Induction, regulation, degradation, and biological significance of mammalian metallothioneins

The metallothionein gene from the white shrimp Litopenaeus vannamei: characterization and expression in response to hypoxia

Aquatic animals encounter variation in oxygen tension that leads to the accumulation of reactive oxygen species (ROS) that can harm the organisms. Under these circumstances some organisms have evolved to tolerate hypoxia. In mammals, metallothioneins (MTs) protect against hypoxia-generated ROS. Here we report the MT gene from the shrimp Litopenaeus vannamei (LvMT). LvMT is differentially expressed in hemocytes, intestine, gills, pleopods, heart, hepatopancreas and muscle, with the highest levels in hepatopancreas and heart. LvMT mRNA increases during hypoxia in hepatopancreas and gills after 3 h at 1.5 mg L(-1) dissolved oxygen (DO). This gene structure resembles the homologs from invertebrates and vertebrates possessing three exons, two introns and response elements for metal response transcription factor 1 (MTF-1), hypoxia-inducible factor 1 (HIF-1) and p53 in the promoter region. During hypoxia, HIF-1/MTF-1 might participate inducing MT to contribute towards the tolerance to ROS toxicity. MT importance in aquatic organisms may include also ROS-detoxifying processes.

Impact of metallothionein gene polymorphisms on the risk of lung cancer in a Japanese population

Metallothioneins (MTs) are cysteine-rich proteins that act as antioxidants. A case-control study was conducted to assess the effects of gene polymorphisms in the MT region on the risk of lung cancer in Japanese subjects: 769 lung cancer cases and 939 non-cancer controls. Associations were evaluated using logistic regression models with adjustment for potential confounders (age, sex, and lifestyle factors including smoking, drinking, and green-yellow vegetable intake). We found five polymorphisms in the MT-1 gene region that showed statistically significant associations with lung cancer. Of these polymorphisms, rs7196890 showed the strongest association (odds ratio: 1.30, P = 0.004, 95% confidence interval: 1.09-1.55). The impact of the polymorphism decreased with the increase of smoking, and virtually no association with lung cancer was observed among heavy smokers whose pack-year values were 30 or more (odds ratio: 1.02, P = 0.93, 95% confidence interval: 0.67-1.55). These results suggest that polymorphisms in the MT gene are moderately associated with the risk of lung cancer and that the associations are modified by lifestyle factors.

Modeling Zn²⁺ release from metallothionein

Mammalian metallothioneins (MTs) comprise a Zn3Cys9 cluster in the β domain and a Zn4Cys11 cluster in the α domain. They play a crucial role in storing and donating Zn(2+) ions to target metalloproteins and have been implicated in several diseases, thus understanding how MTs release Zn(2+) is of widespread interest. In this work, we present a strategy to compute the free energy for releasing Zn(2+) from MTs using a combination of classical molecular dynamics (MD) simulations, quantum-mechanics/molecular-mechanics (QM/MM) minimizations, and continuum dielectric calculations. The methodology is shown to reproduce the experimental observations that (1) the Zn-binding sites do not have equal Zn(2+) affinity and (2) the isolated β domain is thermodynamically less stable and releases Zn(2+) faster with oxidizing agents than the isolated α domain. It was used to compute the free energies for Zn(2+) release from the metal cluster in the absence and presence of the protein matrix (protein architecture and coupled protein-water interactions) to yield the respective disulfide-bonded product. The results show the importance of the protein matrix as well as protein dynamics and coupled conformational changes in accounting for the differential Zn(2+)-releasing propensity of the two domains with oxidizing agents.

MT1M and MT1G promoter methylation as biomarkers for hepatocellular carcinoma

AIM: To investigate the potential of promoter methylation of two tumor suppressor genes (TSGs) as biomarkers for hepatocellular carcinoma (HCC).

METHODS: A total of 189 subjects were included in this retrospective cohort, which contained 121 HCC patients without any history of curative treatment, 37 patients with chronic hepatitis B (CHB), and 31 normal controls (NCs). DNA samples were extracted from 400 μL of serum of each subject and then modified using bisulfite treatment. Methylation of the promoters of the TSGs (metallothionein 1M, MT1M; and metallothionein 1G, MT1G) was determined using methylation-specific polymerase chain reaction. The diagnostic value of combined MT1M and MT1G promoter methylation was evaluated using the area under the receiver operating characteristic curves.

RESULTS: Our results indicated that the methylation status of serum MT1M (48.8%, 59/121) and MT1G (70.2%, 85/121) promoters in the HCC group was significantly higher than that in the CHB group (MT1M 5.4%, 2/37, P < 0.001; MT1G 16.2%, 6/37, P < 0.001) and NC group (MT1M 6.5%, 2/31, P < 0.001; MT1G 12.9%, 4/27, P < 0.001). Aberrant serum MT1M promoter methylation gave higher specificity to discriminate HCC from CHB (94.6%) and NCs (93.5%), whereas combined methylation of serum MT1M and MT1G promoters showed higher diagnostic sensitivity (90.9%), suggesting that they are potential markers for noninvasive detection of HCC. Furthermore, MT1M promoter methylation was positively correlated with tumor size (rs = 0.321, P < 0.001), and HCC patients with both MT1M and MT1G promoter methylation tended to show a higher incidence of vascular invasion or metastasis (P = 0.018).

CONCLUSION: MT1M and MT1G promoter methylation may be used as serum biomarkers for noninvasive detection of HCC.

Metallothionein-1 and nitric oxide expression are inversely correlated in a murine model of Chagas disease

Chagas disease, caused by Trypanosoma cruzi, represents an endemic among Latin America countries. The participation of free radicals, especially nitric oxide (NO), has been demonstrated in the pathophysiology of seropositive individuals with T. cruzi. In Chagas disease, increased NO contributes to the development of cardiomyopathy and megacolon. Metallothioneins (MTs) are efficient free radicals scavengers of NO in vitro and in vivo. Here, we developed a murine model of the chronic phase of Chagas disease using endemic T. cruzi RyCH1 in BALB/c mice, which were divided into four groups: infected non-treated (Inf), infected N-monomethyl-L-arginine treated (Inf L-NAME), non-infected L-NAME treated and non-infected vehicle-treated. We determined blood parasitaemia and NO levels, the extent of parasite nests in tissues and liver MT-I expression levels. It was observed that NO levels were increasing in Inf mice in a time-dependent manner. Inf L-NAME mice had fewer T. cruzi nests in cardiac and skeletal muscle with decreased blood NO levels at day 135 post infection. This affect was negatively correlated with an increase of MT-I expression (r = -0.8462, p < 0.0001). In conclusion, we determined that in Chagas disease, an unknown inhibitory mechanism reduces MT-I expression, allowing augmented NO levels.

Metallothionein - immunohistochemical cancer biomarker: a meta-analysis

Metallothionein (MT) has been extensively investigated as a molecular marker of various types of cancer. In spite of the fact that numerous reviews have been published in this field, no meta-analytical approach has been performed. Therefore, results of to-date immunohistochemistry-based studies were summarized using meta-analysis in this review. Web of science, PubMed, Embase and CENTRAL databases were searched (up to April 30, 2013) and the eligibility of individual studies and heterogeneity among the studies was assessed. Random and fixed effects model meta-analysis was employed depending on the heterogeneity, and publication bias was evaluated using funnel plots and Egger's tests. A total of 77 studies were included with 8,015 tissue samples (4,631 cases and 3,384 controls). A significantly positive association between MT staining and tumors (vs. healthy tissues) was observed in head and neck (odds ratio, OR 9.95; 95% CI 5.82-17.03) and ovarian tumors (OR 7.83; 1.09-56.29), and a negative association was ascertained in liver tumors (OR 0.10; 0.03-0.30). No significant associations were identified in breast, colorectal, prostate, thyroid, stomach, bladder, kidney, gallbladder, and uterine cancers and in melanoma. While no associations were identified between MT and tumor staging, a positive association was identified with the tumor grade (OR 1.58; 1.08-2.30). In particular, strong associations were observed in breast, ovarian, uterine and prostate cancers. Borderline significant association of metastatic status and MT staining were determined (OR 1.59; 1.03-2.46), particularly in esophageal cancer. Additionally, a significant association between the patient prognosis and MT staining was also demonstrated (hazard ratio 2.04; 1.47-2.81). However, a high degree of inconsistence was observed in several tumor types, including colorectal, kidney and prostate cancer. Despite the ambiguity in some tumor types, conclusive results are provided in the tumors of head and neck, ovary and liver and in relation to the tumor grade and patient survival.

Concentrations and distributions of metals in tissues of stranded green sea turtles (Chelonia mydas) from the southern Atlantic coast of Brazil

Silver (Ag), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) concentrations were analyzed in tissues of juvenile green sea turtles (Chelonia mydas) found stranded along the southern Atlantic coast in Brazil. Green sea turtles were collected (n=29), measured (curved carapace length: CCL) and had their muscle, liver, and kidney dissected for metal concentration measurements. Sex was identified in 18 individuals (10 females and 8 males) through gonad histology. No gender differences in CCL and tissue metal concentrations were observed. In the muscle, there was a negative correlation between CCL and Cd and Cu concentrations. Metal concentrations were lower in the muscle than in the liver and kidney. Zn concentration in the muscle was the highest of all metals analyzed (16.6 mg/kg). The kidney showed the highest concentrations of Pb, Cd and Zn (5.4, 28.3 and 54.3 mg/kg, respectively), while the liver had the highest values of Ag and Cu (0.8 and 100.9 mg/kg, respectively). Tissue Ag, Zn and Cd concentrations were similar to those found in green sea turtles from other regions while Cu and Pb values were elevated, likely due to the metal-rich water and sediment reported in the collection area. In the liver and kidney, concentrations of non-essential (Ag, Cd and Pb) and essential (Cu or Zn) metals were positively correlated, likely due to an induced metallothionein synthesis to protect tissue against the toxic effect of metals. This is the first study to report and correlate the concentrations of essential and non-essential metals in tissues of green sea turtles in the Brazilian southern Atlantic coast, an important feeding and developing area for this turtle species.

Hepatic metabolic response to restricted copper intake in a Niemann–Pick C murine model

Niemann–Pick C disease (NPC) is a vesicular trafficking disorder primarily caused by mutations in theNpc1gene and characterized by liver dysfunction and neuropathology.

Metallothionein 3: an androgen-upregulated gene enhances cell invasion and tumorigenesis of prostate carcinoma cells

BACKGROUND

Metallothioneins (MT1, MT2, MT3, and MT4) are regarded as modulators regulating a number of biological processes including cell proliferation, differentiation, and invasion. We determined the effects of androgen, cadmium, and arsenic on MT1/2 and MT3 in prostate carcinoma cells, and evaluated the functional effects of MT3 on cell proliferation, invasion, and tumorigenesis.

METHODS

We determined the expression of MT1/2 and MT3 in prostate carcinoma cells by immunoblotting assays or real-time reverse transcription-polymerase chain reactions. The effects of ectopic MT3 overexpression or MT3-knockdown on cell proliferation, invasion, and tumorigenesis were determined by (3) H-thymidine incorporation, matrigel invasion, and murine xenograft studies. The effects of androgen, cadmium, and arsenic on target genes were assessed using immunoblotting and reporter assays.

RESULTS

Androgen, cadmium, and arsenic treatments enhanced gene expression of MT1/2 and MT3 in prostate carcinoma LNCaP cells. Results of immunohistochemical staining indicated MT3 overexpression was found predominantly in the nuclear areas of PC-3 cells overexpressing MT3. Overexpression of MT3 significantly increased cell proliferation, invasion, and tumorigenic activities in PC-3 cells in vitro and in vivo. MT3 overexpression downregulated the gene expressions of N-myc downstream regulated gene 1 (Ndrg1) and maspin, and attenuated blocking effects of doxorubicin in PC-3 cells on cell proliferation. MT3-knockdown enhanced Ndrg1 and maspin expressions in LNCaP cells.

CONCLUSIONS

The experiments indicate that MT3 is an androgen-upregulated gene, and promotes tumorigenesis of prostate carcinoma cells. The downregulation of Ndrg1 and maspin gene expressions appears to account for the enhancement of proliferative and invasive functions of MT3 in PC-3 cells.

Characterization and metal-induced gene transcription of two new copper zinc superoxide dismutases in the solitary ascidian Ciona intestinalis

Antioxidant enzymes are known to protect living organisms against the oxidative stress risk, also induced by metals. In the present study, we describe the purification and molecular characterization of two Cu,Zn superoxide dismutases (SODs), referred to as Ci-SODa and Ci-SODb, from Ciona intestinalis, a basal chordate widely distributed in temperate shallow seawater. The putative amino acid sequences were compared with Cu,Zn SODs from other metazoans and phylogenetic analyses indicate that the two putative Ci-SODs are more related to invertebrate SODs than vertebrate ones. Both phylogenetic and preliminary homology modeling analyses suggest that Ci-SODa and Ci-SODb are extracellular and intracellular isoform, respectively. The mRNA of the two Cu,Zn SODs was localized in hemocytes and in ovarian follicular cells, as revealed by in situ hybridization. The time course of SOD mRNA levels in the presence of three different metals showed upregulation of ci-soda and inhibition of ci-sodb. Spectrophotometric analysis confirms the presence of SOD activity in Ciona tissues. Our in silico analyses of the ci-soda promoter region revealed putative consensus sequences similar to mammalian metal-responsive elements (MRE), suggesting that the transcription of these genes directly depends on metals. These data emphasize the importance of complex metal regulation of ci-soda and ci-sodb transcription, as components of an efficient detoxification pathway allowing the survival of C. intestinalis in continued, elevated presence of metals in the environment.

Expression of metallothionein-1 and metallothionein-2 as a prognostic marker in hepatocellular carcinoma

BACKGROUND AND AIMS

Metallothionein (MT)-1 and -2 are low-molecular weight, cysteine-rich, intracellular metal-binding proteins involved in diverse functions, such as metal homeostasis, cell cycle progression, cell differentiation, and carcinogenesis. This study investigated the expression of MT-1 and MT-2 as a prognostic marker in hepatocellular carcinoma (HCC).

METHODS

Expression of MT-1 and MT-2 were evaluated immunohistochemically in tissue microarrays containing samples from 370 HCCs, 336 adjacent noncancerous livers, and 12 normal livers. The relationships between MT-1 and MT-2 expression and the clinicopathological parameters of HCC were assessed.

RESULTS

The expression of MT-1 and MT-2 was uniformly strong in the nucleus and cytoplasm of normal liver, but varied in noncancerous livers and HCCs. Loss of nuclear and cytoplasmic expression was significantly more in HCCs than in adjacent noncancerous livers (P < 0.001). The loss of nuclear expression of MT-1 and MT-2 was significantly correlated with high Edmondson-Steiner grade and the presence of microvascular invasion (P < 0.05 each). Multivariate analysis showed that the loss of nuclear expression of MT-1 and MT-2 was an independent poor prognostic factor for both recurrence-free survival and overall survival.

CONCLUSIONS

The expression of MT-1 and MT-2 may play a role in HCC differentiation and carcinogenesis, and may predict prognosis in patients with HCC.

Methylmercury exposure increases lipocalin related (lpr) and decreases activated in blocked unfolded protein response (abu) genes and specific miRNAs in Caenorhabditis elegans

Methylmercury (MeHg) is a persistent environmental and dietary contaminant that causes serious adverse developmental and physiologic effects at multiple cellular levels. In order to understand more fully the consequences of MeHg exposure at the molecular level, we profiled gene and miRNA transcripts from the model organism Caenorhabditis elegans. Animals were exposed to MeHg (10 μM) from embryo to larval 4 (L4) stage and RNAs were isolated. RNA-seq analysis on the Illumina platform revealed 541 genes up- and 261 genes down-regulated at a cutoff of 2-fold change and false discovery rate-corrected significance q < 0.05. Among the up-regulated genes were those previously shown to increase under oxidative stress conditions including hsp-16.11 (2.5-fold), gst-35 (10.1-fold), and fmo-2 (58.5-fold). In addition, we observed up-regulation of 6 out of 7 lipocalin related (lpr) family genes and down regulation of 7 out of 15 activated in blocked unfolded protein response (abu) genes. Gene Ontology enrichment analysis highlighted the effect of genes related to development and organism growth. miRNA-seq analysis revealed 6-8 fold down regulation of mir-37-3p, mir-41-5p, mir-70-3p, and mir-75-3p. Our results demonstrate the effects of MeHg on specific transcripts encoding proteins in oxidative stress responses and in ER stress pathways. Pending confirmation of these transcript changes at protein levels, their association and dissociation characteristics with interaction partners, and integration of these signals, these findings indicate broad and dynamic mechanisms by which MeHg exerts its harmful effects.

Cytokine and gene transcription profiles of immune responses elicited by HIV lipopeptide vaccine in HIV-negative volunteers

OBJECTIVE

To dissect the biological mechanisms involved in the cellular responses to a candidate vaccine containing 5 HIV peptides coupled to a palmytoil tail (HIV-LIPO-5) in healthy volunteers, by using extensive immunogenicity assessments with different stimulation durations.

DESIGN

Immunogenicity substudy of a randomized phase II prophylactic HIV vaccine trial (ANRS VAC 18).

METHODS

HIV-LIPO-5 or placebo was administered at W0, W4, W12 and W24. Peripheral blood mononuclear cells from a subset of participants at W0 and W14 were stimulated with HIV-LIPO-5, Gag peptides contained in the vaccine and control peptides. ELISpot, lymphoproliferation, intracellular cytokine staining (ICS), cytokine multiplex and transcriptomic analyses were performed. Different time points and stimulation conditions were compared, controlling for test multiplicity.

RESULTS

Cultured ELISpot and lymphoproliferation responses were detected at W14. Ex-vivo ICS showed mainly interleukin (IL)-2-producing cells. Secretion of interferon (IFN)-γ, tumour necrosis factor (TNF)-α, IL-5 and IL-13 increased significantly after culture and Gag stimulation at W14 compared to W0. Metallothionein genes were consistently overexpressed after HIV-LIPO-5 stimulation at W0 and W14. At W14, significant probes increased substantially, including IFN-γ, CXCL9, IL2RA, TNFAIP6, CCL3L1 and IL-6. Canonical pathway analyses indicated a role of interferon signalling genes in response to HIV-LIPO-5.

CONCLUSION

HIV-LIPO-5 vaccination elicited Th1 and Th2 memory precursor responses and a consistent modulation in gene expression. The response profile before vaccination suggests an adjuvant effect of the lipid tail of HIV-LIPO-5. Our combined immunogenicity analyses allowed to identify a specific signature profile of HIV-LIPO-5 and indicate that HIV-LIPO-5 could be further developed as a prime in heterologous prime-boost strategies.

Metallic gold beads in hyaluronic acid: a novel form of gold-based immunosuppression? Investigations of the immunosuppressive effects of metallic gold on cultured J774 macrophages and on neuronal gene expression in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a neurodegenerative disease caused by recurring attacks of neuroinflammation leading to neuronal death. Immune-suppressing gold salts are used for treating connective tissue diseases; however, side effects occur from systemic spread of gold ions. This is limited by exploiting macrophage-induced liberation of gold ions (dissolucytosis) from gold surfaces. Injecting gold beads in hyaluronic acid (HA) as a vehicle into the cavities of the brain can delay clinical signs of disease progression in the MS model, experimental autoimmune encephalitis (EAE). This study investigates the anti-inflammatory properties of metallic gold/HA on the gene expression of tumor necrosis factor (Tnf-α), Interleukin (Il)-1β, Il-6, Il-10, Colony-stimulating factor (Csf)-v2, Metallothionein (Mt)-1/2, Bcl-2 associated X protein (Bax) and B cell lymphoma (Bcl)-2 in cultured J774 macrophages and in rodents with early stages of EAE. Cells grew for 5 days on gold/HA or HA, then receiving 1,000 ng/mL lipopolysaccharide (LPS) as inflammatory challenge. In the EAE experiment, 12 Lewis rats received gold injections and control groups included 11 untreated and 12 HA-treated EAE rats and five healthy animals. The experiment terminated day 9 when the first ten animals showed signs of EAE, only one of which were gold-treated (1p = 0.0367). Gene expression in the macrophages showed a statistically significant decrease in Il-6, Il-1β and Il-10-response to LPS; interestingly HA induced a statistically significant increase of Il-10. In the EAE model gene expression of inflammatory cytokines increased markedly. Compared to EAE controls levels of Tnf-α, Il-1β, Il-10, Il-6, IL-2, Ifn-γ, Il-17, transforming growth factor (Tgf)-β, superoxide dismutase (Sod)-2, Mt-2 and fibroblast growth factor (Fgf)-2 were lower in the gold-treated group. HA-treated animals expressed similar or intermediate levels. Omnibus testing for reduced inflammatory response following gold-treatment was not significant, but tendencies towards a decrease in the Sod-2, Fgf-2, Il-1β response and a higher Bdnf and IL-23 gene expression were seen. In conclusion, our findings support that bio-liberation of gold from metallic gold surfaces have anti-inflammatory properties similar to classic gold compounds, warranting further studies into the pharmacological potential of this novel gold-treatment and the possible synergistic effects of hyaluronic acid.

Use of brightness wavelet transformation for automated analysis of serum metallothioneins- and zinc-containing proteins by Western blots to subclassify childhood solid tumours

In this study, we determined serum levels of metallothioneins (MTs) and zinc in children with solid tumours (neuroblastoma, Hodgkin lymphoma, medulloblastoma, osteosarcoma, Ewing sarcoma and nephroblastoma) by differential pulse voltammetry Brdicka reaction and ELISA. Zn(II) level in patients sera was 40% compared to controls, contrariwise, MT level was 4.2 × higher in patients. No significant differences among single diagnoses were found both for Zn(II) and MT. When determined Zn(II)/MT ratio, in controls its value was 24.6, but it was 2.6 in patients. After Western-blotting with anti-MT and anti-Zn chicken antibodies, variable intensities of the bands within the samples were observed. The brightness curve obtained for each sample both for MT- and Zn blots was further analysed to produce a list of band positions together with some complementary information related to the intensity of the observed bands by the optimised algorithm. We constructed from those profiles decision trees that enable to distinguish different groups of tumours. The blood samples were heat-treated, in which we supposed mainly MT, but samples contained other thermostable Zn-containing proteins that were helpful for identification of embryonal tumours with 88% accuracy and for identification of sarcomas with 78% accuracy. In MT blots the accuracies were 53 and 45%, respectively. Simultaneous analysis of MT and Zn blots did not increased accuracy of identification neither in embryonal tumours (80%) nor in sarcomas. Those results are promising not only from diagnostic point of view but particularly in the area of studying of individual MT isoforms and their aggregates in malignant tumours.

Hypoxia and adipose tissue function and dysfunction in obesity

The rise in the incidence of obesity has led to a major interest in the biology of white adipose tissue. The tissue is a major endocrine and signaling organ, with adipocytes, the characteristic cell type, secreting a multiplicity of protein factors, the adipokines. Increases in the secretion of a number of adipokines occur in obesity, underpinning inflammation in white adipose tissue and the development of obesity-associated diseases. There is substantial evidence, particularly from animal studies, that hypoxia develops in adipose tissue as the tissue mass expands, and the reduction in Po(2) is considered to underlie the inflammatory response. Exposure of white adipocytes to hypoxic conditions in culture induces changes in the expression of >1,000 genes. The secretion of a number of inflammation-related adipokines is upregulated by hypoxia, and there is a switch from oxidative metabolism to anaerobic glycolysis. Glucose utilization is increased in hypoxic adipocytes with corresponding increases in lactate production. Importantly, hypoxia induces insulin resistance in fat cells and leads to the development of adipose tissue fibrosis. Many of the responses of adipocytes to hypoxia are initiated at Po(2) levels above the normal physiological range for adipose tissue. The other cell types within the tissue also respond to hypoxia, with the differentiation of preadipocytes to adipocytes being inhibited and preadipocytes being transformed into leptin-secreting cells. Overall, hypoxia has pervasive effects on the function of adipocytes and appears to be a key factor in adipose tissue dysfunction in obesity.

Permanence of molecular features of obesity in subcutaneous adipose tissue of ex-obese subjects

OBJECTIVE

Bariatric surgery represents a powerful tool for morbid obesity treatment. However, after stabilization of weight loss that follows surgical interventions, ex-obese patients face the problem of residual tissues removal. Actually, it is unknown whether the characteristics of this residual subcutaneous adipose tissue (SAT) are 'restored' with regard to molecular and morphological features.

DESIGN

To clarify this issue, we compared the SAT gene expression profile of ex-obese patients (ExOB-SAT, mean body mass index (BMI): 27.2±1.3 kg m(-2)) with that of lean (normal weight, NW-SAT, mean BMI: 22.6±1.1 kg m(-2)), overweight (OW-SAT, BMI: 27.65±0.2 kg m(-2)) and obese patients, according to BMI classes (OB1-SAT: 30 > or = BMI < or = 34.9, OB2-SAT: 35 > or = BMI < or = 39.9, OB3-SAT: BMI > or = 40).

SUBJECTS AND METHODS

A total of 58 samples of SAT were collected during surgical interventions. Gene expression levels were assessed by microarrays and significant genes were validated by RT-qPCR. Adipocyte hypertrophy, inflammatory infiltration and fibrosis were assessed by morphological techniques.

RESULTS

Global gene expression in ExOB-SAT was closely related to gene expression of OB3-SAT by hierarchical clustering procedures, in spite of different BMI. Metallothioneins (MT1A and MT2A) were the key over-expressed genes in both groups. At morphologic level, adipocyte hypertrophy and inflammatory infiltration improved after weight loss in ExOB-SAT, despite a persistence of fibrosis.

CONCLUSIONS

Taken together, these results demonstrate that SAT gene expression is not fully restored, even after an extensive and stable weight loss. The persistence of 'obesity molecular features' in ExOB-SAT suggests that the molecular signature of adipose tissue is not solely dependent on weight loss and may need longer time period to completely disappear.

Malondialdehyde and heavy metal concentrations in tissues of wild boar (Sus scrofa L.) from central Croatia

The aim of this research was to assess the degree of heavy metal (cadmium, lead and mercury) contamination of wild boars from central Croatia and thereby conduct further tests to connect the contamination to oxidative stress occurrence. The highest cadmium concentration was noticed in the kidneys of older boars, the lead concentration was approximately the same in the liver and kidneys, but it was much higher than the concentration in the muscles, while the highest mercury concentration was measured in the kidneys of all wild boars. The correlation between the malondialdehyde (MDA) and the heavy metal concentrations was higher in tissue samples taken from younger animals (1 to 3 years of age) than in the tissue samples taken from older animals (5 to 6 years of age). In the kidneys of all wild boars there was a statistically significant connection between the MDA and cadmium concentration; in the kidneys of younger wild boars there was a statistically significant connection between the MDA and lead concentration. Further research on this topic should focus on MDA potential to find its use, not only as a contamination biomarker in the area of ecotoxicology, but also in the evaluation of the hygienic acceptability of animal products.

Metallothioneins and zinc in cancer diagnosis and therapy

Metallothioneins (MTs) are involved in protection against oxidative stress (OS) and toxic metals and they participate in zinc metabolism and its homeostasis. Disturbing of zinc homeostasis can lead to formation of reactive oxygen species, which can result in OS causing alterations in immunity, aging, and civilization diseases, but also in cancer development. It is not surprising that altered zinc metabolism and expression of MTs are of great interest in the case of studying of oncogenesis and cancer prognosis. The role of MTs and zinc in cancer development is tightly connected, and the structure and function of MTs are strongly dependent on Zn²⁺ redox state and its binding to proteins. Antiapoptic effects of MTs and their interactions with proteins nuclear factor kappa B, protein kinase C, esophageal cancer-related gene, and p53 as well as the role of MTs in their proliferation, immunomodulation, enzyme activation, and interaction with nitric oxide are reviewed. Utilization of MTs in cancer diagnosis and therapy is summarized and their importance for chemoresistance is also mentioned.

Single nucleotide in the MTF-1 binding site can determine metal-specific transcription activation

Cells respond to changes in environment by shifting their gene expression profile to deal with the new conditions. The cellular response to changes in metal homeostasis is an important example of this. Transition metals such as iron, zinc, and copper are essential micronutrients but other metals such as cadmium are simply toxic. The cell must maintain metal concentrations in a window that supports efficient metabolic function but must also protect against the damaging effects of high concentrations of these metals. One way a cell regulates metal homeostasis is to control genes involved in metal mobilization and storage. Much of this regulation occurs at the level of transcription and the protein most responsible for this is the conserved metal responsive transcription factor 1 (MTF-1). Interestingly, the nature of the changes in the gene expression profile depends on the type of exposure. The cell somehow senses the kind of the metal challenge and responds appropriately. We have been using the Drosophila system to try to understand the mechanism of this metal discrimination. Using genome-wide mapping of MTF-1 binding under different metal stresses we find that, surprisingly, MTF-1 chooses different DNA binding sites depending on the specific nature of the metal insult. We also find that the type of binding site chosen is an important component of the capability to induce the metal-specific transcription activation.

Improved chronic fatigue symptoms after removal of mercury in patient with increased mercury concentration in hair toxic mineral assay: a case

Clinical manifestations of chronic exposure to organic mercury usually have a gradual onset. As the primary target is the nervous system, chronic mercury exposure can cause symptoms such as fatigue, weakness, headache, and poor recall and concentration. In severe cases chronic exposure leads to intellectual deterioration and neurologic abnormality. Recent outbreaks of bovine spongiform encephalopathy and pathogenic avian influenza have increased fish consumption in Korea. Methyl-mercury, a type of organic mercury, is present in higher than normal ranges in the general Korean population. When we examine a patient with chronic fatigue, we assess his/her methyl-mercury concentrations in the body if environmental exposure such as excessive fish consumption is suspected. In the current case, we learned the patient had consumed many slices of raw tuna and was initially diagnosed with chronic fatigue syndrome. Therefore, we suspected that he was exposured to methyl-mercury and that the mercury concentration in his hair would be below the poisoning level identified by World Health Organization but above the normal range according to hair toxic mineral assay. Our patient's toxic chronic fatigue symptoms improved after he was given mercury removal therapy, indicating that he was correctly diagnosed with chronic exposure to organic mercury.

Down-regulation of metallothionein 1 and 2 after exposure to electromagnetic field in mouse testis

BACKGROUND

It is proved that testis is sensitive to electromagnetic field (EMF) and its damage results in infertility. Exposure to EMF induces reactive oxygen species production and affects on anti-oxidants defense mechanisms. Metallothionein (MT) is a name for a group of low molecular weight (6-7 kDa), sulfhydryl rich proteins. Expression of MT1 and MT2 genes in testis tissue after EMF exposure was aimed in this study.

METHODS

Male BALB/c mice (8 weeks old) were exposed to 3 MT EMF for 8 weeks, 4 hours/day. After 8 weeks, the mice were sacrificed and the testis tissue was removed. The testis pieces were stained with hematoxylin and eosin and analyzed under an optical microscope. Assessment of MT1 and MT2 genes and also protein expression was performed by real-time PCR and Western-blot, respectively.

RESULTS

In light microscopic observation, the number of primary spermatocytes was increased significantly in EMF group (P < 0.01). In addition, in interstitial space, the number of leydig cells was increased significantly in EMF group (P < 0.01) and basement membrane thickness was increased as well. MT1 and MT2 genes were down-regulated significantly in testis tissue of mice exposed to EMF both in mRNA and protein level compared to control.

CONCLUSION

It is clear that MT is mediated in testis development and spermatogenesis. Down-regulation of MT1 and MT2 after EMF in mouse testis might be followed by some consequences that result in infertility.

Mammalian metallothioneins: properties and functions

Metallothioneins (MT) are a family of ubiquitous proteins, whose role is still discussed in numerous papers, but their affinity to some metal ions is undisputable. These cysteine-rich proteins are connected with antioxidant activity and protective effects on biomolecules against free radicals, especially reactive oxygen species. In this review, the connection between zinc(II) ions, reactive oxygen species, heavy metal ions and metallothioneins is demonstrated with respect to effect of these proteins on cell proliferation and a possible negative role in resistance to heavy metal-based and non-heavy metal-based drugs.

Comparative study on metal homeostasis and detoxification in two Antarctic teleosts

The main characteristic of Antarctic seawater is its low constant temperature and its high concentration of O(2), which can increase the formation rate of reactive oxygen species (ROS), together with a natural occurrence of elevated cadmium and copper levels. In the present paper, we studied the presence of cadmium, copper and zinc, metallothioneins (MTs) and glutathione (GSH), and antioxidant enzyme activities in the Antarctic teleosts Trematomus bernacchii and Trematomus newnesi, in order to determine the influence of the peculiar physico-chemical features of the Antarctic marine environment on these physiological defence systems in two species of teleosts. In both of them, cadmium and copper accumulation occurs mostly in the liver. T. bernacchii accumulates zinc mostly in the hepatic tissue, whereas T. newnesi does not show a preferential accumulation site. In addition to the intra-specific analysis, we decided to compare the two species of the Trematomus genus in order to verify if the different feeding habits and motility of these fish affects metal accumulation. Our results show that the liver of T. bernacchii accumulates cadmium and zinc at a higher extent with respect to T. newnesi. Glutathione (GSH) and metallothioneins (MTs) are present in great quantity in the liver of both species. Moreover liver is the tissue which generally showed the highest antioxidant enzyme levels. The results provide further insights in the physiological mechanisms evolved by animals living in this extreme environment.

Functional characterization of four metallothionein genes in Daphnia pulex exposed to environmental stressors

We characterized the metallothionein genes (Mt1, Mt2, Mt3, and Mt4) in Daphnia pulex on both molecular and ecotoxicological level. We therefore conducted a bioinformatical analysis of the gene location and predicted protein sequence, and screened the upstream flanking region for regulatory elements. The number of these elements and their positions relative to the start codon varied strongly among the four genes and even among two gene duplicates (Mt1A and Mt1B), suggesting different roles of the four proteins in the organisms' response to stress. We subsequently conducted a chronic 16-day exposure of D. pulex to different environmental stressors (at sublethal levels causing approximately 50% reduction in reproduction). Based on prior knowledge, we exposed them to the metals Cd, Cu, and Ni, the moulting hormone hydroxyecdysone (20E), and the oxidative stressors cyanobacteria (Microcystis aeruginosa), and paraquat (Pq). We then compared mRNA expression levels of the four Mt genes under these stress conditions with control conditions in "The Chosen One" clone (TCO), for which the full genome was sequenced and annotated. All together, the mRNA expression results under the different stress regimes indicate that different Mt genes may play different and various roles in the response of D. pulex to stress and that some (but not all) of the differences among the four genes could be related to the pattern of regulatory elements in their upstream flanking region.

Expression of metallothioneins in cutaneous squamous cell carcinoma and actinic keratosis

Metallothioneins (MT) are low-molecular weight proteins implicated in heavy metal detoxification, zinc and cooper homeostasis and cell protection against free radicals. In variety of cancers MT-overexpression was shown, but there are just a few studies on the role of MT in skin carcinogenesis. Current study was undertaken to evaluate MT and Ki-67 expression in pre-cancerous skin lesions as well as in fully developed skin cancers. 73 squamous cell carcinomas (SCC), 23 actinic keratoses (AK) and 20 normal skin samples were included in the study. In obtained paraffin sections immunohistochemical reactions were performed. MT-expression in SCC (mean 2.89 ± 1.83) was significantly higher than in AK (mean 1.69 ± 1.26)(p = 0.006) and higher than in normal skin (mean 2 ± 0.79) (p = 0.0075). The MT-expression positively correlated with Ki-67 expression (R = 0.28; p = 0.017) in SCC and in AK (R = 0.49; p = 0.018). Various clinico-pathological variables, e.g. morphology, size of lesions and the depth of neoplastic infiltration were not associated to MT-expression in both SCC and AK. The grade of histological differentiation of SCC correlated positively with Ki-67 antigen (p < 0.001) and did not correlate with MT-expression (p = 0.06). Ki-67 expression was higher in SCC and in AK than in healthy skin (p = 0,003). In SCC and in AK expression of Ki-67 antigen correlated positively with MT-expression (respectively p = 0.017 and p = 0.018). MT may serve as a good markers of proliferation in SCC and AK. MT-overexpression in SCC may suggest a potential role of MT in skin carcinogenesis.

Downregulation of metallothionein 1F, a putative oncosuppressor, by loss of heterozygosity in colon cancer tissue

PURPOSE

Downregulation of metallothionein (MT) genes has been reported in several tumors with discrepant results. This study is to investigate molecular mechanism of MT gene regulation in colon cancer which is characterized by tumor suppressor gene alterations.

EXPERIMENTAL DESIGN

Integral analysis of microarray data with loss of heterozygosity (LOH) information was employed. Quantitative real-time PCR and immunohistochemistry were used to validate MT isoform expression in colon cancer tissues and cell lines. The effects of MT1F expression on RKO cell survival and tumorigenesis was analyzed. Bisulphite sequencing PCR (BSP) and methylation-specific PCR were employed to detect the methylation status of the MT1F gene in colon cancer tissues and cell lines. DNA sequencing was used to examine the LOH at the MT1F locus.

RESULTS

MT1F, MT1G, MT1X, and MT2A gene expression was significantly downregulated in colon cancer tissue (p<0.05). Exogenous MT1F expression increased RKO cell apoptosis and inhibited RKO cell migration, invasion and adhesion as well as in vivo tumorigenicity. Downregulation of MT1F gene in majority of human colon tumor tissues is mainly through mechanism by loss of heterozygosity (p=0.001) while CpG island methylation of MT1F gene promoter region was only observed in poorly differentiated, MSI-positive RKO and LoVo colon cancer cell lines.

CONCLUSIONS

MT1F is a putative tumor suppressor gene in colon carcinogenesis that is downregulated mainly by LOH in colon cancer tissue. Further studies are required to elucidate a possible role for MT1F downregulation in colon cancer initiation and/or progression.

Metallothionein expression in mobile tongue squamous cell carcinoma: associations with clinicopathological parameters and patient survival

AIMS

Metallothionein (MT) has been implicated in several aspects of cancer pathobiology, such as differentiation, proliferation, apoptosis and invasion. The aim of the present study was to evaluate the clinical significance of MT expression in mobile tongue squamous cell carcinoma (SCC).

METHODS AND RESULTS

MT protein expression was assessed immunohistochemically on 49 mobile tongue SCC specimens, and was analysed in relation to clinicopathological characteristics, and overall and disease-free patient survival. All of the examined mobile tongue SCC cases showed MT positivity in tumour cells; however, neither MT overexpression nor staining intensity was significantly associated with clinicopathological parameters. MT cellular distribution was significantly associated with histopathological grade of differentiation and depth of invasion (P = 0.0188 and P = 0.0484, respectively). MT staining intensity was identified as a significant predictor of overall patient survival at both univariate (P = 0.0377) and multivariate (P = 0.0472) levels. Twenty-seven (55.10%) of the examined SCC cases showed MT positivity in squamous tongue epithelium adjacent to the tumour, the MT positivity being correlated with depth of invasion (P = 0.0281), vascular invasion (P = 0.0194), and the existence of lymph node metastases (P = 0.0194).

CONCLUSIONS

MT may be implicated in the development and progression of mobile tongue SCC and could be considered as a useful clinical marker for patient management and prognosis.

Apolipoprotein E genotype affects tissue metallothionein levels: studies in targeted gene replacement mice

The apolipoprotein E (APOE) genotype is an important risk factor for ageing and age-related diseases. The APOE4 genotype (in contrast to APOE3) has been shown to be associated with oxidative stress and chronic inflammation. Metallothioneins (MT) exhibit antioxidant and anti-inflammatory activity, and MT overexpression has been shown to increase lifespan in mice. Interactions between APOE and MT, however, are largely unknown. Hence, we determined the effect of the APOE4 versus APOE3 genotype on MT levels in targeted gene replacement mice. APOE4 versus APOE3 mice exhibited significantly lower hepatic MT1 and MT2 mRNA as well as lower MT protein levels. The decrease in hepatic MT protein levels in APOE4 as compared to APOE3 mice was accompanied by lower nuclear Nrf1, a protein partly controlling MT gene expression. Cell culture experiments using hepatocytes identified allyl-isothiocyanate (AITC) as a potent MT inductor in vitro. Therefore, we supplemented APOE3 and APOE4 mice with AITC. However, AITC (15 mg/kg b.w.) could only partly correct for decreased MT1 and MT2 gene expression in APOE4 mice in vivo. Furthermore, cholesterol significantly decreased both Nrf1 and MT mRNA levels in Huh7 cells indicating that differences in MT gene expression between the two genotypes could be related to differences in hepatic cholesterol concentrations. Overall, present data suggest that the APOE genotype is an important determinant of tissue MT levels in mice and that MT gene expression may be impaired by the APOE4 genotype.

Copper export from cultured astrocytes

Copper is an essential trace metal that is required as a catalytic co-factor or a structural component of several important enzymes. However, since excess of copper can also harm cells due to its potential to catalyse the generation of toxic reactive oxygen species, transport of copper and the cellular copper content are tightly regulated. Astrocytes are known to efficiently take up copper ions, but it was not known whether these cells are also able to export copper. Treatment of astrocyte-rich primary cultures for 24 h with copper chloride caused a concentration-dependent increase in the specific cellular copper content. During further 24 h incubation in the absence of copper chloride, the copper-loaded astrocytes remained viable and released up to 45% of the accumulated copper. The rate of copper export was proportional to the amount of cellular copper, was almost completely prevented by lowering the incubation temperature to 4 °C and was partly prevented by the endocytosis inhibitor amiloride. Copper export is most likely mediated by the copper ATPase ATP7A, since this transporter is expressed in astrocyte cultures and its cellular location is strongly affected by the absence or the presence of extracellular copper. The potential of cultured astrocytes to export copper suggests that astrocytes provide neighbouring cells in brain with this essential trace element.

Lanthanum(III) impacts on metallothionein MTT1 and MTT2 from Tetrahymena thermophila

Metallothionein MTT1 and MTT2 from Tetrahymena thermophila are sulfydryl-rich proteins that can bind to and are inducible by heavy metals such as mercury, cadmium, zinc, and copper. However, little is known about the induction and binding of T. thermophila metallothionein by trivalent metals. In this study, we found that 10-80 μM La(3+) can promote Tetrahymena cells proliferation, and fluorescence spectrum analysis showed that La(3+) can enter T. thermophila cells. Real-time quantitative polymerase chain reaction showed La(3+) induced the expression of MTT1 and MTT2. Furthermore, Fluorescence analysis indicated La(3+) bind to MTT1 and MTT2. These results implied that La(3+) could interact with MTT1 and MTT2 via aspartic or glutamic acid oxygen atoms.

Effects of the interleukin-6 (IL-6) polymorphism on toxic metal and trace element levels in placental tissues

The placenta is a crucial organ of fetal origin that functions in providing nutrients to the fetus from the mother. During pregnancy, the need for essential micronutrients, such as Fe and Zn, increases due to the requirements of the growing fetus. Maternal Fe deficiency induces an increase in Cu levels and can also affect cytokine levels in the placenta. On the other hand, Cu deficiency, although not as common, can also have destructive effects on the fetus. Interleukin-6 (IL-6) is a pleiotropic cytokine with a wide range of biological activities, including such as immune responses, acute-phase reactions, and inflammation. The placenta produces a significant amount of IL-6 during pregnancy. The effects of the IL-6 -174 G/C single nucleotide polymorphism (SNP) on IL-6 gene transcription and on plasma cytokine levels were assessed in the present study. We investigated the association between the IL-6 -174 G/C polymorphism and trace element/toxic metal levels in placental tissues. For the purposes of this study, 95 healthy volunteers were evaluated. Presence of the IL-6 polymorphism was determined using the standard polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique, and metal levels were analyzed by atomic absorption spectrometry (AAS). Based on our data, there were no significant associations between the IL-6 -174 G/C polymorphism and Pb, Cd, Fe, or Zn levels in the placental tissues (p>0.05), but a statistically significant association was detected between the polymorphism and Cu levels (p=0.016). We determined that the mean Cu levels in the placental tissues from individuals with GG, GC and CC genotypes were 5.62±1.98, 6.22±3.22 and 8.00±1.32 ppm, respectively, whereas the overall mean Cu level from the placental tissues was 5.98±2.51 ppm.

The Casuarina glauca metallothionein I promoter in nodulated transgenic hairy roots of the actinorhizal plant Datisca glomerata

The activity of the promoter of a metallothionein gene expressed in actinorhizal nodules of Casuarina glauca Sieber ex Spreng., CgMT1, has previously been analysed in Casaurinaceae and in tobacco (Nicotiana tabacum L.), Arabidopsis and rice. In all these plants, the promoter showed high activity in the root cortex and epidermis, making it a useful tool for the expression of transgenes. Therefore, its activity was now analysed in transgenic root systems of Datisca glomerata (C. Presl) Baill, an actinorhizal plant from a different phylogenetic group than C. glauca, using the same CgMT1::GUS fusion as in previous studies. However, in contrast with all other plant species examined previously, the CgMT1::GUS construct showed no activity at all in D. glomerata hairy roots: the expression pattern in nodules resembled that found in C. glauca nodules. This is probably due to the changed hormone balance in hairy roots since experiments on the CgMT1::GUS construct in transgenic Arabidopsis showed that CgMT1 promoter activity was repressed by auxin or cytokinin, respectively. Yet, in hairy roots of the model legume Lotus japonicus L. induced by the same Agrobacterium rhizogenes strain, the CgMT1 promoter was active in roots and not in nodules. These results indicate that although the expression of pRi T-DNA genes leads to changes in root hormone balance, these changes do not abolish the differences in phytohormone levels or sensitivity between plant species. Therefore, gene expression data obtained using transgenic hairy root systems have to be viewed with care, not only due to the disturbed hormone balance, but also because the effects of the pRI-T-DNA genes can differ between species.

Metallothionein promotes regenerative axonal sprouting of dorsal root ganglion neurons after physical axotomy

Prior studies have reported that metallothionein I/II (MT) promote regenerative axonal sprouting and neurite elongation of a variety of central nervous system neurons after injury. In this study, we evaluated whether MT is capable of modulating regenerative axon outgrowth of neurons from the peripheral nervous system. The effect of MT was firstly investigated in dorsal root ganglion (DRG) explants, where axons were scratch-injured in the presence or absence of exogenous MT. The application of MT led to a significant increase in regenerative sprouting of neurons 16 h after injury. We show that the pro-regenerative effect of MT involves an interaction with the low-density lipoprotein receptor megalin, which could be blocked using the competitive antagonist RAP. Pre-treatment with the mitogen-activated protein kinase (MAPK) inhibitor PD98059 also completely abrogated the effect of exogenous MT in promoting axonal outgrowth. Interestingly, we only observed megalin expression in neuronal soma and not axons in the DRG explants. To investigate this matter, an in vitro injury model was established using Campenot chambers, which allowed the application of MT selectively into either the axonal or cell body compartments after scratch injury was performed to axons. At 16 h after injury, regenerating axons were significantly longer only when exogenous MT was applied solely to the soma compartment, in accordance with the localized expression of megalin in neuronal cell bodies. This study provides a clear indication that MT promotes axonal regeneration of DRG neurons, via a megalin- and MAPK-dependent mechanism.

Protective effect of pretreatment with cilostazol on cytotoxicity of cadmium and arsenite in cultured vascular endothelial cells

Cilostazol, an antiplatelet drug, exhibits antiatherogenic effects. The purpose of the present study was to determine the effect of cilostazol on the cytotoxicity of cadmium (Cd) and arsenite (iAs(III)), which involved in the pathogenesis of vascular disorders such as atherosclerosis, in cultured vascular endothelial cells. Cytotoxicity was evaluated by the lactate dehydrogenase leakage assay and morphological observation. Cd (10 µM) -induced cytotoxicity was prevented by pretreatment with cilostazol (30 and 100 µM) and simultaneous treatment with cilostazol (100 µM). On the other hand, iAs(III)-induced cytotoxicity was blocked by pretreatment with cilostazol (30 and 100 µM) but not simultaneous treatment with cilostazol. The mRNA level and the protein level of metallothionein (MT) were significantly increased by cilostazol in the cells. These results suggested, therefore, that pretreatment with cilostazol effectively prevents the cytotoxicity of Cd and iAs(III) in cultured vascular endothelial cells, at least in part through the induction of MT synthesis.

The potential effect of metallothionein 2A -5A/G single nucleotide polymorphism on blood cadmium, lead, zinc and copper levels

Metallothioneins (MTs) are low molecular weight, cysteine-rich, metal-binding proteins. Because of their rich thiol groups, MTs bind to the biologically essential metals and perform these metals' homeostatic regulations; absorb the heavy metals and assist with their transportation and extraction. The aim of this study was to investigate the association between the metallothionein 2A (MT2A) core promoter region -5 A/G single nucleotide polymorphism (SNP) and Cd, Pb, Zn and Cu levels in the blood samples. MT2A polymorphism was determined by the standard polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique using the 616 blood samples and the genotype frequencies were found as 86.6% homozygote typical (AA), 12.8% heterozygote (AG) and 0.6% homozygote atypical (GG). Metal levels were analyzed by dual atomic absorption spectrophotometer system and the average levels of Cd, Pb, Zn and Cu in the blood samples were 1.69±1.57 ppb, 30.62±14.13 ppb, 0.98±0.49 ppm and 1.04±0.45 ppm, respectively. As a result; highly statistically significant associations were detected between the -5 A/G core promoter region SNP in the MT2A gene and Cd, Pb and Zn levels (p=0.004, p=0.012 and p=0.002, respectively), but no association was found with Cu level (p=0.595). Individuals with the GG genotype had statistically lower Zn level and higher Cd and Pb levels in the blood samples than individuals with AA and AG genotypes. This study suggests that having the GG genotype individuals may be more sensitive for the metal toxicity and they should be more careful about protecting their health against the toxic effects of the heavy metals.

The toxicity redox mechanisms of cadmium alone or together with copper and zinc homeostasis alteration: its redox biomarkers

Cadmium (Cd) is a toxic metal and can induce and/or promote diseases in humans (cancer, aging diseases, kidney and bone diseases, etc.). Its toxicity involves many mechanisms including the alteration of copper (Cu) and zinc (Zn) homeostasis leading to reactive oxygen species (ROS) production, either directly or through the inhibition of antioxidant activities. Importantly, ROS can induce oxidative damages in cells. Cadmium, Cu and Zn are also able to induce glutathione (GSH) and metallothioneins (MT) synthesis in a cell-type-dependent manner. As a consequence, the effects induced by these three metals result simultaneously from the inhibition of antioxidant activities and the induction of other factors such as GSH and MT synthesis. MT levels are regulated not only by the p53 protein in a cell-type-dependent manner, or by transcription factors such as metal-responsive transcription factor 1 (MTF-1) and cellular Zn levels but also by cellular GSH level. As described in the literature, DNA damage, GSH and MT levels are sensitive biomarkers used to identify Cd-induced toxicity alone or together with Cu and Zn homeostasis alteration.

Comparative nephrotoxicity of Cisplatin and nedaplatin: mechanisms and histopathological characteristics

The antineoplastic platinum complexes cisplatin and its analogues are widely used in the chemotherapy of a variety of human malignancies, and are especially active against several types of cancers. Nedaplatin is a second-generation platinum complex with reduced nephrotoxicity. However, their use commonly causes nephrotoxicity due to a lack of tumor tissue selectivity. Several recent studies have provided significant insights into the molecular and histopathological events associated with nedaplatin nephrotoxicity. In this review, we summarize findings concerning the renal histopathology and molecular pathogenesis induced by antineoplastic platinum complexes, with a particular focus on the comparative nephrotoxicity of cisplatin and nedaplatin in rats.