64
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Multi-walled carbon nanotube induces nitrative DNA damage in human lung epithelial cells via HMGB1-RAGE interaction and Toll-like receptor 9 activation

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background

          Carbon nanotube (CNT) is used for various industrial purposes, but exhibits carcinogenic effects in experimental animals. Chronic inflammation in the respiratory system may participate in CNT-induced carcinogenesis. 8-Nitroguanine (8-nitroG) is a mutagenic DNA lesion formed during inflammation. We have previously reported that multi-walled CNT (MWCNT) induced 8-nitroG formation in lung epithelial cells and this process involved endocytosis. To clarify the mechanism of CNT-induced carcinogenesis, we examined the role of Toll-like receptor (TLR) 9, which resides in endosomes and lysosomes, in 8-nitroG formation in human lung epithelial cell lines.

          Methods

          We performed immunocytochemistry to examine 8-nitroG formation in A549 and HBEpC cells treated with MWCNT with a length of 1-2 μm (CNT-S) or 5-15 μm (CNT-L) and a diameter of 20-40 nm. We examined inhibitory effects of endocytosis inhibitors, small interfering RNA (siRNA) for TLR9, and antibodies against high-mobility group box-1 (HMGB1) and receptor for advanced glycation end-products (RAGE) on 8-nitroG formation. The release of HMGB1 and double-stranded DNA (dsDNA) into the culture supernatant from MWCNT-treated cells was examined by ELISA and fluorometric analysis, respectively. The association of these molecules was examined by double immunofluorescent staining and co-immunoprecipitation.

          Results

          CNT-L significantly increased 8-nitroG formation at 0.05 μg/ml in A549 cells and its intensity reached a maximum at 1 μg/ml. CNT-L tended to induce stronger cytotoxicity and 8-nitroG formation than CNT-S. Endocytosis inhibitors, TLR9 siRNA and antibodies against HMGB1 and RAGE largely reduced MWCNT-induced 8-nitroG formation. MWCNT increased the release of HMGB1 and dsDNA from A549 cells into culture supernatant. The culture supernatant of MWCNT-exposed cells induced 8-nitroG formation in fresh A549 cells. Double immunofluorescent staining and co-immunoprecipitation showed that TLR9 was associated with HMGB1 and RAGE in lysosomes of MWCNT-treated cells.

          Conclusions

          MWCNT induces injury or necrosis of lung epithelial cells, which release HMGB1 and DNA into the extracellular space. The HMGB1-DNA complex binds to RAGE on neighboring cells and then CpG DNA is recognized by TLR9 in lysosomes, leading to generation of nitric oxide and 8-nitroG formation. This is the first study demonstrating that TLR9 and related molecules participate in MWCNT-induced genotoxicity and may contribute to carcinogenesis.

          Electronic supplementary material

          The online version of this article (doi:10.1186/s12989-016-0127-7) contains supplementary material, which is available to authorized users.

          Related collections

          Most cited references47

          • Record: found
          • Abstract: found
          • Article: not found

          Radical causes of cancer.

          Free radicals are ubiquitous in our body and are generated by normal physiological processes, including aerobic metabolism and inflammatory responses, to eliminate invading pathogenic microorganisms. Because free radicals can also inflict cellular damage, several defences have evolved both to protect our cells from radicals--such as antioxidant scavengers and enzymes--and to repair DNA damage. Understanding the association between chronic inflammation and cancer provides insights into the molecular mechanisms involved. In particular, we highlight the interaction between nitric oxide and p53 as a crucial pathway in inflammatory-mediated carcinogenesis.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Inflammation: gearing the journey to cancer.

            Chronic inflammation plays a multifaceted role in carcinogenesis. Mounting evidence from preclinical and clinical studies suggests that persistent inflammation functions as a driving force in the journey to cancer. The possible mechanisms by which inflammation can contribute to carcinogenesis include induction of genomic instability, alterations in epigenetic events and subsequent inappropriate gene expression, enhanced proliferation of initiated cells, resistance to apoptosis, aggressive tumor neovascularization, invasion through tumor-associated basement membrane and metastasis, etc. Inflammation-induced reactive oxygen and nitrogen species cause damage to important cellular components (e.g., DNA, proteins and lipids), which can directly or indirectly contribute to malignant cell transformation. Overexpression, elevated secretion, or abnormal activation of proinflammatory mediators, such as cytokines, chemokines, cyclooxygenase-2, prostaglandins, inducible nitric oxide synthase, and nitric oxide, and a distinct network of intracellular signaling molecules including upstream kinases and transcription factors facilitate tumor promotion and progression. While inflammation promotes development of cancer, components of the tumor microenvironment, such as tumor cells, stromal cells in surrounding tissue and infiltrated inflammatory/immune cells generate an intratumoral inflammatory state by aberrant expression or activation of some proinflammatory molecules. Many of proinflammatory mediators, especially cytokines, chemokines and prostaglandins, turn on the angiogenic switches mainly controlled by vascular endothelial growth factor, thereby inducing inflammatory angiogenesis and tumor cell-stroma communication. This will end up with tumor angiogenesis, metastasis and invasion. Moreover, cellular microRNAs are emerging as a potential link between inflammation and cancer. The present article highlights the role of various proinflammatory mediators in carcinogenesis and their promise as potential targets for chemoprevention of inflammation-associated carcinogenesis.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Safety assessment for nanotechnology and nanomedicine: concepts of nanotoxicology.

              Nanotechnology, nanomedicine and nanotoxicology are complementary disciplines aimed at the betterment of human life. However, concerns have been expressed about risks posed by engineered nanomaterials (ENMs), their potential to cause undesirable effects, contaminate the environment and adversely affect susceptible parts of the population. Information about toxicity and biokinetics of nano-enabled products combined with the knowledge of unintentional human and environmental exposure or intentional delivery for medicinal purposes will be necessary to determine real or perceived risks of nanomaterials. Yet, results of toxicological studies using only extraordinarily high experimental doses have to be interpreted with caution. Key concepts of nanotoxicology are addressed, including significance of dose, dose rate, and biokinetics, which are exemplified by specific findings of ENM toxicity, and by discussing the importance of detailed physico-chemical characterization of nanoparticles, specifically surface properties. Thorough evaluation of desirable versus adverse effects is required for safe applications of ENMs, and major challenges lie ahead to answer key questions of nanotoxicology. Foremost are assessment of human and environmental exposure, and biokinetics or pharmacokinetics, identification of potential hazards, and biopersistence in cells and subcellular structures to perform meaningful risk assessments. A specific example of multiwalled carbon nanotubes (MWCNT) illustrates the difficulty of extrapolating toxicological results. MWCNT were found to cause asbestos-like effects of the mesothelium following intracavitary injection of high doses in rodents. The important question of whether inhaled MWCNT will translocate to sensitive mesothelial sites has not been answered yet. Even without being able to perform a quantitative risk assessment for ENMs, due to the lack of sufficient data on exposure, biokinetics and organ toxicity, until we know better it should be made mandatory to prevent exposure by appropriate precautionary measures/regulations and practicing best industrial hygiene to avoid future horror scenarios from environmental or occupational exposures. Similarly, safety assessment for medical applications as key contribution of nanotoxicology to nanomedicine relies heavily on nano-specific toxicological concepts and findings and on a multidisciplinary collaborative approach involving material scientists, physicians and toxicologists.
                Bookmark

                Author and article information

                Contributors
                +81-59-231-5011 , y-hiraku@doc.medic.mie-u.ac.jp
                feiyeguo@hotmail.com
                maning@suzuka-u.ac.jp
                311117@m.mie-u.ac.jp
                wsmkv2008@gmail.com
                kawanisi@suzuka-u.ac.jp
                mmurata@doc.medic.mie-u.ac.jp
                Journal
                Part Fibre Toxicol
                Part Fibre Toxicol
                Particle and Fibre Toxicology
                BioMed Central (London )
                1743-8977
                29 March 2016
                29 March 2016
                2015
                : 13
                : 16
                Affiliations
                [ ]Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507 Japan
                [ ]Faculty of Nursing Science, Suzuka University of Medical Science, 3500-3 Minami-Tamagaki-cho, Suzuka, Mie 513-8670 Japan
                [ ]Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, 3500-3 Minami-Tamagaki-cho, Suzuka, Mie 513-8670 Japan
                Article
                127
                10.1186/s12989-016-0127-7
                4812657
                27026438
                f119c569-c78e-4e09-a79a-52bea8cc57ec
                © Hiraku et al. 2016

                Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

                History
                : 2 June 2015
                : 15 March 2016
                Funding
                Funded by: Ministry of Education, Culture, Sports, Science and Technology of Japan
                Award ID: 25670313
                Award Recipient :
                Categories
                Research
                Custom metadata
                © The Author(s) 2016

                Toxicology
                carbon nanotube,endocytosis,cytotoxicity,high-mobility group box-1, receptor for advanced glycation end-products, toll-like receptor,nitric oxide,dna damage,8-nitroguanine,carcinogenesis

                Comments

                Comment on this article