Title:Combination of Ethacrynic Acid and ATRA Triggers Differentiation and/or Apoptosis
of Acute Myeloid Leukemia Cells through ROS
Volume: 24
Issue: 6
Author(s): Lu Li, Hui-Min Xi, Hao Lu and Xun Cai*
Affiliation:
- State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Shanghai Institute of
Hematology, Ruijin Hospital, Shanghai Jiao Tong University, School of Medicine, No. 197 Ruijin Road II, Shanghai, 200025, China
Keywords:
All-trans retinoic acid, ethacrynic acid, acute myeloid leukemia, apoptosis, reactive oxygen species, differentiation.
Abstract:
Background and objective: All-trans retinoic acid (ATRA), an effective differentiation inducer, has
been applied clinically to treat acute promyelocytic leukemia (APL). Unfortunately, it is not as potent in other
kinds of acute myeloid leukemia (AML). Ethacrynic acid (EA), a classical powerful diuretic, can increase reactive
oxygen species (ROS) contents, which can assist ATRA in inducing differentiation in AML cells. Here, we
investigated the effect of EA combined with ATRA (EA+RA) on some AML cells except APL.
Methods: Apoptosis and differentiation were determined by morphology, cell viability, Annexin-V assay and
CD11c expression. Western blot analysis and the detection of ROS and mitochondrial transmembrane potentials
(MMP) were used to investigate the mechanisms.
Results: AML cells exhibited differentiation and/or apoptosis after EA+RA treatment. EA+RA increased the
intracellular ROS contents. EA+RA-induced apoptosis was accompanied by MMP attenuation and caspase-3/7
activation. EA+RA-induced differentiation was along with MEK/ERK and Akt activation and increased expression
of PU.1, CCAAT/enhancer-binding protein β (C/EBPβ) and C/EBPε. N-acetyl-L-cysteine (NAC), an antioxidant,
thoroughly reduced EA+RA-increased ROS, and also inhibited MMP attenuation, the activation of caspase-
3/7, MEK/ERK and Akt pathways, the elevation of PU.1 and C/EBPs, and apoptosis and differentiation. However,
MEK or PI3K specific inhibitors only suppressed EA+RA-triggered differentiation and the elevation of PU.1
and C/EBPs, but not ROS levels.
Conclusion: EA+RA induced cell apoptosis through ROS dependent MMP attenuation and caspase 3/7 activation
while inducing differentiation by ROS-MEK/ERK-PU.1/C/EBPs and ROS-Akt-PU.1/C/EBPs pathways. In summary,
it may provide innovative ATRA-based combination therapy strategies for AML patients via ROS.