Serum copper and zinc levels and copper/zinc ratio in patients with breast cancer

Cuproptosis in cancer: biological implications and therapeutic opportunities

Cuproptosis, a newly identified copper (Cu)-dependent form of cell death, stands out due to its distinct mechanism that sets it apart from other known cell death pathways. The molecular underpinnings of cuproptosis involve the binding of Cu to lipoylated enzymes in the tricarboxylic acid cycle. This interaction triggers enzyme aggregation and proteotoxic stress, culminating in cell death. The specific mechanism of cuproptosis has yet to be fully elucidated. This newly recognized form of cell death has sparked numerous investigations into its role in tumorigenesis and cancer therapy. In this review, we summarized the current knowledge on Cu metabolism and its link to cancer. Furthermore, we delineated the molecular mechanisms of cuproptosis and summarized the roles of cuproptosis-related genes in cancer. Finally, we offered a comprehensive discussion of the most recent advancements in Cu ionophores and nanoparticle delivery systems that utilize cuproptosis as a cutting-edge strategy for cancer treatment.

Activate the endogenous Cu2+ switch for Zn(DDC)2 liposomes conversion: Providing a safer and less toxic alternative in cancer therapy

The ancient anti-alcohol drug disulfiram (DSF) has gained widespread attention for its highly effective anti-tumor effects in cancer treatment. Our previous studies have developed liposome of Cu (DDC)2 to overcome the limitations, like the poor water solubility. However, Cu (DDC)2 liposomes still have shown difficulties in severe hemolytic reactions at high doses and systemic toxicity, which have limited their clinical use. Therefore, this study aims to exploratively investigate the feasibility of using DSF or DDC in combination also can chelate Zn2+ to form zinc diethyldithiocarbamate (Zn (DDC)2). Furthermore, this study prepared stable and homogeneous Zn (DDC)2 liposomes, which were able to be released in the tumor microenvironment (TME). The released Zn (DDC)2 was converted to Cu (DDC)2 with the help of endogenous Cu2+-switch enriched in the TME, which has a higher stability constant compared with Zn (DDC)2. In other words, the Cu2+-switch is activated at the tumor site, completing the conversion of the less cytotoxic Zn (DDC)2 to the more cytotoxic Cu (DDC)2 for effective tumor therapy so that the Zn (DDC)2 liposomes in vivo achieved the comparable therapeutic efficacy and provided a safer alternative to Cu (DDC)2 liposomes in cancer therapy.

Cuproptosis-related risk score predicts prognosis and characterizes the tumor microenvironment in colon adenocarcinoma

Introduction

Cuproptosis is a novel copper-dependent regulatory cell death (RCD), which is closely related to the occurrence and development of multiple cancers. However, the potential role of cuproptosis-related genes (CRGs) in the tumor microenvironment (TME) of colon adenocarcinoma (COAD) remains unclear.

Methods

Transcriptome, somatic mutation, somatic copy number alteration and the corresponding clinicopathological data of COAD were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus database (GEO). Difference, survival and correlation analyses were conducted to evaluate the characteristics of CRGs in COAD patients. Consensus unsupervised clustering analysis of CRGs expression profile was used to classify patients into different cuproptosis molecular and gene subtypes. TME characteristics of different molecular subtypes were investigated by using Gene set variation analysis (GSVA) and single sample gene set enrichment analysis (ssGSEA). Next, CRG Risk scoring system was constructed by applying logistic least absolute shrinkage and selection operator (LASSO) cox regression analysis and multivariate cox analysis. Real-time quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry (IHC) were used to exam the expression of key Risk scoring genes.

Results

Our study indicated that CRGs had relatively common genetic and transcriptional variations in COAD tissues. We identified three cuproptosis molecular subtypes and three gene subtypes based on CRGs expression profile and prognostic differentially expressed genes (DEGs) expression profile, and found that changes in multilayer CRGs were closely related to the clinical characteristics, overall survival (OS), different signaling pathways, and immune cell infiltration of TME. CRG Risk scoring system was constructed according to the expression of 7 key cuproptosis-related risk genes (GLS, NOX1, HOXC6, TNNT1, GLS, HOXC6 and PLA2G12B). RT-qPCR and IHC indicated that the expression of GLS, NOX1, HOXC6, TNNT1 and PLA2G12B were up-regulated in tumor tissues, compared with those in normal tissues, and all of GLS, HOXC6, NOX1 and PLA2G12B were closely related with patient survival. In addition, high CRG risk scores were significantly associated with high microsatellite instability (MSI-H), tumor mutation burden (TMB), cancer stem cell (CSC) indices, stromal and immune scores in TME, drug susceptibility, as well as patient survival. Finally, a highly accurate nomogram was constructed to promote the clinical application of the CRG Risk scoring system.

Discussion

Our comprehensive analysis showed that CRGs were greatly associated with TME, clinicopathological characteristics, and prognosis of patient with COAD. These findings may promote our understanding of CRGs in COAD, providing new insights for physicians to predict prognosis and develop more precise and individualized therapy strategies.

LncRNAs and regulated cell death in tumor cells

Regulated Cell Death (RCD) is a mode of cell death that occurs through drug or genetic intervention. The regulation of RCDs is one of the significant reasons for the long survival time of tumor cells and poor prognosis of patients. Long non-coding RNAs (lncRNAs) which are involved in the regulation of tumor biological processes, including RCDs occurring on tumor cells, are closely related to tumor progression. In this review, we describe the mechanisms of eight different RCDs which contain apoptosis, necroptosis, pyroptosis, NETosis, entosis, ferroptosis, autosis and cuproptosis. Meanwhile, their respective roles in the tumor are aggregated. In addition, we outline the literature that is related to the regulatory relationships between lncRNAs and RCDs in tumor cells, which is expected to provide new ideas for tumor diagnosis and treatment.

Biomimetic Approach to Promote Cellular Uptake and Enhance Photoacoustic Properties of Tumor-Seeking Dyes

The attachment of glucose to drugs and imaging agents enables cancer cell targeting via interactions with GLUT1 overexpressed on the cell surface. While an added benefit of this modification is the solubilizing effect of carbohydrates, in the context of imaging agents, aqueous solubility does not guarantee decreased π-stacking or aggregation. The resulting broadening of the absorbance spectrum is a detriment to photoacoustic (PA) imaging since the signal intensity, accuracy, and image quality all rely on reliable spectral unmixing. To address this major limitation and further enhance the tumor-targeting ability of imaging agents, we have taken a biomimetic approach to design a multivalent glucose moiety (mvGlu). We showcase the utility of this new group by developing aza-BODIPY-based contrast agents boasting a significant PA signal enhancement greater than 11-fold after spectral unmixing. Moreover, when applied to targeting cancer cells, effective staining could be achieved with ultra-low dye concentrations (50 nM) and compared to a non-targeted analogue, the signal intensity was >1000-fold higher. Lastly, we employed the mvGlu technology to develop a logic-gated acoustogenic probe to detect intratumoral copper (i.e., Cu(I)), which is an emerging cancer biomarker, in a murine model of breast cancer. This exciting application was not possible using other acoustogenic probes previously developed for copper sensing.

Study of Serum Zinc and Copper Levels and Tumor Pathology: A Pilot Study in People Affected with Head and Neck Cancers

This study aimed to determine understanding the role of serum copper, zinc and copper/zinc ratio with tumor staging in people newly diagnosed to be affected with Head and Neck cancer and by comparing with age matched health individuals devoid of any orodental maladies. The study included patients confirmed to be affected with HN cancer with histological diagnosis of Head and Neck cancer (60) and age matched healthy volunteers (N = 23). The demographic details like age, domicile, menopausal status and pathological details (like tumor stage, number of lymph node involvement, tumor size) were collected from the patient's hospital data file. The serum levels of zinc and copper assayed as per standard procedures and the zinc/copper was calculated for the cancer patients and controls. The data were subjected to unpaired "t" test and ANOVA with Bonferroni's multiple comparisons. The association between zinc and copper levels with pathological details between the variables was ascertained using the Pearson correlation coefficient(r). A statistical value of p < 0.05 was considered to be significant in agreeance to the accepted norms. Results: This result of the study indicates that when compared to the healthy individuals, the serum levels of copper, and zinc, and copper/zinc ratio were high in patients with H&N cancer. Also when compared with controls, the levels of zinc decreased, while that of copper and copper/zinc ratio increased in people affected with H&N cancer (p = 0.017 to 0.0001) and with the stage of the tumor (p = 0.03 to 0.001). The results of the study suggest that levels of serum zinc were significantly lower and that of copper higher in H&N cancer patients than that in controls and also that it was dependent on the tumor stage. When analyzed cumulatively the results hint that zinc and copper, due to their role in free radical generation and prevention have an important role in cancer progression and possible prevention by judicious intervention.

Cuproptosis-Related LncRNA Signature for Predicting Prognosis of Hepatocellular Carcinoma: A Comprehensive Analysis

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide and has a poor prognosis. Cuproptosis is a novel mode of cell death that has only recently been discovered. Considering the critical role of lncRNAs in liver cancer development, the aim of this study was to construct a prognostic signature based on cuproptosis-related lncRNAs (CRlncRNAs). We downloaded RNA-sequencing data and corresponding clinical information of patients with HCC from The Cancer Genome Atlas (TCGA) database. To verify the robustness of the model, we added an external validation set obtained from the Gene Expression Omnibus (GEO): GSE40144. In addition, we identified the cuproptosis-related genes (CRGs) based on previous reports. Pearson correlation analysis, univariate Cox regression, and least absolute shrinkage and selection operator (LASSO) Cox regression analysis were utilized to screen for genes associated with prognosis. On this basis, multivariate Cox regression and stepAIC were used to further construct and optimize the prognostic model. The simplified signature with the lowest Akaike information criterion (AIC) value was considered the prognostic signature. Seven different algorithms were used to perform immune infiltration analysis. The single-sample Gene Set Enrichment Analysis (ssGSEA) algorithm was utilized to find the difference in immune function between the high- and low-risk groups. Finally, in vitro experiments were performed by quantitative real-time PCR (qRT-PCR) analysis using HCC cell lines to validate the expression of prognostic genes. We identified 3 lncRNAs (CYTOR, LINC00205, and LINC01184) as independent risk factors for HCC. The receiver operating characteristic (ROC) curves calculated that the AUC at 1, 3, and 5 years reached 0.717, 0.633, and 0.607, respectively. The expression levels of 41 immune checkpoints differed significantly between the high- and low-risk groups, and there were significant differences in sensitivity to immunotherapy between the high- and low-risk groups. The risk model could also serve as a promising predictor of immunotherapeutic response, which has been verified by the TIDE algorithm (p < 0.001). Overall, we propose a signature related to CRlncRNAs that can be used to predict the prognosis of HCC patients, which was validated in external cohort and in vitro experiments.

Relationships Between Biological Heavy Metals and Breast Cancer: A Systematic Review and Meta-Analysis

Introduction

Heavy metals were classified as essential, probably essential, and potentially toxic in the general population. Until now, it has been reported inconsistently on the association between heavy metals and BC. In this meta-analysis, we aimed to assess the association between heavy metals and BC and review the potential mechanisms systematically.

Methods

We searched for epidemiological studies in English about the association between heavy metals and BC published before September 2020 in PubMed, Web of Science, and Embase databases. In total 36 studies, comprising 4,151 individuals from five continents around the world were identified and included.

Results

In all biological specimens, Cu, Cd, and Pb concentrations were higher, but Zn and Mn concentrations were lower in patients with BC than in non-BC participants [SMD (95% CIs): 0.62 (0.12, 1.12); 1.64 (0.76, 2.52); 2.03 (0.11, 3.95); −1.40 (−1.96, −0.85); −2.26 (−3.39, −1.13); p = 0.01, 0.0003, 0.04, <0.0001, <0.0001]. Specifically, higher plasma or serum Cu and Cd, as well as lower Zn and Mn, were found in cases [SMD (95% CIs): 0.98 (0.36, 1.60); 2.55 (1.16, 3.94); −1.53 (−2.28, −0.78); −2.40 (−3.69, −1.10); p = 0.002, 0.0003, <0.0001, 0.0003]; in hair, only lower Zn was observed [SMD (95% CIs): −2.12 (−3.55, −0.68); p = 0.0004]. Furthermore, the status of trace elements probably needs to be re-explored, particularly in BC. More prospective studies, randomized clinical trials, and specific pathogenic studies are needed to prevent BC. The main mechanisms underlying above-mentioned findings are comprehensively reviewed.

Conclusion

For BC, this review identified the current knowledge gaps which we currently have in understanding the impact of different heavy metals on BC.

Systematic Review Registration

www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020176934, identifier: CRD42020176934.

Prediagnostic Levels of Copper and Zinc and Breast Cancer Risk in the ORDET Cohort

BACKGROUND

Case-control studies show that copper (Cu) is high and zinc (Zn) low in blood and urine of women with breast cancer compared with controls.

METHODS

To assess whether prediagnostic Cu and Zn are associated with breast cancer risk, OR of breast cancer according to Cu, Zn, and Cu/Zn ratio in plasma and urine was estimated in a nested case-control study within the ORDET cohort, using conditional logistic regression adjusted for multiple variables: First 496 breast cancer cases and matched controls, diagnosed ≥2 years after recruitment (to eliminate reverse causation) were analyzed. Then all eligible cases/controls were analyzed with stratification into years from recruitment to diagnosis.

RESULTS

For women diagnosed ≥2 years, compared with lowest tertiles, breast cancer risk was higher in the highest tertile of plasma Cu/Zn ratio (OR, 1.75; 95% CI, 1.21-2.54) and the highest tertile of both plasma and urine Cu/Zn ratio (OR, 2.37; 95% CI, 1.32-4.25). Risk did not vary with ER/PR/HER2 status. For women diagnosed <2 years, high Cu/Zn ratio was strongly associated with breast cancer risk.

CONCLUSIONS

Our prospective findings suggest that increased Cu/Zn ratio in plasma and urine may be both an early marker of, and a risk factor for, breast cancer development. Further studies are justified to confirm or otherwise our results and to investigate mechanisms.

IMPACT

Our finding that prediagnostic Cu/Zn ratio is a strong risk factor for breast cancer development deserves further investigation and, if confirmed, might open the way to interventions to reduce breast cancer risk in women with disrupted Cu/Zn homeostasis.

Comparison of the Index of Nutritional Quality in Breast Cancer Patients With Healthy Women

Background

The index of nutritional quality (INQ) is derived from the food frequency questionnaire (FFQ) and is a method of quantitative and qualitative analysis of diet. This study aimed to compare the INQ for different dietary components between breast cancer (BC) patients and healthy control.

Methods

This case-control study was performed on 180 women with BC and 360 healthy women. Data on general characteristics, medical history, anthropometric indices, physical activity, alcohol consumption, reproductive history, smoking, and dietary intake were collected. A valid FFQ was used to assess the intake of nutrients and the INQ was calculated based on the daily intake of the nutrients.

Results

There was a significant association between BC and INQ of vitamin A (OR = 0.07, 0.01-0.29), vitamin E (OR = 0.43, 0.20-0.93), vitamin B6 (OR = 0.003, 0.000-0.021), riboflavin (OR = 0.25, 0.11-0.59), vitamin K (OR = 0.58, 0.37-0.90), biotin (OR = 0.07, 0.02-0.26), vitamin B12 (OR = 0.32, 0.18-0.56), vitamin C (OR = 0.72, 0.55-0.95), zinc (OR = 0.020, 0.005-0.083), calcium (OR = 0.14, 0.04-0.54) and magnesium (OR = 0.003, 0.000-0.024). Further adjustment for BMI disappeared the association between INQ of vitamin C and BC. The results did not change after further adjustments for waist circumstance and total calorie intake.

Conclusion

A significant association was observed between BC and the INQ of vitamin A, vitamin E, vitamin B6, riboflavin, vitamin K, biotin, vitamin B12, vitamin C, zinc, calcium, and magnesium. The INQ can be used as an indicator in assessing clinical nutrition-related problems. Future longitudinal studies are needed to confirm these results.

Zinc Transporter 9 (SLC30A9) Expression Is Decreased in the Vaginal Tissues of Menopausal Women

Our aim was to compare zinc transporter (ZnT/SLC30A, and ZIP/SLC39A) expression between pre- and postmenopausal women in human vaginal tissues. Zinc transporter families are responsible for the maintenance of intracellular zinc concentrations. Zinc has significant effects on the extracellular matrix composition. Vaginal wall biopsies were obtained from seven premenopausal and seven postmenopausal women. mRNA expression of twenty-four zinc transporters was determined by quantitative real-time PCR. Zinc transporter expression at the protein level was assessed by immunohistochemistry. Student's t test and Mann-Whitney U test were used to compare data. ZnT4 and ZnT9 mRNA expression were significantly lower in postmenopausal women compared with premenopausal women (mean ± SD mRNA expression in relative units, 96.43 ± 140.61 vs. 410.59 ± 304.34, p = 0.03 and 0.62 ± 0.39 vs. 1.13 ± 0.31, p = 0.02). In addition, ZIP2, ZIP3, and ZIP6 mRNA expressions were significantly lower in postmenopausal women compared with premenopausal women (mean ± SD mRNA expression in relative units, 1.11 ± 0.61 vs. 2.29 ± 1.20, p = 0.04; 2.32 ± 1.90 vs. 15.82 ± 12.97, p = 0.02 and 1.10 ± 0.80 vs. 5.73 ± 4.72, p = 0.03). ZnT9 protein expression in the stratum spinosum was significantly lower in postmenopausal women (p = 0.012). Zinc transporters were expressed differentially in the vaginal tissues. ZnT9 expression was significantly lower in postmenopausal women compared with premenopausal women.

Copper Isotopes and Copper to Zinc Ratio as Possible Biomarkers for Thyroid Cancer

Thyroid cancer is the most common endocrine cancer. There is no systematic screening for such cancer, and the current challenge is to find potential biomarkers to facilitate an early diagnosis. Copper (Cu) and zinc (Zn) are essential micronutrients involved in the proper functioning of the thyroid gland, and changes in their concentrations have been observed in the development of cancer. Previous studies have highlighted the potential ⁶⁵Cu/⁶³Cu ratio (δ⁶⁵Cu) to be a cancer biomarker. This study tests its sensitivity on plasma samples (n = 46) of Algerian patients with papillary thyroid carcinoma and a set of corresponding biopsies (n = 11). The δ⁶⁵Cu ratio in blood and tumor samples was determined using multi collector inductively coupled plasma-mass spectrometry (MC-ICP-MS), and their corresponding Cu and Zn plasma total concentrations using total reflection X-ray fluorescence (TXRF). Plasma concentrations of Cu were significantly higher (1346.1 ± 328.3 vs. 1060.5 ± 216.1 μg/L, p < 0.0001), and Zn significantly lower (942.1 ± 205.2 vs. 1027.9 ± 151.4 μg/L, p < 0.05) in thyroid cancer patients as compared to healthy controls (n = 50). Accordingly, the Cu/Zn ratio was significantly different between patients and controls (1.5 ± 0.4 vs. 1.0 ± 0.3, p < 0.0001). Furthermore, the δ⁶⁵Cu plasma levels of patients were significantly lower than healthy controls (p < 0.0001), whereas thyroid tumor tissues presented high δ⁶⁵Cu values. These results support the hypothesis that Cu isotopes and plasma trace elements may serve as suitable biomarkers of thyroid cancer diagnosis.

Activity-based photoacoustic probe for biopsy-free assessment of copper in murine models of Wilson's disease and liver metastasis

The development of high-performance photoacoustic (PA) probes that can monitor disease biomarkers in deep tissue has the potential to replace invasive medical procedures such as a biopsy. However, such probes must be optimized for in vivo performance and exhibit an exceptional safety profile. In this study, we have developed PACu-1, a PA probe designed for biopsy-free assessment (BFA) of hepatic Cu via photoacoustic imaging. PACu-1 features a Cu(I)-responsive trigger appended to an aza-BODIPY dye platform that has been optimized for ratiometric sensing. Owing to its excellent performance, we were able to detect basal levels of Cu in healthy wild-type mice as well as elevated Cu in a Wilson's disease model and in a liver metastasis model. To showcase the potential impact of PACu-1 for BFA, we conducted two blind studies in which we were able to successfully identify Wilson's disease animals from healthy control mice in each instance.

Evaluation of zinc and copper levels in vaginal tissues and whole blood: correlation with age

Background

Zinc and copper are essential trace elements and play a crucial role in the homeostasis of connective tissues. In this study, we aimed to define zinc and copper levels in the vaginal tissue and establish whether a correlation exists between the zinc and copper levels either or both in whole blood or vaginal tissue samples and whether the finding correlates with the age of the patient or at least with her menopausal status.

Methods

We collected whole blood and vaginal tissue samples from 32 women and measured their zinc and copper levels by inductively coupled plasma optical emission spectrometry. We have performed Student's t test to evaluate the differences in the mean levels of trace elements and multiple regression to evaluate the association between vaginal tissue zinc/copper levels and age, menopausal status, number of vaginal deliveries, and zinc/copper blood levels.

Results

Zinc levels were significantly higher in both the vaginal tissues and whole blood samples than copper levels (p < 0.01). In the vaginal tissue samples, a strong positive correlation could be detected between zinc and copper levels (r = 0.82, p < 0.01). In the vaginal tissue, a negative correlation was found for zinc and copper levels with the age of women (r = − 0.27, p = 0.04 and r = − 0.56, p < 0.01). Multiple linear regression model (age, menopausal status, vaginal delivery and copper/zinc blood levels) showed that only age remained a significant predictor for zinc and copper vaginal tissues levels (p = 0.03, 95% CI − 2.28 to − 0.06; p = 0.004, 95% CI − 1.76 to − 0.34).

Conclusions

Zinc and copper levels in the vaginal tissue decline with age. Out of the examined variables (age, menopausal status, vaginal delivery, and copper/zinc levels), only age is a significant predictor of vaginal zinc/copper levels.

Copper Concentrations in Breast Cancer: A Systematic Review and Meta-Analysis

Breast cancer is the most common neoplasm, comprising 16% of all women's cancers worldwide. Research of Copper (Cu) concentrations in various body specimens have suggested an association between Cu levels and breast cancer risks. This systematic review and meta-analysis summarize the results of published studies and examine this association. We searched the databases PubMed, Scopus, Web of Science, and Google Scholar and the reference lists of relevant publications. The Standardized Mean Differences (SMDs) between Cu levels in cancer cases and controls and corresponding Confidence Intervals (CIs), as well as I2 statistics, were calculated to examine heterogeneity. Following the specimens used in the original studies, the Cu concentrations were examined in three subgroups: serum or plasma, breast tissue, and scalp hair. We identified 1711 relevant studies published from 1984 to 2017. There was no statistically significant difference between breast cancer cases and controls for Cu levels assayed in any studied specimen; the SMD (95% CI) was -0.01 (-1.06 - 1.03; P = 0.98) for blood or serum, 0.51 (-0.70 - 1.73; P = 0.41) for breast tissue, and -0.88 (-3.42 - 1.65; P = 0.50) for hair samples. However, the heterogeneity between studies was very high (P < 0.001) in all subgroups. We did not find evidence for publication bias (P = 0.91). The results of this meta-analysis do not support an association between Cu levels and breast cancer. However, due to high heterogeneity in the results of original studies, this conclusion needs to be confirmed by well-designed prospective studies.

Single component photoresponsive fluorescent organic nanoparticles: a smart platform for improved biomedical and agrochemical applications

Single component photoresponsive fluorescent organic nanoparticles for the regulated release of anticancer drugs, antibacterial agents, gasotransmitters, and agrochemicals and as effective PDT agents.

Serum copper and zinc levels in breast cancer: A meta-analysis

BACKGROUND

More and more studies have investigated the relationship between serum copper (Cu) and/or zinc (Zn) levels and breast cancer (BC). However, the results are inconsistent. It is unclear whether the serum Cu to Zn ratio (Cu/Zn) is associated with BC risk. Therefore, we evaluated serum Cu and Zn concentrations, and Cu/Zn in BC through meta-analysis.

MATERIALS AND METHODS

Studies reporting serum Cu and/or Zn concentrations in BC patients and controls from 1991 to 2020 were identified from PubMed, CNKI, and Wanfang databases online. Based on a random effects model, summary standard mean differences (SMDs) and the corresponding 95 % confidence intervals (95 % CIs) were applied to compare the serum levels of Cu, Zn and Cu/Zn between BC patients and controls.

RESULTS

Thirty-six eligible studies involving 5747 female subjects were included. The present study illustrated that the BC patients had significantly higher serum Cu levels than healthy controls (HC) (SMD (95 % CI): 1.99(1.48, 2.49)) and patients with benign breast diseases (BD) (SMD (95 % CI): 0.99(0.38, 1.61)). However, Zn concentrations were statistically decreased in BC patients than HC (SMD (95 % CI): -1.20(-1.74, -0.66)) and BD (SMD (95 % CI): -1.13 (-1.73, -0.54)). Cu/Zn concentrations were remarkably increased in BC patients than HC (SMD (95 % CI): 2.75(1.79, 3.60)) and BD (SMD (95 % CI): 2.98(1.91, 4.05)) in some studies.

CONCLUSION

The results show that elevated serum levels of Cu and Cu/Zn, as well as decreased Zn might be associated with increased risk of breast cancer. These three parameters have the potential to distinguish breast cancer from benign breast diseases.

The Multifaceted Roles of Copper in Cancer: A Trace Metal Element with Dysregulated Metabolism, but Also a Target or a Bullet for Therapy

In the human body, copper (Cu) is a major and essential player in a large number of cellular mechanisms and signaling pathways. The involvement of Cu in oxidation-reduction reactions requires close regulation of copper metabolism in order to avoid toxic effects. In many types of cancer, variations in copper protein levels have been demonstrated. These variations result in increased concentrations of intratumoral Cu and alterations in the systemic distribution of copper. Such alterations in Cu homeostasis may promote tumor growth or invasiveness or may even confer resistance to treatments. Once characterized, the dysregulated Cu metabolism is pinpointing several promising biomarkers for clinical use with prognostic or predictive capabilities. The altered Cu metabolism in cancer cells and the different responses of tumor cells to Cu are strongly supporting the development of treatments to disrupt, deplete, or increase Cu levels in tumors. The metallic nature of Cu as a chemical element is key for the development of anticancer agents via the synthesis of nanoparticles or copper-based complexes with antineoplastic properties for therapy. Finally, some of these new therapeutic strategies such as chelators or ionophores have shown promising results in a preclinical setting, and others are already in the clinic.

The ZIP6/ZIP10 heteromer is essential for the zinc-mediated trigger of mitosis

Zinc has been known to be essential for cell division for over 40 years but the molecular pathways involved remain elusive. Cellular zinc import across biological membranes necessitates the help of zinc transporters such as the SLC39A family of ZIP transporters. We have discovered a molecular process that explains why zinc is required for cell division, involving two highly regulated zinc transporters, as a heteromer of ZIP6 and ZIP10, providing the means of cellular zinc entry at a specific time of the cell cycle that initiates a pathway resulting in the onset of mitosis. Crucially, when the zinc influx across this heteromer is blocked by ZIP6 or ZIP10 specific antibodies, there is no evidence of mitosis, confirming the requirement for zinc influx as a trigger of mitosis. The zinc that influxes into cells to trigger mitosis additionally changes the phosphorylation state of STAT3 converting it from a transcription factor to a protein that complexes with this heteromer and pS³⁸Stathmin, the form allowing microtubule rearrangement as required in mitosis. This discovery now explains the specific cellular role of ZIP6 and ZIP10 and how they have special importance in the mitosis process compared to other ZIP transporter family members. This finding offers new therapeutic opportunities for inhibition of cell division in the many proliferative diseases that exist, such as cancer.

Selective Inhibition of HIF1α Expression by ZnSO4 Has Antitumoral Effects in Human Melanoma

Zinc as an essential trace metal is a ubiquitous component of various molecules of the cell. Studies indicated that it may modulate functions of various cancer cell types, and can even inhibit metastasis formation in experimental models. In melanoma, zinc was shown to affect melanin production and to induce apoptosis. Using human melanoma cell lines, we have tested the effects of ZnSO₄ on cell proliferation, survival, migration as well as in vivo on experimental liver colony formation. We have found that ZnSO₄ has antiproliferative and proapoptotic effects in vitro. In SCID mice intraperitoneal administration of ZnSO₄ specifically inhibited liver colony formation without affecting primary tumor growth. To reveal the molecular mechanisms of action of zinc in human melanoma, we have tested mRNA expression of zinc finger transcription factors and found a strong inhibitory effect on HIF1α, as compared to WT1 whereas HIF2α and MTF1 expression was unaffected. Immunohistochemical detection of HIF1α protein in liver metastases confirmed its decreased nuclear expression after in vivo ZnSO₄ treatment. These data indicate that in human melanoma zinc administration may have an antimetastatic effect due to a selective downregulation of HIF1α.

Changes in serum level of trace elements in pulmonary tuberculosis patients during anti-tuberculosis treatment

INTRODUCTIONS

Tuberculosis is spreading throughout the globe, while it is a crucial cause of death in developing countries. In this study, trace elements concentrations and their alterations were determined in TB patients during anti-tuberculosis treatment period.

MATERIALS AND METHODS

We have collected blood samples from a total of 180 TB patients with pulmonary Tuberculosis, and 180 healthy controls in Sistan, Iran. The serum iron, copper, lead, calcium, arsenic and selenium concentrations were detected at the beginning of anti-TB chemotherapy, at the end of 2nd, 4th and 6th month after treatment initiation. Data were then analyzed using SPSS version 20.

RESULTS AND DISCUSSIONS

Although Ca, Pb, and As levels did not change during the treatment period, serum concentrations of Fe, Zn, Cu, and Se were diminished in TB patients significantly during treatment in comparison with controls (P < 0.001).We also found that there was a significant difference in the ^Cu/_Se and ^Cu/_Zn ratios in tuberculosis patients in comparison with healthy individuals (P < 0.001).

CONCLUSIONS

Trace elements serum concentrations are affected by TB infection and anti-TB therapy. Their serum levels were strongly perturbed during infection as well as anti-TB treatment.

Oxytocin-Monolayer-Based Impedimetric Biosensor for Zinc and Copper Ions

Zinc and copper are essential metal ions for numerous biological processes. Their levels are tightly maintained in all body organs. Impairment of the Zn²⁺ to Cu²⁺ ratio in serum was found to correlate with many disease states, including immunological and inflammatory disorders. Oxytocin (OT) is a neuropeptide, and its activity is modulated by zinc and copper ion binding. Harnessing the intrinsic properties of OT is one of the attractive ways to develop valuable metal ion sensors. Here, we report for the first time an OT-based metal ion sensor prepared by immobilizing the neuropeptide onto a glassy carbon electrode. The developed impedimetric biosensor was ultrasensitive to Zn²⁺ and Cu²⁺ ions at physiological pH and not to other biologically relevant ions. Interestingly, the electrochemical impedance signal of two hemicircle systems was recorded after the attachment of OT to the surface. These two semicircles suggest two capacitive regions that result from two different domains in the OT monolayer. Moreover, the change in the charge-transfer resistance of either Zn²⁺ or Cu²⁺ was not similar in response to binding. This suggests that the metal-dependent conformational changes of OT can be translated to distinct impedimetric data. Selective masking of Zn²⁺ and Cu²⁺ was used to allow for the simultaneous determination of zinc to copper ions ratio by the OT sensor. The OT sensor was able to distinguish between healthy control and multiple sclerosis patients diluted sera samples by determining the Zn/Cu ratio similar to the state-of-the-art techniques. The OT sensor presented herein is likely to have numerous applications in biomedical research and pave the way to other types of neuropeptide-derived sensors.

Medical applications of Cu, Zn, and S isotope effects

This review examines recent applications of stable copper, zinc and sulfur isotopes to medical cases and notably cancer. The distribution of the natural stable isotopes of a particular element among coexisting molecular species varies as a function of the bond strength, the ionic charge, and the coordination, and it also changes with kinetics. Ab initio calculations show that compounds in which a metal binds to oxygen- (sulfate, phosphate, lactate) and nitrogen-bearing moieties (histidine) favor heavy isotopes, whereas bonds with sulfur (cysteine, methionine) favor light isotopes. Oxidized cations (e.g., Cu(ii)) and low coordination numbers are expected to favor heavy isotopes relative to their reduced counterparts (Cu(i)) and high coordination numbers. Here we discuss the first observations of Cu, Zn, and S isotopic variations, three elements closely related along multiple biological pathways, with emphasis on serum samples of healthy volunteers and of cancer patients. It was found that heavy isotopes of Zn and to an even greater extent Cu are enriched in erythrocytes relative to serum, while the difference is small for sulfur. Isotopic variations related to age and sex are relatively small. The ⁶⁵Cu/⁶³Cu ratio in the serum of patients with colon, breast, and liver cancer is conspicuously low relative to healthy subjects. The characteristic time over which Cu isotopes may change with disease progression (a few weeks) is consistent with both the turnover time of the element and albumin half-life. A parallel effect on sulfur isotopes is detected in a few un-medicated patients. Copper in liver tumor tissue is isotopically heavy. In contrast, Zn in breast cancer tumors is isotopically lighter than in healthy breast tissue. ⁶⁶Zn/⁶⁴Zn is very similar in the serum of cancer patients and in controls. Possible reasons for Cu isotope variations may be related to the cytosolic storage of Cu lactate (Warburg effect), release of intracellular copper from cysteine clusters (metallothionein), or the hepatocellular and biosynthetic dysfunction of the liver. We suggest that Cu isotope metallomics will help evaluate the homeostasis of this element during patient treatment, notably by chelates and blockers of Cu trafficking, and understand the many biochemical pathways in which this element is essential.

GPER, IGF-IR, and EGFR transduction signaling are involved in stimulatory effects of zinc in breast cancer cells and cancer-associated fibroblasts

Zinc (Zn) is an essential trace mineral that contributes to the regulation of several cellular functions; however, it may be also implicated in the progression of breast cancer through different mechanisms. It has been largely reported that the classical estrogen receptor (ER), as well as the G protein estrogen receptor (GPER, previously known as GPR30) can exert a main role in the development of breast tumors. In the present study, we demonstrate that zinc chloride (ZnCl₂ ) involves GPER in the activation of insulin-like growth factor receptor I (IGF-IR)/epidermal growth factor receptor (EGFR)-mediated signaling, which in turn triggers downstream pathways like ERK and AKT in breast cancer cells, and main components of the tumor microenvironment namely cancer-associated fibroblasts (CAFs). Further corroborating these findings, ZnCl₂ stimulates a functional crosstalk of GPER with IGF-IR and EGFR toward the transcription of diverse GPER target genes. Then, we show that GPER contributes to the stimulatory effects induced by ZnCl₂ on cell-cycle progression, proliferation, and migration of breast cancer cells as well as migration of CAFs. Together, our data provide novel insights into the molecular mechanisms through which zinc may exert stimulatory effects in breast cancer cells and CAFs toward tumor progression. © 2016 Wiley Periodicals, Inc.

Basal and copper-induced expression of metallothionein isoform 1,2 and 3 genes in epithelial cancer cells: The role of tumor suppressor p53

Metallothioneins (MTs) are a ubiquitous low-molecular weight, cysteine rich proteins with a high affinity for metal ions. The expression and induction of MTs have been associated with protection against DNA damage, oxidative stress, and apoptosis. Our past research had shown that p53 is an important factor in metal regulation of MTs. The present study was undertaken to explore further the interrelationship between p53 and MTs. We investigated whether silencing of p53 could affect expression pattern of basal and copper induced metallothioneins. The silencing of wild-type p53 (wt-p53) in epithelial breast cancer MCF7 cells affected the basal level of MT-2A RNA, whereas the levels of MT-1A and MT-1X RNA remained largely unchanged. The expression of MT-3 was undetectable in MCF7 with either functional or silenced p53. MCF7 cells with silenced wt-p53 failed to upregulate MT-2A in response to copper and showed a reduced sensitivity toward copper induced cell apoptotic death. Similarly in MCF7-E6 and MDA-MB-231 cells, the presence of inactive/mutated p53 halted MT-1A and MT-2A gene expression in response to copper. Constitutive expression of MT-3 RNA was detectable in the presence of mutated p53 (mtp53). Transient transfection of MDA-MB-231 cells with wt-p53 enabled copper induced upregulation of both MT-1A and MT-2A but not basal level of MT-2A, MT-1E, MT-1X and MT-3. Inactivation of p53 in HepG2 cells amplified the basal expression of studied MT isoforms, including MT-3, as well as copper-induced mRNA expression of MTs except MT-1H and MT-3. Presented data demonstrate a direct relation between p53 and MT-1A and MT-2A and they also indicate that wt-p53 might be a negative regulator of MT-3 in epithelial cancer cells.

Changes in Copper, Zinc, and Malondialdehyde Levels and Superoxide Dismutase Activities in Pre-Eclamptic Pregnancies

BACKGROUND

Preeclampsia (PE) is a hypertensive disorder that occurs in 2% to 8% of pregnancies. Although numerous studies have investigated the etiology and pathophysiology of preeclampsia, the precise pathological mechanisms remain poorly understood. Hence, in the present study malondialdehyde (MDA) levels and SOD expression, and Cu and Zn concentrations and ratios were correlated with birth weights in pregnant women with and without PE, and in non-pregnant females of reproductive age.

MATERIAL AND METHODS

Malondialdehyde (MDA) levels and superoxide dismutase (SOD) activities were determined spectrophotometrically, and Cu and Zn levels were determined using atomic absorption spectrometry in serum from 42 non-pregnant women (NP), 40 healthy pregnant women (HP), and 38 pre-eclamptic pregnant (PE) women. Subsequently, Cu/Zn ratios were calculated and associations with birth weights were analyzed using Spearman correlations.

RESULTS

Cu, Zn, and MDA levels and Cu/Zn ratios were significantly higher in the PE group than in the HP and NP groups, and were significantly higher in the HP than in the NP group (p<0.001 and p<0.001; respectively). In contrast, serum Zn and SOD levels were significantly lower in the PE group than in HP and NP groups, and were significantly lower in the HP group than in the NP group (p<0.001 and p<0.001; respectively). However, only Cu and Zn levels were significantly associated with fetal birth weights (r=-0.433, p<0.001).

CONCLUSIONS

Serum Cu/Zn ratios may reflect vascular complications of PE, and the ensuing increases in lipid peroxidation may play important pathogenic roles.

Serum and hair zinc levels in breast cancer: a meta-analysis

Many studies have investigated the association between serum/hair zinc levels and breast cancer, but the results were inconsistent. To compare the serum and hair zinc levels in women with breast cancer and controls, we conducted a systematic literature search of PubMed, Web of Science, Cochrane Library and Embase to identify relevant studies with publication dates up through November 2014. Based on a random effects model, summary standard mean differences (SMDs) and the corresponding 95% confidence intervals (CIs) were used to compare the serum and hair zinc levels in women with breast cancer and controls. Fourteen studies that investigated serum zinc levels and seven studies that assessed hair zinc levels were included. Our study observed no difference in serum zinc levels between breast cancer cases and controls (SMD (95%CI): -0.65[-1.42, 0.13]). However, we determined that hair zinc levels were lower in women with breast cancer compared with those of controls (SMD (95%CI): -1.99[-3.46, -0.52]). In conclusion, this study was the first to provide evidence that hair zinc levels in female breast cancer patients are lower than in controls; however, there was no significant difference in serum zinc levels between female breast cancer patients and controls.

Analysis of serum levels of 15 trace elements in breast cancer patients in Shandong, China

Experimental and epidemiological studies suggest that serum levels of trace elements may be associated with breast cancer risk. We compared serum levels of 15 trace elements between breast cancer patients and normal controls from Shandong, China, for the first time to assess whether serum levels of trace elements were associated with breast cancer risk. Eighty-eight breast cancer patients and 84 healthy controls were enrolled in the study. A Spectraspan V direct current plasma atomic emission spectrometer was used to determine the serum levels of 15 trace elements including Zn, Mn, Al, Cd, Fe, Mg, Ca, Pb, Cu, Se, Ni, Ti, Co, Li, and Cr. Breast cancer patients had significantly higher serum levels of Cd (p = 0.000), Mg (p = 0.001), Cu (p = 0.000), Co (p = 0.006), and Li (p = 0.003) and borderline higher Cr (p = 0.052), while significantly lower Mn (p = 0.000), Al (p = 0.000), Fe (p = 0.000), and Ti (p = 0.000) compared to their matched controls. However, there were no significant differences in serum levels of Zn (p = 0.824), Ca (p = 0.711), Pb (p = 0.274), Se (p = 0.236), and Ni (p = 0.185) between the two groups. Our study showed a possible association between serum levels of trace elements and breast cancer risk in eastern China, though it warrants further investigations to confirm the association. If confirmed, modulation of trace elements may help reduce breast cancer risk.

Copper isotope effect in serum of cancer patients. A pilot study

Lower⁶⁵Cu/⁶³Cu ratios in the serum of colorectal and breast cancer patients relative to healthy individuals have potential diagnostic value.

Zinc: The Metal of Life

The importance of zinc was 1st reported for Aspergillus niger. It took over 75 y to realize that zinc is also an essential trace element for rats, and an additional 30 y went by before it was recognized that this was also true for humans. The adult body contains about 2 to 3 g of zinc. Zinc is found in organs, tissues, bones, fluids, and cells. It is essential for many physiological functions and plays a significant role in a number of enzyme actions in the living systems. Bioinformatics estimates report that 10% of the human proteome contains zinc-binding sites. Based on its role in such a plethora of cellular components, zinc has diverse biological functions from enzymatic catalysis to playing a crucial role in cellular neuronal systems. Thus, based on the various published studies and reports, it is pertinent to state that zinc is one of the most important essential trace metals in human nutrition and lifestyle. Its deficiency may severely affect the homeostasis of a biological system. This review compiles the role of zinc in prophylaxis/therapeutics and provides current information about its effect on living beings.

Serum and tissue zinc in epithelial malignancies: a meta-analysis

BACKGROUND AND OBJECTIVES

Current studies give us inconsistent results regarding the association of neoplasms and zinc(II) serum and tissues concentrations. The results of to-date studies using meta-analysis are summarized in this paper.

METHODS

Web of Science (Science citation index expanded), PubMed (Medline), Embase and CENTRAL were searched. Articles were reviewed by two evaluators; quality was assessed by Newcastle-Ottawa scale; meta-analysis was performed including meta-regression and publication bias analysis.

RESULTS

Analysis was performed on 114 case control, cohort and cross-sectional studies of 22737 participants. Decreased serum zinc level was found in patients with lung (effect size = -1.04), head and neck (effect size = -1.43), breast (effect size = -0.93), liver (effect size = -2.29), stomach (effect size = -1.59), and prostate (effect size = -1.36) cancers; elevation was not proven in any tumor. More specific zinc patterns are evident at tissue level, showing increase in breast cancer tissue (effect size = 1.80) and decrease in prostatic (effect size = -3.90), liver (effect size = -8.26), lung (effect size = -3.12), and thyroid cancer (effect size = -2.84). The rest of the included tumors brought ambiguous results, both in serum and tissue zinc levels across the studies. The association between zinc level and stage or grade of tumor has not been revealed by meta-regression.

CONCLUSION

This study provides evidence on cancer-specific tissue zinc level alteration. Although serum zinc decrease was associated with most tumors mentioned herein, further--prospective--studies are needed.

Matrix metalloproteinase-9 and the Cu/Zn ratio as ancillary diagnostic tools in distinguishing between the classical and follicular variants of papillary thyroid carcinoma

The most common histological variants of papillary thyroid carcinoma (PTC), classical (CPTC) and follicular (FPTC), have different diagnostic features, molecular biology, and prognosis. Matrix metalloproteinase-9 (MMP-9) endopeptidase which degrades the components of the extracellular matrix is essential in the invasive growth and metastasizing of malignant tumors. The serum copper (Cu)/zinc (Zn) ratios are sensitive diagnostic and prognostic indicators in oncology since Cu- and Zn-dependent enzymes play important roles in the genesis and the progression of tumors. The aim of this study was to examine the expressions of MMP-9 in tissues of CPTC and FPTC, as well as to determine the Cu/Zn ratios in the same samples. MMP-9 was determined immunohistochemically, and the concentrations of copper and zinc in thyroid tissue were determined by means of flame atomic absorption spectrometry. The results obtained revealed significantly higher expressions of MMP-9 in CPTC in comparison with FPTC, as well as higher Cu/Zn ratios in CPTC than in FPTC. Thus, determining MMP-9 activities and the Cu/Zn ratios could improve the accuracy of the standard histopathological diagnosis of these two types of PTC.

Effects of chronic chromium(vi) exposure on blood element homeostasis: an epidemiological study

One hundred chromate production workers chronically exposed to low-level of hexavalent chromium [Cr(vi)] and eighty healthy individuals free from Cr exposure were recruited to the study. Personal sampling of airborne Cr was conducted and Cr content was quantified by Flame Atomic Absorption Spectrometry (FAAS). At the end of the sampling shift, blood samples were collected and element concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS) for Cr, Cd, Cu, Mo and Se and inductively coupled plasma atomic emission spectrometry (ICP-AES) for Ca, Fe, Mg and Zn. According to our results, 90% of the chromate production workers were exposed to airborne Cr in a concentration lower than 50 μg m(-3), which is the threshold limit value recommended by the American Conference of Governmental Industrial Hygienists and Chinese Ministry of Health. After Cr(vi) exposure, a significant increase in blood Cr, Cd, Fe, Mg, Mo, Se and Zn concentrations was observed, as well as a significant decrease in Ca concentration. A decrease in blood Cu was only observed among female workers. Blood Cr concentrations of the exposed workers (median = 15.68 ng mL(-1)) was four times higher than that of the controls (median = 3.03 ng mL(-1)), and significantly correlated with airborne Cr (r = 0.568, P<0.001). In addition, the inter-element correlations exhibited significant differences between the two groups. Our findings of the related health effects suggested that the underlying mechanisms of chronic Cr(vi) exposure on blood element homeostasis might be partly explained by oxidative stress in the body, dysfunction of Fe metabolism and renal injury.

Trace elements and heavy metals in hair of stage III breast cancer patients

This prospective study was designed to compare the hair levels of 36 elements in 52 patients with stage III breast cancer to those of an equal number of healthy individuals. Principal component and cluster analysis were used for source of identification and apportionment of heavy metals and trace elements in these two groups. A higher average level of iron was found in samples from patients while controls had higher levels of calcium. Both patients and controls had elevated levels of tin, magnesium, zinc, and sodium. Almost all element values in cancer patients showed higher dispersion and asymmetry than in healthy controls. Between the two groups, there were statistically significant differences in the concentrations of silver, arsenic, gold, boron, barium, beryllium, calcium, cadmium, cerium, cobalt, cesium, gadolinium, manganese, nickel, lead, antimony, scandium, selenium, and zinc (p < 0.05). Strong positive correlations were found between lead and gold (r = 0.785) in the cancer group and between palladium and cobalt (r = 0.945) in the healthy individuals. Our results show that there are distinct patterns of heavy metals and trace elements in the hair of breast cancer patients in comparison to healthy controls. These results could be of significance in the diagnosis of breast cancer.

Intracellular delivery of the reactive oxygen species generating agent D-penicillamine upon conjugation to poly-L-glutamic acid

D-penicillamine is an aminothiol that is cytotoxic to cancer cells and generates dose dependent reactive oxygen species (ROS) via copper catalyzed oxidation. However, the delivery of D-pen to cancer cells remains a challenge due to its high hydrophilicity, highly reactive thiol group and impermeability to the cell membrane. To overcome this challenge, we investigated a novel poly-L-glutamic acid (PGA) conjugate of D-pen (PGA-D-pen) where D-pen was conjugated to PGA modified with 2-(2-pyridyldithio)-ethylamine (PDE) via disulfide bonds. Confocal microscopy and cell uptake studies showed that the fluorescently labeled PGA-D-pen was taken up by human leukemia cells (HL-60) in a time dependent manner. Treatment of HL-60, murine leukemia cells (P388) and human breast cancer cells (MDA-MB-468) with PGA-D-pen resulted in dose dependent cytotoxicity and elevation of intracellular ROS levels. PGA-D-pen induced apoptosis in HL-60 cells which was verified by Annexin V binding. The in vivo evaluation of the conjugate in the P388 murine leukemia model (intraperitoneal) resulted in significant enhancement in the survival of CD2F1 mice over vehicle control.

Fate of zinc in an electroplating sludge during electrokinetic treatments

Chemical structure of zinc in the electrokinetic treatments of an electroplating sludge has been studied by in situ extended X-ray absorption fine structural (EXAFS) and X-ray absorption near edge structural (XANES) spectroscopies in the present work. The least-square fitted XANES spectra indicate that the main zinc compounds in the sludge were ZnCO(3) (75%), ZnOSiO(2) (17%) and Zn(OH)(2) (7%). Zinc in the sludge possessed a Zn-O bond distance of 2.07 A with a coordination number (CN) of 5. In the second shells, the bond distance of Zn-(O)-Si was 3.05 A (CN=2). An increase of Zn-(O)-Si (0.05 A) with a decrease of its CN (from 5 to <1) was found in the early stage of the electrokinetic treatment. Prolong the electrokinetic treatment time to 180 min, about 34% of Zn(II) was dissolved into the aqueous phase and about 68% of Zn(II) in the sludge (or 23% of total zinc) was migrated to the cathode under the electric field (5 V cm(-1)). The dissolution and electromigration rates of Zn(II) in the sludge were 1.0 and 0.6 mmol h(-1)g(-1) sludge, respectively during the electrokinetic treatment. This work also exemplifies the utilization of in situ EXAFS and XANES for revealing speciation and possible reaction pathways during the course of zinc recycling from the sludge by electrokinetic treatments.

Enhanced intracellular delivery of the reactive oxygen species (ROS)-generating copper chelator D-penicillamine via a novel gelatin--D-penicillamine conjugate

D-Penicillamine (D-pen) is an established copper chelator. We have recently shown that the copper-catalyzed D-pen oxidation generates concentration-dependent hydrogen peroxide (H 2O 2). Additionally, D-pen coincubated with cupric sulfate resulted in cytotoxicity in human leukemia and breast cancer cells due to the extracellular generation of reactive oxygen species (ROS). The inherent physicochemical properties of D-pen such as its short in vivo half-life, low partition coefficient, and rapid metal catalyzed oxidation limit its intracellular uptake and the potential utility as an anticancer agent in vivo. Therefore, to enhance the intracellular delivery and to protect the thiol moiety of D-pen, we designed, synthesized, and evaluated a novel gelatin-D-pen conjugate. D-pen was covalently coupled to gelatin with a biologically reversible disulfide bond with the aid of a heterobifunctional cross-linker ( N-succinimidyl-3-(2-pyridyldithio)-propionate) (SPDP). Additionally, fluorescein-labeled gelatin-D-pen conjugate was synthesized for cell uptake studies. D-pen alone was shown not to enter leukemia cells. In contrast, the qualitative intracellular uptake of the conjugate in human leukemia cells (HL-60) was shown with confocal microscopy. The conjugate exhibited slow cell uptake (over the period of 48 to 72 h). A novel HPLC assay was developed to simultaneously quantify both D-pen and glutathione in a single run. The conjugate was shown to completely release D-pen in the presence of glutathione (1 mM) in approximately 3 h in PBS buffer, pH 7.4. The gelatin-D-pen conjugate resulted in significantly greater cytotoxicity compared to free D-pen, gelatin alone, and a physical mixture of gelatin and D-pen in human leukemia cells. Further studies are warranted to assess the potential of D-pen conjugate in the delivery of D-pen as a ROS generating anticancer agent.