Zigang Dong

University of Minnesota Duluth, Duluth, Minnesota, United States

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Publications (258)1433.3 Total impact

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    ABSTRACT: Non-small-cell lung cancer (NSCLC) is associated with diverse genetic alterations including mutation of epidermal growth factor receptor (EGFR). Isoliquiritigenin (ILQ), a chalcone derivative, possesses anticancer activities. In the present study, we investigated the effects of ILQ on the growth of tyrosine kinase inhibitor (TKI)-sensitive and -resistant NSCLC cells and elucidated its underlying mechanisms. Treatment with ILQ inhibited growth and induced apoptosis in both TKI-sensitive and -resistant NSCLC cells. ILQ-induced apoptosis was associated with the cleavage of caspase-3 and poly-(ADP ribose)-polymerase, increased expression of Bim and reduced expression of Bcl-2. In vitro kinase assay results revealed that ILQ inhibited the catalytic activity of both wildtype and double mutant (L858R/T790M) EGFR. Treatment with ILQ inhibited the anchorage-independent growth of NIH3T3 cells stably transfected with either wildtype or double-mutant EGFR with or without EGF stimulation. ILQ also reduced the phosphorylation of Akt and ERK1/2 in both TKI-sensitive and -resistant NSCLC cells, and attenuated the kinase activity of Akt1 and ERK2 in vitro. ILQ directly interacted with both wildtype and double-mutant EGFR in an ATP-competitive manner. A docking model study showed that ILQ formed two hydrogen bonds (Glu762 and Met793) with wildtype EGFR and three hydrogen bonds (Lys745, Met793 and Asp855) with mutant EGFR. ILQ attenuated the xenograft tumor growth of H1975 cells, which was associated with decreased expression of Ki-67 and diminished phosphorylation of Akt and ERK1/2. Taken together, ILQ suppresses NSCLC cell growth by directly targeting wildtype or mutant EGFR.
    The Journal of biological chemistry. 11/2014;
  • Ann M Bode, Zigang Dong
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    ABSTRACT: Consuming plants for their presumed health benefits has occurred since early civilizations. Phytochemicals are found in various plants that are frequently included in the human diet and are generally thought to be safe for consumption because they are produced naturally. However, this is not always the case and in fact many natural compounds found in several commonly consumed plants are potential carcinogens or tumor promoters and should be avoided.
    Cancer prevention research (Philadelphia, Pa.). 10/2014;
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    ABSTRACT: 9-cis-UAB30 (UAB30) and Targretin are well-known retinoid X receptor (RXR) agonists. They were highly effective in decreasing the incidence of methylnitrosourea (MNU)-induced mammary cancers. However, whether the anti-mammary cancer effects of UAB30 or Targretin originate from the activation of RXR is unclear. In the present study, we hypothesized that UAB30 and Targretin not only affect RXR, but likely influence one or more off-target proteins. Virtual screening results suggest that Src is a potential target for UAB30 and Targretin that regulates extracellular matrix (ECM) molecules and cell motility and invasiveness. In vitro kinase assay data revealed that UAB30 or Targretin interacted with Src and attenuated its kinase activity. We found that UAB30 or Targretin substantially inhibited invasiveness and migration of MCF-7 and SK-BR-3 human breast cancer cells. We examined the effects of UAB30 and Targretin on the expression of matrix metalloproteinases (MMP)-9, which are known to play an essential role in tumor invasion. We show that activity and expression of MMP-9 were decreased by UAB30 or Targretin. Western blot data showed that UAB30 or Targretin decreased AKT and its substrate molecule p70s6k, which are downstream of Src in MCF-7 and SK-BR-3 cells. Moreover, knocking down the expression of Src effectively reduced the sensitivity of SK-BR-3 cells to the inhibitory effects of UAB30 and Targretin on invasiveness. Taken together, our results demonstrate that UAB30 and Targretin each inhibit invasion and migration by targeting Src in human breast cancer cells. © 2014 Wiley Periodicals, Inc.
    Molecular Carcinogenesis 10/2014; · 4.27 Impact Factor
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    ABSTRACT: Although specific compounds found in some East Asian traditional medicines have been shown to exhibit bioactive properties, their molecular mechanisms of action remain elusive. The bark of the Alnus species has been used for the treatment of various pathological conditions including hemorrhage, alcoholism, fever, diarrhea, skin diseases, inflammation, and cancer in East Asia for centuries. In this study, we show that hirsutenone, a bioactive compound in Alnus japonica, exhibits anti-cancer effects against prostate cancer through a direct physical inhibition of Akt1/2. Hirsutenone suppressed anchorage-dependent and independent cell growth of PC3 and LNCaP human prostate cancer cells. Annexin V and Propidium iodide (PI) staining results demonstrated that hirsutenone strongly induces apoptotic cell death in both PC3 and LNCaP cells. Furthermore, treatment of hirsutenone attenuated phosphorylation of mammalian target of rapamycin (mTOR), a downstream substrate of Akt, without affecting Akt phosphorylation. Kinase and pull-down assay results clearly show that hirsutenone inhibits Akt1 and 2 by direct binding in an adenosine triphosphate (ATP)-noncompetitive manner in vitro and ex vivo. Our results show that hirsutenone suppresses human prostate cancer by targeting Akt1 and 2 as a key component to explain for anti-cancer activity of Alnus species. © 2014 Wiley Periodicals, Inc.
    Molecular Carcinogenesis 09/2014; · 4.27 Impact Factor
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    ABSTRACT: Studies have shown that a major metabolite of the red ginseng ginsenoside Rb1, called 20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol (GPD), exhibits anticancer properties. However, the chemotherapeutic effects and molecular mechanisms behind GPD action in human melanoma have not been previously investigated. Here we report the anticancer activity of GPD and its mechanism of action in melanoma cells. GPD, but not its parent compound Rb1, inhibited melanoma cell proliferation in a dose-dependent manner. Further investigation revealed that GPD treatment achieved this inhibition through the induction of autophagy and apoptosis, while Rb1 failed to show significant effect at the same concentrations. The inhibitory effect of GPD appears to be mediated through the induction of AMPK and the subsequent attenuation of mTOR phosphorylation. In addition, GPD activated c-Jun by inducing JNK phosphorylation. Our findings suggest that GPD suppresses melanoma growth by inducing autophagic cell death and apoptosis via AMPK/JNK pathway activation. GPD therefore has the potential to be developed as a chemotherapeutic agent for the treatment of human melanoma.
    PLoS ONE 08/2014; 9(8):e104305. · 3.53 Impact Factor
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    ABSTRACT: Non-small cell lung cancer (NSCLC) is the most lethal cancer causing more than 150,000 deaths in the United States in 2013. The receptor tyrosine kinase inhibitors (TKIs), such as gefitinib, are not perfect clinical therapeutic agents for NSCLC treatment due to primary or acquired TKI resistance. Herein, 3,6,2',4',5'- pentahydroxyflavone (36245-PHF) was identified as a multiple kinase inhibitor for NSCLC treatment based on the computational screening of a natural products database. 36245-PHF was shown to inhibit PI3-K, Aurora A and B kinases and overcome gefitinib-resistant NSCLC growth. Our data clearly showed that 36245-PHF markedly inhibited anchorage-independent growth of gefitinib-resistant NSCLC cell lines, and exerted a substantial chemotherapeutic effect following oral administration in a gefitinib-resistant NSCLC xenograft model. The evidence from 3 different subsequent methodological approaches, in vitro, ex vivo and in vivo, all confirmed that 36245-PHF as a multiple protein kinase inhibitor. Overall, we identified 36245-PHF as a multiple protein kinase inhibitor and as a novel therapeutic agent to overcome gefitinib-resistant NSCLC growth, which could provide a new option for clinical NSCLC oral treatment.
    The Journal of biological chemistry. 08/2014;
  • Yan Li, Xiang Li, Weiya Ma, Zigang Dong
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    ABSTRACT: The epidermal growth factor receptor (EGFR) is aberrantly activated in various cancer cells and an important target for cancer treatment. Deep understanding of EGFR conformational changes between the active and inactive states is of pharmaceutical interest. Here we present a strategy combining multiply targeted molecular dynamics simulations, unbiased molecular dynamics simulations, and Bayesian clustering to investigate transition pathways during the activation/inactivation process of EGFR kinase domain. Two distinct pathways between the active and inactive forms are designed, explored, and compared. Based on Bayesian clustering and rough two-dimensional free energy surfaces, the energy-favorable pathway is recognized, though DFG-flip happens in both pathways. In addition, another pathway with different intermediate states appears in our simulations. Comparison of distinct pathways also indicates that disruption of the Lys745-Glu762 interaction is critically important in DFG-flip while movement of the A-loop significantly facilitates the conformational change. Our simulations yield new insights into EGFR conformational transitions. Moreover, our results verify that this approach is valid and efficient in sampling of protein conformational changes and comparison of distinct pathways.
    Journal of Chemical Theory and Computation 08/2014; 10(8):3503-3511. · 5.39 Impact Factor
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    ABSTRACT: Caffeic acid (3,4-dihydroxycinnamic acid) is a well-known phenolic phytochemical present in coffee and reportedly has anticancer activities. However, the underlying molecular mechanisms and targeted proteins involved in the suppression of carcinogenesis by caffeic acid are not fully understood. In this study, we report that caffeic acid significantly inhibits colony formation of human skin cancer cells and EGF-induced neoplastic transformation of HaCaT cells dose-dependently. Caffeic acid topically applied to dorsal mouse skin significantly suppressed tumor incidence and volume in a solar UV-induced skin carcinogenesis mouse model. A substantial reduction of phosphorylation in mitogen-activated protein kinase signaling was observed in mice treated with caffeic acid either before or after solar UV exposure. Caffeic acid directly interacted with ERK1/2 and inhibited ERK1/2 activities in vitro. Importantly, we resolved the co-crystal structure of ERK2 complexed with caffeic acid. Caffeic acid interacted directly with ERK2 at amino acid residues Q105, D106 and M108. Moreover, A431 cells expressing knockdown of ERK2 lost sensitivity to caffeic acid in a skin cancer xenograft mouse model. Taken together, our results suggest that caffeic acid exerts chemopreventive activity against solar UV-induced skin carcinogenesis by targeting ERK1 and 2.
    Cancer prevention research (Philadelphia, Pa.). 08/2014;
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    ABSTRACT: Solar ultraviolet (SUV) irradiation is a major factor in skin carcinogenesis, the most common form of cancer in the USA. The mitogen-activated protein (MAP) kinase cascades are activated by SUV irradiation. The 90 kDa ribosomal S6 kinase (RSK) and mitogen and stress activated protein kinase (MSK) proteins constitute a family of protein kinases that mediate signal transduction downstream of the MAP kinase cascades. In this study, phosphorylation of RSK and MSK1 was up-regulated in human squamous cell carcinoma (SCC) and solar UV-treated mouse skin. Kaempferol, a natural flavonol, found in tea, broccoli, grapes, apples and other plant sources, is known to have anticancer activity, but its mechanisms and direct target(s) in cancer chemoprevention are unclear. Kinase array results revealed that kaempferol inhibited RSK2 and MSK1. Pull-down assay results, ATP competition and in vitro kinase assay data revealed that kaempferol interacts with RSK2 and MSK1 at the ATP-binding pocket and inhibits their respective kinase activities. Mechanistic investigations showed that kaempferol suppresses RSK2 and MSK1 kinase activities to attenuate solar UV-induced phosphorylation of CREB and histone H3 in mouse skin cells. Kaempferol was a potent inhibitor of solar UV-induced mouse skin carcinogenesis. Further analysis showed that skin from the kaempferol-treated group exhibited a substantial reduction in solar UV-induced phosphorylation of cAMP response element-binding protein (CREB), c-Fos and histone H3. Overall, our results identify kaempferol as a safe and novel chemopreventive agent against solar UV-induced skin carcinogenesis that acts by targeting RSK2 and MSK1.
    Cancer prevention research (Philadelphia, Pa.). 07/2014;
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    ABSTRACT: Lung cancer is a leading cause of death worldwide and MET amplification is a major therapeutic limitation in acquired-resistance lung cancer. We hypothesized that butein, a phytochemical, can overcome gefitinib-induced resistance by targeting both EGFR and MET in non-small cell lung cancer (NSCLC). To investigate the ability of butein to target EGFR and MET, we used in silico docking, a library of natural compounds and kinase assays. The effects of butein on growth, induction of apoptosis and expression of EGFR/MET signaling targets were examined in HCC827 (gefitinib-sensitive) and HCC827GR (gefitinib-resistant) NSCLC cells. Results were confirmed in vivo by a HCC827 or HCC827GR cell xenograft mouse model, each treated with vehicle, butein or gefitinib. Butein inhibited phosphorylation and kinase activity of EGFR and MET as well as soft agar colony formation and decreased viability of HCC827 and HCC827GR cells. Butein increased apoptosis-related protein expression in these cells. Results were confirmed by co-treatment with inhibitors of EGFR/MET or double knock-down. Finally, xenograft study results showed that butein strongly suppressed HCC827 and HCC827GR tumor growth. Immunohistochemical data suggest that butein inhibited Ki-67 expression. These results indicate that butein has potent anticancer activity and targets both EGFR and MET in acquired-resistance NSCLC. © 2014 Wiley Periodicals, Inc.
    Molecular Carcinogenesis 06/2014; · 4.27 Impact Factor
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    ABSTRACT: Nearly a hundred years of scientific research has revealed a notable preference of cancer cells to utilize aerobic glycolysis rather than mitochondrial oxidative phosphorylation for glucose-dependent ATP production, which is thought to be the root of tumor formation and growth. Glycolysis is a complex biochemical process that is mediated by multiple glycolytic genes. Besides regulating glucose metabolism, these genes are also suggested to possess various other functions related to cancer, including roles in cancer development and promotion, inhibition of apoptosis, cell cycle progression, and tumor metastasis. This article highlights the biological functions of glycolytic genes beyond their role in regulation of glycolysis and discusses their clinical implications, especially in regard to the use of glycolytic genes as biomarkers for early detection of cancer or as targets for novel anticancer treatments.
    Journal of Molecular Medicine 06/2014; · 4.77 Impact Factor
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    ABSTRACT: For decades, skin cancer incidence has increased, mainly due to oncogenic signaling pathways activated by solar ultraviolet (UV) irradiation (i.e., sun exposure). Solar UV induces multiple signaling pathways that are critical in the development of skin cancer, and therefore the development of compounds capable of targeting multiple molecules for chemoprevention of skin carcinogenesis is urgently needed. Herein, we examined the chemopreventive effects and the molecular mechanism of HOEC, [(+)-2-(1-hydroxyl-4-oxocyclohexyl) ethyl caffeate], isolated from Incarvillea mairei var. grandiflora (Wehrhahn) Grierson. HOEC strongly inhibited neoplastic transformation of JB6 C14l cells without toxicity. PI3-K, ERK1/2 and p38 kinase activities were suppressed by direct binding with HOEC in vitro. Our in silico docking data showed that HOEC binds at the ATP-binding site of each kinase. The inhibition of solar UV-induced PI3-K, ERK1/2 and p38 kinase activities resulted in suppression of their downstream signaling pathways and AP-1 and NF-κB transactivation in JB6 cells. Furthermore, topical application of HOEC reduced skin cancer incidence and tumor volume in SKH-1 hairless mice chronically exposed to solar UV. In summary, our results show that HOEC exerts inhibitory effects on multiple kinase targets and their downstream pathways activated by solar UV in vitro and in vivo. These findings suggest that HOEC is as a potent chemopreventive compound against skin carcinogenesis caused by solar UV exposure.
    Cancer prevention research (Philadelphia, Pa.). 05/2014;
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    ABSTRACT: Various health effects have been attributed to the ginsenoside metabolite 20-O-β-D-glucopyranosyl-20(S)-protopanaxadiol (GPD); however, its effect on ultraviolet (UV)-induced matrix metalloproteinase (MMP)-1 expression and the mechanism underlying this effect are unknown. We examined the inhibitory effect of GPD on UV-induced MMP-1 expression and its mechanisms in human dermal fibroblasts (HDFs). GPD attenuated UV-induced MMP-1 expression in HDFs and suppressed the UV-induced phosphorylation of mammalian target of rapamycin (mTOR) and p70S6K without inhibiting the activity of phosphatidylinositol 3-kinase and Akt, which are well-known upstream kinases of mTOR. GPD augmented the phosphorylation of liver kinase B1 (LKB1) and adenosine monophosphate-activated protein kinase (AMPK), which are inhibitors of mTOR, to a greater extent than UV treatment alone. Similar to GPD, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosyl 5′-monophosphate (AICAR), an activator of AMPK, augmented UV-induced AMPK phosphorylation to a greater extent than UV treatment alone, resulting in the inhibition of MMP-1 expression. AICAR also decreased the phosphorylation of mTOR and p70S6K. However, compound C, an antagonist of AMPK, increased MMP-1 expression. In HDF cells with AMPK knock-down using shRNA, MMP-1 expression was increased. These results indicate that AMPK activation plays a key role in MMP-1 suppression. Additionally, the cAMP-dependent protein kinase (PKA) inhibitor, H-89, antagonized GPD-mediated MMP-1 suppression via the inhibition of LKB1. Our results suggest that the suppressive activity of GPD on UV-induced MMP-1 expression is due to the activation of AMPK as a downstream of the PKA-LKB1 pathway. J. Cell. Biochem. © 2014 Wiley Periodicals, Inc.
    Journal of Cellular Biochemistry 05/2014; · 3.06 Impact Factor
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    ABSTRACT: Nanog regulates human and mouse embryonic stem (ES) cell self-renewal activity. Activation of ERKs signaling negatively regulates ES cell self-renewal and induces differentiation, but the mechanisms are not understood. We found that ERK1 binds and phosphorylates Nanog. Activation of MEK/ERKs signaling and phosphorylation of Nanog inhibit Nanog transactivation, inducing ES cell differentiation. Conversely, suppression of MEK/ERKs signaling enhances Nanog transactivation to inhibit ES cell differentiation. We observed that phosphorylation of Nanog by ERK1 decreases Nanog stability through ubiquitination-mediated protein degradation. Further, we found that this phosphorylation induces binding of FBXW8 with Nanog to reduce Nanog protein stability. Overall, our results demonstrated that ERKs-mediated Nanog phosphorylation plays an important role in self-renewal of ES cells through FBXW8-mediated Nanog protein stability.
    Stem Cell Research 04/2014; 13(1):1-11. · 4.47 Impact Factor
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    ABSTRACT: Phosphatase and tensin homolog (PTEN) loss or mutation consistently activates the phosphatidylinositol 3-kinase (PI3-K)/Akt signaling pathway, which contributes to the progression and invasiveness of prostate cancer. Furthermore, the PTEN/PI3-K/Akt and Ras/MAPK pathways cooperate to promote the epithelial–mesenchymal transition (EMT) and metastasis initiated from prostate stem/progenitor cells. For these reasons, the PTEN/PI3-K/Akt pathway is considered as an attractive target for both chemoprevention and chemotherapy. Herein we report that eupafolin, a natural compound found in common sage, inhibited proliferation of prostate cancer cells. Protein content analysis indicated that phosphorylation of Akt and its downstream kinases was inhibited by eupafolin treatment. Pull-down assay and in vitro kinase assay results indicated that eupafolin could bind with PI3-K and attenuate its kinase activity. Eupafolin also exhibited tumor suppressive effects in vivo in an athymic nude mouse model. Overall, these results suggested that eupafolin exerts antitumor effects by targeting PI3-K. © 2014 Wiley Periodicals, Inc.
    Molecular Carcinogenesis 04/2014; · 4.27 Impact Factor
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    ABSTRACT: Curcumin, the yellow pigment of turmeric found in Southeast Indian food, is one of the most popular phytochemicals for cancer prevention. Numerous reports have demonstrated modulation of multiple cellular signaling pathways by curcumin and its molecular targets in various cancer cell lines. To identify a new molecular target of curcumin, we used shape screening and reverse docking to screen the protein data bank against curcumin. Cyclin dependent kinase 2 (CDK2), a major cell cycle protein, was identified as a potential molecular target of curcumin. Indeed, in vitro and ex vivo kinase assay data revealed a dramatic suppressive effect of curcumin on CDK2 kinase activity. Furthermore, curcumin induced G1 cell cycle arrest, which is regulated by CDK2 in HCT116 cells. Although the expression levels of CDK2 and its regulatory subunit, cyclin E, were not changed, the phosphorylation of Rb, a well-known CDK2 substrate, was reduced by curcumin. Because curcumin induced cell cycle arrest, we investigated the anti-proliferative effect of curcumin on HCT116 colon cancer cells. In this experiment, curcumin suppressed HCT116 cell proliferation effectively. To determine if CDK2 is a direct target of curcumin, CDK2 expression was knocked down in HCT116 cells. As expected, HCT116 sh-CDK2 cells exhibited G1 arrest and reduced proliferation. Because of the low levels of CDK2 in HCT116 sh-CDK2 cells, the effects of curcumin on G1 arrest and cell proliferation were not substantial relative to HCT116 sh-control cells. From these results, we identified CDK2 as a direct target of curcumin in colon cancer cells.
    Cancer Prevention Research 02/2014; · 4.89 Impact Factor
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    ABSTRACT: Maillard reaction products are known to have anti inflammatory property. Objective of this study was to assess anti-arthritis effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal and its action mechanisms. Lipopolysaccharide (LPS)-activated macrophage (RAW264.7) and synoviocytes were treated with (E)-2,4-bis(p-hydroxyphenyl)-2-butenal for in vitro assay. (E)-2,4-bis(p-hydroxyphenyl)-2-butenal (5 mg/kg) was also periorally administered for 30 days to collagen (50 μg/g) induced arthritic mice. Clinical score, histopathological exam, NO generation, iNOS and COX2 expression, and NF-κB/IKK and STAT3 activities were determined in cultured cell and joint tissues of mice. Binding of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal to STAT3 was evaluated by a Pull-down assay and its binding site was predicted using molecular docking study with Autodock VINA. (E)-2,4-bis(p-hydroxyphenyl)-2-butenal (2.5-10 μg/ml) inhibited LPS (1 μg/ml)-induced NO generation, iNOS and COX2 expression, and NF-κB/IKK and STAT3 activities in macrophage and synoviocytes. (E)-2,4-bis(p-hydroxyphenyl)-2-butenal suppressed the collagen induced arthritic responses through inhibition of the expression of iNOS and COX2, and NF-κB/IKK and STAT3 activities, and also reduced the extent of bone destruction and fibrosis in joint tissues. A Pull-down assay proved that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal interfere with the binding of ATP to STAT3. Subsequent docking study proposes that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal binds to the the DNA binding interface of STAT3 possibly causing ATP binding to STAT3 in an allosteric manner. (E)-2,4-bis(p-hydroxyphenyl)-2-butenal exerted its anti-inflammatory and anti-arthritic effects through inhibition of NF-κB/STAT3 pathway via direct binding to STAT3, and that it could be a useful agent for the treatment of arthritic disease.
    British Journal of Pharmacology 02/2014; · 5.07 Impact Factor
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    ABSTRACT: Deregulation of the phosphatidylinositol 3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR)-70kDa ribosomal protein S6 kinase 1 (p70(S6K)) pathway is commonly observed in many tumors. This pathway controls proliferation, survival, and translation, and its overactivation is associated with poor prognosis for tumor-associated survival. Current efforts focus on the development of novel inhibitors of this pathway. In a cell-based high-throughput screening assay of 15 272 pure natural compounds, we identified pomiferin triacetate as a potent stabilizer of the tumor suppressor programmed cell death 4 (Pdcd4). Mechanistically, pomiferin triacetate appeared as a general inhibitor of the PI3K-Akt-mTOR-p70(S6K) cascade. Interference with this pathway occurred downstream of Akt but upstream of p70(S6K). Specifically, mTOR kinase emerged as the molecular target of pomiferin triacetate, with similar activities against mTOR complexes 1 and 2. In an in vitro mTOR kinase assay pomiferin triacetate dose-dependently inhibited mTOR with an IC50 of 6.2 μM. Molecular docking studies supported the interaction of the inhibitor with the catalytic site of mTOR. Importantly, pomiferin triacetate appeared to be highly selective for mTOR compared to a panel of 17 lipid and 50 protein kinases tested. As a consequence of the mTOR inhibition, pomiferin triacetate efficiently attenuated translation. In summary, pomiferin triacetate emerged as a novel and highly specific mTOR inhibitor with strong translation inhibitory effects. Thus, it might be an interesting lead structure for the development of mTOR- and translation-targeted anti-tumor therapies.
    Biochemical pharmacology 02/2014; · 4.25 Impact Factor
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    ABSTRACT: Soy isoflavone is an attractive source of functional cosmetic materials with anti-wrinkle, whitening and skin hydration effects. After consumption, the majority of soy isoflavones are converted to their metabolites in the human gastrointestinal tract. To understand the physiological impact of soy isoflavone on the human body, it is necessary to evaluate and address the biological function of its metabolites. In this study, we investigated the effect of 6,7,4'-trihydroxyisoflavone (6,7,4'-THIF), a major metabolite of daidzein, against solar UV (sUV)-induced matrix metalloproteinases (MMPs) in normal human dermal fibroblasts. MMPs play a critical role in the degradation of collagen in skin, thereby accelerating the aging process of skin. The mitogen-activated protein/extracellular signal-regulated kinase (MEK)/extracellular signal-regulated kinase (ERK), mitogen-activated protein kinase (MKK)3/6/p38 and MKK4/c-Jun N-terminal kinases (JNK) signaling pathways are known to modulate MMP-1 function, and their activation by sUV was significantly reduced by 6,7,4'-THIF pretreatment. Our results also indicated that the enzyme activity of protein kinase C (PKC)α, an upstream regulator of MKKs signaling, is suppressed by 6,7,4'-THIF using the in vitro kinase assay. Furthermore, the direct interaction between 6,7,4'-THIF and endogenous PKCα was confirmed using the pull-down assay. Not only sUV-induced MMP-1 expression, but also sUV-induced signaling pathway activation were decreased in PKCα knockdown cells. Overall, we elucidated the inhibitory effect of 6,7,4'-THIF on sUV-induced MMPs and suggest PKCα as its direct molecular target.
    International Journal of Molecular Sciences 01/2014; 15(11):21419-32. · 2.46 Impact Factor
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    ABSTRACT: Naproxen ((S)-6-methoxy-α-methyl-2-naphthaleneacetic acid) is a potent nonsteroidal anti-inflammatory drug that inhibits both COX-1 and COX-2 and is widely used as an over-the-counter medication. Naproxen exhibits analgesic, anti-pyretic, and anti-inflammatory activities. Naproxen, as well as other NSAIDS, has been reported to be effective in the prevention of urinary bladder cancer in rodents. However, potential targets other than the COX isozymes have not been reported. We examined potential additional targets in urinary bladder cancer cells and in rat bladder cancers. Computer kinase profiling results suggested that phosphatidylinositol 3-kinase (PI3-K) is a potential target for naproxen. In vitro kinase assay data revealed that naproxen interacts with PI3-K and inhibits its kinase activity. Pull-down binding assay data confirmed that PI3-K directly binds with naproxen in vitro and ex vivo. Western blot data showed that naproxen decreased phosphorylation of Akt, and subsequently decreased Akt signaling in UM-UC-5 and UMUC-14 urinary bladder cancer cells. Furthermore, naproxen suppressed anchorage-independent cell growth and decreased cell viability by targeting PI3-K in both cell lines. Naproxen caused an accumulation of cells at the G1 phase mediated through CDK4, cyclin D1 and p21. Moreover, naproxen induced significant apoptosis, accompanied with increased levels of cleaved caspase 3, caspase 7, and poly (ADP-ribose) polymerase (PARP) in both cell types. Naproxen-induced cell death was mainly due to apoptosis in which a prominent down-regulation of Bcl-2 and up-regulation of Bax were involved. Naproxen also caused apoptosis and inhibited Akt phosphorylation in rat urinary bladder cancers induced by N-butyl-N-(4-hydroxybutyl)-nitrosamine (OH-BBN).
    Cancer Prevention Research 12/2013; · 4.89 Impact Factor

Publication Stats

6k Citations
1,433.30 Total Impact Points

Institutions

  • 1998–2014
    • University of Minnesota Duluth
      Duluth, Minnesota, United States
  • 2012–2013
    • Catholic University of Korea
      Sŏul, Seoul, South Korea
    • The Advanced Institutes of Convergence Technology
      Yeoncheon Gun, South Korea
    • Korea Research Institute of Bioscience and Biotechnology KRIBB
      • Chemical Biology Research Center
      Anzan, Gyeonggi Province, South Korea
  • 2008–2013
    • Seoul National University
      • Department of Agricultural Biotechnology
      Seoul, Seoul, South Korea
    • Russian Academy of Sciences
      • G.B. Elyakov Pacific Institute of Bioorganic Chemistry
      Moskva, Moscow, Russia
    • Arizona Research Center
      Phoenix, Arizona, United States
  • 2006–2013
    • Central South University
      • Cancer Research Institute
      Changsha, Hunan, China
    • Pacific Institute of Bioorganic Chemistry
      Wladiwostok, Primorskiy, Russia
  • 2011–2012
    • Guangdong Medical College
      Tung-kuan, Guangdong, China
  • 2010–2011
    • Konkuk University
      • Department of Bioscience and Technology
      Seoul, Seoul, South Korea
  • 1999–2011
    • The University of Arizona
      • • Department of Pharmacology and Toxicology
      • • Department of Radiation Oncology
      Tucson, AZ, United States
  • 2003
    • Kanazawa University
      • Department of Hospital Pharmacy
      Kanazawa, Ishikawa, Japan