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Ma APY, Yeung CLS, Tey SK, Mao X, Wong SWK, Ng TH, Ko FCF, Kwong EML, Tang AHN, Ng IOL, Cai SH, Yun JP, Yam JWP. Suppression of ACADM-Mediated Fatty Acid Oxidation Promotes Hepatocellular Carcinoma via Aberrant CAV1/SREBP1 Signaling. Cancer Res 2021; 81:3679-3692. [PMID: 33975883 DOI: 10.1158/0008-5472.can-20-3944] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 03/24/2021] [Accepted: 04/27/2021] [Indexed: 12/24/2022]
Abstract
Lipid accumulation exacerbates tumor development, as it fuels the proliferative growth of cancer cells. The role of medium-chain acyl-CoA dehydrogenase (ACADM), an enzyme that catalyzes the first step of mitochondrial fatty acid oxidation, in tumor biology remains elusive. Therefore, investigating its mode of dysregulation can shed light on metabolic dependencies in cancer development. In hepatocellular carcinoma (HCC), ACADM was significantly underexpressed, correlating with several aggressive clinicopathologic features observed in patients. Functionally, suppression of ACADM promoted HCC cell motility with elevated triglyceride, phospholipid, and cellular lipid droplet levels, indicating the tumor suppressive ability of ACADM in HCC. Sterol regulatory element-binding protein-1 (SREBP1) was identified as a negative transcriptional regulator of ACADM. Subsequently, high levels of caveolin-1 (CAV1) were observed to inhibit fatty acid oxidation, which revealed its role in regulating lipid metabolism. CAV1 expression negatively correlated with ACADM and its upregulation enhanced nuclear accumulation of SREBP1, resulting in suppressed ACADM activity and contributing to increased HCC cell aggressiveness. Administration of an SREBP1 inhibitor in combination with sorafenib elicited a synergistic antitumor effect and significantly reduced HCC tumor growth in vivo. These findings indicate that deregulation of fatty acid oxidation mediated by the CAV1/SREBP1/ACADM axis results in HCC progression, which implicates targeting fatty acid metabolism to improve HCC treatment. SIGNIFICANCE: This study identifies tumor suppressive effects of ACADM in hepatocellular carcinoma and suggests promotion of β-oxidation to diminish fatty acid availability to cancer cells could be used as a therapeutic strategy.
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Affiliation(s)
- Angel P Y Ma
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Cherlie L S Yeung
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Sze Keong Tey
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Xiaowen Mao
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Samuel W K Wong
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Tung Him Ng
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Frankie C F Ko
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Ernest M L Kwong
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Alexander H N Tang
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Irene Oi-Lin Ng
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.,State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong, China
| | - Shao Hang Cai
- Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jing Ping Yun
- Department of Pathology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Judy W P Yam
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China. .,State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong, China
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Leung YH, Guo MY, Ma APY, Ng AMC, Djurišić AB, Degger N, Leung FCC. Transmission electron microscopy artifacts in characterization of the nanomaterial-cell interactions. Appl Microbiol Biotechnol 2017; 101:5469-5479. [PMID: 28497205 DOI: 10.1007/s00253-017-8305-6] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 04/18/2017] [Accepted: 04/21/2017] [Indexed: 11/26/2022]
Abstract
We investigated transmission electron microscopy artifacts obtained using standard sample preparation protocols applied to the investigation of Escherichia coli cells exposed to common nanomaterials, such as TiO2, Ag, ZnO, and MgO. While the common protocols for some nanomaterials result only in known issues of nanomaterial-independent generation of anomalous deposits due to fixation and staining, for others, there are reactions between the nanomaterial and chemicals used for post-fixation or staining. Only in the case of TiO2 do we observe only the known issues of nanomaterial-independent generation of anomalous deposits due to exceptional chemical stability of this material. For the other three nanomaterials, different artifacts are observed. For each of those, we identify causes of the observed problems and suggest alternative sample preparation protocols to avoid artifacts arising from the sample preparation, which is essential for correct interpretation of the obtained images and drawing correct conclusions on cell-nanomaterial interactions. Finally, we propose modified sample preparation and characterization protocols for comprehensive and conclusive investigations of nanomaterial-cell interactions using electron microscopy and for obtaining clear and unambiguous revelation whether the nanomaterials studied penetrate the cells or accumulate at the cell membranes. In only the case of MgO and ZnO, the unambiguous presence of Zn and Mg could be observed inside the cells.
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Affiliation(s)
- Yu Hang Leung
- Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong
| | - Mu Yao Guo
- Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong
- Department of Physics, Southern University of Science and Technology of China, Shenzhen, China
| | - Angel P Y Ma
- School of Biological Sciences, University of Hong Kong, Pokfulam Road, Hong Kong
| | - Alan M C Ng
- Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong
- Department of Physics, Southern University of Science and Technology of China, Shenzhen, China
| | | | - Natalie Degger
- School of Biological Sciences, University of Hong Kong, Pokfulam Road, Hong Kong
| | - Frederick C C Leung
- School of Biological Sciences, University of Hong Kong, Pokfulam Road, Hong Kong
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Leung YH, Xu X, Ma APY, Liu F, Ng AMC, Shen Z, Gethings LA, Guo MY, Djurišić AB, Lee PKH, Lee HK, Chan WK, Leung FCC. Toxicity of ZnO and TiO 2 to Escherichia coli cells. Sci Rep 2016; 6:35243. [PMID: 27731373 PMCID: PMC5378928 DOI: 10.1038/srep35243] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 09/27/2016] [Indexed: 12/19/2022] Open
Abstract
We performed a comprehensive investigation of the toxicity of ZnO and TiO2 nanoparticles using Escherichia coli as a model organism. Both materials are wide band gap n-type semiconductors and they can interact with lipopolysaccharide molecules present in the outer membrane of E. coli, as well as produce reactive oxygen species (ROS) under UV illumination. Despite the similarities in their properties, the response of the bacteria to the two nanomaterials was fundamentally different. When the ROS generation is observed, the toxicity of nanomaterial is commonly attributed to oxidative stress and cell membrane damage caused by lipid peroxidation. However, we found that significant toxicity does not necessarily correlate with up-regulation of ROS-related proteins. TiO2 exhibited significant antibacterial activity, but the protein expression profile of bacteria exposed to TiO2 was different compared to H2O2 and the ROS-related proteins were not strongly expressed. On the other hand, ZnO exhibited lower antibacterial activity compared to TiO2, and the bacterial response involved up-regulating ROS-related proteins similar to the bacterial response to the exposure to H2O2. Reasons for the observed differences in toxicity and bacterial response to the two metal oxides are discussed.
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Affiliation(s)
- Yu Hang Leung
- Dept. of Physics, Univ. of Hong Kong, Pokfulam Road, Hong Kong
| | - Xiaoying Xu
- School of Energy and Environment, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Angel P. Y. Ma
- School of Biological Sciences, Univ. of Hong Kong, Pokfulam Road, Hong Kong
| | - Fangzhou Liu
- Dept. of Physics, Univ. of Hong Kong, Pokfulam Road, Hong Kong
| | - Alan M. C. Ng
- Dept. of Physics, Univ. of Hong Kong, Pokfulam Road, Hong Kong
- Dept. of Physics, South University of Science and Technology of China, Shenzhen, China
| | - Zhiyong Shen
- School of Energy and Environment, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Lee A. Gethings
- Pharmaceutical and Life Sciences Division, Waters Corporation, Manchester, UK
| | - Mu Yao Guo
- Dept. of Physics, Univ. of Hong Kong, Pokfulam Road, Hong Kong
- Dept. of Physics, South University of Science and Technology of China, Shenzhen, China
| | | | - Patrick K. H. Lee
- School of Energy and Environment, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Hung Kay Lee
- Dept. of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | - Wai Kin Chan
- Dept. of Chemistry, Univ. of Hong Kong, Pokfulam Road, Hong Kong
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Leung YH, Yung MMN, Ng AMC, Ma APY, Wong SWY, Chan CMN, Ng YH, Djurišić AB, Guo M, Wong MT, Leung FCC, Chan WK, Leung KMY, Lee HK. Toxicity of CeO2 nanoparticles - the effect of nanoparticle properties. J Photochem Photobiol B 2015; 145:48-59. [PMID: 25768267 DOI: 10.1016/j.jphotobiol.2015.01.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 01/05/2015] [Accepted: 01/27/2015] [Indexed: 10/23/2022]
Abstract
Conflicting reports on the toxicity of CeO2 nanomaterials have been published in recent years, with some studies finding CeO2 nanoparticles to be toxic, while others found it to have protective effects against oxidative stress. To investigate the possible reasons for this, we have performed a comprehensive study on the physical and chemical properties of nanosized CeO2 from three different suppliers as well as CeO2 synthesized by us, and tested their toxicity. For toxicity tests, we have studied the effects of CeO2 nanoparticles on a Gram-negative bacterium Escherichia coli in the dark, under ambient and UV illuminations. We have also performed toxicity tests on the marine diatom Skeletonema costatum under ambient and UV illuminations. We found that the CeO2 nanoparticle samples exhibited significantly different toxicity, which could likely be attributed to the differences in interactions with cells, and possibly to differences in nanoparticle compositions. Our results also suggest that toxicity tests on bacteria may not be suitable for predicting the ecotoxicity of nanomaterials. The relationship between the toxicity and physicochemical properties of the nanoparticles is explicitly discussed in the light of the current results.
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Affiliation(s)
- Yu Hang Leung
- Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
| | - Mana M N Yung
- School of Biological Sciences and the Swire Institute of Marine Science, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Alan M C Ng
- Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China; Department of Physics, South University of Science and Technology of China, 1088 Xueyuan Ave, Nanshan, Shenzhen, China
| | - Angel P Y Ma
- School of Biological Sciences and the Swire Institute of Marine Science, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Stella W Y Wong
- School of Biological Sciences and the Swire Institute of Marine Science, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Charis M N Chan
- School of Biological Sciences and the Swire Institute of Marine Science, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Yip Hang Ng
- Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | | | - Muyao Guo
- Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China; Department of Physics, South University of Science and Technology of China, 1088 Xueyuan Ave, Nanshan, Shenzhen, China
| | - Mabel Ting Wong
- School of Biological Sciences and the Swire Institute of Marine Science, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Frederick C C Leung
- School of Biological Sciences and the Swire Institute of Marine Science, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Wai Kin Chan
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Kenneth M Y Leung
- School of Biological Sciences and the Swire Institute of Marine Science, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Hung Kay Lee
- Department of Chemistry, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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Hsu A, Liu F, Leung YH, Ma APY, Djurišić AB, Leung FCC, Chan WK, Lee HK. Is the effect of surface modifying molecules on antibacterial activity universal for a given material? Nanoscale 2014; 6:10323-10331. [PMID: 25072881 DOI: 10.1039/c4nr02366h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Antibacterial activity of nanomaterials is strongly dependent on their properties, and their stability and toxicity can be varied using surface coatings. We investigated the effect of different surface modifying molecules on the antibacterial properties of two ZnO nanoparticle samples. We found that the starting surface properties of the nanoparticles have significant effects on the attachment of the surface modifying molecules and consequent antibacterial activity. Two out of five investigated surface modifying molecules not only had a significant difference in the magnitude of their effect on different nanoparticles, but also resulted in the opposite effects on two ZnO nanoparticle samples (an enhancement of antibacterial activity for one and a reduction of antibacterial activity for the other ZnO sample). This indicates that no general rule on the effect of a specific molecule on the toxicity of a metal oxide nanoparticle can be derived without knowing the nanoparticle properties, due to the fact that surface modifier attachment onto the surface is affected by the initial surface properties.
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Affiliation(s)
- Alexander Hsu
- Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong.
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Leung YH, Ng AMC, Xu X, Shen Z, Gethings LA, Wong MT, Chan CMN, Guo MY, Ng YH, Djurišić AB, Lee PKH, Chan WK, Yu LH, Phillips DL, Ma APY, Leung FCC. Mechanisms of antibacterial activity of MgO: non-ROS mediated toxicity of MgO nanoparticles towards Escherichia coli. Small 2014; 10:1171-83. [PMID: 24344000 DOI: 10.1002/smll.201302434] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [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: 08/08/2013] [Revised: 10/28/2013] [Indexed: 05/09/2023]
Abstract
The toxicity of metal oxide nanomaterials and their antimicrobial activity is attracting increasing attention. Among these materials, MgO is particularly interesting as a low cost, environmentally-friendly material. The toxicity of MgO, similar to other metal oxide nanomaterials, is commonly attributed to the production of reactive oxygen species (ROS). We investigated the toxicity of three different MgO nanoparticle samples, and clearly demonstrated robust toxicity towards Escherichia coli bacterial cells in the absence of ROS production for two MgO nanoparticle samples. Proteomics data also clearly demonstrate the absence of oxidative stress and indicate that the primary mechanism of cell death is related to the cell membrane damage, which does not appear to be due to lipid peroxidation.
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Affiliation(s)
- Yu Hang Leung
- Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong
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