Expression of Bub1 gene correlates with tumor proliferating activity in human gastric carcinomas

Bub1 plays an important role at the spindle assembly checkpoint to prevent cell cycle progression following spindle damage. We examined the expression of human Bub1 mRNA in 20 gastric carcinoma tissues and corresponding nonne oplastic mucosas by reverse transcriptase-polymerase chain reaction and ana lyzed the relation with proliferative activity monitored by the expression of proliferating cell nuclear antigen (PCNA) on Western blotting as well as Ki-67 labeling index by immunohistochemistry. Increased expression of Bub1 mRNA was detected in 8 (40%) of the gastric carcinomas in comparison with their nonneoplastic counterparts, while 4 (20%) expressed Bub1 at lower lev els. The expression of Bub1 mRNA was confirmed by in situ hybridization. Th e expression levels of Bub1 mRNA were well correlated with the levels of PC NA protein in 16 (80%) gastric carcinoma cases. The examination of Ki-67 la beling indices proved the close correlation between the expression levels o f Bub1 and proliferating activity, These findings suggest that mRNA express ion of human Bub1 gene is closely associated with the tumor-proliferating a ctivity. Since genetic alterations of human Bub1 rarely occur in gastrointe stinal cancers, the functional machinery of Bub1 to prevent cell cycle prog ression into anaphase might be well preserved in gastric carcinomas even wi th high proliferative activity. Copyright (C) 2001 S. Karger AG, Basel.