DETECTION OF DNA STRAND BREAKS ASSOCIATED WITH APOPTOSIS IN HUMAN BRAIN-TUMORS

Apoptosis occurs spontaneously in a wide variety of neoplasms. However , it is difficult to detect apoptotic cells in routine histological se ctions because the cells undergoing apoptosis die singly and are then rapidly phagocytosed. Since DNA fragmentation is an important hallmark of apoptosis, visualization of DNA strand breaks in tissue sections p rovides the means for readily identifying apoptotic cells in situ. We have applied an in situ DNA strand break staining procedure for the qu antitative estimation of apoptotic cells in surgical specimens of 62 d ifferent brain tumours. Positively stained apoptotic cells were observ ed in 25 (40.3%) cases and their percentage (apoptotic index) ranged f rom 0.1 to 8.9. Both fragmented and condensed nuclei of apoptotic cell s and apoptotic bodies were stained. In addition, we assessed the prol iferative activity of each specimen by immunostaining with the MIB-1 a ntibody (MIB-1 index) which detects the cell cycle phase-dependent Ki- 67 antigen. Brain tumours with higher MIB-1 indices showed a tendency to higher apoptotic indices. The results of this study indicate that a poptosis occurs spontaneously in various brain tumours.