PubMed · 13956899
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S ISHIZAWA, Y MORIKAWA. 1962. [Hair and trace elements].. https://pubmed.ncbi.nlm.nih.gov/13956899/
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Chronic inorganic arsenic (iAs) exposure affects > 220 million people worldwide and skin cancer is a hallmark of long-term iAs exposure. Limited information exists regarding arsenic methylation by human keratinocytes and how methylation influences skin carcinogenesis. Inorganic arsenite (iAsIII) and its methylated metabolites disrupt diverse zinc finger proteins, leading to differential toxicity patterns. We examined arsenic methylation capacity in non-malignant human keratinocytes and interrogated proteomic remodeling across three stages of iAsIII induced malignant transformation using the well-established preclinical HaCaT model. Arsenic methylation was assessed by hydride generation cryotrapping inductively coupled-mass spectrometry and global proteomic changes were analyzed by tandem-mass tagging liquid chromatography-tandem mass spectrometry. Primary, hTERT-immortalized and HaCaT human keratinocytes exhibited negligible arsenic methylation, with iAsIII comprising at least 98.5% of total intracellular arsenic, attributable to minimal expression of arsenite methyltransferase. Proteomic profiling identified over 275 differentially expressed proteins at each stage of transformation, including multiple zinc finger proteins implicated in cell cycle control, RNA metabolism, and genome stability. Ingenuity® Pathway Analysis revealed progressive, coordinated disruption of cancer-associated pathways and regulatory networks over the transformation timeline, including zinc-coordinating upstream regulators that may explain widespread pathway dysregulation. Collectively, our findings suggest that iAsIII promotes skin carcinogenesis by disrupting C3H1- and C4-type zinc finger protein-centered regulatory networks that coordinate cancer-associated signaling and metabolic pathways in human keratinocytes, highlighting key candidates for future mechanistic studies.
Total and inorganic As contents of cooked vegetables obtained from an arsenic endemic area of Chile were analyzed. Inorganic As intake from those foods, bread, and water was estimated. The study was performed in two different periods, in which the water used by the population for drinking and cooking purposes contained 0.572 (first period) or 0.041 microg mL(-)(1) (second period). In the first period, the FAO/WHO reference intake was exceeded by all of the persons interviewed. In the second period, the reference intake was exceeded by all of the persons interviewed ages 13-15. The foods studied contributed 4% (first period) or 25% (second period) of the inorganic As intake. The results show the contribution of food to inorganic As intake and the risk to which those ages 15 or younger are exposed.
In this work the quantitative determination and analytical speciation of arsenic were undertaken in different types of nuts, randomly purchased from local markets. The hardness of the whole nuts and high lipid content made the preparation of this material difficult for analysis. The lack of sample homogeneity caused irreproducible results. To improve the precision of analysis, arsenic was determined separately in nut oil and in the defatted sample. The lipids were extracted from the ground sample with the two portions of a mixture of chloroform and methanol (2:1). The defatted material was dried and ground again, yielding a fine powder. The nut oil was obtained by combining the two organic extracts and by evaporating the solvents. The two nut fractions were microwave digested, and total arsenic was determined by inductively coupled plasma mass spectrometry (ICP-MS). The results obtained for oils from different types of nuts showed element concentration in the range 2.9-16.9 ng g(-)(1). Lower levels of arsenic were found in defatted material (<0.1 ng g(-)(1) with the exception of Brazil nuts purchased with and without shells, 3.0 and 2.8 ng g(-)(1) respectively). For speciation analysis of arsenic in nut oils, elemental species were extracted from 2 g of oil with 12 mL of chloroform/methanol (2:1) and 8 mL of deionized water. The aqueous layer, containing polar arsenic species, was evaporated and the residue dissolved and analyzed by ion chromatography-ICP-MS. The anion exchange chromatography enabled separation of As(III), dimethylarsinic acid (DMAs(V)), monomethylarsonic acid (MMAs(V)), and As(V) within 8 min. Several types of nuts were analyzed, including walnuts, Brazil nuts, almonds, cashews, pine nuts, peanuts, pistachio nuts, and sunflower seeds. The recovery for the speciation procedure was in the range 72.7-90.6%. The primary species found in the oil extracts were As(III) and As(V). The arsenic concentration levels in these two species were 0.7-12.7 and 0.5-4.3 ng g(-)(1), respectively. The contribution of As in DMAs(V) ranged from 0.1 +/- 0.1 ng g(-)(1) in walnuts to 1.3 +/- 0.3 ng g(-)(1) in pine nuts. MMAs(V) was not detected in almonds, peanuts, pine nuts, sunflower seeds, or walnuts, and the highest concentration was found in pistachio nuts (0.5 +/- 0.2 ng g(-)(1)).