TY - JOUR
T1 - Synergistic induction of mitochondrial damage and apoptosis in human leukemia cells by flavopiridol and the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA)
AU - Almenara, J.
AU - Rosato, R.
AU - Grant, S.
N1 - Funding Information:
This work was supported by awards CA 63753 and CA 83705 from the NIH, and award 6630–01 from the Leukemia and Lymphoma Society of America.
PY - 2002
Y1 - 2002
N2 - Interactions between the histone deacetylase inhibitor SAHA (suberoylanilide hydroxamic acid) and the cyclin-dependent kinase (CDK) inhibitor flavopiridol (FP) were examined in human leukemia cells. Simultaneous exposure (24 h) of myelomonocytic leukemia cells (U937) to SAHA (1 μM) and FP (100 nm), which were minimally toxic alone (1.5±0.5% and 16.3±0.5% apoptosis respectively), produced a dramatic increase in cell death (ie 63.2±1.9% apoptotic), reflected by morphology, procaspase-3 and -8 cleavage, Bid activation, diminished ΔΨm, and enhanced cytochrome c release. FP blocked SAHA-mediated up-regulation of p21CIP1 and CD11b expression, while inducing caspase-dependent Bc1-2 and pRb cleavage. Similar interactions were observed in HL-60 and Jurkat leukemia cells. Enhanced apoptosis in SAHA/FP-treated cells was accompanied by a marked reduction in clonogenic surivival. Ectopic expression of either dominant-negative caspase-8 (C8-DN) or CrmA partially attenuated SAHA/FP-mediated apoptosis (eg 45±1.5% and 38.2±2.0% apoptotic vs 78±1.5% in controls) and Bid cleavage. SAHA/FP induced-apoptosis was unaffected by the free radical scavenger L-N-acetyl cysteine or the PKC inhibitor GFX. Finally, ectopic Bcl-2 expression marginally attenuated SAHA/FP-related apoptosis/cytochrome c release, and failed to restore clonogenicity in cells exposed to these agents. Together, these findings indicate that SAHA and FP interact synergistically to induce mitochondrial damage and apoptosis in human leukemia cells, and suggest that this process may also involve engagement of the caspase-8-dependent apoptotic cascade.
AB - Interactions between the histone deacetylase inhibitor SAHA (suberoylanilide hydroxamic acid) and the cyclin-dependent kinase (CDK) inhibitor flavopiridol (FP) were examined in human leukemia cells. Simultaneous exposure (24 h) of myelomonocytic leukemia cells (U937) to SAHA (1 μM) and FP (100 nm), which were minimally toxic alone (1.5±0.5% and 16.3±0.5% apoptosis respectively), produced a dramatic increase in cell death (ie 63.2±1.9% apoptotic), reflected by morphology, procaspase-3 and -8 cleavage, Bid activation, diminished ΔΨm, and enhanced cytochrome c release. FP blocked SAHA-mediated up-regulation of p21CIP1 and CD11b expression, while inducing caspase-dependent Bc1-2 and pRb cleavage. Similar interactions were observed in HL-60 and Jurkat leukemia cells. Enhanced apoptosis in SAHA/FP-treated cells was accompanied by a marked reduction in clonogenic surivival. Ectopic expression of either dominant-negative caspase-8 (C8-DN) or CrmA partially attenuated SAHA/FP-mediated apoptosis (eg 45±1.5% and 38.2±2.0% apoptotic vs 78±1.5% in controls) and Bid cleavage. SAHA/FP induced-apoptosis was unaffected by the free radical scavenger L-N-acetyl cysteine or the PKC inhibitor GFX. Finally, ectopic Bcl-2 expression marginally attenuated SAHA/FP-related apoptosis/cytochrome c release, and failed to restore clonogenicity in cells exposed to these agents. Together, these findings indicate that SAHA and FP interact synergistically to induce mitochondrial damage and apoptosis in human leukemia cells, and suggest that this process may also involve engagement of the caspase-8-dependent apoptotic cascade.
KW - Apoptosis
KW - Cytochrome c
KW - Flavopiridol
KW - Histone deacetylase inhibitor
KW - Leukemia
KW - SAHA
UR - http://www.scopus.com/inward/record.url?scp=0036050151&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0036050151&partnerID=8YFLogxK
U2 - 10.1038/sj.leu.2402535
DO - 10.1038/sj.leu.2402535
M3 - Article
C2 - 12094258
AN - SCOPUS:0036050151
SN - 0887-6924
VL - 16
SP - 1331
EP - 1343
JO - Leukemia
JF - Leukemia
IS - 7
ER -