metallothionein and Neoplasms

Metallothionein-2 (MT-2) was originally discovered as a mediator of zinc homeostasis and cadmium detoxification. However, MT-2 has recently received increased attention because altered expression of MT-2 is closely related to various diseases such as asthma and cancers. Several pharmacological strategies have been developed to inhibit or modify MT-2, revealing its potential as drug target in diseases. Therefore, a better understanding of the mechanisms of MT-2 action is warranted to improve drug development for potential clinical applications. In this review, we highlight recent advances in determining the protein structure, regulation, binding partners, and new functions of MT-2 in inflammatory diseases and cancers.

Topics: Cadmium; Humans; Metallothionein; Neoplasms; Zinc

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.

Topics: Antineoplastic Agents; Biomarkers, Tumor; Carcinogenesis; Disease Progression; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; Ions; Metallothionein; Metals; Neoplasm Staging; Neoplasms; Prognosis; Protein Isoforms

Metabolic dysregulation is an appreciated hallmark of cancer and a target for therapeutic intervention. Cellular metabolism involves a series of oxidation/reduction (redox) reactions that yield the energy and biomass required for tumor growth. Cells require diverse molecular species with constituent sulfur atoms to facilitate these processes. For humans, this sulfur is derived from the dietary consumption of the proteinogenic amino acids cysteine and methionine, as only lower organisms (e.g., bacteria, fungi, and plants) can synthesize them de novo. In addition to providing the sulfur required to sustain redox chemistry, the metabolism of these sulfur-containing amino acids yield intermediate metabolites that constitute the cellular antioxidant system, mediate inter- and intracellular signaling, and facilitate the epigenetic regulation of gene expression, all of which contribute to tumorigenesis.

Topics: Animals; Carcinogenesis; Chelating Agents; Cysteine; Humans; Metallothionein; Methionine; Mitogen-Activated Protein Kinase Kinases; Neoplasms; Oxidation-Reduction; Oxidative Stress; Sulfhydryl Compounds; Sulfur

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.

Topics: Animals; Epigenesis, Genetic; Humans; Metallothionein; Neoplasms; Protein Isoforms

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.

Topics: Carcinogenesis; Humans; Metallothionein; Neoplasms

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

Topics: Biomarkers, Tumor; Case-Control Studies; Disease-Free Survival; Female; Humans; Intestinal Neoplasms; Kaplan-Meier Estimate; Kidney Neoplasms; Liver Neoplasms; Male; Metallothionein; Neoplasms; Ovarian Neoplasms; Predictive Value of Tests; Prognosis; Proportional Hazards Models; Urinary Bladder Neoplasms

Metallothionein is cysteine-rich low molecular mass protein. The involvement of MT in many physiological and pathophysiological processes such as apoptosis, proliferation, angiogenesis, and the detoxification of heavy metals suggested participation of this protein in carcinogenesis and tumor therapy. Depending on the type of tissue and classification of carcinoma various it was observed relation between MT expression and tumor type, stage, grade, poor prognosis and body resistance to radiotherapy and chemotherapy. MT in tumor cell plays important role in defense mechanism against the effect of radiation by inhibiting the processes that lead to the apoptosis. A number of studies have shown an increased expression of MT in various human tumors of larynx, pancreas, kidney, uterus and breast, whereas lower MT expression was detected in liver tumors. Variable MT expression was detected in case of thyroid, prostate, lung, stomach and central nervous system tumors. Also MT plays crucial role in the cytostatics treatment. MT can bind cis-platinum compounds and removes them from the cells, which may lead to multidrug resistance. However, the same functions of MT protect against the negative effects of chemotherapeutic treatment. It is especially important in case of heart cells. Analysis of MT expression in tumor cells may be useful in choosing method of treatment. It is difficult to determine whether increased expression of MT is only a inducing factor of the development of the carcinogenesis, its malignances and multidrug resistance, or it is a factor inhibiting the induction and development of cancer.

Topics: Antineoplastic Agents; Apoptosis; Carcinogenesis; Cell Transformation, Neoplastic; Humans; Metallothionein; Neoplasms

Cardiotoxicity is a serious complication of anticancer therapy by anthracycline antibiotics. Except for intercalation into DNA/RNA structure, inhibition of DNA-topoisomerase and histone eviction from chromatin, the main mechanism of their action is iron-mediated formation of various forms of free radicals, which leads to irreversible damage to cancer cells. The most serious adverse effect of anthracyclines is, thus, cardiomyopathy leading to congestive heart failure, which is caused by the same mechanisms. Here, we briefly summarize the basic types of free radicals formed by anthracyclines and the main processes how to scavenge them. From these, the main attention is paid to metallothioneins. These low-molecular cysteine-rich proteins are introduced and their functions and properties are reviewed. Further, their role in detoxification of metals and drugs is discussed. Based on these beneficial roles, their use as a new therapeutic agent against oxidative stress and for cardioprotection is critically evaluated with respect to their ability to increase chemoresistance against some types of commonly used cytostatics.

Topics: Animals; Anthracyclines; Antibiotics, Antineoplastic; Cardiomyopathies; Cardiotonic Agents; Drug Resistance, Neoplasm; Free Radical Scavengers; Free Radicals; Heart Failure; Humans; Metallothionein; Neoplasms; Oxidative Stress

Metallothioneins (MTs), low molecular mass cysteine-rich proteins, which are able to bind up to 20 monovalent and up to 7 divalent heavy metal ions are widely studied due to their functions in detoxification of metals, scavenging free radicals and cells protection against the oxidative stress. It was found that the loss of the protective effects of MT leads to an escalation of pathogenic processes and carcinogenesis. The most extensive area is MTs expression for oncological applications, where the information about gene patterns is helpful for the identification biological function, resistance to drugs and creating the correct chemotherapy. In other medical applications the effect of oxidative stress to cell lines exposed to heavy metals and hydrogen peroxide is studied as well as influence of drugs and cytokines on MTs expression and MTs expression in the adipose tissue. The precise detection of low metallothionein concentrations and its isoforms is necessary to understand the connection between quantity and isoforms of MTs to size, localization and type of cancer. This information is necessary for well-timed therapy and increase the chance to survival. Microarray chips appear as good possibility for finding all information about expression of MTs genes and isoforms not only in cancer, but also in other diseases, especially diabetes, obesity, cardiovascular diseases, ageing, osteoporosis, psychiatric disorders and as the effects of toxic drugs and pollutants, which is discussed in this review.

Topics: Animals; Humans; Metallothionein; Microarray Analysis; Neoplasms; Oxidative Stress

Metallothioneins (MTs) are low molecular weight proteins, which are present in almost all types of organisms. In mammals, four main MT isoforms designated from MT-1 to MT-4 were identified. Their biological role, according to their characteristic structure, was shown to be mostly associated with cellular metabolism of metal ions, especially zinc. Moreover, the available evidence suggests broad regulatory properties of MTs in the control of cell senescence and various pathological processes including neurodegeneration, cardiovascular pathology, metabolic disorders, and various malignancies. This extensive review provides general in formation on the structure of MT family members and the cellular functions of MT-1, MT-2, and MT-4 isoforms as well as insights into divergent biological roles of MT-3. Due to the involvement of MT molecules in various processes related to carcinogenesis, an organ-specific presentation of current data concerning their potential impact on the progression of various tumors is given. The regulatory role of MT family members in the function of the immune system is also discussed in depth.

Topics: Amino Acid Sequence; Animals; Carcinogenesis; Humans; Immunity; Metallothionein; Metallothionein 3; Molecular Sequence Data; Neoplasms; Nerve Tissue Proteins

Mammalian metallothionein-2A (MT2A) has received considerable attention in recent years due to its crucial pathophysiological role in anti-oxidant, anti-apoptosis, detoxification and anti-inflammation. For many years, most studies evaluating the effects of MT2A have focused on reactive oxygen species (ROS), as second messengers that lead to oxidative stress injury of cells and tissues. Recent studies have highlighted that oxidative stress could activate mitogen-activated protein kinases (MAPKs), and MT2A, as a mediator of MAPKs, to regulate the pathogenesis of various diseases. However, the molecule mechanism of MT2A remains elusive. A deeper understanding of the functional, biochemical and molecular characteristics of MT2A would be identified, in order to bring new opportunities for oxidative stress therapy.

Topics: Animals; Cardiovascular Diseases; Humans; MAP Kinase Signaling System; Metallothionein; Neoplasms; Nervous System Diseases; Oxidative Stress

Metallothioneins (MTs) are a class of metal-binding proteins characterized by a high cysteine content and low molecular weight. MTs play an important role in metal metabolism and protect cells against the toxic effects of radiation, alkylating agents and oxygen free radicals. The evidence that individual genetic characteristics of MTs play an important role in physiological and pathological processes associated with antioxidant defense and detoxification inspired targeted studies of genetic polymorphisms in a clinical context. In recent years, common MT polymorphisms were identified and associated with, particularly, western lifestyle diseases such as cancer, complications of atherosclerosis, and type 2 diabetes mellitus along with related complications. This review summarizes all evidence regarding MT polymorphisms of major human MTs (MT1, MT2, MT3 and MT4), their relation to pathological processes, and outlines specific applications of MTs as a set of genetic markers for certain pathologies.

Topics: Cardiomyopathies; Diabetes Mellitus, Type 2; Gene Expression Regulation; Humans; Inflammation; Metallothionein; Multigene Family; Neoplasms; Polymorphism, Single Nucleotide; Protein Isoforms

Metallothioneins (MTs) are a family of universal, small proteins, sharing a high cysteine content and an optimal capacity for metal ion coordination. They take part in a plethora of metal ion-related events (from detoxification to homeostasis, storage, and delivery), in a wide range of stress responses, and in different pathological processes (tumorigenesis, neurodegeneration, and inflammation). The information on both intracellular and extracellular interactions of MTs with other proteins is here comprehensively reviewed. In mammalian kidney, MT1/MT2 interact with megalin and related receptors, and with the transporter transthyretin. Most of the mammalian MT partners identified concern interactions with central nervous system (mainly brain) proteins, both through physical contact or metal exchange reactions. Physical interactions mainly involve neuronal secretion multimers. Regarding metal swap events, brain MT3 appears to control the metal ion load in peptides whose aggregation leads to neurodegenerative disorders, such as Aβ peptide, α-synuclein, and prion proteins (Alzheimer's and Parkinson's diseases, and spongiform encephalopathies, respectively). Interaction with ferritin and bovine serum albumin are also documented. The intercourse of MTs with zinc-dependent enzymes and transcription factors is capable to activate/deactivate them, thus conferring MTs the role of metabolic and gene expression regulators. As some of these proteins are involved in cell cycle and proliferation control (p53, nuclear factor κB, and PKCμ), they are considered in the context of oncogenesis and tumor progression. Only one non-mammalian MT interaction, involving Drosophila MtnA and MtnB major isoforms and peroxiredoxins, has been reported. The prospective use for biomedical applications of the MT-interaction information is finally discussed.

Topics: Animals; Brain; Gene Expression Regulation; Humans; Kidney; Metallothionein; Neoplasms; Neurodegenerative Diseases; Protein Aggregates; Protein Binding; Protein Conformation; Reactive Oxygen Species; Synaptic Transmission

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

Topics: Amino Acid Sequence; Animals; Antineoplastic Agents; Apoptosis; Cadmium; Cell Proliferation; Drug Resistance, Neoplasm; Free Radicals; Glutathione; Humans; Metallothionein; Metals; Models, Molecular; Molecular Sequence Data; Neoplasms

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

Topics: Animals; Antineoplastic Agents; Apoptosis; Biomarkers, Tumor; Cell Proliferation; Humans; Immunomodulation; Metallothionein; Molecular Targeted Therapy; Neoplasm Proteins; Neoplasms; Nitric Oxide; Oxidative Stress; Prognosis; Zinc

The Metallothionein (MT) is a protein which has several interesting biological effects and has been demonstrated increase focus on the role of MT in various biological systems in the past three decades. The studies on the role of MT were limited with few areas like apoptosis and antioxidants in selected organs even fifty years after its discovery. Now acknowledge the exploration of various isoforms of MT such as MT-I, MT-II, MT-III and MT-IV and other isoforms in various biological systems.Strong evidence exists that MT modulates complex diseases and the immune system in the body but the primary function of MT still remains unknown. This review's main objective is to explore the capability to specifically manipulate MT levels in cells and in animals to provide answers regarding how MT could impact those complex disease scenarios.The experimental result mentioned in this review related among MT, zinc, cadmium, diabetic, heart disease, bone retardation, neuro toxicity, kidney dysfunction, cancer, and brain suggest novel method for exploration and contribute significantly to the growing scientist to research further in this field.

Topics: Animals; Bone Diseases, Developmental; Central Nervous System; Diabetes Mellitus; Heart Diseases; Humans; Kidney Diseases; Metallothionein; Neoplasms; Oxidative Stress; Protein Isoforms

The present paper centers on mammalian metallothionein 1 and 2 in relationship to cell and tissue injury beginning with its reaction with Cd²⁺ and then considering its role in the toxicology and chemotherapy of both metals and non-metal electrophiles and oxidants. Intertwined is a consideration of MTs role in tumor cell Zn²⁺ metabolism. The paper updates and expands on our recent review by Petering et al. (Met Ions Life Sci 5:353-398, 2009).

Topics: Animals; Cytotoxins; Humans; Mammals; Metallothionein; Metals; Neoplasms; Oxidants

A tumor stimulates the remodeling of its microenvironment for its own survival. To protect its own growth and induce angiogenesis, the tumor changes the structure of extracellular matrix and the function of existing cells; it thus chemo-attracts immune system cells altering their function. In our study, we discuss the potential markers of tumor microenvironment remodeling. For instance, RCAS1 is a protein responsible for tumor escape from host immunologic surveillance that additionally seems to be involved in the remodeling of the microenvironment. Another protein, metallothionein, which is both anti-apoptotic and pro-proliferative, is also responsible for modulating the response of immune system cells. Most likely, the expression of this protein by the fibroblasts of tumor microenvironment is related to the remodeled phenotype of these cells because of the tumor influence on cancer-associated fibroblasts. Lastly, vimentin is a protein that would appear to be the marker for the mesenchymal transition of cells from the epithelial phenotype. These cells seem to acquire the mesenchymal phenotype to migrate so that they can facilitate the development of metastases. Interestingly, the expression of vimentin has also been observed in the tumor microenvironment as well and may serve as a marker of a remodeled stroma in the process of facilitating tumor spread.

Topics: Antigens, Neoplasm; Biomarkers, Tumor; Fibroblasts; Humans; Macrophages; Mesoderm; Metallothionein; Neoplasm Metastasis; Neoplasms; Tumor Escape; Vimentin

The antiapoptotic, antioxidant, proliferative, and angiogenic effects of metallothionein (MT)-I+II has resulted in increased focus on their role in oncogenesis, tumor progression, therapy response, and patient prognosis. Studies have reported increased expression of MT-I+II mRNA and protein in various human cancers; such as breast, kidney, lung, nasopharynx, ovary, prostate, salivary gland, testes, urinary bladder, cervical, endometrial, skin carcinoma, melanoma, acute lymphoblastic leukemia (ALL), and pancreatic cancers, where MT-I+II expression is sometimes correlated to higher tumor grade/stage, chemotherapy/radiation resistance, and poor prognosis. However, MT-I+II are downregulated in other types of tumors (e.g. hepatocellular, gastric, colorectal, central nervous system (CNS), and thyroid cancers) where MT-I+II is either inversely correlated or unrelated to mortality. Large discrepancies exist between different tumor types, and no distinct and reliable association exists between MT-I+II expression in tumor tissues and prognosis and therapy resistance. Furthermore, a parallel has been drawn between MT-I+II expression as a potential marker for prognosis, and MT-I+II's role as oncogenic factors, without any direct evidence supporting such a parallel. This review aims at discussing the role of MT-I+II both as a prognostic marker for survival and therapy response, as well as for the hypothesized role of MT-I+II as causal oncogenes.

Topics: Biomarkers, Tumor; Humans; Metallothionein; Neoplasms; Prognosis

The discovery of the cadmium (Cd)-binding protein from horse kidney in 1957 marked the birth of research on this low-molecular weight, cysteine-rich protein called metallothionein (MT) in Cd toxicology. MT plays minimal roles in the gastrointestinal absorption of Cd, but MT plays important roles in Cd retention in tissues and dramatically decreases biliary excretion of Cd. Cd-bound to MT is responsible for Cd accumulation in tissues and the long biological half-life of Cd in the body. Induction of MT protects against acute Cd-induced lethality, as well as acute toxicity to the liver and lung. Intracellular MT also plays important roles in ameliorating Cd toxicity following prolonged exposures, particularly chronic Cd-induced nephrotoxicity, osteotoxicity, and toxicity to the lung, liver, and immune system. There is an association between human and rodent Cd exposure and prostate cancers, especially in the portions where MT is poorly expressed. MT expression in Cd-induced tumors varies depending on the type and the stage of tumor development. For instance, high levels of MT are detected in Cd-induced sarcomas at the injection site, whereas the sarcoma metastases are devoid of MT. The use of MT-transgenic and MT-null mice has greatly helped define the role of MT in Cd toxicology, with the MT-null mice being hypersensitive and MT-transgenic mice resistant to Cd toxicity. Thus, MT is critical for protecting human health from Cd toxicity. There are large individual variations in MT expression, which might in turn predispose some people to Cd toxicity.

Topics: Animals; Cadmium; Cell Transformation, Neoplastic; Environmental Pollutants; Humans; Metallothionein; Mice; Neoplasms; Protein Binding

The latest research outcomes indicate that metallothionein (MT) levels in peripheral blood and serum from cancer patients can provide many interesting information about type or clinical stage of the disease, or response to therapy. MT plays a key role in transport of essential heavy metals, detoxification of toxic metals and protection of cells against oxidation stress. Serum MT levels of cancer patients are three times higher than control patients (0.5 microM). The elevated MT levels in cancer cells are probably related to their increased proliferation and protection against apoptosis. Automated electrochemical detection of MT allows its serial analysis in a very small volume with excellent sensitivity, reliability and reproducibility and therefore it can be considered as a new tool for cancer diagnosis (Fig. 4, Ref. 55). Full Text (Free, PDF) www.bmj.sk.

Topics: Biomarkers, Tumor; Electrochemical Techniques; Humans; Metallothionein; Neoplasms

Metallothioneins (MTs) are low molecular, cysteine-rich proteins that have naturally-occurring Zn(2+) in both clusters. They may serve as a reservoir of metals for synthesis of apoenzymes and zinc-finger transcription regulators. MTs are also involved with several important proteins e.g. p53, NF-kappaB, PKCl, and GTPase Rab3A. New biological roles for these proteins have been identified including those needed in the carcinogenic process. However, their use as a predictive marker remains controversial. Several reports have disclosed MTs expression as a prognostic factor for tumor progression and drug resistance in a variety of malignancies particularly breast, prostatic, ovarial, head and neck, non-small cell lung cancer, melanoma, and soft tissue sarcoma. The role of MTs as a tumor disease marker or as a cause of resistance in cancer treatment is reviewed and discussed. Moreover, we describe some analytical methods that were developed to detect MTs.

Topics: Animals; Antineoplastic Agents; Cytostatic Agents; Drug Resistance, Neoplasm; Humans; Metallothionein; Neoplasms

Metallothioneins (MTs) are ubiquitous metal-binding proteins that have been highly conserved throughout evolution. Although their physiological function is not completely understood, they are involved in diverse processes including metal homeostasis and detoxification, the oxidative stress response, inflammation, and cell proliferation. Te human MT gene family consists of at least 18 isoforms, containing pseudogenes as well as genes encoding functional proteins. Most of the MT isoforms can be induced by a wide variety of substances, such as metals, cytokines, and hormones. Different cell types express discrete MT isoforms, which reflects the specifically adapted functions of MTs and a divergence in their regulation. Te aberrant expression of MTs has been described in a number of diseases, including Crohn's disease, cancer, Alzheimer's disease, amyotrophic lateral sclerosis, Menkes disease, and Wilson's disease. Therefore, a thorough understanding of MT gene regulation is imperative. To date, the transcriptional regulation of MTs has primarily been studied in mice. While only four murine MT isoforms exist, the homology between murine and human MTs allows for the evaluation of the regulatory regions in their respective promoters. Here, we review the aberrant expression of MTs in human diseases and the mechanisms that regulate MT1 expression based on an in silico evaluation of transcription factor binding sites.

Topics: Alzheimer Disease; Animals; Crohn Disease; Gene Expression Regulation; Hepatolenticular Degeneration; Humans; Menkes Kinky Hair Syndrome; Metallothionein; Mice; Neoplasms; Phylogeny; Promoter Regions, Genetic

Two research groups produced metallothionein (MT)-I/II knockout mice with null mutation of MT-I and MT-II genes. In 1993, Choo et al. produced MT-I/II knockout mice with a mixed genetic background of 129 Ola and C57BL/6 strains. Palmiter et al. also produced MT-I/II knockout mice with a genetic background of 129/Sv strain in 1994. Subsequently, MT-I/II knockout mice have been used to clarify the biological function and physiological role of MT by many research groups. We were also provided MT-I/II knockout mice from Dr. Choo (Australia). F1 hybrid mice were mated with C57BL/6, and their offspring were back-crossed to C57BL/6 for ten generations. MT-I/II knockout (MT(-/-)) mice and wild-type (MT(+/+)) mice were obtained by mating of those heterozygous (MT(+/-)) mice. We have been investigating the susceptibility of MT-I/II knockout mice to toxicity of harmful factors and some diseases. Our present studies found that MT-I/II knockout mice have an increased sensitivity to harmful metals such as cadmium, mercury, and arsenic, oxidative stress, chemical carcinogenesis and neurodegenerative diseases. These results clearly indicate that MT plays an important role in defense of these toxicities. In this review, we present our findings and summarize recent reports with MT-I/II knockout mice concerning the role of MT as a biological protective factor.

Topics: Animals; Metallothionein; Metals, Heavy; Mice; Mice, Inbred C57BL; Mice, Knockout; Neoplasms; Neurodegenerative Diseases; Oxidative Stress

Chromium exists in many different oxidation states in the environment, Cr(VI) and Cr(III) being the most stable forms. Chromium has been known for over 100 years to be a human carcinogen. The greatest risk of cancer from chromium exposure is associated with Cr(VI). Cr(VI) enters cells via the sulfate anion transporter system and is reduced to intermediate oxidation states, such as Cr(V) and Cr(IV), in the process of forming stable Cr(III) forms. It is known that Cr(VI) affects expression of various genes. Metal responsive element-binding transcription factor-1 (MTF-1) is involved in sensing heavy metal load and the induced transcription of several protective genes, including metallothionein (MT)-I, MT-II, zinc transporter-1, and gamma-glutamylcysteine synthetase. Cr(VI) inhibits zinc-induced MT transcription via modifying transactivation potential of MTF-1. However, the molecular mechanism for the Cr(VI)-mediated inhibition of MTF-1 has not been fully elucidated. In this review, I briefly summarize the previous studies and discuss the current status of research on Cr(VI) toxicity and Cr(VI)-mediated inhibition against transcription.

Topics: Carrier Proteins; Cations; Chromium; DNA Damage; DNA-Binding Proteins; Histone Deacetylases; Metallothionein; Mutagenesis; Neoplasms; NF-kappa B; p300-CBP Transcription Factors; Receptors, Aryl Hydrocarbon; Transcription Factor MTF-1; Transcription Factors; Transcription, Genetic; Transcriptional Activation

Metallothioneins (MT) are low molecular weight proteins present both in normal and in neoplastic cells. They represent the main mechanism of the cell which protects it from action of heavy metal ions and the principal zinc-binding proteins. MT act as controllers of zinc-dependent enzymes, participating, i.a., in cell proliferation processes. The latter is of basic significance also in neoplastic diseases. Despite the relatively short period of studies on the role of MT in neoplastic processes, several data confirm their prognostic significance. Such data have been obtained in studies on expression of the proteins in breast, renal, urinary bladder, ovarian, laryngeal and lung cancers. MT are thought to play certain role in carcinogenesis, as indicated by results of studies on malignant tumors of large bowel, liver and stomach. The frequently noted positive correlation between MT expression and the expression of Ki-67 and PCNA antigens points to role of the proteins in the cell proliferation mechanism. Results collected and discussed in present paper, obtained by various authors and related to the role of MT expression in cells of various malignant tumors suggest a potential for using the protein as a prognostic factor in neoplastic diseases.

Topics: Animals; Biomarkers, Tumor; Female; Humans; Male; Metallothionein; Neoplasms; Prognosis

The metallothionein family is a class of low-molecular-weight, cysteine-rich proteins with high affinity for metal ions. Four major isoforms (metallothionein-1, -2, -3, and -4) have been identified in mammals, involved in many pathophysiological processes, including metal ion homeostasis and detoxification, protection against oxidative damage, cell proliferation and apoptosis, drug and radiotherapy resistance and several aspects of the carcinogenic process. In the present review we examine the expression of metallothionein in different human tumours and its correlation with histopathological variables, tumour cell proliferation or apoptosis, resistance to radiation or chemotherapy, patient survival and prognosis. A variable profile of metallothionein and its isoforms' expression has been observed in different cancer types. Although metallothionein expression has been implicated in carcinogenic evolution, its use as a marker of tumour differentiation, cell proliferation and prognosis predictor remains unclear. Detailed studies focused on the expression of metallothionein isoforms and isotypes in different tumour types could elucidate the role of this group of proteins in the carcinogenic process, delineating its possible clinical significance for the management of patients.

Topics: Apoptosis; Cell Proliferation; Disease-Free Survival; Drug Resistance, Neoplasm; Humans; Metallothionein; Neoplasms; Protein Isoforms; Radiation Tolerance

Targeting unique mRNA molecules using antisense approaches, based on sequence specificity of double-stranded nucleic acid interactions should, in theory, allow for design of drugs with high specificity for intended targets. Antisense-induced degradation or inhibition of translation of a target mRNA is potentially capable of inhibiting the expression of any target protein. In fact, a large number of proteins of widely varied character have been successfully downregulated using an assortment of antisense-based approaches. The most prevalent approach has been to use antisense oligonucleotides (ASOs), which have progressed through the preclinical development stages including pharmacokinetics and toxicological studies. A small number of ASOs are currently in human clinical trials. These trials have highlighted several toxicities that are attributable to the chemical structure of the ASOs, and not to the particular ASO or target mRNA sequence. These include mild thrombocytopenia and hyperglycemia, activation of the complement and coagulation cascades, and hypotension. Dose-limiting toxicities have been related to hepatocellular degeneration leading to decreased levels of albumin and cholesterol. Despite these toxicities, which are generally mild and readily treatable with available standard medications, the clinical trials have clearly shown that ASOs can be safely administered to patients. Alternative chemistries of ASOs are also being pursued by many investigators to improve specificity and antisense efficacy and to reduce toxicity. In the design of ASOs for anticancer therapeutics in particular, the goal is often to enhance the cytotoxicity of traditional drugs toward cancer cells or to reduce the toxicity to normal cells to improve the therapeutic index of existing clinically relevant cancer chemotherapy drugs. We predict that use of antisense ASOs in combination with small molecule therapeutics against the target protein encoded by the antisense-targeted mRNA, or an alternate target in the same or a connected biological pathway, will likely be the most beneficial application of this emerging class of therapeutic agent.

Topics: Animals; Drug Delivery Systems; Genes, bcl-2; HIV Infections; Humans; Metallothionein; Neoplasms; Oligonucleotides, Antisense; Retinitis; Structure-Activity Relationship; Thionucleotides; Tissue Distribution

Metallothioneins (MT) are a group of low-molecular weight, cysteine rich intracellular proteins, which are encoded by a family of genes containing at least 10 functional isoforms in human. The expression and induction of these proteins have been associated with protection against DNA damage, oxidative stress and apoptosis. Moreover, MT may potentially activate certain transcriptional factors by donating zinc. Although MT is a cytosolic protein in resting cells, it can be translocated transiently to the cell nucleus during cell proliferation and differentiation. A number of studies have shown an increased expression of MT in various human tumors of the breast, colon, kidney, liver, lung, nasopharynx, ovary, prostate, salivary gland, testes, thyroid and urinary bladder. However, MT is down-regulated in certain tumors such as hepatocellular carcinoma and liver adenocarcinoma. Hence, the expression of MT is not universal to all human tumors, but may depend on the differentiation status and proliferative index of tumors, along with other tissue factors and gene mutations. In certain tumors such as germ cell carcinoma, the expression of MT is closely related to the tumor grade and proliferative activity. Increased expression of MT has also been observed in less differentiated tumors. Thus, expression of MT may be a potential prognostic marker for certain tumors. There are few reports on the expression of the different isoforms of MT which have been analyzed by specific gene probes. They reveal that certain isoforms are expressed in specific cell types. The factors which can influence MT induction in human tumors are not yet understood. Down-regulation of MT synthesis in hepatic tumors may be related to hypermethylation of the MT-promoter or mutation of other genes such as the p53 tumor suppressor gene. In vitro studies using human cancer cells suggest a possible role for p53 and the estrogen-receptor on the expression and induction of MT in epithelial neoplastic cells. Some of the evidence supporting a role for MT in both intrinsic and acquired drug resistance is critically evaluated in this review. Since chemoresistance in human tumors is a multifactorial phenomenon, it is difficult to conclude that MT is a more crucial factor than others. Therefore, additional experimental data on MT and its isoforms in human tumors, are needed to elucidate the biological functions of MT during tumor progression, along with other tumor markers.

Topics: Drug Resistance, Neoplasm; Humans; Metallothionein; Metals; Neoplasms; Protein Isoforms

Metallothioneins are intracellular macromolecules having a remarkable ability to bind metallic ions. These proteins bind metals indispensable for the organism as well as those which enter the organism incidentally as a result of environmental pollution (e.g. cadmium or lead). The elements which are vital for the organism, and for the homeostasis of which metallothioneins are responsible, are mainly zinc and copper. In the conducted experiments an increase of zinc and metallothioneins content was found in the neoplastic tissue. The increase was perhaps caused by more rigorous demands of the neoplastic cell for zinc and metallothionein imposed by its more dynamic metabolism.

Topics: Humans; Metallothionein; Neoplasms; Zinc

Metallothioneins (Mts) are intracellular proteins whose biological function is zinc and copper regulation as well as detoxification of toxic metals. Another function of these proteins is sweeping away free radicals. MT synthesis induction is stimulated by such factors as metallic ions, free radicals, cytokines, lymphokines and stress. An increased intracellular metallothionein expression was found in many human and animal neoplasms. Copper functions as cofactor in various redox enzymes. At the same time, copper is very toxic to both eukaryotic and prokaryotic cells. Copper ions can bind to proteins and nucleic acids and cause the oxidation of lipids and proteins. The formation of deleterious free radicals is also enhanced by copper ions. For cell viability, regulation of intracellular copper activity is thus crucially important and mechanisms must exist for the homeostasis of copper. An elevated copper level is noted in many types of neoplastic tissue.

Topics: Animals; Copper; Cytokines; Free Radicals; Homeostasis; Humans; Lymphokines; Metallothionein; Neoplasms; Stress, Psychological; Zinc

Evidence concerning a role for metallothionein (MT) in human disease is reviewed. Current knowledge of MT is juxtaposed with our understanding of the pathogenesis of disease. MT is known to modulate three fundamental processes: 1) the release of gaseous mediators such as hydroxyl radical or nitric oxide; 2) apoptosis, and 3) the binding and exchange of heavy metals such as zinc, cadmium or copper. The capability to specifically manipulate MT levels in cells and in mice is beginning to provide answers regarding how MT could impact complex disease scenarios. Associations among MT and several diseases, including cancer, circulatory and septic shock, coronary artery disease, and Alzheimer's disease have been made. Strong evidence exists that MT modulates the immune system. The primary function of MT remains unknown.

Topics: Animals; Apoptosis; Arthritis, Rheumatoid; Cadmium; Copper; Diabetes Mellitus; Free Radicals; HeLa Cells; Humans; Immune System; Metallothionein; Mice; Models, Biological; Neoplasms; Nervous System Diseases; Nitric Oxide; Protein Binding; Shock; Zinc

Matallothioneins are a group of cellular proteins whose synthesis increases considerably in conditions of stressful reactions to harmful environmental factors, especially to heavy metals. They are considered to be proteins of intracellular activity whose specific effect on the metal-dependent enzymes is revealed within the cells, as well as proteins which regulate the transcription process. Metallothioneins released from cells to extracellular fluids, for example due to the damage of membrane, may disclose non-specific effect which usually does not occur. In such conditions, metallothioneins may also affect other cells of tissues and organs placed far away from targets of heavy metal. They also play an important role in the regulation of normal vital functions of the cells in the immune system. In numerous cases, because of their unique chemical structure and biological properties, metallothioneins perform the function of immunomodulators. In the majority of cases, the modulatory effect is favourable for the body as a whole. However, in some cases, this effect is negative, for example it hinders the removal of potentially neoplastic cells from the body.

Topics: Adjuvants, Immunologic; Animals; Heat-Shock Proteins; Humans; Metallothionein; Metals, Heavy; Neoplasms; Transcription, Genetic

Metallothionein(MT) is a group of conjugated proteins which are rich in cysteine with low molecular weight. MTs have recently been proposed to play an important role in carcinogenesis and cancer therapy. The researches included: 1. The possibility of MT in reducing the side effects of anticancer drug. 2. The potential role of MT in carcinogenesis. 3. The correlation between MT and the acquired resistance of tumor cells to anticancer drug.

Topics: Animals; Drug Resistance, Neoplasm; Humans; Metallothionein; Neoplasms

Since its discovery about 40 years ago, there has been a wide interdisciplinary research interest in metallothionein (MT) on its physiological and toxicological aspects. Functionally, MT is involved not only in metal detoxification and homeostasis, but also in scavenging free radicals during oxidative damage. Among over 4500 publications which can be retrieved by Medline search, only about 50 reports have been published on the relationship of MT with ionizing and UV radiation. In this review, we have evaluated critically the published data on the induced synthesis of MT by radiation, and the potential functions of MT in radiation induced cell damage. MT mRNA expression or MT synthesis was found to be induced by exposure of cells in vitro or tissues in vivo to ionizing or UV radiation. In most of the studies in animals and tissue cultures, high doses of ionizing radiation were used to induce MT, and, therefore, it is difficult to extrapolate these results to low level of repeated exposures to radiation in humans. Induced synthesis of MT is considered as one of the mechanisms involved in the adaptive response to low dose radiation exposure. The presence of MT in normal cells may provide protective effects from radiation-induced genotoxicity and cytotoxicity. However, in tumor cells, the presence of MT can result in drug and radiation resistance as well. These effects are modulated by other cellular factors, besides MT, such as antioxidants, and by the cell cycle stages in cell proliferation and differentiation.

Topics: Adaptation, Physiological; Animals; Apoptosis; Humans; Metallothionein; Mice; Mice, Transgenic; Neoplasms; Radiation Protection; Ultraviolet Rays

Metallothioneins (MTs) are major zinc-binding protein thiols that are readily inducible and whose functions remain unclear. Recent evidence supports a role for MT as an antioxidant. Mechanisms underlying this function may include direct interception of free radicals, complexation of redox sensitive transition metals, altered zinc homeostasis or interaction with glutathione (GSH). MT overexpression after direct gene transfer in cultured cells, decreases cytotoxicity, to partially reduce reactive oxygen and nitrogen species and markedly attenuates intracellular oxidation of reporter molecules including dichlorofluorescein and cis-parinaric acid. Conversely, enhanced intracellular oxidation is seen in cells derived from mice lacking both functional MTI and MTII genes. GSH levels are unaffected in MT null cells relative to wildtype, suggesting the antioxidant function of MT is independent of GSH. In tumor cells there is at least a 400-fold range in MT levels and a 10-fold difference in the ratio of nuclear to cytoplasmic distribution. No correlation exists between MT levels and GSH levels demonstrating the autonomous regulation of intracellular thiol pools. This may be important for cancer chemotherapies since MT overexpression is seen in human tumor cells with acquired drug resistance. The authors found no evidence for altered MT isoform profiles in drug resistant cells that overexpress MT. Recent evidence suggests MT subcellular location may dictate functionality and MT may help determine the threshold for apoptosis. Thus, MT is a stress-inducible protein with antioxidant attributes that may participate independently or in conjunction with GSH to protect cells against injurious agents.

Topics: Animals; Antineoplastic Agents; Antioxidants; Apoptosis; Drug Resistance; Gene Expression; Humans; Metallothionein; Mice; Neoplasms; Oxidative Stress

Topics: Antineoplastic Agents; Apoptosis; ATP Binding Cassette Transporter, Subfamily B; DNA Repair; DNA, Neoplasm; Drug Resistance, Neoplasm; Glutathione; Humans; Metallothionein; Neoplasms; Topoisomerase I Inhibitors; Topoisomerase II Inhibitors; Treatment Outcome

Metallothionein is a low-molecular weight protein involved in resistance to toxicity of heavy metals. Recent experimental evidences indicate that metallothionein appears to be a factor in determining the responsiveness of tumor cells to anticancer drugs, such as cisplatin and adriamycin. The resistance of tumor cells having high concentration of metallothionein to cisplatin has been observed in cultured cells and transplanted tumors. On the other hand, increase in metallothionein concentration in normal tissues of tumor-bearing animals prevents side effects of anticancer drugs. Metallothionein may be an important endogenous factor in cancer chemotherapy.

Topics: Animals; Antineoplastic Agents; Drug Resistance, Neoplasm; Humans; Metallothionein; Neoplasms

Topics: Animals; Disease Progression; DNA Methylation; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Metallothionein; Mice; Neoplasms; Point Mutation; Prognosis; Rats; Zinc

Trace elements play important roles and are increasingly recognized as versatile anticarcinogenic agents. Several biologic mechanisms have been proposed to explain how trace elements could reduce the incidence of a number of different cancers. The proposed mechanisms involve the antioxidant potential of trace element dependent enzyme system, induction of metallothionein, effects on immune response and DNA repair system, alterations of carcinogen metabolism, and apoptosis of the initiated cells. However, epidemiologic studies have failed to support the hypothesis that enhanced trace element status reduces the risk of cancer. Furthermore, several animal and in vitro studies have shown carcinogenic potentials of trace elements. A few chemoprevention trials with trace elements have now been conducted.

Topics: Animals; Apoptosis; DNA Repair; Free Radical Scavengers; Humans; Immunocompetence; Metallothionein; Neoplasms; Trace Elements

Metallothioneins are intracellular proteins binding metals. There proteins are involved in zinc and copper homeostasis as well as in organism detoxication of heavy metals. The induction of metallothioneins synthesis is caused not only by metal ions but also by the interleukins, by tumor necrosis factor and by glycocorticoids or the stressing factors. Metallothioneins prove the protective action in cadmium toxication and prevent interaction of cadmium with thiol groups -SH proteins. In neoplasms the increase of metallothionein level occurs both in tumors and in liver, the level of these proteins is correlated with the size of the tumor.

Topics: Animals; Cadmium; Copper; Homeostasis; Humans; Interleukins; Metallothionein; Neoplasms; Tumor Necrosis Factor-alpha; Zinc

Topics: Animals; Biomarkers, Tumor; Drug Resistance, Neoplasm; Gene Expression Regulation; Humans; Metallothionein; Neoplasms

Despite the general lack of clinical evidence supporting the preclinical data, there have been many attempts to overcome cisplatin resistance in clinical situations. These efforts have focused on both the proposed mechanisms of resistance as well as novel approaches to renew efficacy. In this article, the authors summarize the available clinical studies that have intentionally or serendipitously uncovered modulators of cisplatin sensitivity.

Topics: Antineoplastic Combined Chemotherapy Protocols; ATP Binding Cassette Transporter, Subfamily B, Member 1; Biological Transport; Cisplatin; Clinical Trials as Topic; Combined Modality Therapy; DNA Repair; Drug Administration Schedule; Drug Resistance; Drug Resistance, Multiple; Drug Screening Assays, Antitumor; Glutathione; Humans; Immunologic Factors; Metallothionein; Neoplasm Proteins; Neoplasms; Neoplasms, Experimental; Tamoxifen; Topoisomerase I Inhibitors; Topoisomerase II Inhibitors

Topics: Animals; Base Sequence; Cisplatin; DNA Damage; DNA Repair; DNA, Neoplasm; Drug Resistance; Gene Expression Regulation, Neoplastic; Glutathione; Glutathione Transferase; Humans; Metallothionein; Mice; Mice, Inbred C3H; Molecular Sequence Data; Neoplasm Proteins; Neoplasms; Oncogenes; Rats; Signal Transduction; Tumor Cells, Cultured

Topics: Alkylating Agents; Biological Transport; Cell Cycle; DNA Damage; DNA Repair; DNA, Neoplasm; Drug Resistance; Glutathione; Humans; Metallothionein; Neoplasms

Metallothioneins are a group of low-molecular-weight intracellular proteins present in high levels in fetal mammalian livers, bound to zinc and copper. They are also present in two major isoforms in low basal levels in various organs of adults in several species. Although a number of functions have been proposed for metallothioneins, their major biological roles may be in the storage of zinc and copper during rapid growth and development, and also in the detoxification of certain toxic metals. In adult liver, metallothionein is mainly localized in the cytoplasm, it is localized also in the hepatocyte nuclei in human fetal liver and fetal and neonatal rat liver, as determined by immunohistochemical staining with a specific metallothionein antibody. Because of its high expression in fetal development, the potential role of metallothioneins in human tumors was investigated. The cellular localization of metallothionein was demonstrated in various human tumors such as thyroid tumors, testicular germ cell carcinoma, bladder transitional cell carcinomas, and salivary gland tumors. In most of these tumor tissues, metallothioneins were found in high levels in nucleus and cytoplasm in both benign and malignant tumors, although the proliferating edge of the malignant tumors showed most intense metallothionein staining. The expression of metallothionein is not universal to all tumor growth; its presence may depend on various factors, such as the type of tumor, cellular origin, morphological heterogeneity, or stage of growth. Human testicular seminomas, which are well differentiated, showed little expression of metallothionein irrespective of the staging, as compared to less well-differentiated embryonal carcinomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Cell Nucleus; Cytoplasm; Humans; Liver; Metallothionein; Neoplasms

1. Despite considerable progress, cancer continues to remain the number one health threat to human beings. Currently, the targeted antineoplastic therapy is based on an understanding of the molecular mechanisms that govern the normal proliferation and functioning of the cellular elements. Furthermore, the gene-directed therapies and antibody-based approaches are also based on modulating specific signalling processes influencing growth factors and oncogenes that alter cellular proliferation. 2. The intracellular level of metallothionein, a low molecular weight metal binding protein consisting of 25-30% cysteine, containing no aromatic amino acids or disulfide bonds and binding between 5 and 7 g atoms of group II B heavy metals per mole protein, may play an important role in regulating cellular responsiveness to DNA interactive antineoplastic agents. For example, cells with acquired resistance to cisplatin or chlorambucil overexpress metallothionein, which tends to bind these alkylating agents to a higher extent than the non-resistant cells. Since humans synthesize several isoforms of metallothionein. It is not certain which isoforms are increased in cells with acquired resistance to anti-cancer drugs. In addition to sequestering electrophilic anti-cancer drugs, metallothionein, by regulating the activities of zinc-requiring metalloenzymes or scavenging radical species, may alter the therapeutic efficacy of antineoplastic agents.

Topics: Animals; Antineoplastic Agents; Base Sequence; Genetic Therapy; Humans; Metallothionein; Molecular Sequence Data; Neoplasms; Neoplasms, Experimental; Oligonucleotides

Metallothionein (MT) is a low-molecular-weight protein (6800 Da) and one-third of its amino acids are cysteine residues. The 20 cysteines coordinate 7 metal atoms (zinc, copper, and/or cadmium). This protein is extremely inducible by metals as well as a number of organic compounds. MT is though to be an important intracellular storage site for zinc and possibly other essential trace elements. In addition, tolerance to cadmium toxicity is often due to the induction of MT, which sequesters cadmium and lowers its concentration at critical intracellular sites. Recently it has been proposed that MT might play important roles in several aspects of the carcinogenic process. In this context a symposium was held recently on this topic at the 1993 Annual Society of Toxicology Meeting. At this symposium Dr. Cherian discussed the expression of MT in various human tumors and its use as a potential marker of tumor differentiation or cell proliferation. Dr. Imura provided data illustrating that induction of MT can be used as an adjunct in cancer chemotherapy, in preventing toxicity caused by gamma-irradiation or cisplatin (CDDP) and other chemotherapeutics. Induction of MT has been suggested to be an important mechanism of resistance of tumor cells to chemotherapeutic agents, such as CDDP. This is controversial, and various views on this topic were presented by Drs. Howell, Lazo, and Koropatnick. Dr. Waalkes then discussed the role of MT in the carcinogenic and anticarcinogenic effects of metals.

Topics: Animals; Antineoplastic Agents; Cadmium; Carcinogens; Drug Resistance; Humans; Metallothionein; Neoplasm Proteins; Neoplasms

A number of changes have been detected in cisplatin-resistant cells, some of which are likely to be directly involved in the mechanism of resistance. The four most cited mechanisms are reduced accumulation, increased glutathione, increased metallothionein, and enhanced DNA repair. Of these mechanisms, reduced accumulation is probably the most common. Detoxification by glutathione or metallothionein may occur in some circumstances, but the evidence is often ambivalent. Enhanced DNA repair has been observed in several cases, but, to date, few cell lines have been adequately investigated for such changes. These observations demonstrate that multiple mechanisms of resistance exist, and often several may occur in the same cell line. To understand the significance of specific mechanisms, many laboratories are attempting to obtain genetic probes. These probes will then be used to clarify the mechanisms of resistance in fresh clinical samples and hopefully will facilitate improvements in therapeutic response.

Topics: Animals; Cell Death; Cisplatin; Diffusion; DNA Damage; DNA Repair; Drug Resistance; Genes, ras; Glutathione; Humans; Leukemia, Experimental; Metallothionein; Mice; Neoplasm Proteins; Neoplasms; Tumor Cells, Cultured

Topics: Alkylating Agents; Antineoplastic Agents; Cisplatin; Drug Resistance; Gene Expression Regulation, Neoplastic; Humans; Metallothionein; Metals; Neoplasm Proteins; Neoplasms

Topics: Alkylating Agents; Antineoplastic Agents; Cell Hypoxia; Cisplatin; DNA Damage; DNA Repair; Drug Combinations; Drug Interactions; Drug Resistance; Fluorocarbons; Glutathione; Glutathione Transferase; Humans; Hydroxyethyl Starch Derivatives; Indazoles; Metallothionein; Neoplasm Proteins; Neoplasms; Nitroimidazoles; Oxygen; Radiation-Sensitizing Agents; Topoisomerase II Inhibitors; Xanthines

Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Cisplatin; DNA Repair; Doxorubicin; Drug Resistance; Glutathione; Humans; Inactivation, Metabolic; Membrane Glycoproteins; Metallothionein; Neoplasms; Tumor Cells, Cultured

Metallothioneins that bind copper and zinc have an Mr of 6500 daltons, consist of a single polypeptide chain of 61 amino acids, 25-30 percent of whose residues are cysteine, have a metal-binding capacity of between 5 and 7 g atoms/mol, and contain no disulfide bonds or aromatic amino acids. Zincthionein has been postulated to participate in the transport and storage of zinc, which is involved in more than 235 metalloenzymes, including thymidine kinase, RNA polymerase, and ribonuclease, which in turn play crucial roles in the replication and transcription of DNA during cell division. In addition, trace elements including zinc modulate immune response and function. Conversely, zinc deficiency state causes, for example, thymic atrophy and lymphopenia and modifies antibody-mediated responses to both T-cell-dependent and T-cell-independent antigens. The concentrations of copper, zinc, and metallothionein and the copper/zinc ratio are modified in a number of malignancies. For example, the levels of metallothionein in normal and in malignant human livers are 471 and 75 micrograms/g, respectively. In addition, the copper/zinc ratio is significantly increased in human pancreatic cancer from 1.40 to 2.70. Furthermore, studies involving 64Cu in tumor-bearing mice showed that the distribution of 64Cu was altered and that all tumors contained a relatively high level of 64Cu. Moreover, the activity of superoxide dismutase to remove free oxygen radicals is lower in malignant tissues. Finally, the results of clinical studies suggest that the monitoring of the serum copper/zinc ratio may be a valuable tool, not only in determining the extent of malignancies, but also in predicting the efficacy of treatments.

Topics: Animals; Copper; Humans; Metallothionein; Neoplasms; Nutritional Status; Virus Diseases; Zinc

Cadmium is a heavy metal, which is recently known to be hazardous to man. Cadmium workers have been observed to suffer from renal dysfunction and lung emphysema after long-term exposure to cadmium. However, since Itai-Itai disease, osteomalacia provoked in Toyama prefecture of Japan, was designated as a disease caused by cadmium in 1968, much attention has been paid to the health effects of residents in cadmium-polluted areas. The author described here recent progress and perspectives on cadmium health effect studies, cadmium analysis in biological samples; absorption, distribution and excretion of cadmium; health effects of residents in cadmium-polluted area; survey on the health status of Itai-Itai disease patients; beta 2-microglobulinuria; intestinal tract impairment and bone metabolism; effects on bone; effects on the liver; early diagnosis of cadmium effects; effects on future generations; carcinogenicity; critical concentration of cadmium; metallothionein; recommendations for future studies. One-hundred and sixty references are cited in this review.

Topics: Animals; beta 2-Microglobulin; Bone and Bones; Cadmium; Cadmium Poisoning; Haplorhini; Humans; Intestinal Mucosa; Liver; Metallothionein; Mice; Neoplasms; Rabbits; Rats

Mutations in over 100 genes are implicated in autism spectrum disorder (ASD). DNA SNPs, CNVs, and epigenomic modifications also contribute to ASD. Transcriptomics analysis of blood samples may offer clues for pathways dysregulated in ASD. To expand and validate published findings of RNA-sequencing (RNA-seq) studies, we performed RNA-seq of whole blood samples from an Israeli discovery cohort of eight children with ASD compared with nine age- and sex-matched neurotypical children. This revealed 10 genes with differential expression. Using quantitative real-time PCR, we compared RNAs from whole blood samples of 73 Israeli and American children with ASD and 26 matched neurotypical children for the 10 dysregulated genes detected by RNA-seq. This revealed higher expression levels of the pro-inflammatory transcripts

Topics: Antigens, Surface; Autism Spectrum Disorder; Cytokines; Exome Sequencing; Gene Expression Profiling; GPI-Linked Proteins; Humans; Metallothionein; Neoplasms; Sequence Analysis, RNA; Ubiquitins

Metallothionein's (MT) overexpression has been demonstrated immunohistochemically in neoplastic cells of many tumour types. Its elevation above the physiological level has been confirmed in circulation of their hosts. The results of studies dealing with the topic have been summarized to verify if this marker can be applied in the current oncologic practise.. The Pubmed and Google Scholar medical databases were reviewed for full-text articles focused on MT blood (plasma / serum) levels in patients with malignant tumours.. In our review, after a precise selection, we included 8 prospective randomized trials encompassing 561 blood samples taken from patients with a large histopathological spectrum of malignancies. In general, significant differences in blood MT levels between oncological patients and healthy subjects were confirmed. No particular value of the MT level has been demonstrated to be unequivocally predictive of oncologic diseaseCONCLUSION: The results of our review suggest that although the elevation of MT in blood serum in patients with solid malignancy can be regarded as a promising tumour marker, the recommendations of its applicability in clinical practice require to be derived from further research on extended cohorts of patients (Tab. 1, Fig. 1, Ref. 49).

Topics: Biomarkers, Tumor; Humans; Metallothionein; Neoplasms; Prospective Studies; Serum

Metallothioneins (MTs) are important biomarkers for the early diagnosis of heavy metal poisoning and malignancies. Convenient and cost-effective approaches for the rapid detection of MTs are therefore highly desirable for clinical monitoring. Herein, by taking advantage of the enzyme-mimetic activity of nanoparticles and protein corona-based recognition, insufficient polyhedral oligomeric silsesquioxane (POSS) polymer-caged gold nanoparticles (denoted as PP-AuNPs) are developed for the sensitive colorimetric analysis of MTs. In the presence of MTs, the catalytic reduction of yellow 4-nitrophenol to colorless 4-aminophenol is inhibited due to masking of the exposed PP-AuNPs catalytic surface with MTs corona. MTs are quantified by the presented color contrast with a superior sensitivity up to a 1.5 nM detection limit. Most importantly, the heavy metal ion- and aptamer-free PP-AuNPs platform exhibits excellent selectivity toward MTs over various ions, neutral biomolecules, and protein species, and successful applications are demonstrated by the detection of MTs in complex biological samples.

Topics: Catalysis; Colorimetry; Gold; Healthy Volunteers; Humans; Metal Nanoparticles; Metallothionein; Molecular Structure; Neoplasms; Organosilicon Compounds; Protein Corona

The aim of the study was to quantitatively assess the association of metallothionein 2A (. Crude odd ratios (OR) with 95% confidence intervals (CI) were used to estimate associations of the polymorphisms with cancer risk.. Six eligible case-control studies with 1899 cases and 2437 controls focused on rs28366003, and three of those six studies, with 548 cases and 926 controls, additionally focused on rs1610216. Pooled analysis showed that

Topics: Asian People; Case-Control Studies; Genetic Predisposition to Disease; Humans; Metallothionein; Neoplasms; Polymorphism, Single Nucleotide

cis-Diamminedichloroplatinum(ii) (cisplatin), a powerful chemotherapeutic, can incur chemoresistance in cancers, reducing therapeutic success. Metallothioneins (MTs) are suspected of metallodrug interference via ligand removal and metal sequestration. The mechanistic details and reactions rates kobs for the systematic deconstruction of cisplatin by apo-human MT are reported and analysed from mass spectral data.

Topics: Antineoplastic Agents; Apoproteins; Cisplatin; Humans; Kinetics; Metallothionein; Metals; Neoplasms; Platinum; Recombinant Proteins

XIAP-associated factor 1 (XAF1) is a tumor suppressor that is commonly inactivated in multiple human neoplasms. However, the molecular mechanism underlying its proapoptotic function remains largely undefined. Here, we report that XAF1 induction by heavy metals triggers an apoptotic switch of stress response by destabilizing metallothionein 2A (MT2A). XAF1 directly interacts with MT2A and facilitates its lysosomal degradation, resulting in the elevation of the free intercellular zinc level and subsequent activation of p53 and inactivation of XIAP. Intriguingly, XAF1 is activated as a unique transcription target of metal-regulatory transcription factor-1 (MTF-1) in signaling apoptosis, and its protein is destabilized via the lysosomal pathway by MTF-1-induced MT2A under cytostatic stress conditions, indicating the presence of mutual antagonism between XAF1 and MT2A. The antagonistic interplay between XAF1 and MT2A acts as a key molecular switch in MTF-1-mediated cell-fate decisions and also plays an important role in cell response to various apoptotic and survival factors. Wild-type (WT) XAF1 but not MT2A binding-deficient mutant XAF1 increases the free intracellular zinc level and accelerates WT folding of p53 and degradation of XIAP. Consistently, XAF1 evokes a more drastic apoptotic effect in

Topics: Adaptor Proteins, Signal Transducing; Animals; Apoptosis; Apoptosis Regulatory Proteins; Cell Line, Tumor; DNA-Binding Proteins; Gene Expression Regulation, Neoplastic; HCT116 Cells; Humans; Intracellular Signaling Peptides and Proteins; MCF-7 Cells; Metallothionein; Mice; Mice, Nude; Neoplasm Proteins; Neoplasms; RNA Interference; RNA, Small Interfering; Stress, Physiological; Transcription Factor MTF-1; Transcription Factors; Tumor Suppressor Protein p53; X-Linked Inhibitor of Apoptosis Protein; Xenograft Model Antitumor Assays; Zinc

Currently, metallothioneins (MTs) are extensively investigated as the molecular biomarkers and the significant positive association of the MT amount was observed in tumorous versus healthy tissue of various types of malignant tumors, including head and neck cancer. Thus, we proposed a biosensor with fluorescence detection, comprising paramagnetic nanoparticles (nanomaghemite core with gold nanoparticles containing shell) for the magnetic separation of MT, based on affinity of its sulfhydryl groups toward gold. Biosensor was crafted from PDMS combined with technology of 3D printing and contained reservoir with volume of 50 μL linked to input (sample/detection components and washing/immunobuffer) and output (waste). For the immunolabeling of immobilized MT anti-MT antibodies conjugated to CdTe quantum dots through synthetic heptapeptide were employed. After optimization of fundamental conditions of the immunolabeling (120 min, 20°C, and 1250 rpm) we performed it on a surface of paramagnetic nanoparticles in the biosensor reservoir, with evaluation of fluorescence of quantum dots (λexc 400 nm, and λem 555 nm). The developed biosensor was applied for quantification of MT in cell lines derived from spinocellular carcinoma (cell line 122P-N) and fibroblasts (122P-F) and levels of the biomarker were found to be about 90 nM in tumor cells and 37 nM in fibroblasts. The proposed system is able to work with low volumes (< 100 μL), with low acquisition costs and high portability.

Topics: Biosensing Techniques; Cadmium Compounds; Cell Line, Tumor; Dimethylpolysiloxanes; Fluorescence; Gold; Humans; Magnetics; Metal Nanoparticles; Metallothionein; Neoplasms; Printing, Three-Dimensional; Quantum Dots; Tellurium

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

Topics: Algorithms; Blotting, Western; Child; Humans; Metallothionein; Neoplasms; Zinc

Metallothioneins (MT) are low molecular weight, cysteine-rich proteins maintaining metal ions homeostasis. They play a role in carcinogenesis and may also cause chemoresistance. The aim of the study was to explore the importance of MT serum levels in children suffering from malignant tumours. This prospective study involves examination of 865 samples from 172 patients with malignant tumours treated from 2008 to 2011 at University Hospital Motol. MT serum levels were determined using differential pulse voltammetry-Brdicka reaction. Mean MT level was 2.7 ± 0.5 μM. There was no statistically significant difference between MT levels in different tumours. We also did not find any correlation between MT levels and response to therapy or clinical stages. However, we found a positive correlation between MT levels and age (p = 0.009) and a negative correlation with absolute lymphocyte number (p = 0.001). The fact that patients who had early disease recurrence had lower MT levels during the treatment (complete remission 2.67 vs. recurring 2.34, p = 0.001) seems to be important for clinical practice. Accordingly we believe that there is benefit in further studies of serum MT levels in tumours.

Topics: Adolescent; Biomarkers, Tumor; Child; Child, Preschool; Disease Progression; Female; Humans; Infant; Male; Metallothionein; Neoplasms; Prognosis

Topics: Diagnostic Techniques and Procedures; Electrochemical Techniques; History, 20th Century; Humans; Metallothionein; Neoplasms; Peptide Mapping

Tumour markers are substances produced by malignant cells or by the organism as a response to cancer development. Determination of their levels can, therefore, be used to monitor the risk, presence and prognosis of a cancer disease or to monitor the therapeutic response or early detection of residual disease. Time-consuming imaging methods, examination of cerebrospinal fluid or tumour tissue and assays for hormones and tumour markers have been used for cancer diagnosis. However, no specific marker for diagnosis of childhood solid tumours has been discovered yet. In this study, metallothionein (MT) was evaluated as a prospective marker for such diseases. Serum metallothionein levels of patients with childhood solid tumours were determined using differential pulse voltammetry - Brdicka reaction. A more than 5-fold increase in the amount of metallothionein was found in sera of patients suffering from cancer disease, compared with those in sera of healthy donors. The average metallothionein level in the sera of healthy volunteers was 0.5 ± 0.2 μmol · dm⁻³ and was significantly different (p<0.05, determined using the Schefe test) from the average MT level found in serum samples of patients suffering from childhood solid tumours (3.4 ± 0.8 μmol · dm⁻³). Results found in this work indicate that the MT level in blood serum can be considered as a promising marker for diagnostics, prognosis and estimation of therapy efficiency of childhood tumours.

Topics: Biomarkers, Tumor; Blotting, Western; Child; Electrochemistry; Humans; Medulloblastoma; Metallothionein; Neoplasms; Neuroblastoma; Osteosarcoma; Risk Factors; Sarcoma, Ewing

Acquiring the immune-mediated apoptosis and the ability to regulate the cytotoxic immune response are the main phenomena playing fundamental roles in such situations as neoplasm survival and creation of immune tolerance during pregnancy. The aim of this study was to investigate these phenomena through the evaluation of metallothionein and RCAS1 proteins in neoplasm and its healthy environment (clear surgical margin), physiological conditions in placenta and its environment (decidua) and the comparison to non-neoplasmatic lesions originating from the environment (nasal polyps, endometriosis). We have shown that the growth of RCAS1 expression was simultaneous to the infiltration of activated immunological cells of tumor environment as well as decidua. The activity of immunological cells was in our study selectively suppressed. Metallothionein expression growth was also observed in healthy tumors stroma and in decidua probably in response to the growing cytotoxic activity and tumor spread. Alterations in RCAS1 and Metallothionein expression seem to be associated with local immune dysfunction in nasal polyps and endometriosis. In conclusion, the ability to compensate the growing cytotoxic immune response is physiologically observed in decidua, the lost of this ability in tumor environment might participate in the development of tumor spread.

Topics: Antigens, Neoplasm; Apoptosis; Decidua; Endometriosis; Female; Humans; Immune Tolerance; Immunity, Cellular; Lymphatic Metastasis; Menstrual Cycle; Metallothionein; Nasal Polyps; Neoplasms; Placenta

We tested the hypothesis that the effects on gene expression of altered DNA methylation by 5-aza-2'-deoxycytidine (5-aza-CdR) and genetic (DNMT knockout) manipulation of DNA are similar, and distinct from Trichostatin A (TSA)-induced chromatin decondensation. Surprisingly, the effects of 5-aza-CdR were more similar to those of TSA than to DNMT1, DNMT3B, or double DNMT somatic cell knockout. Furthermore, the effects of 5-aza-CdR were similar at one and five days exposure, suggesting active demethylation or direct influence of both drugs on the stability of methylation and/or chromatin marks. Agents that induce gene activation through hypomethylation may have unintended consequences, since nearly as many genes were downregulated as upregulated after demethylation. In addition, a 75 kb cluster of metallothionein genes was coordinately regulated.

Topics: Algorithms; Apoptosis; Azacitidine; Cell Division; Cell Line, Tumor; Cluster Analysis; Decitabine; DNA (Cytosine-5-)-Methyltransferase 1; DNA (Cytosine-5-)-Methyltransferases; DNA Methylation; DNA Methyltransferase 3B; Epigenesis, Genetic; Gene Expression Regulation, Neoplastic; Gene Silencing; Genome; Humans; Hydroxamic Acids; Metallothionein; Methyltransferases; Neoplasms; Oligonucleotide Array Sequence Analysis; Promoter Regions, Genetic; Reproducibility of Results; RNA, Messenger; Transcriptional Activation

The metallothionein (MT)3 gene is expressed predominantly in the brain and the organs of the reproductive system, and fails to respond to metal ions in vivo. A CTG repeat was proposed to function as a potential repressor element in nonpermissive cells, and a sequence similar to the JC virus silencer element was found to function as a negative element in permissive primary astrocytes. The objective of this study was to characterize further the mechanisms governing cell-type specific MT-3 gene transcription. We searched for a suitable cell line expressing the MT-3 gene to be used for determination of MT-3 promoter tissue specificity, and showed that MT-3 expression is activated during neuroectodermal differentiation of P19 cells induced by retinoic acid to levels similar to those found in whole brain. Deletion of the CTG repeat or of the JC virus silencer did not promote MT-3 promoter activity in nonpermissive cells, or enhance expression in permissive cells. We identified MT-3 promoter sequences interacting with liver and brain nuclear proteins, as assayed by DNase I footprinting analyses and electrophoretic mobility shift assay, and assessed the role of these sequences in the regulation of MT-3 expression by cotransfection experiments. We generated stable transfectants in permissive C6 and nonpermissive NIH-3T3 cells, and analysed the methylation status of the MT-3 gene. These studies show that regulation of tissue-specific MT-3 gene expression does not appear to involve a repressor, and suggest that other mechanisms such as chromatin organization and epigenetic modifications could account for the absence of MT-3 gene transcription in nonpermissive cells.

Topics: 3T3 Cells; Animals; Base Sequence; Cell Differentiation; Cells, Cultured; Chlorocebus aethiops; COS Cells; DNA; Gene Expression Regulation, Neoplastic; Humans; Metallothionein; Metallothionein 3; Mice; Molecular Sequence Data; Mutagenesis, Site-Directed; Neoplasms; Neoplasms, Experimental; Neuroglia; Neurons; Promoter Regions, Genetic; Rats; Rats, Sprague-Dawley; Recombinant Fusion Proteins; RNA, Messenger; RNA, Neoplasm; Species Specificity; Teratocarcinoma; Transcriptional Activation; Transfection; Tretinoin; Tumor Cells, Cultured

Topics: Animals; Cell Division; Cell Survival; Genetic Therapy; Genetic Vectors; Glial Fibrillary Acidic Protein; Humans; Hygromycin B; Insulin-Like Growth Factor I; Metallothionein; Mice; Neoplasms; Plasmids; RNA, Antisense; Transfection; Tumor Cells, Cultured

Metallothioneins (MTs) are major thiol-containing intracellular proteins that bind metals, are induced by stress, and have been implicated in resistance to drugs and heavy metals.. To examine the hypothesis that the protective functionality of MT may be dictated by its subcellular localization.. We analyzed the basal MT content in 53 adherent cell lines of the National Cancer Institute (NCI) tumor panel and quantified the nuclear/cytoplasmic distribution of MT using confocal laser scanning microscopy and a recently described immunofluorescence-based algorithm.. Among these cell types we found a 400-fold range in the basal MT levels and a tenfold range in the ratio of the nuclear to cytoplasmic MT immunostaining that was independent of basal MT content. Total MT levels and nuclear/cytoplasmic distribution were independent of total glutathione content, suggesting autonomous regulation of these protective protein and nonprotein thiol pools. Approximately 50% (29/53) of the cell lines had a greater nuclear than cytoplasmic MT density and were defined as having a karyophilic phenotype. Tissue specificity of MT localization was seen with breast cancer cell lines, which were cytoplasmophilic, whereas prostate-derived cells were karyophilic. Among the 25000 unrestricted compounds in the NCI database, we detected a correlation between total basal MT levels and resistance to CdCl2, four Pt- and two Cu-containing compounds. High nuclear/cytoplasmic MT values correlated with resistance to six Cu-, six Pb-, and one Zn-containing compounds.. These results demonstrated significant diversity in MT content and subcellular localization in human tumor cells. Moreover, both basal MT levels and subcellular distribution appeared to be determinants of cellular responsiveness to metal-containing compounds.

Topics: Cytoplasm; Drug Resistance; Drug Screening Assays, Antitumor; Fluorescent Antibody Technique; Glutathione; Humans; Metallothionein; Metals, Heavy; Neoplasms; Tumor Cells, Cultured

Sera of patients with various inflammatory and autoimmune rheumatic diseases were screened for the presence of xanthine oxidase (XOD) and compared to sera from healthy donors and patients with nonrheumatic diseases including AIDS, internal diseases, and different carcinomas. Up to 50-fold higher levels of XOD were detected in rheumatic sera (P < 0.001). In addition, serum sulfhydryls (SH) were determined as sensitive markers of oxidative stress. The SH status in rheumatic patients was diminished by 45-75% (P < 0.001) and inversely correlated to the concentration of serum XOD (R = 0.73), suggesting a causal interrelation. The depletion of serum sulfhydryls by the oxyradical-producing XOD/acetaldehyde system was mimicked successfully ex vivo in human serum from healthy donors. Cortisone treatment of patients suffering from systemic lupus erythematosus and rheumatoid arthritis impressively normalized elevated XOD concentrations in rheumatic sera to those of healthy controls. The participation of xanthine oxidase in the depletion of serum antioxidants in rheumatic patients is discussed in the light of substrate availability and Km values.

Topics: Acetaldehyde; Acquired Immunodeficiency Syndrome; Autoimmune Diseases; Biomarkers; Cohort Studies; Cortisone; Female; Humans; Inflammation; Internal Medicine; Male; Metallothionein; Neoplasms; Organometallic Compounds; Oxidation-Reduction; Oxygen; Rheumatic Diseases; Schiff Bases; Singlet Oxygen; Stress, Physiological; Sulfhydryl Compounds; Xanthine Oxidase

Gel-filtered sera of patients with various inflammatory and autoimmune rheumatic diseases (N = 354) were screened for the presence of the inflammation marker Cu-thionein. The concentrations of Cu-thionein were significantly diminished in patients with connective tissue diseases (P < 0.001). Sera of patients suffering from inflammatory rheumatic diseases were almost totally depleted of this low-molecular-weight copper protein that exerts pronounced superoxide dismutase activity and scavenges effectively hydroxyl radicals and singlet oxygen. Cortisone treatment of patients with rheumatoid arthritis, systemic lupus erythematosus, and polymyalgia rheumatica replenished impressively the serum concentration of Cu-thionein. The partial oxidation of the EPR-silent Cu(I)-chromophore to Cu(II)/Cu(I)-thionein, which is essential for the catalytic dismutation of superoxide, was monitored by electron paramagnetic resonance in the presence of activated neutrophils and monocytes. Release of Cu-thionein during the oxidative burst of peripheral blood monocytes was demonstrated in vitro. The role of prooxidant-antioxidant imbalances in the pathogenesis of rheumatic diseases is discussed.

Topics: Acquired Immunodeficiency Syndrome; Autoimmune Diseases; Chromatography, Gel; Connective Tissue Diseases; Copper; Cortisone; Humans; Inflammation; Internal Medicine; Metallothionein; Neoplasms; Oxidation-Reduction; Phagocytes; Rheumatic Diseases

Topics: Antineoplastic Agents; Cadmium; Drug Resistance; Metallothionein; National Institutes of Health (U.S.); Neoplasms; United States; Zinc

Twelve Patients with malignant neoplasms were treated in twenty-five courses with high-dose Cisplatin and high-dose Bismuth Subnitrate. The pharmacokinetics of Bismuth Subnitrate and Cisplatin were studied in several courses. Bismuth Subnitrate was administered orally at a dose of 150 mg/kg/day for 10 days, and an average dose of 108 mg/m2 of cisplatin was administered intravenously on the 6th day after Bismuth Subnitrate administration. The concentration of Bismuth in blood and urine showed a similar increase, reaching a plateau 5 days after, and peaking 12 days after starting administration. It is estimated that 10-day administration of high-dose Bismuth Subnitrate was appropriate to maintain an adequate concentration of Bismuth for preinduction of Metallothionein in organs. The pharmacokinetics of cisplatin in plasma indicated as follows. a) In terms of the nephrotoxic factors, the Cmax of platinum did not increase dose-dependently, and total clearance of platinum was constant under the same time of injection; b) As for the antitumor effect, AUC of ultrafilterable (free) platinum increased dose-dependently. From the standpoint of pharmacology, high-dose Bismuth Subnitrate was believed to reduce the nephrotoxicity of cisplatin without reducing its antitumor effect.

Topics: Administration, Oral; Antacids; Bismuth; Cisplatin; Humans; Injections, Intravenous; Metallothionein; Neoplasms

As an alternative to directing plant or bacterial toxins to surface receptors, we are investigating the possibility of killing tumor cells by the expression of an exogenously introduced toxin gene (i.e., cell suicide). Tissue-specific gene regulatory elements might thus be exploited to achieve selective killing. To assess the feasibility of such an approach, we have transfected human cells (HeLa, B-lymphoblastoid, and 293 cells) with plasmids containing the diphtheria toxin A-chain (DT-A) coding sequence. The presence of the DT-A sequence lowered the level of transient expression of chloramphenicol acetyltransferase from a cotransfected plasmid, pSV2cat. This expression level in B-cells was further diminished by the inclusion of an immunoglobulin enhancer in the DT-A plasmid. In cotransfection experiments with a DT-A plasmid lacking an enhancer, chloramphenicol acetyltransferase expression was much more strongly inhibited in 293 cells (which express adenovirus E1A and E1B products) than in the other cell types; furthermore, the presence of the DT-A sequence eliminated recovery of G418-resistant 293 cell transformants after transfection with a plasmid containing the neo selectable marker. These results suggest that cell-specific regulatory mechanisms can be exploited to achieve selective cell killing by expression of an introduced toxin gene.

Topics: Acetyltransferases; Chloramphenicol O-Acetyltransferase; Diphtheria Toxin; Enhancer Elements, Genetic; Gene Expression Regulation; Humans; Metallothionein; Neoplasms; Plasmids; Promoter Regions, Genetic; Transcription, Genetic; Transfection

Subpopulations of human tumor-derived cell lines A101D, A204, and A549 were screened for Cd2+ cytotoxic response. Three of six A549, two of seven A101D, and four of seven A204 subpopulations were found to differ significantly from the parental line. A variant subpopulation of A101D (T3) was shown by flow cytometry to be comprised of cells having two distinct DNA histograms. One histogram, type 1, resembles that of normal human fibroblasts. The other, type 2, represents cells with one-third more DNA. Early passage T3 clonal populations were comprised primarily of type 1 cells. With passage, type 1 cells decreased relative to type 2 so that by passage 47 the culture was predominantly type 2. Correspondingly, the A101D T3 subpopulation became more Cd2+ sensitive with time in culture. Subclones having only type 1 DNA histograms were found to be Cd2+ resistant relative to subclones with type 2 histograms, and treatment of A101D T3 cultures having approximately equal amounts of type 1 and 2 cells with 2 microM Cd2+ resulted in the selection of type 1 cells. The enhanced Cd2+ resistance phenotype shown by A101D T3 type 1 cells correlated with reduced Cd2+ uptake and is not attributable to enhanced metallothionein synthesis.

Topics: Analysis of Variance; Antineoplastic Agents; Cadmium; Cell Line; Clone Cells; DNA, Neoplasm; Drug Resistance; Genetic Variation; Humans; Metallothionein; Neoplasms

Topics: Angiogenesis Inducing Agents; Animals; Ceruloplasmin; Copper; Hepatolenticular Degeneration; Humans; Menkes Kinky Hair Syndrome; Metallothionein; Mice; Neoplasms; Neovascularization, Pathologic