title: Iron overload of human colon adenocarcinoma cells studied by synchrotron-based X-ray techniques.
abstract: Fast- and slow-proliferating human adenocarcinoma colorectal cells, HT-29 and HCA-7, respectively, overloaded with transferrin (Tf), Fe(III) citrate, Fe(III) chloride and Fe(II) sulfate were studied by synchrotron radiation total-reflection X-ray spectrometry (TXRF), TXRF-X-ray absorption near edge structure (TXRF-XANES), and micro-X-ray fluorescence imaging to obtain information on the intracellular storage of overloaded iron (Fe). The determined TfR1 mRNA expression for the investigated cells correlated with their proliferation rate. In all cases, the Fe XANES of cells overloaded with inorganic Fe was found to be similar to that of deliquescent Fe(III) sulfate characterized by a distorted octahedral geometry. A fitting model using a linear combination of the XANES of Tf and deliquescent Fe(III) sulfate allowed to explain the near edge structure recorded for HT-29 cells indicating that cellular overload with inorganic Fe results in a non-ferritin-like fast Fe storage. Hierarchical cluster analysis of XANES spectra recorded for Fe overloaded HT-29 and HCA-7 cells was able to distinguish between Fe treatments performed with different Fe species with a 95% hit rate, indicating clear differences in the Fe storage system. Micro-X-ray fluorescence imaging of Fe overloaded HT-29 cells revealed that Fe is primarily located in the cytosol of the cells. By characterizing the cellular Fe uptake, Fe/S content ratios were calculated based on the X-ray fluorescence signals of the analytes. These Fe/S ratios were dramatically lower for HCA-7 treated with organic Fe(III) treatments suggesting dissimilarities from the Tf-like Fe uptake.
authors.affiliation: Laboratory of Environmental Chemistry and Bioanalytics, Department of Analytical Chemistry, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter stny 1/A, 1117, Budapest, Hungary.
authors.forename: Victor G
authors.initials: VG
authors.lastname: Mihucz
authors.affiliation: Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands.
authors.forename: Florian
authors.initials: F
authors.lastname: Meirer
authors.affiliation: Laboratory of Environmental Chemistry and Bioanalytics, Department of Analytical Chemistry, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter stny 1/A, 1117, Budapest, Hungary.
authors.forename: Zsófia
authors.initials: Z
authors.lastname: Polgári
authors.affiliation: 2nd Department of Pathology, Semmelweis University, Üllői út 93, 1091, Budapest, Hungary.
authors.forename: Andrea
authors.initials: A
authors.lastname: Réti
authors.affiliation: Micro Nano Analytical Laboratory, Centre for Materials and Microsystems, Fondazione Bruno Kessler, Povo, Via Sommarive 18, 38123, Trento, Italy.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Pepponi
authors.affiliation: Atominstitut, Technische Universitaet Wien, Stadionallee 2, 1020, Vienna, Austria.
authors.forename: Dieter
authors.initials: D
authors.lastname: Ingerle
authors.affiliation: Laboratory of Environmental Chemistry and Bioanalytics, Department of Analytical Chemistry, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter stny 1/A, 1117, Budapest, Hungary. szobosz@chem.elte.hu.
authors.forename: Norbert
authors.initials: N
authors.lastname: Szoboszlai
authors.affiliation: Atominstitut, Technische Universitaet Wien, Stadionallee 2, 1020, Vienna, Austria.
authors.forename: Christina
authors.initials: C
authors.lastname: Streli
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D019190:Iron Overload / Q000378:metabolism*; D017356:Synchrotrons
keywords: Cancer cells; Fe storage; Micro-X-ray imaging; Transferrin