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Lee HW, Choi JH, Seo D, Gavaachimed L, Choi J, Park S, Min NY, Lee DH, Bang HW, Ham SW, Kim JW, Lee SC, Rhee S, Seo SB, Lee KH. EGCG-induced selective death of cancer cells through autophagy-dependent regulation of the p62-mediated antioxidant survival pathway. Biochim Biophys Acta Mol Cell Res 2024; 1871:119659. [PMID: 38216089 DOI: 10.1016/j.bbamcr.2024.119659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/22/2023] [Accepted: 12/29/2023] [Indexed: 01/14/2024]
Abstract
The effects of EGCG on the selective death of cancer cells by modulating antioxidant pathways through autophagy were explored in various normal and cancer cells. EGCG positively regulated the p62-KEAP1-NRF2-HO-1 pathway in normal cells, while negatively regulating it in cancer cells, leading to selective apoptotic death of cancer cells. In EGCG-treated MRC5 cells (EGCG-MRC5), autophagic flux was blocked, which was accompanied by the formation of p62-positive aggregates. However, EGCG-treated HeLa cells (EGCG-HeLa) showed incomplete autophagic flux and no aggregate formation. The levels of P-ULK1 S556 and S758 increased in EGCG-MRC5 through AMPK-mTOR cooperative interaction. In contrast, EGCG treatment in HeLa cells led to AMPK-induced mTOR inactivation, resulting in abrogation of P-ULK1 S556 and S758 levels. AMPK knockout in EGCG-HeLa restored positive regulation of the p62-mediated pathway, which was accompanied by increased P-mTOR S2448 and P-ULK1 S758 levels. Knockdown of 67LR in EGCG-HeLa abolished AMPK activity but did not restore the p62-mediated pathway. Surprisingly, both AMPK knockout and 67LR knockdown in EGCG-HeLa markedly increased cell viability, despite differential regulation of the antioxidant enzyme HO-1. In conclusion, EGCG induces the selective death of cancer cells through the modulation of at least two autophagy-dependent and independent regulatory pathways: negative regulation involves the mTOR-ULK1 (S556 and S758)-p62-KEAP1-NRF2-HO-1 axis via AMPK activation, whereas positive regulation occurs through the 67LR-AMPK axis.
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Affiliation(s)
- Ho Woon Lee
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Jee-Hye Choi
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Dongbeom Seo
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Lkhagvasuren Gavaachimed
- Department of Science of Cultural Properties, Graduate School, Chung-Ang University, Seoul, Republic of Korea
| | - Jaesung Choi
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Sehwan Park
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Na Young Min
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Dong Ho Lee
- Da Vinci College of General Education, Chung-Ang University, Seoul, Republic of Korea
| | - Hyo-Weon Bang
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Seung Wook Ham
- Department of Chemistry, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Jung-Woong Kim
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Sung Chul Lee
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Sangmyung Rhee
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Sang-Beom Seo
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea
| | - Kwang-Ho Lee
- Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul, Republic of Korea; Department of Science of Cultural Properties, Graduate School, Chung-Ang University, Seoul, Republic of Korea.
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Oh J, Jang H, Koh HR, Ham SW. Transport Mechanism for Nuclear Localization of Irradiation-Activated EGFR Measured by Single-Molecule Pull-Down Assay. Biochemistry 2023; 62:971-975. [PMID: 36744831 DOI: 10.1021/acs.biochem.2c00623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nuclear transport of epidermal growth factor receptor (EGFR) is considered to be a key cause of radiation resistance in cancer therapy. Here, we showed that irradiation-activated EGFR binds to the nuclear transport protein karyopherin alpha (KPNA) rather than karyopherin subunit beta 1 (KPNB1), through a single-molecule pull-down assay, which allows measurement of the binding affinity by single proteins in cell lysate without an additional purification step. We also obtained kinetic parameters for the binding between the phosphorylated nuclear localization signal (NLS) peptide of EGFR (645RRRHIVRKRpTLRR657) and KPNA. This observation may help developing small molecules to modulate nuclear transport, which potentially reduces the radiation resistance during irradiation therapy.
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Affiliation(s)
- Jiwon Oh
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Haeun Jang
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Hye Ran Koh
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
| | - Seung Wook Ham
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Republic of Korea
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Park C, Oh J, Lee WM, Koh HR, Sohn UD, Ham SW, Oh K. Inhibition of NUPR1-Karyopherin β1 Binding Increases Anticancer Drug Sensitivity. Int J Mol Sci 2021; 22:ijms22062794. [PMID: 33801927 PMCID: PMC8000408 DOI: 10.3390/ijms22062794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/23/2021] [Accepted: 03/02/2021] [Indexed: 11/21/2022] Open
Abstract
Background: Nuclear protein-1 (NUPR1, also known as p8/Com-1) is a transcription factor involved in the regulation of cellular stress responses, including serum starvation and drug stimulation. Methods: We investigated the mechanism of NUPR1 nuclear translocation involving karyopherin β1 (KPNB1), using a single-molecule binding assay and confocal microscopy. The cellular effects associated with NUPR1–KPNB1 inhibition were investigated by gene expression profiling and cell cycle analysis. Results: The single-molecule binding assay revealed that KPNB1 bound to NUPR1 with a binding affinity of 0.75 nM and that this binding was blocked by the aminothiazole ATZ-502. Following doxorubicin-only treatment, NUPR1 was translocated to the nucleus in more than 90% and NUPR1 translocation was blocked by the ATZ-502 combination treatment in MDA-MB-231 with no change in NUPR1 expression, providing strong evidence that NUPR1 nuclear translocation was directly inhibited by the ATZ-502 treatment. Inhibition of KPNB1 and NUPR1 binding was associated with a synergistic anticancer effect (up to 19.6-fold) in various cancer cell lines. NUPR1-related genes were also downregulated following the doxorubicin–ATZ-502 combination treatment. Conclusion: Our current findings clearly demonstrate that NUPR1 translocation into the nucleus requires karyopherin β1 binding. Inhibition of the KPNB1 and NUPR1 interaction may constitute a new cancer therapeutic approach that can increase the drug efficacy while reducing the side effects.
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Affiliation(s)
- Chanhee Park
- Center for Metareceptome Research, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Korea; (C.P.); (W.M.L.); (U.D.S.)
- Institute of Gastroenterology, College of Medicine, Yonsei University, 50-1 Yonsei-ro, Seodaemun, Seoul 03772, Korea
| | - Jiwon Oh
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Korea; (J.O.); (H.R.K.)
| | - Won Mo Lee
- Center for Metareceptome Research, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Korea; (C.P.); (W.M.L.); (U.D.S.)
| | - Hye Ran Koh
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Korea; (J.O.); (H.R.K.)
| | - Uy Dong Sohn
- Center for Metareceptome Research, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Korea; (C.P.); (W.M.L.); (U.D.S.)
| | - Seung Wook Ham
- Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Korea; (J.O.); (H.R.K.)
- Correspondence: (S.W.H.); (K.O.)
| | - Kyungsoo Oh
- Center for Metareceptome Research, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Korea; (C.P.); (W.M.L.); (U.D.S.)
- Correspondence: (S.W.H.); (K.O.)
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Yu HH, Ham SW, Lee Y. HPLC and ToF‒SIMS Analyses of Toxicodendron vernicifluum Tree Sap Mixed with Other Natural Lacquers. Molecules 2021; 26:molecules26020434. [PMID: 33467697 PMCID: PMC7830298 DOI: 10.3390/molecules26020434] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 12/04/2022] Open
Abstract
Lacquer sap has been used by humans from antiquitywhen it was treated as a luxury item because of its desirable physical properties. In modern times, although access barriers are lower, lacquer is still considered to be rare and valuable. Thus, low quality, inexpensive Vietnamese and Myanmarese lacquers and cashew nutshell liquid are frequently added to the costly Toxicodendron vernicifluum lacquer sap from Korea, China, and Japan. However, these blended lacquers can diminish the quality of artisan works. The Toxicodendron vernicifluum lacquer saps mixed with other natural lacquers were characterized using time-of-flight secondary-ion mass spectrometry (ToF−SIMS) and high-performance liquid chromatography (HPLC). ToF-SIMS provided the chemical structure of the lacquer monomer, copolymerized dimers, trimers, etc. HPLC provided quantitative analysis of the components of a randomly mixed lacquer. These techniques can be used to control the quality of commercial lacquer sap for the Asian lacquer industry and the traditional conservation of ancient objects.
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Affiliation(s)
- Hye Hyun Yu
- Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 02792, Korea;
- Department of Chemistry, Chung-Ang University, Seoul 06974, Korea;
| | - Seung Wook Ham
- Department of Chemistry, Chung-Ang University, Seoul 06974, Korea;
| | - Yeonhee Lee
- Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 02792, Korea;
- Correspondence: ; Tel.: +82-2-958-5971; Fax: +82-2-958-5969
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Oh J, Yoon S, Ham SW. Determination of Binding Affinities Between
NF‐κB
and Importins Using
Single‐Molecule
Binding Assays. B KOREAN CHEM SOC 2020. [DOI: 10.1002/bkcs.12082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jiwon Oh
- Department of Chemistry Chung‐Ang University Seoul 06974 Republic of Korea
| | - Seungil Yoon
- Department of Chemistry Chung‐Ang University Seoul 06974 Republic of Korea
| | - Seung Wook Ham
- Department of Chemistry Chung‐Ang University Seoul 06974 Republic of Korea
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Park CH, Ham SW, Shin H, Oh KS. Abstract 5138: Inhibition of kPNB1 and NUPR1 binding increase the anti-cancer drug sensitivity. Cancer Res 2019. [DOI: 10.1158/1538-7445.am2019-5138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Karyopherin beta 1 (KPNB1, known as importin beta 1) is carrier protein, it is known as transporter of protein from cytoplasm to nucleus through nuclear pore complexes (NPCs) using KPNAs as an adapters. The nuclear protein-1 (NUPR1, known as p8/Com-1) is identified as a transcription factor and it is showed multifunctional mechanisms related to cellular stress response such as serum-starvation, oxidative stress and drug stimulation. In this study, we investigated protein-protein interaction between NUPR1 and KPNB1, it might be a new target for cancer therapy.For the evaluation of binding affinity between protein and inhibition effect by compound 1, we processed the single molecule binding assay. Cytotoxicity of combination treatment with doxorubicin and compound 1 were validated several cancer cell lines such as MDA-MB-231, PC-3, SK-OV-3, and SiHa. Gene expression patterns were analyzed RNA-Seq and validated with qRT-PCR and western-blotting. KPNB1 bind to NUPR1 as a high affinity compare to KPNB1 single treatment assay and there was no difference according to concentration of NUPR1. KPNB1 and NUPR1 protein-protein interaction was inhibited by compound 1 according to concentration of compound 1 showed 71%, 44%, and 31% of inhibition rate with 50nM, 10nM, 2.5nM of compound 1, respectively. In doxorubicin single treatment, NUPR1 move to nucleus more than 90% of cells compare to non-treated MDA-MB-231 cells. Otherwise, NUPR1 was exist both nucleus and cytoplasm more than 90% cells, which is indicate that translocation of NUPR1 to the nucleus was blocked by compound 1 treatment. And combination treatment showed synergistic effect of cytotoxicity in various cancer cells such as such as MDA-MB-231, SiHa, PC-3, and SK-OV-3 (1.4 ~ 6 fold). Additionally, NUPR1 related genes were showed change of gene expression in compound 1 combination compared to doxorubicin single treatment. In these results suggest that translocation mechanism of NUPR1 into nucleus bind to KPNB1 and this binding was inhibited by compound 1 which is new candidate drug combination method for cancer therapy.
Citation Format: Chan Hee Park, Seung Wook Ham, HyeKyoung Shin, Kyung Soo Oh. Inhibition of kPNB1 and NUPR1 binding increase the anti-cancer drug sensitivity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5138.
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Affiliation(s)
| | | | - HyeKyoung Shin
- 2Yonsei University College of Medicine, Seoul, Republic of Korea
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Ha S, Jeong J, Oh J, Rhee S, Ham SW. A Small Organic Molecule Blocks EGFR Transport into the Nucleus by the Nonclassical Pathway Resulting in Repression of Cancer Invasion. Chembiochem 2017; 19:131-135. [PMID: 29159913 DOI: 10.1002/cbic.201700489] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Indexed: 02/06/2023]
Abstract
In addition to the traditional epidermal growth factor receptor (EGFR) signaling pathways, nuclear EGFR has been shown to control multiple cellular functions, including cell proliferation and invasion. It has been reported that EGFR is transported into the nucleus after forming a complex with KPNA/KPNB1 or KPNB1. Herein, it is shown that EGFR can interact with both KP and KPNA, but EGF-activated EGFR mostly binds with KPNB1 through the pull-down assay. Also, a small organic molecule (1), an effective binder of KPNB1, inhibits the interaction between EGFR and KPNB1 in the nonclassical transport pathway, but not KPNA. Furthermore, treatment of cancer cells with 1 noticeably blocks the nuclear entry of EGFR, which results in significant suppression of invasion by lung cancer H1299 cells. These findings show that 1 is an effective inhibitor of EGFR/KPNB1 interactions in vitro, it may be used in cellular studies as a tool to determine the role of nuclear EGFR, and it is a drug candidate.
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Affiliation(s)
- Siyoung Ha
- Department of Chemistry, Chung-Ang University, 84 Heakseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jangho Jeong
- Department of Life Science, Chung-Ang University, 84 Heakseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jiwon Oh
- Department of Chemistry, Chung-Ang University, 84 Heakseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Sangmyung Rhee
- Department of Life Science, Chung-Ang University, 84 Heakseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Seung Wook Ham
- Department of Chemistry, Chung-Ang University, 84 Heakseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
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Ha S, Choi J, Min NY, Lee KH, Ham SW. Inhibition of Importin β1 With a 2-Aminothiazole Derivative Resulted in G 2/M Cell-cycle Arrest and Apoptosis. Anticancer Res 2017; 37:2373-2379. [PMID: 28476803 DOI: 10.21873/anticanres.11575] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/06/2017] [Accepted: 04/07/2017] [Indexed: 11/10/2022]
Abstract
BACKGROUND The design and synthesis of novel chemotherapeutic agents that can induce apoptosis and cell-cycle arrest has emerged as an attractive approach for the treatment of cancer, because they can limit possible nonspecific effects of compound treatment. Previous studies established that the expression of KPNB1 was increased in several cancer cells and transformed cell lines and inhibition of KPNB1 using siRNA significantly inhibited cervical tumour proliferation, but did not affect normal cervical epithelium. Recently, we reported that a KPNB1 inhibitor, the 2-aminothiazole derivative 1, possesses strong anti-proliferative effects against several cancer cells in the nanomolar concentration range. RESULTS Treatment with compound 1 interferes with cell-cycle progression in the G2/M phase, as detected by flow cytometry analysis and results in apoptosis by the intrinsic pathway. Fluorescence microscopic analysis of mitotic cells predominantly mitotic abnormal cells with monopolar spindles and treatment with compound 1 did not affect polymerization of microtubules. CONCLUSION Compound 1, as a KPNB1 inhibitor, might be a good target for future development of anticancer agents showing the activities of apoptosis and cell cycle arrest.
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Affiliation(s)
- Siyoung Ha
- Department of Chemistry, Chung-Ang University, Seoul, Republic of Korea
| | - Jaesung Choi
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Na Young Min
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Kwang-Ho Lee
- Department of Life Science, Chung-Ang University, Seoul, Republic of Korea
| | - Seung Wook Ham
- Department of Chemistry, Chung-Ang University, Seoul, Republic of Korea
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Ha S, Oh J, Kim YH, Ham SW. Determination of the binding site of 2-aminothiazole derivative with importin β1 by UV-crosslinking experiment. J Chromatogr B Analyt Technol Biomed Life Sci 2017; 1060:71-75. [PMID: 28600962 DOI: 10.1016/j.jchromb.2017.05.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/29/2017] [Accepted: 05/30/2017] [Indexed: 10/19/2022]
Abstract
Importin β1 (KPBN1) appears to be overexpressed in several cancer cells and siRNA-induced inhibition of KPNB1 shows significant inhibition of cancer cell proliferation, but do not affect normal cells. These results indicate that KPNB1 is a potential target and inhibition of KPNB1 can be used as a novel therapeutic approach for the treatment of cancer. Recently, we identified the aminothiazole derivative 1 as a KPNB1-targeted anticancer agent. Herein, we report that compound 1 binds strongly to KPNB1, in a pocket centered around serine-476, as shown by UV-crosslinking and tandem mass spectrometry experiments, and supported using a model derived from molecular docking.
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Affiliation(s)
- Siyoung Ha
- Department of Chemistry, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Jiwon Oh
- Department of Chemistry, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Yong-Hak Kim
- Department of Catholic, University of Daegu, School of Medicine, Daegu 705-718, Republic of Korea.
| | - Seung Wook Ham
- Department of Chemistry, Chung-Ang University, Seoul 06974, Republic of Korea.
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Ha S, Oh J, Jang JM, Kim DK, Ham SW. Synthesis and Biological Evaluation of 2-Aminothiazole Derivative Having Anticancer Activity as a KPNB1 Inhibitor. B KOREAN CHEM SOC 2016. [DOI: 10.1002/bkcs.10968] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Siyoung Ha
- Department of Chemistry; Chung-Ang University; Seoul 06974 Republic of Korea
| | - Jiwon Oh
- Department of Chemistry; Chung-Ang University; Seoul 06974 Republic of Korea
| | - Ji Min Jang
- College of Pharmacy; Chung-Ang University; Seoul 06974 Republic of Korea
| | - Dae Kyong Kim
- College of Pharmacy; Chung-Ang University; Seoul 06974 Republic of Korea
| | - Seung Wook Ham
- Department of Chemistry; Chung-Ang University; Seoul 06974 Republic of Korea
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11
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Kim YH, Ha S, Kim J, Ham SW. Identification of KPNB1 as a Cellular Target of Aminothiazole Derivatives with Anticancer Activity. ChemMedChem 2016; 11:1406-9. [PMID: 27241026 DOI: 10.1002/cmdc.201600159] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/11/2016] [Indexed: 11/07/2022]
Abstract
We found that aminothiazole derivative (E)-N-(5-benzylthiazol-2-yl)-3-(furan-2-yl)acrylamide (1) has strong anticancer activity, and undertook proteomics approaches to identify the target protein of compound 1, importin β1 (KPNB1). A competitive binding assay using fluorescein-labeled 1 showed that 1 has strong binding affinity for KPNB1 (Kd : ∼20 nm). Furthermore, through western blotting assays for KPNB1, KPNA2, EGFR, ErbB2, and STAT3, we confirmed that 1 has inhibitory effects on the importin pathway. KPBN1 appears to be overexpressed in several cancer cells, and siRNA-induced inhibition of KPNB1 shows significant inhibition of cancer cell proliferation, while leaving non-cancerous cells unaffected. Therefore, compound 1 is a promising new lead for the development of KPNB1-targeted anticancer agents. Fluorescein-labeled 1 could be a useful quantitative probe for the development of novel KPNB1 inhibitors.
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Affiliation(s)
- Yong-Hak Kim
- Department, Catholic University of Daegu School of Medicine, 3056-6 Daemyeong 4-dong, Nam-gu, Daegu, 705-718, Republic of Korea
| | - Siyoung Ha
- Department of Chemistry, Chung-Ang University, 221 Heakseok-dong, Dongjak-gu, Seoul, 156-756, Republic of Korea
| | - Jungwon Kim
- Department of Chemistry, Chung-Ang University, 221 Heakseok-dong, Dongjak-gu, Seoul, 156-756, Republic of Korea
| | - Seung Wook Ham
- Department of Chemistry, Chung-Ang University, 221 Heakseok-dong, Dongjak-gu, Seoul, 156-756, Republic of Korea.
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Ha S, Kim DY, Min BH, Ham SW. Mechanism of Action of Copper Ion on the Activity of Protein Tyrosine Phosphatase PTP1B and Its Toxicological Activity. B KOREAN CHEM SOC 2015. [DOI: 10.1002/bkcs.10376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Siyong Ha
- Department of Chemistry, College of Natural Science; Chung-Ang University; Seoul 156-756 Korea
| | - Da Young Kim
- Department of Chemistry, College of Natural Science; Chung-Ang University; Seoul 156-756 Korea
| | - Bum Hong Min
- Department of Chemistry, College of Natural Science; Chung-Ang University; Seoul 156-756 Korea
| | - Seung Wook Ham
- Department of Chemistry, College of Natural Science; Chung-Ang University; Seoul 156-756 Korea
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Ham SW, Choe JI. mPW1PW91-Calculated Structures, IR Spectra, and Frontier Orbitals of 1,2-Bridged Calix[4]aryl Picrate Complexed with Alkali Metal Ions. B KOREAN CHEM SOC 2015. [DOI: 10.1002/bkcs.10289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Seung Wook Ham
- Department of Chemistry; Chung-Ang University; Seoul 156-756 Korea
| | - Jong-In Choe
- Department of Chemistry; Chung-Ang University; Seoul 156-756 Korea
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Ham SW, Choe JI. mPW1PW91-Calculated Structures, IR Spectra, and Frontier Orbitals of Benzoylmethoxythiacalix[4]arene Complexed with Alkali Metal Ions. B KOREAN CHEM SOC 2015. [DOI: 10.1002/bkcs.10003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Seung Wook Ham
- Department of Chemistry; Chung-Ang University; Seoul 156-756 Korea
| | - Jong-In Choe
- Department of Chemistry; Chung-Ang University; Seoul 156-756 Korea
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Kar S, Wang M, Ham SW, Carr BI. H32, a non-quinone sulfone analog of vitamin K3, inhibits human hepatoma cell growth by inhibiting Cdc25 and activating ERK. Cancer Biol Ther 2014; 5:1340-7. [PMID: 16969075 DOI: 10.4161/cbt.5.10.3223] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We previously synthesized a K-vitamin derivative, Cpd 5, which was a potent growth inhibitor of human tumor cells, including Hep3B hepatoma cells. However, being a quinone compound, Cpd 5 has the potential for generating toxic reactive oxygen species (ROS). We therefore synthesized a nonquinone sulfone derivative, H32, which has a sufone group substituting the quinone. The IC50 of H32 for Hep3B cells was found to be 2.5 microM, which was 2.5 and 3.2 times more potent than Cpd 5 and vitamin K3 respectively. It induced apoptosis in Hep3B cells but did not generate ROS when compared to Cpd 5. Interestingly, under similar culture conditions, normal rat hepatocytes were 14-fold more and 7-fold more resistant to the growth inhibitory effects of H32 than Hep3B and PLC/PRF5 cells respectively. H32 preferentially inhibited the activities of the cell cycle controlling Cdc25A phosphatase likely by binding to its catalytic cysteine. As a consequence, it induced inhibitory tyrosine phosphorylation of the Cdc25 substrate kinases Cdk2 and Cdk4 in Hep3B cells and the cells undergo an arrest in the G1 phase of the cell cycle. H32 also induced persistent phosphorylation of the MAPK protein ERK1/2, but marginal JNK1/2 and p38 phosphorylation. The ERK inhibitor U0126, added at least 30 min prior to H32, antagonized the growth inhibition induced by H32. However, the JNK and p38 inhibitors, JNKI-II and SB203580, were not able to antagonize H32 induced growth inhibition. Thus, H32 differentially inhibited growth of normal and liver tumor cells by preferentially inhibiting the actions of Cdc25 phosphatases and inducing persistent ERK phosphorylation.
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Affiliation(s)
- Siddhartha Kar
- Liver Cancer Center, T. E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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Kang S, Moon Y, Ji T, Ha S, Lim DH, Ham SW. Orally Applied Novel Organogermanium Improves Skin Inflammation in NC/Nga Mice with Atopic Dermatitis. B KOREAN CHEM SOC 2013. [DOI: 10.5012/bkcs.2013.34.1.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Min NY, Kim JH, Choi JH, Liang W, Ko YJ, Rhee S, Bang H, Ham SW, Park AJ, Lee KH. Selective death of cancer cells by preferential induction of reactive oxygen species in response to (-)-epigallocatechin-3-gallate. Biochem Biophys Res Commun 2012; 421:91-7. [PMID: 22487794 DOI: 10.1016/j.bbrc.2012.03.120] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 03/26/2012] [Indexed: 11/18/2022]
Abstract
(-)-Epigallocatechin-3-gallate (EGCG) induces apoptosis in cancer cells without adversely affecting normal cells. Understanding the cancer-specific cytotoxic activity of EGCG is very important in defining the mechanism of tumorigenesis and identifying superb chemotherapeutic agents against cancer. We comparatively assayed human telomerase reverse transcriptase (hTERT)-mediated apoptosis by EGCG-induced reactive oxygen species (ROS) in normal cells and cancer cells. EGCG showed differential levels of ROS induction between the cell types; ROS, especially hydrogen peroxide, was highly induced in cancer cells, while it was not in normal cells. In addition, the higher level of ROS down-regulated hTERT via binding of CCCTC binding factor (CTCF) to the core promoter region of hTERT, which repressed hTERT expression. CTCF binding was epigenetically controlled by the demethylation of the previously hypermethylated site for CTCF, which was induced by down-regulation of DNA methyltransferase 1 (DNMT1). In contrast, hTERT down-regulation was not observed in normal cells. These results suggest that preferential death of cancer cells by EGCG could be caused by the cancer-specific induction of ROS and epigenetic modulation of expression of apoptosis-related genes, such as hTERT.
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Affiliation(s)
- Na Young Min
- Department of Life Science, College of Natural Science, Chung-Ang University, Seoul 156-756, Republic of Korea
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Bhattarai BR, Kafle B, Hwang JS, Ham SW, Lee KH, Park H, Han IO, Cho H. Novel thiazolidinedione derivatives with anti-obesity effects: Dual action as PTP1B inhibitors and PPAR-γ activators. Bioorg Med Chem Lett 2010; 20:6758-63. [DOI: 10.1016/j.bmcl.2010.08.130] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/14/2010] [Accepted: 08/27/2010] [Indexed: 10/19/2022]
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Lim DH, Li M, Seo JA, Lim KM, Ham SW. A novel organogermanium protected atopic dermatitis induced by oxazolone. Bioorg Med Chem Lett 2010; 20:4032-4. [PMID: 20547454 DOI: 10.1016/j.bmcl.2010.05.097] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/20/2010] [Accepted: 05/24/2010] [Indexed: 01/14/2023]
Abstract
Atopic dermatitis (AD) is a chronic inflammatory disease of the skin that is often associated with other atopic diseases, such as asthma and allergic rhinitis. Although topical steroids have widely been prescribed for patients with AD, skin abnormalities are frequently observed after prolonged steroid treatment. In this study, a novel water-soluble organogermanium compound (Ge-Vit) was prepared because organogermanium is a known INF-gamma inducer. The Ge-Vit treatment decreased the basal TEWL and IgE production and attenuated the disruption of the skin barrier function in a murine model of chronic contact dermatitis. The histological examination further supported the anti-AD activities. These results suggested that Ge-Vit can be a useful drug candidate for treating atopic dermatitis.
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Affiliation(s)
- Doo Hyeon Lim
- Department of Chemistry, College of Natural Science, Chung-Ang University, Seoul 156-756, Republic of Korea
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Park H, Bhattarai BR, Ham SW, Cho H. Structure-based virtual screening approach to identify novel classes of PTP1B inhibitors. Eur J Med Chem 2009; 44:3280-4. [DOI: 10.1016/j.ejmech.2009.02.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 02/02/2009] [Accepted: 02/12/2009] [Indexed: 11/26/2022]
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Park H, Li M, Choi J, Cho H, Ham SW. Structure-based virtual screening approach to identify novel classes of Cdc25B phosphatase inhibitors. Bioorg Med Chem Lett 2009; 19:4372-5. [PMID: 19500977 DOI: 10.1016/j.bmcl.2009.05.078] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 05/08/2009] [Accepted: 05/20/2009] [Indexed: 11/25/2022]
Abstract
Discovery of Cdc25B phosphatase inhibitors has been actively pursued with the aim to develop anticancer agents. We have been able to identify eight novel Cdc25B inhibitors by means of a computer-aided drug design protocol involving the virtual screening with docking simulations under consideration of the effects of ligand solvation in the binding free energy function. Structural features relevant to the interactions of the newly identified inhibitors with the active-site residues of Cdc25B are also discussed in detail.
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Affiliation(s)
- Hwangseo Park
- Department of Bioscience and Biotechnology, Sejong University, Seoul 143-747, Republic of Korea
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Bhattarai BR, Shrestha S, Ham SW, Kim KR, Cheon HG, Lee KH, Cho H. 2-O-Carboxymethylpyrogallol derivatives as PTP1B inhibitors with antihyperglycemic activity. Bioorg Med Chem Lett 2007; 17:5357-60. [PMID: 17728130 DOI: 10.1016/j.bmcl.2007.08.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 08/03/2007] [Accepted: 08/06/2007] [Indexed: 01/18/2023]
Abstract
2-O-carboxymethylpyrogallol derivatives (4-17) were synthesized, with their in vitro inhibitory activities against PTP1B and in vivo antihyperglycemic effects examined. Compound 14, the most potent among the series, showed a K(i) value of 1.1 microM against PTP1B, 7-fold lower than that against TC-PTP. When compound 14 was fed to a high-fat diet-induced diabetic mouse model, significant improvements were observed in both the fasting glucose level and glucose tolerance.
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Affiliation(s)
- Bharat Raj Bhattarai
- Department of Chemistry and Institute of Molecular Cell Biology, Inha University, Incheon 402-751, Republic of Korea
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Abstract
We report on the fluorinated form of NSC 95397 as a Cdc25B inhibitor, which is predicted to be only an arylator of cysteine-containing proteins, without generating reactive oxygen species.
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Affiliation(s)
- Hwangseo Park
- Department of Bioscience and Biotechnology, Sejong University, 98 Kunja-Dong, Kwangjin-Ku, Seoul 143-747, Republic of Korea
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Kar S, Wang M, Ham SW, Carr BI. Fluorinated Cpd 5, a pure arylating K-vitamin derivative, inhibits human hepatoma cell growth by inhibiting Cdc25 and activating MAPK. Biochem Pharmacol 2006; 72:1217-27. [PMID: 16930563 DOI: 10.1016/j.bcp.2006.07.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Revised: 06/30/2006] [Accepted: 07/26/2006] [Indexed: 10/24/2022]
Abstract
We previously synthesized several K-vitamin derivatives, which are potent growth inhibitors of human tumor cells, including Hep3B human hepatoma cells. Among these, Cpd 5 was the most potent. However, being a quinone derivative, Cpd 5 has the potential for generating toxic reactive oxygen species (ROS). We therefore synthesized a fluorinated derivative of Cpd 5, F-Cpd 5. The calculated reduction potential of F-Cpd 5 was much higher than that for Cpd 5 and it was not predicted to generate ROS. This was supported by our observation that F-Cpd 5 generated significantly lower ROS than Cpd 5. F-Cpd 5 was three times more potent than Cpd 5 in inhibiting Hep3B cell growth. Interestingly, under identical culture conditions, F-Cpd 5 inhibited mitogen-induced DNA synthesis in normal rat hepatocytes 12-fold less potently than Hep3B cells. F-Cpd 5 was found to induce caspase-3 cleavage and nuclear DNA laddering, evidences for apoptosis. It preferentially inhibited the activities of the cell cycle controlling phosphatases Cdc25A and Cdc25B, by binding to their catalytic cysteines. Consequently, inhibitory tyrosine phosphorylation of the Cdc25 substrate kinases Cdk2 and Cdk4 were induced. F-Cpd 5 also induced phosphorylation of the MAPK proteins ERK1/2, JNK1/2 and p38 in Hep3B cells and the MAPK inhibitors (U0126, JNKI-II, and SB 203580) antagonized its growth inhibition. F-Cpd 5 inhibited the action of cytosolic ERK phosphatase activity, which likely caused the ERK phosphorylation. F-Cpd 5 thus differentially inhibited growth of normal and tumor cells by preferentially inhibiting the actions of Cdc25A and Cdc25B phosphatases and inducing MAPK phosphorylation.
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Affiliation(s)
- Siddhartha Kar
- Liver Cancer Center, Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh PA, USA
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Ham SW, Choe JI, Wang MF, Peyregne V, Carr BI. Fluorinated quinoid inhibitor: possible "pure" arylator predicted by the simple theoretical calculation. Bioorg Med Chem Lett 2005; 14:4103-5. [PMID: 15225735 DOI: 10.1016/j.bmcl.2004.05.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2004] [Revised: 05/07/2004] [Accepted: 05/07/2004] [Indexed: 11/26/2022]
Abstract
We report on the fluorinated form of Cpd 5 as a cell growth inhibitor. This compound is 3-fold more potent than the parent Cpd 5 and is predicted, using the semi-empirical AM1 method to be only an arylator of cysteine-containing proteins, without generating reactive oxygen species.
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Affiliation(s)
- Seung Wook Ham
- Liver Cancer Center, Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA
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Naganathan S, Hershline R, Ham SW, Dowd P. Active site of vitamin K. Regiospecific oxygenation of vitamin K hydroquinone in its role as carboxylase cofactor. J Am Chem Soc 2002. [DOI: 10.1021/ja00066a068] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Dowd P, Ham SW, Hershline R. Role of oxygen in the vitamin K-dependent carboxylation reaction: incorporation of a second atom of oxygen 18 from molecular oxygen-18O2 into vitamin K oxide during carboxylase activity. J Am Chem Soc 2002. [DOI: 10.1021/ja00046a001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Arnett EM, Dowd P, Flowers RA, Ham SW, Naganathan S. Thermochemical confirmation of the mechanism of activation by vitamin K. J Am Chem Soc 2002. [DOI: 10.1021/ja00049a075] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Ham SW, Chang W, Dowd P. 4-Methylenecyclopentane-1,3-diyl: first direct observation of a semilocalized, homotrimethylenemethane 1,3-diradical. J Am Chem Soc 2002. [DOI: 10.1021/ja00193a072] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Protein tyrosine phosphatase inactivators are of interest as research tools and as therapeutic agents. In this study, the effect of sulfone analogue of naphthoquinone on the activities of PTP1B and other PTPs was examined. The results indicated that this compound selectively and irreversibly inactivated the PTP1B with the dissociation constant Ki of 3.5 microM and the inactivation rate constant kinact of 2.2 x 10(-2) sec-1.
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Affiliation(s)
- S W Ham
- Department of Chemistry, Chung-Ang University, Seoul, Korea
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Abstract
cdc25A and cdc25B were significantly overexpressed in certain types of cancers, and they represent potential therapeutic targets for anticancer drug. In this study, naphthoquinone analogs as cdc25A phosphatase inactivators were investigated.
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Affiliation(s)
- S W Ham
- Department of Chemistry, Chung-Ang University, Seoul, Korea
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Ham SW, Lee KJ, Yoo JS. One-Pot Synthesis of 2,4,6-Trimethoxybenzyl Thioether from Thioacetate. SYNTHETIC COMMUN 1996. [DOI: 10.1080/00397919608003574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
Energy transfer provides an arrow in the metabolism of living systems. Direct energetic coupling of chemical transformations, such that the free energy generated in one reaction is channeled to another, is the essence of energy transfer, whereas the purpose is the production of high-energy chemical intermediates. Vitamin K provides a particularly instructive example of energy transfer. A key principle at work in the vitamin K system can be termed "base strength amplification." In the base strength amplification sequence, the free energy of oxygenation of vitamin K hydroquinone (vitamin KH2) is used to transform a weak base to a strong base in order to effect proton removal from selected glutamate (Glu) residues in the blood-clotting proteins.
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Affiliation(s)
- P Dowd
- Department of Chemistry, University of Pittsburgh, PA 15260, USA
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Abstract
Vitamin K is the blood-clotting vitamin. The mechanism of action of vitamin K is discussed in terms of a new carbanion model that mimics the proton abstraction from the gamma position of protein-bound glutamate. This is the essential step leading to carboxylation and activation of the blood-clotting proteins. The model comprises an oxygenation that is coupled to carbon-carbon bond formation, as is the oxygenation of vitamin K hydroquinone to vitamin K oxide. The model hypothesis is also supported by the mechanism of inhibition of the carboxylase by HCN, which acts as an acid-base inhibitor rather than a metal-complexing inhibitor. The new model postulates a dioxetane intermediate that explains the presence of a second atom of 18O (from 18O2) incorporated into vitamin K oxide in the course of the enzymatic carboxylation. Finally, the chemistry developed here has been used to define the active site of vitamin K hydroquinone as the carbon-carbon bond adjacent to the methyl group.
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Affiliation(s)
- P Dowd
- Department of Chemistry, University of Pittsburgh, Pennsylvania 15260, USA
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Abstract
We have discovered a novel, spontaneous model oxidation that leads to a powerful base capable of carrying out a carbon-carbon bond forming condensation reaction analogous to that observed in the vitamin K-mediated carboxylation of glutamate. The model sequence incorporates a novel base-strength enhancement sequence and it implicates molecular oxygen as the initiating factor in the vitamin K-dependent carboxylation. When the oxygenation is carried out under an atmosphere of (18)O2, two atoms of (18)O are incorporated into the vitamin K oxide product. Selective (18)O labelling defines the carbonyl group next to methyl as the active site of the vitamin K.
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Affiliation(s)
- P Dowd
- Department of Chemistry, University of Pittsburgh, PA 15260, USA
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Abstract
Cyanide is a competitive inhibitor of carbon dioxide in the vitamin K-dependent glutamate carboxylase system, which plays a central role in the function of the blood clotting cascade. The mechanism of cyanide inhibition has been obscure for some time. At pH 7.2, cyanide (pKa = 9.21) will exist in solution as hydrogen cyanide to the extent of 99%. Hydrogen cyanide is linear triatomic molecule able to serve as a surrogate for carbon dioxide at the enzyme active site. Hydrogen cyanide is an acid; it will quench the deprotonated glutamate carbanion precursor to gamma-carboxyglutamate, resulting in inhibition of the carboxylation sequence.
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Affiliation(s)
- P Dowd
- Department of Chemistry, University of Pittsburgh, PA 15260
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