Caspase-3-like Death Protease is Inhibited by Interleukin-7

Highly metastatic mouse T-lymphoma CS21 cells can grow in vitro when cocultured with CA12 lymph node stromal cells, but they undergo apoptotic cell death when separated from CA12 stromal cells. It has been found that cysteine and interleukin-7(IL-7) as antiapoptotic soluble factors that produced by CA12 stromal cells. In this study, we report that an ICE family protease is activated in CS21 cells when separated from CA12 stromal cells and cultured alone. Enzyme purification using an avidin affinity column revealed that the involved cysteine protease possessed caspase3-like death protease activity. In addition, when IL-7 was added to CS21 cell culture, the protease activity could not be detected during partial purification of the enzyme. Taken together, these results strongly suggest that the caspase3-like protease activation is suppressed by IL-7 as an antiapoptotic factor that leads to abrogation of apoptosis execution.