cysteinylglycine and Breast-Neoplasms

Different low-molecular-weight thiols, including glutathione, cysteine, and cysteinylglycine are physiological free radical scavengers. On the other hand, homocysteine may play a role as an oxidant. The aim of our present study was to establish in vitro the effects of the commercial extract of Aronia melanocarpa (Aronox(®)) on the amount of selected low-molecular-weight thiols and the activity of antioxidative enzymes (superoxide dismutase, glutathione peroxidase, and glutathione reductase) in plasma obtained from patients with invasive breast cancer during different phases of treatment [before or after the surgery and patients after different phases of chemotherapy (doxorubicin and cyclophosphamide)] and from healthy subjects. Patients were hospitalized in Department of Oncological Surgery and Department of Chemotherapy, Medical University of Lodz, Poland. The level of low-molecular-weight thiols was determined by high-performance liquid chromatography. We observed that in the presence of the Aronia extract changes in amount of thiols in plasma from breast cancer patients (at all tested groups) were significantly reduced. Our results showed that tested commercial extract reduced modifications of antioxidative enzymes activity in plasma from patients during different phases of treatment, but this effect was not statistical significant. Our results suggest that the Aronia extract supplementation in breast cancer patients has a beneficial effect on thiols concentration in plasma. Plasma, as reported in this work, could be used as an experimental model to evaluate the beneficial action of plant supplements, including phenolic extracts on thiols or other molecules during different phases of treatment.

Topics: Adult; Aged; Antibiotics, Antineoplastic; Antineoplastic Agents, Alkylating; Antioxidants; Breast Neoplasms; Carcinoma, Ductal, Breast; Case-Control Studies; Combined Modality Therapy; Cyclophosphamide; Cysteine; Dipeptides; Doxorubicin; Female; Glutathione; Glutathione Peroxidase; Glutathione Reductase; Humans; Middle Aged; Photinia; Plant Extracts; Superoxide Dismutase

Cysteinylglycine, a prooxidant generated during the catabolism of glutathione, has been suggested to induce oxidative stress and lipid peroxidation, leading to the development of human cancers. Observational data relating cysteinylglycine status to breast cancer risk are lacking. We prospectively evaluated plasma cysteinylglycine levels and invasive breast cancer risk among 812 case-control pairs nested in the Women's Health Study, a completed randomized trial evaluating low-dose aspirin and vitamin E in middle-aged and older women. We additionally evaluated the effect modification by risk factors for oxidative stress, such as vitamin E assignment, alcohol consumption, obesity, and postmenopausal hormone use. Logistic regression controlling for matching factors, as well as other risk factors for breast cancer, was used to estimate relative risks (RR) and 95% confidence intervals (95% CI). All statistical tests were two sided. We observed no overall association between plasma cysteinylglycine and invasive breast cancer risk. However, higher cysteinylglycine levels were marginally associated with an increased risk of breast cancer in the high oxidative stress groups. Women in the highest quintile group of cysteinylglycine relative to the lowest group had multivariate RRs (95% CIs) of 1.64 (1.01-2.66; P(trend) = 0.04) in the vitamin E placebo group, 2.51 (1.01-6.24; P(trend) = 0.07) in the high alcohol intake group (>or=9 g/day), and 1.66 (0.97-2.84; P(trend) = 0.03) in the overweight and obese group. Our findings suggest that women who are susceptible to experiencing oxidative stress may be at a greater risk for developing breast cancer.

Topics: Alcohol Drinking; Breast Neoplasms; Carcinoma, Ductal, Breast; Case-Control Studies; Dipeptides; Female; Humans; Middle Aged; Obesity; Oxidative Stress; Peptide Fragments; Postmenopause; Prospective Studies; Receptors, Antigen, T-Cell; Risk Factors; Vitamin E