A review of molecular events of cadmium-induced carcinogenesis

Nickel and cadmium-induced SLBP depletion: A potential pathway to metal mediated cellular transformation

Both nickel and cadmium compounds have been established as group I carcinogens for several decades. Despite over-whelming evidence of these compounds' carcinogenicity in humans, the specific underlying molecular mechanisms that govern metal induced cellular transformation remain unclear. In this study, we found that there were slightly different effects on decreased SLBP mRNA and protein as well as increased polyA H3.1 in our nickel exposed cells. This suggested that nickel and arsenic have similar effects on canonical histone mRNA transcription and translation. We also saw that the depletion of SLBP protein was reversed by inhibiting the proteosome. Finally, we showed that inhibiting the SLBP mRNA and protein levels were rescued by epigenetic modifiers suggesting that nickel's effects on SLBP may be mediated via epigenetic mechanisms. Taken together these results suggest a similar mechanism by which both arsenic and nickel may exert their carcinogenic effects.

Role of connexin 43 in cadmium-induced proliferation of human prostate epithelial cells

Connexins (Cxs), the subunits of gap junction channels, are involved in many physiological processes. Aberrant control of Cxs and gap junction intercellular communication may contribute to many diseases, including the promotion of cancer. Cd exposure is associated with increased risk of human prostate cancer and benign prostatic hyperplasia. The roles of Cxs in the effects of Cd on the prostate have, however, not been reported previously. In this study, the human prostate epithelial cell line RWPE-1 was exposed to Cd. A low dose of Cd stimulated cell proliferation along with a lower degree of gap junction intercellular communication and an elevated level of the protein Cx43. Cd exposure increased the levels of intracellular Ca²⁺ and phosphorylated Cx43 at the Ser368 site. Knockdown of Cx43 using siRNA blocked Cd-induced proliferation and interfered with the Cd-induced changes in the protein levels of cyclin D1, cyclin B1, p27^Kip1 (p27) and p21^Waf1/Cip1 (p21). The increase in Cx43 expression induced by Cd was presumably mediated by the androgen receptor, because it was abolished upon treatment with the androgen receptor antagonist, flutamide. Thus, a low dose of Cd promotes cell proliferation in RWPE-1, possibly mediated by Cx43 expression through an effect on cell cycle-associated proteins. Cx43 might be a target for prostatic diseases associated with Cd exposure. Copyright © 2017 John Wiley & Sons, Ltd.

Cell specific stress responses of cadmium-induced cytotoxicity

Cadmium is one of the age old toxic heavy metal, detrimental to the biological system. In this study, we explored the cellular and molecular mechanisms induced on exposure to different concentrations of cadmium chloride (CdCl₂), on three different human cell lines with wild type p53, viz., A549, HEK293 and HCT116. We investigated whether the cellular responses followed, displayed any specific pattern related to their viability, mitochondrial respiration, DNA damage and apoptotic gene expression. All the cell lines showed decrease in viability following exposure to CdCl₂. p53 was transcriptionally down regulated in all the three cell lines, but with different extents, in response to increasing concentration of cadmium. The cellular responses of the three cell lines were compared with that of a p53 knock out cell line (HCT116p53-/-). The p53 knock out cell line was highly sensitive to cadmium-induced toxicity; so was the cell line in which p53 mRNA expression was highly down regulated. This might implicate an unknown protective role of p53 signaling during heavy metal toxicity and that one of the possible mechanisms by which cadmium manifests its cytotoxic effect is through the transcriptional down regulation of p53 gene.

A survey of the mechanisms of action of anticancer transition metal complexes

Metal complexes have been the subject of numerous investigations in oncology but, despite the plethora of newly synthesized compounds, their precise mechanisms of action remain generally unknown or, for the best, incompletely determined. The continuous development of efficient and sensitive techniques in analytical chemistry and molecular biology gives scientists new tools to gather information on how metal complexes can be effective toward cancer. This review focuses on recent findings about the anticancer mechanism of action of metal complexes and how the ligands can be used to tune their pharmacological and physicochemical properties.

Determinants of serum cadmium levels in a Northern Italy community: A cross-sectional study

INTRODUCTION

Cadmium (Cd) is a heavy metal and a serious environmental hazard to humans. Some uncertainties still exist about major sources of Cd exposure in non-occupationally exposed subjects in addition to cigarette smoking, such as diet and outdoor air pollution. We sought to determine the influence of these sources on a biomarker of exposure, serum Cd concentration.

METHODS

We recruited 51 randomly selected residents from an Italian urban community, from whom we obtained detailed information about dietary habits and smoking habits, and a blood sample for serum Cd determination. We also assessed outdoor air Cd exposure, by modeling outdoor air levels of particulate matter ≤10µm (PM10) from motorized traffic at geocoded subjects' residence.

RESULTS

In crude analysis, regression beta coefficients for dietary Cd, smoking and PM10 on serum Cd levels were 0.03 (95% CI -0.83 to 0.88), 6.96 (95% CI -0.02 to 13.95) and 0.62 (95% CI -0.19 to 1.43), respectively. In the adjusted analysis, regression beta coefficients were -0.34 (95% CI -1-40 to 0.71), 5.81 (95% CI -1.43 to 13.04) and 0.47 (95% CI -0.35 to 1.29), respectively.

CONCLUSION

Cigarette smoking was the most important factor influencing serum Cd in our non-occupationally exposed population, as expected, while dietary Cd was not associated with this biomarker. Outdoor air pollution, as assessed through exposure to particulate matter generated by motorized traffic, was an additional source of Cd exposure.

Cadmium-induced oxidative damages in the human BJAB cells correlate with changes in intracellular trace elements levels and zinc transporters expression

Cadmium (Cd), a potent toxic heavy metal, is a widespread environmental contaminant. Its cellular traffic via pathways dedicated to transition metals contributes to the toxicity mechanisms. Zinc (Zn) homeostasis is complex, involving both zinc importers (Zip) and zinc exporters (ZnT). Cellular signal transduction pathways are influenced by Zn and redox status of the cell. The aim of the present study is to examine if the accumulation of Cd in the human lymphocyte B cell line BJAB and its capacity to promote oxidative stress and adverse effects could result from changes in the mRNA expression pattern of Zn transporters and metallothioneins. Cells were exposed to 5, 10, 20 and 40μM of CdCl₂ equivalent to 0.91, 1.83, 3.66 and 7.33μg/ml respectively, for 24h. Cd significantly reduced the viability of BJAB cells and induced a dose-dependent increase in DNA damage. Cd also induced the formation of 8-hydroxy-2'-deoxyguanosine adducts and augmented MTF1 expression in BJAB cells. We observed interesting responses in relative gene expression to Cd exposure among the seven transporters we analyzed. Cd exposure increased the expression of DMT1 and caused an up-regulation of ZnT1. However, the T calcium channel alpha1G subunit could not be detected. A change in expression of ZnTs and Zips in response to Cd exposure emphasizes the involvement of Zn transporters in Cd cellular metabolism and induced oxidative stress.

Expression of specific genes involved in Cd uptake, translocation, vacuolar compartmentalisation and recycling in Populus alba Villafranca clone

Cadmium (Cd) is a heavy metal toxic to humans and its occurrence in soils represents a significant environmental problem. Poplar trees may provide one possible option to help remove Cd contamination from soil. However, before this is practicable, the ability of poplar to accumulate Cd needs to be enhanced. A better understanding of the genes involved in Cd accumulation in poplar would help to achieve this goal. Here, we monitored the expression of genes known to be involved in Cd uptake, accumulation and translocation from other species, in order to provide information on their potential role in Cd accumulation in poplar. Cd concentration in poplar was significantly higher in roots than in stem and leaves in Cd treated plants. Expression of the poplar homologues of IRT1, NRAMP and OPT3 was initially increased after exposure to Cd but reduced after longer term Cd exposure. Exposure to Cd also influenced the accumulation of Fe, Ca, Cu, Mg and Mn in poplar. In particular, Cd treated plants had a higher concentration of Fe, Ca, Cu, and Mg in leaves and stem compared to control plants after one day and one week of experiment; while in roots after one month Cd treated plants had a lower concentration of Mn, Fe, Cu, Co, and Mg.

Epigenetics and inheritance of phenotype variation in livestock

Epigenetic inheritance plays a crucial role in many biological processes, such as gene expression in early embryo development, imprinting and the silencing of transposons. It has recently been established that epigenetic effects can be inherited from one generation to the next. Here, we review examples of epigenetic mechanisms governing animal phenotype and behaviour, and we discuss the importance of these findings in respect to animal studies, and livestock in general. Epigenetic parameters orchestrating transgenerational effects, as well as heritable disorders, and the often-overlooked areas of livestock immunity and stress, are also discussed. We highlight the importance of nutrition and how it is linked to epigenetic alteration. Finally, we describe how our understanding of epigenetics is underpinning the latest cancer research and how this can be translated into directed efforts to improve animal health and welfare.

Epigenetics and inheritance of phenotype variation in livestock

Epigenetic inheritance plays a crucial role in many biological processes, such as gene expression in early embryo development, imprinting and the silencing of transposons. It has recently been established that epigenetic effects can be inherited from one generation to the next. Here, we review examples of epigenetic mechanisms governing animal phenotype and behaviour, and we discuss the importance of these findings in respect to animal studies, and livestock in general. Epigenetic parameters orchestrating transgenerational effects, as well as heritable disorders, and the often-overlooked areas of livestock immunity and stress, are also discussed. We highlight the importance of nutrition and how it is linked to epigenetic alteration. Finally, we describe how our understanding of epigenetics is underpinning the latest cancer research and how this can be translated into directed efforts to improve animal health and welfare.

Cadmium Levels in Tissue and Plasma as a Risk Factor for Prostate Carcinoma: a Meta-Analysis

Cadmium is a heavy metal that has been suggested to be a carcinogen by evidence. A number of published studies have investigated the association between cadmium levels and prostate cancer, but the results were inconsistent. Thus, we conducted a meta-analysis to get a precise estimate of this subject. After a careful searching and screening, a total of 11 publications containing 14 separated studies were included. Based on a random-effect model, the pooled data showed that cadmium levels of prostate tissues (standard mean difference (SMD) = 3.17, 95 % confidence interval (CI) = 0.60-5.74, P < 0.05) and plasma (SMD = 4.07, 95 % CI = 2.01-6.13, P < 0.05) were significantly higher in prostate cancer patients than those in the healthy controls. No difference of hair and nail cadmium levels between the prostate cancer cases and the controls was found. The data suggested that cadmium exposure might exert an influence on the tumorigenesis of prostate tissues. Future investigations with large sample sizes are needed to verify the results.

Self-assembly of high-nuclearity lanthanide-based nanoclusters for potential bioimaging applications

Two series of Cd-Ln and Ni-Ln clusters [Ln8Cd24L12(OAc)44(48)Cl4(0)] and [Ln8Ni6L6(OAc)24(EtOH)6(H2O)2] were constructed using a flexible ligand. The Cd-Ln clusters exhibit interesting nano-drum-like structures which allows direct visualization by TEM. Luminex MicroPlex Microspheres loaded with the Cd-Sm cluster were visualized using epifluorescence microscopy. Cytotoxicity studies on A549 and AGS cancer cell lines showed that the materials have mild to moderate cytotoxicity.

A Model of Cadmium Uptake and Transport in Caco-2 Cells

We created a physiologically substantiated kinetic model of cadmium transport and toxicity in intestinal cell model (Caco-2 cells). Transcriptome profiling of Caco-2 cells revealed high content of transporter DMT1 and ZIP14 and intensive expression of some calcium channels of the CACN family. The mathematical model describing three types of transporters, as well as intracellular cadmium binding with metallothionein and excretion through the basolateral membrane allowed us to construct cadmium uptake and transport curves that approximated the previously obtained experimental data. Using the proposed model, we determined toxic intracellular cadmium concentration leading to cell death and impairing the integrity of cell monolayer and described cadmium transport in this case.

ROS-dependent HMGA2 upregulation mediates Cd-induced proliferation in MRC-5 cells

Cadmium (Cd) is a heavy metal widely found in a number of environmental matrices, and the exposure to Cd is increasing nowadays. In this study, the role of high mobility group A2 (HMGA2) in Cd-induced proliferation was investigated in MRC-5 cells. Exposure to Cd (2μM) for 48h significantly enhanced the growth of MRC-5 cells, increased reactive oxygen species (ROS) production, and induced both mRNA and protein expression of HMGA2. Evidence for Cd-induced reduction of the number of G0/G1 phase cells and an increase in the number of cells in S phase and G2/M phase was sought by flow cytometric analysis. Western blot analysis showed that cyclin D1, cyclin B1, and cyclin E were upregulated in Cd-treated cells. Further study revealed that N-acetyl cysteine (NAC) markedly prevented Cd-induced proliferation of MRC-5 cells, ROS generation, and the increasing protein level of HMGA2. Silencing of HMGA2 gene by siRNA blocked Cd-induced cyclin D1, cyclin B1, and cyclin E expression and reduction of the number of G0/G1 phase cells. Combining, our data showed that Cd-induced ROS formation provoked HMGA2 upregulation, caused cell cycle changes, and led to cell proliferation. This suggests that HMGA2 might be an important biomarker in Cd-induced cell proliferation.

Metals and Neurodegeneration

Metals play important roles in the human body, maintaining cell structure and regulating gene expression, neurotransmission, and antioxidant response, to name a few. However, excessive metal accumulation in the nervous system may be toxic, inducing oxidative stress, disrupting mitochondrial function, and impairing the activity of numerous enzymes. Damage caused by metal accumulation may result in permanent injuries, including severe neurological disorders. Epidemiological and clinical studies have shown a strong correlation between aberrant metal exposure and a number of neurological diseases, including Alzheimer’s disease, amyotrophic lateral sclerosis, autism spectrum disorders, Guillain–Barré disease, Gulf War syndrome, Huntington’s disease, multiple sclerosis, Parkinson’s disease, and Wilson’s disease. Here, we briefly survey the literature relating to the role of metals in neurodegeneration.

Dietary exposure to cadmium and risk of breast cancer in postmenopausal women: A systematic review and meta-analysis

BACKGROUND

With tobacco smoking, diet is the main source of cadmium (Cd) exposure in the general population. The carcinogenic and estrogenic activities of Cd make it a contaminant of potential concern for hormone-dependent cancers including breast cancer. Postmenopausal women represent the most appropriate population to investigate the possible impact of exogenous factors with potential estrogenic activity on breast cancer as, after menopause, their estrogenic influence is predominant.

OBJECTIVES

We systematically reviewed available studies on the association between dietary exposure to Cd and breast cancer focusing on postmenopausal women. A meta-analysis combining the risk estimators was performed and potential sources of between studies heterogeneity were traced.

METHODS

Studies were searched from MEDLINE through 31 January 2015 and from the reference lists of relevant publications. Six eligible studies published between 2012 and 2014 were identified and relative risk estimates were extracted. Meta-rate ratio estimates (mRR) were calculated according to fixed and random-effect models. Meta-analyses were performed on the whole set of data and separate analyses were conducted after stratification for study design, geographic location, use of hormone replacement therapy (HRT), tumor estrogen receptor status (ER+ or ER-), progesterone receptor status (PGR+ or PGR-), body mass index (BMI), smoker status, zinc or iron intake.

RESULTS

No statistically significant increased risk of breast cancer was observed when all studies were combined (mRR=1.03; 95% confidence interval [CI]: 0.89-1.19). Several sources of heterogeneity and inconsistency were identified, including smoker status, HRT use, BMI, zinc and iron intake. Inconsistency was also strongly reduced when only considering ER-, PGR-, tumors subgroups from USA and from Japan. The risks were, however, not substantially modified after stratifications. No evidence of publication bias was found.

CONCLUSION

The present study does not provide support for the hypothesis that dietary exposure to Cd increases the risk of breast cancer in postmenopausal women. Misclassification in dietary Cd assessment in primary studies could have biased the results towards a finding of no association.

Combined DNA, toxicological and heavy metal analyses provides an auditing toolkit to improve pharmacovigilance of traditional Chinese medicine (TCM)

Globally, there has been an increase in the use of herbal remedies including traditional Chinese medicine (TCM). There is a perception that products are natural, safe and effectively regulated, however, regulatory agencies are hampered by a lack of a toolkit to audit ingredient lists, adulterants and constituent active compounds. Here, for the first time, a multidisciplinary approach to assessing the molecular content of 26 TCMs is described. Next generation DNA sequencing is combined with toxicological and heavy metal screening by separation techniques and mass spectrometry (MS) to provide a comprehensive audit. Genetic analysis revealed that 50% of samples contained DNA of undeclared plant or animal taxa, including an endangered species of Panthera (snow leopard). In 50% of the TCMs, an undeclared pharmaceutical agent was detected including warfarin, dexamethasone, diclofenac, cyproheptadine and paracetamol. Mass spectrometry revealed heavy metals including arsenic, lead and cadmium, one with a level of arsenic >10 times the acceptable limit. The study showed 92% of the TCMs examined were found to have some form of contamination and/or substitution. This study demonstrates that a combination of molecular methodologies can provide an effective means by which to audit complementary and alternative medicines.

Cadmium exposure and the risk of breast cancer in Chaoshan population of southeast China

Recently, there is increasing evidence indicating a link between cadmium exposure and human breast cancer. This study was aimed to explore the relationship between blood cadmium burden and the risk of breast cancer in Chaoshan women with no occupational exposure. Blood cadmium levels (BCLs) were determined in whole blood of 186 breast cancer cases and 139 controls. Basic clinical data and information of age, occupation, blood types, family cancer history, and disease history, as well as other demographic characteristics were collected from medical records. BCLs were detected by graphite-furnace atomizer absorption spectrophotometer (GFAAS). BCLs and proportions of BCLs over 3 μg/L between cases and controls were compared. The relationships between BCLs and breast cancer were explored by comparing BCL differences between/among different characteristics of investigated factors. In addition, BCLs within cases were also compared in relation to the disease clinical stages, tumor-node-metastasis (TNM) stages, and estrogen receptor (ER), progesterone receptor (PR), and Cerb-B2 expressions. The breast cancer patients had a higher median concentration of blood cadmium (2.28, interquartile range 1.57-3.15 μg/L) than the controls (1.77, 1.34-2.57 μg/L; P = 0.001). The proportion of BCLs over 3 μg/L was 2.35 times higher in the breast cancer cases than that of the controls after adjusting for age. Cadmium tends to accumulate in the human body with age and body mass index (BMI) but not associates with type of job, family history, disease history, and other investigated characters. With the increase of clinical stages and T and M stages, the BCLs in the breast cancer cases also increased. BCLs were positively associated with Cerb-B2 expression (r = 0.152, P = 0.038) but not significantly associated with ER and PR expressions. The data obtained show that cadmium concentration is significantly higher in blood of breast cancer patients in comparison to healthy controls. Cadmium seems to be a risk factor of breast cancer, and high cadmium exposure was observed in advanced stages of this disease, which indicates that it may promote the development of breast cancer.

Cadmium treatment suppresses DNA polymerase δ catalytic subunit gene expression by acting on the p53 and Sp1 regulatory axis

Cadmium (Cd) is a carcinogenic and neurotoxic environmental pollutant. Among the proposed mechanisms for Cd toxic effects, its ability to promote oxidative stress and to inhibit, in vitro, the activities of some Base Excision DNA Repair (BER) enzymes, such as hOGG1, XRCC1 and APE1, have been already established. However, the molecular mechanisms at the basis of these processes are largely unknown especially at sub-lethal doses of Cd and no information is available on the effect of Cd on the expression levels of BER enzymes. Here, we show that non-toxic treatment of neuronal cell lines, with pro-mitogenic doses of Cd, promotes a significant time- and dose-dependent down-regulation of DNA polymerase δ (POLD1) expression through a transcriptional mechanism with a modest effect on Polβ, XRCC1 and APE1. We further elucidated that the observed transcriptional repression on Polδ is acted by through competition by activated p53 on Sp1 at POLD1 promoter and by a squelching effect. We further proved the positive effect of Sp1 not only on POLD1 expression but also on Polβ, XRCC1 and APE1 expression, suggesting that Sp1 has pleiotropic effects on the whole BER pathway. Our results indicated that Cd-mediated impairment of BER pathway, besides acting on the enzymatic functions of some key proteins, is also exerted at the gene expression level of Polδ by acting on the p53-Sp1 regulatory axis. These data may explain not only the Cd-induced neurotoxic effects but also the potential carcinogenicity of this heavy metal.

Assessing potential harmful effects of CdSe quantum dots by using Drosophila melanogaster as in vivo model

Since CdSe QDs are increasingly used in medical and pharmaceutical sciences careful and systematic studies to determine their biosafety are needed. Since in vivo studies produce relevant information complementing in vitro data, we promote the use of Drosophila melanogaster as a suitable in vivo model to detect toxic and genotoxic effects associated with CdSe QD exposure. Taking into account the potential release of cadmium ions, QD effects were compared with those obtained with CdCl2. Results showed that CdSe QDs penetrate the intestinal barrier of the larvae reaching the hemolymph, interacting with hemocytes, and inducing dose/time dependent significant genotoxic effects, as determined by the comet assay. Elevated ROS production, QD biodegradation, and significant disturbance in the conserved Hsps, antioxidant and p53 genes were also observed. Overall, QD effects were milder than those induced by CdCl2 suggesting the role of Cd released ions in the observed harmful effects of Cd based QDs. To reduce the observed side-effects of Cd based QDs biocompatible coats would be required to avoid cadmium's undesirable effects.

MicroRNAs-mRNAs Expression Profile and Their Potential Role in Malignant Transformation of Human Bronchial Epithelial Cells Induced by Cadmium

Background. Our study was designed to elucidate whether there were miRNA and mRNA aberrantly expression profiles and potential role in malignant transformation of 16HBE induced by Cd. Methods. mRNA and miRNA expression profiles were determined in 35th Cd-induced 16HBE and untreated 16HBE by microarray. A series of bioinformatics analyses such as predicting targets, GO, KEGG were performed to find DEGs, coexpressing networks between miRNAs and mRNAs and its functions. Results. 498 DEGs were found. 8 Cd-responsive novel miRNAs predicted previously were identified, and 5 of them were downregulated. 214 target genes were predicted for the Cd-responsive miRNAs, many of which appeared to regulate gene networks. Target gene CCM2 was showed reciprocal effect by miRNAs. According to the combination analysis, hsa-miR-27b-3p regulated most of the mRNAs, especially upregulated expression genes. The differentially expressed miRNAs are involved in the biological processes and channels, and these GO and KEGG enrichment analyses result were significantly enriched in the Cd-responsive. Discussion. These results provided a tight link for the miRNA-mRNA integrated network and implied the role of novel miRNAs in malignant transformation of 16HBE induced by Cadmium. It is better to understand the novel molecular mechanism of cadmium-induced tumorigenesis.

Rural-urban differences in the clinico-pathologic profiles of Jamaican men with prostate cancer

Background

Prostate cancer causes the highest number of cancer-related deaths in Jamaican men. It is not known whether rural-dwelling men present with worse disease than urban-dwelling men at initial presentation. Since rural and urban-dwelling Jamaicans are predominantly of African descent and generally similar in respect of racial composition, if any significant variation in initial presentation were found, it would suggest that these are likely due to differences in awareness, access to care, and screening patterns.

Methods

The medical records of rural and urban-dwelling patients with prostate cancer were compared. Patients’ age at presentation, initial prostate-specific antigen level, digital rectal examination findings, biopsy Gleason scores and initial treatment received were compared using bivariate and logistic regression analyses.

Results

In unadjusted analyses rural-dwelling men were older compared to urban-dwelling men (72 years versus 68.5 years, p = 0.035), had higher median PSA values (22.9 ng/ml versus 18 ng/ml, p = 0.001), higher local tumour stage (65.2 % versus 34.8 % T3 disease; 73.7 % versus 26.3 % T4 disease; p = 0.005), higher mean Gleason scores (p = 0.048) and more non-curative initial treatments. Local tumour stage was the only statistically significant difference between rural and urban-dwelling men in logistic regression analysis with rural-dwelling men having a 70 % higher risk of locally-advanced disease (OR = 1.70, 95 % CI: 1.03-2.79; p = 0.038).

Conclusion

Rural-dwelling men presented with more advanced prostate cancer compared to urban-dwelling men. As both rural and urban-dwelling men are of predominant African descent it is likely that these differences are due to differences in access to care, screening practice and awareness of the disease.

Gene expression and pathway analysis of human hepatocellular carcinoma cells treated with cadmium

Cadmium (Cd) is a toxic and carcinogenic metal naturally occurring in the Earth's crust. A common route of human exposure is via diet and cadmium accumulates in the liver. The effects of Cd exposure on gene expression in human hepatocellular carcinoma (HepG2) cells were examined in this study. HepG2 cells were acutely-treated with 0.1, 0.5, or 1.0 μM Cd for 24h; or chronically-treated with 0.01, 0.05, or 0.1 μM Cd for three weeks and gene expression analysis was performed using Affymetrix GeneChip® Human Gene 1.0 ST Arrays. Acute and chronic exposures significantly altered the expression of 333 and 181 genes, respectively. The genes most upregulated by acute exposure included several metallothioneins. Downregulated genes included the monooxygenase CYP3A7, involved in drug and lipid metabolism. In contrast, CYP3A7 was upregulated by chronic Cd exposure, as was DNAJB9, an anti-apoptotic J protein. Genes downregulated following chronic exposure included the transcriptional regulator early growth response protein 1. Ingenuity Pathway Analysis revealed that the top networks altered by acute exposure were lipid metabolism, small molecule biosynthesis, cell morphology, organization, and development; while top networks altered by chronic exposure were organ morphology, cell cycle, cell signaling, and renal and urological diseases/cancer. Many of the dysregulated genes play important roles in cellular growth, proliferation, and apoptosis, and may be involved in carcinogenesis. In addition to gene expression changes, HepG2 cells treated with cadmium for 24h indicated a reduction in global levels of histone methylation and acetylation that persisted 72 h post-treatment.

Sertoli cells are the target of environmental toxicants in the testis - a mechanistic and therapeutic insight

INTRODUCTION

Sertoli cells support germ cell development in the testis via an elaborate network of cell junctions that confers structural, communicating, and signaling support. However, Sertoli cell junctions and cytoskeletons are the target of environmental toxicants. Because germ cells rely on Sertoli cells for the provision of structural/functional/nutritional support, exposure of males to toxicants leads to germ cell exfoliation due to Sertoli cell injuries. Interestingly, the molecular mechanism(s) by which toxicants induce cytoskeletal disruption that leads to germ cell exfoliation is unclear, until recent years, which are discussed herein. This information can possibly be used to therapeutically manage toxicant-induced infertility/subfertility in human males.

AREAS COVERED

In this review, we provide a brief update on the use of Sertoli cell system developed for rodents and humans in vitro, which can be deployed in any research laboratory with minimal upfront setup costs. These systems can be used to collect reliable data applicable to studies in vivo. We also discuss the latest findings on the mechanisms by which toxicants induce Sertoli cell injury, in particular cytoskeletal disruption. We also identify candidate molecules that are likely targets of toxicants.

EXPERT OPINION

We provide two hypothetical models delineating the mechanism by which toxicants induce germ cell exfoliation and blood-testis barrier disruption. We also discuss molecules that are the targets of toxicants as therapeutic candidates.

The effect of metallothionein 2A core promoter region single-nucleotide polymorphism on accumulation of toxic metals in sinonasal inverted papilloma tissues

Metallothioneins (MTs) are intracellular thiol-rich heavy metal-binding proteins which join trace metal ions protecting cells against heavy metal toxicity and regulate metal distribution and donation to various enzymes and transcription factors. The goal of this study was to identify the -5 A/G (rs28366003) single-nucleotide polymorphism (SNP) in the core promoter region of the MT2A gene, and to investigate its effect on allele-specific gene expression and Cd, Zn, Cu and Ni content in sinonasal inverted papilloma tissue (IP), with non-cancerous sinonasal mucosa (NCM) as a control. The MT2A promoter region -5 A/G SNP was identified by restriction fragment length polymorphism using 117 IP and 132 NCM. MT2A gene analysis was performed by quantitative real-time PCR. Metal levels were analyzed by flame atomic absorption spectrometry. The frequency of A allele carriage was 99.2% and 100% in IP and NCM, respectively. The G allele carriage was detected in 23.9% of IP and in 12.1% of the NCM samples. As a result, a significant association of -5 A/G SNP in MT2A gene with mRNA expression in both groups was determined. A significant association was identified between the -5 A/G SNP in the MT2A gene with mRNA expression in both groups. A highly significant association was detected between the rs28366003 genotype and Cd and Zn content in IP. Furthermore, significant differences were identified between A/A and A/G genotype with regard to the type of metal contaminant. The Spearman rank correlation results showed the MT2A gene expression and both Cd and Cu levels were negatively correlated. The results obtained in this study suggest that the -5 A/G SNP in the MT2A gene may have an effect on allele-specific gene expression and toxic metal accumulation in sinonasal inverted papilloma.

Cadmium-containing carbonic anhydrase CDCA1 in marine diatom Thalassiosira weissflogii

The Carbon Concentration Mechanism (CCM) allows phytoplakton species to accumulate the dissolved inorganic carbon (DIC) necessary for an efficient photosynthesis even under carbon dioxide limitation. In this mechanism of primary importance for diatoms, a key role is played by carbonic anhydrase (CA) enzymes which catalyze the reversible hydration of CO2, thus taking part in the acquisition of inorganic carbon for photosynthesis. A novel CA, named CDCA1, has been recently discovered in the marine diatom Thalassiosira weissflogii. CDCA1 is a cambialistic enzyme since it naturally uses Cd2+ as catalytic metal ion, but if necessary can spontaneously exchange Cd2+ to Zn2+. Here, the biochemical and structural features of CDCA1 enzyme will be presented together with its putative biotechnological applications for the detection of metal ions in seawaters.