T. Kiso et al., L-2,5-dihydrophenylalanine, an inducer of cathepsin-dependent apoptosis inhuman promyelocytic leukemia cells (HL-60), J ANTIBIOT, 54(10), 2001, pp. 810-817
L-2,5-Dihydrophenylalanine (DHPA), a phenylalanine analogue, induced apopto
sis in human promyelocytic leukemia cells (HL-60). This apoptosis was demon
strated by morphological changes of the cells, such as fragmentation of nuc
lei and chromatin condensation, and by some evidence found in biochemical a
nalysis, such as DNA ladder and activation of caspase 3. The DHPA-induced a
poptosis was prevented by a pan-caspase inhibitor, Z-VAD-fmk, and a cystein
e protease inhibitor, E-64d, which inhibits calpains and cathepsin B and L.
A calpain inhibitor, Z-LL-H, did not affect this apoptosis. A cathepsin B
specific inhibitor, CA074-Me, prevented only chromatin condensation. Howeve
r, E-64d and a cathepsin L specific inhibitor, Z-FY(t-Bu)-dmk, protected th
e cells from both chromatin condensation and oligonucleosomal DNA fragmenta
tion. As proceeding to the apoptotic process, the activities of both cathep
sin B and L increased gradually. These results indicated that DHPA was an i
nducer of cathepsin-dependent apoptosis in HL-60 cells.