A comparative study of selenium concentration and glutathione peroxidase activity in normal and breast cancer patients

Abstract

Objective: The present study was undertaken to compare plasma Se values and glutathione peroxidase (GPX) activity in normal and breast cancer patients. Design: In a case-control study, forty-five breast cancer patients and the same number of healthy women were randomly selected from their population. Se was measured in plasma by atomic absorption spectrophotometry and GPX activity in erythrocytes was measured using a standard spectrophotometric method. Results: Plasma Se concentration in healthy women and breast cancer patients was in the normal range, with no statistically significant difference observed between the two groups (138?40 (SD 40?36) mg/l v. 132?15 (SD 35?37) mg/l, respectively). Erythrocyte GPX activity was significantly (P , 0?01) higher in breast cancer patients (24?81 (SD 11?66) U/g Hb) compared with healthy women (20?29 (SD 4?24) U/g Hb).Conclusion: The present study indicated that Se deficiency was not a problem in the participants, and sufficient quantity of this element could increase GPX activity to have a protective effect against oxidative damage. Keywords Antioxidant Breast cancer Glutathione peroxidase SeleniumBreast cancer is the most common malignancy in women, with 1 million new cases worldwide each year, and comprises 18 % of female cancers (1) . In the Middle East, breast cancer is the most common malignancy among women (2) . Similarly in Iran, breast cancer is the highest in rank among cancers of women and accounts for 21?4 % of all malignancies in females (3) . There is evidence that Se as an essential trace element has anticancer properties (4)(5)(6)(7) . Research spanning the last 35 years has established that Se is effective in the reduction of cancer incidence when provided to animals at non-toxic dose (five to ten times the nutritional requirement) (8,9) . But for researchers conducting studies on Se and cancer prevention, the most exciting news in recent years has been the finding of Clark et al. (10) indicating that the supplementation of freeliving people with selenized brewer's yeast decreases overall cancer morbidity and mortality by nearly 50 %.Epidemiological data have also supported a protective effect of Se in man with regard to the prevention of both prostate cancer (11,12) and lung cancer (13) . The relationship between Se status and the incidence of breast cancer needs to be clarified, however, because one study indicates a protective effect (14) whereas other studies have not shown any protective effect (15)(16)(17)(18) . Cellular oxidative damage is a well-established general mechanism for cell and tissue injury. Oxidative damage to cells is caused primarily by free radicals and reactive oxygen species. Free radicals have the ability to bind to most normal cellular components; they react with unsaturated bonds of membrane lipids, denature proteins and attack nucleic acids. Prime targets of reactive oxygen species are the PUFA in cell membranes, causing lipid peroxidation which may lead to damage of cellular structure and function (19) . Oxidative stress...

Selenium and breast cancer risk: A prospective nested case–control study on serum selenium levels, smoking habits and overweight

“…17 The association between Se and breast cancer has been studied for a long period, though previous research has not been conclusive. Similar to our results, Hunter et al (1990) and Moradi et al (2009) found no significant association between Se levels and breast cancer. 17,31 However, several studies, including Hardell et al (1993) and Rejali et al (2007) did find a significant association between low Se (in plasma and serum, respectively) and an increased risk of breast cancer.…”

“…Similar to our results, Hunter et al (1990) and Moradi et al (2009) found no significant association between Se levels and breast cancer. 17,31 However, several studies, including Hardell et al (1993) and Rejali et al (2007) did find a significant association between low Se (in plasma and serum, respectively) and an increased risk of breast cancer. 12,20 Two recent meta-analyses also suggest an association.…”

Antioxidant Activity of Sulfur and Selenium: A Review of Reactive Oxygen Species Scavenging, Glutathione Peroxidase, and Metal-Binding Antioxidant Mechanisms

“…Not all studies observe a correlation between selenium deficiency and increased cancer incidence. Atomic absorption spectroscopy was used to determine the selenium concentration in blood samples from 45 patients with breast cancer and found no significant deficiency in selenium levels versus healthy controls [223].…”

Selenium and cancer

“…On the other hand, a number of studies failed to find such relationships, or only found it in specific subgroups, such as smokers [11][12][13][14][15] .…”