Metallothionein MT1M is a tumor suppressor of human hepatocellular carcinomas

Microproteins encoded by noncanonical ORFs are a major source of tumor-specific antigens in a liver cancer patient meta-cohort

The expression of tumor-specific antigens during cancer progression can trigger an immune response against the tumor. Here, we investigate if microproteins encoded by noncanonical open reading frames (ncORFs) are a relevant source of tumor-specific antigens. We analyze RNA sequencing data from 117 hepatocellular carcinoma (HCC) tumors and matched healthy tissue together with ribosome profiling and immunopeptidomics data. Combining human leukocyte antigen-epitope binding predictions and experimental validation experiments, we conclude that around 40% of the tumor-specific antigens in HCC are likely to be derived from ncORFs, including two peptides that can trigger an immune response in humanized mice. We identify a subset of 33 tumor-specific long noncoding RNAs expressing novel cancer antigens shared by more than 10% of the HCC samples analyzed, which, when combined, cover a large proportion of the patients. The results of the study open avenues for extending the range of anticancer vaccines.

ProstaMine: a bioinformatics tool for identifying subtype-specific co-alterations associated with aggressiveness in prostate cancer

Background

Prostate cancer is a leading cause of cancer-related deaths among men, marked by heterogeneous clinical and molecular characteristics. The complexity of the molecular landscape necessitates tools for identifying multi-gene co-alteration patterns that are associated with aggressive disease. The identification of such gene sets will allow for deeper characterization of the processes underlying prostate cancer progression and potentially lead to novel strategies for treatment.

Methods

We developed ProstaMine to systematically identify co-alterations associated with aggressiveness in prostate cancer molecular subtypes defined by high-fidelity alterations in primary prostate cancer. ProstaMine integrates genomic, transcriptomic, and clinical data from five primary and one metastatic prostate cancer cohorts to prioritize co-alterations enriched in metastatic disease and associated with disease progression.

Results

Integrated analysis of primary tumors defined a set of 17 prostate cancer alterations associated with aggressive characteristics. We applied ProstaMine to NKX3-1-loss and RB1-loss tumors and identified subtype-specific co-alterations associated with metastasis and biochemical relapse in these molecular subtypes. In NKX3-1-loss prostate cancer, ProstaMine identified novel subtype-specific co-alterations known to regulate prostate cancer signaling pathways including MAPK, NF-kB, p53, PI3K, and Sonic hedgehog. In RB1-loss prostate cancer, ProstaMine identified novel subtype-specific co-alterations involved in p53, STAT6, and MHC class I antigen presentation. Co-alterations impacting autophagy were noted in both molecular subtypes.

Conclusion

ProstaMine is a method to systematically identify novel subtype-specific co-alterations associated with aggressive characteristics in prostate cancer. The results from ProstaMine provide insights into potential subtype-specific mechanisms of prostate cancer progression which can be formed into testable experimental hypotheses. ProstaMine is publicly available at: https://bioinformatics.cuanschutz.edu/prostamine.

Metallothionein-3 is a multifunctional driver that modulates the development of sorafenib-resistant phenotype in hepatocellular carcinoma cells

BACKGROUND & AIMS

Metallothionein-3 (hMT3) is a structurally unique member of the metallothioneins family of low-mass cysteine-rich proteins. hMT3 has poorly characterized functions, and its importance for hepatocellular carcinoma (HCC) cells has not yet been elucidated. Therefore, we investigated the molecular mechanisms driven by hMT3 with a special emphasis on susceptibility to sorafenib.

METHODS

Intrinsically sorafenib-resistant (BCLC-3) and sensitive (Huh7) cells with or without up-regulated hMT3 were examined using cDNA microarray and methods aimed at mitochondrial flux, oxidative status, cell death, and cell cycle. In addition, in ovo/ex ovo chick chorioallantoic membrane (CAM) assays were conducted to determine a role of hMT3 in resistance to sorafenib and associated cancer hallmarks, such as angiogenesis and metastastic spread. Molecular aspects of hMT3-mediated induction of sorafenib-resistant phenotype were delineated using mass-spectrometry-based proteomics.

RESULTS

The phenotype of sensitive HCC cells can be remodeled into sorafenib-resistant one via up-regulation of hMT3. hMT3 has a profound effect on mitochondrial respiration, glycolysis, and redox homeostasis. Proteomic analyses revealed a number of hMT3-affected biological pathways, including exocytosis, glycolysis, apoptosis, angiogenesis, and cellular stress, which drive resistance to sorafenib.

CONCLUSIONS

hMT3 acts as a multifunctional driver capable of inducing sorafenib-resistant phenotype of HCC cells. Our data suggest that hMT3 and related pathways could serve as possible druggable targets to improve therapeutic outcomes in patients with sorafenib-resistant HCC.

MT1M regulates gastric cancer progression and stemness by modulating the Hedgehog pathway protein GLI1

Gastric cancer (GC) is a highly prevalent and aggressive malignancy with a poor prognosis. Recent evidence suggested that metallothionein 1 M (MT1M) may play a critical role in cancer development, progression, and drug resistance; however, its role in GC remains largely unknown. In this study, we investigated the expression and function of MT1M in GC both in vitro and in vivo. We found that MT1M expression was significantly downregulated in GC tissues and cell lines. Decreased expression of MT1M was associated with worse clinical prognosis, particularly in patients treated with 5-fluorouracil. Low expression of MT1M was indicative of poor overall survival (OS, HR 0.56 [95% CI 0.37-0.84], P < 0.005), first progression survival (FP, HR 0.54 [95% CI 0.36-0.79], P < 0.005), and post-progression survival (PPS, HR 0.65 [95% CI 0.45-0.94], P < 0.05). We also demonstrated that overexpression of MT1M inhibited cell proliferation and induced apoptosis in GC cells and in tumor xenografts, and it improved chemosensitivity to 5-fluorouracil. Furthermore, we found that MT1M overexpression could inhibit stem cell characteristics by targeting GLI1 and affecting GLI1 ubiquitination. Collectively, these findings indicated that MT1M may act as a tumor suppressor in GC and could serve as a potential therapeutic target to attenuate stemness and chemotherapy resistance of GC.

Epigenetic reactivation of tumor suppressor genes with CRISPRa technologies as precision therapy for hepatocellular carcinoma

BACKGROUND

Epigenetic silencing of tumor suppressor genes (TSGs) is a key feature of oncogenesis in hepatocellular carcinoma (HCC). Liver-targeted delivery of CRISPR-activation (CRISPRa) systems makes it possible to exploit chromatin plasticity, by reprogramming transcriptional dysregulation.

RESULTS

Using The Cancer Genome Atlas HCC data, we identify 12 putative TSGs with negative associations between promoter DNA methylation and transcript abundance, with limited genetic alterations. All HCC samples harbor at least one silenced TSG, suggesting that combining a specific panel of genomic targets could maximize efficacy, and potentially improve outcomes as a personalized treatment strategy for HCC patients. Unlike epigenetic modifying drugs lacking locus selectivity, CRISPRa systems enable potent and precise reactivation of at least 4 TSGs tailored to representative HCC lines. Concerted reactivation of HHIP, MT1M, PZP, and TTC36 in Hep3B cells inhibits multiple facets of HCC pathogenesis, such as cell viability, proliferation, and migration.

CONCLUSIONS

By combining multiple effector domains, we demonstrate the utility of a CRISPRa toolbox of epigenetic effectors and gRNAs for patient-specific treatment of aggressive HCC.

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.

Atorvastatin favorably modulates a clinical hepatocellular carcinoma risk gene signature

Lipophilic but not hydrophilic statins have been shown to be associated with reduced risk for hepatocellular carcinoma (HCC) in patients with chronic viral hepatitis. We investigated differential actions of lipophilic and hydrophilic statins and their ability to modulate a clinical prognostic liver signature (PLS) predicting HCC risk in patients with liver disease. Hepatitis C virus (HCV)–infected Huh7.5.1 cells, recently developed as a model to screen HCC chemopreventive agents, were treated with lipophilic statins (atorvastatin and simvastatin) and hydrophilic statins (rosuvastatin and pravastatin), and then analyzed by RNA sequencing and PLS. Lipophilic statins, particularly atorvastatin, more significantly suppressed the HCV‐induced high‐risk pattern of PLS and genes in YAP and AKT pathway implicated in fibrogenesis and carcinogenesis, compared with the hydrophilic statins. While atorvastatin inhibited YAP activation through the mevalonate pathway, the distinctive AKT inhibition of atorvastatin was mediated by stabilizing truncated retinoid X receptor alpha, which has been known to enhance AKT activation, representing a target for HCC chemoprevention. In addition, atorvastatin modulated the high‐risk PLS in an in vitro model of nonalcoholic fatty liver disease (NAFLD). Conclusion: Atorvastatin distinctively inhibits YAP and AKT activation, which are biologically implicated in HCC development, and attenuates a high‐risk PLS in an in vitro model of HCV infection and NAFLD. These findings suggest that atorvastatin is the most potent statin to reduce HCC risk in patients with viral and metabolic liver diseases.

Transcriptomics-Based Investigation of Molecular Mechanisms Underlying Apoptosis Induced by ZnO Nanoparticles in Human Diffuse Large B-Cell Lymphoma

Introduction

Zinc oxide nanoparticles (ZnO NPs) show anti-cancer activity. Diffuse Large B-cell Lymphoma (DLBCL) is a type of B-cell malignancies with unsatisfying treatment outcomes. This study was set to assess the potential of ZnO NPs to selectively induce apoptosis in human DLBCL cells (OCI-LY3), and to describe possible molecular mechanisms of action.

Methods

The impact of ZnO NPs on DLBCL cells and normal peripheral blood mononuclear cells (PBMCs) was studied using cytotoxicity assay and flow-cytometry. Transcriptomics analysis was conducted to identify ZnO NPs-dependent changes in the transcriptomic profiles of DLBCL cells.

Results

ZnO NPs selectively induced apoptosis in DLBCL cells, and caused changes in their transcriptomes. Deferential gene expression (DGE) with fold change (FC) ≥3 and p ≤ 0.008 with corrected p ≤ 0.05 was identified for 528 genes; 125 genes were over-expressed and 403 genes were under-expressed in ZnO NPs-treated DLBCL cells. The over-expressed genes involved in biological processes and pathways like stress response to metal ion, cellular response to zinc ion, metallothioneins bind metals, oxidative stress, and negative regulation of growth. In contrast, the under-expressed genes were implicated in DNA packaging complex, signaling by NOTCH, negative regulation of gene expression by epigenetic, signaling by WNT, M phase of cell cycle, and telomere maintenance. Setting the FC to ≥1.5 with p ≤ 0.05 and corrected p ≤ 0.1 showed ZnO NPs to induce over-expression of anti-oxidant genes and under-expression of oncogenes; target B-cell receptor (BCR) signaling pathway and NF-κB pathway; and promote apoptosis by intrinsic and extrinsic pathways.

Discussion

Overall, ZnO NPs selectively induced apoptosis in DLBCL cells, and possible molecular mechanisms of action were described.

Integration analysis identifies the role of metallothionein in the progression from hepatic steatosis to steatohepatitis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), a metabolic disorder that develops from non-alcoholic fatty liver (NAFL) to non-alcoholic steatohepatitis (NASH), has become an epidemic of chronic liver dysfunction worldwide. However, mechanisms that govern the transition from NAFL to NASH have not been fully elucidated.

METHODS

Gene expression profile data of NAFLD liver tissues were obtained from Gene Expression Omnibus (GEO), including three microarray datasets with 60 NAFL and 44 NASH patients. Integrative differentially expressed genes (DEGs) between NAFL and NASH patients were identified using robust rank aggregation (RRA) analysis. Hub genes were identified combined with gene ontology functional annotation and protein-protein interaction network construction and validated using a sequencing dataset. Huh-7 cells with palmitate-induced lipid overload and NAFLD-diet mouse model of different stages were used to verify our findings.

RESULTS

RRA analysis determined 70 robust DEGs between NAFL and NASH. The most robustly upregulated genes were SPP1, AKR1B10, CHST9, and ANXA2, while the most robustly downregulated DEGs were SNORD94, SCARNA10, SNORA20, and MT1M. Cellular response to zinc ion (GO: 0071294) ranked first in GO analysis of downregulated genes, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment showed that mineral absorption (hsa04978) was significantly enriched. The involvement of the metallothionein pathway was further validated by the decrease of Mt1 expression during NAFL to NASH progression in NAFLD mice and the protection from lipotoxicity in liver cells by overexpressing MT1M.

CONCLUSIONS

Our integrated analysis identified novel gene signatures and provided comprehensive molecular mechanisms underlying the transition from NAFL to NASH. Metallothionein might be a potential intervention target for NAFLD progression.

Metallothionein 1: A New Spotlight on Inflammatory Diseases

MT1 has been demonstrated to be an essential stress protein in maintaining physiological balance and regulating immune homeostasis. While the immunological involvement of MT1 in central nervous system disorders and cancer has been extensively investigated, mounting evidence suggests that MT1 has a broader role in inflammatory diseases and can shape innate and adaptive immunity. In this review, we will first summarize the biological features of MT1 and the regulators that influence MT1 expression, emphasizing metal, inflammation, and immunosuppressive factors. We will then focus on the immunoregulatory function of MT1 on diverse immune cells and the signaling pathways regulated by MT1. Finally, we will discuss recent advances in our knowledge of the biological role of MT1 in several inflammatory diseases to develop novel therapeutic strategies.

MTF1 Is Essential for the Expression of MT1B, MT1F, MT1G, and MT1H Induced by PHMG, but Not CMIT, in the Human Pulmonary Alveolar Epithelial Cells

The inhalation of humidifier disinfectants (HDs) is linked to HD-associated lung injury (HDLI). Polyhexamethylene guanidine (PHMG) is significantly involved in HDLI, but the correlation between chloromethylisothiazolinone (CMIT) and HDLI remains ambiguous. Additionally, the differences in the molecular responses to PHMG and CMIT are poorly understood. In this study, RNA sequencing (RNA-seq) data showed that the expression levels of metallothionein-1 (MT1) isoforms, including MT1B, MT1E, MT1F, MT1G, MT1H, MT1M, and MT1X, were increased in human pulmonary alveolar epithelial cells (HPAEpiCs) that were treated with PHMG but not in those treated with CMIT. Moreover, upregulation of MT1B, MT1F, MT1G, and MT1H was observed only in PHMG-treated HPAEpiCs. The protein expression level of metal regulatory transcription factor 1 (MTF1), which binds to the promoters of MT1 isoforms, was increased in PHMG-treated HPAEpiCs but not in CMIT-treated HPAEpiCs. However, the expression of early growth response 1 (EGR1) and nuclear receptor superfamily 3, group C, member 1 (NR3C1), other transcriptional regulators involved in MT1 isomers, were increased regardless of treatment with PHMG or CMIT. These results suggest that MTF1 is an essential transcription factor for the induction of MT1B, MT1F, MT1G, and MT1H by PHMG but not by CMIT.

Identification of Key Functional Modules and Immunomodulatory Regulators of Hepatocellular Carcinoma

Despite the advances in the treatment of hepatocellular carcinoma (HCC), the prognosis of HCC patients remains unsatisfactory due to postsurgical recurrence and treatment resistance. Therefore, it is important to reveal the mechanisms underlying HCC and identify potential therapeutic targets against HCC, which could facilitate the development of novel therapies. Based on 12 HCC samples and 12 paired paracancerous normal tissues, we identified differentially expressed mRNAs and lncRNAs using the "limma" package in R software. Moreover, we used the weighted gene coexpression network analysis (WGCNA) to analyze the expression data and screened hub genes. Furthermore, we performed pathway enrichment analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. In addition, the relative abundance of a given gene set was estimated by single-sample Gene Set Enrichment Analysis. We identified 687 differentially expressed mRNAs and 260 differentially expressed lncRNAs. A total of 6 modules were revealed by WGCNA, and MT1M and MT1E genes from the red module were identified as hub genes. Moreover, pathway analysis revealed the top 10 enriched KEGG pathways of upregulated or downregulated genes. Additionally, we also found that CD58 might act as an immune checkpoint gene in HCC via PD1/CTLA4 pathways and regulate the levels of tumor-infiltrating immune cells in HCC tissues, which might be an immunotherapeutic target in HCC. Our research identified key functional modules and immunomodulatory regulators for HCC, which might offer novel diagnostic biomarkers and/or therapeutic targets for cancer immunotherapy.

Metallothionein MT1M Suppresses Carcinogenesis of Esophageal Carcinoma Cells through Inhibition of the Epithelial-Mesenchymal Transition and the SOD1/PI3K Axis

Metallothionein (MT1M) belongs to a family of cysteine-rich cytosolic protein and has been reported to be a tumor suppressor gene in multiple cancers. However, its role in esophageal carcinoma carcinogenesis remains unclear. In this study, MT1M expression was correlated with tumor type, stage, drinking and smoking history, as well as patient survival. We also studied the regulation and biological function of MT1M in esophageal squamous cell carcinoma (ESCC). We have found that MT1M is significantly downregulated in ESCC tissues compared with adjacent non-cancer tissues. Furthermore, restoration of expression by treatment with the demethylation agent A + T showed that MT1M downregulation might be closely related to hypermethylation in its promoter region. Over-expression of MT1M in ESCC cells significantly altered cell morphology, induced apoptosis, and reduced colony formation, cell viability, migration and epithelial-mesenchymal transition. Moreover, based on reactive oxygen species (ROS) levels, a superoxide dismutase 1 (SOD1) activity assay and protein analysis, we verified that the tumor-suppressive function of MT1M was at least partially caused by its upregulation of ROS levels, downregulation of SOD1 activity and phosphorylation of the SOD1 downstream pathway PI3K/AKT. In conclusion, our results demonstrated that MT1M was a novel tumor-suppressor in ESCC and may be disrupted by promoter CpG methylation during esophageal carcinogenesis.

Integrative Analysis of Metallothioneins Identifies MT1H as Candidate Prognostic Biomarker in Hepatocellular Carcinoma

Background: Metallothioneins (MTs) play crucial roles in the modulation of zinc/copper homeostasis, regulation of neoplastic growth and proliferation, and protection against apoptosis. The present study attempted to visualize the prognostic landscape of MT functional isoforms and identify potential prognostic biomarkers in hepatocellular carcinoma (HCC). Methods: The transcriptional expression, comprehensive prognostic performances, and gene-gene interaction network of MT isoforms in HCC were evaluated via Oncomine, GEPIA, Kaplan-Meier plotter, and GeneMANIA databases. Characterized by good prognostic value in three external cohorts, MT1H was specifically selected as a potential prognostic biomarker in HCC with various clinicopathological features. Functional and pathway enrichment analyses of MT1H status were performed using cBioPortal, the Database for Annotation, Visualization, and Integrated Discovery (DAVID), and ssGSVA method. Results: MT1E/1F/1G/1H/1M/1X/2A was greatly downregulated in HCC. Prognostic analyses elucidated the essential correlations between MT1A/1B/1H/1X/2A/4 attenuation and poor overall survival, between MT1B/1H/4 downregulation and worse relapse-free survival, and between MT1A/1B/1E/1H/1M/2A/4 downregulation and diminished progression-free survival in HCC. Taken together, these results indicated the powerful prognostic value of MT1H among MTs in HCC. In-depth analyses suggested that MT1H may be more applicable to alcohol-derived HCC and involved in the downregulation of the inflammatory pathway, Jak-STAT pathway, TNF pathway, and Wnt signaling pathway. Conclusion: MT-specific isoforms displayed aberrant expression and varying prognostic value in HCC. MT1H repression in HCC was multi-dimensionally detrimental to patient outcomes. Therefore, MT1H was possibly associated with carcinogenesis and exploited as a novel prognostic biomarker and candidate therapeutic target for HCC.

Proprotein convertases blockage up-regulates specifically metallothioneins coding genes in human colon cancer stem cells

Despite continuous exertion made, colon cancer still represents a major health problem and its incidence continues being high worldwide. There is growing evidence in support of the cancer stem cells (CSCs) being central in the initiation of this cancer, and CSCs have been the focus of various studies for the identification of new ways of treatment. Lately, the proprotein convertases (PCs) were reported to regulate the maturation and expression of various molecules involved in the malignant phenotype of colon cancer cells, however, the identity of the molecules regulated by these serine proteases in CSCs is unknown. In this study, we used the general PCs inhibitor, the Decanoyl-RVKR-chloromethylketone (Decanoyl-RVKR-CMK) that inhibits all the PCs found in the secretory pathway, and analyzed its effect on CSCs using RNA-seq analysis. Remarkably, from the only 9 up-regulated genes in the human SW620-derived sphere-forming cells, we identified 7 of the 11 human metallothioneins, all of them localized on chromosome 16, and zinc related proteins as downstream effectors of the PCs. The importance of these molecules in the regulation of cell proliferation, differentiation and chemoresistance, and their reported potential tumor suppressor role and loss in colon cancer patients associated with worse prognosis, suggests that targeting PCs in the control of the malignant phenotype of CSCs is a new potential therapeutic strategy in colon cancer.

Transcriptomics-Based Characterization of the Toxicity of ZnO Nanoparticles Against Chronic Myeloid Leukemia Cells

INTRODUCTION

Zinc oxide nanoparticles (ZnO NPs) have recently attracted attention as potential anti-cancer agents. To the best of our knowledge, the toxicity of ZnO NPs against human chronic myeloid leukemia cells (K562 cell line) has not been studied using transcriptomics approach.

OBJECTIVE

The goals of this study were to evaluate the capability of ZnO NPs to induce apoptosis in human chronic myeloid leukemia cells (K562 cells) and to investigate the putative mechanisms of action.

METHODS

We used viability assay and flowcytometry coupled with Annexin V-FITC and propidium iodide to investigate the toxicity of ZnO NPs on K562 cells and normal peripheral blood mononuclear cells. Next we utilized a DNA microarray-based transcriptomics approach to characterize the ZnO NPs-induced changes in the transcriptome of K562 cells.

RESULTS

ZnO NPs exerted a selective toxicity (mainly by apoptosis) on the leukemic cells (p≤0.005) and altered their transcriptome; 429 differentially expressed genes (DEGs) with fold change (FC)≥4 and p≤0.008 with corrected p≤0.05 were identified in K562 cells post treatment with ZnO NPs. The over-expressed genes were implicated in "response to zinc", "response to toxic substance" and "negative regulation of growth" (corrected p≤0.05). In contrast, the repressed genes positively regulated "cell proliferation", "cell migration", "cell adhesion", "receptor signaling pathway via JAK-STAT" and "phosphatidylinositol 3-kinase signaling" (corrected p≤0.05). Lowering the FC to ≥1.5 with p≤0.05 and corrected p≤0.1 showed that ZnO NPs over-expressed the anti-oxidant defense system, drove K562 cells to undergo mitochondrial-dependent apoptosis, and targeted NF-κB pathway.

CONCLUSION

Taken together, our findings support the earlier studies that reported anti-cancer activity of ZnO NPs and revealed possible molecular mechanisms employed by ZnO NPs to induce apoptosis in K562 cells.

Engineered metal nanoparticles in the marine environment: A review of the effects on marine fauna

There is an increasing awareness of how damaging pollutants in the marine environment can be, however information on the effects of metal engineered nanoparticles (ENPs) on marine biota is still insufficient, despite an exponential rising in related publications in recent years. In order to provide an integrated insight on the present state of the art on metal ENP-related ecotoxicology studies on marine fauna, this review aimed to: (i) highlight the means of toxicity of metal ENPs in the marine environment, (ii) identify the principal biotic and abiotic factors that may alter metal ENP toxicity, and (iii) analyse and categorize results of these studies, including accumulation, molecular and histological biomarkers, genotoxicity and behavioural changes. Data retrieved from Scopus yielded 134 studies that met pre-established criteria. Most often, the target ENPs were titanium, zinc, copper or silver, and most studies (61.2%) focused on the phylum Mollusca. The degree of toxicity of metal ENPs was often dependent on the concentrations tested, length of exposure and the type of tissue sampled. Effects from simple tissue accumulation to DNA damage or behavioural alterations were identified, even when concentrations below environmentally available levels were used. It is proposed that other phyla besides the traditional Mollusca (and within it Bivalvia) should be used more often in this kind of studies, that exact pathways of toxicity be further explored, and lastly that co-stressors be used in order to best mimic conditions observed in nature. In this review, the current knowledge on engineered metal nanoparticles and their effects on marine fauna was summarized, highlighting present knowledge gaps. Guidelines for future studies focusing on under-developed subjects in ENP toxicology are also briefly provided.

An Integrative Synthetic Biology Approach to Interrogating Cellular Ubiquitin and Ufm Signaling

Global identification of substrates for PTMs (post-translational modifications) represents a critical but yet dauntingly challenging task in understanding biology and disease pathology. Here we presented a synthetic biology approach, namely ‘YESS’, which coupled Y2H (yeast two hybrid) interactome screening with PTMs reactions reconstituted in bacteria for substrates identification and validation, followed by the functional validation in mammalian cells. Specifically, the sequence-independent Gateway^® cloning technique was adopted to afford simultaneous transfer of multiple hit ORFs (open reading frames) between the YESS sub-systems. In proof-of-evidence applications of YESS, novel substrates were identified for UBE3A and UFL1, the E3 ligases for ubiquitination and ufmylation, respectively. Therefore, the YESS approach could serve as a potentially powerful tool to study cellular signaling mediated by different PTMs.

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.

Metallothionein Expression and its Influence on the In Vitro Biological Behavior of Mucoepidermoid Carcinoma

Mucoepidermoid carcinoma (MEC) is the most common tumor in the salivary glands, often presenting with recurrence and metastasis due to its high invasive capacity. Metallothionein (MT), a zinc storage protein that supplies this element for protease activity, is probably related to mucoepidermoid carcinoma behavior. This prompted us to characterize a cell line derived from mucoepidermoid carcinoma and to correlate metallothionein expression with transforming growth factor-α (TGF-α), tumor necrosis factor-α (TNF-α) and matrix metalloproteinases (MMPs). Transcriptomic analysis and cytogenetic assays were performed to detect the expression of genes of interest and cellular chromosomal alterations, respectively. MEC cells with a depleted metallothionein 2A (MT2A) gene were subjected to Western blot to correlate metallothionein expression with growth factors and MMPs. Additionally, cells with depleted MT were subjected to migration and invasion assays. The transcriptomic study revealed reads mapped to cytokeratins 19 and AE1/AE3, α-smooth muscle actin, vimentin, and fibronectin. Cytogenetic evaluation demonstrated structural and numerical alterations, including the translocation t(11;19)(q21;p13), characteristic of MEC. Metallothionein depletion was correlated with the decreased expression of TGF-α and MMP-9, while TNF-α protein levels were augmented. Migration and invasion activity were diminished after metallothionein silencing. Our findings suggest an important role of MT in MEC invasion, through the regulation of proteins involved in this process.

MT1G serves as a tumor suppressor in hepatocellular carcinoma by interacting with p53

Poor prognosis of hepatocellular carcinoma (HCC) patients is frequently associated with rapid tumor growth, recurrence and drug resistance. MT1G is a low-molecular weight protein with high affinity for zinc ions. In the present study, we investigated the expression of MT1G, analyzed clinical significance of MT1G, and we observed the effects of MT1G overexpression on proliferation and apoptosis of HCC cell lines in vitro and in vivo. Our results revealed that MT1G was significantly downregulated in tumor tissues, and could inhibit the proliferation as well as enhance the apoptosis of HCC cells. The mechanism study suggested that MT1G increased the stability of p53 by inhibiting the expression of its ubiquitination factor, MDM2. Furthermore, MT1G also could enhance the transcriptional activity of p53 through direct interacting with p53 and providing appropriate zinc ions to p53. The modulation of MT1G on p53 resulted in upregulation of p21 and Bax, which leads cell cycle arrest and apoptosis, respectively. Our in vivo assay further confirmed that MT1G could suppress HCC tumor growth in nude mice. Overall, this is the first report on the interaction between MT1G and p53, and adequately uncover a new HCC suppressor which might have therapeutic values by diminishing the aggressiveness of HCC cells.

Comprehensive investigation of key biomarkers and pathways in hepatitis B virus-related hepatocellular carcinoma

Objective: Our study is aim to explore potential key biomarkers and pathways in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) using genome-wide expression profile dataset and methods.

Methods: Dataset from the GSE14520 is used as the training cohort and The Cancer Genome Atlas dataset as the validation cohort. Differentially expressed genes (DEGs) screening were performed by the limma package. Gene set enrichment analysis (GSEA), weighted gene co-expression network analysis (WGCNA), gene ontology, the Kyoto Encyclopedia of Genes and Genomes, and risk score model were used for pathway and genes identification.

Results: GSEA revealed that several pathways and biological processes are associated with hepatocarcinogenesis, such as the cell cycle, DNA repair, and p53 pathway. A total of 160 DEGs were identified. The enriched functions and pathways of the DEGs included toxic substance decomposition and metabolism processes, and the P450 and p53 pathways. Eleven of the DEGs were identified as hub DEGs in the WGCNA. In survival analysis of hub DEGs, high expression of PRC1 and TOP2A were significantly associated with poor clinical outcome of HBV-related HCC, and shown a good performance in HBV-related HCC diagnosis. The prognostic signature consisting of PRC1 and TOP2A also doing well in the prediction of HBV-related HCC prognosis. The diagnostic and prognostic values of PRC1 and TOP2A was confirmed in TCGA HCC patients.

Conclusions: Key biomarkers and pathways identified in the present study may enhance the comprehend of the molecular mechanisms underlying hepatocarcinogenesis. Additionally, mRNA expression of PRC1 and TOP2A may serve as potential diagnostic and prognostic biomarkers for HBV-related HCC.

A low DNA methylation epigenotype in lung squamous cell carcinoma and its association with idiopathic pulmonary fibrosis and poorer prognosis

Patients with idiopathic pulmonary fibrosis (IPF) have higher risk of developing lung cancer, for example, squamous cell carcinoma (SCC), and show poor prognosis, while the molecular basis has not been fully investigated. Here we conducted DNA methylome analysis of lung SCC using 20 SCC samples with/without IPF, and noncancerous lung tissue samples from smokers/nonsmokers, using Infinium HumanMethylation 450K array. SCC was clustered into low- and high-methylation epigenotypes by hierarchical clustering analysis. Genes hypermethylated in SCC significantly included genes targeted by polycomb repressive complex in embryonic stem cells, and genes associated with Gene Ontology terms, for example, "transcription" and "cell adhesion," while genes hypermethylated specifically in high-methylation subgroup significantly included genes associated with "negative regulation of growth." Low-methylation subgroup significantly correlated with IPF (78%, vs. 17% in high-methylation subgroup, p = 0.04), and the correlation was validated by additional Infinium analysis of SCC samples (n = 44 in total), and data from The Cancer Genome Atlas (n = 390). The correlation between low-methylation subgroup and IPF was further validated by quantitative methylation analysis of marker genes commonly hypermethylated in SCC (HOXA2, HOXA9 and PCDHGB6), and markers specifically hypermethylated in high-methylation subgroup (DLEC1, CFTR, MT1M, CRIP3 and ALDH7A1) in 77 SCC cases using pyrosequencing (p = 0.003). Furthermore, low-methylation epigenotype significantly correlated with poorer prognosis among all SCC patients, or among patients without IPF. Multivariate analysis showed that low-methylation epigenotype is an independent predictor of poor prognosis. These may suggest that lung SCC could be stratified into molecular subtypes with distinct prognosis, and low-methylation lung SCC that significantly correlates with IPF shows unfavorable outcome.

ZNF479 downregulates metallothionein-1 expression by regulating ASH2L and DNMT1 in hepatocellular carcinoma

Decreased expression of metallothionein-1 (MT-1) is associated with a poor prognosis in hepatocellular carcinoma (HCC). Here, we found that MT-1 expression was suppressed by 14-3-3ε, and MT-1 overexpression abolished 14-3-3ε-induced cell proliferation and tumor growth. We identified that 14-3-3ε induced expression of ZNF479, a novel potential transcriptional regulator by gene expression profiling and ZNF479 contributed to 14-3-3ε-suppressed MT-1 expression. ZNF479 induced the expression of DNMT1, UHRF1, and mixed-lineage leukemia (MLL) complex proteins (ASH2L and Menin), and increased tri-methylated histone H3 (H3K4me3) levels, but suppressed H3K4 (H3K4me2) di-methylation. ZNF479-suppressed MT-1 expression was restored by silencing of ASH2L and DNMT1. Furthermore, ZNF479 expression was higher in HCC tissues than that in the non-cancerous tissues. Expression analyses revealed a positive correlation between the expression of ZNF479 and DNMT1, UHRF1, ASH2L, and Menin, and an inverse correlation with that of ZNF479, ASH2L, Menin, and MT-1 isoforms. Moreover, correlations between the expression of ZNF479 and its downstream factors were more pronounced in HCC patients with hepatitis B. Here, we found that ZNF479 regulates MT-1 expression by modulating ASH2L in HCC. Approaches that target ZNF479/MLL complex/MT-1 or related epigenetic regulatory factors are potential therapeutic strategies for HCC.

Overexpressed long noncoding RNA TUG1 affects the cell cycle, proliferation, and apoptosis of pancreatic cancer partly through suppressing RND3 and MT2A

Background

Long noncoding RNAs (lncRNAs) are involved in various human diseases, including cancers. However, their mechanisms remain undocumented. We investigated alterations in lncRNA that may be related to pancreatic cancer (PC) through analysis of microarray data.

Methods

In the present study, quantitative real-time PCR analysis was used to examine the expression of taurine upregulated 1 (TUG1) in PC tissue samples and PC cell lines. In PC cell lines, MTT assays, colony formation assays, and flow cytometry were used to investigate the effects of TUG1 on proliferation, cell cycle regulation, and apoptosis. Moreover, we established a xenograft model to assess the effect of TUG1 on tumor growth in vivo. The molecular mechanism of potential target genes was detected through nuclear separation experiments, RNA immunoprecipitation (RIP), chromatin immunoprecipitation assays (ChIP), and other experimental methods.

Results

The findings suggest that the abnormally high expression of TUG1 in PC tissues was associated with tumor size and pathological stage. Knockdown of TUG1 blocked the cell cycle and accelerated apoptosis, thereby inhibiting the proliferation of PC cells. In addition, RIP experiments showed that TUG1 can recruit enhancer of zeste homolog 2 (EZH2) to the promoter regions of Rho family GTPase 3 (RND3) and metallothionein 2A (MT2A) and inhibit their expression at the transcriptional level. Furthermore, ChIP experiments demonstrated that EZH2 could bind to the promoter regions of RND3 and MT2A. The knockdown of TUG1 reduced this binding capacity.

Conclusion

In conclusion, our data suggest that TUG1 may regulate the expression of PC-associated tumor suppressor genes at the transcriptional level and these may become potential targets for the diagnosis and treatment of PC.

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.

Pulmonary arterial hypertension and the potential roles of metallothioneins: A focused review

The pathophysiology of pulmonary arterial hypertension (PAH) is underlined by cell proliferation and vasoconstriction of pulmonary arterioles this involves multiple molecular factors or proteins, but it is not clear what the exact roles of these factors/proteins are. In addition, there may be other factors/proteins that have not been identified that contribute to PAH pathophysiology. Therefore, research has focused on investigating novel role players, in order to facilitate a better understanding of how PAH develop. Evidence suggest that mitochondrial regulators are key role players in PAH pathophysiology, but regulators that have not received sufficient attention in PAH are metallothioneins (MTs). In PAH patients, MT expression is elevated compared to healthy individuals, suggesting that MTs may be possible biomarkers. In other disease-models, MTs have been shown to regulate cell proliferation and vasoconstriction, processes that are instrumental in PAH pathophysiology. Due to the involvement of these processes in PAH pathophysiology and the ability of MTs to modulate them, this paper propose that cellular MTs may also play a role in PAH development. This paper suggests that PAH-research should perhaps begin to investigate the involvement of cellular MTs in the development of PAH.

MiR-545-3p/MT1M axis regulates cell proliferation, invasion and migration in hepatocellular carcinoma

Studies have shown that metallothionein 1 M (MT1M) is a tumor suppressor gene which is frequently down-regulated in human hepatocellular carcinoma (HCC). The methylation of MT1M promoter region is one of the important transcriptional regulation mechanisms that contribute to the loss of its expression. In our study, we found that there are still half of the 55 HCC tumor tissues in our cohort do not share the promoter methylation of MT1M. So, we speculated there maybe another mechanism participating in the downregulation of MT1M in HCC. Then, we provided evidences that miR-545-3p, which served as a tumor promoter, post-transcriptionally regulate MT1M in HCC through binding to its untranslated region (3'UTR). Taking together, we investigated the role of miR-545-3p in the process of HCC through regulating MT1M.

Metallothionein 1 family profiling identifies MT1X as a tumor suppressor involved in the progression and metastastatic capacity of hepatocellular carcinoma

Metallothionein 1 (MT1s) is a family of cysteine-rich proteins with diverse functions such as metal homeostasis, oxidative stress, and carcinogenesis. However, its involvement in hepatocellular carcinoma (HCC) remains not fully understood. We aimed to explore the contribution of the individual member of MT1s to HCC. Its member mRNA levels were determined in cohort 1 of normal (n = 30), cirrhotic (n = 30), peritumoral (n = 135), and HCC (n = 135). In cohort 1, seven of eight members were down-regulated during the transition from normal liver to HCC, and only MT1G and MT1X were correlated with tumor features and outcomes. The MT1X was selected to be further stained in cohort 2 consisting of a series of liver nodules (15 normal livers, 33 cirrhotic livers, 12 dysplastic nodules, 31 HCC, and 9 HCC metastasis), and in cohort 3 (HCC, n = 85). In cohort 2, MT1X immunoreactivity was reduced in HCC and lost in metastatic HCC and showed good diagnostic performance for HCC (AUC = 0.754, 95%IC = 0.659-0.849). In cohort 3, MT1X expression in peritumoral tissues was independent predictor for HCC (recurrence free survival: HR = 0.34, 95%CI = 0.17-0.66; overall survival: HR = 0.32, 95%CI = 0.16-0.60). Moreover, we found that ectopic overexpression of MT1X delayed G1/S progression of cell cycle and promoted apoptosis in HCC cells in vitro, and suppressed tumor growth and lung metastasis in nude mice in vivo. We further demonstrated that MT1X induces cell cycle arrest and apoptosis by inactivating NF-κB signaling in HCC. In conclusion, MT1X may serve as a candidate of prognostic indicator and inhibits the progression and metastasis of HCC.

The roles of metallothioneins in carcinogenesis

Metallothioneins (MTs) are small cysteine-rich proteins that play important roles in metal homeostasis and protection against heavy metal toxicity, DNA damage, and oxidative stress. In humans, MTs have four main isoforms (MT1, MT2, MT3, and MT4) that are encoded by genes located on chromosome 16q13. MT1 comprises eight known functional (sub)isoforms (MT1A, MT1B, MT1E, MT1F, MT1G, MT1H, MT1M, and MT1X). Emerging evidence shows that MTs play a pivotal role in tumor formation, progression, and drug resistance. However, the expression of MTs is not universal in all human tumors and may depend on the type and differentiation status of tumors, as well as other environmental stimuli or gene mutations. More importantly, the differential expression of particular MT isoforms can be utilized for tumor diagnosis and therapy. This review summarizes the recent knowledge on the functions and mechanisms of MTs in carcinogenesis and describes the differential expression and regulation of MT isoforms in various malignant tumors. The roles of MTs in tumor growth, differentiation, angiogenesis, metastasis, microenvironment remodeling, immune escape, and drug resistance are also discussed. Finally, this review highlights the potential of MTs as biomarkers for cancer diagnosis and prognosis and introduces some current applications of targeting MT isoforms in cancer therapy. The knowledge on the MTs may provide new insights for treating cancer and bring hope for the elimination of cancer.

Hypomethylated Ubiquitin-Conjugating Enzyme2 Q1 (UBE2Q1) Gene Promoter in the Serum Is a Promising Biomarker for Hepatitis B Virus-Associated Hepatocellular Carcinoma

Aberrant DNA methylation, which can be detected in circulating cell-free DNA (cfDNA), is one of the major epigenetic alterations in hepatocellular carcinoma (HCC). UBE2Q1, a putative member of the ubiquitin-conjugating enzyme family, might play substantial roles in tumorigenesis. However, the methylation status of the UBE2Q1 gene in HCC remains unknown. We aimed to determine the methylation status of the UBE2Q1 gene promoter and to evaluate its potential clinical significance for HCC detection. The methylation-specific polymerase chain reaction (MSP) assay was used to detect the UBE2Q1 gene methylation status in serum samples from 80 patients with hepatitis B virus (HBV)-related HCC, 40 patients with liver cirrhosis (LC), 40 patients with chronic hepatitis B (CHB), and 20 healthy controls (HCs). Significantly lower methylation frequencies were detected in HCC patients (33.75%) compared with LC patients (55.00%, p = 0.026) and CHB patients (60.00%, p = 0.006) and HCs (65.00%, p = 0.011). Hypomethylation of the UBE2Q1 gene was negatively associated with the tumor node metastasis stage (r_s = -0.30, p = 0.008). The UBE2Q1 gene methylation status combined with alpha fetoprotein using cut-off points of 20, 200 and 400 ng/ml showed sensitivity and specificity values of 58.8% and 75.0%, 53.8% and 87.5%, and 37.5% and 88.7%, respectively, and yielded a significantly increased area under the ROC curve (0.720, 0.760 and 0.694, respectively) for discriminating HCC from LC and CHB. Our study results suggest that hypomethylation of the UBE2Q1 gene promoter is a potential biomarker for detecting HBV-associated HCC.

Metallothionein 1M suppresses tumorigenesis in hepatocellular carcinoma

Members of the metallothionein (MT) family are involved in metal detoxifcation and in the protection of cells against certain electrophilic carcinogens. In present study, it was found that MT1M was downregulated in more than 77.1% (91/118) of hepatocellular carcinoma (HCC) tissues compared with adjacent non-tumor tissues. Furthermore, overexpression of MT1M inhibited cell viability, colony formation, cell migration and invasion in HCC cell lines and tumor cell growth in xenograft nude mice, and activated cell apoptosis in HCC cell lines. In addition, immunohistochemistry analysis showed MT1M was negative or weak staining in tumor tissues but moderate or strong staining in adjacent non-tumor tissues. The sensitivity and specificity of MT1M for HCC diagnosis were 76.27% and 89.83%, respectively. In conclusion, MT1M was identified as a potential tumor marker for HCC and may serve as a useful therapeutic agent for HCC gene therapy.

Metallothionein: a Potential Link in the Regulation of Zinc in Nutritional Immunity

Nutritional immunity describes mechanisms for withholding essential transition metals as well as directing the toxicity of these metals against infectious agents. Zinc is one of these transition elements that are essential for both humans and microbial pathogens. At the same time, Zn can be toxic both for man and microbes if its concentration is higher than the tolerance limit. Therefore a "delicate" balance of Zn must be maintained to keep the immune cells surveilling while making the level of Zn either to starve or to intoxicate the pathogens. On the other hand, the invading pathogens will exploit the host Zn pool for its survival and replication. Apparently, different sets of protein in human and bacteria are involved to maintain their Zn need. Metallothionein (MT)-a group of low molecular weight proteins, is well known for its Zn-binding ability and is expected to play an important role in that Zn balance at the time of active infection. However, the differences in structural, functional, and molecular control of biosynthesis between human and bacterial MT might play an important role to determine the proper use of Zn and the winning side. The current review explains the possible involvement of human and bacterial MT at the time of infection to control and exploit Zn for their need.

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.

Gene expression profiling, pathway analysis and subtype classification reveal molecular heterogeneity in hepatocellular carcinoma and suggest subtype specific therapeutic targets

A very low 5-year survival rate among hepatocellular carcinoma (HCC) patients is mainly due to lack of early stage diagnosis, distant metastasis and high risk of postoperative recurrence. Hence ascertaining novel biomarkers for early diagnosis and patient specific therapeutics is crucial and urgent. Here, we have performed a comprehensive analysis of the expression data of 423 HCC patients (373 tumors and 50 controls) downloaded from The Cancer Genome Atlas (TCGA) followed by pathway enrichment by gene ontology annotations, subtype classification and overall survival analysis. The differential gene expression analysis using non-parametric Wilcoxon test revealed a total of 479 up-regulated and 91 down-regulated genes in HCC compared to controls. The list of top differentially expressed genes mainly consists of tumor/cancer associated genes, such as AFP, THBS4, LCN2, GPC3, NUF2, etc. The genes over-expressed in HCC were mainly associated with cell cycle pathways. In total, 59 kinases associated genes were found over-expressed in HCC, including TTK, MELK, BUB1, NEK2, BUB1B, AURKB, PLK1, CDK1, PKMYT1, PBK, etc. Overall four distinct HCC subtypes were predicted using consensus clustering method. Each subtype was unique in terms of gene expression, pathway enrichment and median survival. Conclusively, this study has exposed a number of interesting genes which can be exploited in future as potential markers of HCC, diagnostic as well as prognostic and subtype classification may guide for improved and specific therapy.

Comprehensive and Integrative Genomic Characterization of Hepatocellular Carcinoma

Liver cancer has the second highest worldwide cancer mortality rate and has limited therapeutic options. We analyzed 363 hepatocellular carcinoma (HCC) cases by whole-exome sequencing and DNA copy number analyses, and we analyzed 196 HCC cases by DNA methylation, RNA, miRNA, and proteomic expression also. DNA sequencing and mutation analysis identified significantly mutated genes, including LZTR1, EEF1A1, SF3B1, and SMARCA4. Significant alterations by mutation or downregulation by hypermethylation in genes likely to result in HCC metabolic reprogramming (ALB, APOB, and CPS1) were observed. Integrative molecular HCC subtyping incorporating unsupervised clustering of five data platforms identified three subtypes, one of which was associated with poorer prognosis in three HCC cohorts. Integrated analyses enabled development of a p53 target gene expression signature correlating with poor survival. Potential therapeutic targets for which inhibitors exist include WNT signaling, MDM4, MET, VEGFA, MCL1, IDH1, TERT, and immune checkpoint proteins CTLA-4, PD-1, and PD-L1.

Origin, Function, and Fate of Metallothionein in Human Blood

Toxic heavy metals, toxic organic compounds, reactive oxygen species (ROS), infections, and temperature are well-known metallothionein (MT) inducers in human blood. The current review aims to summarize synthesis, function, and fate of human blood MT in response to the known MT inducers. Part of the MTs that are synthesized in different organs such as the liver, kidney, and spleen is transported and stored in different blood cells and in plasma. Cells of the circulatory system also synthesize MT. From the circulation, MT returns to the kidney where the metal-bound MTs are degraded to release the metal ion that in turn induces MT expression therein. The blood MTs play important roles in metal detoxification, transportation, and storage. By neutralizing ROS, MTs protect blood cells from oxidative stress-induced cytotoxicity and genotoxicity. Arguably, MTs are also involved in immune suppression. Given the permeating distribution of blood MT throughout the body as well as its diverse role in the protection against harmful environmental factors and in metal homeostasis, MT could be better recognized as a major public health protein.

Dysregulation of metallothionein and circadian genes in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the major threat to human health, and disruption of circadian clock genes is implicated in hepatocarcinogenesis. This study examined the dysregulation of metallothioneins and circadian genes in achieved human HCC (n = 24), peri-HCC tissues (n = 24) as compared with normal human livers (n = 36). Total RNA was extracted and reverse transcribed. Real-time RT-qPCR was performed to determine the expression of genes of interest. The results demonstrated the downregulation of metallothionein-1 (MT-1), MT-2, and metal transcription factor-1 (MFT-1) in human HCC as compared with Peri-HCC and normal tissues. MTs are a biomarker for HCC and have typical circadian rhythms; the expression of major circadian clock genes was also determined. HCC produced a dramatic decrease in the expression of core clock genes, circadian locomotor output cycles kaput (Clock) and brain and muscle Arnt-like protein 1 (Bmal1), and decreased the expression of the clock feedback control genes, Periods (Per1, Per2) and Cryptochromes (Cry1, Cry2). On the other hand, the expression of clock target genes nuclear orphan receptor factor protein (Nr1d1) and D-box-binding protein (Dbp) was upregulated as compared with Peri-HCC and normal livers. Peri-HCC also had mild alterations in these gene expressions. In summary, the present study clearly demonstrated the dysregulation of MTs and circadian clock genes in human HCC, which could provide the information of targeting MT and circadian clock in HCC management.

MiR-24-3p enhances cell growth in hepatocellular carcinoma by targeting metallothionein 1M

Dysregulation of microRNAs has been demonstrated to contribute to malignant progression of cancers, including hepatocellular carcinoma (HCC). MiR-24-3p was previously reported to be significantly upregulated in HCC. However, the potential role and mechanism of action of miR-24-3p in the initiation and progression of HCC remain largely unknown. Quantitative reverse transcription polymerase chain reaction demonstrated that miR-24-3p was significantly upregulated in HCC tumor tissues compared with nontumor tissues. The cell viability, colony formation assay, and tumorigenicity assays in nude mice showed that miR-24-3p could enhance HCC cell growth in vitro and in vivo. Metallothionein 1M was verified as an miR-24-3p target gene by using dual-luciferase reporter assays, quantitative reverse transcription polymerase chain reaction, and Western blotting, which was involved in miR-24-3p regulated HCC cell growth. These results indicated that miR-24-3p plays an important role in the initiation and progression of HCC by targeting metallothionein 1M, and the miR-24-3p/metallothionein 1M pathway may contribute to the development of novel therapeutic strategies for HCC in the future.

Epigenetic Upregulation of Metallothionein 2A by Diallyl Trisulfide Enhances Chemosensitivity of Human Gastric Cancer Cells to Docetaxel Through Attenuating NF-κB Activation

AIMS

Metallothionein 2A (MT2A) and nuclear factor-kappaB (NF-κB) are both involved in carcinogenesis and cancer chemosensitivity. We previously showed decreased expression of MT2A and IκB-α in human gastric cancer (GC) associated with poor prognosis of GC patients. The present study investigated the effect of diallyl trisulfide (DATS), a garlic-derived compound, and docetaxel (DOC) on regulation of MT2A in relation to NF-κB in GC cells.

RESULTS

DATS attenuated NF-κB signaling in GC cells, resulting in G2/M cell cycle arrest and apoptosis, culminating in the inhibition of cell proliferation and tumorigenesis in nude mice. The anti-GC effect of DATS was attributable to its capacity to epigenetically upregulate MT2A, which in turn enhanced transcription of IκB-α to suppress NF-κB activation in GC cells. The combination of DATS with DOC exhibited a synergistic anti-GC activity accompanied by MT2A upregulation and NF-κB inactivation. Histopathologic analysis of GC specimens from patients showed a significant increase in MT2A expression following DOC treatment. GC patients with high MT2A expression in tumor specimens showed significantly improved response to chemotherapy and prolonged survival compared with those with low MT2A expression in tumors.

INNOVATION AND CONCLUSION

We conclude that DATS exerts its anti-GC activity and enhances chemosensitivity of GC to DOC by epigenetic upregulation of MT2A to attenuate NF-κB signaling. Our findings delineate a mechanistic basis of MT2A/NF-κB signaling for DATS- and DOC-mediated anti-GC effects, suggesting that MT2A may be a chemosensitivity indicator in GC patients receiving DOC-based treatment and a promising target for more effective treatment of GC by combination of DATS and DOC. Antioxid. Redox Signal. 24, 839-854.

In silico and experimental analyses predict the therapeutic value of an EZH2 inhibitor GSK343 against hepatocellular carcinoma through the induction of metallothionein genes

There are currently no effective molecular targeted therapies for hepatocellular carcinoma (HCC), the third leading cause of cancer-related death worldwide. Enhancer of zeste homolog 2 (EZH2), a histone H3 lysine 27 (H3K27)-specific methyltransferase, has been emerged as novel anticancer target. Our previous study has demonstrated that GSK343, an S-adenosyl-L-methionine (SAM)-competitive inhibitor of EZH2, induces autophagy and enhances drug sensitivity in cancer cells including HCC. In this study, an in silico study was performed and found that EZH2 was overexpressed in cancerous tissues of HCC patients at both gene and protein levels. Microarray analysis and in vitro experiments indicated that the anti-HCC activity of GSK343 was associated with the induction of metallothionein (MT) genes. In addition, the negative association of EZH2 and MT1/MT2A genes in cancer cell lines and tissues was found in public gene expression database. Taken together, our findings suggest that EZH2 inhibitors could be a good therapeutic option for HCC, and induction of MT genes was associated with the anti-HCC activity of EZH2 inhibitors.

Screening and verification of proteins that interact with HSPC238

HSPC238 is a recently identified tumor suppressor and demonstrates ubiquitin ligase E3 enzyme activity. HSPC238 was found to be significantly downregulated in human hepatocellular carcinoma (HCC) in vivo and to inhibit the proliferation and invasion of hepatoma cells in vitro; however, the underlying molecular mechanism is largely unknown. In the present study, we screened for and identified proteins that physically interact with HSPC238. A bait vector for yeast two-hybrid was constructed with human HSPC238 gene cDNA. Yeast two-hybrid screening was performed using a human fetal liver cDNA library. Multiple reporter gene assays, DNA sequencing and BLAST comparison analysis were performed on positive clones. Protein interaction of screened candidates with HSPC238 was further validated by confocal microscopy, co-immunoprecipitation and pull-down assays. Yeast two-hybrid screening demonstrated 124 positive clones. Multiple reporter gene assays with LacZ, HIS and ADE2 selective media identified 12 genes. Further co-localization, co-immunoprecipitation and pull-down assays demonstrated that HMOX1, RPS27A, ubiquitinB and MT2A interacted with HSPC238. These four proteins are involved in tumor development and progression, and are associated with the ubiquitin-proteasome pathway. Our results suggest that HSPC238 may play a tumor suppressor role and interact with these proteins via the ubiquitin-proteasome pathway. The identification and validation of proteins interacting with HSP238 may lead to the discovery of novel mechanisms through which HSPC238 suppresses tumorigenesis in human hepatocellular carcinoma.

Placental DNA Methylation Related to Both Infant Toenail Mercury and Adverse Neurobehavioral Outcomes

BACKGROUND

Prenatal mercury (Hg) exposure is associated with adverse child neurobehavioral outcomes. Because Hg can interfere with placental functioning and cross the placenta to target the fetal brain, prenatal Hg exposure can inhibit fetal growth and development directly and indirectly.

OBJECTIVES

We examined potential associations between prenatal Hg exposure assessed through infant toenail Hg, placental DNA methylation changes, and newborn neurobehavioral outcomes.

METHODS

The methylation status of > 485,000 CpG loci was interrogated in 192 placental samples using Illumina's Infinium HumanMethylation450 BeadArray. Hg concentrations were analyzed in toenail clippings from a subset of 41 infants; neurobehavior was assessed using the NICU Network Neurobehavioral Scales (NNNS) in an independent subset of 151 infants.

RESULTS

We identified 339 loci with an average methylation difference > 0.125 between any two toenail Hg tertiles. Variation among these loci was subsequently found to be associated with a high-risk neurodevelopmental profile (omnibus p-value = 0.007) characterized by the NNNS. Ten loci had p < 0.01 for the association between methylation and the high-risk NNNS profile. Six of 10 loci reside in the EMID2 gene and were hypomethylated in the 16 high-risk profile infants' placentas. Methylation at these loci was moderately correlated (correlation coefficients range, -0.33 to -0.45) with EMID2 expression.

CONCLUSIONS

EMID2 hypomethylation may represent a novel mechanism linking in utero Hg exposure and adverse infant neurobehavioral outcomes.

Positive and negative regulators of the metallothionein gene (review)

Metallothioneins (MTs) are metal-binding proteins involved in diverse processes, including metal homeostasis and detoxification, the oxidative stress response and cell proliferation. Aberrant expression and silencing of these genes are important in a number of diseases. Several positive regulators of MT genes, including metal-responsive element-binding transcription factor (MTF)-1 and upstream stimulatory factor (USF)-1, have been identified and mechanisms of induction have been well described. However, the negative regulators of MT genes remain to be elucidated. Previous studies from the group of the present review have revealed that the hematopoietic master transcription factor, PU.1, directly represses the expression levels of MT genes through its epigenetic activities, and upregulation of MT results in the potent inhibition of myeloid differentiation. The present review focuses on PU.1 and several other negative regulators of this gene, including PZ120, DNA methyltransferase 3a with Mbd3 and Brg1 complex, CCAAT enhancer binding protein α and Ku protein, and describes the suppression of the MT genes through these transcription factors.