Selenium and lung cancer: a systematic review and meta analysis

Effects of Antioxidant Dietary Supplement Use upon Response to Cancer Treatment: A Scoping Review of Available Evidence

INTRODUCTION

The effects of antioxidant dietary supplements on response to biological therapies for cancer is unknown. We conducted a scoping review of the available systematic review evidence on this question.

METHODS AND ANALYSIS

We searched six databases from inception to August 19, 2022 for systematic reviews of randomized controlled trials of antioxidant dietary supplements used by patients receiving curative chemotherapy, radiotherapy, or other biological therapy for cancer and assessing the impact of supplements on survival, treatment response, or disease progression. We focused on results from reviews at high or moderate AMSTAR-2 quality. Records were selected, data extracted, and AMSTAR-2 ratings assessed independently by two authors.

RESULTS

We found 24 systematic reviews with relevant evidence. Reviews were heterogenous in cancers, treatments, and antioxidant dietary supplements assessed. Conclusions across reviews were mixed, ranging from negative to no apparent difference to positive, but always with caveats about the limited size and quality of the evidence. One review was rated 'moderate' on AMSTAR-2; it included one small trial of vitamin C and formed no firm conclusions.

CONCLUSIONS

We did not find reliable systematic review evidence on the effects of antioxidant dietary supplements upon therapies for cancer. More research is necessary to inform clinical recommendations.

In vitro assessment of the effect of magnetic fields on efficacy of biosynthesized selenium nanoparticles by Alborzia kermanshahica

Cyanobacteria represent a rich resource of a wide array of unique bioactive compounds that are proving to be potent sources of anticancer drugs. Selenium nanoparticles (SeNPs) have shown an increasing potential as major therapeutic platforms and led to the production of higher levels of ROS that can present desirable anticancer properties. Chitosan-SeNPs have also presented antitumor properties against hepatic cancer cell lines, especially the Cht-NP (Chitosan-NPs), promoting ROS generation and mitochondria dysfunction. It is proposed that magnetic fields can add new dimensions to nanoparticle applications. Hence, in this study, the biosynthesis of SeNPs using Alborzia kermanshahica and chitosan (CS) as stabilizers has been developed. The SeNPs synthesis was performed at different cyanobacterial cultivation conditions, including control (without magnetic field) and magnetic fields of 30 mT and 60 mT. The SeNPs were characterized by uv-visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), Dynamic light scattering (DLS), zeta potential, and TEM. In addition, the antibacterial activity, inhibition of bacterial growth, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC), as well as the antifungal activity and cytotoxicity of SeNPs, were performed. The results of uv-visible spectrometry, DLS, and zeta potential showed that 60 mT had the highest value regarding the adsorption, size, and stabilization in compared to the control. FTIR spectroscopy results showed consistent spectra, but the increased intensity of peaks indicates an increase in bond number after exposure to 30 mT and 60 mT. The results of the antibacterial activity and the inhibition zone diameter of synthesized nanoparticles showed that Staphylococcus aureus was more sensitive to nanoparticles produced under 60 mT. Se-NPs produced by Alborzia kermanshahica cultured under a 60 mT magnetic field exhibit potent antimicrobial and anticancer properties, making them a promising natural agent for use in the pharmaceutical and biomedical industries.

Bis(1-methylimidazol-2-yl) diselenide and its evaluation as a chemical radio-protector: role of kinetic rate constants for ROS scavenging and glutathione peroxidase like activity

Bis(1-methylimidazol-2-yl) diselenide (MeImSe), a derivative of selenoneine, has been examined for bimolecular rate constants for scavenging of various radiolytically and non-radiolytically generated reactive oxygen species (ROS). Further, its potential to show glutathione peroxidase (GPx)-like activity and to protect in vitro models of DNA and lipid against radiation induced strand breakage and lipid peroxidation, respectively were studied. The results confirmed that MeImSe scavenged all major short-lived (hydroxyl radical) and long-lived (peroxyl radical, carbonate radical, nitrogen dioxide radical, hypochlorite and hydrogen peroxide) oxidants involved in the radiation toxicity either directly or through GPx-like catalytic mechanism. The rate constants of MeImSe for these oxidants were found to be comparable to analogous sulfur and selenium-based compounds. The enzyme kinetics study established that MeImSe took part in the GPx cycle through the reductive pathway. Further, MeImSe inhibited the radiation induced DNA strand cleavage and lipid peroxidation with half maximal inhibitory concentration (IC50) of ∼ 60 μM and ∼100 μM, respectively. Interestingly, MeImSe treatment in the above concentration range (>100 μM) did not show any significant toxicity in normal human lung fibroblast (WI26) cells. The balance between efficacy and toxicity of MeImSe as a chemical radioprotector was attributed to the formation of less reactive intermediates during its oxidation/reduction reactions as evidenced from NMR studies.HighlightsMeImSe, a derivative of selenoneine protects DNA and lipid from radiation damageMeImSe scavenges all major short- and long-lived oxidants involved in radiation toxicityRate constants of MeImSe for ROS scavenging determined by pulse radiolysis techniqueFirst organoselenium compound reported to scavenge nitrogen dioxide radicalMeImSe exhibits GPx-like activity through reductive pathway.

Theranostic applications of selenium nanomedicines against lung cancer

The incidence and mortality rates of lung cancer are among the highest in the world. Traditional treatment methods include surgery, chemotherapy, and radiotherapy. Although rapid progress has been achieved in the past decade, treatment limitations remain. It is therefore imperative to identify safer and more effective therapeutic methods, and research is currently being conducted to identify more efficient and less harmful drugs. In recent years, the discovery of antitumor drugs based on the essential trace element selenium (Se) has provided good prospects for lung cancer treatments. In particular, compared to inorganic Se (Inorg-Se) and organic Se (Org-Se), Se nanomedicine (Se nanoparticles; SeNPs) shows much higher bioavailability and antioxidant activity and lower toxicity. SeNPs can also be used as a drug delivery carrier to better regulate protein and DNA biosynthesis and protein kinase C activity, thus playing a role in inhibiting cancer cell proliferation. SeNPs can also effectively activate antigen-presenting cells to stimulate cell immunity, exert regulatory effects on innate and regulatory immunity, and enhance lung cancer immunotherapy. This review summarizes the application of Se-based species and materials in lung cancer diagnosis, including fluorescence, MR, CT, photoacoustic imaging and other diagnostic methods, as well as treatments, including direct killing, radiosensitization, chemotherapeutic sensitization, photothermodynamics, and enhanced immunotherapy. In addition, the application prospects and challenges of Se-based drugs in lung cancer are examined, as well as their forecasted future clinical applications and sustainable development.

An Assessment of Serum Selenium Concentration in Women with Ovarian Cancer

BACKGROUND

Available studies on the effect of serum selenium levels on the risk of malignancies show some conflicting results. In this study, we investigated the correlation between serum selenium levels and ovarian cancer occurrence.

METHODS

314 women (157 diseased patients and 157 healthy ones) matched in terms of age and BMI were included in the study. The measurements of selenium in the collected blood samples were performed using an ICP mass spectrometer. Univariable and multivariable analyzes were performed to determine the relationship between the factors under the study and the occurrence of ovarian cancer.

RESULTS

The mean concentration of selenium was lower among diseased ones than among controls (53.31 μg/L vs. 78.99 μg/L). A decrease in selenium concentration was noticed with the advancement of ovarian cancer. In univariable and multivariable analyzes, a clear relationship between low selenium concentration and the occurrence of ovarian cancer was found (35.3 (95% CI: 11.2-111; p < 0.001) and 45.8 (95% CI: 12.8-164; p < 0.001)).

CONCLUSION

The studied patients with ovarian cancer are characterized by statistically significant lower serum selenium levels than patients from the control group. Among the study group, a decrease in selenium concentration was observed with an increase in the FIGO stage. The determination of the role of selenium as a prophylactic factor in ovarian cancer requires further prospective studies.

Association between Dietary and Supplemental Antioxidants Intake and Lung Cancer Risk: Evidence from a Cancer Screening Trial

Previous studies provided inconsistent results on the effects of antioxidant nutrient intake on lung cancer prevention. We aimed to evaluate the association between antioxidant consumption from food and supplemental sources and lung cancer incidence. Data were obtained from the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial. A total of 98,451 participants were included in the data analysis. We used a multivariable Cox proportional hazards regression model to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between antioxidant intake and lung cancer risk. Dose-response assessments for individual nutrients were conducted. We also selected the model for the best combination of antioxidants for reducing lung cancer risk using machine learning methods. After the median follow-up of 12.2 years, 1642 new cases were identified. Intake of the calculated HRs indicated a trend for a higher quartile of food-based Composite Dietary Antioxidant Index (fCDAI) associated with a lower lung cancer risk after adjusting for covariates (HR_Q4vs.Q1 = 0.64, 95% CI: 0.52, 0.79; P for trend < 0.001). Protective effects of dietary antioxidant intake were observed across all individual antioxidant micronutrients except magnesium. Random forests model suggested the dietary intake group of α-carotene, magnesium, vitamin C, vitamin E, lycopene, selenium, lutein, and zeaxanthin, and β-carotene had the most favorable effects on lung cancer prevention. Higher consumption of antioxidants from food sources has a protective effect against lung cancer, while no effects were shown in the supplemental group. It is recommended to consume a combination of various antioxidants due to the potential benefits from the interaction, while more research should be performed to investigate the underlying mechanisms of antioxidant synergic effects on lung cancer risk reduction.

Druggable Biomarkers Altered in Clear Cell Renal Cell Carcinoma: Strategy for the Development of Mechanism-Based Combination Therapy

Targeted therapeutics made significant advances in the treatment of patients with advanced clear cell renal cell carcinoma (ccRCC). Resistance and serious adverse events associated with standard therapy of patients with advanced ccRCC highlight the need to identify alternative 'druggable' targets to those currently under clinical development. Although the Von Hippel-Lindau (VHL) and Polybromo1 (PBRM1) tumor-suppressor genes are the two most frequently mutated genes and represent the hallmark of the ccRCC phenotype, stable expression of hypoxia-inducible factor-1α/2α (HIFs), microRNAs-210 and -155 (miR_S), transforming growth factor-beta (TGF-ß), nuclear factor erythroid 2-related factor 2 (Nrf2), and thymidine phosphorylase (TP) are targets overexpressed in the majority of ccRCC tumors. Collectively, these altered biomarkers are highly interactive and are considered master regulators of processes implicated in increased tumor angiogenesis, metastasis, drug resistance, and immune evasion. In recognition of the therapeutic potential of the indicated biomarkers, considerable efforts are underway to develop therapeutically effective and selective inhibitors of individual targets. It was demonstrated that HIF_S, miR_S, Nrf2, and TGF-ß are targeted by a defined dose and schedule of a specific type of selenium-containing molecules, seleno-L-methionine (SLM) and methylselenocystein (MSC). Collectively, the demonstrated pleiotropic effects of selenium were associated with the normalization of tumor vasculature, and enhanced drug delivery and distribution to tumor tissue, resulting in enhanced efficacy of multiple chemotherapeutic drugs and biologically targeted molecules. Higher selenium doses than those used in clinical prevention trials inhibit multiple targets altered in ccRCC tumors, which could offer the potential for the development of a new and novel therapeutic modality for cancer patients with similar selenium target expression. Better understanding of the underlying mechanisms of selenium modulation of specific targets altered in ccRCC could potentially have a significant impact on the development of a more efficacious and selective mechanism-based combination for the treatment of patients with cancer.

Investigating Causal Associations of Circulating Micronutrients Concentrations with the Risk of Lung Cancer: A Mendelian Randomization Study

Previous observational studies have suggested that the effect of diet-derived circulating micronutrient concentrations on lung cancer (LC) risk is controversial. We conducted a two-sample Mendelian randomization (MR) analysis to investigate the causal relationship between circulating micronutrient concentrations and the overall risk of LC and three LC subtypes (namely lung adenocarcinoma (LA), squamous cell lung cancer (SqCLC), and small cell lung cancer (SCLC)). The instrumental variables (IVs) of 11 micronutrients (beta-carotene, calcium, copper, folate, lycopene, magnesium, phosphorus, retinol, selenium, zinc, and vitamin B6) were screened from the published genome-wide association studies (GWAS). Summary statistics related to LC and its subtypes came from the largest meta-analysis, including 29,266 cases and 56,450 controls. Inverse-variance weighted (IVW) method is used as the main MR analysis, and the sensitivity analysis is carried out to ensure the MR assumptions. This MR study found suggestive evidence that genetically predicted 6 circulating micronutrient concentrations was correlated with the risk of overall LC (odds ratio (OR): 1.394, 95% confidence interval (CI): 1.041–1.868, p = 0.026, phosphorus), LA (OR: 0.794, 95% CI: 0.634–0.995, p = 0.045, beta-carotene; OR: 0.687, 95%CI: 0.494–0.957, p = 0.026, calcium), SqCLC (OR: 0.354, 95% CI: 0.145–0.865, p = 0.023, retinol), and SCLC (OR: 1.267, 95% CI: 1.040–1.543, p = 0.019, copper; OR: 0.801, 95% CI: 0.679–0.944, p = 0.008, zinc). We found no evidence that other micronutrients are associated with the risk of overall LC or its subtypes. Our study suggested that the increase in circulating beta-carotene, calcium, retinol, and zinc concentration may reduce the risk of LC; the increase in circulating copper and phosphorus concentration may be related to the increased risk of LC. In the future, larger replication samples of LC genetic data and larger micronutrient-related GWAS will be needed to verify our findings.

Selenium Yeast and Fish Oil Combination Diminishes Cancer Stem Cell Traits and Reverses Cisplatin Resistance in A549 Sphere Cells

Cisplatin is a prevalent chemotherapeutic agent used for non-small cell lung cancer (NSCLC) that is difficult to treat by targeted therapy, but the emergence of resistance severely limits its efficacy. Thus, an effective strategy to combat cisplatin resistance is required. This study demonstrated that, at clinically achievable concentrations, the combination of selenium yeast (Se-Y) and fish oil (FO) could synergistically induce the apoptosis of cancer stem cell (CSC)-like A549 NSCLC sphere cells, accompanied by a reversal of their resistance to cisplatin. Compared to parental A549 cells, sphere cells have higher cisplatin resistance and possess elevated CSC markers (CD133 and ABCG2), epithelial-mesenchymal transition markers (anexelekto (AXL), vimentin, and N-cadherin), and cytoprotective endoplasmic reticulum (ER) stress marker (glucose-regulated protein 78) and increased oncogenic drivers, such as yes-associated protein, transcriptional coactivator with PDZ-binding motif, β-catenin, and cyclooxygenase-2. In contrast, the proapoptotic ER stress marker CCAAT/enhancer-binding protein homologous protein and AMP-activated protein kinase (AMPK) activity were reduced in sphere cells. The Se-Y and FO combination synergistically counteracted the above molecular features of A549 sphere cells and diminished their elevated CSC-like side population. AMPK inhibition by compound C restored the side population proportion diminished by this nutrient combination. The results suggest that the Se-Y and FO combination can potentially improve the outcome of cisplatin-treated NSCLC with phenotypes such as A549 cells.

Inhibiting Metastasis and Improving Chemosensitivity via Chitosan-Coated Selenium Nanoparticles for Brain Cancer Therapy

Selenium nanoparticles (SeNPs) were synthesized to overcome the limitations of selenium, such as its narrow safe range and low water solubility. SeNPs reduce the toxicity and improve the bioavailability of selenium. Chitosan-coated SeNPs (Cs-SeNPs) were developed to further stabilize SeNPs and to test their effects against glioma cells. The effects of Cs-SeNPs on cell growth were evaluated in monolayer and 3D-tumor spheroid culture. Cell migration and cell invasion were determined using a trans-well assay. The effect of Cs-SeNPs on chemotherapeutic drug 5-fluorouracil (5-FU) sensitivity of glioma cells was determined in tumor spheroids. An in vitro blood–brain barrier (BBB) model was established to test the permeability of Cs-SeNPs. SeNPs and Cs-SeNPs can reduce the cell viability of glioma cells in a dose-dependent manner. Compared with SeNPs, Cs-SeNPs more strongly inhibited 3D-tumor spheroid growth. Cs-SeNPs exhibited stronger effects in inhibiting cell migration and cell invasion than SeNPs. Improved 5-FU sensitivity was observed in Cs-SeNP-treated cells. Cellular uptake in glioma cells indicated a higher uptake rate of coumarin-6-labeled Cs-SeNPs than SeNPs. The capability of coumarin-6 associated Cs-SeNPs to pass through the BBB was confirmed. Taken together, Cs-SeNPs provide exceptional performance and are a potential alternative therapeutic strategy for future glioma treatment.

Biomarkers of disease in human nails: a comprehensive review

Diagnostic, monitoring, response, predictive, risk, and prognostic biomarkers of disease are all widely studied, for the most part in biological fluids or tissues, but there is steadily growing interest in alternative matrices such as nails. Here we comprehensively review studies dealing with molecular or elemental biomarkers of disease, as opposed to semiological, pharmacological, toxicological, or biomonitoring studies. Nails have a long history of use in medicine as indicators of pathological processes and have also been used extensively as a matrix for monitoring exposure to environmental pollution. Nail clippings are simple to collect noninvasively as well as to transport and store, and the matrix itself is relatively stable. Nails incorporate, and are influenced by, circulating molecules and elements over their several months of growth, and it is widely held that markers of biological processes will remain in the nail, even when their levels in blood have declined. Nails thus offer the possibility to not only look back into a subject's metabolic history but also to study biomarkers of processes that operate over a longer time scale such as the post-translational modification of proteins. Reports on ungual biomarkers of metabolic and endocrine diseases, cancer, and psychological and neurological disorders will be presented, and an overview of the sampling and analytical techniques provided.

Zinc and Selenium in Inflammatory Bowel Disease: Trace Elements with Key Roles?

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that may emerge at a young age and often lasts for life. It often goes through phases of recurrence and remission and has a devastating effect on quality of life. The exact etiology of the disease is still unclear, but it appears that an inappropriate immune response to intestinal flora bacteria in people with a genetic predisposition may cause the disease. Managing inflammatory bowel disease is still a serious challenge. Oxidative stress and free radicals appear to be involved in the pathogenesis of this disease, and a number of studies have suggested the use of antioxidants as a therapeutic approach. The antioxidant and anti-inflammatory properties of some trace elements have led some of the research to focus on studying these trace elements in inflammatory bowel disease. Zinc and selenium are among the most important trace elements that have significant anti-inflammatory and antioxidant properties. Some studies have shown the importance of these trace elements in inflammatory bowel disease. In this review, we have attempted to provide a comprehensive overview of the findings of these studies and to gather current knowledge about the association of these trace elements with the inflammatory process and inflammatory bowel disease.

Selenium as a Bioactive Micronutrient in the Human Diet and Its Cancer Chemopreventive Activity

This review answers the question of why selenium is such an important trace element in the human diet. Daily dietary intake of selenium and its content in various food products is discussed in this paper, as well as the effects of its deficiency and excess in the body. Moreover, the biological activity of selenium, which it performs mainly through selenoproteins, is discussed. These specific proteins are responsible for thyroid hormone management, fertility, the aging process, and immunity, but their key role is to maintain a redox balance in cells. Furthermore, taking into account world news and the current SARS-CoV-2 virus pandemic, the impact of selenium on the course of COVID-19 is also discussed. Another worldwide problem is the number of new cancer cases and cancer-related mortality. Thus, the last part of the article discusses the impact of selenium on cancer risk based on clinical trials (including NPC and SELECT), systematic reviews, and meta-analyses. Additionally, this review discusses the possible mechanisms of selenium action that prevent cancer development.

Assessing the Current State of Lung Cancer Chemoprevention: A Comprehensive Overview

Chemoprevention of lung cancer is thought to significantly reduce the risk of acquiring these conditions in the subpopulation of patients with underlying health issues, such as chronic obstructive pulmonary disorder and smoking-associated lung problems. Many strategies have been tested in the previous decades, with very few translating to successful clinical trials in specific subpopulations of patients. In this review, we analyze these strategies, as well as new approaches that have emerged throughout the last few years, including synthetic lethality concept and microbiome-induced regulation of lung carcinogenesis. Overall, the continuous effort in the area of lung chemoprevention is required to develop practical therapeutical approaches. Given the inconsistency of results obtained in clinical trials targeting lung cancer chemoprevention in various subgroups of patients that differ in the underlying health condition, race, and gender, we believe that individualized approaches will have more promise than generalized treatments.

Drugs for preventing lung cancer in healthy people

BACKGROUND

This is the second update of this Cochrane Review. Some studies have suggested a protective effect of antioxidant nutrients and higher dietary levels of fruits and vegetables on lung cancer.

OBJECTIVES

To determine whether vitamins and minerals and other potential agents, alone or in combination, reduce lung cancer incidence and lung cancer mortality in healthy populations.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase from 1974 to May 2019 and screened references included in published studies and reviews.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing vitamins or mineral supplements with placebo, administered to healthy people with the aim of preventing lung cancer.

DATA COLLECTION AND ANALYSIS

Four review authors independently selected the trials to be included in the review, assessed their methodological quality and extracted data. For dichotomous outcomes we calculated risk ratios (RRs) and 95% confidence intervals (CIs) and pooled results using the random-effects model. We assessed the risk of bias using Cochrane's 'Risk of bias' assessment tool and certainty of evidence using the GRADE approach.

MAIN RESULTS

In this update, we identified three new trials for a total of 12 studies. Six analysed vitamin A, three vitamin C, three combined vitamin D3 + calcium, four vitamin E combined with other products, one selenium supplements and nine studied combinations of two or more products. Four studies included only men and five only women. Vitamin A results in little to no difference in lung cancer incidence (RR 1.09, 95% CI 1.00 to 1.19; 5 RCTs, 212314 participants; high-certainty evidence) and lung cancer mortality (RR 1.06, 95% CI 0.81 to 1.38; 3 RCTs, 190118 participants; high-certainty evidence). But in smokers or asbestos workers vitamin A increases the risk of lung cancer incidence (RR 1.10, 95% CI 1.01 to 1.20; 3 RCTs, 43995 participants; high-certainty evidence), lung cancer mortality (RR 1.18, 95% CI 1.01 to 1.38; 2 RCTs, 29426 participants; high-certainty evidence) and all-cause mortality (RR 1.09, 95% CI 1.05 to 1.13; 2 RCTs, 32883 participants; high-certainty evidence). Vitamin A increases the risk of minor side effects, such as yellowing of the skin and minor gastrointestinal symptoms (high-certainty evidence). Vitamin C likely results in little to no difference in lung cancer incidence (RR 1.29, 95% CI 0.67 to 2.49; 2 RCTs, 14953 participants; moderate-certainty evidence). In women, vitamin C increases the risk of lung cancer incidence (RR 1.84, 95% CI 1.14 to 2.95; 1 RCT, 7627 participants; high-certainty evidence). In men, vitamin C results in little to no difference in mortality for lung cancer (RR 0.81, 95% CI 0.53 to 1.23; 1 RCT, 7326 participants; high-certainty evidence). Vitamin D + calcium may result in little to no difference in lung cancer incidence in postmenopausal women (RR 0.90, 95% CI 0.39 to 2.08; 3 RCTs, 37601 women; low-certainty evidence). Vitamin E results in little to no difference in lung cancer incidence (RR 1.01, 95% CI 0.90 to 1.14; 3 RCTs, 36841 participants; high-certainty evidence) or to lung cancer mortality (RR 0.96, 95% CI 0.77 to 1.18; 2 RCTs, 29214 participants; high-certainty evidence), but increases the risk of haemorrhagic strokes (hazard ratio (HR), 1.74, 95% CI 1.04 to 2.91; 1 RCT, 14641 participants; high-certainty evidence). Calcium results in little to no difference in lung cancer incidence in postmenopausal women (RR 0.65, 95% CI 0.13 to 3.18; 1 RCT, 733 participants) or in risk of renal calculi (RR 1.94, 95% CI 0.20 to 18.57; 1 RCT, 733 participants; low-certainty evidence). Selenium in men results in little to no difference in lung cancer incidence (RR 1.11, 95% CI 0.80 to 1.54; 1 RCT, 17448 participants; high-certainty evidence) and lung cancer mortality (RR 1.09, 95% CI 0.72 to 1.66; 1 RCT, 17448 participants; high-certainty evidence) and increases the risk for grade 1 to 2 dermatitis (RR 1.16, 95% CI 1.04 to 1.31; 1 RCT, 17448 participants; high-certainty evidence) and for alopecia (RR 1.28, 95% CI 1.07 to 1.53; 1 RCT, 17448 participants; high-certainty evidence). The combination of vitamins A, C, E + selenium + zinc results in little to no difference in lung cancer incidence (RR 0.64, 95% CI 0.28 to 1.48; 1 RCT, 12741 participants; high-certainty evidence).

AUTHORS' CONCLUSIONS

Well-designed RCTs have shown no beneficial effect of supplements for the prevention of lung cancer and lung cancer mortality in healthy people. Vitamin A supplements increase lung cancer incidence and mortality in smokers or persons exposed to asbestos. Vitamin C increases lung cancer incidence in women. Vitamin E increases the risk of haemorrhagic strokes.

Association of various dietary habits and risk of lung cancer: an updated comprehensive literature review

Lung cancer remains the leading cause of cancer death in both men and women worldwide. Tobacco smoking remains the single most important factor. Recent research has focused on the role of nutrition and dietary habits on lung tumorigenesis. With many individual reports on separate dietary aspects, no single review is available in the literature that summarizes the updated studies. To our knowledge, this is the first review that comprehensively reviews the updated literature on the effect of dietary habits on lung cancer. This review was concluded in February 2019 and included all meta-analyses, systematic reviews, and literature reviews. Thirty studies were retrieved in total. Items in the diet that offer a protective effect on lung parenchyma are fruits, vegetables, fish, nuts, soy, B vitamins, vitamin D, vitamin E, vitamin C, and zinc. Changing dietary habits to decrease the risk of lung cancer can be performed in parallel with smoking cessation programs. There is a need for future studies with large sample sizes to accurately evaluate some aspects of nutrition and their effect on lung cancer risk. Physicians are encouraged to provide nutritional advice to their patients.

Strategies for the development of selenium-based anticancer drugs

Many experimental models demonstrated that inorganic and organic selenium (Se) compounds may have an anticancer activity. However, large clinical studies failed to demonstrate that Se supplementations may prevent the outcome of cancers. Moreover, there are few randomized trials in cancer patients and there is not yet any Se compound recognized as anticancer drug. There is still a need to develop new Se compounds with new strategies. For that, it may be necessary to consider that Se compounds may have a dual role, either as anti-oxidant or as pro-oxidant. Experimental studies demonstrated that it is as pro-oxidant that Se compounds have anticancer effects, even though cancer cells have a pro-oxidant status. The oxidative status differs according to the type of cancer, the stage of the disease and to other parameters. We propose to adapt the doses of the Se compounds to markers of the oxidative stress, but also to markers of angiogenesis, which is strongly related with the oxidative status. A dual role of Se on angiogenesis has also been noted, either as pro-angiogenesis or as anti-angiogenesis. The objective for the development of new Se compounds, having a great selectivity on cancer cells, could be to try to normalize these oxidative and angiogenic markers in cancer patients, with an individual adaptation of doses.

Opposite Regulation of CHOP and GRP78 and Synergistic Apoptosis Induction by Selenium Yeast and Fish Oil via AMPK Activation in Lung Adenocarcinoma Cells

Selenium has been intensively studied for the use of cancer prevention and treatment. However, the clinical effects are still plausible. To enhance its efficacy, a combinational study of selenium yeast (SY) and fish oil (FO) was performed in A549, CL1-0, H1299, HCC827 lung adenocarcinoma (LADC) cells to investigate the enhancement in apoptosis induction and underlying mechanism. By sulforhodamine B staining, Western blot and flow cytometric assays, we found a synergism between SY and FO in growth inhibition and apoptosis induction of LADC cells. In contrast, the fetal lung fibroblast cells (MRC-5) were unsusceptible to this combination effect. FO synergized SY-induced apoptosis of A549 cells, accompanied with synergistic activation of AMP-activated protein kinase (AMPK) and reduction of Cyclooxygenase (COX)-2 and β-catenin. Particularly, combining with FO not only enhanced the SY-elevated proapoptotic endoplasmic reticulum (ER) stress marker CCAAT/enhancer-binding protein homologous protein (CHOP), but also reduced the cytoprotective glucose regulated protein of molecular weight 78 kDa (GRP78). Consequently, the CHOP downstream targets such as phospho-JNK and death receptor 5 were also elevated, along with the cleavage of caspase-8, -3, and the ER stress-related caspase-4. Accordingly, inhibition of AMPK by compound C diminished the synergistic apoptosis induction, and elevated CHOP/GRP78 ratio by SY combined with FO. The AMPK-dependent synergism suggests the combination of SY and FO for chemoprevention and integrative treatment of LADC.

Tumor Suppressor Activity of Selenbp1, a Direct Nkx2-1 Target, in Lung Adenocarcinoma

The Nkx2-1 transcription factor promotes differentiation of lung epithelial lineages and suppresses malignant progression of lung adenocarcinoma. However, targets of Nkx2-1 that limit tumor growth and progression remain incompletely understood. Here, direct Nkx2-1 targets are identified whose expression correlates with Nkx2-1 activity in human lung adenocarcinoma. Selenium-binding protein 1 (Selenbp1), an Nkx2-1 effector that limits phenotypes associated with lung cancer growth and metastasis, was investigated further. Loss- and gain-of-function approaches demonstrate that Nkx2-1 is required and sufficient for Selenbp1 expression in lung adenocarcinoma cells. Interestingly, Selenbp1 knockdown also reduced Nkx2-1 expression and Selenbp1 stabilized Nkx2-1 protein levels in a heterologous system, suggesting that these genes function in a positive feedback loop. Selenbp1 inhibits clonal growth and migration and suppresses growth of metastases in an in vivo transplant model. Genetic inactivation of Selenbp1, using CRISPR/Cas9, also enhanced primary tumor growth in autochthonous lung adenocarcinoma mouse models. Collectively, these data demonstrate that Selenbp1 is a direct target of Nkx2-1, which inhibits lung adenocarcinoma growth in vivo Implications: Selenbp1 is an important suppressor of lung tumor growth that functions in a positive feedback loop with Nkx2-1, and whose loss is associated with worse patient outcome. Mol Cancer Res; 16(11); 1737-49. ©2018 AACR.

Serum Paraoxonase, Arylesterase, and Glutathione-S-Transferase Activities and Oxidative Stress Levels in Patients with Mushroom Poisoning

OBJECTIVES

Consumption of toxic species of mushrooms may have detrimental effects and increase oxidative stress. Paraoxonase, arylesterase and glutathione-S-transferase are antioxidants that resist oxidative stress. In this study, we analyzed the changes in these enzymes during intoxication due to mushrooms.

METHODS

The study enrolled 49 adult patients with a diagnosis of mushroom poisoning according to clinical findings and 49 healthy volunteers as the control group. The patients with mild clinical findings were hospitalized due to the possibility that the patient had also eaten the mushrooms and due to clinical findings in the late period, which could be fatal. Paraoxonase, arylesterase, and glutathione-S-transferase concentrations, as well as total antioxidant and oxidant status, were determined in the 49 patients and 49 healthy volunteers by taking blood samples in the emergency department.

RESULTS

While paraoxonase, arylesterase, and total antioxidant status were significantly decreased in the patient group (p<0.05), glutathione-S-transferase, total oxidant status and the oxidative stress index were significantly higher (p<0.05). There was a positive correlation between the hospitalization time and the oxidative stress index (r=0.752, p<0.001), whereas a negative correlation was found with glutathione-S-transferase (r=-0.420, p=0.003).

CONCLUSION

We observed a significant decrease in paraoxonase and arylesterase and an increase in glutathione-S-transferase and oxidative stress indexes in patients with mushroom poisoning, indicating that these patients had an oxidative status. In particular, a low total antioxidant status and high oxidative stress index may gain importance in terms of the assessment of hospitalization duration.

The Ameliorating Effect of Sodium Selenite on the Histological Changes and Expression of Caspase-3 in the Testis of Monosodium Glutamate-Treated Rats: Light and Electron Microscopic Study

Monosodium glutamate (MSG) is a commonly used flavor enhancer that may contribute to male infertility. Sodium selenite is inorganic chemical form of selenium (Se). Se is best known as an antioxidant. This study was designed to investigate the possible ameliorating role of sodium selenite against MSG-induced testicular toxicity and histological changes. Forty male albino rats were allocated into four groups. Control group received distilled water, SE group received sodium selenite (0.25 mg/kg/day) dissolved in distilled water orally, MSG group received MSG (6 mg/g/day) dissolved in distilled water orally, and MSG + SE group received both MSG and sodium selenite for 45 days. Testicular samples were prepared for biochemical, light, and electron microscopic studies. Immunohistochemical staining for caspase-3 was done. MSG group demonstrated a significant increase in malondialdehyde level, marked damage of seminiferous tubules with a significant reduction in diameter and height of the lining epithelium. Spermatogenic cells showed disorganization, dark nuclei, reduction in number, and maturation arrest. Vacuolations of interstitial tissue and Leydig cells were also observed. Percent area of fibrosis and caspase-3 immunoexpression was significantly increased. Ultrastructurally, irregular tubular basement membrane and damaged germ cells were found. The spermatogenic, Sertoli, and Leydig cells showed irregular shrunken nuclei, cytoplasmic vacuolations, and swollen mitochondria. MSG + SE group showed much better histological and ultrastructural picture and improvement of the measured biochemical and morphometric parameters. Percent area of caspase-3 immunoexpression was significantly decreased. In conclusion, sodium selenite ameliorated the testicular damaging effect of MSG through reduction of oxidative stress and apoptosis.

Nut Consumption and Lung Cancer Risk: Results from Two Large Observational Studies

Background: Epidemiologic evidence on the association between nut consumption and lung cancer risk is limited.Methods: We investigated this relationship in the Environment and Genetics in Lung Cancer Etiology (EAGLE) study, a population-based case-control study, and the National Institutes of Health (NIH) American Association of Retired Persons (AARP) Diet and Health Study, a prospective cohort. We identified 2,098 lung cases for EAGLE and 18,533 incident cases in AARP. Diet was assessed by food frequency questionnaire for both studies. Multivariable ORs and HRs and respective 95% confidence intervals (CI) were calculated using unconditional logistic regression and Cox proportional hazards regression for EAGLE and AARP, respectively.Results: Higher frequency of intake of nut consumption was inversely associated with overall lung cancer risk (highest vs. lowest quintile, OR_EAGLE = 0.74; 95% CI, 0.57-0.95; HR_AARP = 0.86; 95% CI, 0.81-0.91), regardless of smoking status. Results from the prospective cohort showed similar associations across histologic subtypes and a more pronounced benefits from nut consumption for those who smoked 1 to 20 cigarettes/day (OR_EAGLE = 0.61; 95% CI, 0.39-0.95; HR_AARP = 0.83; 95% CI, 0.74-0.94).Conclusions: Nut consumption was inversely associated with lung cancer in two large population-based studies, and associations were independent of cigarette smoking and other known risk factors.Impact: To our knowledge, this is the first study that examined the association between nut consumption and lung cancer risk by histologic subtypes and smoking intensity. Cancer Epidemiol Biomarkers Prev; 26(6); 826-36. ©2017 AACR.

Protective effects of sodium selenite supplementation against irradiation-induced damage in non-cancerous human esophageal cells

The administration of radioprotective compounds is one approach to preventing radiation damage in non-cancerous tissues. Therefore, radioprotective compounds are crucial in clinical radiotherapy. Selenium is a radioprotective compound that has been used in previous clinical studies of radiotherapy. However, evidence regarding the effectiveness of selenium in radiotherapy and the mechanisms underlying the selenium-induced reduction of the side effects of radiotherapy remains insufficient. To further investigate the effectiveness of selenium in radiotherapy, the present study examined the protective effects of sodium selenite supplementation administered prior to X-ray radiation treatment in CHEK-1 non-cancerous human esophageal cells. Sodium selenite supplementation increased glutathione peroxidase 1 (GPx-1) activity in a dose- and time-dependent manner. The sodium selenite dose that induced the highest GPx-1 activity was determined to be 50 nM for 72 h prior to radiotherapy. The half-maximal inhibitory concentration of sodium selenite in CHEK-1 cells was 3.6 µM. Sodium selenite supplementation increased the survival rate of the cells in a dose-dependent manner and enhanced the degree of cell viability at 72 h post-irradiation (P<0.05). Combined treatment with 50 nM sodium selenite and 2 gray (Gy) X-ray irradiation decreased the number of sub-G₁ cells from 5.9 to 4.2% (P<0.05) and increased the proportion of G₁ cells from 58.8 to 62.1%, compared with 2 Gy X-ray irradiation alone; however, this difference was not statistically significant (P=1.00). Western blot analysis revealed that treatment with 2 Gy X-ray irradiation significantly increased the expression levels of cleaved poly (ADP-ribose) polymerase (PARP; P<0.05). In addition, combined treatment with 50 nM sodium selenite and 2 Gy X-ray irradiation reduced the expression levels of cleaved PARP protein, compared with 2 Gy X-ray irradiation alone; however, this reduction was not statistically significant (P=0.423). These results suggest that 50 nM sodium selenite supplementation administered for 72 h prior to irradiation may protect CHEK-1 cells from irradiation-induced damage by inhibiting irradiation-induced apoptosis. Therefore, sodium selenite is a potential radioprotective compound for non-cancerous cells in clinical radiotherapy.

Differences in Redox Regulatory Systems in Human Lung and Liver Tumors Suggest Different Avenues for Therapy

A common characteristic of many cancer cells is that they suffer from oxidative stress. They, therefore, require effective redox regulatory systems to combat the higher levels of reactive oxygen species that accompany accelerated growth compared to the normal cells of origin. An elevated dependence on these systems in cancers suggests that targeting these systems may provide an avenue for retarding the malignancy process. Herein, we examined the redox regulatory systems in human liver and lung cancers by comparing human lung adenocarcinoma and liver carcinoma to their respective surrounding normal tissues. Significant differences were found in the two major redox systems, the thioredoxin and glutathione systems. Thioredoxin reductase 1 levels were elevated in both malignancies, but thioredoxin was highly upregulated in lung tumor and only slightly upregulated in liver tumor, while peroxiredoxin 1 was highly elevated in lung tumor, but downregulated in liver tumor. There were also major differences within the glutathione system between the malignancies and their normal tissues. The data suggest a greater dependence of liver on either the thioredoxin or glutathione system to drive the malignancy, while lung cancer appeared to depend primarily on the thioredoxin system.

Dietary Selenium Levels Affect Selenoprotein Expression and Support the Interferon-γ and IL-6 Immune Response Pathways in Mice

Selenium is an essential element that is required to support a number of cellular functions and biochemical pathways. The objective of this study was to examine the effects of reduced dietary selenium levels on gene expression to assess changes in expression of non-selenoprotein genes that may contribute to the physiological consequences of selenium deficiency. Mice were fed diets that were either deficient in selenium or supplemented with selenium in the form of sodium selenite for six weeks. Differences in liver mRNA expression and translation were measured using a combination of ribosome profiling, RNA-Seq, microarrays, and qPCR. Expression levels and translation of mRNAs encoding stress-related selenoproteins were shown to be up-regulated by increased selenium status, as were genes involved in inflammation and response to interferon-γ. Changes in serum cytokine levels were measured which confirmed that interferon-γ, as well as IL-6, were increased in selenium adequate mice. Finally, microarray and qPCR analysis of lung tissue demonstrated that the selenium effects on immune function are not limited to liver. These data are consistent with previous reports indicating that adequate selenium levels can support beneficial immune responses, and further identify the IL-6 and interferon-γ pathways as being responsive to dietary selenium intake.

Selenocystine-induced cell apoptosis and S-phase arrest inhibit human triple-negative breast cancer cell proliferation

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited effective treatment options. New therapeutic approaches are urgently needed to improve the prognosis of TNBC. Here we demonstrated that a redox modulator, selenocystine (SeC), significantly inhibits TNBC cell proliferation in a dose- and time-dependent manner. Through cell apoptosis assays and cell cycle distribution analyses, we have shown that the in vitro inhibitory effect of SeC on TNBC cells can be attributed to the induction of apoptosis and the S-phase arrest in a dose-dependent manner. Therefore, this finding implies that SeC potentially is a novel therapeutic agent for TNBC.

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.

Selenium and exposure to fibrogenic mineral dust: a mini-review

Individuals exposed to fibrogenic mineral dust may exhibit an impaired antioxidant system and produce high levels of reactive oxygen and nitrogen species through immune cells, contributing to the perturbation of immune cell function, inflammation, fibrosis and lung cancer. The lung diseases which are caused by inhalation of fibrogenic mineral dust, known as pneumoconioses, develop progressively and irreversibly over decades. At the moment there is no known cure. The trace element selenium has potent antioxidant and anti-inflammatory properties mediated mainly through selenoproteins. Research has demonstrated that selenium has the ability to protect against cardiovascular diseases; to kill cancer cells in vitro and reduce cancer incidence; and to immunomodulate various cellular signaling pathways. For these reasons, selenium has been proposed as a promising therapeutic agent in oxidative stress associated pathology that in theory would be beneficial for the prevention or treatment of pneumoconioses such as silicosis, asbestosis, and coal worker's pneumoconiosis. However, studies regarding selenium and occupational lung diseases are rare. The purpose of this study is to conduct a mini-review regarding the relationship between selenium and exposure to fibrogenic mineral dust with emphasis on epidemiological studies. We carried out a systematic literature search of English published studies on selenium and exposure to fibrogenic mineral dust. We found four epidemiological studies. Reviewed studies show that selenium is lower in individuals exposed to fibrogenic mineral dust. However, three out of the four reviewed studies could not confirm cause-and-effect relationships between low selenium status and exposure to fibrogenic mineral dust. This mini-review underscores the need for large follow-up and mechanistic studies for selenium to further elucidate its therapeutic effects.

Effects of selenium on proliferation, interleukin-2 production and selenoprotein mRNA expression of normal and dexamethasone-treated porcine splenocytes

Porcine splenocytes were isolated in vitro, treated with different levels of dexamethasone (DEX), and stimulated by concanavalin A. Further, the normal (non-DEX-supplemented) or DEX-treated (0.01 µmol/L) splenocytes were incubated with 0, 0.5, 2, and 5 µmol/L Na2SeO3. The splenocyte proliferation, IL-2 production, intracellular glutathione peroxidase 1 (GPx1) mRNA level and activity and thioredoxin reductase 1 mRNA level were measured. The results showed that addition of 0.5 or 2 µmol/L Na2SeO3 significantly promoted normal and DEX-treated splenocyte proliferation, IL-2 production and GPx1 mRNA expression and activity (P < 0.05), respectively. The maximum effect was observed in DEX-treated splenocytes with 0.5 µmol/L Na2SeO3. Thus, our results show that the immune state modulation of Se is stronger in DEX-treated splenocytes than normal splenocytes. The mechanism underlying this effect may be increased in GPx1 expression induced by Se. Our results explain the controversy of varying reports on the immune state modulation induced by Se.

An assessment of antioxidant status in patients with carbon monoxide poisoning

BACKGROUND

Carbon monoxide poisoning (COP) is an important cause of mortality and morbidity worldwide. This study was to investigate the levels of serum paraoxonase (PON), arylesterase (ARYL), ceruloplasmin (Cp), and sulfhydryl (-SH) in the treatment of COP, and to further understand the pathophysiology of COP.

METHODS

This prospective study comprised 107 individuals with COP (group 1) and 50 healthy volunteers (group 2). Serum, plasma, and erythrocyte samples were taken on admission from all participants with COP. This process was repeated in the 90(th) and 180(th) minutes of treatment. Samples were taken from the control group only once. The levels of plasma PON, ARYL, Cp activity and -SH were measured in both groups.

RESULTS

Age, gender, and carboxyhemoglobin level were not correlated with PON, ARYL, Cp, and -SH levels. PON, ARYL, and -SH levels were significantly decreased in group 1 compared with group 2. Conversely, Cp was significantly elevated in group 1 in contrast to group 2. Although ARYL was lower on admission in patients with COP than that was observed in the 90(th) and 180(th) minutes (P<0.001), Cp was higher on admission than at the other time points (P<0.001).

CONCLUSIONS

Participants with COP had decreased levels of antioxidants (PON, ARLY, and -SH). COP represses the antioxidant system.

Plasma selenium levels and oxidative stress biomarkers: a gene-environment interaction population-based study

The role of selenium exposure in preventing chronic disease is controversial, especially in selenium-repleted populations. At high concentrations, selenium exposure may increase oxidative stress. Studies evaluating the interaction of genetic variation in genes involved in oxidative stress pathways and selenium are scarce. We evaluated the cross-sectional association of plasma selenium concentrations with oxidative stress levels, measured as oxidized to reduced glutathione ratio (GSSG/GSH), malondialdehyde (MDA), and 8-oxo-7,8-dihydroguanine (8-oxo-dG) in urine, and the interacting role of genetic variation in oxidative stress candidate genes, in a representative sample of 1445 men and women aged 18-85 years from Spain. The geometric mean of plasma selenium levels in the study sample was 84.76 µg/L. In fully adjusted models the geometric mean ratios for oxidative stress biomarker levels comparing the highest to the lowest quintiles of plasma selenium levels were 0.61 (0.50-0.76) for GSSG/GSH, 0.89 (0.79-1.00) for MDA, and 1.06 (0.96-1.18) for 8-oxo-dG. We observed nonlinear dose-responses of selenium exposure and oxidative stress biomarkers, with plasma selenium concentrations above ~110 μg/L being positively associated with 8-oxo-dG, but inversely associated with GSSG/GSH and MDA. In addition, we identified potential risk genotypes associated with increased levels of oxidative stress markers with high selenium levels. Our findings support that high selenium levels increase oxidative stress in some biological processes. More studies are needed to disentangle the complexity of selenium biology and the relevance of potential gene-selenium interactions in relation to health outcomes in human populations.

Cross-talk between apoptosis and autophagy in lung epithelial cell death

As an essential organ for gas exchange, the lungs are constantly exposed to the external environment and are simulated by toxicants and pathogens. The integrity of lung epithelium and epithelial cells is crucial for fulfilling the physiological functions of the lung. The homeostasis of lung epithelial cells is maintained by a complex network by which survival and death are tightly regulated. Upon noxious stimulation, lung epithelium attempts to maintain its normal structure and function. Savage of injured cells and clearance of unsalvageable dying cells or unwanted proliferated cells constantly occur in the lung epithelium. Apoptosis, or programmed cell death, functions as a primary mechanism to discard unsalvageable cells or unwanted overgrowth. Autophagy, on the other hand, initially attempts to save and repair the injured cells. However, when the noxious stimulation is too strong and cell survival becomes unfeasible, autophagy behaves oppositely and cooperates with apoptosis, subsequently accelerates cell death. The imbalance between autophagy and apoptosis potentially leads to tumorigenesis or devastating cell death/lung injury. Therefore, the cross-talk between apoptosis and autophagy in lung epithelial cells is critical in determining the fate of epithelial cells and its balance of death/survival in response to environmental stimuli. In this review, we will focus on the current understandings of the communications between apoptosis and autophagy in lung epithelial cells. We will review multiple key regulators and their underlying mechanisms involved in the cross-talk between apoptosis and autophagy. The autophagic factors, such as the Beclin-1, ATG5, Fap-1, p62 and concentration-dependent LC3B, all closely interact with multiple apoptosis pathways. Understanding these regulations of apoptosis/autophagy cross-talk potentially provides novel targets for developing diagnostic and therapeutic strategies for many lung diseases, including lung injuries and malignancies.

The relationship between selenium levels and breast cancer: a systematic review and meta-analysis

Breast cancer is the most common cancer type. In several studies, hints have been provided that there is a correlation between selenium deficiency and the incidence of breast cancer. Findings of these published reports are, however, inconsistent. This study serves as a pioneering study aiming at combining the results of studies using a meta-analytic method. A total of 16 articles published between 1980 and 2012 worldwide were selected through searching PubMed, Scopus, and Google scholar databases, and the information were analyzed using a meta-analytic method [random effects model]. I (2) statistics were used to examine heterogeneity. The information was then analyzed by STATA version 12. In this study, due to the non-uniform methods used to measure selenium concentrations, selenium levels were measured in the various subgroups in both case and control groups. There were significant correlations between selenium concentration and breast cancer [P<0.05]. Hence, the mean risk differentiating criteria were estimated to be 0.63 [95% confidence interval [95% CI] 0.93 to 0.32] in serum and toenails. Subgroup analysis showed that the value in toenails was -0.07 [95% CI -0.16 to 0.03] and in serum -1.04 [95% CI 1.71 to -0.38]. In studies in which selenium concentrations were measured in serum, a significant correlation was observed between selenium concentration and breast cancer. In contrast, in studies in which selenium concentration was measured in toenails, the correlation was not significant. Therefore, the selenium concentration can be used as one predictor for breast cancer.

Updates on clinical studies of selenium supplementation in radiotherapy

To establish guidelines for the selenium supplementation in radiotherapy we assessed the benefits and risks of selenium supplementation in radiotherapy. Clinical studies on the use of selenium in radiotherapy were searched in the PubMed electronic database in January 2013. Sixteen clinical studies were identified among the 167 articles selected in the initial search. Ten articles were observational studies, and the other 6 articles reported studies on the effects of selenium supplementation in patients with cancer who underwent radiotherapy. The studies were conducted worldwide including European, American and Asian countries between 1987 and 2012. Plasma, serum or whole blood selenium levels were common parameters used to assess the effects of radiotherapy and the selenium supplementation status. Selenium supplementation improved the general conditions of the patients, improved their quality of life and reduced the side effects of radiotherapy. At the dose of selenium used in these studies (200–500 μg/day), selenium supplementation did not reduce the effectiveness of radiotherapy, and no toxicities were reported. Selenium supplementation may offer specific benefits for several types of cancer patients who undergo radiotherapy. Because high-dose selenium and long-term supplementation may be unsafe due to selenium toxicity, more evidence-based information and additional research are needed to ensure the therapeutic benefits of selenium supplementation.

A prospective study of plasma Selenoprotein P and lung cancer risk among low-income adults

BACKGROUND

Epidemiologic studies have shown increased risks of lung cancer among adults with low blood levels of selenium, although evidence is inconsistent. In the United States, the incidence of lung cancer is higher and mean serum selenium levels lower among Blacks than Whites, but prior studies have not assessed the selenium-lung cancer association among Blacks.

METHODS

From the prospective Southern Community Cohort Study, we identified 372 participants who provided blood samples and subsequently developed lung cancer. Selenoprotein P (SEPP1), the most abundant selenoprotein in plasma and a biomarker of selenium nutriture, was measured in the plasma from these individuals and from 716 matched controls.

RESULTS

Mean SEPP1 levels were significantly (P < 0.0001) lower among Blacks than Whites. Conditional logistic regression models accounting for smoking revealed a significant trend of increasing OR of lung cancer with decreasing SEPP1 tertiles among Blacks (P = 0.0006) but not Whites (P = 0.69; Pinteraction = 0.10). The ORs and corresponding 95% confidence intervals of lung cancer risk among those with lowest versus highest tertile levels of SEPP1 were 2.4 (1.5-3.0) among Blacks and 1.1 (0.6-2.1) among Whites.

CONCLUSIONS

Among a mostly low-income population in the southeastern United States, lower levels of SEPP1 were associated with an increasing risk of lung cancer among Blacks but not Whites.

IMPACT

The combined findings of higher prevalence of low selenium status and higher lung cancer risk associated with low status raise the possibility that selenium deficiency may contribute to observed racial disparities in lung cancer incidence.

Biological and chemical investigation of Allium cepa L. response to selenium inorganic compounds

The aim of this study was to evaluate the biological and chemical response of Allium cepa L. exposed to inorganic selenium compounds. Besides the investigation of the total content of selenium as well as its chemical speciation, the Allium test was used to evaluate the growth of onion roots and mitotic activity in the roots' meristem. The total content of selenium was determined by inductively coupled plasma mass spectrometry (ICP MS). High-performance liquid chromatography (HPLC), coupled to ICP MS, was used for the selenium chemical speciation. Results indicated that A. cepa plants are able to biotransform inorganic selenium compounds into their organic derivatives, e.g., Se-methylselenocysteine from the Se(IV) inorganic precursor. Although the differences in the biotransformation of selenium are due mainly to the oxidation state of selenium, the experiment has also shown a fine effect of counter ions (H(+), Na(+), NH4 (+)) on the response of plants and on the specific metabolism of selenium.

Inflammation, DAMPs, tumor development, and progression: a vicious circle orchestrated by redox signaling

SIGNIFICANCE

Increasing evidence indicates that cancer development and progression are promoted by the joint action of redox distress and inflammation, supporting the potential impact of therapies aimed at restoring the redox homeostasis and fighting inflammation.

RECENT ADVANCES

Most of the literature of the last 40 years converges to the view that continuous oxidative stress and chronic inflammation sustain each other, leads to transformation of a normal cell to a neoplastic cell, and promotes tumor progression. Some recent findings, however, support an alternative model whereby the increased production of reactive oxygen species (ROS) is an attempt to defend more than a pathogenetic factor in cancer. Rather, tumor development and progression may be promoted by an excess of antioxidants, induced in both transformed cells and recruited inflammatory cells as an adaptive response to ROS.

CRITICAL ISSUES

Although the link among redox stress, chronic inflammation, and cancer is widely recognized, the underlying mechanisms are far to be understood. The redox unbalance of the microenvironment is likely to modulate the bioactivity of damage-associated molecular pattern molecules such as HMGB1, which are released by stressed tissues and play pleiotropic functions on tumor and inflammatory cells, but how this occur, and the relevant consequences, are still unclear.

FUTURE DIRECTIONS

In vivo measurement of cell redox status is an important challenge for future investigations. The improvement of the methodologies for ROS and antioxidant detection will allow a better understanding of the redox-related events in the tumor microenvironment with tremendous application potential in the development of rational combination therapies for cancer treatment.

Supplementation with sodium selenite and selenium-enriched microalgae biomass show varying effects on blood enzymes activities, antioxidant response, and accumulation in common barbel (Barbus barbus)

Yearling common barbel (Barbus barbus L.) were fed four purified casein-based diets for 6 weeks in outdoor cages. Besides control diet, these were supplemented with 0.3 mg kg⁻¹ dw selenium (Se) from sodium selenite, or 0.3 and 1.0 mg kg⁻¹ from Se-enriched microalgae biomass (Chlorella), a previously untested Se source for fish. Fish mortality, growth, Se accumulation in muscle and liver, and activity of selected enzymes in blood plasma, muscle, liver, and intestine were evaluated. There was no mortality, and no differences in fish growth, among groups. Se concentrations in muscle and liver, activity of alanine aminotransferase and creatine kinase in blood plasma, glutathione reductase (GR) in muscle, and GR and catalase in muscle and liver suggested that selenium from Se-enriched Chlorella is more readily accumulated and biologically active while being less toxic than sodium selenite.

Association of Merkel cell polyomavirus infection with EGFR mutation status in Chinese non-small cell lung cancer patients

OBJECTIVES

Female lung cancer patients with no smoking habit and non-mucinous adenocarcinoma have a higher rate of epidermal growth factor receptor (EGFR) gene mutations, which is related to tyrosine kinase inhibitors (TKIs) sensitivity. Unfortunately the cause of EGFR gene mutations is still elusive. In this study, we search for the association between Merkel cell polyomavirus (MCPyV) infection and EGFR gene mutations.

MATERIALS AND METHODS

We studied 189 non-small cell lung cancer (NSCLC) samples for the presence of MCPyV large T (LT) DNA, LT antigen and EGFR hotspot mutations. Clinicopathological parameters of this cohort were also analyzed.

RESULTS

Thirty out of 163 adenocarcinoma and 2 out of 18 squamous cell carcinoma were found to have MCPyV LT DNA by PCR. Immunostaining also showed LT protein expression in most of the DNA positive samples. EGFR mutations were more frequently detected in female (P=0.009) and non-smoking patients (P=0.0001). Furthermore, a significant association between MCPyV infection and EGFR mutations was found (P=0.001).

CONCLUSION

Our study shows that MCPyV LT DNA is present in a subgroup of NSCLC, which is significantly correlated with EGFR mutations. To the best of our knowledge, this is the first study to find an association between MCPyV infection and EGFR hotspot mutations. These results support the possibility that MCPyV has a partial role in the carcinogenesis of NSCLC in a subgroup of patients.

Metabolism of selenite to selenosugar and trimethylselenonium in vivo: tissue dependency and requirement for S-adenosylmethionine-dependent methylation

Impaired S-adenosylmethionine (SAM)-dependent transmethylation and methylation capacity feature in diseases related to obesity or aging, and selenium (Se) metabolism is altered in these states. We tested the hypothesis that SAM metabolism is required for methylation and excretion of Se in a rat model. Four hours after selenite and periodate-oxidized adenosine (POA; an inhibitor of SAM metabolism) were administered, circulating markers of single-carbon status were unchanged, except for decreased circulating phosphatidylcholine (P<.05). In contrast, liver and kidney SAM and S-adenosylhomocysteine were elevated (P<.05 for all). Concentrations of total Se were significantly elevated in both liver (P<.001) and kidney (P<.01), however the degree of accumulation in liver was significantly greater than that of kidney (P<.05). Red blood cell Se levels were decreased (P=.01). Trimethylselenonium levels were decreased in liver and kidney (P=.001 for both tissues) and Se-methyl-N-acetylselenohexosamine selenosugar was decreased in liver (P=.001). Urinary output of both trimethylselenonium (P=.001) and selenosugar (P=.01) was decreased as well. Trimethylselenonium production is more inhibited by POA than is selenosugar production (P<.05). This work indicates that low molecular weight Se metabolism requires SAM-dependent methylation, and disrupting the conversion of SAM to S-adenosylhomocysteine prevents conversion of selenite and intermediate metabolites to final excretory forms, suggesting implications for selenium supplementation under conditions where transmethylation is suboptimal, such as in the case of obese or aging individuals.

A pilot study of serum selenium, vitamin D, and thyrotropin concentrations in patients with thyroid cancer

BACKGROUND

Low serum selenium concentrations have been associated with a diagnosis of differentiated thyroid cancer in small studies in selenium deficient areas. We conducted a pilot study to explore associations between selenium concentrations and the diagnosis of thyroid cancer in an area of selenium sufficiency in the United States. As low 25-hydroxyvitamin D concentrations have been associated with several malignancies, we also examined 25-hydroxyvitamin D levels.

METHODS

This study was designed as a pilot study of prediagnostic selenium and 25-hydroxyvitamin D concentrations. We identified 65 euthyroid patients at an academic medical center who were scheduled for thyroidectomy for thyroid cancer, suspicion of thyroid cancer, or nodular disease. Blood samples were obtained two to four weeks prior to thyroidectomy. Samples were analyzed for thyrotropin (TSH), free thyroxine, total triiodothyronine, selenium, and 25 hydroxyvitamin D levels. Concentrations of these analytes were correlated with whether the patient was diagnosed with benign or malignant disease following their thyroidectomy. In patients with thyroid cancer, the concentrations of selenium and 25-hydroxyvitamin D were correlated with various prognostic features.

RESULTS

Although selenium concentrations were not significantly lower in patients with thyroid cancer, serum selenium concentrations were inversely correlated with disease stage (p = 0.011). There were no associations between vitamin D concentration and a diagnosis of thyroid cancer. Within the thyroid cancer patients, vitamin D concentrations were not associated with disease stage or any other prognostic features. In contrast, TSH concentrations were significantly higher in patients with thyroid cancer, and were positively correlated with the number of involved lymph nodes (p = 0.011) and disease stage (p = 0.022).

CONCLUSION

These data confirm the association between serum TSH and advanced thyroid cancer. In addition, they also suggest a potential association between selenium concentrations and higher thyroid cancer stage. No such association was seen for 25-hydroxyvitamin D concentrations. Larger prospective studies will be required to confirm this association. If confirmed, future studies would need to determine if the association is causative in nature. If causation exists, it seems likely that selenium concentrations would influence thyroid cancer development via an independent mechanism from that of TSH.

Chemoprevention of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Lung cancer is the most common cause of cancer death in men and women in the United States. Cigarette smoking is the main risk factor. Former smokers are at a substantially increased risk of developing lung cancer compared with lifetime never smokers. Chemoprevention refers to the use of specific agents to reverse, suppress, or prevent the process of carcinogenesis. This article reviews the major agents that have been studied for chemoprevention.

METHODS

Articles of primary, secondary, and tertiary prevention trials were reviewed and summarized to obtain recommendations.

RESULTS

None of the phase 3 trials with the agents β-carotene, retinol, 13-cis-retinoic acid, α-tocopherol, N-acetylcysteine, acetylsalicylic acid, or selenium has demonstrated beneficial and reproducible results. To facilitate the evaluation of promising agents and to lessen the need for a large sample size, extensive time commitment, and expense, surrogate end point biomarker trials are being conducted to assist in identifying the most promising agents for later-stage chemoprevention trials. With the understanding of important cellular signaling pathways and the expansion of potentially important targets, agents (many of which target inflammation and the arachidonic acid pathway) are being developed and tested which may prevent or reverse lung carcinogenesis.

CONCLUSIONS

By integrating biologic knowledge, additional early-phase trials can be performed in a reasonable time frame. The future of lung cancer chemoprevention should entail the evaluation of single agents or combinations that target various pathways while working toward identification and validation of intermediate end points.

Can selenium levels act as a marker of colorectal cancer risk?

Background

Selenium has attracted attention because of its antioxidant properties. Antioxidants protects cells from damage. Certain breakdown products of selenium are believed to prevent tumor growth by enhancing the immune cell activity and suppressing the development of tumor blood vessels. In this observational study, selenium level was measured in a series of patients from Poland and Estonia to determine a correlation between levels of this microelement and colorectal cancer risk.

Methods

A total of 169 colorectal cancer patients and 169 healthy controls were enrolled in the study after obtaining their informed consent. Selenium level in the blood serum was measured using Graphite Furnace Atomic Absorption Spectrometry (GFAAS). The statistical analysis was performed by Fisher’s exact test.

Results

The threshold point of selenium level was 55 μg/l and 65 μg/l for Poland and Estonia respectively, for an increase in cancer risk. The lower levels of selenium were associated with greater risk of colorectal cancer.

Conclusions

The result reveals a significant strong association between low selenium level and the colorectal cancer risk in both Estonian and Polish populations.

Selenium: a brief review and a case report of selenium responsive cardiomyopathy

BACKGROUND

The authors review the role of selenium and highlight possible low selenium levels in soil that may result in deficient states in Saudi Arabia.

CASE PRESENTATION

The authors report a case of selenium-responsive cardiomyopathy in a 15-month old Saudi Arabian boy. This case of selenium deficiency causing dilated cardiomyopathy is presented with failure to thrive, prolonged fever and respiratory distress. The investigations revealed selenium deficiency. Selenium supplementation along with anti-failure therapy [Furosimide, Captopril] was administered for 6 months. Following therapy the cardiac function, hair, skin and the general health of the patient improved significantly.

CONCLUSION

The patient with dilated cardiomyopathy of unknown etiology, not responding to usual medication may be deficient in selenium. Serum selenium measurements should be included in the diagnostic work-up to ensure early detection and treatment of the disease. The selenium level in the Saudi population needs be determined. Vulnerable populations have to undergo regular selenium measurements and supplementation if indicated. Dependence on processed foods suggests that the Saudi population fortify themselves with nutrient and micronutrient supplements in accordance to the RDA.