Metallothionein - immunohistochemical cancer biomarker: a meta-analysis

Gleason Score-related MT1L as biomarker for prognosis in prostate adenocarcinoma and contribute to tumor progression in vitro

BACKGROUND

The Gleason Score is well correlated with biological behavior and prognosis in prostate adenocarcinoma (PRAD). This study was derived to determine the clinical significance and function of Gleason-Score-related genes in PRAD.

METHODS

RNA-sequencing profiles and clinical data were extracted from the The Cancer Genome Atlas PRAD database. The Gleason-Score-related genes were screened out by the Jonckheere-Terpstra rank-based test. The "limma" R package was performed for differentially expressed genes. Next, a Kaplan-Meier survival analysis was performed. Correlation MT1L expression levels with tumor stage, non-tumor tissue stage, radiation therapy, and residual tumor were analyzed. Further, MT1L expression was detected in PRAD cell lines by reverse transcription-quantitative polymerase chain reaction assay. Overexpression of MT1L was constructed and used for cell count kit-8, flow cytometric assay, transwell assay, and wound-healing assay.

RESULTS

Survival analysis showed 15 Gleason-Score-related genes as prognostic biomarkers in PRAD. The high-frequency deletion of MT1L was verified in PRAD. Furthermore, MT1L expression was decreased in PRAD cell lines than RWPE-1 cells, and overexpression of MT1L repressed cell proliferation and migration, and induced apoptosis in PC-3 cells.

CONCLUSION

Gleason-Score-related MT1L may serve as a biomarker of poor prognostic biomarker in PRAD. In addition, MT1L plays a tumor suppressor in PRAD progression, which is beneficial for PRAD diagnosis and treatment research.

An Assessment of MT1A (rs11076161), MT2A (rs28366003) and MT1L (rs10636) Gene Polymorphisms and MT2 Concentration in Women with Endometrial Pathologies

Several studies have indicated a relationship between metallothionein (MT) polymorphisms and the development of different pathologies, including neoplastic diseases. However, no studies thus far have been conducted on the influence of MT polymorphisms and the development of endometrial lesions, including endometrial cancer. This study included 140 patients with normal endometrial tissue, endometrial polyps, uterine myomas and endometrial cancer. The tissue MT2 concentration was determined using the ELISA method. MT1A, MT2A and MT1L polymorphisms were analyzed using TaqMan real-time PCR genotyping assays. We found no statistical difference between the tissue MT2 concentration in patients with EC vs. benign endometrium (p = 0.579). However, tissue MT2 concentration was significantly different between uterine fibromas and normal endometrial tissue samples (p = 0.019). Menopause status did not influence the tissue MT2 concentration (p = 0.282). There were no significant associations between the prevalence of MT1A, MT2A and MT1L polymorphisms and MT2 concentration. The age, menopausal status, and diabetes status of patients were identified as EC risk factors.

Zinc in Prostate Health and Disease: A Mini Review

Introduction-With the high global prevalence of prostate cancer and associated mortalities, it is important to enhance current clinical practices for better prostate cancer outcomes. The current review is towards understanding the value of Zn towards this mission. Method-General information on Zn in biology and multiple aspects of Zn involvement in prostate health and disease were referred to in PubMed. Results-The most influential feature of Zn towards prostate health is its ability to retain sufficient citrate levels for a healthy prostate. Zn deficiencies were recorded in serum, hair, and prostate tissue of men with prostate cancer compared to non-cancer controls. Zn gut absorption, albumin binding, and storage compete with various factors. There are multiple associations of Zn cellular influx and efflux transporters, Zn finger proteins, matrix metalloproteinases, and Zn signaling with prostate cancer outcomes. Such Zn marker variations associated with prostate cancer recorded from biological matrices may improve algorithms for prostate cancer screening, prognosis, and management when coupled with standard clinical practices. Discussion-The influence of Zn in prostatic health and disease is multidimensional, therefore more personalized Zn requirements may be beneficial. Several opportunities exist to utilize and improve understanding of Zn associations with prostate health and disease.

Comparative cisplatin reactivity towards human Zn7-metallothionein-2 and MTF-1 zinc fingers: potential implications in anticancer drug resistance

Cis-diamminedichloroplatinum(II) (cisplatin) is a widely used metal-based chemotherapeutic drug for the treatment of cancers. However, intrinsic and acquired drug resistance limit the efficacy of cisplatin-based treatments. Increased production of intracellular thiol-rich molecules, in particular metallothioneins (MTs), which form stable coordination complexes with the electrophilic cisplatin, results in cisplatin sequestration leading to pre-target resistance. MT-1/-2 are overexpressed in cancer cells, and their expression is controlled by the metal response element (MRE)-binding transcription factor-1 (MTF-1), featuring six Cys2His2-type zinc fingers which, upon zinc metalation, recognize specific MRE sequences in the promoter region of MT genes triggering their expression. Cisplatin can efficiently react with protein metal binding sites featuring nucleophilic cysteine and/or histidine residues, including MTs and zinc fingers proteins, but the preferential reactivity towards specific targets with competing binding sites cannot be easily predicted. In this work, by in vitro competition reactions, we investigated the thermodynamic and kinetic preferential reactivity of cisplatin towards human Zn7MT-2, each of the six MTF-1 zinc fingers, and the entire human MTF-1 zinc finger domain. By spectroscopic, spectrometric, and electrophoretic mobility shift assays (EMSA), we demonstrated that cisplatin preferentially reacts with Zn7MT-2 to form Cys4-Pt(II) complexes, resulting in zinc release from MT-2. Zinc transfer from MT-2 to the MTF-1 triggers MTF-1 metalation, activation, and binding to target MRE sequences, as demonstrated by EMSA with DNA oligonucleotides. The cisplatin-dependent MT-mediated MTF-1 activation leading to apo-MT overexpression potentially establishes one of the molecular mechanisms underlying the development and potentiation of MT-mediated pre-target resistance.

Cancer suppression by ferroptosis and its role in digestive system tumors

Cancer is the second leading cause of death worldwide, and digestive system tumors remain the leading malignancy in China, seriously endangering national health and imposing a huge economic burden. Ferroptosis is a form of cell death characterized by increased intracellular reduced iron and accumulated lipid peroxide. Recent studies have revealed that ferroptosis is closely related to the occurrence and treatment of cancer. Therefore, this paper reviews the studies on ferroptosis and cancer to explore the potential of ferroptosis in the treatment of malignant tumors, especially digestive system tumors, and to provide a new direction for developing treatment options.

Metallothionein 2A with Antioxidant and Antitumor Activity Is Upregulated by Caffeic Acid Phenethyl Ester in Human Bladder Carcinoma Cells

Functions of metallothionein 2A (MT2A) in bladder cancer have not been extensively explored even though metallothioneins are regarded as modulators in several biological regulations including oxidation and cancerous development. We evaluated MT2A in bladder carcinoma cells in terms of the mechanisms of regulation and the underlying functions. MT2A overexpression not only downregulated endogenous ROS but also blocked ROS induced by H₂O₂. We used the annexin V-FITC apoptosis assay to determine the modulation of H₂O₂-induced cell apoptosis by MT2A expression. Results of immunoblot and reporter assays indicated that caffeic acid phenethyl ester (CAPE) treatment induced MT2A and heme oxygenase-1 (HO-1) expressions; moreover, the involvement of CAPE in either upregulation of the HO-1 expression or downregulation of endogenous ROS is MT2A dependent in bladder carcinoma cells. Knockdown of MT2A increased invasion and cell growth in vitro and in vivo, whereas ectopic overexpression of MT2A had the reverse effect in bladder carcinoma cells. Unlike bladder cancer tissues, the real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) analysis showed a significant level of MT2A mRNA in the normal bladder tissues. Collectively, our results indicated that MT2A is acting as an antioxidant and also a tumor suppressor in human bladder carcinoma cells.

The Critical Role of Ferroptosis in Hepatocellular Carcinoma

Liver cancer is the sixth most frequently diagnosed cancer and the third dominant cause of cancer death worldwide. Ferroptosis is characterized as an iron-dependent form of regulated cell death, with accumulation of lipid peroxides to lethal amounts. Evidences have showed that ferroptosis is closely associated with HCC, but the mechanisms are still poorly understood. In this review, we mainly summarize the roles of several typical molecules as well as radiotherapy in regulating the ferroptosis process in HCC. Chances are that this review may help address specific issues in the treatment of HCC.

Towards a global investigation of transcriptomic signatures through co-expression networks and pathway knowledge for the identification of disease mechanisms

We attempt to address a key question in the joint analysis of transcriptomic data: can we correlate the patterns we observe in transcriptomic datasets to known interactions and pathway knowledge to broaden our understanding of disease pathophysiology? We present a systematic approach that sheds light on the patterns observed in hundreds of transcriptomic datasets from over sixty indications by using pathways and molecular interactions as a template. Our analysis employs transcriptomic datasets to construct dozens of disease specific co-expression networks, alongside a human protein-protein interactome network. Leveraging the interoperability between these two network templates, we explore patterns both common and particular to these diseases on three different levels. Firstly, at the node-level, we identify most and least common proteins across diseases and evaluate their consistency against the interactome as a proxy for their prevalence in the scientific literature. Secondly, we overlay both network templates to analyze common correlations and interactions across diseases at the edge-level. Thirdly, we explore the similarity between patterns observed at the disease-level and pathway knowledge to identify signatures associated with specific diseases and indication areas. Finally, we present a case scenario in schizophrenia, where we show how our approach can be used to investigate disease pathophysiology.

Expression profiles of metallothionein-I/II and megalin/LRP-2 in uterine cervical squamous lesions

Metallothioneins (MTs) are phylogenetically old cysteine-rich proteins, which are implicated in a variety of physiological and pathological processes. Their growth-regulating, anti-apoptotic and anti-inflammatory functions have been attributed not only to intracellular free radical scavenging and to zinc and copper regulation but also to the ability of secreted MT to bind on surface lipoprotein receptor-megalin/LRP2, which enables the endocytosis of MT-I/II and a wide range of other functionally distinct ligands. In the present study, we analysed the expression pattern of both proteins in 55 cases of premalignant transformation of cervical squamous cells, i.e. in low- and high-grade squamous intraepithelial lesion (LSIL and HSIL). The data showed that in LSIL (cervical intraepithelial neoplasia CIN1; N = 25) MTs were present only in basal and parabasal cells and that megalin was only weakly expressed. In HSIL (CIN2; N = 15 and CIN 3/carcinoma in situ; N = 15), however, overexpression and co-localization of MT with megalin were found in the entire hyperplastic epithelium. Moreover, megalin immunoreactivity appeared on the glandular epithelium and vascular endothelium, as well as on lymphatic cells in stroma. Besides, multiple megalin-positive cells expressed phosphorylated Akt1, implying that MT- and/or megalin-dependent prosurvival signal transduction pathways might contribute to the development of severe cervical dysplasia. The data emphasize the diagnostic power of combined MT/megalin analysis in pre-cancer screening.

Serum copper, zinc and metallothionein serve as potential biomarkers for hepatocellular carcinoma

BACKGROUND

Copper (Cu) and zinc (Zn) are essential nutrients and cofactors of enzymatic reactions with their binding partner. Metallothionein (MT) plays an important role in protecting against heavy metals and oxidative injury, however it may also portend drug resistance and a worse prognosis for hepatocellular carcinoma (HCC) patients. The aim of this study was to determine the amount of Cu, Zn, Cu/Zn and MT in evaluating a group of patients with HCC, including those treated with lenvatinib.

METHODS

We enrolled 175 patients with HCC (139 men, 36 women; mean age 71.1 years; hepatitis C virus n = 85, hepatitis B virus n = 19, hepatitis C virus and hepatitis B virus n = 2, non-alcoholic steatohepatitis n = 39, alcohol n = 25, others n = 5; Child-Pugh A n = 141, Child-Pugh B n = 30, Child-Pugh C n = 4; Barcelona clinic liver cancer (BCLC) stage 0 n = 38, stage A n = 56, stage B n = 39, stage C n = 38, stage D n = 4). We evaluated the associations between Cu, Zn and MT. The study outcome was liver cancer-specific survival. Moreover, we treated 12 HCC patients with lenvatinib and investigated the changes in MT during lenvatinib therapy.

RESULTS

The serum level of Cu was positively correlated with alanine aminotransferase and the BCLC stage. The serum level of Zn decreased concordant with liver disease progression. Patients with a Cu/Zn ratio≥0.999 had significantly improved rates of survival when compared to patients with a Cu/Zn ratio<0.999 (45.3 vs. 30.1 months, p<0.001). MT was significantly correlated with the Cu/Zn ratio and increased after the administration of lenvatinib. Using multivariate Cox regression analyses, it was determined that the Cu/Zn ratio (hazard ratio [HR]: 1.442, p = 0.008), alpha-fetoprotein (HR: 1.000, p<0.001) and BCLC stage (HR: 2.087, p<0.001) were independent predictors of survival.

CONCLUSIONS

The Cu/Zn ratio could serve as a useful predictive marker for survival in cases of HCC. MT levels increased in HCC patients receiving lenvatinib therapy, and maybe a predictor of reduced survival.

Microalgal Metallothioneins and Phytochelatins and Their Potential Use in Bioremediation

The persistence of heavy metals (HMs) in the environment causes adverse effects to all living organisms; HMs accumulate along the food chain affecting different levels of biological organizations, from cells to tissues. HMs enter cells through transporter proteins and can bind to enzymes and nucleic acids interfering with their functioning. Strategies used by microalgae to minimize HM toxicity include the biosynthesis of metal-binding peptides that chelate metal cations inhibiting their activity. Metal-binding peptides include genetically encoded metallothioneins (MTs) and enzymatically produced phytochelatins (PCs). A number of techniques, including genetic engineering, focus on increasing the biosynthesis of MTs and PCs in microalgae. The present review reports the current knowledge on microalgal MTs and PCs and describes the state of art of their use for HM bioremediation and other putative biotechnological applications, also emphasizing on techniques aimed at increasing the cellular concentrations of MTs and PCs. In spite of the broad metabolic and chemical diversity of microalgae that are currently receiving increasing attention by biotechnological research, knowledge on MTs and PCs from these organisms is still limited to date.

Metallothionein isoforms as double agents - Their roles in carcinogenesis, cancer progression and chemoresistance

Metallothioneins (MTs) are small cysteine-rich intracellular proteins with four major isoforms identified in mammals, designated MT-1 through MT-4. The best known biological functions of MTs are their ability to bind and sequester metal ions as well as their active role in redox homeostasis. Despite these protective roles, numerous studies have demonstrated that changes in MT expression could be associated with the process of carcinogenesis and participation in cell differentiation, proliferation, migration, and angiogenesis. Hence, MTs have the role of double agents, i.e., working with and against cancer. In view of their rich biochemical properties, it is not surprising that MTs participate in the emergence of chemoresistance in tumor cells. Many studies have demonstrated that MT overexpression is involved in the acquisition of resistance to anticancer drugs including cisplatin, anthracyclines, tyrosine kinase inhibitors and mitomycin. The evidence is gradually increasing for a cellular switch in MT functions, showing that they indeed have two faces: protector and saboteur. Initially, MTs display anti-oncogenic and protective roles; however, once the oncogenic process was launched, MTs are utilized by cancer cells for progression, survival, and contribution to chemoresistance. The duality of MTs can serve as a potential prognostic/diagnostic biomarker and can therefore pave the way towards the development of new cancer treatment strategies. Herein, we review and discuss MTs as tumor disease markers and describe their role in chemoresistance to distinct anticancer drugs.

The Expression Profile and Prognostic Significance of Metallothionein Genes in Colorectal Cancer

Colorectal cancer (CRC) is a heterogeneous disease resulting from the combined influence of many genetic factors. This complexity has caused the molecular characterization of CRC to remain uncharacterized, with a lack of clear gene markers associated with CRC and the prognosis of this disease. Thus, highly sensitive tumor markers for the detection of CRC are the most essential determinants of survival. In this study, we examined the simultaneous downregulation of the mRNA levels of six metallothionein (MT) genes in CRC cell lines and public CRC datasets for the first time. In addition, we detected downregulation of these six MT mRNAs’ levels in 30 pairs of tumor (T) and adjacent non-tumor (N) CRC specimens. In order to understand the potential prognostic relevance of these six MT genes and CRC, we presented a four-gene signature to evaluate the prognosis of CRC patients. Further discovery suggested that the four-gene signature (MT1F, MT1G, MT1L, and MT1X) predicted survival better than any combination of two-, three-, four-, five-, or six-gene models. In conclusion, this study is the first to report that simultaneous downregulation of six MT mRNAs’ levels in CRC patients, and their aberrant expression together, accurately predicted CRC patients’ outcomes.

Cutaneous Malignant Melanoma and Targeted Therapy Based on the Biomarkers

Malignant melanoma is the most aggressive form of cutaneous malignancy. It accounts for more than 75% of cancer-related deaths among cutaneous malignancies. It accounts for <5% of cutaneous malignancy. Numerous biomarkers are used in malignant melanoma with varying clinical applications, including diagnostic purposes, prognosis, therapeutic purpose, and targeted therapy against melanoma. Systemic chemotherapy in malignant melanoma has little benefit compared to immunotherapy and targeted therapy. The observed overall survival with systemic chemotherapy is much less compared with targeted therapy in advanced or metastatic melanoma. Various targeted therapies are currently used in melanoma treatment including BRAF inhibitors such as vemurafenib and dabrafenib; MEK inhibitors such as trametinib; anti-CTLA-4 antibodies such as ipilimumab; and anti-programmed cell death 1 antibodies such as nivolumab, pembrolizumab, and pidilizumab. This study discusses the role of biomarkers and targeted therapies based on the biomarker.

A case-control study of Metallothionein-1 expression in breast cancer and breast fibroadenoma

The overexpression of Metallothionein-1 (MT-1) may play an important role in breast cancer; however, few studies have compared MT-1 expression between breast cancer and fibroadenoma. A cross-sectional controlled study was performed in 66 premenopausal women, aged 20–49 years, who had been histologically diagnosed with breast fibroadenoma or breast cancer. The patients were divided into two groups: group A, control (fibroadenoma, n = 36) and group B, study (breast cancer, n = 30). Immunohistochemistry was performed on tissue samples of fibroadenoma and breast cancer patients to evaluate the expression of metallothionein using an anti-MT-1 polyclonal antibody (rabbit polyclonal anti-metallothionein-Catalog Number biorbyt-orb11042) at a dilution of 1:100. The data were analyzed using NOVA (p < 0.05). Microscopic analysis showed a higher concentration of anti-MT-1-stained nuclei in breast cancer tissues than in fibroadenoma tissues. The mean proportion of cells with anti-MT-1-stained nuclei was 26.93% and 9.10%, respectively, in the study and control groups (p < 0.001). Histological grade 3 tumors showed a significantly higher MT-1 expression than hitological grade 1 (p < 0.05), while breast tumors negative for estrogen-, progesterone- and HER2- receptors had a significantly higher MT-1 expression than positive breast tumors positive for these parameters (p < 0.05). MT-1 protein in women of reproductive age was significantly higher in breast cancer than in fibroadenoma in this study. Furthermore, there was higher MT-1 immunoreactivity in more aggressive tumors.

Metallothionein 3 Is a Hypoxia-Upregulated Oncogene Enhancing Cell Invasion and Tumorigenesis in Human Bladder Carcinoma Cells

Metallothioneins have been viewed as modulators in a number of biological regulations regarding cancerous development; however, the function of metallothionein 3 (MT3) in bladder cancer is unexplored. We determined the regulatory mechanisms and potential function of MT3 in bladder carcinoma cells. Real-Time Reverse Transcriptase-Polymerase Chain Reaction (RT-qPCR) assays revealed that TSGH-8301 cells expressed more MT3 levels than RT-4, HT1376, and T24 cells. Immunoblot and RT-qPCR assays showed that arsenic (AS₂O₃) treatments enhanced the gene expression of MT3. Hypoxia induced HIF-1α, HIF-2α, and MT3 expression; furthermore, HIF-2α-knockdown attenuated hypoxic activation on MT3 expression. Ectopic overexpression of MT3 increased cell proliferation, invasion, and tumorigenesis significantly in T24 and HT1376 cells in vitro and in vivo; however, MT3-knockdown in TSGH-8301 cells had the reverse effect. Moreover, knockdown of MT3 enhanced arsenic-induced apoptosis determined by the Annexin V-FITC apoptosis assay. MT3-overexpression downregulated the gene expressions of N-myc downstream regulated gene 1 (NDRG1), N-myc downstream regulated gene 2 (NDRG2), and the mammary serine protease inhibitor (MASPIN) in HT1376 and T24 cells, whereas MT3-knockdown in TSGH-8301 cells had the opposite effect. The experiments indicated that MT3 is an arsenic- and hypoxia-upregulated oncogene that promotes cell growth and invasion of bladder carcinoma cells via downregulation of NDRG1, NDRG2, and MASPIN expressions.

Metallothioneins may be a potential prognostic biomarker for tumors: A Prisma-compliant meta-analysis

BACKGROUND

Metallothioneins (MTs) were reported to be associated with many kinds of tumors' prognosis, although MTs expression varied greatly among tumors. To assess the prognostic value of Metallothioneins (MTs) in different kinds of tumors, comprehensive literature search was conducted to perform a meta-analysis.

METHODS

Eligible studies were identified by PubMed, MEDLINE, Web of Science (WOS), the Cochrane Library of Systematic Reviews, EMBASE, China National Knowledge Infrastructure (CNKI), WANFANG database and SinoMed database up to December 2017, which was designed to assess the prognostic value of MTs in different kinds of tumors. The main endpoint events were overall survival (OS) and disease-free survival (DFS). Hazard ratios (HRs) and its variance were retrieved from the original studies directly or calculated using Engauge Digitizer version 4.1. Random or fixed effects model meta-analysis was employed depending on the heterogeneity. Publication bias was evaluated by funnel plots, Begg and Egger tests.

RESULTS

A total of 22 studies were enrolled in this meta-analysis, including 2843 tumor tissues (1517 were MTs negative/low, and 1326 were MTs high). Results showed that there was significant association between MTs expression and tumors' OS (HR = 1.60; 95%CI 1.34∼1.92, P < .00001). Subgroup analysis showed that high level of MTs expression was associated with prolonged OS in liver cancer (HR = 0.65, 95%CI 0.48∼0.89, P = .007), but it was on the contrary in the tumor of ovary (HR = 1.47, 95%CI 1.01∼2.14, P = .04), bladder (HR = 1.71, 95%CI 1.21∼2.42, P = .002), intestine (HR = 3.13, 95%CI 1.97∼4.97, P < .00001), kidney (HR = 3.31, 95%CI 1.61∼6.79, P = .001). However, there was no significant association between MTs expression and OS in breast (HR = 1.02, 95%CI 0.69∼1.51, P = .93).

CONCLUSIONS

MTs could be taken as a potential prognostic biomarker for tumors, and uniqueness of MTs prognostic value in liver cancer deserved further study.

Expression of Metallothionein after Administration of Aspirin, Vitamin C or Zinc Supplement in the DMH Induced Colon Carcinoma in Rat

Background:

Chemoprevention refers to the use of specificnatural or synthetic chemical agents to suppress the development and progression to carcinoma. The purpose of this study was to assess the effect of aspirin, vitamin C or zinc on the metallothionein (MT) mRNA gene expression as well as MT protein content byimmunohistochemistry andradioimmunoassay (RIA) in 1, 2-dimethyl hydrazine (DMH) induced cancerous colonic tissuein rats.

Methods:

Rats were randomly divided into three groups, group 1 (aspirin), group 2 (vitamin C) group 3 (zinc), each of which was further sub divided into two groups and given subcutaneous injections of DMH (30 mg/kg body weight) twice a week for 3 months and sacrificed at either 4 months (A-precancer model) or at 6 months (B-cancer model). The control groups were administered 0.5 ml saline subcutaneously. All the 3 groups were simultaneouslyadministered aspirin, vitamin Cor zinc supplement respectively from the beginning till the end of the study.

Results:

It was observed that rats co-treated with aspirin, vitamin C or zinc resulted in a significant increase in the colonic MT mRNA expression in the precancer and cancer model as compared to the saline only controls. MT protein expression showed a 60%, 64% and 78% immunopositivity in the co-treated groups respectively. The mean MT content in the precancer and the cancer model was restored to near normal levels in all the three co-treated groups.

Conclusion:

These results suggest that co-administration of aspirin, vitamin C or zinc resulted in a significant increase in MT mRNA gene expression, MT protein expression and MT protein content which could possibly be one of the reasons for a chemo protective effect against progression to colonic cancer in a chemically induced DMH model in rat. Zinc supplement had a greater effect on metallothionein expression than aspirin or vitamin C.

Differential metallothionein expression in oral lichen planus and amalgam-associated oral lichenoid lesions

Background

Oral lichen planus (OLP) is a chronic inflammatory disease mediated by T cells, which manifests as reticular (white) or erosive (red) lesions, that are eventually painful. Oral lichenoid lesion (OLL) are distinguished from OLP by the presence of precipitating factors. The aim of this study was to evaluate whether the presence of metallothionein, which is involved in anti-apoptotic pathways and the anti-oxidative response, could serve as a differential diagnostic for OLP and OLL.

Material and Methods

We evaluated the expression of metallothionein in 40 cases of OLP and 20 cases of OLL using immunohistochemistry.

Results and Conclusions

White OLP has higher concentrations of metallothionein than red OLP in basal and parabasal layers. Moreover, metallothionein was more frequently observed in the cytoplasm and nuclei of basal cells in OLP patients compared to the same regions of OLL cases. Metallothionein levels are related to OLP severity and may contribute to a differential diagnosis between OLP and OLL.

Key words:Oral lichen planus, oral lichenoid lesions, autoimmune disorders, metallothionein, immunohistochemistry.

Expression and immunolocalization of metallothioneins MT1, MT2 and MT3 in rat nephron

Rodent kidneys exhibit three isoforms of metallothioneins (MTs), MT1, MT2 and MT3, with poorly characterized localization along the nephron. Here we studied in adult male Wistar rats the renal expression of MTs mRNA by end-point RT-PCR and MT proteins by immunochemical methods The expression pattern of MT1 mRNA was cortex (CO)>outer stripe (OS)=inner stripe (IS)=inner medulla (IM), of MT2 mRNA was IM>CO>IS=OS, and of MT3 mRNA was IM>CO=OS=IM. MT1/2-antibody stained with heterogeneous intensity the cell cytoplasm and nuclei in proximal tubule (PT) and thin ascending limb, whereas MT3-antibody stained weakly the cell cytoplasm in various cortical tubules and strongly the nuclei in all nephron segments. However, the isolated nuclei exhibited an absence of MT1/2 and presence of MT3 protein. In MT1/2-positive PT cells, the intracellular staining appeared diffuse or bipolar, but the isolated brush-border, basolateral and endosomal membranes were devoid of MT1/2 proteins. In the lumen of some PT profiles, the heterogeneously sized MT1/2-rich vesicles were observed, with the limiting membrane positive for NHE3, but negative for V-ATPase, CAIV, and megalin, whereas their interior was positive for CAII and negative for cytoskeleton. They seem to be pinched off from the luminal membrane of MT1/2-rich cells, as also indicated by transmission electron microscopy. We conclude that in male rats, MTs are heterogeneously abundant in the cell cytoplasm and/or nuclei along the nephron. The MT1/2-rich vesicles in the tubule lumen may represent a source of urine MT and membranous material, whereas MT3 in nuclei may handle zink and locally-produced reactive oxygen species.

Comparative gene expression profiling of human metallothionein-3 up-regulation in neuroblastoma cells and its impact on susceptibility to cisplatin

Human metallothionein-3 (hMT-3), also known as growth inhibitory factor, is predominantly expressed in the central nervous system. hMT-3 is presumed to participate in the processes of heavy metal detoxification, regulation of metabolism and protection against oxidative damage of free radicals in the central nervous system; thus, it could play important neuromodulatory and neuroprotective roles. However, the primary functions of hMT-3 and the mechanism underlying its multiple functions in neuroblastoma have not been elucidated so far. First, we confirmed relatively high expression of hMT-3 encoding mRNA in biopsies (n = 23) from high-risk neuroblastoma subjects. Therefore, we focused on investigation of the impact of hMT-3 up-regulation in N-Myc amplifying neuroblastoma cells. The differentially up-regulated genes involved in biological pathways related to cellular senescence and cell cycle were identified using electrochemical microarray with consequent bioinformatic processing. Further, as experimental verification of microarray data, the cytotoxicity of the cisplatin (CDDP) was examined in hMT-3 and mock cells by MTT and clonogenic assays. Overall, our data strongly suggest that up-regulation of hMT-3 positively correlates with the genes involved in oncogene-induced senescence (CDKN2B and ANAPC5) or apoptosis (CASP4). Moreover, we identified a significant increase in chemoresistance to cisplatin (CDDP) due to hMT-3 up-regulation (24IC₅₀: 7.5 vs. 19.8 μg/ml), indicating its multipurpose biological significance.

An insight into the complex roles of metallothioneins in malignant diseases with emphasis on (sub)isoforms/isoforms and epigenetics phenomena

Metallothioneins (MTs) belong to a group of small cysteine-rich proteins that are ubiquitous throughout all kingdoms. The main function of MTs is scavenging of free radicals and detoxification and homeostating of heavy metals. In humans, 16 genes localized on chromosome 16 have been identified to encode four MT isoforms labelled by numbers (MT-1-MT-4). MT-2, MT-3 and MT-4 proteins are encoded by a single gene. MT-1 comprises many (sub)isoforms. The known active MT-1 genes are MT-1A, -1B, -1E, -1F, -1G, -1H, -1M and -1X. The rest of the MT-1 genes (MT-1C, -1D, -1I, -1J and -1L) are pseudogenes. The expression and localization of individual MT (sub)isoforms and pseudogenes vary at intra-cellular level and in individual tissues. Changes in MT expression are associated with the process of carcinogenesis of various types of human malignancies, or with a more aggressive phenotype and therapeutic resistance. Hence, MT (sub)isoform profiling status could be utilized for diagnostics and therapy of tumour diseases. This review aims on a comprehensive summary of methods for analysis of MTs at (sub)isoforms levels, their expression in single tumour diseases and strategies how this knowledge can be utilized in anticancer therapy.

Metallothionein 1G promotes the differentiation of HT-29 human colorectal cancer cells

Metallothioneins (MTs) are a family of low- molecular-weight, cysteine-rich proteins involved in zinc and redox metabolism, that are epigenetically downregulated during colorectal cancer (CRC) progression, but may be re-induced with a variety of agents. Since loss of MT expression is associated with a worse prognosis, in the present study we investigated the effects of overexpression of the most significantly downregulated isoform in CRC, namely MT1G, on the HT-29 cell line. Overexpression of MT1G resulted in xenograft tumors with an aberrant morphology, characterized by an evident increase in mucin-containing cells that were identified as goblet cells under electron microscopy. Immunohistochemical detection of CDX2 and cytokeratin 20 was also increased, as were goblet-cell and enterocyte-specific genes by qRT-PCR. Microarray analysis of gene expression confirmed the alteration of several differentiation signaling pathways, including the Notch pathway. Using sodium butyrate and post-confluent growth as inducers of differentiation, we demonstrated that MT1G does indeed play a functional role in promoting goblet over enterocyte differentiation in vitro. Labile zinc is also induced upon differentiation of CRC cells, functionally contributing to enterocyte over goblet differentiation, as revealed using zinc-specific chelating agents. Overall, our results uncover a new tumor-suppressor activity of MT1G in promoting the differentiation of at least some CRC tumors, and implicate MTs and zinc signaling as new players in colorectal differentiation. This further contributes to the hypothesis that re-induction of MTs may have therapeutic value by diminishing the aggressiveness of CRC tumors.

Metallothionein-1G facilitates sorafenib resistance through inhibition of ferroptosis

Hepatocellular carcinoma (HCC) is a major cause of cancer-related death worldwide and currently has the fastest rising incidence of all cancers. Sorafenib was originally identified as an inhibitor of multiple oncogenic kinases and remains the only approved systemic therapy for advanced HCC. However, acquired resistance to sorafenib has been found in HCC patients, which results in poor prognosis. Here, we show that metallothionein (MT)-1G is a critical regulator and promising therapeutic target of sorafenib resistance in human HCC cells. The expression of MT-1G messenger RNA and protein is remarkably induced by sorafenib but not other clinically relevant kinase inhibitors (e.g., erlotinib, gefitinib, tivantinib, vemurafenib, selumetinib, imatinib, masitinib, and ponatinib). Activation of the transcription factor nuclear factor erythroid 2-related factor 2, but not p53 and hypoxia-inducible factor 1-alpha, is essential for induction of MT-1G expression following sorafenib treatment. Importantly, genetic and pharmacological inhibition of MT-1G enhances the anticancer activity of sorafenib in vitro and in tumor xenograft models. The molecular mechanisms underlying the action of MT-1G in sorafenib resistance involve the inhibition of ferroptosis, a novel form of regulated cell death. Knockdown of MT-1G by RNA interference increases glutathione depletion and lipid peroxidation, which contributes to sorafenib-induced ferroptosis.

CONCLUSION

These findings demonstrate a novel molecular mechanism of sorafenib resistance and suggest that MT-1G is a new regulator of ferroptosis in HCC cells. (Hepatology 2016;64:488-500).

Does the Serum Metallothionein Level Reflect the Stage of Testicular Germ Cell Tumor?

Increased levels of metallothionein (MT) have recently been found in the blood serum of men with newly diagnosed testicular germ cell tumors (TGCT). In light of previously published results, the aim of this study was to investigate the difference in serum MT levels among patients with different stages of TGCT and compare MT with commonly used markers (α-fetoprotein, β-human chorionic gonadotropin and lactate dehydrogenase). The concentration of total MT was determined in the serum of 25 men with TGCT (seminoma or non-seminoma) by differential pulse voltammetry. Serum samples were obtained prior to chemotherapy, after two cycles of chemotherapy and 1 year after chemotherapy. A statistically significant difference in MT levels in patients with different stages of TGCT was observed in the serum of patients with non-seminoma obtained before chemotherapy. Although not significant, an increase in serum MT levels commensurate with the disease stage increase was also observed in patients with seminomatous TGCT. The results indicate that, in combination with the existing markers, MT could be useful for the identification of the histological type of tumor and stage of the disease before biopsy diagnosis.

Metallothionein regulates intracellular zinc signaling during CD4(+) T cell activation

BACKGROUND

The ultra-low redox potential and zinc binding properties of the intracellular pool of mammalian metallothioneins (MT) suggest a role for MT in the transduction of redox signals into intracellular zinc signals. Increased expression of MT after exposure to heavy metals, oxidative stress, or inflammatory cytokines leads to an increased intracellular redox-mobilizable zinc pool that can affect downstream zinc-sensitive signaling pathways. CD4(+) T helper cells are poised to be influenced by MT transduced zinc signaling because they produce intracellular reactive oxygen species following activation through the T cell receptor and are sensitive to small changes in intracellular [Zn(2+)].

RESULTS

MT expression and intracellular [Zn(2+)] are both increased during primary activation and expansion of naïve CD4(+) T cells into the Tr1 phenotype in vitro. When Tr1 cells from wildtype mice are compared with congenic mice lacking functional Mt1 and Mt2 genes, the expression of intracellular MT is associated with a greater increase in intracellular [Zn(2+)] immediately following exposure to reactive oxygen species or upon restimulation through the T cell receptor. The release of Zn(2+) from MT is associated with a greater increase in p38 MAPK activation following restimulation and decreased p38 MAPK activation in MT knockout Tr1 cells can be rescued by increasing intracellular [Zn(2+)]. Additionally, IL-10 secretion is increased in MT knockout Tr1 cells compared with wildtype controls and this increase is prevented when the intracellular [Zn(2+)] is increased experimentally.

CONCLUSIONS

Differences in zinc signaling associated with MT expression appear to be a result of preferential oxidation of MT and concomitant release of Zn(2+). Although zinc is released from many proteins following oxidation, release is greater when the cell contains an intracellular pool of MT. By expressing MT in response to certain environmental conditions, CD4(+) T cells are able to more efficiently release intracellular zinc and regulate signaling pathways following stimulation. The link between MT expression and increased zinc signaling following activation represents an important immunomodulatory mechanism of MT and illuminates the complex role MT plays in shaping immune responses.

A Feedback Loop between Inflammation and Zn Uptake

Objective

Zinc (Zn) has major effects on the immune system and inflammation is associated with systemic Zn deficiency. The aim of this work was to investigate how inflammation modifies Zn metabolism at the cellular level. Rheumatoid arthritis (RA) synoviocytes exposed to cytokines were used as a model of chronic inflammation. Osteoarthritis (OA) synoviocytes were used as control.

Methods

Zn levels were measured in medium and inside cells by Induced Coupled Plasma-Mass Spectrometry (ICP-MS), in the presence of minute quantities of stable spike ⁷⁰Zn isotope and the addition or not of the pro-inflammatory cytokines interleukin-17 (IL-17) and tumor necrosis factor alpha (TNF-α). Gene expression of ZIP-8 importer, ZnT1 exporter and the homeostasis regulators metallothioneins (MTs) was evaluated after pre-exposure to cytokines, with or without exogenous Zn addition at increasing concentrations. IL-6 production was used as a marker of inflammation and measured by ELISA.

Results

Exposure to IL-17 and TNF-α enhanced expression of the Zn-importer ZIP-8, regardless of the concentration of Zn in the culture medium. In contrast, the expression of the Zn-exporter ZnT1 and of the MTs was primarily dependent on Zn levels. Addition of Zn also increased the production of IL-6, thus further stimulating the inflammatory response.

Conclusion

IL-17/TNF-mediated inflammation enhanced the intracellular Zn uptake by synoviocytes, further increasing inflammation. These observations document the existence of a feedback loop between inflammation and Zn uptake. Based on these results, a mathematical model was developed to represent the cytokine-mediated Zn homeostasis alterations.

Effect of HPV on tumor expression levels of the most commonly used markers in HNSCC

Approximately 90 % of head and neck cancers are squamous cell carcinomas (HNSCC), and the overall 5-year survival rate is not higher than 50 %. There is much evidence that human papillomavirus (HPV) infection may influence the expression of commonly studied HNSCC markers. Our study was focused on the possible HPV-specificity of molecular markers that could be key players in important steps of cancerogenesis (MKI67, EGF, EGFR, BCL-2, BAX, FOS, JUN, TP53, MT1A, MT2A, VEGFA, FLT1, MMP2, MMP9, and POU5F). qRT-PCR analysis of these selected genes was performed on 74 biopsy samples of tumors from patients with histologically verified HNSCC (22 HPV-, 52 HPV+). Kaplan-Meier analysis was done to determine the relevance of these selected markers for HNSCC prognosis. In conclusion, our study confirms the impact of HPV infection on commonly studied HNSCC markers MT2A, MMP9, FLT1, VEGFA, and POU5F that were more highly expressed in HPV-negative HNSCC patients and also shows the relevance of studied markers in HPV-positive and HPV-negative HNSCC patients.

Identification of hepatocellular carcinoma-related genes with a machine learning and network analysis

Liver cancer is one of the leading causes of cancer mortality worldwide. Hepatocellular carcinoma (HCC) is the main type of liver cancer. We applied a machine learning approach with maximum-relevance-minimum-redundancy (mRMR) algorithm followed by incremental feature selection (IFS) to a set of microarray data generated from 43 tumor and 52 nontumor samples. With the machine learning approach, we identified 117 gene probes that could optimally separate tumor and nontumor samples. These genes not only include known HCC-relevant genes such as MT1X, BMI1, and CAP2, but also include cancer genes that were not found previously to be closely related to HCC, such as TACSTD2. Then, we constructed a molecular interaction network based on the protein-protein interaction (PPI) data from the STRING database and identified 187 genes on the shortest paths among the genes identified with the machine learning approach. Network analysis reveals new potential roles of ubiquitin C in the pathogenesis of HCC. Based on gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, we showed that the identified subnetwork is significantly enriched in biological processes related to cell death. These results bring new insights of understanding the process of HCC.

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.

Association of molecular biomarkers expression with biochemical recurrence in prostate cancer through tissue microarray immunostaining

The aim of the present study was to investigate the prognostic role of metallothionein-2A (MT-2A), E-cadherin, interleukin-6 (IL-6), cyclin-E, proliferating cell nuclear antigen (PCNA) and B cell lymphoma (Bcl)-2 in the biochemical recurrence of prostate cancer (PCa) using tissue microarray immunostaining. Tissue specimens from 128 PCa patients who underwent radical prostatectomy were processed and transferred onto tissue microarrays. The clinicopathological parameters of PCa patients were also recorded. Following immunohistochemical examination of MT-2A, E-cadherin, IL-6, cyclin-E, PCNA and Bcl-2 expression in PCa specimens, association analysis of biomarkers expression with the biochemical recurrence of PCa was performed. The results revealed that the overall rate of biochemical recurrence was 30.5% (39/128) and the median biochemical recurrence-free time was 19 months (range, 6–35 months). The biochemical recurrence rates in low-, intermediate- and high-risk PCa classification were 14.8 (8/54), 38.7 (24/62) and 58.3% (7/12), respectively. Survival analysis demonstrated that a decreased biochemical recurrence-free survival rate was noted in PCa cases with positive MT-2A and cyclin E expression as well as those with negative E-cadherin expression (P=0.022, 0.028 and 0.011, respectively). Subsequent multivariate Cox analysis revealed that MT-2A [hazard ratio (HR)=2.01; 95% confidence interval (CI)=1.08–3.15; P=0.005], E-cadherin (HR=1.79; 95% CI=1.08–2.21; P=0.042) and cyclin E (HR=1.92; 95% CI=1.22–2.45; P=0.020) were independent predictors of the biochemical recurrence of PCa. In conclusion, the present study provided clinical evidence that evaluation of molecular biomarkers expression may improve clinical prognostic accuracy for the biochemical recurrence of PCa. Of note, the expression of MT-2A, cyclin E and E-cadherin may serve as independent predictors for biochemical recurrence of PCa.

Prognostic significance of the tumour-adjacent tissue in head and neck cancers

Even with significant advances in operative skills and adjuvant therapies, the overall survival of patients suffering with head and neck squamous cancers (HNSCC) is unsatisfactory. Accordingly, no clinically useful prognostic biomarkers have been found yet for HNSCC. Many studies analysed the expression of potential markers in tumour tissues compared to adjacent tissues. Nevertheless, due to the sharing of the same microenvironment, adjacent tissues show molecular similarity to tumour tissues. Thus, gene expression patterns of 94 HNSCC tumorous tissues were compared with 31 adjacent tissues and with 10 tonsillectomy specimens of non-cancer individuals. The genes analysed at RNA level using quantitative RT-PCR and correlated with clinico-pathological conditions were as follows: EGF, EGFR, MKI67, BCL2, BAX, FOS, JUN, TP53, VEGF, FLT1, MMP2, MMP9, MT1A and MT2A. The elevated MT2A, BAX, EGF and JUN expression was associated with the influence of tumour cells on the rearrangement of healthy tissues, as well as a significant shift in the BAX/BCL2 ratio. Our investigation also indicated that adjacent tissues play an important role in cancerogenesis by releasing several tumour-supporting factors such as EGF. A gradual increase in the metallothionein expression, from the lowest one in tonsillectomy samples to the highest ones in tumour samples, suggests that MT expression might be tissue reaction to the presence of tumour cells. The results of this study confirmed the significance of metallothionein in tumori-genesis and gave evidences for its use as a potential HNSCC biomarker. Furthermore, this study highlighted the importance of histologically normal tumour-adjacent tissue in prediction of HNSCC progress.

Metallothionein immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour

Background

To compare the metallothionein (MT) immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour (KOT), to correlate MT with cellular proliferation, and to evaluate the influence of inflammation in MT.

Material and Methods

Fourteen cases of KOT were submitted to immunohistochemistry for MT and Ki-67 analysis. The lesions were grouped according to their grade of inflammation, and statistical analysis was performed.

Results

MT was higher in non-syndromic KOT than in syndromic KOT (p<0.05). No statistical difference in Ki-67 could be identified; however, an inverse correlation was observed between MT and Ki-67 in both lesions. When analysing inflammation, non-syndromic KOT showed no differences in either MT or Ki-67.

Conclusions

The MT immunophenotype of syndromic KOT was different from non-syndromic KOT. MT might not be involved in the proliferation control of both KOT. MT and Ki-67 immunoexpressions proved to be unaffected by inflammation in non-syndromic KOT.

Key words: Odontogenic tumours, basal cell nevus syndrome, metallothionein, Ki-67 Antigen, immunohistoche-mistry.

Metallothionein 2A core promoter region genetic polymorphism and its impact on the risk, tumor behavior, and recurrences of sinonasal inverted papilloma (Schneiderian papilloma)

Inverted papillomas are a unique group of locally aggressive benign epithelial neoplasms in the nasal cavity and paranasal sinuses arising from the Schneiderian mucosa. Metallothioneins are sulfhydryl-rich heavy metal-binding proteins required for metal toxicity protection and regulation of biological mechanisms including proliferation and invasion. The goal of this study was to identify three SNPs at loci −5 A/G (rs28366003) and −209 A/G (rs1610216) in the core promoter region and at locus +838 C/G (rs10636) in 3′UTR region of the MT2A gene with IP risk and with tumor invasiveness according to Krouse staging. Genotyping was performed using the PCR restriction fragment length polymorphism technique in 130 genetically unrelated IP individuals, and 418 randomly selected healthy volunteers. The presence of the rs28366003 SNP was significantly related to the risk of IP within the present population-based case-control study. Compared to homozygous common allele carriers, heterozygosity and homozygosity for the G variant had a significantly increased risk of IP (adjusted odds ratio [OR] = 7.71, 95 % confidence interval [CI]: 4.01–14.91, p_dominant < 0.001). Moreover, risk allele carriers demonstrated higher Krouse stage (pT1 vs. pT2-4) (OR = 19.32; 95 % CI, 2.30–173.53; p < 0.0001), diffuse tumor growth (OR = 4.58; 95 % CI, 1.70–12.11; p = 0.0008), bone destruction (OR = 4.13; 95 % CI, 1.50–11.60; p = 0.003), and higher incidence of tumor recurrences (OR = 5.11; 95 % CI, 1.68–15.20; p = 0.001). The findings suggest that MT2A gene variation rs28366003 may be implicated in the etiology of sinonasal inverted papilloma in a Polish population.

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.

Molecular response of 4T1-induced mouse mammary tumours and healthy tissues to zinc treatment

Breast cancer patients negative for the nuclear oestrogen receptor α have a particularly poor prognosis. Therefore, the 4T1 cell line (considered as a triple-negative model) was chosen to induce malignancy in mice. The aim of the present study was to assess if zinc ions, provided in excess, may significantly modify the process of mammary oncogenesis. Zn(II) ions were chosen because of their documented antitumour effects. Zn(II) is also known to induce the expression of metallothioneins (MT) and glutathion (GSH). A total dose of zinc sulphate per one gram of mouse weight used in the experiment was 0.15 mg. We studied the expression of MT1, MT2, TP53 and MTF-1 genes and also examined the effect of the tumour on antioxidant capacity. Tumour-free mice had significantly higher expression levels of the studied genes (p<0.003). Significant differences were also revealed in the gene expression between the tissues (p<0.001). The highest expression levels were observed in the liver. As compared to brain, lung and liver, significantly lower concentrations of MT protein were found in the primary tumour; an inverse trend was observed in the concentration of Zinc(II). In non-tumour mice, the amount of hepatic hydrosulphuryl groups significantly increased by the exposure to Zn(II), but the animals with tumour induction showed no similar trend. The primary tumour size of zinc-treated animals was 20% smaller (p=0.002); however, no significant effect on metastasis progression due to the zinc treatment was discovered. In conclusion, Zn(II) itself may mute the growth of primary breast tumours especially at their early stages.

Serum metallothionein in patients with testicular cancer

PURPOSE

Metallothioneins (MTs) have been disclosed as a useful diagnostic factor for tumour progression and drug resistance in a variety of malignancies. Increased levels of MT in blood serum have been found in patients with several types of cancer, but there is no available information on serum MT levels in patients with testicular germ cell tumour (TGCT). The aim of the study was to determine MT levels in serum of patients with TGCT and to evaluate the portion of platinum (Pt) that binds to MT after cisplatin administration since MTs could be involved in drug resistance.

METHODS

Concentration of total MT was determined in serum of 25 men with newly diagnosed TGCT by differential pulse voltammetry. The fractionation of serum was carried out by size exclusion high-performance liquid chromatography (SE-HPLC), while concentration of Pt in collected fractions was determined by inductively coupled plasma mass spectrometry.

RESULTS

Concentration of serum MT was significantly higher in TGCT patients than in healthy volunteers. The results of SE-HPLC analysis showed that only a small amount of Pt was bound to proteins in the area of MT elution.

CONCLUSIONS

Significant increase in MT levels in individuals with TGCT indicates certain health problem and, in combination with other commonly used diagnostic tools, could improve early diagnosis.

Molecular basis of carcinogenicity of tungsten alloy particles

The tungsten alloy of 91% tungsten, 6% nickel and 3% cobalt (WNC 91-6-3) induces rhabdomyosarcoma when implanted into a rat thigh muscle. To investigate whether this effect is species-specific human HSkMc primary muscle cells were exposed to WNC 91-6-3 particles and responses were compared with those from a rat skeletal muscle cell line (L6-C11). Toxicity was assessed by the adenylate kinase assay and microscopy, DNA damage by the Comet assay. Caspase 3 enzyme activity was measured and oligonucleotide microarrays were used for transcriptional profiling. WNC 91-6-3 particles caused toxicity in cells adjacent to the particles and also increased DNA strand breaks. Inhibition of caspase 3 by WNC 91-6-3 occurred in rat but not in human cells. In both rat and human cells, the transcriptional response to WNC 91-6-3 showed repression of transcripts encoding muscle-specific proteins with induction of glycolysis, hypoxia, stress responses and transcripts associated with DNA damage and cell death. In human cells, genes encoding metallothioneins were also induced, together with genes related to angiogenesis, dysregulation of apoptosis and proliferation consistent with pre-neoplastic changes. An alloy containing iron, WNF 97-2-1, which is non-carcinogenic in vivo in rats, did not show these transcriptional changes in vitro in either species while the corresponding cobalt-containing alloy, WNC 97-2-1 elicited similar responses to WNC 91-6-3. Tungsten alloys containing both nickel and cobalt therefore have the potential to be carcinogenic in man and in vitro assays coupled with transcriptomics can be used to identify alloys, which may lead to tumour formation, by dysregulation of biochemical processes.

Zinc and its role in immunity and inflammation

Zinc (Zn) nutritional importance has been known for a long time, but in the last decades its importance in immune modulation has arisen. This review aims at describing the mechanisms involved in the regulation of Zn homeostasis and their effects on the immune response focusing on those which are implicated in the physiopathology of rheumatoid arthritis. Zn functions as a modulator of the immune response through its availability, which is tightly regulated by several transporters and regulators. When this mechanism is disturbed, Zn availability is reduced, altering survival, proliferation and differentiation of the cells of different organs and systems and, in particular, cells of the immune system. Zn deficiency affects cells involved in both innate and adaptive immunity at the survival, proliferation and maturation levels. These cells include monocytes, polymorphonuclear-, natural killer-, T-, and B-cells. T cell functions and the balance between the different T helper cell subsets are particularly susceptible to changes in Zn status. While acute Zn deficiency causes a decrease in innate and adaptive immunity, chronic deficiency increases inflammation. During chronic deficiency, the production of pro-inflammatory cytokines increases, influencing the outcome of a large number of inflammatory diseases, including rheumatoid arthritis.

Biomarkers to assess the efficiency of treatment with platinum-based drugs: what can metallomics add?

Since the approval of cisplatin as an antineoplastic drug, the medical and the scientific communities have been concerned about the side effects of platinum-based drugs, and this has been the dose-limiting factor that leads to reduced treatment efficiency. Another important issue is the intrinsic or acquired resistance of some patients to treatment. Identifying proper biomarkers is crucial in evaluating the efficiency of a treatment, assisting physicians in determining, at early stages, whether or not the patient presents resistance to the drug, minimizing severe side effects, and allowing them to redirect the established course of chemotherapy. A great effort is being made to identify biomarkers that can be used to predict the outcome of the treatment of cancer patients with platinum-based drugs. In this context, the metallomic approach has not yet been used to its full potential. Since the basis of these drugs is platinum, the monitoring of biomarkers containing this metal should be the natural approach to evaluate treatment progress. This review intends to show where the research in this field stands and points out some gaps that can be filled by metallomics.