Icariside II Induces Apoptosis in U937 Acute Myeloid Leukemia Cells: Role of Inactivation of STAT3-Related Signaling
et al. (2012) Icariside II Induces Apoptosis in U937 Acute Myeloid Leukemia Cells: Role of Inactivation of
STAT3-Related Signaling. PLoS ONE 7(4): e28706. doi:10.1371/journal.pone.0028706
Icariside II Induces Apoptosis in U937 Acute Myeloid Leukemia Cells: Role of Inactivation of STAT3-Related Signaling
Sang-Hun Kang 0
Soo-Jin Jeong 0
Sun-Hee Kim 0
Ji-Hyun Kim 0
Ji Hoon Jung 0
Wonil Koh 0
Jung Hyo Kim 0
Dae Keun Kim 0
Chang-Yan Chen 0
Sung-Hoon Kim 0
Kevin D. Bunting, Emory University, United States of America
0 1 College of Oriental Medicine, Kyung Hee University , Seoul , South Korea , 2 Basic Herbal Research Group, Korea Institute of Oriental Medicine , Daejeon , South Korea , 3 Chosun Nursing College , Kwangju , South Korea , 4 College of Pharmacy, Woosuk University , Wanju , South Korea , 5 Beth Israel Deaconess Medical Center, Harvard Medical School , Boston, Massachusetts , United States of America
Background: The aim of this study is to determine anti-cancer effect of Icariside II purified from the root of Epimedium koreanum Nakai on human acute myeloid leukemia (AML) cell line U937. Methodology/Principal Findings: Icariside II blocked the growth U937 cells in a dose- and time-dependent manner. In this anti-proliferation process, this herb compound rendered the cells susceptible to apoptosis, manifested by enhanced accumulation of sub-G1 cell population and increased the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells. Icariside II was able to activate caspase-3 and cleaved poly (ADP-ribose) polymerase (PARP) in a timedependent manner. Concurrently, the anti-apoptotic proteins, such as bcl-xL and survivin in U937 cells, were downregulated by Icariside II. In addition, Icariside II could inhibit STAT3 phosphorylation and function and subsequently suppress the activation of Janus activated kinase 2 (JAK2), the upstream activators of STAT3, in a dose- and time-dependent manner. Icariside II also enhanced the expression of protein tyrosine phosphatase (PTP) SH2 domain-containing phosphatase (SHP)1, and the addition of sodium pervanadate (a PTP inhibitor) prevented Icariside II-induced apoptosis as well as STAT3 inactivation in STAT3 positive U937 cells. Furthermore, silencing SHP-1 using its specific siRNA significantly blocked STAT3 inactivation and apoptosis induced by Icariside II in U937 cells. Conclusions/Significance: Our results demonstrated that via targeting STAT3-related signaling, Icariside II sensitizes U937 cells to apoptosis and perhaps serves as a potent chemotherapeutic agent for AML.
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Funding: This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MEST) (No.
20110063466). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
. These authors contributed equally to this work.
Icariside II, a flavonoid compound, is derived from the stems and
leaves of Epimedium koreanum that has been traditionally utilized for
neurasthenia, amnesia and impotence in Oriental medicine [1,2].
The other compounds from E. koreanum exerted various biological
activities. For instance, icariin could stimulate angiogenesis by
activating the extracellular signal-related kinase (ERK) and
phosphatidylinositol 3-kinase (PI3K)/AKT/endothelial nitric oxide
synthase (eNOS)-dependent signal pathways in human endothelial
cells [3]. Also, ikarisoside A inhibited osteoclatogenic differentiation
via c-Jun N-terminal kinase (JNK) and nuclear factor kappa B
(NFkB) in RAW 264.7 cells [4]. We and others recently reported that
Icariside II appeared to possess anti-cancer activity against multiple
myeloma [5], prostate cancer [6] and osteosarcoma cells [7].
Acute myeloid leukemia (AML) is an aggressive malignancy
characterized by the rapid growth of abnormal white blood cells
(WBCs). AML is primarily treated by chemotherapy and rarely
applied by radiotherapy [8]. Although various chemotherapeutic
agents such as cytarabine, daunorubicin and idarubicin have been
developed for AML treatment, they can affect even normal cells to
cause unpleasant side effects such as anemia, bleeding and
infection. In recent studies, many groups have suggested the
potential of natural products as potent chemotherapeutic drugs for
AML to improve the therapeutic efficacy and lower the side
effects. For instance, wogonin, an active compound in Scutellaria
baicalensis, induced apoptosis by inhibiting telomerase activity in
HL-60 AML cells [9] and ajoene, a natural garlic compound, was
suggested as an anti-leukemic agent for AML therapy [10]. In
addition, corchorusin-D, a saikosaponin-like compound isolated
from Corchorus acutangulus, targeted mitochondrial apoptotic
pathways in HL-60 and U937 cells [11].
In the present study, the underlying anti-cancer mechanisms of
Icariside II in U937 AML cells wer (...truncated)