Targeting mitotic exit for cancer treatment.

Several chemotherapeutic drugs interfere with assembly of the mitotic spindle of cancer cells, leading to mitotic arrest, mediated by the spindle assembly checkpoint (SAC). However, cancer cells may be SAC-deficient and survive such treatment, due to mitotic slippage. Sensing of defective spindle assembly by the SAC, causes inhibition of the anaphase-promoting complex or cyclosome (APC/C), and blocks mitotic exit, by stabilizing APC/C substrates, such as cyclin B. Mitotic slippage may occur due to residual APC/C activity and slow cyclin B degradation. Recent preclinical data suggests that targeting mitotic exit by blocking APC/C activity is a much more efficient therapeutic approach than disturbing mitotic spindle assembly.