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Besnard C, Marie A, Sasidharan S, Harper RA, Shelton RM, Landini G, Korsunsky AM. Synchrotron X-ray Studies of the Structural and Functional Hierarchies in Mineralised Human Dental Enamel: A State-of-the-Art Review. Dent J (Basel) 2023; 11:98. [PMID: 37185477 PMCID: PMC10137518 DOI: 10.3390/dj11040098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/19/2023] [Accepted: 03/28/2023] [Indexed: 05/17/2023] Open
Abstract
Hard dental tissues possess a complex hierarchical structure that is particularly evident in enamel, the most mineralised substance in the human body. Its complex and interlinked organisation at the Ångstrom (crystal lattice), nano-, micro-, and macro-scales is the result of evolutionary optimisation for mechanical and functional performance: hardness and stiffness, fracture toughness, thermal, and chemical resistance. Understanding the physical-chemical-structural relationships at each scale requires the application of appropriately sensitive and resolving probes. Synchrotron X-ray techniques offer the possibility to progress significantly beyond the capabilities of conventional laboratory instruments, i.e., X-ray diffractometers, and electron and atomic force microscopes. The last few decades have witnessed the accumulation of results obtained from X-ray scattering (diffraction), spectroscopy (including polarisation analysis), and imaging (including ptychography and tomography). The current article presents a multi-disciplinary review of nearly 40 years of discoveries and advancements, primarily pertaining to the study of enamel and its demineralisation (caries), but also linked to the investigations of other mineralised tissues such as dentine, bone, etc. The modelling approaches informed by these observations are also overviewed. The strategic aim of the present review was to identify and evaluate prospective avenues for analysing dental tissues and developing treatments and prophylaxis for improved dental health.
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Affiliation(s)
- Cyril Besnard
- MBLEM, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, Oxfordshire, UK
| | - Ali Marie
- MBLEM, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, Oxfordshire, UK
| | - Sisini Sasidharan
- MBLEM, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, Oxfordshire, UK
| | - Robert A. Harper
- School of Dentistry, University of Birmingham, 5 Mill Pool Way, Edgbaston, Birmingham B5 7EG, West Midlands, UK
| | - Richard M. Shelton
- School of Dentistry, University of Birmingham, 5 Mill Pool Way, Edgbaston, Birmingham B5 7EG, West Midlands, UK
| | - Gabriel Landini
- School of Dentistry, University of Birmingham, 5 Mill Pool Way, Edgbaston, Birmingham B5 7EG, West Midlands, UK
| | - Alexander M. Korsunsky
- MBLEM, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, Oxfordshire, UK
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2
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Longo S, Corsaro C, Granata F, Fazio E. Clinical CT densitometry for wooden cultural heritage analysis validated by FTIR and Raman spectroscopies. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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3
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Liang J, Levina A, Jia J, Kappen P, Glover C, Johannessen B, Lay PA. Reactivity and Transformation of Antimetastatic and Cytotoxic Rhodium(III)–Dimethyl Sulfoxide Complexes in Biological Fluids: An XAS Speciation Study. Inorg Chem 2019; 58:4880-4893. [DOI: 10.1021/acs.inorgchem.8b03477] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Jun Liang
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Aviva Levina
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Junteng Jia
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Peter Kappen
- Australian Synchrotron, ANSTO, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Chris Glover
- Australian Synchrotron, ANSTO, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Bernt Johannessen
- Australian Synchrotron, ANSTO, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Peter A. Lay
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
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4
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Lee J, Wen B, Carter EA, Combes V, Grau GER, Lay PA. Infrared spectroscopic characterization of monocytic microvesicles (microparticles) released upon lipopolysaccharide stimulation. FASEB J 2017; 31:2817-2827. [PMID: 28314769 DOI: 10.1096/fj.201601272r] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 02/26/2017] [Indexed: 12/28/2022]
Abstract
Microvesicles (MVs) are involved in cell-cell interactions, including disease pathogenesis. Nondestructive Fourier-transform infrared (FTIR) spectra from MVs were assessed as a technique to provide new biochemical insights into a LPS-induced monocyte model of septic shock. FTIR spectroscopy provided a quick method to investigate relative differences in biomolecular content of different MV populations that was complementary to traditional semiquantitative omics approaches, with which it is difficult to provide information on relative changes between classes (proteins, lipids, nucleic acids, carbohydrates) or protein conformations. Time-dependent changes were detected in biomolecular contents of MVs and in the monocytes from which they were released. Differences in phosphatidylcholine and phosphatidylserine contents were observed in MVs released under stimulation, and higher relative concentrations of RNA and α-helical structured proteins were present in stimulated MVs compared with MVs from resting cells. FTIR spectra of stimulated monocytes displayed changes that were consistent with those observed in the corresponding MVs they released. LPS-stimulated monocytes had reduced concentrations of nucleic acids, α-helical structured proteins, and phosphatidylcholine compared with resting monocytes but had an increase in total lipids. FTIR spectra of MV biomolecular content will be important in shedding new light on the mechanisms of MVs and the different roles they play in physiology and disease pathogenesis.-Lee, J., Wen, B., Carter, E. A., Combes, V., Grau, G. E. R., Lay, P. A. Infrared spectroscopic characterization of monocytic microvesicles (microparticles) released upon lipopolysaccharide stimulation.
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Affiliation(s)
- Joonsup Lee
- School of Chemistry and Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales, Australia
| | - Beryl Wen
- Vascular Immunopathology Unit, Bosch Institute-School of Medical Sciences, and
| | - Elizabeth A Carter
- School of Chemistry and Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales, Australia
| | - Valery Combes
- Vascular Immunopathology Unit, Bosch Institute-School of Medical Sciences, and.,Faculty of Science, School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Georges E R Grau
- Vascular Immunopathology Unit, Bosch Institute-School of Medical Sciences, and.,Australian Institute of Nanoscale Science and Technology (AINST), The University of Sydney, Sydney, New South Wales, Australia
| | - Peter A Lay
- School of Chemistry and Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales, Australia; .,Australian Institute of Nanoscale Science and Technology (AINST), The University of Sydney, Sydney, New South Wales, Australia
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5
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Bunaciu AA, Hoang VD, Aboul-Enein HY. Vibrational Micro-Spectroscopy of Human Tissues Analysis: Review. Crit Rev Anal Chem 2016; 47:194-203. [PMID: 27786540 DOI: 10.1080/10408347.2016.1253454] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Vibrational spectroscopy (Infrared (IR) and Raman) and, in particular, micro-spectroscopy and micro-spectroscopic imaging have been used to characterize developmental changes in tissues, to monitor these changes in cell cultures and to detect disease and drug-induced modifications. The conventional methods for biochemical and histophatological tissue characterization necessitate complex and "time-consuming" sample manipulations and the results are rarely quantifiable. The spectroscopy of molecular vibrations using mid-IR or Raman techniques has been applied to samples of human tissue. This article reviews the application of these vibrational spectroscopic techniques for analysis of biological tissue published between 2005 and 2015.
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Affiliation(s)
- Andrei A Bunaciu
- a SCIENT-Research Center for Instrumental Analysis , Tancabesti-Snagov , Romania
| | - Vu Dang Hoang
- b Department of Analytical Chemistry and Toxicology , Hanoi University of Pharmacy , Hanoi , Vietnam
| | - Hassan Y Aboul-Enein
- c Pharmaceutical and Medicinal Chemistry Department , Pharmaceutical and Drug Industries Research Division , Egypt
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6
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Austin C, Smith TM, Farahani RMZ, Hinde K, Carter EA, Lee J, Lay PA, Kennedy BJ, Sarrafpour B, Wright RJ, Wright RO, Arora M. Uncovering system-specific stress signatures in primate teeth with multimodal imaging. Sci Rep 2016; 6:18802. [PMID: 26727334 PMCID: PMC4698674 DOI: 10.1038/srep18802] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 11/25/2015] [Indexed: 11/26/2022] Open
Abstract
Early life stress can disrupt development and negatively impact long-term health trajectories. Reconstructing histories of early life exposure to external stressors is hampered by the absence of retrospective time-specific biomarkers. Defects in tooth enamel have been used to reconstruct stress but the methods used are subjective and do not identify the specific biological systems impacted by external stressors. Here we show that external physical and social stressors impart biochemical signatures in primate teeth that can be retrieved to objectively reconstruct the timing of early life developmental disruptions. Using teeth from captive macaques, we uncovered elemental imprints specific to disruptions of skeletal growth, including major disruptions in body weight trajectory and moderate to severe illnesses. Discrete increases in heat shock protein-70 expression in dentine coincided with elemental signatures, confirming that elemental signals were associated with activation of stress-related pathways. To overcome limitations of conventional light-microscopic analysis, we used high resolution Raman microspectral imaging to identify structural and compositional alterations in enamel and dentine that coincided with elemental signatures and with detailed medical and behavioural data. Integrating these objective biochemical markers with temporal mapping of teeth enables the retrospective study of early life developmental disruptions and their ensuing health sequelae.
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Affiliation(s)
- Christine Austin
- Senator Frank R. Lautenberg Environmental Health Sciences Laboratory, Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA.,Faculty of Dentistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Tanya M Smith
- Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Ramin M Z Farahani
- Faculty of Dentistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Katie Hinde
- Department of Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.,School of Human Evolution and Social Change, Center for Evolution and Medicine, Arizona State University, Arizona, 85287, USA.,California National Primate Research Center, Davis, California 95616, USA
| | - Elizabeth A Carter
- Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales 2006, Australia.,School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Joonsup Lee
- Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales 2006, Australia.,School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Peter A Lay
- Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales 2006, Australia.,School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Brendan J Kennedy
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Babak Sarrafpour
- Senator Frank R. Lautenberg Environmental Health Sciences Laboratory, Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Rosalind J Wright
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Robert O Wright
- Senator Frank R. Lautenberg Environmental Health Sciences Laboratory, Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Manish Arora
- Senator Frank R. Lautenberg Environmental Health Sciences Laboratory, Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA.,Faculty of Dentistry, The University of Sydney, Sydney, New South Wales 2006, Australia
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7
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Hackett MJ, Aitken JB, El-Assaad F, McQuillan JA, Carter EA, Ball HJ, Tobin MJ, Paterson D, de Jonge MD, Siegele R, Cohen DD, Vogt S, Grau GE, Hunt NH, Lay PA. Mechanisms of murine cerebral malaria: Multimodal imaging of altered cerebral metabolism and protein oxidation at hemorrhage sites. SCIENCE ADVANCES 2015; 1:e1500911. [PMID: 26824064 PMCID: PMC4730848 DOI: 10.1126/sciadv.1500911] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 11/03/2015] [Indexed: 06/05/2023]
Abstract
Using a multimodal biospectroscopic approach, we settle several long-standing controversies over the molecular mechanisms that lead to brain damage in cerebral malaria, which is a major health concern in developing countries because of high levels of mortality and permanent brain damage. Our results provide the first conclusive evidence that important components of the pathology of cerebral malaria include peroxidative stress and protein oxidation within cerebellar gray matter, which are colocalized with elevated nonheme iron at the site of microhemorrhage. Such information could not be obtained previously from routine imaging methods, such as electron microscopy, fluorescence, and optical microscopy in combination with immunocytochemistry, or from bulk assays, where the level of spatial information is restricted to the minimum size of tissue that can be dissected. We describe the novel combination of chemical probe-free, multimodal imaging to quantify molecular markers of disturbed energy metabolism and peroxidative stress, which were used to provide new insights into understanding the pathogenesis of cerebral malaria. In addition to these mechanistic insights, the approach described acts as a template for the future use of multimodal biospectroscopy for understanding the molecular processes involved in a range of clinically important acute and chronic (neurodegenerative) brain diseases to improve treatment strategies.
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Affiliation(s)
- Mark J. Hackett
- School of Chemistry and Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Jade B. Aitken
- School of Chemistry and Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Fatima El-Assaad
- Vascular Immunology Unit, Bosch Institute and School of Medical Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - James A. McQuillan
- Molecular Immunopathology Unit, Bosch Institute and School of Medical Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Elizabeth A. Carter
- School of Chemistry and Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Helen J. Ball
- Molecular Immunopathology Unit, Bosch Institute and School of Medical Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Mark J. Tobin
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - David Paterson
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Martin D. de Jonge
- Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Rainer Siegele
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
| | - David D. Cohen
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
| | - Stefan Vogt
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Georges E. Grau
- Vascular Immunology Unit, Bosch Institute and School of Medical Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Nicholas H. Hunt
- Molecular Immunopathology Unit, Bosch Institute and School of Medical Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Peter A. Lay
- School of Chemistry and Vibrational Spectroscopy Core Facility, The University of Sydney, Sydney, New South Wales 2006, Australia
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8
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Locus ceruleus neurons in people with autism contain no histochemically-detectable mercury. Biometals 2015; 29:171-5. [PMID: 26613607 PMCID: PMC4735248 DOI: 10.1007/s10534-015-9898-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 11/21/2015] [Indexed: 01/11/2023]
Abstract
Exposure to environmental mercury has been proposed to play a part in autism. Mercury is selectively taken up by the human locus ceruleus, a region of the brain that has been implicated in autism. We therefore looked for the presence of mercury in the locus ceruleus of people who had autism, using the histochemical technique of autometallography which can detect nanogram amounts of mercury in tissues. In addition, we sought evidence of damage to locus ceruleus neurons in autism by immunostaining for hyperphosphorylated tau. No mercury was found in any neurons of the locus ceruleus of 6 individuals with autism (5 male, 1 female, age range 16–48 years). Mercury was present in locus ceruleus neurons in 7 of 11 (64 %) age-matched control individuals who did not have autism, which is significantly more than in individuals with autism. No increase in numbers of locus ceruleus neurons containing hyperphosphorylated tau was detected in people with autism. In conclusion, most people with autism have not been exposed early in life to quantities of mercury large enough to be found later in adult locus ceruleus neurons. Human locus ceruleus neurons are sensitive indicators of mercury exposure, and mercury appears to remain in these neurons indefinitely, so these findings do not support the hypothesis that mercury neurotoxicity plays a role in autism.
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9
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Pushie MJ, Pickering I, Korbas M, Hackett MJ, George GN. Elemental and chemically specific X-ray fluorescence imaging of biological systems. Chem Rev 2014; 114:8499-541. [PMID: 25102317 PMCID: PMC4160287 DOI: 10.1021/cr4007297] [Citation(s) in RCA: 174] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Indexed: 12/13/2022]
Affiliation(s)
- M. Jake Pushie
- Molecular
and Environmental Sciences Research Group, Department of Geological
Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Ingrid
J. Pickering
- Molecular
and Environmental Sciences Research Group, Department of Geological
Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
- Toxicology
Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada
- Department
of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada
| | - Malgorzata Korbas
- Canadian
Light Source Inc., 44
Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada
- Department
of Anatomy and Cell Biology, University
of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Mark J. Hackett
- Molecular
and Environmental Sciences Research Group, Department of Geological
Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Graham N. George
- Molecular
and Environmental Sciences Research Group, Department of Geological
Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
- Toxicology
Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada
- Department
of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada
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10
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Abstract
Chromium is ubiquitous in the environment as Cr(III) and Cr(VI) oxidation states, which interconvert under environmentally and biologically relevant conditions (although Cr(III) usually predominates). While Cr(VI) is an established human carcinogen and a major occupational and environmental hazard, Cr(III) has long been regarded as an essential human micronutrient, although recent literature has cast serious doubts on the validity of this postulate. Despite five decades of research, no functional Cr-containing enzymes or cofactors have been characterized conclusively, and several hypotheses on their possible structures have been refuted. Gastrointestinal absorption pathways for both Cr(III) and Cr(VI) are apparent and whole-blood speciation can involve Cr(VI) uptake and reduction by red blood cells, as well as Cr(III) binding to both proteins and low-molecular-mass ligands in the plasma. DNA-damaging effects of Cr(VI) and anti-diabetic activities of Cr(III) are likely to arise from common mechanistic pathways that involve reactive Cr(VI/V/IV) intermediates and kinetically inert Cr(III)-protein and Cr(III)-DNA adducts. Both Cr(III) and Cr(VI) are toxic to plants and microorganisms, particularly Cr(VI) due to its higher bioavailability and redox chemistry. Some bacteria reduce Cr(VI) to Cr(III) without the formation of toxic Cr(V) intermediates and these bacteria are being considered for use in the bioremediation of Cr(VI)-polluted environments.
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Affiliation(s)
- Peter A. Lay
- School of Chemistry, The University of Sydney Sydney NSW 2006 Australia
| | - Aviva Levina
- School of Chemistry, The University of Sydney Sydney NSW 2006 Australia
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11
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The Fe-heme structure of met-indoleamine 2,3-dioxygenase-2 determined by X-ray absorption fine structure. Biochem Biophys Res Commun 2014; 450:25-9. [DOI: 10.1016/j.bbrc.2014.05.054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 05/14/2014] [Indexed: 01/20/2023]
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12
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Kong SMY, Chan BKK, Park JS, Hill KJ, Aitken JB, Cottle L, Farghaian H, Cole AR, Lay PA, Sue CM, Cooper AA. Parkinson's disease-linked human PARK9/ATP13A2 maintains zinc homeostasis and promotes α-Synuclein externalization via exosomes. Hum Mol Genet 2014; 23:2816-33. [PMID: 24603074 DOI: 10.1093/hmg/ddu099] [Citation(s) in RCA: 180] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
α-Synuclein plays a central causative role in Parkinson's disease (PD). Increased expression of the P-type ATPase ion pump PARK9/ATP13A2 suppresses α-Synuclein toxicity in primary neurons. Our data indicate that ATP13A2 encodes a zinc pump; neurospheres from a compound heterozygous ATP13A2(-/-) patient and ATP13A2 knockdown cells are sensitive to zinc, whereas ATP13A2 over-expression in primary neurons confers zinc resistance. Reduced ATP13A2 expression significantly decreased vesicular zinc levels, indicating ATP13A2 facilitates transport of zinc into membrane-bound compartments or vesicles. Endogenous ATP13A2 localized to multi-vesicular bodies (MVBs), a late endosomal compartment located at the convergence point of the endosomal and autophagic pathways. Dysfunction in MVBs can cause a range of detrimental effects including lysosomal dysfunction and impaired delivery of endocytosed proteins/autophagy cargo to the lysosome, both of which have been observed in cells with reduced ATP13A2 function. MVBs also serve as the source of intra-luminal nanovesicles released extracellularly as exosomes that can contain a range of cargoes including α-Synuclein. Elevated ATP13A2 expression reduced intracellular α-Synuclein levels and increased α-Synuclein externalization in exosomes >3-fold whereas ATP13A2 knockdown decreased α-Synuclein externalization. An increased export of exosome-associated α-Synuclein may explain why surviving neurons of the substantia nigra pars compacta in sporadic PD patients were observed to over-express ATP13A2. We propose ATP13A2's modulation of zinc levels in MVBs can regulate the biogenesis of exosomes capable of containing α-Synuclein. Our data indicate that ATP13A2 is the first PD-associated gene involved in exosome biogenesis and indicates a potential neuroprotective role of exosomes in PD.
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Affiliation(s)
- Stephanie M Y Kong
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales 2010, Australia
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13
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Antony S, Aitken JB, Vogt S, Lai B, Brown T, Spiccia L, Harris HH. X-ray fluorescence imaging of single human cancer cells reveals that the N-heterocyclic ligands of iodinated analogues of ruthenium anticancer drugs remain coordinated after cellular uptake. J Biol Inorg Chem 2013; 18:845-53. [PMID: 23943098 DOI: 10.1007/s00775-013-1027-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 07/14/2013] [Indexed: 01/04/2023]
Abstract
Analogues of KP1019 containing iodinated indazole ligands were prepared to investigate the biological fate of the Ru-N-heterocycle bond in this class of anticancer agents. The new complexes, 5-iodoindazolium trans-tetrachloridobis(5-iodoindazole)ruthen(III)ate (1) and 5-iodoindazolium trans-tetrachlorido(dimethyl sulfoxide)(5-iodoindazole)ruthen(III)ate (3), were characterized by elemental analysis, mass spectrometry and UV-vis spectrophotometry. Tetramethylammonium salts of these complexes (2 and 4) were synthesized and characterized in a similar manner. Half-maximum inhibitory concentrations of 2 and 4 with regard to A549 cells at 24 h were determined on the basis of the dose-response curves derived from real-time cell adhesion impedance measurements and were shown to be in the same range as those determined for KP1019 and NAMI-A using the same method. X-ray fluorescence imaging of single cultured A549 cells treated with 2 or 4 showed that, in both cases, the distribution of ruthenium and iodine was identical, indicating that the Ru-N bonds in the anionic complexes remained intact after incubation in culture medium and subsequent cellular uptake and processing.
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Affiliation(s)
- Sumy Antony
- School of Chemistry and Physics, The University of Adelaide, Adelaide, SA, 5005, Australia
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14
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Aitken JB, Shearer EL, Giles NM, Lai B, Vogt S, Reboucas JS, Batinic-Haberle I, Lay PA, Giles GI. Intracellular Targeting and Pharmacological Activity of the Superoxide Dismutase Mimics MnTE-2-PyP5+ and MnTnHex-2-PyP5+ Regulated by Their Porphyrin Ring Substituents. Inorg Chem 2013; 52:4121-3. [DOI: 10.1021/ic300700g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jade B. Aitken
- School of
Chemistry, The University of Sydney, NSW
2006, Australia
| | - Emily L. Shearer
- Department
of Pharmacology and Toxicology, University of Otago, P.O. Box 913, Dunedin, New Zealand
| | - Niroshini M. Giles
- Department
of Pharmacology and Toxicology, University of Otago, P.O. Box 913, Dunedin, New Zealand
| | - Barry Lai
- X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Stefan Vogt
- X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Julio S. Reboucas
- Departamento de Quimica, Universidade Federal da Paraiba, Joao Pessoa, PB, Brazil
| | - Ines Batinic-Haberle
- Department of Radiation Oncology, Duke University, Durham, North Carolina 27710, United
States
| | - Peter A. Lay
- School of
Chemistry, The University of Sydney, NSW
2006, Australia
| | - Gregory I. Giles
- Department
of Pharmacology and Toxicology, University of Otago, P.O. Box 913, Dunedin, New Zealand
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15
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Hackett MJ, Lee J, El-Assaad F, McQuillan JA, Carter EA, Grau GE, Hunt NH, Lay PA. FTIR imaging of brain tissue reveals crystalline creatine deposits are an ex vivo marker of localized ischemia during murine cerebral malaria: general implications for disease neurochemistry. ACS Chem Neurosci 2012; 3:1017-24. [PMID: 23259037 DOI: 10.1021/cn300093g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 09/11/2012] [Indexed: 12/13/2022] Open
Abstract
Phosphocreatine is a major cellular source of high energy phosphates, which is crucial to maintain cell viability under conditions of impaired metabolic states, such as decreased oxygen and energy availability (i.e., ischemia). Many methods exist for the bulk analysis of phosphocreatine and its dephosphorylated product creatine; however, no method exists to image the distribution of creatine or phosphocreatine at the cellular level. In this study, Fourier transform infrared (FTIR) spectroscopic imaging has revealed the ex vivo development of creatine microdeposits in situ in the brain region most affected by the disease, the cerebellum of cerebral malaria (CM) diseased mice; however, such deposits were also observed at significantly lower levels in the brains of control mice and mice with severe malaria. In addition, the number of deposits was observed to increase in a time-dependent manner during dehydration post tissue cutting. This challenges the hypotheses in recent reports of FTIR spectroscopic imaging where creatine microdeposits found in situ within thin sections from epileptic, Alzheimer's (AD), and amlyoid lateral sclerosis (ALS) diseased brains were proposed to be disease specific markers and/or postulated to contribute to the brain pathogenesis. As such, a detailed investigation was undertaken, which has established that the creatine microdeposits exist as the highly soluble HCl salt or zwitterion and are an ex-vivo tissue processing artifact and, hence, have no effect on disease pathogenesis. They occur as a result of creatine crystallization during dehydration (i.e., air-drying) of thin sections of brain tissue. As ischemia and decreased aerobic (oxidative metabolism) are common to many brain disorders, regions of elevated creatine-to-phosphocreatine ratio are likely to promote crystal formation during tissue dehydration (due to the lower water solubility of creatine relative to phosphocreatine). The results of this study have demonstrated that although the deposits do not occur in vivo, and do not directly play any role in disease pathogenesis, increased levels of creatine deposits within air-dried tissue sections serve as a highly valuable marker for the identification of tissue regions with an altered metabolic status. In this study, the location of crystalline creatine deposits were used to identify whether an altered metabolic state exists within the molecular and granular layers of the cerebellum during CM, which complements the recent discovery of decreased oxygen availability in the brain during this disease.
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Affiliation(s)
- Mark J. Hackett
- School of Chemistry, The University of Sydney, NSW 2006, Australia
| | - Joonsup Lee
- School of Chemistry, The University of Sydney, NSW 2006, Australia
| | | | | | | | | | | | - Peter A. Lay
- School of Chemistry, The University of Sydney, NSW 2006, Australia
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16
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George GN, Pickering IJ, Pushie MJ, Nienaber K, Hackett MJ, Ascone I, Hedman B, Hodgson KO, Aitken JB, Levina A, Glover C, Lay PA. X-ray-induced photo-chemistry and X-ray absorption spectroscopy of biological samples. JOURNAL OF SYNCHROTRON RADIATION 2012; 19:875-86. [PMID: 23093745 PMCID: PMC3480274 DOI: 10.1107/s090904951203943x] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 09/16/2012] [Indexed: 05/03/2023]
Abstract
As synchrotron light sources and optics deliver greater photon flux on samples, X-ray-induced photo-chemistry is increasingly encountered in X-ray absorption spectroscopy (XAS) experiments. The resulting problems are particularly pronounced for biological XAS experiments. This is because biological samples are very often quite dilute and therefore require signal averaging to achieve adequate signal-to-noise ratios, with correspondingly greater exposures to the X-ray beam. This paper reviews the origins of photo-reduction and photo-oxidation, the impact that they can have on active site structure, and the methods that can be used to provide relief from X-ray-induced photo-chemical artifacts.
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Affiliation(s)
- Graham N. George
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2
| | - Ingrid J. Pickering
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2
| | - M. Jake Pushie
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2
| | - Kurt Nienaber
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2
| | - Mark J. Hackett
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E2
| | - Isabella Ascone
- ENSCP Chimie ParisTech, LCF, CNRS, UMR 7223, 75005 Paris, France
| | - Britt Hedman
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Keith O. Hodgson
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Jade B. Aitken
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
- Australian Synchrotron, Clayton, VIC 3168, Australia
- Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801, Japan
| | - Aviva Levina
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | | | - Peter A. Lay
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
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17
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Biological applications of synchrotron radiation infrared spectromicroscopy. Biotechnol Adv 2012; 30:1390-404. [PMID: 22401782 DOI: 10.1016/j.biotechadv.2012.02.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 02/20/2012] [Indexed: 11/24/2022]
Abstract
Extremely brilliant infrared (IR) beams provided by synchrotron radiation sources are now routinely used in many facilities with available commercial spectrometers coupled to IR microscopes. Using these intense non-thermal sources, a brilliance two or three order of magnitude higher than a conventional source is achievable through small pinholes (<10 μm) with a high signal to-noise ratio. IR spectroscopy is a powerful technique to investigate biological systems and offers many new imaging opportunities. The field of infrared biological imaging covers a wide range of fundamental issues and applied researches such as cell imaging or tissue imaging. Molecular maps with a spatial resolution down to the diffraction limit may be now obtained with a synchrotron radiation IR source also on thick samples. Moreover, changes of the protein structure are detectable in an IR spectrum and cellular molecular markers can be identified and used to recognize a pathological status of a tissue. Molecular structure and functions are strongly correlated and this aspect is particularly relevant for imaging. We will show that the brilliance of synchrotron radiation IR sources may enhance the sensitivity of a molecular signal obtained from small biosamples, e.g., a single cell, containing extremely small amounts of organic matter. We will also show that SR IR sources allow to study chemical composition and to identify the distribution of organic molecules in cells at submicron resolution is possible with a high signal-to-noise ratio. Moreover, the recent availability of two-dimensional IR detectors promises to push forward imaging capabilities in the time domain. Indeed, with a high current synchrotron radiation facility and a Focal Plane Array the chemical imaging of individual cells can be obtained in a few minutes. Within this framework important results are expected in the next years using synchrotron radiation and Free Electron Laser (FEL) sources for spectro-microscopy and spectral-imaging, alone or in combination with Scanning Near-field Optical Microscopy methods to study the molecular composition and dynamic changes in samples of biomedical interest at micrometric and submicrometric scales, respectively.
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18
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Synchrotron radiation induced X-ray emission studies of the antioxidant mechanism of the organoselenium drug ebselen. J Biol Inorg Chem 2012; 17:589-98. [DOI: 10.1007/s00775-012-0879-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 01/23/2012] [Indexed: 01/30/2023]
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19
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Dillon CT. Synchrotron Radiation Spectroscopic Techniques as Tools for the Medicinal Chemist: Microprobe X-Ray Fluorescence Imaging, X-Ray Absorption Spectroscopy, and Infrared Microspectroscopy. Aust J Chem 2012. [DOI: 10.1071/ch11287] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
This review updates the recent advances and applications of three prominent synchrotron radiation techniques, microprobe X-ray fluorescence spectroscopy/imaging, X-ray absorption spectroscopy, and infrared microspectroscopy, and highlights how these tools are useful to the medicinal chemist. A brief description of the principles of the techniques is given with emphasis on the advantages of using synchrotron radiation-based instrumentation rather than instruments using typical laboratory radiation sources. This review focuses on several recent applications of these techniques to solve inorganic medicinal chemistry problems, focusing on studies of cellular uptake, distribution, and biotransformation of established and potential therapeutic agents. The importance of using these synchrotron-based techniques to assist the development of, or validate the chemistry behind, drug design is discussed.
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Aitken JB, Antony S, Weekley CM, Lai B, Spiccia L, Harris HH. Distinct cellular fates for KP1019 and NAMI-A determined by X-ray fluorescence imaging of single cells. Metallomics 2012; 4:1051-6, 1007. [DOI: 10.1039/c2mt20072d] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Abstract
The current status and likely future directions of complexes of V(V/IV), Cr(III), Mo(VI), W(VI), Zn(II), Cu(II), and Mn(III) as potential oral drugs against type 2 diabetes are reviewed. We propose a unified model of extra- and intracellular mechanisms of anti-diabetic efficacies of V(V/IV), Mo(VI), W(VI), and Cr(III), centred on high-oxidation-state oxido/peroxido species that inhibit protein tyrosine phosphatases (PTPs) involved in insulin signalling. The postulated oxidative mechanism of anti-diabetic activity of Cr(III) via carcinogenic Cr(VI/V) (which adds to safety concerns) is consistent with recent clinical trials on Cr(III) picolinate, where activity was apparent only in patients with poorly controlled diabetes (high oxidative stress), and the correlation between the anti-diabetic activities and ease of oxidation of Cr(III) supplements and their metabolites in vivo. Zn(II) and Cu(II) anti-diabetics act via different mechanisms and are unlikely to be used as specific anti-diabetics due to their diverse and unpredictable biological activities. Hence, future research directions are likely to centre on enhancing the bioavailability and selectivity of V(V/IV), Mo(VI), or W(VI) drugs. The strategy of potentiating circulating insulin with metal ions has distinct therapeutic advantages over interventions that stimulate the release of more insulin, or use insulin mimetics, because of many adverse side-effects of increased levels of insulin, including increased risks of cancer and cardiovascular diseases.
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Affiliation(s)
- Aviva Levina
- School of Chemistry, The University of Sydney, NSW, Australia
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22
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Dokken KM, Davis LC. Infrared monitoring of dinitrotoluenes in sunflower and maize roots. JOURNAL OF ENVIRONMENTAL QUALITY 2011; 40:719-30. [PMID: 21546658 DOI: 10.2134/jeq2010.0143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Infrared microspectroscopy (IMS) is emerging as an important analytical tool for the structural analysis of biological tissue. This report describes the use of IMS coupled to a synchrotron source combined with principal components analysis (PCA) to monitor the fate and effect of dinitrotoluenes in the roots of maize and sunflower plants. Infrared imaging revealed that maize roots metabolized 2,4-dinitrotoluene (DNT) and 2,6-DNT. The DNTs and their derivative aromatic amines were predominantly associated with epidermis and xylem. Both isomers of DNT altered the structure and production of pectin and pectic polysaccharides in maize and sunflower plant roots. Infrared peaks diagnostic for aromatic amines were seen at the 5 mg L concentrations for both DNTs in maize and sunflower treated tissue. However, only infrared peaks for nitro groups, not aromatic amines, were present in the maize treated at 10 mg L For sunflower, the 10 mg L level was toxic and also produced very dark root systems making spectra difficult to obtain. Maize and sunflower seem unable to metabolize effectively at concentrations higher than about 5 mg L DNT in hydroponic solution. Based on the results of this study, IMS combined with PCA can be an effective means of determining the fate and metabolism of organic contaminants in plant tissue when isotopically labeled compounds are not available.
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Affiliation(s)
- K M Dokken
- Department of Biochemistry, Kansas State University, Manhattan, KS 66506, USA
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23
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Hackett MJ, McQuillan JA, El-Assaad F, Aitken JB, Levina A, Cohen DD, Siegele R, Carter EA, Grau GE, Hunt NH, Lay PA. Chemical alterations to murine brain tissue induced by formalin fixation: implications for biospectroscopic imaging and mapping studies of disease pathogenesis. Analyst 2011; 136:2941-52. [DOI: 10.1039/c0an00269k] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Finney L, Chishti Y, Khare T, Giometti C, Levina A, Lay PA, Vogt S. Imaging metals in proteins by combining electrophoresis with rapid x-ray fluorescence mapping. ACS Chem Biol 2010; 5:577-87. [PMID: 20392082 DOI: 10.1021/cb1000263] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Growing evidence points toward a very dynamic role for metals in biology. This suggests that physiological circumstance may mandate metal ion redistribution among ligands. This work addresses a critical need for technology that detects, identifies, and measures the metal-containing components of complex biological matrixes. We describe a direct, user-friendly approach for identifying and quantifying metal-protein adducts in complex samples using native- or SDS-PAGE, blotting, and rapid synchrotron X-ray fluorescence mapping with micro-XANES (X-ray absorption near-edge structure) of entire blots. The identification and quantification of each metal bound to a protein spot has been demonstrated, and the technique has been applied in two exemplary cases. In the first, the speciation of the in vitro binding of exogenous chromium to blood serum proteins was influenced markedly by both the oxidation state of chromium exposed to the serum proteins and the treatment conditions, which is of relevance to the biochemistry of Cr dietary supplements. In the second case, in vivo changes in endogenous metal speciation were examined to probe the influence of oxygen depletion on iron speciation in Shewanella oneidensis.
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Affiliation(s)
- Lydia Finney
- Biosciences Division and
- X-ray Sciences Division, Argonne National Laboratory, Argonne, Illinois
| | | | | | | | - Aviva Levina
- School of Chemistry, The University of Sydney, NSW 2006, Australia
| | - Peter A Lay
- School of Chemistry, The University of Sydney, NSW 2006, Australia
| | - Stefan Vogt
- X-ray Sciences Division, Argonne National Laboratory, Argonne, Illinois
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25
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Liu M, Lim ZJ, Gwee YY, Levina A, Lay PA. Characterization of a ruthenium(III)/NAMI-A adduct with bovine serum albumin that exhibits a high anti-metastatic activity. Angew Chem Int Ed Engl 2010; 49:1661-4. [PMID: 20127775 DOI: 10.1002/anie.200906079] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Mimi Liu
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
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Liu M, Lim Z, Gwee Y, Levina A, Lay P. Characterization of a Ruthenium(III)/NAMI-A Adduct with Bovine Serum Albumin that Exhibits a High Anti-Metastatic Activity. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200906079] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Carter EA, Rayner BS, McLeod AI, Wu LE, Marshall CP, Levina A, Aitken JB, Witting PK, Lai B, Cai Z, Vogt S, Lee YC, Chen CI, Tobin MJ, Harris HH, Lay PA. Silicon nitride as a versatile growth substrate for microspectroscopic imaging and mapping of individual cells. MOLECULAR BIOSYSTEMS 2010; 6:1316-22. [DOI: 10.1039/c001499k] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Interest in Ru anticancer drugs has been growing rapidly since NAMI-A ((ImH(+))[Ru(III)Cl(4)(Im)(S-dmso)], where Im = imidazole and S-dmso = S-bound dimethylsulfoxide) or KP1019 ((IndH(+))[Ru(III)Cl(4)(Ind)(2)], where Ind = indazole) have successfully completed phase I clinical trials and an array of other Ru complexes have shown promise for future development. Herein, the recent literature is reviewed critically to ascertain likely mechanisms of action of Ru-based anticancer drugs, with the emphasis on their reactions with biological media. The most likely interactions of Ru complexes are with: (i) albumin and transferrin in blood plasma, the former serving as a Ru depot, and the latter possibly providing active transport of Ru into cells; (ii) collagens of the extracellular matrix and actins on the cell surface, which are likely to be involved in the specific anti-metastatic action of Ru complexes; (iii) regulatory enzymes within the cell membrane and/or in the cytoplasm; and (iv) DNA in the cell nucleus. Some types of Ru complexes can also promote the intracellular formation of free radical species, either through irradiation (photodynamic therapy), or through reactions with cellular reductants. The metabolic pathways involve competition among reduction, aquation, and hydrolysis in the extracellular medium; binding to transport proteins, the extracellular matrix, and cell-surface biomolecules; and diffusion into cells; with the extent to which individual drugs participate in various steps along these pathways being crucial factors in determining whether they are mainly anti-metastatic or cytotoxic. This diversity of modes of action of Ru anticancer drugs is also likely to enhance their anticancer activities and to reduce the potential for them to develop tumour resistance. New approaches to metabolic studies, such as X-ray absorption spectroscopy and X-ray fluorescence microscopy, are required to provide further mechanistic insights, which could lead to the rational design of improved Ru anticancer drugs.
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Affiliation(s)
- Aviva Levina
- School of Chemistry, The University of Sydney, Sydney NSW 2006, Australia
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