The anticarcinogenic potential of milk fat

INTRODUCTION AND OBJECTIVE

The anticarcinogenic potential of milk fat can be attributed to its antioxidant, anti-inflammatory, immunostimulatory properties as well as the presence of compounds with antimutagenic effects. In view of the high incidence of cancer the aim of this article was to review the literature concerning the biological activity of milk fat components.

BRIEF DESCRIPTION OF THE STATE OF KNOWLEDGE

Conjugated linoleic acid (CLA), coenzyme Q10, phospholipids, β-carotene, and vitamins A, D and E play an important role in the pro-oxidant/antioxidant homeostasis. The anti-inflammatory properties of milk fat can be attributed to the presence of phospholipids and short- and medium-chain saturated fatty acids. Conjugated linoleic acid has immunostimulatory properties, and it influences the proliferation and activity of lymphocytes and macrophages. Saturated (C10 and C12) and unsaturated (C18) fatty acids, as well as sphingolipids, exert bactericidal effects in the gastrointestinal tract. Vaccenic acid, CLA and sphingomyelin possess antimutagenic and anticarcinogenic properties. Butyric acid promotes the apoptosis of cancer cells in the liver, and delivers positive effects in the treatment of breast and colorectal cancer. Alkylglycerols activate macrophages, stimulate phagocytosis and, most importantly, the apoptosis of cancer cells.

CONCLUSIONS

The health benefits of milk fat are not fully exploited due to its low consumption. Therefore, only some epidemiological studies have shown a negative correlation between the consumption of high-fat dairy products and the incidence of cancer. More research is needed involving human clinical trials to allow a better understanding of the anticancer biochemistry related with milk fat compounds.

Effect of different concentrations of oxygen on expression of sigma 1 receptor and superoxide dismutases in human colon adenocarcinoma cell lines

CONTEXT

Tumor cells due to distance from capillary vessels exist in different oxygenation conditions (anoxia, hypoxia, normoxia). Changes in cell oxygenation lead to reactive oxygen species production and oxidative stress. Sigma 1 receptor (Sig1R) is postulated to be stress responding agent and superoxide dismutases (SOD1 and SOD2) are key antioxidant enzymes. It is possible that they participate in tumor cells adaptation to different concentrations of oxygen.

OBJECTIVE

Evaluation of Sig1R, SOD1, and SOD2 expression in different concentrations of oxygen (1%, 10%, 21%) in colon adenocarcinoma cell lines.

MATERIALS AND METHODS

SW480 (primary adenocarcinoma) and SW620 (metastatic) cell lines were cultured in standard conditions in Dulbecco's modified Eagle's medium for 5 days, and next cultured in Hypoxic Chamber in 1% O2, 10% O2, 21% O2. Number of living cells was determined by trypan blue assay. Level of mRNA for Sig1R, SOD1, and SOD2 was determined by standard PCR method. Statistical analysis was conducted using Statistica 10.1 software.

RESULTS

We observed significant changes in expression of Sig1R, SOD1, SOD2 due to different oxygen concentrations. ANOVA analysis revealed significant interactions between studied parameters mainly in hypoxia conditions in SW480 cells and between Sig1R and SOD2 in SW620 cells. It also showed that changes in expression of studied proteins depend significantly on type of the cell line.

CONCLUSION

Changes of Sig1R and SOD2 expression point to mitochondria as main organelle responsible for survival of tumor cells exposed to hypoxia or oxidative stress. Studied proteins are involved in intracellular response to stress related with different concentrations of oxygen.

[The role of flavonoids in the modulation of inflammation]

Chronic inflammation in the body leads to the formation and development many diseases, e.g. atherosclerosis, diabetes, neurodegenerative diseases or cancer and others. Therefore, the search for new and safe compounds of plant origin having antiinflammatory activity. They include, among others, naturally occurring in the diet of human - flavonoids. Anti-inflammatory effects of these compounds is due to their antioxidant properties, ability to inhibit enzymes involved in the metabolism of eicosanoids and proinflammatory molecules and modulate the expression of certain proinflammatory genes. Intensive studies in vitro and in vivo antiinflammatory activity of flavonoids are important not only because of the knowledge of the mechanisms of action of these compounds, but also to develop a new class of safe anti-inflammatory drugs of plant origin. This should bring prophylactic and therapeutic benefits. A diet rich in flavonoid compounds and/or supplementation with these compounds not only improve the efficiency of prevention of nutrition, but also complement the medical therapy of many diseases.

[The level of superoxide dismutase expression in primary and metastatic colorectal cancer cells in hypoxia and tissue normoxia]

Superoxide oxidase (SOD) is a key antioxidant enzyme protecting cells against oxidative stress, which might induce cancerogenesis. In tumor cells SOD influences the level of the reactive oxygen species (ROS) allowing for survival and proliferation. High rate of cells proliferation in tumor leads to their temporary hypoxia due to lower rate of angiogenesis. Therefore during tumor development, cancer cells function in conditions of hypoxia or tissue normoxia.

AIM

The aim of study was to evaluate of SOD isoenzymes (SOD1 and SOD2) expression level in cell lines of primary (SW 480) and metastatic (SW 620) colorectal cancer, cultured in hypoxia (1% oxygen), tissue normoxia (10% oxygen), and atmospheric normoxia (21% oxygen).

MATERIALS AND METHODS

Cells were cultured in MEM medium in different oxygen concentrations (1%, 10%, 21%) in hypoxic chamber with oxygenation regulator. The number of living cells in lines SW 480 and 620 was determined by trypan blue method. Expression of SOD1 and SOD2 at the mRNA level was determined by RT-PCR and PCR.

RESULTS

In both studied cell lines (SW 480 and SW 620), the number of living cells (viability) was increased in hypoxia and atmospheric normoxia. The expression level of SOD1 and SOD2 in studied cell lines was different. The lowest level of expression of both SOD isoenzymes was observed in hypoxia. In conditions of atmospheric normoxia the expression level of SOD1 in SW480 cell line was increased, and similar in SW620 cell line comparing to tissue normoxia. Whereas the SOD2 expression level in atmospheric normoxia conditions in both cell lines was significantly increased. Observed differences were statistically significant (p ≤ 0,05).

CONCLUSIONS

The profile of expression of SOD1 and SOD2 in cell lines SW480 and SW620 indicates differentiated response of tumor cells depending on access to oxygen. Low level of SOD isoenzymes expression in SW480 and SW620 cells in hypoxia indicates decreased production of ROS. Differences of SOD isoenzymes expression level in tissue normoxia indicate their compensatory action, allowing to maintain the balance between O₂- removal and H₂O₂production in studied tumor cells. In atmospheric normoxia conditions increased expression level of SOD1 and SOD2 observed in studied cell lines points to oxidative stress.

[Milk fat - the only existing for any reason]

The milk fat is characterized by an unique composition (over 400 different fatty acids) and stereospecific structure of triglycerides, similar to human milk fat. Almost entirely it is encircled by envelopes made of phosphorolipids and proteins, making the fat stabile oxidatively and resistant for hydrolysis. The envelope of fatty spherule ensures stability of emulsions, as well, as very high extent of dispersion, making milk fat the most easily digested fat in human diet. Phosphorolipids, proteins, peptides and numerous enzymes present inside the envelope are characterized by very high biological activity. All - without any exception - components of milk fat, also saturated fatty acids considered as atherogenic, are extremely biologically active. Lipophylic antioxidants (conjugated linoleic acid, α-tocopherol, vitamin A and β-carotene, coenzyme Q10, vitamin D3 and phospholipids) are efficient in inhibition of processes of lipids peroxidation within cell structures and of plasma lipoproteins. The unique components of milk fat i.e. conjugated linoleic acid and ether lipids (alkyloglyceroles and alkyloglycerophospholipids) possess the broadest spectrum of pro-health activity.

[The level of lipid peroxidation in milk replacer formulas for initial feeding of infants]

The products of lipids oxidation: peroxides, hydroxides, aldehydes, ketones, esters, alcohols and others show harmful activity against human organism. Presence of the compounds in baby's and children's food creates potential health hazard. Many of them cause infant's and children's diarrhoea, also, negatively influence development of nervous system, show cytotoxic, mutagenic and cancerogenic activity (e.g. malonicdialdehyde, 4-hydroxynonenal and others).

AIM

The aim of the work was to assess the level of lipids peroxidation in milk substitute preparations for initial stage baby feeding, before their end of shelf-life.

MATERIALS AND METHODS

The level of lipids peroxidation measured as TBARS (thiobarbituric acid reactive substances) concentrations was determined in 6 available on the Polish market milk substitute infant formulas. The determinations was carried out before the end of the shelf-life after 1,2,3,6,9 and 12 months after purchase. The level of lipid peroxidation was also determined after 3-4 and 21 days post opening.

RESULTS

TBARS content in the infants food ready to be eaten depended on the time of preparation storage. The highest level of lipids peroxidation was observed in all the studied food after 12 months of storage and after 21 days after opening of the hermetical wrapping. Various level of lipids peroxidation in milk substitutes for infant nutrition resulted from different amounts and quality of plant oils used in production (different content of mono- and polyunsaturated fatty acids, presence of lack of linoleic and α-linolenic acids).

[Calcium--essential for everybody]

Calcium regulates majority of metabolic processes within human organism and its optimal intake decreases risk of metabolic illnesses conditioned by diet. Deficiency of calcium results in higher body max index, increase risk of insulin resistance, diabetes type 2 and osteoporosis. Diet delivering full calcium load diminished impendency of hypertension; calcium regulates tension of smooth muscles of blood vessels, limits neurotransmitters activity and also diminish hazardous activity of sodium chloride. Anticancerogenic activity of calcium results from formation insoluble bile acids and fat acids salts, and most of all, from inhibition of intestine mucosa cells hyper proliferation. Due to presence of vitamin D3, CLA, proteins and bioactive peptides emerging from them, milk is more efficient in prophylaxis of diet conditioned illnesses than calcium supplements. Efficiency of milk and dairy products in treatment of obesity, sclerosis and hypertension has been proved by DASH diet.

Multiple protective functions of sigma1 receptor

The Sigma Receptor 1 (sig-1R) is a protein present in numerous normal tissues, such as brain, retina, lens, liver, lung, heart, but also in many tumor lines. Its amino acid sequence is homologous to fungal C-8,7 sterol isomerase, but it has no known homology with mammalian proteins and does not possess sterol isomerase activity. It is localized in plasma and ER membranes, and its exact function is not clarified as of yet. Last reports point to its participation in regulation of ionic channels activity, particularly calcium channels. Application of numerous synthetic ligands of sigma1 receptor provided means to study its protective effects and metabolic functions in different tissues. This review describes influence of sigma1 receptor on various aspects of cellular metabolism, such as calcium signalling, mitochondrial functions, oxidative stress, survival and apoptotic pathways, and tumor cells proliferation.

[Controversies around diet proteins]

Critical theories regarding proteins of anima origin are still and still popularized, though they are ungrounded from scientific point of view. Predominance of soya proteins over the animal ones in relation to their influence on calcium metabolism, bone break risk or risk of osteoporosis morbidity has not been confirmed in any honest, reliable research experiment. Statement, that sulphur amino acids influence disadvantageously on calcium metabolism of human organism and bone status, is completely groundless, the more so as presence of sulphur amino acids in diet (animal proteins are their best source) is the condition of endogenic synthesis of glutathione, the key antioxidant of the organism, and taurine stimulating brain functioning. Deficiency of proteins in the diet produce weakness of intellectual effectiveness and immune response. There is no doubt that limitation of consumption of animal proteins of standard value is not good for health.

Altered expression level of Sigma1 receptor gene in human colorectal cancer

Nonopioid Sigma1 receptor (Sig1R) influences numerous metabolism functions including regulation of ion channels, reaction on stress and response to growth signals. Due to this influence, Sigma1 receptor ligands show anti-proliferative and cytotoxic action on tumor cells. Additionally its increased level is observed in some types of tumors. Colorectal cancer is one of the most common cancers worldwide and its clinical development is well described. The aim of the study was evaluation of Sigma1 receptor mRNA expression level in human colorectal cancer and colorectal cancer liver metastases at different stages of tumor development. The mRNA was isolated from 30 patients: 18 with colorectal cancer (CRC) and 12 with colorectal cancer liver metastases (CRCLM). The cDNA of Sig1R gene was amplified by polymerase chain reaction using specific primers. The level of Sig1R mRNA expression was determined by measurement of optical density. Sig1R expression level was increased in CRC and CRCLM. The highest level of Sig1R mRNA was observed in UICC stage III. We also showed significant interactions of UICC stage and tumor localization with Sig1R expression level. There were no interactions between UICC stage and age of patients, although we observed significantly decreased level of Sig1R mRNA in older patients. Clinical advancement stage, localization of tumor and age of patients seems to be an important factors influencing Sigma1 receptor expression level. It is probably due to double nature of Sig1R action - in certain conditions it could act pro- or antiapoptotic. This action might depend on Sig1R activity resulting from its expression level.

[Anticancer activity of flavonoids]

On the basis of previous in vitro, in vivo and epidemiological studies was found that flavonoids among their many biological and pharmacological properties have a great anticancer potential. High intake of foods rich in these compounds, mainly vegetables and fruits is associated with a low rate of cancer in humans. Flavonoids may act at different stages of carcinogenesis: initiation, promotion and progression. The complex mechanism of antitumor action include: antioxidant activity, carcinogens inactivation, antiproliferation, block of the cell cycle, induction of apoptosis and differentiation, inhibition of angiogenesis and elimination of drug resistance. With multidirectional action in carcinogenesis and targeting its action only on cancer cells, it is suggested that these compounds may give a new perspective of their use in prevention and therapy of cancer.

[Milk fat in prophylaxis of cancer diseases]

Milk fat is characterized by extensive pro-health activity. Its unique components, such as: short chain saturated fatty acids, conjugated linoleic acid (CLA), vaccenic acid, ether lipids (alkiloglicerols and alkiloglicerophospholipids), 13-methyltetradecanic acid and bioactive components of antioxidative activity, are important in prophylaxis, and even in therapy of cancer diseases. Advantageous influence to maintain pro- and antioxidative balance of organism is revealed by the components of milk fat: conjugated linoleic acid, vitamins A and E, and coenzyme Q10. Moreover, vitamin D3, phospholipids, ether lipids, cholesterol and 13-methyltetradecanic acid also reveal antioxidative activity.

The effects of sodium diethyldithiocarbamate in fibroblasts V79 cells in relation to cytotoxicity, antioxidative enzymes, glutathione, and apoptosis

Sodium diethyldithiocarbamate (DETC) is the main metabolite of disulfiram. Recently, we reported that mechanism of disulfiram cytotoxicity in V79 cells might be partially connected with thiol redox-state imbalance. Here, we examined the effect of DETC on the level of intracellular glutathione (GSH), protein oxidation (measured as PC—protein carbonyl content), lipid peroxidation (measured as TBARS—thiobarbituric acid reactive substances), antioxidant enzymatic defense, as well as on apoptosis. We used V79 Chinese hamster fibroblasts cells with and without modulated glutathione (GSH) level by N-acetyl-l-cysteine (NAC). We showed that treatment with DETC at concentrations that cause a moderate increase in thiol-state imbalance but not cell death stimulates oxidative stress measured as increased level of PC and TBARS, adaptive response of GSH-related enzymes and apoptosis. Our results show that cellular effects of DETC are partially attributable to the initial redox cellular state, since the increase of GSH level by NAC pre-treatment prevented the observed changes.

[The food cholesterol controversy]

Arteriosclerosis of blood vessels, the main cause of heart attack and stroke, is a disease of multifactor pathogenesis. Multiple experimental, clinical and epidemiologic studies indicate that free radicals and lipid oxidation products take part in aterogenesis process. Homocysteine possess also cytotoxic activity leading to degradation of elastine of internal membrane of blood vessels. Deficiency of vitamin folic acid, B12 and B6 cause homocysteine accumulation in human organism. Identifying the arteriosclerosis with oxidation of LDL-cholesterol results with faulty conclusions. Metabolism of cholesterol in human organism depends on content of n-6 and n-3 polyunsaturated fatty acids, phospholipids, fitosterols, food fiber, Lactobacillus and antioxidants in the diet. In aterogenesis antioxidant defficiency, especially long-lasting ones, are more important then amount of fat itself. Considering cholesterol intake with average food and its absorption amounting 25-30%, one can conclude that amount of cholesterol in intestine originates in 90% from liver synthesis, which is excreted with bile, and in more than ten percent--from food. This is why reduction of cholesterol intake with food only little improves blood lipid indexes.

[Flavonoids in the prevention and treatment of cardiovascular diseases]

Flavonoids are plant components of the diet. Their daily intake is about 1 g. In Poland the main source of flavonoids is tea, apples and onions. These compounds are characterized by a variety of biological activities and pharmacological effects. Especially important for human health are their antioxidant properties. This paper presents the current state of knowledge on the role and importance of flavonoids in the prevention of the initiation and development of cardiovascular diseases. Epidemiological observations, clinical research, in vitro and in vivo experimental studies clearly show a protective effect of flavonoids on the cardiovascular system. Their beneficial effects on the cardiovascular system involve the inhibition of low density lipoprotein (LDL) oxidation, the reduction of blood vessels permeability, antiplatelet and anti-inflammatory activity, and hypotensive and direct vasodilator action. Biological potential of flavonoids (especially the antioxidant activity) indicates the possibility of their use in primary and secondary prevention of atherosclerosis and its clinical consequences (heart attack, stroke, and others) as a safe potential therapeutic agents.

[Spuriously unhealthy animal fats]

Animal fats are generally considered as a source of saturated fatty acids and cholesterol, identified with arteriosclerosis and its clinical complications (cardiovascular diseases with heart attack, stroke, cerebral claudication). The real reason of arteriosclerosis are inflammation states of blood vessel endothelium caused by oxidative stress, hiperhomocysteinemia, hipertrigliceridemia, presence of artificial trans isomers and excess of eicosanoids originated from poliunsaturated fatty acids n-6. Present status of science proves that both saturated fatty acids and cholesterol present in animal food can not cause inflammation state. Moreover, animal fats are source of antioxidants active both in food and in human organism. Due to high oxidative stability animal fats do not make threat to human health. Milk fat, though high content of saturated fatty acids and cholesterol, possesses comprehensive pro-health activity--against arteriosclerosis and cancerogenesis.

[Spuriously healthy plant fats]

Since long plant fats are considered by nutritionists, dieticians and doctors, as main source of essential unsaturated fatty acids) n-6 and n-3 in human diet. On the market there is plenty of oils that can be consumed directly or used to frying. Last four decades consumption of oils increased several times due to stimulated by advertisement popularization of their pro-health activity. Plant oils supply mostly multi unsaturated fatty acids n-6 excess of which disadvantageously influence human health. Determinations of changes of oxidative stability of plant fats (during processing and storage) proved that consumption of oxidation products of fatty acids and sterols may be a reason of various diseases. Both epidemiologic and clinic studies indicated that if plant fats (both oils except this from olives and margarines) have possessed pro-health properties, their several times increased consumption would liquidate the problem of arteriosclerosis and its clinical complications (heart attack, stroke). For the present, every second death in the industrial countries results from the cardiovascular disease. Morbidity of cancer is also increasing and of neurological and neurodegenerative diseases is growing up vigorously.

[Evaluation of beta2-microglobuline expression level in gastrointestinal tract tumors due to usefulness as a reference gene in PCR method]

Quantitative and semi-quantitative determination of gene expression by PCR plays an important role in studying of tumors initiation and progression mechanisms. Selection of appropriate reference gene is a critical factor influencing the results of gene expression analysis. One of the most commonly used reference genes in PCR is beta2-microglobuline (beta2-M). Recent studies showed however that expression of some common reference genes might be unstable, therefore it is necessary to verify again their usefulness. The aim of the study was to determine the level of beta2-M mRNA in normal and tumor tissues of gastrointestinal tract due to adequate selection of reference gene in gene expression studies.

MATERIAL AND METHODS

Samples were taken from 253 patients operated on for gastrointestinal tract tumors: 22 with oral cavity cancer, 12 with benign and 50 with malignant liver tumors, 86 with colorectal cancer, and 83 with metachronous metastases to liver. Also 56 patients with liver cirrhosis were studied, which was treated as pre-tumor state. Together 309 patients were studied. RNA was isolated from tissues by Chomczynski method. The expression level of 12-M was determined by reverse transcriptase PCR (RT-PCR) and given in terms of optical density values.

RESULTS

Expression of beta2-M was observed in all studied tissues. There were no differences between normal and tumor tissue. The level of expression of beta2-M was different due to type of studied tissue (oral cavity, liver, colon).

CONCLUSIONS

The lack of significant differences in beta2-M expression level in normal and tumor tissues indicated that beta2-M can be used as reference gene in studies of gene expression in gastrointestinal tract tumors. On the other hand differences of beta2-M expression level in different types of tissues point to its tissue specificity and suggest application in PCR of more than one reference gene.

[Lipid peroxidation level in gastrointestinal tract tumors]

Oxygen free radicals and their reactive derivatives participate in formation of chronic inflammation states, which facilitate development of gastrointestinal tract tumors. Oxidative stress is one of the main causes of damage to cell membranes in result of exacerbated lipid peroxidation process. End products of lipid peroxidation (aldehydes, organic peroxides) react with important biological macromolecules such as DNA and proteins, cause changes in cell membrane structure and properties leading to loss of its integrity. Intensification of the lipid peroxidation process is a factor which may also lead to a malfunction in the antioxidant barrier, which further weakens the defense of cells against oxygen free radicals and promotes the onset and development of cancer. The aim of the study was the determination of lipid peroxidation level in gastrointestinal tract tumors (stomach, liver, colon, and colorectal cancer to liver metastases).

MATERIAL AND METHODS

Materials for studies were obtained from 150 patients with gastrointestinal tract tumors: 10 with stomach cancer, 30 with malignant and benign liver cancers, 60 with primary colorectal cancer, and 50 with metachronous colorectal cancer liver metastases. We also investigated 25 patients with liver cirrhosis, which was treated as a pre-cancerous condition. In total, 175 patients were examined. Tumor specimens, and normal adjacent tissues (6-7 cm from the edge of the tumor), which served as control tissue in studies, were collected from patients (with their consent) during surgery. Additionally, liver specimens were collected from patients with liver cirrhosis. Lipid peroxidation level was determined spectrophotometrically as a concentration of final lipid peroxidation products, which in reaction with tiobarbituric acid (TBA) form colour complex (thiobarbituric acid-reactive substances - TBARS).

RESULTS

The study showed the highest concentration of TBARS in benign, and the lowest in malignant liver tumors. Other types of gastrointestinal tumors studied, were characterized by similar levels of lipid peroxidation. TBARS concentration in these tumors was approximately 2-fold higher than in malignant liver tumors and much lower than in benign tumors. In all cancers of the digestive tract with the exception of malignant liver tumors increased level of TBARS was found, comparing with control tissue. The concentration of TBARS in cirrhotic liver was lower than in control. The level of lipid peroxidation in liver cirrhosis and malignant liver tumors was similar. There were no significant differences in TBARS concentration in the tumors of particular sections of the intestine and normal colon. The highest concentration of TBARS was found in G1 grade of colorectal cancer. In subsequent grades of cells differentiation (G2 and G3) its concentration was lower. The highest level of lipid peroxidation, expressed as the concentration of TBARS was found in the I stage of colorectal cancer clinical advancement. The significantly lowest concentration of TBARS was shown for stage II (UICC).

CONCLUSIONS

The level of lipid peroxidation in cancerous cells of gastrointestinal tract indicates increased oxidative stress. The changes of lipid peroxidation level--a marker of oxidative stress in gastrointestinal tumors appear to be closely associated with their development stages (liver cirrhosis/malignant liver cancer; colorectal cancer/colorectal cancer liver metastases) and are likely to create such conditions, in which cancerous cells may proliferate, undergo gradual dedifferentiation and malignancy, and generate metastases.

Protective effect of N-acetyl-L-cysteine against disulfiram-induced oxidative stress and apoptosis in V79 cells

This work investigated the effect of N-acetyl-L-cysteine (NAC) on disulfiram (DSF) induced oxidative stress in Chinese hamster fibroblast cells (V79). An increase in oxidative stress induced by DSF was observed up to a 200 μM concentration. It was evidenced by a statistically significant increase of both GSH(t) and GSSG levels, as well as elevated protein carbonyl (PC) content. There was no increase in lipid peroxidation (measured as TBARS). DSF increased CAT activity, but did not change SOD1 and SOD2 activities. Analysis of GSH related enzymes showed that DSF significantly increased GR activity, did not change Se-dependent GPx, but statistically significantly decreased non-Se-dependent GPx activity. DSF showed also pro-apoptotic activity. NAC alone did not produce any significant changes, besides an increase of GSH(t) level, in any of the variables measured. However, pre-treatment of cells with NAC ameliorated DSF-induced changes. NAC pre-treatment restored the viability of DSF-treated cells evaluated by Trypan blue exclusion assay and MTT test, GSSG level, and protein carbonyl content to the control values as well as it reduced pro-apoptotic activity of DSF. The increase of CAT and GR activity was not reversed. Activity of both GPx was significantly increased compared to their values after DSF treatment. In conclusion, oxidative properties are at least partially attributable to the cellular effects of disulfiram and mechanisms induced by NAC pre-treatment may lower or even abolish the observed effects. These observations illustrate the importance of the initial cellular redox state in terms of cell response to disulfiram exposure.

Evaluation of mutagenic activity of the organo-selenium compound Selol by use of the Salmonella typhimurium mutagenicity assay

We examined the mutagenic activity of the anti-oxidant Selol, an organo-selenium compound, by use of the Salmonella typhimurium mutagenicity assay (Ames test) with strains TA97a, TA98, TA100, TA 1535 and TA102 in the absence and in the presence of metabolic activation with an S9 fraction from Aroclor-induced rat liver. Doses were 330, 500, 1000 and 5000 microg per plate. Selol contains the element selenium (valency, +4) in its structure and it may have chemopreventive and anticancer activity. Selol was found to be non-toxic and non-mutagenic for test doses up to 5% per plate (which designates the declared content of Selenium (+4) as 5000 microg per plate) in all the S. typhimurium strains.

[Cadmium--element completely unnecessary for the organism]

Cadmium (Cd) is the main environmental pollutant. This metal presents a serious threat to the health of people and animals. The environmental risk can lead to the absorption of large quantities of cadmium and its toxic action on the organism. It adversely affects a number of organs in humans and animals, including the kidneys, liver, lungs, pancreas, and testis. The liver and kidneys, which are the primary organs involved in the elimination of this metal from the organism, are especially sensitive to its toxic effects. This paper presents the current state of knowledge related to the molecular mechanisms of the toxic action of cadmium in cells. Different mechanisms are discussed: the disruption of the cellular antioxidant system and decrease in thiol status, the generation of reactive oxygen species, inhibition of DNA repair and DNA methylation, the activation of cellular signals and protooncogenes, disruption of cell adhesion, cell damage leading to apoptosis, the promotion of cell proliferation, and the initiation of mutagenesis/carcinogenesis.

[Assessment of lipid peroxidation level in serum of patients with gastrointestinal tract tumors]

INTRODUCTION

Clinical and experimental studies indicate oxygen free radicals and their reactive derivatives participation in formation of chronic inflammation states, which facilitate gastrointestinal tract tumors development. During malignant changes formation in epithelium of gastrointestinal tract increased oxygen radicals generation initiates lipid peroxidation and DNA and proteins oxidation processes. Final lipid peroxidation products (saturated and unsaturated aldehydes) are highly reactive and characterized by greatly longer half life time than reactive oxygen species and capability to diffuse from places of their formation to distant cell areas. In cells they react with important biological macromolecules such as DNA and proteins causing their structural and functional damages. The effects of changes in cell membranes structure are increase in their permeability, depolarization, decrease of hydrophobicity and inhibition of enzymes, membrane channels and transporters. These changes lead to the loss of cell integrity.

STUDY AIM

Determination of lipid peroxidation level in blood serum patients with gastrointestinal tract tumors.

MATERIALS AND METHODS

Materials for studies were obtained from 170 patients with gastrointestinal tract tumors: 10 with stomach cancer, 20 with pancreatic cancer, 30 with primary liver cancer, 60 with primary colorectal cancer and 50 with metachronic colorectal cancer liver metastases. Blood was taken from patients 1 day before and 6 days after surgery. Control blood was obtained from 53 healthy blood donors. Lipid peroxidation level was determined spectrophotometrically as a concentration of final lipid peroxidation products, which in reaction with tiobarbituric acid (TBA) form colour complex (thiobarbituric acid-reactive substances, TBARS).

RESULTS

Higher lipid peroxidation level was observed in pre- and postoperative blood sera patients with gastrointestinal tumors in comparison to serum from healthy blood donors.

CONCLUSIONS

Increased lipid peroxidation level in peripheral blood of patients with gastrointestinal tract tumors is evidence of intensive oxidative stress and might indicate impairment of antioxidant defense mechanisms in organism.

Expression and activity of superoxide dismutase isoenzymes in colorectal cancer

The aim of the study was an evaluation of changes in protein level and activity of SOD isoenzymes, and the participation of AP-1 and NF-kappaB in subsequent stages of colorectal cancer development. Studies were conducted on 65 colorectal cancers. Controls were unchanged colon regions. Activity of SOD isoenzymes, lipid peroxidation level (TBARS), and protein level of SOD1, SOD2, AP-1 and NF-kappaB were determined. We found that the protein level and activity of SOD isoenzymes and protein level of AP-1 and NF-kappaB change in subsequent stages of clinical advancement of colorectal cancer, according to UICC (I-IV), and in grades of tumor cells differentiation (G(1)-G(3)). These results indicate adaptation of colorectal cancer cells to oxidative stress, and show that the observed changes of SOD activity and protein level depend on gradual progression of colorectal cancer, and suggest an impairment of processes regulated by AP-1 and NF-kappaB which are critical for tumor progression (proliferation, differentiation and apoptosis).

Expression and activity of superoxide dismutase isoenzymes in colorectal cancer

The aim of the study was an evaluation of changes in protein level and activity of SOD isoenzymes, and the participation of AP-1 and NF-kappaB in subsequent stages of colorectal cancer development. Studies were conducted on 65 colorectal cancers. Controls were unchanged colon regions. Activity of SOD isoenzymes, lipid peroxidation level (TBARS), and protein level of SOD1, SOD2, AP-1 and NF-kappaB were determined. We found that the protein level and activity of SOD isoenzymes and protein level of AP-1 and NF-kappaB change in subsequent stages of clinical advancement of colorectal cancer, according to UICC (I-IV), and in grades of tumor cells differentiation (G(1)-G(3)). These results indicate adaptation of colorectal cancer cells to oxidative stress, and show that the observed changes of SOD activity and protein level depend on gradual progression of colorectal cancer, and suggest an impairment of processes regulated by AP-1 and NF-kappaB which are critical for tumor progression (proliferation, differentiation and apoptosis).

[Cancer cells and oxidative stress]

Reactive oxygen species (ROS) formation are a constant element of a cell's oxygen metabolism. They are its normal products and in physiological concentrations they play important roles in a variety of cell processes. Disturbances in the balance between ROS formation and the efficiency of antioxidant mechanisms lead to oxidative stress. Oxidative stress causes damage to important macromolecules, such as DNA, proteins, and lipids. Growing evidence indicates the participation of ROS in the cancerous transformation of cells. Oxidative stress was also found in cancer cells, but the mechanisms responsible for its induction have not been definitively explained. It is known that they include inflammation and cytokine action, oncogenic signals, intensive metabolism related to constant proliferation, mutations in mitochondrial DNA, and malfunction in the respiratory chain. A high level of ROS in cancer cells may lead to a variety of biological responses, such as cell adaptation, increased proliferation rate, formation of DNA mutations and genetic instability, and resistance to some drugs used in anticancer therapy. Therefore, oxidative stress in cancer cells promotes tumor development, but it can also be useful in the search for new therapeutic strategies of cancer treatment.

[Activity of GSH-dependent enzymes in blood serum of patients with acute and chronic pancreatitis]

INTRODUCTION

Since one of the many proposed factors in the pathogenesis of acute and chronic pancreatitis is oxidative stress, the aim of the research was evaluation of antioxidant defense mechanisms, with particular emphasis on the role of reduced glutathione and GSH-dependent enzymes.

MATERIAL AND METHODS

The study involved a group of 35 patients with pancreatitis treated at the Clinic of General Surgery and Transplantation Medical University of Warsaw in the period from 2005 to 2007. This group consisted of 20 patients with mild symptoms (edema) of the form of acute pancreatitis and 15 patients with chronic pancreatitis, short duration of the disease. In all patients with acute and chronic pancreatitis qualified for the study were measured in serum markers of oxidative stress: concentrations of reactive thiobarbituric acid (TBARS), which determines the level of lipid peroxidation and reduced levels of glutathione (GSH) and activity of antioxidant enzymes: total glutathione peroxidase (cal. GSHPx), glutathione S-transferase (GST) and glutathione reductase (GSHR).

RESULTS

We found increased lipid peroxidation level, decreased level of GSH, and changes in activity of GSH-dependent enzymes in blood serum of patients with acute and chronic pancreatitis, compared to blood serum from healthy persons.

CONCLUSIONS

Obtained results indicate participation of oxidative stress in pathogenesis of those diseases, and systemic impairment of antioxidative mechanisms.

[Protein level of transcription factors AP-1 and NF-kappaB in selected human gastrointestinal tract tumors]

Transcription factors AP-1 and NF-kappaB control important cell processes like proliferation, apoptosis and differentiation. Disturbance of this processes is often a reason of carcinogenesis. Therefore AP-1 and NF-kappaB might have an important role in arising and development of tumors.

THE AIM OF THE STUDY

An evaluation of changes of AP-1 and NF-kappaB protein level in selected human alimentary tract tumors. Material and methods. Materials were obtained from patients with alimentary tract tumors (stomach, liver; colon), diagnosed by routine histopathological examination. Normal tissues were taken more than 6-7 cm away from tumor border (histologically examined). Protein level of AP-1 and NF-kappaB was detected by standard Western blotting technique.

RESULTS

In all examined alimentary tract tumors (gastric adenocarcinoma, hepatocellular carcinoma, colorectal adenocarcinoma and liver metastases) we observed changes in AP-1 and NF-kappaB protein level comparing with normal tissues.

CONCLUSIONS

Changes in AP-1 and NF-kappaB expression indicate, that they are important factors not only in initiation, but also in further development of digestive tract tumors.

[Folic acid in physiology and pathology]

This paper presents current knowledge of the biological functions of folic acid, the effects of its deficiency in the organism, as well as the possibilities of its therapeutic use. Folic acid (folate, B9) is a vitamin of special importance in normal cellular functions. Tetrahydrofolate (TH4-folate) is the biologically active form of folic acid. The main role of folic acid in biochemistry is the single-carbon transfer reaction (e.g. transfer of a methyl, methylene, or formyl group). Folic acid is involved in the transformation of certain amino acids as well as in the synthesis of purines and dTMP (2'-deoxythymidine-5'-phosphate) needed for the synthesis of nucleic acid (DNA), required by all rapidly growing cells. In humans, folate deficiency results in serious pathologies, the most important of which are neural tube defects, megablastic anemia, acceleration of the arteriosclerotic process, changes in the central nervous system, and the development of certain types of cancer. To increase the intake of folic acid, preventive actions include dietary education, the main objectives of which are to increase the intake of natural folate in the daily diet, add folic acid to selected dietary products (e.g. fl our, pasta, rice), and encourage supplementation with folic acid-containing pharmaceuticals.

Glutathione level and glutathione-dependent enzyme activities in blood serum of patients with gastrointestinal tract tumors

OBJECTIVES

Glutathione (GSH) and enzymes cooperating with it - glutathione peroxidase (GSHPx), glutathione S-transferase (GST) and glutathione reductase (GSHR) - play crucial role in cell defence against reactive oxygen species (ROS), which are implicated in tumor disease. The aim of this study was to determine if neoplastic diseases of gastrointestinal tract may influence blood GSH level and its dependent enzyme activity.

DESIGN AND METHODS

Blood serum was obtained before and after surgery from patients with gastric, liver and colorectal cancers, and colorectal cancer liver metastases. Lipid peroxidation and GSH levels, and GSH-dependent enzyme activities were determined by means of spectrophotometric methods.

RESULTS

Increased level of lipid peroxidation and significant differences in GSH level and GSHPx, GST and GSHR activities were observed in serum taken before and after surgery from patients with gastrointestinal tract tumors compared to those in control serum (from healthy blood donors).

CONCLUSIONS

Increase of lipid peroxidation and changes in GSH level and related enzyme activities, suggest oxidative stress in serum of patients with gastrointestinal tract tumor causes, which probably arise as a result of enormous production of ROS in the system. These alterations reflect the presence of functional defence mechanism against oxidative stress related firmly to the glutathione metabolism.

Changes in antioxidant defense systems induced by thiram in V79 Chinese hamster fibroblasts

The role of antioxidant defence systems in protection against oxidative damage of lipids and proteins induced by fungicide thiram during in vitro exposure was investigated in cultured Chinese hamster V79 cells with normal, depleted, and elevated glutathione (GSH) levels. We analyzed the catalytic activities of superoxide dismutases (SOD1 and SOD2), Se-dependent and Se-independent glutathione peroxidases (GSH-Px), glutathione reductase (GR), and catalase (CAT), as well as total glutathione/glutathione disulfide ratio (GSH(total)/GSSG). Thiram treatment resulted in an increase in activities of SOD1, Se-dependent GSH-Px, and GR at the highest tested dose (150 microM). On the contrary, inhibition of CAT and Se-independent GSH-Px activities, and no significant changes in the level of SOD2 activity was observed at any tested doses (100-150 microM). GSH(total)/GSSG ratio in the 100 microM thiram treated cells was not significantly changed comparing to the control, despite significant decrease of GSH total (50%). In 150 microM thiram treated cells the ratio falls to 43% of control value. Pretreatment with l-buthionine sulfoximine (L-BSO), an inhibitor of GSH synthesis, significantly enhanced decrease in CAT and Se-independent GSH-Px activities, as well as GSH(total)/GSSG ratio, and reduced Se-dependent GSH-Px activity, following exposure to thiram. Simultaneously, L-BSO pretreatment enhanced increase in SOD1 activity, and had no effect on SOD2, following thiram exposure. Pretreatment with N-acetyl cysteine (NAC), a GSH precursor, prevented enzymatic changes in CAT, Se-dependent GSH-Px, GR, SOD1 activities, and significantly decreased SOD2 activity following exposure to thiram. GSH(total)/GSSG ratio was restored to the control value. This study suggests that following the changes in antioxidant defense systems thiram can act through the production of free radicals.

Glutathione and GSH-dependent enzymes in patients with liver cirrhosis and hepatocellular carcinoma

We investigated glutathione level, activities of selenium independent GSH peroxidase, selenium dependent GSH peroxidase, GSH S-transferase, GSH reductase and the rate of lipid peroxidation expressed as the level of malondialdehyde in liver tissues obtained from patients diagnosed with cirrhosis or hepatocellular carcinoma. GSH level was found to be lower in malignant tissues compared to adjacent normal tissues and it was higher in cancer than in cirrhotic tissue. Non-Se-GSH-Px activity was lower in cancer tissue compared with adjacent normal liver or cirrhotic tissue, while Se-GSH-Px activity in cancer was found to be similar to its activity in cirrhotic tissue and lower compared to control tissue. An increase in GST activity was observed in cirrhotic tissue compared with cancer tissue, whereas the GST activity in cancer was lower than in adjacent normal tissue. The activity of GSH-R was similar in cirrhotic and cancer tissues, but higher in cancer tissue compared to control liver tissue. An increased level of MDA was found in cancer tissue in comparison with control tissue, besides its level was higher in cancer tissue than in cirrhotic tissue. Our results show that the antioxidant system of cirrhosis and hepatocellular carcinoma is severely impaired. This is associated with changes of glutathione level and activities of GSH-dependent enzymes in liver tissue. GSH and enzymes cooperating with it are important factors in the process of liver diseases development.

[Activity of antioxidant enzymes in patients with liver cirrhosis]

The aim of our studies was the estimation of activities of antioxidant enzymes in patients with liver cirrhosis. We investigated activities of superoxide dismutases (CuZnSOD, MnSOD), catalase (CAT), selenium dependent GSH peroxidase (Se-GSH-Px), selenium independent GSH peroxidase (non-Se-GSH-Px), GSH-S-transferase (GST), GSH reductase (GSHR) and the level ofreduced gutathione (GSH) in cirrhotic and healthy liver tissues. The activities of CuZnSOD, MnSOD, CAT and GSH-dependent enzymes (except GSHR) were found to be lower in cirrhotic tissue compared to healthy liver. Those changes were associated with decrease of GSH level in cirrhotic tissue compared with control liver tissue. Our results show that antioxidant barrier in liver cirrhosis is impaired. It is associated with decrease of glutathione level and changes of activities of antioxidant enzymes (SOD, CAT, GSHPx, GST, GSHR) in liver cirrhosis compared with healthy liver.

[Catalase: structure, properties, functions]

Catalase (EC 1.11.1.6) is an enzyme which is present mainly in the peroxisomes of mammalian cells. It is a tetrameric enzyme consisting of four identical, tetrahedrally arranged subunits of 60 kDa, each containing in its active center a heme group and NADPH. Catalase has two enzymatic activities depending on the concentration of H2O2. If the concentration of H2O2 is high, catalase acts catalytically, i.e. removes H2O2 by forming H2O and O2 (catalatic reaction). However, at a low concentration of H2O2 and in the presence of a suitable hydrogen donor, e.g. ethanol, methanol, phenol, and others, catalase acts peroxidically, removing H2O2, but oxidizing its substrate (peroxidatic reaction). The review article presents current knowledge about the structure, properties, and functions of catalase in living organisms.

Glutathione and GSH-dependent enzymes in patients with liver cirrhosis and hepatocellular carcinoma

We investigated glutathione level, activities of selenium independent GSH peroxidase, selenium dependent GSH peroxidase, GSH S-transferase, GSH reductase and the rate of lipid peroxidation expressed as the level of malondialdehyde in liver tissues obtained from patients diagnosed with cirrhosis or hepatocellular carcinoma. GSH level was found to be lower in malignant tissues compared to adjacent normal tissues and it was higher in cancer than in cirrhotic tissue. Non-Se-GSH-Px activity was lower in cancer tissue compared with adjacent normal liver or cirrhotic tissue, while Se-GSH-Px activity in cancer was found to be similar to its activity in cirrhotic tissue and lower compared to control tissue. An increase in GST activity was observed in cirrhotic tissue compared with cancer tissue, whereas the GST activity in cancer was lower than in adjacent normal tissue. The activity of GSH-R was similar in cirrhotic and cancer tissues, but higher in cancer tissue compared to control liver tissue. An increased level of MDA was found in cancer tissue in comparison with control tissue, besides its level was higher in cancer tissue than in cirrhotic tissue. Our results show that the antioxidant system of cirrhosis and hepatocellular carcinoma is severely impaired. This is associated with changes of glutathione level and activities of GSH-dependent enzymes in liver tissue. GSH and enzymes cooperating with it are important factors in the process of liver diseases development.

[Antioxidant barrier in patients with gastric cancer--preliminary study]

Gastric carcinoma is one of the most common malignancies of causes of cancer death world-wide, although its incidence and mortality and decreasing, particularly in developed countries. One of the many factors in its etiopathogenesis are free oxygen radicals and their derivatives, excess of which comes from disturbances of enzymatic and nonenzymatic mechanisms of antioxidant barrier. The aim of this study was the evaluation activities of antioxidant enzymes: superoxide dismutase (CuZnSOD, MnSOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione transferase (GST), glutathione reductase (GSH-R) as well as measurement of glutathione (GSH) and malondialdehyde (MDA) levels both in tissues (cancer and healthy) and in blood serum obtained from patients with gastric cancer.

RESULTS

MnSOD and glutathione dependent enzymes (GSH-Px, GST, GSH-R) activities in gastric cancer were found to be higher than those in healthy stomach tissues. In pre- and postoperative blood serum from patients with gastric cancer was observed increase of CAT and GST as well as decrease of CuZnSOD and GSH-Px compared with the blood serum from healthy blood donors (control group). In preoperative blood serum from patients with gastric cancer GSH-R activity was lower than in control serum, whereas in postoperative serum it was higher compared with serum of the control group. Reduced GSH level was found to be lower in gastric cancer than this in healthy stomach tissue, adjacent to the cancer. Its level was also lower in pre- and postoperative blood serum of patients with gastric cancer compared with level in control serum. MDA concentration was found to be much higher in gastric cancer than this in healthy stomach tissue, whereas weren't significant differences between level of MDA in pre- and postoperative blood serum.

CONCLUSION

Our results showed that functioning of antioxidant barrier of organism is severely impaired in patients with gastric cancer.

[Role of L-carnitine in metabolism, nutrition and therapy]

The review article presents the biosynthesis, metabolism, sources, levels, and general functions of L-carnitine, a naturally occurring compound widely distributed in the body. It is synthesized in the liver, kidney, and brain and carriers long-chain fatty acids into the mitochondria for beta-oxidation and energy production. L-carnitine plays an important role in the translocation of acetyl moieties from the mitochondria to the cytoplasm for acetylcholine synthesis in neurones. Other roles--include removal of excess acyl groups, peroxisomal fatty-acid oxidation, and antioxidant activity.

[Antioxidant status of patients with primary colorectal cancer and liver metastases of colorectal cancer]

In the present work we examined selected parameters of antioxidant status in patients with primary colorectal cancer and liver metastasis of colorectal cancer. Total antioxidant status (TAS), activity of superoxide dismutase (SOD) and catalase (CAT) were examined in colorectal primary cancer, liver metastasis of colorectal cancer and in blood serum of patients before and after surgery. It was found that patients have disordered function of the the antioxidant system. This is demonstrated by decreased TAS and changes in the activity of SOD and CAT, both in tumor tissue and blood serum.

[Usefulness of postoperative assay of arginase activity in blood serum of women after breast cancer resection]

The usefulness of arginase test was evaluated in follow-up of patients after breast cancer resection. The arginase activity was measured in blood serum of 970 patients from January 1996 to December 2000. The arginase activity above the normal value was detected in serum of 539 (55.6%) women. Only 197 (20%) patients demonstrated metastases and recurrence (true positive), 342 (35%) patients were disease free. The normal value of arginase activity was found in blood serum of 431 (44.4%) patients, 360 (36%) of them showed complete remission, whereas 71 (8%) demonstrated recurrence or metastases (false negative). Sensitivity of arginase test in post-surgery diagnostics of breast cancer was 73%. Measuring of arginase activity in blood serum of patients after breast cancer resection may be useful as an additional test confirming the disease dissemination.

[Extracellular superoxide dismutase (EC-SOD)--structure, properties and functions]

EC-SOD catalyzes the dismutation of superoxide radical to hydrogen peroxide and oxygen in the interstitial spaces of tissues and in extracellular fluids (plasma, lymph, and synovial fluid). It eliminates superoxide radicals from the cell environment and prevents the formation of reactive oxygen species and their derivatives. EC-SOD is a secretory, tetrameric glycoprotein containing copper and zinc, with a high affinity to certain glycosaminoglycans, such as heparin and heparan sulfate. It plays an important role in maintaining vascular tone, lung function, and the metabolism of NO, and in the pathology of such diseases as atherosclerosis, diabetes, and arthritis. This paper describes EC-SOD structure, function in tissues, and possibilities of therapy with application of this enzyme.

[Arginine--metabolism and functions in the human organism]

L-arginine plays important roles in the metabolism of an organism. It is the precursor for the synthesis of proteins and other molecules of great biological importance, including nitric oxide, ornithine, polyamines, agmatine, proline, glutamate, creatine, dimethylarginine, and urea. For young organisms arginine is an essential amino acid for optimal growth and development, and must therefore be provided in the diet. For adults, arginine is a conditionally essential amino acid, especially in such conditions as trauma, burn injury, small-bowel resection, and renal failure. L-arginine administration improves cardiovascular, pulmonary, immune, and digestive functions and protect against the early stages of cancerogenesis.

Evaluation of the mutagenic activity of phenolics from the bark of Yucca schidigera Roezl

The mutagenic activity of yuccaols A, B, and C, trans-resveratrol and trans - 3.3',5.5'-tetrahydroxy -4'-methoxystilbene was tested by the Ames method with Salmonella typhimurium strains TA97, TA98, TA100, TA102 in the absence and presence of metabolic activation (S9 fraction). These phenolic compounds have been isolated and identified from the hark of Yucca schidigera. All of them were found to be non-toxic and non-mutagenic for testing doses in any of the S. typhimurium strains.

[Evaluation of antioxidant status in patients with primary hepatocellular carcinoma]

The aim of this work was to evaluate the efficiency of the antioxidant system in patients with primary hepatocellular carcinoma. Total antioxidant status (TAS), superdoxide dismutase (SOD) and catalase (CAT) activity was examined in liver primary cancers and in blood serum of patients before and after surgery. In comparison with healthy liver, very low activity of TAS was observed in liver cirrhosis and in primary cancer. High activity of TAS in the blood serum of patients before and after surgery was comparable with TAS activity in blood serum of healthy persons. The highest activity of SOD and CAT was observed in liver cirrhosis. The lowest activity was observed in liver primary cancer. Activity of SOD and CAT in the blood serum of patients before surgery was higher than in the blood serum of patients after surgery. The highest activity was observed in the blood serum of healthy persons. Obtained results shows, that the dysfunction of the defensive antioxidant mechanisms have characterised with not only local disturbances (in the tumour cells region), but also circuital ones (blood). Low levels of the activity of TAS, SOD and CAT in patients with primary hepatocellular carcinoma indicate to the distortion of the oxidant--antioxidant balance and the decrease of organism antioxidant system efficiency. These observations show at the participation of free radical processes in the tumour pathogenesis.

Antitumor effects of photodynamic therapy are potentiated by 2-methoxyestradiol. A superoxide dismutase inhibitor

Photodynamic therapy (PDT), a promising therapeutic modality for the management of solid tumors, is a two-phase treatment consisting of a photosensitizer and visible light. Increasing evidence indicates that tumor cells in regions exposed to sublethal doses of PDT can respond by rescue responses that lead to insufficient cell death. We decided to examine the role of superoxide dismutases (SODs) in the effectiveness of PDT and to investigate whether 2-methoxyestradiol (2-MeOE(2)), an inhibitor of SODs, is capable of potentiating the antitumor effects of this treatment regimen. In the initial experiment we observed that PDT induced the expression of MnSOD but not Cu,Zn-SOD in cancer cells. Pretreatment of cancer cells with a cell-permeable SOD mimetic, Mn(II)-tetrakis(4-benzoic acid)porphyrin chloride, and transient transfection with the MnSOD gene resulted in a decreased effectiveness of PDT. Inhibition of SOD activity in tumor cells by preincubation with 2-MeOE(2) produced synergistic antitumor effects when combined with PDT in 3 murine and 5 human tumor cell lines. The combination treatment was also effective in vivo producing retardation of the tumor growth and prolongation of the survival of tumor-bearing mice. We conclude that inhibition of MnSOD activity by 2-MeOE(2) is an effective treatment modality capable of potentiating the antitumor effectiveness of PDT.

Induction of rat liver cytochrome P450 isoenzymes CYP 1A and CYP 2B by different fungicides, nitrofurans, and quercetin

The genotoxic activity of environmental xenobiotics is manifested either in their direct interaction with cellular genetic material or in provoking secondary events, among which reactive oxygen species (ROS) production is a common phenomenon. Both pathways can be mediated by the activity of the cytochrome P450 monooxygenase system. We studied induction of the CYP 1A or CYP 2B monooxygenases in rat liver by the fungicides: thiram, captan, captafol, dodine and the drugs: nitrofurazone, furazolidone and the plant flavonoid: quercetin. A cytochrome P450 induction assay (CYPIA test) was used. S9 prepared from livers of rats treated with the test compounds were used to activate ethidium bromide (EtBr) (CYP 1A isoenzyme) or cyclophosphamide (CPA) (CYP 2B isoenzyme) in the Ames test. It was found that among the tested compounds, the most potent inducer of CYP 1A was furazolidone (3 x 80 mg/kg). Less potent was thiram (1 x 100mg/kg), as well as quercetin (3 x 80 mg/kg), and captafol (1 x 30 mg/kg). On the other hand, thiram (1 x 100 mg/kg), captafol (1 x 30 mg/kg), and quercetin (3 x 80 mg/kg) were most potent in the CYP 2B isoenzyme induction, while furazolidone (3 x 80 mg/kg), and nitrofurazone (3 x 80 mg/kg) appeared to be less potent in this respect. Captan and dodine (3 x 80 mg/kg) did not affect the activity of any of the cytochrome P450 isoenzymes.

[Selected short-term bacterial and eukaryotic tests used for detection of genotoxicity of environmental chemical contaminants]

During the last years human exposure to environmental chemical contaminants (mutagenic/carcinogenic agents) has greatly increased. Evaluation of the biological effect of human exposure to mutagenic/carcinogenic agents in short-term tests is very important. In present paper the bacterial and eukaryotic tests for detection of genotoxic effect of environmental chemical contaminants have been described.