Suppression of the Antioxidant System and PI3K/Akt/mTOR Signaling Pathway in Cisplatin-Resistant Cancer Cells by Quercetin.

We studied the effect of quercetin on ovarian adenocarcinoma SKOV-3 cell line and isogenic subline SKOV-3/CDDP resistant to the anticancer drug cisplatin. It was found that in resistant cells, quercetin in a concentration of 100 µM that causes a decrease in the cell viability suppressed the expression of genes encoding the key antioxidant enzymes (SOD2, CAT, GPX1, and HO-1), transcription factor Nrf2, and kinases of the PI3K/Akt/mTOR signaling pathway. In parental cells, quercetin, on the contrary, increased the expression of these genes. The results confirm the redox-dependent regulation induced by quercetin and its opposite nature in cisplatin-sensitive and cisplatin-resistant cancer cells.

Suppression of PI3K/Akt/mTOR Signaling Pathway and Antioxidant System and Reversal of Cancer Cells Resistance to Cisplatin under the Effect of Curcumin.

The effect of curcumin on the resistance of SKOV-3 human ovarian adenocarcinoma cells to cisplatin was studied. It was found that curcumin induced "reversal" of cancer cells resistance, which was associated with suppression of the expression of genes encoding the key antioxidant enzymes (SOD1, SOD2, CAT, GPX1, and HO-1) and transcription factor Nrf2 and a decrease in the expression of genes encoding kinases of the PI3K/Akt/mTOR signaling pathway. The obtained results confirm the role of redox-dependent regulation in the "reversal" of cancer cells resistance to cisplatin.

Glutathione Synthesis in Cancer Cells.

Tripeptide GSH is associated not only with the control and maintenance of redox cell homeostasis, but also with the processes of detoxification, proliferation, cell differentiation, and regulation of cell death. Disruptions in GSH synthesis and changes in the GSH/GSSG ratio are common for many pathological conditions, including malignant neoplasms. Numerous data indicate the importance of GSH and the GSH/GSSG ratio in the regulation of tumor cell viability, in the initiation of tumor development, progression, and drug resistance. However, control of the mechanism of GSH synthesis in malignant tumors remains poorly understood. This review discusses the features of GSH synthesis and its regulation in tumor cells. The role of GSH in the mechanisms of apoptosis, necroptosis, ferroptosis, and autophagy is considered.

Role of MicroRNAs in the Regulation of Redox-Dependent Processes.

Cellular redox homeostasis involves a combination of redox processes and corresponding regulatory systems and represents an important factor ensuring cell viability. Redox-dependent regulation of cellular processes is a multi-level system including not only proteins and enzyme complexes, but also non-coding RNAs, among which an important role belongs to microRNAs. The review focuses on the involvement of miRNAs in the redox-dependent regulation of both ROS (reactive oxygen species)-generating enzymes and antioxidant enzymes with special emphasis on the effects of miRNAs on redox-dependent processes in tumor cells. The impact of ROS on the miRNA expression and the role of the ROS/miRNA feedback regulation in the cell redox state are discussed.

Redox-Dependent Expression of Genes Encoding NADPH Oxidase 5 and the Key Antioxidant Enzymes during Formation of Drug Resistance of Tumor Cells to Cisplatin.

Expression of genes that plays a significant role in the control of cellular redox homeostasis was studied during the development of drug resistance of human ovarian adenocarcinoma SKOV-3 cells to cisplatin. It was found that the development of drug resistance was accompanied by enhanced expression of the genes encoding the key antioxidant enzymes (SOD2, CAT, GPX1, and HO-1) and transcription factor Nrf2, as well as reduced expression of the gene encoding NOX5 isoform of NADPH oxidase. The results testify to redox-dependent development of the adaptive antioxidant response as an important process in the mechanism of formation of resistance to cisplatin.

[Hepatic haemangioma as sistemic manifestation of rheumatoid arthritis].

This article presents the clinical data regarding to the incidence of hepatic haemangioma in rheumatoid arthritis (RA) patients. Haemangioma of the liver has been diagnosed by ultrasonography dramatically oftener in RA than in OA: in 8 from 37 RA pts and neither in 120 osteoarthritis pts. Hepatic haemangioma was associated with long standing erosive RA, extra-articular RA manifestations, high levels of rheumatoid factor and ACCP. Moreover in RA pts with hepatic haemangioma we revealed significantly raised levels of pro-inflammatory cytokines, which can impact on the angiogenesis in RA. Obtained clinical data may contribute in the understanding of liver vessels involvement in RA and pose the role of systemic connective tissue lesion and immune inflammation in this process.

Role of glutathione, glutathione transferase, and glutaredoxin in regulation of redox-dependent processes.

Over the last decade fundamentally new features have been revealed for the participation of glutathione and glutathione-dependent enzymes (glutathione transferase and glutaredoxin) in cell proliferation, apoptosis, protein folding, and cell signaling. Reduced glutathione (GSH) plays an important role in maintaining cellular redox status by participating in thiol-disulfide exchange, which regulates a number of cell functions including gene expression and the activity of individual enzymes and enzyme systems. Maintaining optimum GSH/GSSG ratio is essential to cell viability. Decrease in the ratio can serve as an indicator of damage to the cell redox status and of changes in redox-dependent gene regulation. Disturbance of intracellular GSH balance is observed in a number of pathologies including cancer. Consequences of inappropriate GSH/GSSG ratio include significant changes in the mechanism of cellular redox-dependent signaling controlled both nonenzymatically and enzymatically with the participation of isoforms of glutathione transferase and glutaredoxin. This review summarizes recent data on the role of glutathione, glutathione transferase, and glutaredoxin in the regulation of cellular redox-dependent processes.

[Hygienic assessment of waste of soda production].

The object of investigations was soda industry waste. Slimes are formed at slimes storage which occupy considerable areas and are considered to be the source of permanent impact on the hydrosphere objects. Slimes storage placement within settlement boundaries and water protection zone of large watercourses leads to the deterioration of sanitary, hygienic and environmental situation and to the rising of risks to health of communities. Waste processing with getting new materials on the base of soda industry waste with wide application is seems to be one of the way for problem solving. It is essential to take into account sanitary and hygienic characteristics of slimes within justifying possible directions of its use. Thus, researches concerning assessment of physical, chemical and toxicological waste characteristics are considered to be actual. The aim of researches is to examine physical, chemical and toxicological characteristics of soda production slimes for justifying directions of its use including delivery of new materials respondent to the all regulatory sanitary and hygienic requirements. Experimental investigations of assessment physical, chemical and toxicological characteristics of slimes were carried out according to standard methods. Within assessment of toxicological slimes characteristics the following test-objects were used: Ceriodaphnia affinis, Paramecium caudatum. As a result of investigations watered slime samples were determined to be referred to the 4th hazard level (low-hazard) waste; samples with preliminary mechanical dehydration are referred to the 5th hazard level (practically nonhazardous) waste for environment. These are correspond to the 3rd and 4th hazard level according to sanitary regulations, respectively.

Expression of peroxiredoxin 1, 2, 3, and 6 genes in cancer cells during drug resistance formation.

We studied the expression of peroxiredoxin genes (PRDX1, PRDX2, PRDX3, and PRDX6) in human erythroleukemia K652, human breast carcinoma MCF-7, and human ovarian carcinoma SKOV-3 cells during cisplatin resistance development. It was found that drug resistance formation was accompanied by a significant increase in the expression of PRDX1, PRDX2, PRDX3, PRDX6 genes in all cancer cell strains, which confirms the important contribution of redox-dependent mechanisms into the development of cisplatin resistance of cancer cells.

Expression of genes of glutathione transferase isoforms GSTP1-1, GSTA4-4, and GSTK1-1 in tumor cells during the formation of drug resistance to cisplatin.

We studied the expression of genes encoding glutathione-S-transferase isoforms GSTP1-1, GSTA4-4, and GSTK1-1 during the development of the resistance of human erythroleukemia (K562), mammary adenocarcinoma (MCF-7) and ovary adenocarcinoma (SKOV-3) cells to cisplatin (CDDP). It was found that drug resistance development in all three strains of tumor cells is associated with significant increase in hGSTP1 and hGSTA4 gene expression, whereas increased hGSTK1 gene expression was detected only in resistant K562/CDDP and MCF-7/CDDP cells.

[Current views on antioxidative activity of glutathione and glutathione-depending enzymes].

Reduced glutathione (GSH), gamma-glutamyl-L-cysteineglycine, is a tripeptide widespread in plants, animals, and man as a low-molecular weight SH-containing compound. This review presents results of published and original studies concerned with the synthesis and the role of glutathione and glutathione-dependent enzymes in antioxidative processes, such as maintenance and regulation of cell status, glutathionilation and deglutathionilation, redox-dependent signaling, and apoptosis.

Involvement of thio-, peroxi-, and glutaredoxins in cellular redox-dependent processes.

Among the key antioxidant enzymes, thioredoxin and glutaredoxin systems play an important role in cell defense against oxidative stress and maintenance of redox homeostasis owing to the regulation of thiol-disulfide exchange. The thioredoxin isoforms Trx1 (cytoplasmic form) and Trx2 (mitochondrial form) can reduce inter- and intramolecular disulfide bonds in proteins, in particular, in oxidized peroxiredoxins, which disrupt organic hydroperoxides, H2O2, and peroxynitrite. NADPH-dependent thioredoxin reductase, which reduces a broad range of substrates including oxidized form of thioredoxin, can also directly reduce lipid hydroperoxides, H2O2, and dehydroascorbic and lipoic acids. Glutaredoxin, whose major isoforms in mammals are Grx1, Grx2, and Grx5, as well as thioredoxin, catalyzes S-glutathionylation and deglutathionylation of proteins to protect SH-groups from oxidation and restore functionally active thiols. However, in contrast to thioredoxin, glutaredoxin reduces GSH-mixed disulfides and catalyzes the reaction not only via a dithiol mechanism but also via monothiol reduction. In addition to the role in cellular antioxidant defense, all of the reviewed redox proteins (thioredoxin, thioredoxin reductase, peroxiredoxin, and glutaredoxin) have a number of significant functions required for cell viability: they regulate transcription factor activities, play the role of growth factors, serve as enzyme cofactors, take part in regulation of cell cycle, and are involved in antiapoptotic mechanisms.

[Why does iron abrogate the cytotoxic effect of S-nitrosothiols on human and animal cultured cells?].

It was found that dinitrosyl iron complexes (DNIC) with thiol-containing ligands (cysteine or glutathione) of concentrations up to 1 mM produce no cytotoxic effect on cultured cells from human milk gland carcinoma (MCF-7). The cytotoxic action on MCF-7 cells was produced by S-nitrosocysteine: at a concentration of 1 mM, it induced the death of 50% cells. A more stable S-nitrosothiol, S-nitrosoglutathione, did not produce any cytotoxic effect at the same concentration. It is assumed that the negative action of nitrosocysteine is due to its rapid degradation, which results in the accumulation of large amounts of free NO molecules followed by their oxidation by superoxide ions to peroxynitrite, an efficient inhibitor of metabolic processes. These processes seem to be not characteristic of the more stable S-nitrosoglutathione. The cytotoxic effect of nitrosocysteine was completlly abrogated by the addition of 0.2 mM ferrous citrate complex to the medium. When S-nitrosoglutathione NO (0.5 mM) or S-nitrosoglutathione (0.5 mM) + Fe(2+)-citrate (0.2 mM) were added to the medium, protein-bound dinitrosyl iron complexes formed with the involvement of endogenous or exogenous iron were detected in cells. The amount of the complexes in the presence of exogenous iron increased four times, reaching the value of 1.6 nmole/5 x 10(6) cells. Therefore, it was proposed that the blockade of the cytotoxic action of S-nitrosoglutathione by iron complexes is due to Cys-NO transformation of S-nitrosocysteine into dinitrosyl iron complexes. The high stability of these complexes ensures only a gradual accumulation of nitric oxide in cells.

[Oxidative stress and oxygen status in ischemic stroke].

A dynamic assessment of oxygen status of the arterial blood, activity of antioxidant system enzymes (AOS), succinatedehydrogenase (SDG), mitochondrial alpha-glycero-phosphate-dehydrogenase (alpha-GPDH) and alkaline phosphatase (AP) as well as concentrations of reduced glutathione (GSH) and secondary products of lipid peroxidation reacting with thiobarbituric acid (PLPRTA) has been carried out in patients at the acute stage of ischemic stroke of hemispheric location. Relative hyperoxia as a result of the hyperventilation syndrome was mostly pronounced on day 1 and 3. At the same time, a reduced activity of AOS system and an increase of PLPRTA concentration have been observed from the 1st day after stroke. There were also a decrease of the SDG activity and a marked (2,8 fold) increase of the alpha-GPDH activity as compared to the controls. A decrease of the AP leukocyte activity in the peripheral blood to day 7 after stroke makes possible a prognosis of good functional rehabilitation to the 21st day of the disease. Therefore, the results of the study suggest that the development of oxidative stress in patients with ischemic stroke is caused by tprimary disruption of bioenergetic processes during the reduction of AOS activity.

Expression of genes for thioredoxin 1 and thioredoxin 2 in multidrug resistance ovarian carcinoma cells SKVLB.

The expression of genes for thioredoxin isoforms Trx1 and Trx2 was studied in sensitive SKOV-3 and resistant SKVLB human ovarian carcinoma cells. The development of doxorubicin resistance was accompanied by a significant increase in the expression of TRX1 gene and less pronounced increase in TRX2 gene expression.

Expression of genes for redox-dependent glutathione S-transferase isoforms GSTP1-1 and GSTA4-4 in tumor cell during the development doxorubicin resistance.

Expression of genes for redox-dependent glutathione S-transferase isoforms GSTP1-1 and GSTA4-4 in tumor cells K562, MCF-7, and SKOV-3 was studied during the development of resistance to doxorubicin. It was found that the development of resistance was accompanied by predominant increase in the expression of hGSTP1 gene in MCF-7 cells, and hGSTA4 gene in resistant K562/DOX and SKVLB cells.

Changes in expression of genes encoding antioxidant enzymes, heme oxygenase-1, Bcl-2, and Bcl-xl and in level of reactive oxygen species in tumor cells resistant to doxorubicin.

The relationship between expression of genes encoding key antioxidant enzymes, heme oxygenase-1, Bcl-2, and Bcl-xl and change in production of reactive oxygen species (ROS) resulting from development of resistance of cancer cells K562, MCF-7, and SKOV-3 to the prooxidant chemotherapeutic agent doxorubicin (DOX) has been studied. Significant increase in mRNA level and activity of Mn-superoxide dismutase (Mn-SOD), catalase, and selenium-dependent glutathione peroxidase-1 (GPx-1) and reduced ROS level was found in resistant K562/DOX and SKVLB cells. In contrast, no change in ROS level was observed in MCF-7/DOX cells in parallel with decrease in Mn-SOD and catalase mRNAs and corresponding activities concurrently with high increase in GPx-1 mRNA and activity. As a result of the development of resistance, a similarity was found between the change in ROS level and the change in ho-1 and bcl-2 gene expression, whereas elevation of bcl-xl gene expression was observed in all three types of resistant cells. Particular features of development of adaptive antioxidant response as well as redox-dependent change in bcl-2 gene expression under formation of DOX resistance of cancer cells of different genesis are discussed.

[The treatment of trophic ulcers of venous etiology from the standpoint of evidence-based medicine. Review of literature].

Presented herein is a review of the modern world literature devoted to the pressing problem of phlebology--the treatment of trophic ulcers. In the given review all the available data on the modern treatment methods for trophic ulcers, resting on the criteria of evidence-based medicine (EBM), are systematized. Proceeding from these data we have evaluated the efficacy and safety of different approaches to the treatment of trophic ulcers and created the diagnostic and treatment algorithm for patients suffering from the pathology in question. The literature review, resting on the general criteria of evidence-based medicine, has demonstrated that the main current trends in the management of venous ulcers are moist healing, compression therapy, and surgical treatment. However, despite this fact there is a number of unsolved problems concerned first of all with the creation of the integral diagnostic and treatment program for patients with venous ulcers, based on the significant statistical data.

[Changes in the free-radical state and level of free iron during the formation of drug resistance in tumor cells].

The development of resistance of K562 human erythroleukemia cells to doxorubicin, a widely used antitumor antibiotic with the prooxidant action, leads to changes in the free-radical state of cells. It has been found that the formation of superoxide anion in resistant cells decreases. The introduction of doxorubicin to the culture medium induced a considerably lesser increase in the formation of O2*- in resistant cells compared to sensitive cells. At the same time, a strong decrease in the ESR signal of semiquinone type with a g-factor of 2.006 was observed in a culture of resistant cells grown in the absence of doxorubicin as compared with sensitive cells grown under similar conditions. At the same time, a decrease in the level of paramagnetic nitrosyl complexes of nonheme iron in resistant cells was recorded, indicating a decrease in the content of free nonheme iron as a result of the formation of drug resistance. In addition, a decrease in the level of mRNA of the transferrin receptor in resistant cells was found by the RT-PCR. These data indicate the development of a coodinated redox-dependent adaptive response, which makes itself evident as a suppression of free radical processes during the formation of resistance of K562 cells to doxorubicin.