PurposeTherapeutic selectivity is one of the most important considerations in cancer chemotherapy. The design of therapeutic strategies to preferentially kill malignant cells while minimizing harmful effects to normal cells depends on our understanding of the biological differences between cancer and normal cells. We have previously demonstrated that certain agents generating reactive oxygen species (ROS) such as 2-methoxyestradiol (2-ME) preferentially kill human leukemia cells without exhibiting significant cytotoxicity in normal lymphocytes. The purpose of the current study was to investigate the biochemical basis for such selective anticancer activity.MethodsFlow cytometric analyses were utilized to measure intracellular O2− levels and apoptosis. MTT assays were used as indicators of cellular viability. Western blot analysis was used to measure the expression of antioxidant enzymes in cancer and normal cells.ResultsMalignant cells in general are more active than normal cells in the production of O2−, are under intrinsic oxidative stress, and thus are more vulnerable to damage by ROS-generating agents. The intrinsic oxidative stress in cancer cells was associated with the upregulation of SOD and catalase protein expression, likely as a mechanism to tolerate increased ROS stress. The increase in SOD and catalase expression was observed both in primary human leukemia cells and in primary ovarian cancer cells. Both malignant cell types were more sensitive to 2-ME than their normal counterparts, as demonstrated by the significant accumulation of O2− and subsequent apoptosis. The administration of ROS scavengers in combination with 2-ME prevented the accumulation of O2− and abrogated apoptosis induction.ConclusionsO2− is an important mediator of 2-ME-induced apoptosis. The increased oxidative stress in cancer cells forces these cells to rely more on antioxidant enzymes such as SOD for O2− elimination, thus making the malignant cells more vulnerable to SOD inhibition than normal cells.

Intrinsic oxidative stress in cancer cells: A biochemical basis for therapeutic selectivity using ROS -generating agents

Choerospondias axillaris (Guangzao) is a medicinal plant used in Mongolia, and its fruit is commonly used for the treatment of cardiovascular diseases in clinic. The constituents responsible for this effect are always conceded to be the total flavonoids of C. axillaries (TFC). The present study was to evaluate the preventive effect of TFC on acute myocardial infarction induced by ischemia/reperfusion (I/R) in rats and the possible signaling pathway involved. The model of myocardial I/R was caused by occlusion of the left anterior descending coronary artery for 30 min followed by reperfusion for 2 h. Cardiac dysfunction, infarct size, pathologic histology and apoptosis were examined. Heart tissues were homogenized for biochemistry assays and Western blots analysis. The results indicated that pretreatment with TFC strongly improved cardiac function, obviously reduced heart pathologic lesion in I/R rat hearts. TFC also could protect the heart from I/R injury by increasing the levels of catalase, glutathione peroxidase and superoxide dismutase in heart homogenate, and decreasing that of malondialdehyde level. These beneficial effects were associated with the decrease in TUNEL-positive nuclear staining, Bax and caspase-3 levels, and the increase in Bcl-2 expression. Moreover, TFC counteracted the I/R-induced decreased activation of p38 mitogen-activated protein kinase (MAPK) and Jun N-terminal kinase. These data suggested that TFC improved I/R-induced myocardium impairment via anti-oxidative and anti-apoptotic activities, and this beneficial effects were intervened by MAPK signaling pathway.

Preventive Effect of Total Flavones of Choerospondias axillaries on Ischemia/Reperfusion-Induced Myocardial Infarction-Related MAPK Signaling Pathway

Excited States and Free Radicals in Biology and Medicine: contributions from flash photolysis and pulse radiolysis

http://www.tara.tcd.ie/bitstream/handle/2262/67565/MS246-Tara.pdf%3bsequence=1

Platelets, photosensitizers, and PDT.

The outcome of molecular targeted therapies is restricted by the ambiguous molecular subtypes of nonsmall cell lung cancer (NSCLC), which are difficult to be defined with druggable mutations, and the inevitable emergence of drug-resistance. Here we used the Cu-catalyzed click chemistry to synthesize a chitosan-based self-assembled nanotheranostics (CE7Ns) composed of a near-infrared (NIR) fluorescent photosensitizer Cy7 and molecular targeted drug erlotinib. The well-characterized CE7Ns can release erlotinib and Cy7 fast under acidic condition in the presence of lysozyme, distinguish three molecular subtypes of NSCLC, and specifically bind to the erlotinib-sensitive epidermal growth factor receptor (EGFR)-mutated PC-9 cells. The uptake of CE7Ns is much more in PC-9 cells than in other NSCLC cells, thus generating a notable fluorescence signal in PC-9 cells. Upon NIR irradiation, Cy7 in CE7Ns produces high reactive oxygen species in PC-9 cells. The synergistic effect between erlotinib-targeted therapy and ...

Erlotinib-Guided Self-Assembled Trifunctional Click Nanotheranostics for Distinguishing Druggable Mutations and Synergistic Therapy of Nonsmall Cell Lung Cancer

Septic shock is a systemic inflammation associated with cell metabolism disorders and cardiovascular dysfunction. Increases in O-GlcNAcylation have shown beneficial cardiovascular effects in acute pathologies. We used two different rat models to evaluate the beneficial effects of O-GlcNAc stimulation at the early phase of septic shock. Rats received lipopolysaccharide (LPS) to induce endotoxemic shock or saline (control) and fluid resuscitation (R) with or without O-GlcNAc stimulation (NButGT–10 mg/kg) 1 hour after shock induction. For the second model, rats received cecal ligature and puncture (CLP) surgery and fluid therapy with or without NButGT. Cardiovascular function was evaluated and heart and blood samples were collected and analysed. NButGT treatment efficiently increased total O-GlcNAc without modification of HBP enzyme expression.Treatment improved circulating parameters and cardiovascular function in both models, and restored SERCA2a expression levels. NButGT treatment also reduced animal mortality. In this study, we demonstrate that in septic shock O-GlcNAc stimulation improves global animal and cardiovascular function outcomes associated with a restoration of SERCA2a levels. This pre-clinical study opens avenues for a potential therapy of early-stage septic shock.

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O-GlcNAc stimulation: A new metabolic approach to treat septic shock.

Singlet oxygen (1O2) is produced by leucocytes during inflammatory reactions, various biochemical reactions and during photoreactions It deactivates by reacting with a number of targets to produce reactive oxygen species (ROS) and peroxides (that in turn produce ROS) To verify whether serum had the same capability to deactivate secondary oxidants after exposure to 1O2, we provoked a photoreaction using rose bengal added to sera of 53 healthy donors and, after light delivery, reduced 2′,7′-dichlorofluorescein (DCFH) was added at the end of irradiation and fluorescence of the oxidized derivative (DCF) was recorded To avoid optical artifacts, we analyzed the influence of hemolysis Deactivation capability of secondary oxidants after exposure to 1O2 was stable over a long period of time, slightly different between men and women, but standard biochemistry parameters had little influence Hemolysis, age and platelet number reduced deactivation of 1O2-induced secondary oxidants Addition of lysed cancer cells had no influence Blood sampling in clot act tubes gave a better signal than in heparinized tubes Red blood cells (RBCs) loaded with antioxidants strongly decreased deactivation of secondary oxidants Assays are in progress to evaluate the clinical implications of these findings

https://link.springer.com/content/pdf/10.1039/b9pp00032a.pdf

Secondary oxidants in human serum exposed to singlet oxygen: the influence of hemolysis

Secondary reactive oxygen species production after PDT during pulmonary tumor growth in sera of nude mice.

Photodynamic therapy (PDT) generates singlet oxygen (1O2) and Reactive Oxygen Species (ROS) that are counteracted by patient’s defenses. As cancer treatments are among the most important PDT applications the aim of this pilot study was to determine whether the serum of cancer patients produces more or less secondary ROS or peroxides after a photoreaction as compared to healthy persons. Fifty-three volunteers and 105 cancer patients were recruited. The capacity of 1O2 or secondary oxidant production was found to be increased in 6 healthy donors and 36 cancer patients (23/69 women and 13/31 men p

Increased singlet oxygen-induced secondary ROS production in the serum of cancer patients.

Blood flow arrest and reperfusion during myocardial infarction (MI) cause myocyte and endothelium injury through oxidative stress and inflammation, both of which involve Reactive Oxygen Species (ROS) and peroxides that consume antioxidant defenses. The aim of this study was to determine whether serum from the occluded coronary vessel has impaired anti-oxidative defenses as compared to serum from aortic blood or from the periphery of healthy controls. Forty-seven patients (44 men) were included for study. Inclusion criteria were chest pain, ST elevation, and cardiac troponin increase. A photoreaction producing a standardized amount of singlet oxygen (1O2), an excited form of oxygen, was performed in serum samples obtained during primary percutaneous coronary intervention (PCI). Immediately after laser light delivery to 5 % sera containing 5 µg/mL rose bengal, dichloro-dihydro-fluorescein (DCFH) was added and its post-oxidation transformation into the fluorescent DCF, was recorded. At least 5 h after the start of symptoms, the mean secondary ROS production after 1O2 delivery was increased in coronary sera (p < 0.001), but in aortic blood remained similar to that of healthy controls. The peak troponin value correlated with DCF fluorescence throughout the interval between symptoms onset and PCI. A high fluorescence was associated with a higher risk of MACE. These results show that oxidants secondary to 1O2 are increased in occluded vessels during AMI in parallel to c-troponin, demonstrating that antioxidants are consumed. A O2 increase during reperfusion would thus extend the damage resulting from IDM necrosis. The effect of conditioning during PCI could be studied using the described method.

Edith Bigot

Papers

O-GlcNAc stimulation: A new metabolic approach to treat septic shock.

Secondary oxidants in human serum exposed to singlet oxygen: the influence of hemolysis

Secondary reactive oxygen species production after PDT during pulmonary tumor growth in sera of nude mice.

Increased singlet oxygen-induced secondary ROS production in the serum of cancer patients.

Evidence for antioxidants consumption in the coronary blood of patients with an acute myocardial infarction