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Microprobe XRF Mapping and XAS Investigations of the Intracellular Metabolism of Arsenic for Understanding Arsenic-Induced Toxicity

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journal contribution
posted on 15.09.2008, 00:00 by Kristie L. Munro, Anna Mariana, Andrejs I. Klavins, Amalanie J. Foster, Barry Lai, Stefan Vogt, ZhongHou Cai, Hugh H. Harris, Carolyn T. Dillon
Arsenic (As) is responsible for mass-poisonings worldwide following the ingestion of As-contaminated drinking water. Importantly, however, As toxicity is exploited in the antileukemia drug, Trisenox (As2O3), which successfully cures 65−80% of patients suffering relapsed acute promyelocytic leukemia. In an effort to determine the intracellular organelle and biomolecular targets of As, microprobe X-ray fluorescence (XRF) and X-ray absorption spectroscopy (XAS) analyses were performed on HepG2 cells following their exposure to high doses of arsenite (1 mM) or arsenate (20 mM). Microprobe XRF elemental mapping of thin-sectioned cells showed As accumulation in the euchromatin region of the cell nucleus (following arsenite exposure) synonymous with As targeting of DNA or proteins involved in DNA transcription. X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) analysis of arsenite-treated cells, however, showed the predominance of an As tris-sulfur species, providing increased credence to As interactions with nuclear proteins as a key factor in As-induced toxicity.