DNA damage of tumor-associated lymphocytes and total antioxidant capacity in cancerous patients

Oxidatively Damaged Nucleic Acid: Linking Diabetes and Cancer

Significance: Our current knowledge of the mechanism between diabetes and cancer is limited. Oxidatively damaged nucleic acid is considered a critical factor to explore the connections between these two diseases. Recent Advances: The link between diabetes mellitus and cancer has attracted increasing attention in recent years. Emerging evidence supports that oxidatively damaged nucleic acid caused by an imbalance between reactive oxygen species generation and elimination is a bridge connecting diabetes and cancer. 8-Oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydroguanosine assume important roles as biomarkers in assessing the relationship between oxidatively damaged nucleic acid and cancer. Critical Issues: The consequences of diabetes are extensive and may lead to the occurrence of cancer by influencing a combination of factors. At present, there is no direct evidence that diabetes causes cancer by affecting a single factor. Furthermore, the difficulty in controlling variables and differences in detection methods lead to poor reliability and repeatability of results, and there are no clear cutoff values for biomarkers to indicate cancer risk. Future Directions: A better understanding of connections as well as mechanisms between diabetes and cancer is still needed. Both diabetes and cancer are currently intractable diseases. Further exploration of the specific mechanism of oxidatively damaged nucleic acid in the connection between diabetes and cancer is urgently needed. In the future, it is necessary to further take oxidatively damaged nucleic acid as an entry point to provide new ideas for the diagnosis and treatment of diabetes and cancer. Experimental drugs targeting the repair process of oxidatively generated damage require an extensive preclinical evaluation and could ultimately provide new treatment strategies for these diseases. Antioxid. Redox Signal. 37, 1153-1167.

Effects of PM2.5 on Chronic Airway Diseases: A Review of Research Progress

The adverse effects of polluted air on human health have been increasingly appreciated worldwide. It is estimated that outdoor air pollution is associated with the death of 4.2 million people globally each year. Accumulating epidemiological studies indicate that exposure to ambient fine particulate matter (PM2.5), one of the important air pollutants, significantly contributes to respiratory mortality and morbidity. PM2.5 causes lung damage mainly by inducing inflammatory response and oxidative stress. In this paper, we reviewed the research results of our group on the effects of PM2.5 on chronic obstructive pulmonary disease, asthma, and lung cancer. And recent research progress on epidemiological studies and potential mechanisms were also discussed. Reducing air pollution, although remaining a major challenge, is the best and most effective way to prevent the onset and progression of respiratory diseases.

Immunoregulatory role of melatonin in cancer

Melatonin is a ubiquitous indole amine that plays a fundamental role in the regulation of the biological rhythm. Disrupted circadian rhythm alters the expression of clock genes and deregulates oncogenes, which finally promote tumor development and progression. An evidence supporting this notion is the higher risk of developing malignancies among night shift workers. Circadian secretion of the pineal hormone also synchronizes the immune system via a reciprocal association that exists between the immune system and melatonin. Immune cells are capable of melatonin biosynthesis in addition to the expression of its receptors. Melatonin induces big changes in different immune cell proportions, enhances their viability and improves immune cell metabolism in the tumor microenvironment. These effects might be directly mediated by melatonin receptors or indirectly through alterations in hormonal and cytokine release. Moreover, melatonin induces apoptosis in tumor cells via the intrinsic and extrinsic pathways of apoptosis, while it protectsthe immune cells. In general, melatonin has a profound impact on immune cell trafficking, cytokine production and apoptosis induction in malignant cells. On such a basis, using melatonin and resynchronization of sleep cycle may have potential implications in immune function enhancement against malignancies, which will be the focus of the present paper.

The Protective Effect of Melatonin against Fumonisin-Induced Renal Damage in Rats

The present study was designed to investigate the potential protective effect of melatonin against the renal toxicity of fumonisin in female rats. Six groups of animals were used in this study. The first group served as control. The second group was given melatonin only at a dose level of 10 mg/kg. The third group was fed ration contaminated with fumonisin (100 mg/kg diet). The fourth group was fed ration contaminated with fumonisin (200 mg/kg diet). The fifth group was given daily interperitoneal injection (IP) 10 mg/kg melatonin and fed ration contaminated with fumonisin (100 mg/kg diet). The sixth group was given daily interperitoneal injection of 10 mg/kg melatonin and fed ration contaminated with fumonisin (200 mg/kg diet). The rats were treated for 1 month. Histopathological and histochemical changes in the kidney were investigated. In addition, DNA ploidy was measured in the kidney. Fumonisin administration (100 or 200 mg/Kg diet) to unpretreated control rats caused extensive renal damage as evaluated by histopathology, histochemistry, and/or DNA ploidy measurement. No apparent changes following administration of melatonin. Melatonin coadministration to the fumonisin-administered rats reduced kidney damage and the tissues appeared more or less like the normal. The present study indicates that melatonin has a protective effect in fumonisin-induced renal damage.

Interactions between oxidative stress, lipid profile and antioxidants in breast cancer: a case control study

Oxidant/antioxidant balance has been suggested as an important factor for initiation and progression of cancer. The objective of this study was to determine changes in the levels of malondialdehyde (MDA), nitric oxide (NO), total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol, total antioxidant capacity (TAC), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) activities in serum samples of breast cancer patients (n=30) and healthy subjects (n=100). MDA and NO levels were found to be increased in breast cancer patients compared to the healthy subject group (p<0.05). Total cholesterol and triglycerides were elevated; and HDL- cholesterol level was found to be decreased in the cancer patients as compared to the healthy subjects (p<0.05). Compared to the healthy group, both serum TAC levels (p<0.001) and activity of SOD and GSH-Px (p=0.05) were found to be decreased in the breast cancer patients as compared to the healthy controls. Considering the data presented in this study, we suggest that free radicals induce lipid eroxidation and peroxidation of unsaturated fatty acid with decreased activity of enzymatic antioxidants in breast cancer.

Dynamic oxidative stress and DNA damage induced by oestrogen deficiency and protective effects of puerarin and 17β-oestradiol in ovariectomized rats

Oxidative stress plays an essential role in the pathogenesis of cardiovascular diseases and osteoporosis resulting from oestrogen deficiency in the postmenopausal period. In this report, we observed a dynamic change of oxidative stress and DNA damage after ovariectomy in female rats. We then compared phytoestrogen puerarin and 17β-oestradiol (E₂) in their effects on oestrogen deficiency-induced oxidative stress and DNA damage. Serum total antioxidant capacity (TAC), malondialdehyde (MDA) and lymphocytes DNA damage (comet%) were measured. There was a gradual increase in oxidative stress in the ovariectomized (OVX) rats over time after ovariectomy, as compared to rats receiving sham operation. OVX rats that were on puerarin and E₂ showed increased TAC and decreased MDA in the serum, as well as decreased lymphocytes comet%. Puerarin appeared to have a more powerful protective effect on DNA oxidative damage than E₂. The study indicates that postmenopausal women may benefit from phytoestrogen puerarin.

Egyptian sweet marjoram leaves protect against genotoxicity, immunosuppression and other complications induced by cyclophosphamide in albino rats

Cyclophosphamide (CP) is one of the most popular alkylating anticancer drugs that show a high therapeutic index, despite the widespread side effects and toxicity particularly in high-dose regimens and long-term use. Here, we evaluated and compared the efficacy of two different doses (50 and 100 mg/kg body weight, given orally for 30 consecutive days) of Egyptian sweet marjoram leaf powder (MLP) and marjoram leaf aqueous extract (MLE) in alleviating the genotoxicity, immunosuppression and other complications induced by CP in non-tumour-bearing albino rats. The present study showed (probably for the first time) that both MLP and MLE significantly alleviated (P < 0·05–0·001) most side effects and toxicity of CP-treated rats including the increase in chromosomal aberrations of bone marrow cells and serum malondialdehyde level, the decrease in the level of serum Ig, the delayed type of hypersensitivity response as also the weights and cellularity of lymphoid organs, and myelosuppression, leucopenia, macrocytic normochromic anaemia as well as thrombocytopenia by reactivating the non-enzymic (reduced glutathione) and enzymic (catalase, glutathione peroxidase, glutathione S-transferase, superoxide dismutase) antioxidant system and increasing the mitotic index of bone marrow cells. The modulatory effects of marjoram leaves shown in the present study were dose dependent in most cases and much higher in MLE (21–23 % for all parameters taken together). In addition, the doses used in the present study were considered safe. In conclusion, sweet marjoram leaves (especially in the form of a herbal tea) may be useful as an immunostimulant and in reducing genotoxicity in patients under chemotherapeutic interventions.

Study of serum antioxidant capacity and relation with CA 19-9 and PSA in patients with gastrointestinal tract and prostate tumors

OBJECTIVES

We undertook the present study to investigate the possible relation between total antioxidant capacity (TAC) and tumor marker (TM) values in serum samples of patients with and without gastrointestinal tract and prostate tumors.

DESIGN AND METHODS

We measured the TAC using trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorption capacity (ORAC) assays in 80 serum samples: 20 presented elevated values of CA 19-9; 20 had elevated PSA levels and two groups of 20 samples had values within reference ranges respectively.

RESULTS

Total antioxidant capacity - measured using the two different analytical methods - was higher in serum samples from patients with elevated CA 19-9 and PSA levels. This antioxidant status, measured by ORAC assay, correlated significantly with CA 19-9 (r: 0.502, P<0.05) and PSA (r:0.792, P<0.001) when the values of these tumor markers were pathological.

CONCLUSIONS

We concluded that increased serum TAC of the patients with altered levels of CA 19-9 and PSA may be due to the response of increased reactive oxygen species and can be considered as a sign of oxidative stress of these patients. We know that tumor markers are a useful tool for follow-up care of oncologic patients, whereas their role in the diagnosis of a malignancy is controversial. Therefore, the evaluation of serum antioxidant capacity in these pathological processes could contribute to improve diagnosis of these patients.

DNA and cytogenetic damage in white blood cells of postmenopausal breast cancer patients treated with radiotherapy

The primary and residual genome damage and its elimination rate were evaluated in peripheral blood lymphocytes of breast cancer patients treated with adjuvant radiotherapy after surgical removal of the tumor by mastectomy or quadrantectomy. The levels of DNA/chromosome damage were estimated before, throughout, as well as after six months, respectively one year after the radiotherapy, using the alkaline comet assay, the chromosome aberration analysis and the cytokinesis-block micronucleus assay. The marked individual differences in the baseline genome damage were observed in patients, which additionally increased until the end of the radiotherapy cycle. The levels of DNA/cytogenetic damage slowly declined during post-irradiation period; although in the majority of subjects they did not return to pre-therapy levels. In addition to the well-established comet parameters, the long-tailed nuclei were also proved as a useful indicator of individual DNA damage and response to radiation. One of the most important observation was that older breast cancer patients, irradiated after mastectomy, had higher values of almost all parameters evaluated. We found positive correlations between the comet assay parameters and the cytogenetic biomarkers that confirmed their complementary value in the assessment of the radiation sensitivity/susceptibility in elderly breast cancer patients. The specific patterns of DNA damage observed in the majority of subjects after a prolonged exposure to ionizing radiation indicate the possibility of adaptive response. Such results may also be linked to the hormesis theory and support previous observations, but the underlying mechanisms should be further investigated on a much larger population.

Association of low repair efficiency with high hormone receptors expression and SOD activity in breast cancer patients

OBJECTIVES

To evaluate the antioxidant status and repair capacity in breast cancer patients as well as the relationship between these parameters and expression of critical proteins in breast cancer tissue.

DESIGN AND METHODS

Blood samples were obtained from 25 female breast cancer patients and 19 healthy women. The antioxidant status was determined by the concentration of thiobarbituric-reactive substances (TBARS) and activity of superoxide dismutase (SOD) and catalase (CAT). The basal DNA damage and repair capacity in lymphocytes were evaluated by comet assay. The expression of p53, c-erbB2, Ki-67, estrogen receptor (ER) and progesterone receptor (PR) in cancer tissue was detected by immunohistochemical staining.

RESULTS

The breast cancer patients presented significantly elevated endogenous DNA damage in lymphocytes and lower susceptibility to DNA damage induced by H(2)O(2) when compared to the control group. There is a negative correlation between TBARS and sensitivity to peroxide induced DNA damage in patients. The percentage of residual damage after H(2)O(2) treatment followed by 3h of post-incubation is significantly higher in patients and also correlates positively with SOD activity, ER and PR expression and negatively with the basal DNA damage.

CONCLUSIONS

Our results demonstrate low repair capacity in lymphocytes of breast cancer patients and suggest that the regulation of DNA repair is sensitive to cellular redox state and can be modulated by ER/PR status.

Relationship between DNA damage and total antioxidant capacity in patients with transitional meningioma

PURPOSE

The purpose of this study was to assess oxidative DNA damage and total antioxidant capacity (TAC) in patients with transitional meningioma (TM) and to compare the results with normal brain tissues.

PATIENTS AND METHODS

Oxidative DNA damage and TAC were evaluated in TM extracted from 22 patients and in normal brain tissues of 15 subjects who underwent autopsy within first 4h of death. Oxidative DNA damage was assessed by measuring 8-hydroxy-2-deoxyguanosine (8-OH-dG) using the 8-OH-dG enzyme immunoassay kit, a quantitative assay for 8-OH-dG, and TAC was analyzed using the ImAnOx colorimetric test system for the determination of antioxidative capacity. The results were compared between two groups and any correlation between 8-OH-dG and TAC was sought.

RESULTS

The median level of TAC in TM (135nmol/gwet tissue) was remarkably lower than in normal brain tissue (298nmol/gwet tissue). The difference was statistically significant (p=0.00001). In contrast, oxidative DNA damage was significantly higher in patients with TM (71.61ng/gwet tissue) than in controls (34.71ng/gwet tissue). Again, the difference was statistically significant (p=0.00001). We also found a negative correlation between oxidative DNA damage and TAC (p<0.001).

CONCLUSION

These findings show that the degree of oxidative DNA damage is increased and TAC is decreased in TM and oxidative DNA damage is negatively correlated with the levels of TAC.

Redox molecules and cancer prevention: the importance of understanding the role of the antioxidant network

Cancer has a complex etiology with multiple risk factors that involve the interplay between genetic and environmental influences. There is compelling evidence that dietary plant foods appear to be protective against certain type of cancers. Among a number of mechanistic hypotheses, diet-derived antioxidants have been proposed to contribute to explain these findings. However, contrasting results from intervention trials have raised strong concerns about the influence of antioxidants on human health. A vulnerable point of the research on antioxidants is the lack of information on the effect of the whole array of dietary antioxidants in cancer prevention because so far mainly single molecules have been investigated. Total antioxidant capacity (TAC) considers the single antioxidant activity as well as the synergistic interactions of the redox molecules present in complex matrixes, giving an insight into the assessment of the non-enzymatic antioxidant network. This article will outline the state of art of the research on TAC and cancer, describing the plasma non-enzymatic antioxidant network and its association with diet. The feasibility of TAC assessment as an innovative tool for investigating the association between dietary antioxidants, oxidative stress, and cancer will be also discussed.

Relationship Between DNA Damage and Total Antioxidant Capacity in Patients with Glioblastoma Multiforme

AIMS

To assess oxidative DNA damage and total antioxidant capacity (TAC) in glioblastoma multiforme (GBM) and to compare the results with normal brain tissues.

MATERIALS AND METHODS

Oxidative DNA damage and TAC were evaluated in GBM tissues extracted from 26 patients and in normal brain tissues of 15 subjects who underwent autopsy within the first 4h of death. Oxidative DNA damage was assessed by measuring 8-hydroxy-2-deoxyguanosine (8-OH-dG) using the 8-OH-dG enzyme immunoassay kit, a quantitative assay for 8-OH-dG, and TAC was analysed using the ImAnOx colorimetric test system for the determination of antioxidative capacity. The results were compared between two groups and any correlation between 8-OH-dG and TAC was sought.

RESULTS

The median level of TAC in GBM (121.5 nmol/g wet tissue) was remarkably lower than that in normal brain tissue (298 nmol/g wet tissue). The difference was statistically significant (P=0.00001). In contrast, oxidative DNA damage was significantly higher in patients with GBM (74.9 ng/g wet tissue) than in controls (34.71 ng/g wet tissue). Again, the difference was statistically significant (P=0.00001). We also found a negative correlation between oxidative DNA damage and TAC (P<0.001).

CONCLUSIONS

These findings indicate that the degree of oxidative DNA damage is increased and TAC is decreased in GBM. Oxidative DNA damage is correlated with the levels of TAC.

The role of reactive oxygen species in the herbicide acetochlor-induced DNA damage on Bufo raddei tadpole liver

After exposure of Bufo raddei tadpoles to acetochlor (ACETO) for 14 days, malondialdehyde (MDA) and DNA-single strand break (DNA-SSB) in livers were analyzed. An enhanced accumulation of MDA suggests that ACETO causes oxidative stress, and the significant increase in the level of DNA-SSB indicates that ACETO induces DNA damage in a dose-dependent manner as well. On the basis of the fact that oxidative stress is caused by excessive production of reactive oxygen species (ROS), and the present results, we speculate that ACETO-induced DNA damage may be a consequence of the generation of ROS. To evaluate this hypothesis, tadpoles were treated with ROS scavenger, N-acetyl-L-cysteine (NAC) or melatonin (MEL), prior to ACETO exposure. The decrease of DNA-SSB level and the increase of total antioxidant capability (TAC) show that ACETO-caused DNA damage can be attenuated by NAC and MEL. In addition, a negative correlation was observed between the extent of DNA damage and the level of TAC in tadpole liver. In conclusion, the results suggest that ACETO-induced DNA damage is mediated by ROS.

Correlation between formamidopyrimidine DNA glycosylase (Fpg)-sensitive sites determined by a comet assay, increased MDA, and decreased glutathione during long exposure to thinner inhalation

Thinner inhalation causes toxic effects in a variety of organs, principally in the central nervous system. Some studies have shown oxidative stress effects of thinner inhalation, such as: activation of free radical processes, decrease of antioxidants, and oxidation products of proteins and lipids but not of DNA. The aim of this study is to investigate the effect of thinner inhalation on DNA. We used the comet assay in conjunction with the enzyme formamidopyrimidine glycoslyase (Fpg). Our results show a significant increase in Fpg-sensitive sites in DNA of lymphocytes from rats exposed to thinner fumes compared to lymphocytes from control rats (p < 0.05). Moreover, DNA damage detected with Fpg shows a high correlation with increased malondialdehyde (MDA) and decreased glutathione (GSH), two widely used biomarkers of oxidative stress. The most abundant base oxidation product found in DNA is 8-oxoguanine; it is the main substrate of Fpg and the most commonly used biomarker for oxidative DNA damage. This suggests that oxidative DNA damage is at least partly responsible for the DNA damage detected by Fpg. We propose the comet assay in combination with Fpg as a sensitive biomarker to monitor exposure to thinner inhalation. Limitations of this method are discussed.

Overexpression of manganese superoxide dismutase promotes the survival of prostate cancer cells exposed to hyperthermia

It has been hypothesized that exposure of cells to hyperthermia results in an increased flux of reactive oxygen species (ROS), primarily superoxide anion radicals, and that increasing antioxidant enzyme levels will result in protection of cells from the toxicity of these ROS. In this study, the prostate cancer cell line, PC-3, and its manganese superoxide dismutase (MnSOD)-overexpressing clones were subjected to hyperthermia (43 degrees C, 1 h). Increased expression of MnSOD increased the mitochondrial membrane potential (MMP). Hyperthermic exposure of PC-3 cells resulted in increased ROS production, as determined by aconitase inactivation, lipid peroxidation, and H2O2 formation with a reduction in cell survival. In contrast, PC-3 cells overexpressing MnSOD had less ROS production, less lipid peroxidation, and greater cell survival compared to PC-3 Wt cells. Since MnSOD removes superoxide, these results suggest that superoxide free radical or its reaction products are responsible for part of the cytotoxicity associated with hyperthermia and that MnSOD can reduce cellular injury and thereby enhance heat tolerance.