Journal: Metallomics : integrated biometal science
Qualitative and quantitative methods were developed for selenium and sulphur mapping/quantification in sunflower (Helianthus annuus L.) leaves. The plants were grown for 50 days in a greenhouse, being divided into two groups, one irrigated with only deionized water and the other treated with a daily dose of 7.58 mg of Na(2)SeO(3). Leaves were collected during the growth period for directly evaluating the distribution of Se and S in these structures. For quantification analysis, pellets were produced from both CRM (100 and 1575a for Se and S, respectively) and the sunflower materials. The pellets were doped with 25 and 1200 μg g(-1) Se and 5 and 20 mg g(-1) S and analyzed by LA-ICP-MS. For accuracy purposes all the samples were also decomposed via microwave and analyzed by ICP-MS. To avoid polyatomic interferences Se and S were monitored as SeO(+) and SO(+) at m/z 96 and 48, respectively, (12)C(+) was used as an internal standard, and the ratios between SeO(+)/C(+) and SO(+)/C(+) were used for measurements. Statistic tests (t test at 95% confidence level) confirming good agreement between LA-ICP-MS and ICP-MS indicated the accuracy of this technique.
Two reference measurement procedures are presented here that allow the determination of the iron saturation in human transferrin, based on different molecular properties. The results, directly derived from the number of ions bound to the protein molecule, are traceable to the SI. Up to now, the iron saturation has only been deduced indirectly from the amount-of-substance ratio of serum iron to transferrin in serum. Interlaboratory tests have shown the need for more accurate methods, as the results from many participant test samples for both parameters do not lie within the acceptable range of deviation given by relevant guidelines when different methods or kits are applied. Using isotope dilution, an HPLC ICP-MS procedure was developed in compliance with the requirements of a primary reference measurement procedure. In this manner, the iron saturation was measured with an associated relative expanded measurement uncertainty of 4%. Based on the results, a straightforward Raman procedure was evolved, which allows the determination of the iron saturation in transferrin with an associated relative expanded uncertainty of 7%.
Arsenic trioxide (As2O3) has been recently established as one of the most effective drugs for the treatment of patients with acute promyelocytic leukemia. However, it has exhibited to be less efficient for the non-promyelocytic leukaemia or other types of malignant tumors. The purpose of the present study was to explore new therapeutic strategies based on As2O3 for human multiple myeloma. Here, we first report cryptotanshinone (CPT) and As2O3 synergy for enhanced cytotoxicity in human multiple myeloma U266 cells. In particular, the apoptosis related proteins (e.g., cleaved poly (ADP-ribose) polymerase (PARP), caspase-3 and -9) were significantly increased by the combination treatment (iAs(III) + CPT), whereas, the expression of survival proteins such as Bcl-2 and survivin was suppressed, suggesting that the induction of apoptosis through mitochondrial-mediated apoptotic pathway. In addition, there were no appreciable effects observed in cells after exposure to either As2O3 or CPT alone. In order to better understand the molecular mechanism, we further determined the phosphorylation of STAT3, JNK, ERK and p38. Interestingly, phosphorylation of JNK and p38 were remarkably induced by combination treatment, and no significant inhibition of STAT3 or ERK was observed. In addition, induction of apoptosis in human multiple myeloma cells was partially abrogated only by pretreatment with JNK inhibitor and not by p38 inhibitor, suggesting that JNK pathway may play an important role in induction of apoptosis by the combination of iAs(III) and CPT. Further studies are needed to evaluate this synergistic anticancer effect in vivo. In the near future, this new approach might be used clinically for multiple myeloma (MM) treatment.
The mechanism by which the most relevant ruthenium anticancer drugs are activated in tumors to commence their tumor-inhibiting action remains one of the challenging research tasks of present-day metallomics. This contribution aims to capture and identify eventually more reactive species of one of two bis-indazole tetrachloridoruthenate(iii) compounds that are progressing in clinical trials. In view of the fact that the transport of ruthenium into cancer cells is governed by transferrin receptors, the susceptibility of the Ru drug adduct with holo-transferrin to exposure by glutathione and ascorbic acid (at their cancer cytosol concentrations) was studied by inductively coupled plasma mass spectrometry (ICP-MS), following isolation of the reaction products by ultrafiltration. Next, capillary electrophoresis coupled to ICP-MS was applied to monitor changes in the Ru speciation both under simulated cancer cytosol conditions and in real cytosol and to assign the charge state of novel metal species. The latter were identified by using tandem electrospray ionization MS in the respective ion mode. The formation of ruthenium(ii) species was for the first time revealed, in which the central metal is coordinated by the reduced (GSH) or the oxidized (GSSG) form of glutathione, i.e. [Ru(II)HindCl4(GSH)](2-) and [Ru(II)HindCl4(GSSG)](2-), respectively (Hind = indazole). Ascorbic acid released the ruthenium functionality from the protein-bound form in a different way, the products of adduct cleavage containing aqua ligands. Distribution of low-molecular mass species of Ru in human cytosol was found to have very much in common with the ruthenium speciation assayed under simulated cytosol conditions.
Obtaining the knowledge of the “omics” and therefore of the metallomics of gestational diabetes mellitus (GDM) appears to be a necessary task to obtain information about the molecular causes of this disease. In this study, the metallome of GDM and of other types of diabetes mellitus was first reviewed. The comparative analysis of the published data revealed that no GDM elemental markers could be identified with sufficient reliability in blood or in the other considered samples, with the partial exception of selenium. The placenta was chosen as an alternative target organ for the analysis of the GDM metallome. The full elemental average composition of 19 healthy placentas was obtained by ICP-MS. Analyses were then performed on 28 placentas from women affected by GDM. The statistical tests and the principal component analysis evidenced that cadmium was found in lower concentrations and selenium was found in higher concentrations in GDM placentas than in those of the control group. These results were interpreted in light of literature data, and they attract attention on two key elements for understanding the molecular pathways of GDM.
The oxidative stress that evolves under cobalt and nickel exposure is thought to exert toxicity, though the exact routes of such metal poisoning remain ambiguous. We revisited the metal toxicity in Escherichia coli to show that cobalt and nickel exposure at levels as low as 0.5 and 1 mM, respectively, visibly inhibits growth. We also observed that acidic conditions aggravated, while alkaline conditions alleviated the metal toxicity. Besides, 1 mM manganese, which is non-cytotoxic, as judged by the growth of E. coli, synergistically elevated cobalt and nickel stress. However, the metal toxicity did not lead to oxidative stress in E. coli. On the other hand, we show that cobalt and nickel, but not manganese, reduced the rate of DNA replication to 50% within 2 hours. Interestingly, the metal ions promoted DNA double-strand breaks but did not induce SOS repair pathways, indicating that the metal ions could block SOS induction. To test this, we show that cobalt and nickel, but not manganese, suppressed the nalidixic acid-induced SOS response. Finally, using an in vitro assay system, we demonstrated that cobalt and nickel inhibit RecBCD function, which is essential for SOS induction. Therefore, our data indicate that cobalt and nickel affect DNA replication, damage DNA, and inhibit the SOS repair pathway to exert toxicity.
The transferrin receptor (TfR1), which mediates cellular iron uptake through clathrin-dependent endocytosis of iron-loaded transferrin, plays a key role in iron homeostasis. Since the number of TfR1 molecules at the cell surface is the rate-limiting step for iron entry into cells and is essential to prevent iron overload, TfR1 expression is precisely controlled at multiple levels. In this review, we have discussed the latest advances in the molecular regulation of TfR1 expression and we have considered current understanding of TfR1 function beyond its canonical role in providing iron for erythroid precursors and rapidly proliferating cells.
Aluminum (Al) is the most abundant metal element in the earth’s crust, and is implicated in the pathogenesis of liver lesions. However, the mechanisms underlying Al3+-induced hepatotoxicity are still largely elusive. Based on analysis with native gel electrophoresis, Al3+ plus 8-hydroxyquinoline staining and LC-MS/MS, the proteins with high Al3+ affinity were identified to be carbamoyl-phosphate synthase, adenosylhomocysteinase, heat shock protein 90-alpha, carbonic anhydrase 3, serum albumin and calreticulin. These proteins are involved in physiological processes such as the urea cycle, redox reactions, apoptosis and so on. Then we established an Al3+-treated rat model for biochemical tests, morphology observation and Ca2+ homeostasis analysis, in order to evaluate the extent of oxidative damage, hepatic histopathology and specific indicators of Al3+-related proteins in liver. Our findings indicated the high-affinity interactions with Al3+ perturbed the normal function of the above proteins, which could account for the mechanism underlying Al3+-induced hepatotoxicity.
Studies have emphasised the importance of combustion-derived particles in eliciting adverse health effects, especially those produced by diesel vehicles. In contrast, few investigations have explored the potential toxicity of particles derived from tyre and brake wear, despite their significant contributions to total roadside particulate mass. The objective of this study was to compare the relative toxicity of compositionally distinct brake abrasion dust (BAD) and diesel exhaust particles (DEP) in a cellular model that is relevant to human airways. Although BAD contained considerably more metals/metalloids than DEP (as determined by inductively coupled plasma mass spectrometry) similar toxicological profiles were observed in U937 monocyte-derived macrophages following 24 h exposures to 4-25 μg ml-1 doses of either particle type. Responses to the particles were characterised by dose-dependent decreases in mitochondrial depolarisation (p ≤ 0.001), increased secretion of IL-8, IL-10 and TNF-α (p ≤ 0.05 to p ≤ 0.001) and decreased phagocytosis of S. aureus (p ≤ 0.001). This phagocytic deficit recovered, and the inflammatory response resolved when challenged cells were incubated for a further 24 h in particle-free media. These responses were abrogated by metal chelation using desferroxamine. At minimally cytotoxic doses both DEP and BAD perturbed bacterial clearance and promoted inflammatory responses in U937 cells with similar potency. These data emphasise the requirement to consider contributions of abrasion particles to traffic-related clinical health effects.
An early diagnostic biomarker for breast cancer is essential to improve outcome. High precision isotopic analysis, originating in Earth sciences, can detect very small shifts in metal pathways. For the first time, the natural intrinsic Zn isotopic compositions of various tissues in breast cancer patients and controls were determined. Breast cancer tumours were found to have a significantly lighter Zn isotopic composition than the blood, serum and healthy breast tissue in both groups. The Zn isotopic lightness in tumours suggests that sulphur rich metallothionein dominates the isotopic selectivity of a breast tissue cell, rather than Zn-specific proteins. This reveals a possible mechanism of Zn delivery to Zn-sequestering vesicles by metallothionein, and is supported by a similar signature observed in the copper isotopic compositions of one breast cancer patient. This change in intrinsic isotopic compositions due to cancer has the potential to provide a novel early biomarker for breast cancer.