Zinc and cancer: implications for LIV-1 in breast cancer

Antibody-drug conjugates in breast cancer

Antibody-drug conjugates (ADCs) have garnered significant attention as an innovative therapeutic strategy in cancer treatment. The mechanism of action for ADCs involves the targeted delivery of antibodies to specific receptors, followed by the release of cytotoxic payloads directly into tumor cells. In recent years, ADCs have made substantial progress in the treatment of breast cancer (BC), particularly demonstrating significant efficacy in the human epidermal growth factor receptor-2 (HER-2)-positive subgroup. Clinical evidence indicates that ADCs have notably improved treatment efficacy and survival outcomes for BC patients. However, challenges such as drug toxicities and the emergence of drug resistance necessitate further research and discussion. In this paper, we will summarize the advances in ADCs targeting various receptors in BC patients and explore the challenges and future directions in this field. We anticipate that the increasing availability of ADCs will lead to more effective and personalized treatment options for BC patients.

Zinc Influences the Efficacy of Betulinic Acid Treatment and Radiotherapy in Breast Cancer Cells

The trace element zinc influences a number of biological reactions, including cell growth, apoptosis, and DNA damage, which affect tumor therapy. The natural compound betulinic acid (BA) and its derivatives are known for their antiviral, antibacterial, and antitumor effects. Previous studies show that BA and 3-acetyl-28-sulfamoyloxybetulin (CAI3) have high cytotoxicity and induce radiosensitization in breast cancer cells. This study investigates the effects of zinc supplementation on treatment with BA or CAI3 and radiotherapy of breast cancer cell lines MDA-MB-231 and HS578T. Expression analysis shows that BA and CAI3 lead to altered expression of genes involved in zinc metabolism. Zinc supplementation affects cell survival and cell death alone and in combination with BA or CAI3 in both breast cancer cell lines. In MDA-MB-231 cells, zinc excess protects against ROS formation by BA or CAI3 and exhibits radioprotective effects compared to the single agent treatment. In contrast, in HS578T cells, zinc induces ROS formation but does not affect radiosensitivity. The variable effects of zinc on radiosensitivity highlight the importance of individualized treatment approaches. Although zinc has cytotoxic, pro-apoptotic, and anti-clonogenic effects, it seems worthwhile to consider its radioprotective properties when making treatment decisions in the case of adjuvant radiotherapy of breast cancer.

Evolution, classification, and mechanisms of transport, activity regulation, and substrate specificity of ZIP metal transporters

The Zrt/Irt-like protein (ZIP) family consists of ubiquitously expressed divalent d-block metal transporters that play central roles in the uptake, secretion, excretion, and distribution of several essential and toxic metals in living organisms. The past few years has witnessed rapid progress in the molecular basis of these membrane transport proteins. In this critical review, we summarize the research progress at the molecular level of the ZIP family and discuss the future prospects. Furthermore, an evolutionary path for the unique ZIP fold and a new classification of the ZIP family are proposed based on the presented structural and sequence analyses.

Micro- and Macronutrients in Endometrial Cancer-From Metallomic Analysis to Improvements in Treatment Strategies

Endometrial cancer is reported to be one of the most prevalent cancers of the female reproductive organs worldwide, with increasing incidence and mortality rates over the past decade. Early diagnosis is critical for effective treatment. Recently, there has been a growing focus on the role of nutrition and micronutrient and macronutrient status in patients with gynecologic cancers, including endometrial cancer. In the following paper, we have conducted an in-depth narrative literature review with the aim of evaluating the results of metallomic studies specifically concerning the micro- and macronutrient status of patients with endometrial cancer. The main objective of the paper was to analyze the results regarding the nutritional status of endometrial cancer patients and describe the role of chosen elements in the onset and progression of endometrial carcinogenesis. Further, we have focused on the evaluation of the usage of the described elements in the potential treatment of the abovementioned cancer, as well as the possible prevention of cancer considering proper supplementation of chosen elements in healthy individuals. Calcium supplementation has been proposed to reduce the risk of endometrial cancer, although some studies offer conflicting evidence. Deficiencies in phosphorus, selenium, and zinc have been inversely associated with endometrial cancer risk, suggesting they may play a protective role, whereas excessive levels of iron, copper, and cadmium have been positively correlated with increased risk. However, the molecular mechanisms by which these elements affect endometrial carcinogenesis are not fully understood, and current findings are often contradictory. Further research is needed to clarify these relationships and to evaluate the potential of nutritional interventions for the prevention and treatment of endometrial cancer.

Heavy metals in biological samples of cancer patients: a systematic literature review

The majority of the so-called heavy metals are suspected to be involved in a number of pathologies and play a role in human carcinogenesis. Some of them (i.e. arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg) and nickel (Ni)) have been defined as carcinogens, increasing the susceptibility of tumor development and progression in humans. Moreover, Ni, Cr, Cd, Hg, and Pb together with zinc (Zn) and iron (Fe), may be capable of stimulating the progression of breast cancer and reducing a patient's sensitivity to treatment through alterations to DNA methylation. In patients with gastric cancers, levels of various heavy metals are augmented and hypothesized to amplify the expression of the human epidermal growth factor receptor type 2 gene. Cd may increase the risk of lung cancer development and have a negative impact on the overall survival of lung cancer patients. To investigate the relation between heavy metals in biological samples and risk, occurrence and survival cancer individuals, a comprehensive review work was performed, with a focus on breast, lung, prostate and gastric cancers. An extensive search strategy was devised to ensure relevant literature could be identified, with the PECO framework being adopted to facilitate this and identify key search terms. As evidenced in this review, there is substantial data to support the hypothesis that heavy metals influence tumor development and progression. Unluckily the number of papers dealing with the determination of metals directly in samples from cancer tissues is still rather limited, so we decided to expand the scope of this review also to analyses carried out on other biological samples, as urine, plasma, hair, nail, etc. The studies reviewed showed that several limitations and current knowledge gaps are present in the literature that require further investigation to improve our comprehension of the impact of different heavy metals on tumorigenesis.

The interaction effects of zinc and polygenic risk score with benzo[a]pyrene exposure on lung cancer risk: A prospective case-cohort study among Chinese populations

The relationship of exposure to benzo[a]pyrene (BaP) with lung cancer risk has been firmly established, but whether this association could be modified by other environmental or genetic factors remains to be explored. To investigate whether and how zinc (Zn) and genetic predisposition modify the association between BaP and lung cancer, we performed a case-cohort study with a 5.4-year median follow-up duration, comprising a representative subcohort of 1399 participants and 359 incident lung cancer cases. The baseline concentrations of benzo[a]pyrene diol epoxide-albumin adduct (BPDE-Alb) and Zn were quantified. We also genotyped the participants and computed the polygenic risk score (PRS) for lung cancer. Our findings indicated that elevated BPDE-Alb and PRS were linked to increased lung cancer risk, with the HR (95%CI) of 1.54 (1.36, 1.74) per SD increment in ln-transformed BPDE-Alb and 1.27 (1.14, 1.41) per SD increment in PRS, but high plasma Zn level was linked to a lower lung cancer risk [HR (95%CI)=0.77 (0.66, 0.91) per SD increment in ln-transformed Zn]. There was evidence of effect modification by Zn on BaP-lung cancer association (P for multiplicative interaction = 0.008). As Zn concentrations increased from the lowest to the highest tertile, the lung cancer risk per SD increment in ln-transformed BPDE-Alb decreased from 2.07 (1.48, 2.89) to 1.33 (0.90, 1.95). Additionally, we observed a significant synergistic interaction of BPDE-Alb and PRS [RERI (95%CI) = 0.85 (0.03, 1.67)], with 42% of the incident lung cancer cases among individuals with high BPDE-Alb and high PRS attributable to their additive effect [AP (95%CI) = 0.42 (0.14, 0.69)]. This study provided the first prospective epidemiological evidence that Zn has protective effect against BaP-induced lung tumorigenesis, whereas high genetic risk can enhance the harmful effect of BaP. These findings may provide novel insight into the environment-environment and environment-gene interaction underlying lung cancer development, which may help to develop prevention and intervention strategies to manage BaP-induced lung cancer.

Zinc as a potential regulator of the BCR-ABL oncogene in chronic myelocytic leukemia cells

BACKGROUND

Generally, decreased zinc in the serum of tumor patients but increased zinc in tumor cells can be observed. However, the role of zinc homeostasis in myeloid leukemia remains elusive. BCR-ABL is essential for the initiation, maintenance, and progression of chronic myelocytic leukemia (CML). We are currently investigating the association between zinc homeostasis and CML.

METHODS

Genes involved in zinc homeostasis were examined using three GEO datasets. Western blotting and qPCR were used to investigate the effects of zinc depletion on BCR-ABL expression. Furthermore, the effect of TPEN on BCR-ABL promoter activity was determined using the dual-luciferase reporter assay. MRNA stability and protein stability of BCR-ABL were assessed using actinomycin D and cycloheximide.

RESULTS

Transcriptome data mining revealed that zinc homeostasis-related genes were associated with CML progression and drug resistance. Several zinc homeostasis genes were affected by TPEN. Additionally, we found that zinc depletion by TPEN decreased BCR-ABL mRNA stability and transcriptional activity in K562 CML cells. Zinc supplementation and sodium nitroprusside treatment reversed BCR-ABL downregulation by TPEN, suggesting zinc- and nitric oxide-dependent mechanisms.

CONCLUSION

Our in vitro findings may help to understand the role of zinc homeostasis in BCR-ABL regulation and thus highlight the importance of zinc homeostasis in CML.

The association between zinc and prostate cancer development: A systematic review and meta-analysis

BACKGROUND

Prostate cancer is affecting males globally, with several complications. Zinc can play roles in cancers. We aimed to clarify the association between zinc levels or intake with prostate cancer development.

METHODS

We searched PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science until May 1, 2023. We included case-controls and cross-sectionals that measured zinc level and/or intake in patients with prostate cancer or cohorts that evaluated the association between zinc and prostate cancer development. Studies that did not have a healthy control group were excluded. Joanna Briggs Institute was used for quality assessment. Publication bias was evaluated using Egger's and Begg's tests and funnel plot.

RESULTS

Overall, 52 studies (n = 44 case controls, n = 4 cohorts, and n = 4 cross sectionals) with a total number of 163909 participants were included. Serum (standardized mean difference (SMD): -1.11; 95% confidence interval (CI): -1.67, -0.56), hair (SMD: -1.31; 95% CI: -2.19, -0.44), and prostatic fluid or tissue zinc levels (SMD: -3.70; 95% CI: -4.90, -2.49) were significantly lower in prostate cancer patients. There were no significant differences in nail zinc level and zinc intake between those with prostate cancer and healthy controls. There was no publication bias except for serum and hair zinc levels based on Begg's and Egger's tests, respectively. The mean risk of bias scores were 4.61 in case-controls, eight in cohorts, and seven in cross-sectionals.

CONCLUSIONS

Overall, high zinc levels might have a protective role in prostate cancer, which can be used as a therapeutic or preventive intervention. Future large-scale studies are needed to confirm the association.

From zinc homeostasis to disease progression: Unveiling the neurodegenerative puzzle

Zinc is a crucial trace element in the human body, playing a role in various physiological processes such as oxidative stress, neurotransmission, protein synthesis, and DNA repair. The zinc transporters (ZnTs) family members are responsible for exporting intracellular zinc, while Zrt- and Irt-like proteins (ZIPs) are involved in importing extracellular zinc. These processes are essential for maintaining cellular zinc homeostasis. Imbalances in zinc metabolism have been linked to the development of neurodegenerative diseases. Disruptions in zinc levels can impact the survival and activity of neurons, thereby contributing to the progression of neurodegenerative diseases through mechanisms like cell apoptosis regulation, protein phase separation, ferroptosis, oxidative stress, and neuroinflammation. Therefore, conducting a systematic review of the regulatory network of zinc and investigating the relationship between zinc dysmetabolism and neurodegenerative diseases can enhance our understanding of the pathogenesis of these diseases. Additionally, it may offer new insights and approaches for the treatment of neurodegenerative diseases.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

Construction of a prognostic model for colorectal adenocarcinoma based on Zn transport-related genes identified by single-cell sequencing and weighted co-expression network analysis

Background

Colorectal cancer (CRC) is one of the most prevalent malignancies and the third most lethal cancer globally. The most reported histological subtype of CRC is colon adenocarcinoma (COAD). The zinc transport pathway is critically involved in various tumors, and its anti-tumor effect may be through improving immune function. However, the Zn transport pathway in COAD has not been reported.

Methods

The determination of Zn transport-related genes in COAD was carried out through single-cell analysis of the GSE 161277 obtained from the GEO dataset. Subsequently, a weighted co-expression network analysis of the TCGA cohort was performed. Then, the prognostic model was conducted utilizing univariate Cox regression and least absolute shrinkage and selection operator (LASSO) Cox regression analysis. Functional enrichment, immune microenvironment, and survival analyses were also carried out. Consensus clustering analysis was utilized to verify the validity of the prognostic model and explore the immune microenvironment. Ultimately, cell experiments, including CCK-8,transwell and scratch assays, were performed to identify the function of LRRC59 in COAD.

Results

According to the Zn transport-related prognostic model, the individuals with COAD in TCGA and GEO databases were classified into high- and low-risk groups. The group with low risk had a comparatively more favorable prognosis. Two groups had significant variations in the immune infiltration, MHC, and the expression of genes related to the immune checkpoint. The cell experiments indicated that the proliferation, migration, and invasion of the HCT-116, DLD-1, and RKO cell lines were considerably increased after LRRC59 knockdown. It proved that LRRC59 was indeed a protective factor for COAD.

Conclusion

A prognostic model for COAD was developed using zinc transport-related genes. This model can efficiently assess the immune microenvironment and prognosis of individuals with COAD. Subsequently, the function of LRRC59 in COAD was validated via cell experiments, highlighting its potential as a biomarker.

Zeolites with Divalent Ions as Carriers in the Delivery of Epigallocatechin Gallate

Epigallocatechin gallate (EGCG) is a compound with very high therapeutic potential in the treatment of osteoporosis and cancer. The disadvantages of this compound are its low stability and low bioavailability. Therefore, carriers for EGCG are sought to increase its use. In this work, new carriers are proposed, i.e., zeolites containing divalent ions of magnesium, calcium, strontium, and zinc in their structure. EGCG is retained on the carrier surface by strong interactions with divalent ions. Due to the presence of strong interactions, EGCG is released in a controlled manner from the carrier-ion-EGCG drug delivery system. The results obtained in this work confirm the effectiveness of the preparation of new carriers. EGCG is released from the carriers depending on the pH; hence, it can be used both in osteoporosis and in the treatment of cancer. The divalent ion used affects the sorption and release of the drug. The obtained results indicate the great potential of the proposed carriers and their advantage over the carriers described in the literature.

A non-destructive X-ray fluorescence method of analysis of formalin fixed-paraffin embedded biopsied samples for biomarkers for breast and colon cancer

In this work we present a methodology for the non-destructive elemental determination of formalin-fixed paraffin-embedded (FFPE) human tissue samples based on the Fundamental Parameters method for the quantification of micro Energy Dispersive X Ray Fluorescence (micro-EDXRF) area scans. This methodology intended to overcome two major constraints in the analysis of paraffin embedded tissue samples - retrieval of optimal region of analysis of the tissue within the paraffin block and the determination of the dark matrix composition of the biopsied sample. This way, an image treatment algorithm, based on R® tool to select the regions of the micro-EDXRF area scans was developed. Also, different dark matrix compositions were evaluated using varying combinations of H, C, N and O until the most accurate matrix was found: 8% H, 15% C, 1% N and 60% O for breast FFPE samples and 8% H, 23% C, 2% N and 55% O for colon. The developed methodology was applied to paired normal-tumour samples of breast and colon biopsied tissues in order to gauge potential elemental biomarkers for carcinogenesis in these tissues. The obtained results showed distinctive biomarkers for breast and for colon: there was a significant increase of P, S, K and Fe in both tissues, while a significant increase of Ca an Zn concentrations was also determined for breast tumour samples.

A Systematic Study on Zinc-Related Metabolism in Breast Cancer

Breast cancer has become the most common cancer worldwide. Despite the major advances made in the past few decades in the treatment of breast cancer using a combination of chemotherapy, endocrine therapy, and immunotherapy, the genesis, treatment, recurrence, and metastasis of this disease continue to pose significant difficulties. New treatment approaches are therefore urgently required. Zinc is an important trace element that is involved in regulating various enzymatic, metabolic, and cellular processes in the human body. Several studies have shown that abnormal zinc homeostasis can lead to the onset and progression of various diseases, including breast cancer. This review highlights the role played by zinc transporters in pathogenesis, apoptosis, signal transduction, and potential clinical applications in breast cancer. Additionally, the translation of the clinical applications of zinc and associated molecules in breast cancer, as well as the recent developments in the zinc-related drug targets for breast cancer treatment, is discussed. These developments offer novel insights into understanding the concepts and approaches that could be used for the diagnosis and management of breast cancer.

Human papillomavirus infection, cervical cancer and the less explored role of trace elements

Cervical cancer is an aggressive type of cancer affecting women worldwide. Many affected individuals rely on smear tests for the diagnosis, surgery, chemotherapy, or radiation for their treatment. However, due to a broad set of undesired results and side-effects associated with the existing protocols, the search for better diagnostic and therapeutic interventions is a never-ending pursuit. In the purview, the bio-concentration of trace elements (copper, selenium, zinc, iron, arsenic, manganese, and cadmium) is seen to fluctuate during the occurrence of cervical cancer and its progression from pre-cancerous to metastatic nature. Thus, during the occurrence of cervical cancer, the detection of trace elements and their supplementation will prove to be highly advantageous in developing diagnostic tools and therapeutics, respectively. This review provides a detailed overview of cervical cancer, its encouragement by human papillomavirus infections, the mechanism of pathology, and resistance. Majorly, the review emphasizes the less explored role of trace elements, their contribution to the growth and inhibition of cervical cancer. Numerous clinical trials have been listed, thereby providing a comprehensive reference to the exploration of trace elements in the management of cervical cancer.

Zincon-Modified CNTs Electrochemical Tool for Salivary and Urinary Zinc Detection

Recently, the abnormal level of zinc emerged as a powerful indicator or risk factor for metabolic, endocrine, neurodegenerative and cardiovascular diseases, including cancer. Electrochemical detection has been explored to quantify zinc in a precise, rapid, and non-expensive way; however, most of the current electrochemical systems lack in specificity. In this work we studied a highly selective and sensitive electrochemical method to detect quickly and reliably free zinc ions (Zn²⁺). The surface of the working electrode was modified with zincon electropolymerized on carbon nanotube (CNT) to enable the binding of zinc in complex body fluids. After being physicochemically characterized, the performances of the zincon-CNT complex was electrochemically assessed. Square Wave Voltammetry (SWV) was used to determine the calibration curve and the linear range of zinc quantification in artificial saliva and urine. This zincon- CNT system could specifically quantify mobile Zn²⁺ in salivary and urinary matrices with a sensitivity of ~100 ng·mL^-1 and a limit of detection (LOD) of ~20 ng·mL^-1. Zincon-modified CNT presented as a desirable candidate for the detection and quantification of free zinc in easily body fluids that potentially can become a diagnostic non-invasive testing platform.

Dietary Trace Element Intake and Risk of Breast Cancer: A Mini Review

Trace elements are essentially required for various physiological and metabolic functions, and any disturbance in the trace elements homeostasis may result in the development of chronic diseases including breast cancer. Breast cancer is the most prevalent cancer type reported in women equally affecting both the high-income and low-income countries. This review therefore aimed to evaluate the impact of dietary trace element intake in relation to the incidence of breast cancer. We focused on five trace elements, thus emphasizing dietary selenium, zinc, iron, copper, and cadmium intake and risk of breast cancer. A systematic approach was applied to perform this review through entering a search term in PubMed and Scopus databases. A total of 24 articles were included after meeting the inclusion and exclusion criteria. Most of the studies regarding dietary iron intake showed a detrimental effect of increased dietary heme iron on breast cancer incidence risk. In addition, there is a limited evidence of high dietary intake of selenium and zinc to reduce the risk of breast cancer. Also, a few studies showed a relationship between high cadmium consumption and risk of breast cancer. More studies related to cadmium and copper exposure are needed to confirm this relationship. As a result, the findings of this review suggested that high dietary heme iron is a potential risk factor for breast cancer.

Zinc's Association with the CmPn/CmP Signaling Network in Breast Cancer Tumorigenesis

It is well-known that serum and cellular concentrations of zinc are altered in breast cancer patients. Specifically, there are notable zinc hyper-aggregates in breast tumor cells when compared to normal mammary epithelial cells. However, the mechanisms responsible for zinc accumulation and the consequences of zinc dysregulation are poorly understood. In this review, we detailed cellular zinc regulation/dysregulation under the influence of varying levels of sex steroids and breast cancer tumorigenesis to try to better understand the intricate relationship between these factors based on our current understanding of the CmPn/CmP signaling network. We also made some efforts to propose a relationship between zinc signaling and the CmPn/CmP signaling network.

Zinc transporter LIV1: A promising cell surface target for triple negative breast cancer

Breast cancer is one of the leading causes contributing to the global cancer burden. The triple negative breast cancer (TNBC) molecular subtype accounts for the most aggressive type. Despite progression in therapeutic options and prognosis in breast cancer treatment options, there remains a high rate of distant relapse. With advancements in understanding the role of zinc and zinc carriers in the prognosis and treatment of the disease, the scope of precision treatment/targeted therapy has been expanded. Zinc levels and zinc transporters play a vital role in maintaining cellular homeostasis, tumor surveillance, apoptosis, and immune function. This review focuses on the zinc transporter, LIV1, as an essential target for breast cancer prognosis and emerging treatment options. Previous studies give an insight into the role of LIV1 in fulfilling the most important hallmarks of cancer such as apoptosis, metastasis, invasion, and evading the immune system. Normal tissue expression of LIV1 is limited. Higher expression of LIV1 has been linked to Epithelial-Mesenchymal Transition, histological grade of cancer, and early node metastasis. LIV1 was found to be one of the attractive targets in the therapeutic hunt for TNBCs. TNBCs are an immunogenic breast cancer subtype. As zinc transporters are known to serve as the metabolic gatekeepers of immune cells, this review bridges tumor infiltrating lymphocytes, TNBC and LIV1. In addition, the suitability of LIV1 as an antibody-drug conjugate (Seattle genetics [SGN]-LIV1A) target in TNBC, represents a promising strategy for patients. Early clinical trial results reveal that this novel agent reduces tumor burden by inducing mitotic arrest, immunomodulation, and immunogenic cell death, warranting further investigation of SGN-LIV1A in combination with immuno-oncology agents. Priming the patient's immune response in combination with SGN-LIV1A could eventually change the landscape for the TNBC patient population.

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.

Role of SLC39A6 in the development and progression of liver cancer

Liver cancer is one of the most common malignant solid tumor types worldwide. The solute carrier (SLC)39A family is a main member of the SLC group of membrane transport proteins, which transfer zinc to the cytoplasm when cells are depleted of zinc; thus, it may provide a novel therapeutic target for human cancer. However, the prognostic value of SLC39A genes in patients with liver cancer has remained elusive. Therefore, the present study aimed to explore whether SLC39A family genes are associated with the survival rate of patients with liver cancer and to investigate the role of key genes of the SLC39A family in liver cancer. The mRNA expression of the SLC39A family in liver cancer was obtained from the UALCAN database. Survival curve analysis was performed to investigate the prognostic value of SLC39A family genes in the overall survival of patients with liver cancer. In addition to the bioinformatics analysis, SLC39A6 was knocked down in HepG2 and Hep3B cells to examine the effect on the proliferation, migration and invasion of liver cancer cells. The results suggested that SLC39A6 was significantly upregulated in liver cancer tissues compared with normal liver tissues. High expression of SLC39A6 was significantly associated with poor overall survival of patients with liver cancer. Furthermore, knockdown of SLC39A6 inhibited the proliferation, migration and invasion of liver cancer cells in vitro and in vivo. Collectively, the results of the present study suggested that SLC39A6 may be a promising prognostic biomarker for liver cancer and is associated with the proliferation, migration and invasion of liver cancer.

Pan-Cancer Analysis of the Solute Carrier Family 39 Genes in Relation to Oncogenic, Immune Infiltrating, and Therapeutic Targets

Background: Emerging pieces of evidence demonstrated that the solute carrier family 39 (SLC39A) members are critical for the oncogenic and immune infiltrating targets in multiple types of tumors. However, the precise relationship between the SLC39A family genes and clinical prognosis as well as the pan-cancer tumor cell infiltration has not been fully elucidated.

Methods: In this study, the pan-cancer expression profile, genetic mutation, prognostic effect, functional enrichment, immune infiltrating, and potential therapeutic targets of the SLC39A family members were investigated by analyzing multiple public databases such as the Oncomine, TIMER, GEPIA, cBioPortal, KM-plotter, PrognoScan, GeneMANIA, STRING, DAVID, TIMER 2.0, and CellMiner databases.

Results: The expression levels of most SLC39 family genes in the tumor tissues were found to be significantly upregulated compared to the normal group. In mutation analysis, the mutation frequencies of SLC39A4 and SLC39A1 were found to be higher among all the members (6 and 4%, respectively). Moreover, the overall mutation frequency of the SLC39A family genes ranged from 0.8 to 6% pan-cancer. Also, the function of the SLC39A highly related genes was found to be enriched in functions such as zinc II ion transport across the membrane, steroid hormone biosynthesis, and chemical carcinogenesis. In immune infiltration analysis, the expression level of the SLC39A family genes was found to be notably related to the immune infiltration levels of six types of immune cells in specific types of tumors. In addition, the SLC39A family genes were significantly related to the sensitivity or resistance of 63 antitumor drugs in a variety of tumor cell lines.

Conclusion: These results indicate that the SLC39 family genes are significant for determining cancer progression, immune infiltration, and drug sensitivity in multiple cancers. This study, therefore, provides novel insights into the pan-cancer potential targets of the SLC39 family genes.

Zinc Triggered Release of Encapsulated Cargo from Liposomes via a Synthetic Lipid Switch

Liposomes are effective nanocarriers due to their ability to encapsulate and deliver a wide variety of therapeutics. However, therapeutic potential would be improved by enhanced control over the release of drug cargo. Zinc ions provide exciting new targets for stimuli-responsive lipid design due to their overly abundant concentrations associated with diseased cells. Herein, we report zinc-triggered release of liposomal contents exploiting synthetic lipid switches designed to undergo conformational changes in the presence of this ion. Initially, Nile red leakage assays were conducted that validated successful dose-dependent triggering of release using zinc-responsive lipids (ZRLs). In addition, dynamic light scattering and confocal microscopy experiments showed that zinc treatment led to morphological changes in lipid nanoparticles only when ZRLs were present in formulations. Next, zinc-binding experiments conducted in a solution (NMR, MS) or membrane (zeta potential) context confirmed ZRL-Zn complexation. Finally, polar cargo release from liposomes was achieved. The results from these wide-ranging experiments using four different compounds indicated that zinc-responsive properties varied based on ZRL structure, providing insights into the structural requirements for activity. This work has established zinc-responsive liposomal platforms toward the development of clinical triggered release formulations.

Development of camelid monoclonal nanobody against SLC39A6 zinc transporter protein

Objectives

SLC39A6 (solute carrier family 39) or LIV-1, is a zinc-transporter protein associated with estrogen-positive breast cancer and its metastatic spread. Significantly there is a direct relation between high zinc intake and unregulated cell proliferation and cancers. Blocking SLC39A6 protein may result in reduced metastasis and proliferation in many malignant tumors. This study aimed to develop an anti-SLC39A6 nanobody that is able to detect and block the SLC39A6 protein on the surface of cancerous cells.

Materials and Methods

The recombinant SLC39A6 was expressed and used for camel immunization. The VHH library was constructed and screened for SLC39A6-specific nanobody. Then, the strength of nanobody in SLC39A6 detection was evaluated by Western blotting and flow cytometry.

Results

We showed the ability of SLC39A6 specific Nanobody (C3) to detect SLC39A6 by Western blotting and flow cytometry. Furthermore, the C3 nanobody potently inhibits cell proliferation in MTT assay.

Conclusion

These data show the potential of SLC39A6-specific nanobody for the blockade of zinc transporter protein and provide a basis for the development of novel cancer therapeutics.

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.

ZIP10 drives osteosarcoma proliferation and chemoresistance through ITGA10-mediated activation of the PI3K/AKT pathway

Background

The zinc transporters Zrt- and Irt-related protein (ZIP/SLC39) are overexpressed in human tumors and correlate with poor prognosis; however, their contributions to carcinogenesis and chemoresistance in osteosarcoma (OS) remain unclear.

Methods

We collected 64 OS patient tissues with (n = 12) or without (n = 52) chemotherapy. The expression levels of ZIP10 were measured by immunohistochemistry and applied to prognostic analysis. ZIP10 was knocked down or overexpressed in OS cell lines to explore its effect on proliferation and chemoresistance. RNA sequencing, quantitative real-time PCR, and western blotting analysis were performed to explore ZIP10-regulated downstream target genes. A xenograft mouse model was established to evaluate the mechanisms by which ZIP10 modulates chemoresistance in OS cells.

Results

The expression of ZIP10 was significantly induced by chemotherapy and highly associated with the clinical outcomes of OS. Knockdown of ZIP10 suppressed OS cell proliferation and chemoresistance. In addition, ZIP10 promoted Zn content-induced cAMP-response element binding protein (CREB) phosphorylation and activation, which are required for integrin α10 (ITGA10) transcription and ITGA10-mediated PI3K/AKT pathway activation. Importantly, ITGA10 stimulated PI3K/AKT signaling but not the classical FAK or SRC pathway. Moreover, overexpression of ZIP10 promoted ITGA10 expression and conferred chemoresistance. Treatment with the CREB inhibitor 666–15 or the PI3K/AKT inhibitor GSK690693 impaired tumor chemoresistance in ZIP10-overexpressing cells. Finally, a xenograft mouse model established by subcutaneous injection of 143B cells confirmed that ZIP10 mediates chemotherapy resistance in OS cells via the ZIP10-ITGA10-PI3K/AKT axis.

Conclusions

We demonstrate that ZIP10 drives OS proliferation and chemoresistance through ITGA10-mediated activation of the PI3K/AKT pathway, which might serve as a target for OS treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02146-8.

The ion channel TRPM7 regulates zinc-depletion-induced MDMX degradation

Zinc deficiency has been linked to human diseases, including cancer. MDMX, a crucial zinc-containing negative regulator of p53, has been found to be amplified or overexpressed in various cancers and implicated in the cancer initiation and progression. We report here that zinc depletion by the ion chelator TPEN or Chelex resin results in MDMX protein degradation in a ubiquitination-independent and 20S proteasome-dependent manner. Restoration of zinc led to recovery of cellular levels of MDMX. Further, TPEN treatment inhibits growth of the MCF-7 breast cancer cell line, which is partially rescued by overexpression of MDMX. Moreover, in a mass-spectrometry-based proteomics analysis, we identified TRPM7, a zinc-permeable ion channel, as a novel MDMX-interacting protein. TRPM7 stabilizes and induces the appearance of faster migrating species of MDMX on SDS-PAGE. Depletion of TRPM7 attenuates, while TRPM7 overexpression facilitates, the recovery of MDMX levels upon adding back zinc to TPEN-treated cells. Importantly, we found that TRPM7 inhibition, like TPEN treatment, decreases breast cancer cell MCF-7 proliferation and migration. The inhibitory effect on cell migration upon TRPM7 inhibition is also partially rescued by overexpression of MDMX. Together, our data indicate that TRPM7 regulates cellular levels of MDMX in part by modulating the intracellular Zn²⁺ concentration to promote tumorigenesis.

Multi-Modal Mass Spectrometric Imaging of Uveal Melanoma

Matrix assisted laser desorption ionisation mass spectrometry imaging (MALDI-MSI), was used to obtain images of lipids and metabolite distribution in formalin fixed and embedded in paraffin (FFPE) whole eye sections containing primary uveal melanomas (UM). Using this technique, it was possible to obtain images of lysophosphatidylcholine (LPC) type lipid distribution that highlighted the tumour regions. Laser ablation inductively coupled plasma mass spectrometry images (LA-ICP-MS) performed on UM sections showed increases in copper within the tumour periphery and intratumoural zinc in tissue from patients with poor prognosis. These preliminary data indicate that multi-modal MSI has the potential to provide insights into the role of trace metals and cancer metastasis.

Immunotherapy for Breast Cancer Treatment

Breast cancer, as a heterogeneous disease, includes a wide range of pathological and clinical behaviors. Current treatment protocols, including radiotherapy, chemotherapy, and hormone replacement therapy, are mainly associated with poor response and high rate of recurrence. Therefore, more efforts are needed to develop alternative therapies for this type of cancer. Immunotherapy, as a novel strategy in cancer treatment, has a potential in treating breast cancer patients. Although breast cancer has long been considered problematic to treat with immunotherapy, as it is immunologically "cold," numerous newer preclinical and clinical reports now recommend that immunotherapy has the capability to treat breast cancer patients. In this review, we highlight the different immunotherapy strategies in breast cancer treatment.

Co-Opting Host Receptors for Targeted Delivery of Bioconjugates-From Drugs to Bugs

Bioconjugation has allowed scientists to combine multiple functional elements into one biological or biochemical unit. This assembly can result in the production of constructs that are targeted to a specific site or cell type in order to enhance the response to, or activity of, the conjugated moiety. In the case of cancer treatments, selectively targeting chemotherapies to the cells of interest limit harmful side effects and enhance efficacy. Targeting through conjugation is also advantageous in delivering treatments to difficult-to-reach tissues, such as the brain or infections deep in the lung. Bacterial infections can be more selectively treated by conjugating antibiotics to microbe-specific entities; helping to avoid antibiotic resistance across commensal bacterial species. In the case of vaccine development, conjugation is used to enhance efficacy without compromising safety. In this work, we will review the previously mentioned areas in which bioconjugation has created new possibilities and advanced treatments.

Immunotherapy for Breast Cancer Treatment

Breast cancer, as a heterogeneous disease, includes a wide range of pathological and clinical behaviors. Current treatment protocols, including radiotherapy, chemotherapy, and hormone replacement therapy, are mainly associated with poor response and high rate of recurrence. Therefore, more efforts are needed to develop alternative therapies for this type of cancer. Immunotherapy, as a novel strategy in cancer treatment, has a potential in treating breast cancer patients. Although breast cancer has long been considered problematic to treat with immunotherapy, as it is immunologically "cold," numerous newer preclinical and clinical reports now recommend that immunotherapy has the capability to treat breast cancer patients. In this review, we highlight the different immunotherapy strategies in breast cancer treatment.

Oestrogen-regulated protein SLC39A6: a biomarker of good prognosis in luminal breast cancer

PURPOSE

The outcome of the luminal oestrogen receptor-positive (ER +) subtype of breast cancer (BC) is highly variable and patient stratification needs to be refined. We assessed the prognostic significance of oestrogen-regulated solute carrier family 39 member 6 (SLC39A6) in BC, with emphasis on ER + tumours.

MATERIALS AND METHODS

SLC39A6 mRNA expression and copy number alterations were assessed using the METABRIC cohort (n = 1980). SLC39A6 protein expression was evaluated in a large (n = 670) and annotated series of early-stage (I-III) operable BC using tissue microarrays and immunohistochemistry. The associations between SLC39A6 expression and clinicopathological parameters, patient outcomes and other ER-related markers were evaluated using Chi-square tests and Kaplan-Meier curves.

RESULTS

High SLC39A6 mRNA and protein expression was associated with features characteristic of less aggressive tumours in the entire BC cohort and ER + subgroup. SLC39A6 protein expression was detected in the cytoplasm and nuclei of the tumour cells. High SLC39A6 nuclear expression and mRNA levels were positively associated with ER + tumours and expression of ER-related markers, including the progesterone receptor, forkhead box protein A1 and GATA binding protein 3. In the ER + luminal BC, high SLC39A6 expression was independently associated with longer BC-specific survival (BCSS) (P = 0.015, HR 0.678, 95% CI 0.472‒0.972) even in those who did not receive endocrine therapy (P = 0.001, HR 0.701, 95% CI 0.463‒1.062).

CONCLUSION

SLC39A6 may be prognostic for a better outcome in ER + luminal BC. Further functional studies to investigate the role of SLC39A6 in ER + luminal BC are warranted.

Time- and Zinc-Related Changes in Biomechanical Properties of Human Colorectal Cancer Cells Examined by Atomic Force Microscopy

Simple Summary

We aimed to study how cellular zinc status (adequate vs. deficiency), closely related to colorectal cancer, does affect the nanomechanical properties of cell lines HT-29 and HT-29-MTX during their early proliferation (24–96 h). These properties and their variations can be characterized by means of Atomic Force Microscopy (AFM), a technique that allows perpendicular indentation of cells with a sharp nanometric tip, under controlled speed and load, while recording the real time variation of tip-to-cell interacting forces on approach, contact, and retraction segments. From each of these sections, complete information about the respective elastic modulus, relaxation behavior, and adhesion is extracted, thus identifying cell line- and zinc-related nanomechanical fingerprints. Our results show how the impact of zinc deficiency on the mechanical response of the cells underlines the relevance of monitoring the nutritional zinc status of tumor samples when analyzing cancerous tissues or single cells with AFM, particularly regarding the development and validation of biomechanical fingerprints as diagnostic markers for cancer.

Abstract

Monitoring biomechanics of cells or tissue biopsies employing atomic force microscopy (AFM) offers great potential to identify diagnostic biomarkers for diseases, such as colorectal cancer (CRC). Data on the mechanical properties of CRC cells, however, are still scarce. There is strong evidence that the individual zinc status is related to CRC risk. Thus, this study investigates the impact of differing zinc supply on the mechanical response of the in vitro CRC cell lines HT-29 and HT-29-MTX during their early proliferation (24–96 h) by measuring elastic modulus, relaxation behavior, and adhesion factors using AFM. The differing zinc supply severely altered the proliferation of these cells and markedly affected their mechanical properties. Accordingly, zinc deficiency led to softer cells, quantitatively described by 20–30% lower Young’s modulus, which was also reflected by relevant changes in adhesion and rupture event distribution compared to those measured for the respective zinc-adequate cultured cells. These results demonstrate that the nutritional zinc supply severely affects the nanomechanical response of CRC cell lines and highlights the relevance of monitoring the zinc content of cancerous cells or biopsies when studying their biomechanics with AFM in the future.

Zinc, ω-3 polyunsaturated fatty acids and vitamin D: An essential combination for prevention and treatment of cancers

Zinc, ω-3 polyunsaturated fatty acids (PUFAs) and vitamin D are essential nutrients for health, maturation and general wellbeing. Extensive literature searches have revealed the widespread similarity in molecular biological properties of zinc, ω-3 PUFAs and vitamin D, and their similar anti-cancer properties, even though they have different modes of action. These three nutrients are separately essential for good health, especially in the aged. Zinc, ω-3 PUFAs and vitamin D are inexpensive and safe as they are fundamentally natural and have the properties of correcting and inhibiting undesirable actions without disturbing the normal functions of cells or their extracellular environment. This review of the anticancer properties of zinc, ω-3 PUFAs and vitamin D is made in the context of the hallmarks of cancer. The anticancer properties of zinc, ω-3 PUFAs and vitamin D can therefore be used beneficially through combined treatment or supplementation. It is proposed that sufficiency of zinc, ω-3 PUFAs and vitamin D is a necessary requirement during chemotherapy treatment and that clinical trials can have questionable integrity if this sufficiency is not checked and maintained during efficacy trials.

The role of labile Zn2+ and Zn2+-transporters in the pathophysiology of mitochondria dysfunction in cardiomyocytes

An important energy supplier of cardiomyocytes is mitochondria, similar to other mammalian cells. Studies have demonstrated that any defect in the normal processes controlled by mitochondria can lead to abnormal ROS production, thereby high oxidative stress as well as lack of ATP. Taken into consideration, the relationship between mitochondrial dysfunction and overproduction of ROS as well as the relation between increased ROS and high-level release of intracellular labile Zn²⁺, those bring into consideration the importance of the events related with those stimuli in cardiomyocytes responsible from cellular Zn²⁺-homeostasis and responsible Zn²⁺-transporters associated with the Zn²⁺-homeostasis and Zn²⁺-signaling. Zn²⁺-signaling, controlled by cellular Zn²⁺-homeostatic mechanisms, is regulated with intracellular labile Zn²⁺ levels, which are controlled, especially, with the two Zn²⁺-transporter families; ZIPs and ZnTs. Our experimental studies in mammalian cardiomyocytes and human heart tissue showed that Zn²⁺-transporters localizes to mitochondria besides sarco(endo)plasmic reticulum and Golgi under physiological condition. The protein levels as well as functions of those transporters can re-distribute under pathological conditions, therefore, they can interplay among organelles in cardiomyocytes to adjust a proper intracellular labile Zn²⁺ level. In the present review, we aimed to summarize the already known Zn²⁺-transporters localize to mitochondria and function to stabilize not only the cellular Zn²⁺ level but also cellular oxidative stress status. In conclusion, one can propose that a detailed understanding of cellular Zn²⁺-homeostasis and Zn²⁺-signaling through mitochondria may emphasize the importance of new mitochondria-targeting agents for prevention and/or therapy of cardiovascular dysfunction in humans.

Zinc distribution within breast cancer tissue of different intrinsic subtypes

PURPOSE

To show feasibility of laser ablation inductively coupled mass spectrometry (LA-ICPMS) for analysis of zinc content and concentration in breast cancer tissue and to correlate this with validated prognostic and predictive markers, i.e. histological grading and expression of steroid receptors (estrogen receptor, ER; progesterone receptor, PR) and human epidermal growth-factor receptor 2 (Her2).

METHODS

28 samples of human invasive ductal breast cancer tissue were subclassified into groups of four different intrinsic subtypes according to the expression of ER, PR and Her2 by immunohistological staining and then analyzed for zinc content and distribution by LA-ICPMS applying a calibration technique based on spiked polyacrylamide gels. A correlation of zinc concentration with histological grading and molecular subtypes was analyzed.

RESULTS

Consistent with results of a pilot-study LA-ICPMS was feasible to show zinc accumulation in cancerous tissue, even more adjacent healthy stroma was with proportional increase of zinc. Zinc levels were most elevated in triple-positive (TPBC) and in triple-negative (TNB) breast cancers.

CONCLUSION

LA-ICPMS was feasible to confirm a connection between zinc and grade of malignancy; furthermore, focusing on a correlation of zinc and intrinsic breast cancer subtypes, LA-ICPMS depicted an upwards trend of zinc for "high-risk-cancers" with highest levels in Her2-positive and in triple-negative (TNBC) disease. The currently uncommon alliance of clinicians and analytical chemists in basic research is most promising to exploit the full potential of diagnostic accuracy in the efforts to solve the enigma of breast cancer initiation and course of disease.

Why and how to investigate the role of protein phosphorylation in ZIP and ZnT zinc transporter activity and regulation

Zinc is required for the regulation of proliferation, metabolism, and cell signaling. It is an intracellular second messenger, and the cellular level of ionic, mobile zinc is strictly controlled by zinc transporters. In mammals, zinc homeostasis is primarily regulated by ZIP and ZnT zinc transporters. The importance of these transporters is underscored by the list of diseases resulting from changes in transporter expression and activity. However, despite numerous structural studies of the transporters revealing both zinc binding sites and motifs important for transporter function, the exact molecular mechanisms regulating ZIP and ZnT activities are still not clear. For example, protein phosphorylation was found to regulate ZIP7 activity resulting in the release of Zn2+ from intracellular stores leading to phosphorylation of tyrosine kinases and activation of signaling pathways. In addition, sequence analyses predict all 24 human zinc transporters to be phosphorylated suggesting that protein phosphorylation is important for regulation of transporter function. This review describes how zinc transporters are implicated in a number of important human diseases. It summarizes the current knowledge regarding ZIP and ZnT transporter structures and points to how protein phosphorylation seems to be important for the regulation of zinc transporter activity. The review addresses the need to investigate the role of protein phosphorylation in zinc transporter function and regulation, and argues for a pressing need to introduce quantitative phosphoproteomics to specifically target zinc transporters and proteins involved in zinc signaling. Finally, different quantitative phosphoproteomic strategies are suggested.

Association between selenium intake and breast cancer risk: results from the Women's Health Initiative

PURPOSE

It has been hypothesized that selenium (Se) can prevent cancer, and that Se deficiency may be associated with an increased risk of breast cancer. However, findings from epidemiological studies have been inconsistent. The objective of this study was to assess the association between Se intake and risk of breast cancer in the Women's Health Initiative (WHI).

METHODS

This study included 145,033 postmenopausal women 50-79 years who completed baseline questionnaires between October 1993 and December 1998, which addressed dietary and supplemental Se intake and breast cancer risk factors. The association between baseline Se intake and incident breast cancer was examined in Cox proportional hazards analysis.

RESULTS

During a mean follow-up of 15.5 years, 9487 cases of invasive breast cancer were identified. Total Se (highest versus lowest quartile: HR 1.00, 95% CI 0.92-1.09, P_trend = 0.66), dietary Se (highest versus lowest quartile: HR 0.99, 95% CI 0.89-1.08, P_trend = 0.61), and supplemental Se (yes versus no: HR 0.99, 95% CI 0.95-1.03) were not associated with breast cancer incidence.

CONCLUSIONS

This study indicates that Se intake is not associated with incident breast cancer among postmenopausal women in the United States. Further studies are needed to confirm our findings by using biomarkers such as toenail Se to reduce the potential for misclassification of Se status.

Double-detecting fluorescent sensor for ATP based on Cu2+ and Zn2+ response of hydrazono-bis-tetraphenylethylene

Although all kinds of sensors with unique detecting ability for one guest were reported, the fluorescence sensor with multiple detecting abilities was seldom presented. This work designed and synthesized a novel AIE fluorescence probe bearing double detecting for ATP based on Cu²⁺ and Zn²⁺ response of hydrazono-bis-tetraphenylethylene (Bis-TPE). Bis-TPE was prepared in 82% yield with simple procedure. It exhibited strong red AIE fluorescence based on the large conjugated electron effect in aqueous media. It showed outstanding selective sensing abilities for Cu²⁺ by strong fluorescence quenching and for Zn²⁺ by red-orange fluorescence change. The sensing mechanism of 1:1 stoichiometric ratios was confirmed by ¹H NMR and MS study. The strong red fluorescence of Bis-TPE + Cu²⁺ system could be recovered by adding ATP. The orange fluorescence of Bis-TPE + Zn²⁺ system could be quenched by adding Cu²⁺ and then was recovered by adding ATP. These double detecting abilities for ATP with the "off-on" red fluorescence in Bis-TPE + Cu²⁺ system and "allochroic-off-on" orange fluorescence in Bis-TPE + Zn²⁺+Cu²⁺ system were successfully applied to test Cu²⁺, Zn²⁺ and ATP in test paper and living cell imaging, displaying the good application prospects for sensing Cu²⁺, Zn²⁺ and double detecting ATP in the complicated environment.

Zinc dysregulation in cancers and its potential as a therapeutic target

Zinc is an essential element and serves as a structural or catalytic component in many proteins. Two families of transporters are involved in maintaining cellular zinc homeostasis: the ZIP (SLC39A) family that facilitates zinc influx into the cytoplasm, and the ZnT (SLC30A) family that facilitates zinc efflux from the cytoplasm. Zinc dyshomeostasis caused by the dysfunction of zinc transporters can contribute to the initiation or progression of various cancers, including prostate cancer, breast cancer, and pancreatic cancer. In addition, intracellular zinc fluctuations lead to the disturbance of certain signaling pathways involved in the malignant properties of cancer cells. This review briefly summarizes our current understanding of zinc dyshomeostasis in cancer, and discusses the potential roles of zinc or zinc transporters in cancer therapy.

MicroRNAs Involved in Metastasis of Hepatocellular Carcinoma: Target Candidates, Functionality and Efficacy in Animal Models and Prognostic Relevance

Hepatocellular carcinoma (HCC) is responsible for the second-leading cancer-related death toll worldwide. Although sorafenib and levantinib as frontline therapy and regorafenib, cabazantinib and ramicurimab have now been approved for second-line therapy, the therapeutic benefit is in the range of only a few months with respect to prolongation of survival. Aggressiveness of HCC is mediated by metastasis. Intrahepatic metastases and distant metastasis to the lungs, lymph nodes, bones, omentum, adrenal gland and brain have been observed. Therefore, the identification of metastasis-related new targets and treatment modalities is of paramount importance. In this review, we focus on metastasis-related microRNAs (miRs) as therapeutic targets for HCC. We describe miRs which mediate or repress HCC metastasis in mouse xenograft models. We discuss 18 metastasis-promoting miRs and 35 metastasis-inhibiting miRs according to the criteria as outlined. Six of the metastasis-promoting miRs (miR-29a, -219-5p, -331-3p, 425-5p, -487a and -1247-3p) are associated with unfavourable clinical prognosis. Another set of six down-regulated miRs (miR-101, -129-3p, -137, -149, -503, and -630) correlate with a worse clinical prognosis. We discuss the corresponding metastasis-related targets as well as their potential as therapeutic modalities for treatment of HCC-related metastasis. A subset of up-regulated miRs -29a, -219-5p and -425-5p and down-regulated miRs -129-3p and -630 were evaluated in orthotopic metastasis-related models which are suitable to mimic HCC-related metastasis. Those miRNAs may represent prioritized targets emerging from our survey.

Dietary zinc deficiency or supplementation during gestation increases breast cancer susceptibility in adult female mice offspring following a J-shaped pattern and through distinct mechanisms

Zinc is required for fetal development and is involved in key processes associated with breast carcinogenesis. We evaluated whether maternal zinc deficiency or supplementation during gestation influences female offspring susceptibility to breast cancer in adulthood. C57BL/6 mice consumed during gestation control (30 p.p.m. zinc), zinc-deficient (8 p.p.m) or zinc-supplemented (45 p.p.m.) diets. Maternal zinc supplementation increased in female mice offspring the incidence of chemically-induced mammary adenocarcinomas that were heavier, compared to control group. This was accompanied by a decreased number of terminal end buds, increased cell proliferation and apoptosis, and increased tumor suppressors p21, p53 and Rassf1, Zfp382 and Stat3 expression in mammary glands, as well as increased zinc status. Although maternal zinc deficiency did not alter the incidence of these lesions, it also induced heavier mammary adenocarcinomas, compared to control group. These effects were accompanied by a decreased number of terminal end buds, increased proto-oncogenes c-Myc and Lmo4 expression and H3K9Me3 and H4K20Me3 epigenetic marks in mammary glands of offspring, and decreased zinc status and increased levels of oxidative marker malondialdehyde. The data suggest that both maternal zinc deficiency and supplementation during gestation programmed increased breast cancer susceptibility in adult mice offspring following a J-shaped pattern through distinct mechanisms.

Recombinant Expression of Zinc Transporter SLC39A6 and Its Functional Antibody Production

Zinc transporter ZIP6 (SLC39A6) or LIV-1 is a protein that belongs to a subfamily of proteins group that displays structural specifications of zinc transporters in the cell membrane. Overexpression of this protein is observed in breast, prostate, and kidney tumor cells. Lately, LIV-1 is a dependable marker for detection of estrogen receptor positive breast cancer, which can be used to detect luminal breast cancer type A. In this study, the gene construct containing extracellular domain of human LIV-1 gene was subcloned into pET22b expression vector, expressed and confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and western blotting. It was shown for the first time that the extracellular domain of LIV-1 could be expressed in bacterial systems and can be used for rabbit immunization. The reactivity of the resulted antibody was evaluated in flow cytometry and enzyme-linked immunosorbent assay. In conclusion, this protein can be used for animal immunization toward preparation of a new monoclonal antibody that can be introduced as a drug in the treatment of breast cancer.

Cysteine-rich intestinal protein 1 silencing alleviates the migration and invasive capability enhancement induced by excessive zinc supplementation in colorectal cancer cells

Cysteine-rich intestinal protein 1 (CRIP1) is overexpressed in colorectal cancer (CRC) tissues and functions as an oncogene in regulating the migration and invasion of CRC cells. However, the underlying mechanism is unclear. CRIP1 has a role in zinc absorption and functions as an intracellular zinc transport protein. Here, we aimed to focus on the function of zinc and its underlying mechanism in CRC and determine whether CRIP1 promotes invasion and CRC metastasis through excessive zinc-induced epithelial-mesenchymal transition (EMT) by affecting the phosphorylated glycogen synthase kinase (GSK)-3beta. The results showed that ZnSO₄ (Zn²⁺) supplementation in medium increased the labile intracellular zinc content. Furthermore, excessive Zn²⁺ supplementation activated the GSK3/mTOR signaling pathway in both SW620 and LoVo cells, and excessive Zn²⁺ supplementation promoted migration, invasion, and EMT of SW620 and LoVo cells. This migration promotion was alleviated by the specific mTOR inhibitor rapamycin, indicating that the GSK3/mTOR signaling pathway was involved in this process. CRIP1 silencing increased the labile intracellular zinc content and inhibited EMT and GSK3/mTOR signaling pathway. CRIP1 silencing alleviated the zinc supplementation effects on migration, invasion, EMT, and GSK3/mTOR signaling pathway. In conclusion, excessive Zn²⁺ promotes migration and invasion capabilities of SW620 and LoVo cells through GSK3/mTOR signaling pathway-induced EMT.

Association between serum zinc levels and lung cancer: a meta-analysis of observational studies

BACKGROUND

Inconsistent results according to numerous studies that had investigated the association between serum zinc levels and lung cancer risk were reported. The aim of this study was to explore whether serum zinc levels were lower in lung cancer patients than that in controls.

METHODS

We systematically retrieved the databases of PubMed, Wanfang, Cochrane, ScienceDirect website, CNKI, and SinoMed databases for comprehensive relevant studies published before December 2018 and conducted a meta-analysis. Standard mean differences (SMD) were pooled using a random effects model.

RESULTS

Thirty-two articles were eligible to investigate the correlation between serum zinc levels and lung cancer risk, involving 2894 cases and 9419 controls. The pooled results showed sufficient evidence approving the association between serum zinc levels and lung cancer risk. And the serum zinc levels in lung cancer were significantly lower than that in controls (summary SMD = - 0.88, 95% confidence interval (CI) = - 0.94, - 0.82). Meanwhile, consistent results were obtained both in European populations and Asian populations. No publication bias was detected in our analysis.

CONCLUSIONS

The present meta-analysis suggested that serum zinc levels were significantly lower in lung cancer patients than that in controls.

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.