Possible involvement of caspase‐7 in cell cycle progression at mitosis

Caspases are suggested to play essential roles not only in apoptotic but also in non‐apoptotic functions. However, the contribution of caspases to the cell cycle regulation is unclear. Here we found that caspases including caspase‐3, caspase‐7, caspase‐8 and caspase‐9 were activated during mitosis. Chemically synthesized caspase inhibitors delayed mitotic progression and induced accumulation of mitotic cells, which exhibited abnormal chromatin condensation and incomplete chromosome segregation. Furthermore, knockdown of caspase‐7 by using small interfering RNAs resulted in the inhibition of cell proliferation, but knockdown of other caspases did not show a significant effect on cell growth. The expression of short hairpin RNA directed against caspase‐7 induced the cell cycle arrest at mitosis, which was rescued by the re‐expression of caspase‐7 containing silent mutations at the target site for the short hairpin RNA. These results revealed that caspase‐7 has a novel role during cell cycle progression at mitosis.