A bioactive probe for glutathione-dependent antioxidant capacity in breast cancer patients: Implications in measuring biological effects of arsenic compounds

Abstract

Introduction Glutathione, a major cellular non-protein thiol (NPSH), serves a central role in repairing damage induced by cancer drugs, pollutants and radiation and in the detoxification of several cancer chemotherapeutic drugs and toxins. Current methods measure glutathione levels only, which require cellular extraction, rather than the glutathione recycling dependent antioxidant activity in intact cells. Here, we present a novel method using a bioactive probe of the oxidative pentose phosphate cycle, termed the OxPhos™ test, to quantify glutathione recycling dependent antioxidant activity in whole blood and intact human and rodent cells without the need for the isolation and cytoplasm extraction of cells. Methods OxPhos™ test kit (Rockland Immunochemicals, USA), which uses hydroxyethyldisulfide (HEDS) as a probe for the oxidative pentose phosphate cycle, was used in these studies. The results with OxPhos™ test kit in human blood and intact cells were compared with total thiol and high pressure liquid chromatography/electrochemical detection of HEDS metabolism. Results The OxPhos™ test measured glutathione-dependent antioxidant activity both in intact human and rodent cells and breast cancer patient’s blood with a better correlation coefficient and biological variability than the thiol assay. Additionally, human blood and mammalian cells treated with various arsenicals showed a concentration-dependent decrease in activity. Discussion The results demonstrate the application of this test for measuring the antioxidant capacity of blood and the effects of environmental pollutants/toxins. It opens up new avenues for an easy and reliable assessment of glutathione-dependent antioxidant capacity in various diseases such as stroke, blood borne diseases, infection, cardiovascular disease and other oxidative stress related diseases and as a prognostic indicator of chemotherapy response and toxicity. The use of this approach in pharmacology/toxicology including screening drugs that improve the glutathione-dependent antioxidant capacity and not just the glutathione level is clinically relevant since mammalian cells require glutathione dependent pathways for antioxidant activity.

Sub-Emetic Toxicity of Bacillus cereus Toxin Cereulide on Cultured Human Enterocyte-Like Caco-2 Cells

“…Increased cathepsin D activity is observed in carcinomas compared to in normal tissues and may play a role in tumor growth and metastasis [ 71 , 72 ]. GSTs are enzymes considered as dedifferentiation markers [ 73 ] and are also upregulated in breast cancer tissue and in the distal colon, which is the site with the highest incidence of colorectal cancer [ 74 , 75 ]. Furthermore, Rho-GDI has been upregulated in hepatic cancer cells [ 76 ].…”

Effect of Arsenite on Nitrosative Stress in Human Breast Cancer Cells and Its Modulation by Flavonoids

“…In this regard, the MCF-7 line showed poor ability to counteract redox imbalance (20). Also, As impaired antioxidant defence due to GGT inhibition and glutathione depletion, a key enzyme for breast cancer viability and resistance (11,21). On the contrary, GGT is overexpressed in the ZR-75-1 line (2), which could restore efficiently redox balance after recovery.…”

“…Thus, RNS/RSS balance might be decisive for antioxidant and cytoprotective effects of NO and GSH, respectively, with their reactive derivatives possibly interacting each other forming S-nitroso-metabolites and reciprocally cancelling their oxidative potential. Consequently, GGT antagonism is an attractive molecular candidate to revert resistance to nitrosative/oxidative chemotherapy given its importance for cellular GSH restoration and cellular resistance (21).…”

Remodulating effect of doxorubicin on the state of iron-containing proteins, and redox characteristics of tumor with allowance for its sensitivity to cytostatic agents

“…Data exist that changes in iron metabolism appear at the early stages of malignant transformation and are enhanced in the process of forming more aggressive phenotype by cells. It has been established that the tumor creates a pool of decompartmentalized, reactive "free iron" (Fe 2+ ) possessing prooxidant properties by accumulating proteins attracted to iron depositing and transportation, that is ferritin (FR) and transferrin (Tr), as well as at the expense of decreasing its removal through ferroportin [8][9][10][11]. In turn, superoxide radicals affect, both directly and indirectly, the regulation of activity of matrix proteinases and activation of the processes of peroxide oxidation of lipids (POL) that results in degradation of the intercell matrix and desruption of membrane integrity.…”