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

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

Se Status Prediction by Food Intake as Compared to Circulating Biomarkers in a West Algerian Population.

Algeria is the largest country in Africa, located close to the Mediterranean coastal area, where nutrients consumption varies widely. Local data on selenium composition of foods are not available. We postulated a close correlation between selenium status predictions from food consumption analysis with a quantitative analysis of circulating biomarkers of selenium status. Population characteristics were recorded from 158 participants and dietary selenium intake was calculated by 24-h recall. The average total plasma selenium was 92.4 ± 18.5 µg/L and the mean of selenium intake was 62.7 µg/day. The selenoprotein P concentration was 5.5 ± 2.0 mg/L and glutathione peroxidase 3 activity was 247.3 ± 41.5 U/L. A direct comparison of the dietary-derived selenium status to the circulating selenium biomarkers showed no significant interrelation. Based on absolute intakes of meat, potato and eggs, a model was deduced that outperforms the intake composition-based prediction from all food components significantly (DeLong's test, p = 0.029), yielding an area under the curve of 82%. Selenium status prediction from food intake remains a challenge. Imprecision of survey method or information on nutrient composition makes extrapolating selenium intake from food data providing incorrect insights into the nutritional status of a given population, and laboratory analyses are needed for reliable information.

Selenium overexposure induces insulin resistance: In silico study.

BACKGROUND AND AIMS: Several studies raise concerns about the possible association of high selenium exposure with insulin resistance and type 2 diabetes. This in silico study proposes a possible mechanism of insulin resistance in the case of overexposure to selenium. METHOD: A study was carried out using molecular modeling, where cysteines of the insulin-receptor are replaced by selenocysteines. Calculation of the interaction energy of the receptor was performed in both cases with Auto Dock Tools and Vina 4.2 software to predict whether the substitution of amino acid could lead to destabilization of the protein-ligand complex and therefore possibly insulin resistance. Finally, the docked complex was analyzed by using BIOVIA Discovery Studio Visualizer to show the type of interactions between the ligands and insulin-receptor, and to determine the distance of the ligands from the binding site on insulin-receptor. RESULTS: The results show that the substitution of cysteine by selenocysteine in the insulin receptor does not lead to stabilization of the complex receptor/insulin, but to its disruption.In addition, the types and the number of bonds between insulin and its receptor in the two cases are different, where 7 strong bonds between insulin and its receptor were found in the case of the cysteine complex compared to 6 weak bonds in the second case. CONCLUSION: Findings of this study suggest that misincorporation of selenocysteines in insulin receptor could lead to destabilization of the insulin-receptor complex and therefore may possibly cause an insulin resistance.