Cathepsin inhibition induces apoptotic death in human leukemia and lymphoma cells

We examined the effects of cathepsin inhibitor 1 (CATI-1), a selective inhi bitor of cysteine cathepsins, on human leukemia and lymphoma cells. CATI-1 induced apoptosis in all 12 cell lines tested. Apoptosis of CATI-1-treated leukemia/lymphoma cells was caspase-independent, p53-independent, BAX-indep endent as well as MAP kinase-independent. Our findings provide unprecedente d experimental evidence that cathepsins play a pivotal role for the surviva l of human leukemia/lymphoma cells. Therefore, cathepsin inhibitors may pro vide the basis for new treatment programs against leukemia and lymphoma.