin expression in correlation with apoptotic activity in canine lymphomas

Survivin regulates cell cycle and mitosis and has antiapoptotic properties. Because of its dual function survivin has been the subject of much research focusing on its role in tumorigenesis and the relationship between survivin expression and apoptotic and/or proliferative activity in many types of human tumor including non-Hodgkin's Lymphomas. Such studies have not been conducted in canine lymphomas. The aim of this study was to evaluate the expression of survivin in canine lymphomas of low (5/25) and high (20/25) grades in relation to apoptotic markers (apoptotic index and index of caspase-3). Survivin was found in all examined lymphomas. Most tumors (18/25) showed survivin expression in 10%-25% of positive cells. Only in single cases was lower (0-10% positive cells, 1/25) or higher (25%-50% and >50% positive cells, 5/25 and 1/25, respectively) survivin expression. No significant differences between mean values of either index of survivin or apoptotic index was found between low and high grade lymphomas. However, such a difference among lymphoma grades was shown regarding the caspase-3 index. No correlation between the survivin index and either the apoptotic index or caspase-3 index was found, irrespective of the method of quantification: in whole specimens or in areas of low and high survivin expression. Positive correlation was consistently noted only between both apoptotic markers. The results indicate that survivin is commonly expressed in canine lymphomas. It seems that survivin does not exhibit anti-apoptotic activity in canine lymphomas. Lack of correlation between survivin expression and apoptotic markers could indicate its potential role in cell cycle activation in lymphoma cells.