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Modern analytical methods combined with the modern concepts of redox signaling revealed 4- hydroxy-2- nonenal (4-HNE) as particular growth regulating factor involved in redox signaling under physiological and pathophysiological circumstances. In this review current knowledge of the relevance of 4-HNE as "the second messenger of reactive oxygen species" (ROS) in redox signaling of representative major stress- associated diseases is briefly summarized. The findings presented allow for 4-HNE to be considered not only as second messenger of ROS, but also as one of fundamental factors of the stress- and age- associated diseases. While standard, even modern concepts of molecular medicine and respective therapies in majority of these diseases target mostly the disease- specific symptoms. 4-HNE, especially its protein adducts, might appear to be the bioactive markers that would allow better monitoring of specific pathophysiological processes reflecting their complexity. Eventually that could help development of advanced integrative medicine approach for patients and the diseases they suffer from on the personalized basis implementing biomedical remedies that would optimize beneficial effects of ROS and 4-HNE to prevent the onset and progression of the illness, perhaps even providing the real cure.

Regeneration is the process of replacing/restoring a damaged cell/tissue/organ to its full function and is limited respecting complexity of specific organ structures and the level of differentiation of the cells. Unlike physiological cell turnover, this tissue replacement form is activated upon pathological stimuli such as injury and/or disease that usually involves inflammatory response. To which extent will tissue repair itself depends on many factors and involves different mechanisms. Oxidative stress is one of them, either acute, as in case of traumatic brin injury or chronic, as in case of neurodegeneration, oxidative stress within brain involves lipid peroxidation, which generates reactive aldehydes, such as 4-hydroxynonenal (4- HNE). While 4-HNE is certainly neurotoxic and causes disruption of the blood brain barrier in case of severe injuries, it is also physiologically produced by glial cells, especially astrocytes, but its physiological roles within CNS are not understood. Because 4-HNE can regulate the response of the other cells in the body to stress, enhance their antioxidant capacities, proliferation and differentiation, we could assume that it may also have some beneficial role for neuroregeneration. Therefore, future studies on the relevance of 4-HNE for the interaction between neuronal cells, notably stem cells and reactive astrocytes might reveal novel options to better monitor and treat consequences or brain injuries, neurodegeneration and regeneration.

Breast cancer is the major cause of tumor-associated mortality in women worldwide, with prognosis depending on the early discovery of the disease and on the type of breast cancer diagnosed. Among many factors, lipids could contribute to breast cancer malignancy by participating in cellular processes. Also, aquaporins are membrane channels found aberrantly expressed in cancer tissues that were correlated with tumor aggressiveness, progression, and metastasis. However, the differences in lipid profile and aquaporin expression between cell types of different malignant potential have never been investigated. Here, we selected three breast cancer cell lines representing the three major breast cancer types (hormone positive, HER2NEUpositive, and triple negative) and analyzed their lipid profile and steady state lipid hydroperoxide levels to correlate with cell sensitivity to H2O2. Additionally, the expression profiles of AQP1, AQP3, and AQP5 and the Nrf2 transcription factor were evaluated, before and after oxidative challenge. We found that the lipid profile was dependent on the cell type, with the HER2-positive cells having the lowest level PUFA, whereas the triple negative showed the highest. However, in triple-negative cancer cells, a lower level of the Nrf2 may be responsible for a higher sensitivity to H2O2challenge. Interestingly, HER2-positive cells showed the highest increase in intracellular ROS after oxidative challenge, concomitant with a significantly higher level of AQP1, AQP3, and AQP5 expression compared to the other cell types, with AQP3 always being the most expressed isoform. The AQP3 gene expression was stimulated by H2O2treatment in hormone-positive and HER2NEUcells, together with Nrf2 expression, but was downregulated in triple-negative cells that showed instead upregulation of AQP1 and AQP5. The lipid profile and AQP gene expression after oxidative challenge of these particularly aggressive cell types may represent metabolic reprogramming of cancer cells and reflect a role in adaptation to stress and therapy resistance.

Major findings of the pilot study involving 21 critically ill patients during the week after admission to the critical care unit specialized for COVID-19 are presented. Fourteen patients have recovered, while seven passed away. There were no differences between them in respect to clinical or laboratory parameters monitored. However, protein adducts of the lipid peroxidation product 4-hydroxynonenal (HNE) were higher in the plasma of the deceased patients, while total antioxidant capacity was below the detection limit for the majority of sera samples in both groups. Moreover, levels of the HNE-protein adducts were constant in the plasma of the deceased patients, while in survivors, they have shown prominent and dynamic variations, suggesting that survivors had active oxidative stress response mechanisms reacting to COVID-19 aggression, which were not efficient in patients who died. Immunohistochemistry revealed the abundant presence of HNE-protein adducts in the lungs of deceased patients indicating that HNE is associated with the lethal outcome. It seems that HNE was spreading from the blood vessels more than being a consequence of pneumonia. Due to the limitations of the relatively small number of patients involved in this study, further research on HNE and antioxidants is needed. This might allow a better understanding of COVID-19 and options for utilizing antioxidants by personalized, integrative biomedicine approach to prevent the onset of HNE-mediated vitious circle of lipid peroxidation in patients with aggressive inflammatory diseases.

Breast cancer is still one of the leading causes of mortality in the female population. Despite the campaigns for early detection, the improvement in procedures and treatment, drastic improvement in survival rate is omitted. Discovery of aquaporins, at first described as cellular plumbing system, opened new insights in processes which contribute to cancer cell motility and proliferation. As we discover new pathways activated by aquaporins, the more we realize the complexity of biological processes and the necessity to fully understand the pathways affected by specific aquaporin in order to gain the desired outcome–remission of the disease. Among the 13 human aquaporins, AQP3 and AQP5 were shown to be significantly upregulated in breast cancer indicating their role in the development of this malignancy. Therefore, these two aquaporins will be discussed for their involvement in breast cancer development, regulation of oxidative stress and redox signalling pathways leading to possibly targeting them for new therapies.

Conventional anticancer therapies such as radiotherapy and chemotherapies are associated with oxidative stress generating reactive oxygen species (ROS) and reactive aldehydes like 4-hydroxynonenal in cancer cells that govern them to die. The main mechanism activated due to exposure of the cell to these reactive species is the Nrf2-Keap1 pathway. Although Nrf2 was firstly perceived as a tumor suppressor that inhibits tumor initiation and cancer metastasis, more recent data reveal its role also as a pro-oncogenic factor. Discovery of the upregulation of Nrf2 in different types of cancer supports such undesirable pathophysiological roles of Nrf2. The upregulation of Nrf2 leads to activation of cytoprotective genes thus helping malignant cells to withstand high levels of ROS and to avoid apoptosis, eventually becoming resistant to conventional anticancer therapy. Therefore, new treatment strategies are needed for eradication of cancer and in this review, we will explore two opposing approaches for modulation of Nrf2 in cancer treatments., Graphical abstract fx1, Highlights • Nrf2-Keap1 pathway is the main pathway activated upon redox imbalance. • Nrf2 and oxidative stress products (e.g. ROS, HNE) play dual role in carcinogenesis. • Nrf2 is both, a tumor suppressor and a proto-oncogene. • Usage of Nrf2 activators or inhibitors depends upon the stage of the cancer.

The effects of eleven 1,4-dihydropyridine derivatives (DHPs) used alone or together with prooxidant anticancer drug doxorubicin were examined on two cancer (HOS, HeLa) and two nonmalignant cell lines (HMEC, L929). Their effects on the cell growth (3H-thymidine incorporation) were compared with their antiradical activities (DPPH assay), using well-known DHP antioxidant diludine as a reference. Thus, tested DHPs belong to three groups:(1)antioxidant diludine;(2)derivatives with pyridinium moieties at position 4 of the 1,4-DHP ring;(3)DHPs containing cationic methylene onium (pyridinium, trialkylammonium) moieties at positions 2 and 6 of the 1,4-DHP ring. Diludine and DHPs of group 3 exerted antiradical activities, unlike compounds of group 2. However, novel DHPs had cell type and concentration dependent effects on3H-thymidine incorporation, while diludine did not. Hence, IB-32 (group 2) suppressed the growth of HOS and HeLa, enhancing growth of L929 cells, while K-2-11 (group 3) enhanced growth of every cell line tested, even in the presence of doxorubicin. Therefore, growth regulating and antiradical activity principles of novel DHPs should be further studied to find if DHPs of group 2 could selectively suppress cancer growth and if those of group 3 promote wound healing.

International audience; The end products of polyunsaturated fatty acid (PUFA) peroxidation, such as malondialdehyde (MDA), 4-hydroxynonenal (HNE), and isoprostanes (8-iso-PGF2alpha), are widely used as systemic lipid oxidation/oxidative stress biomarkers. However, some of these compounds have also a dietary origin. Thus, replacing dietary saturated fat by PUFAs would improve health but could also increase the formation of such compounds, especially in the case of a pro-oxidant/antioxidant imbalanced diet. Hence, the possible impact of dietary fatty acids and pro-oxidant compounds was studied in rats given diets allowing comparison of the effects of heme iron vs. ferric citrate and of omega-6- vs. omega-3-rich oil on the level of lipid peroxidation/oxidative stress biomarkers. Rats given a heme iron-rich diet without PUFA were used as controls. The results obtained have shown that MDA and the major urinary metabolite of HNE (the mercapturic acid of dihydroxynonane, DHN-MA) were highly dependent on the dietary factors tested, while 8-iso-PGF2alpha was modestly but significantly affected. Intestinal inflammation and tissue fatty acid composition were checked in parallel and could only explain the differences we observed to a limited extent. Thus, the differences in biomarkers were attributed to the formation of lipid oxidation compounds in food or during digestion, their intestinal absorption, and their excretion into urine. Moreover, fecal extracts from the rats fed the heme iron or fish oil diets were highly toxic for immortalized mouse colon cells. Such toxicity can eventually lead to promotion of colorectal carcinogenesis, supporting the epidemiological findings between red meat intake and colorectal cancer risk. Therefore, the analysis of these biomarkers of lipid peroxidation/oxidative stress in urine should be used with caution when dietary factors are not well controlled, while control of their possible dietary intake is needed also because of their pro-inflammatory, toxic, and even cocarcinogenic effects.

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed., Graphical abstract fx1, Highlights • RONS are chemical mediators and a communication tool. • RONS and disturbed redox balance play a role in a broad range of diseases and aging. • Bacteria and toxins are important stimulators of cellular RONS formation. • Drugs should preserve beneficial redox signaling and inhibit detrimental RONS sources. • Redox drugs may target the origin, identity, location and time of RONS formation.

The reactive aldehyde 4-hydroxynonenal (HNE) is major bioactive marker of lipid peroxidation generated under oxidative stress from polyunsaturated fatty acids. Biomedical significance of HNE was first revealed in pathogenesis of various degenerative and malignant diseases. Thus, HNE was considered for decades only as cytotoxic molecule, “second toxic messenger of free radicals” responsible for numerous undesirable consequences of oxidative stress. However, the increase of knowledge on physiology of redox signaling revealed also desirable, physiological roles of HNE, especially in the field of cellular signaling pathways regulating proliferation, differentiation, and apoptosis. These pluripotent effects of HNE can be explained by its concentration-dependent interactions with the cytokine networks and complex cellular antioxidant systems also showing cell and tissue specificities. Therefore, this paper gives a comprehensive, yet short overview on HNE as pluripotent growth-regulating factor.

Helicobacter pylori-induced oxidative stress in gastric mucosa (GM) is a milieu for the development of chronic gastritis, duodenal peptic ulcer (DPU), gastric cancer, and a number of extragastric diseases. Because our previous study revealed the accumulation of the protein adducts of lipid peroxidation product 4-hydroxynonenal (HNE) in GM, which persists after eradication of H. pylori, the aim of the study was to test whether Amaranth oil supplementation in addition to standard anti-Helicobacter treatment could prevent such accumulation of HNE in GM in H. pylori-positive DPU patients. Seventy-five patients were randomly split into two groups: group 1 standard treatment (n = 39) and group 2 standard treatment with additional supplementation of 1 ml of concentrated oil from amaranth seeds (Amaranthus cruenthus L., n = 36). Clinical analysis, including endoscopy with biopsies from antrum and corpus of the stomach were performed before and after the treatment, as was heart rate variability (HRV) recorded, as parameter of systemic, extragastric pathophysiological alterations in DPU patients. Improvement of clinical, endoscopic and histologic manifestations, and successful ulcer healing were observed in both the groups. Moreover, supplementation of amaranth oil in addition to standard anti-H. pylori treatment significantly reduced accumulation of HNE-histidine adducts in GM and increased HRV in DPU patients (p < .05). Therefore, standard treatments of DPU require additional therapeutic approaches, in accordance with integrative medicine principles, aiming to reduce persistence of oxidative stress, as was successfully done in our study by the use of amaranth oil.

Plasma treatment is often used to alter cell interaction with polymer surfaces used in biomedical application. The influence of surface hydrophilicity/hydrophobicity on human mammary epithelial cell (HMEC) proliferation and adhesion of protein albumin to plasma treated polystyrene (PS) was studied. The PS surface was made hydrophilic or hydrophobic by treatment either in O2 or CF4 plasma. The rate of protein adhesion was studied by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) after incubation of PS in albumin solution for different periods, while cell viability and morphology was studied by MTT assay and scanning electron microscope (SEM). XPS measurements have shown that the quantity of adsorbed protein was higher for both plasma treated samples than for the untreated one. No significant difference regarding protein adhesion on hydrophilic or hydrophobic plasma treated surface was found by XPS. Contrary, the results for cell proliferation showed much better proliferation on hydrophilic surface.

Polystyrene (PS) foils were exposed to oxygen plasma in order to improve the ability of human osteosarcoma cells (HOS) proliferation. Plasma was created in an electrodeless radio-frequency (RF) discharge in pure oxygen. Plasma treatment time of 30 s allowed for saturation of the surface with oxygen rich functional groups. Incubation of proteins from cell culture media was studied versus incubation time for untreated and plasma treated PS by X-ray photoelectron spectroscopy (XPS). Then HOS cells were cultivated according to a standard procedure, applied on the PS substrates and incubated. The proliferation was studied qualitatively by optical microscopy, scanning electron microscopy (SEM) and quantitatively by MTT assay. All techniques revealed significant differences in HOS cells proliferation on untreated and oxygen plasma treated PS. The differences were most pronounced after 24 h of incubation when the cells have already stared to proliferate on plasma treated PS, while they were still in quiescence on untreated PS. The confluency was achieved till the 6th day on plasma treated PS, while on untreated PS such confluency has never been achieved. The cell viability assay revealed that HOS cells grew better on plasma treated PS for various incubation times. Similar trend was observed regarding the adhesion of proteins. They adhered better on plasma treated PS causing better environment for further cell proliferation. The results clearly show that oxygen plasma treatment allows for much better proliferation of HOS cells on plasma treated PS as compared to the untreated PS substrates.

Bioactive glass (BG) is a highly attractive material, exhibiting both osteoinductive and osteoconductive properties, which is known to provide a growth enhancing surface for bone cells. Previous studies have shown that lipid peroxidation and in particular generation of 4-hydroxynonenal (HNE) is involved in the growth of human osteoblast-like cells, HOS, on BG. Copper (Cu), which is an essential cofactor of several enzymes as well as a proangiogenic and an antimicrobial agent, is known to induce lipid peroxidation. Therefore, the enrichment of BG with Cu could potentially have beneficial effects on the growth of the bone cells. In this study, we investigated the effects of copper-doped 45S5 BG on the growth of HOS cells and the generation of HNE. Our results confirmed the association of HNE with the growth of HOS cells. The effects of added Cu were dose-dependent. Specifically, low concentrations (i.e., 0.1% w/w) of Cu improved viability and enhanced HOS cell growth, whereas higher Cu concentrations [i.e., 2.5% and 1% (w/w)] were cytotoxic. The observed effects of Cu concentration on cell growth correlated with the level of HNE production. Therefore, Cu containing BG may represent a useful biomaterial for research and development studies of bone regeneration. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3556–3561, 2014.

Faculty of Mechanical Engineering, University of Maribor, 2000 Maribor, SloveniaReceived 23 May 2013; revised 21 July 2013; accepted 7 August 2013Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jbm.a.34911Abstract: The formation of endothelial cell monolayer onprosthetic implants has not sufficiently explored. The mainreasons leading to the development of thrombosis and=orintimal hyperplasia is the lack of endothelialization. In thepresent work, we have studied the influence of oxygen andfluorine plasma treatment of polyethylene terephthalate (PET)polymers on human microvascular endothelial cell adhesionand proliferation. We characterized the polymer surface, wett-ability, and oxidation potential upon plasma treatment. More-over, binding of serum and media compounds on PETsurface was monitored by Quartz crystal microbalancemethod, X-ray photoelectron spectroscopy, and atomic forcemicroscopy. Cell adhesion and morphology was assessed bylight and scanning electron microscopy. The influence ofplasma treatment on induction of cellular oxidative stressand cell proliferation was evaluated. The results obtainedshowed that treatment with oxygen plasma decreased theoxidation potential of the PET surface and revealed the high-est affinity for binding of serum components. Accordingly,the cells reflected the best adhesion and morphological prop-erties on oxygen-treated PET polymers. Moreover, treatmentwith oxygen plasma did not induce intracellular reactive oxy-gen species production while it stimulated endothelial cellproliferation by 25% suggesting the possible use of oxygenplasma treatment to enhance endothelialization of syntheticvascular grafts.

Otosclerosis is a complex disease characterized by an abnormal bone turnover of the otic capsule resulting in conductive hearing loss. Recent findings have shown that angiotensin II (Ang II), a major effector peptide of the renin–angiotensin system, plays an important role in the pathophysiology of otosclerosis, most likely by its proinflammatory effects on the bone cells. Because reactive oxygen species play a role both in inflammation and in the cellular signaling pathway of Ang II, the appearance of protein adducts of the “second messenger of free radicals,” the aldehyde 4-hydroxynonenal (HNE), in otosclerotic bone has been analyzed. Immunohistochemical analysis of HNE-modified proteins in tissue samples of the stapedial bones performed on 15 otosclerotic patients and 6 controls revealed regular HNE–protein adducts present in the subperiosteal parts of control bone specimens, whereas irregular areas of a pronounced HNE–protein adduct presence were found within stapedial bone in cases of otosclerosis. To study possible interference by HNE and Ang II in human bone cell proliferation, differentiation, and induction of apoptosis we used an in vitro model of osteoblast-like cells. HNE interacted with Ang II in a dose-dependent manner, both by forming HNE–Ang II adducts, as revealed by immunoblotting, and by modifying its effects on cultured cells. Namely, treatment with 0.1 nM Ang II and 2.5 μM HNE stimulated proliferation, whereas treatment with 10 μM HNE or in combination with Ang II (0.1, 0.5, and 1 nM) decreased cell proliferation. Moreover, 10 μM HNE alone and with Ang II (except if 1 nM Ang II was used) increased cellular differentiation and apoptosis. HNE at 5 μM did not affect differentiation nor significantly change apoptosis. On the other hand, when cells were treated with lower concentrations of HNE and Ang II we observed a decrease in cellular differentiation (combination of 1.0 or 2.5 μM HNE with 0.1 nM Ang II) and decrease in apoptosis (0.1 and 0.5 nM Ang II). Cellular necrosis was increased with 5 and 10 μM HNE if given alone or combined with Ang II, whereas 0.5 nM Ang II and combination of 1 μM HNE with Ang II (0.1 and 0.5 nM) reduced necrosis. These results indicate that HNE and Ang II might act mutually dependently in the regulation of bone cell growth and in the pathophysiology of otosclerosis.

While reactive oxygen species (ROS) gain their carcinogenic effects by DNA mutations, if generated in the vicinity of genome, lipid peroxidation products, notably 4-hydroxynonenal (HNE), have much more complex modes of activities. Namely, while ROS are short living and have short efficiency distance range (in nm or µm) HNE has strong binding affinity for proteins, thus forming relatively stable adducts. Hence, HNE can diffuse from the site or origin changing structure and function of respective proteins. Consequently HNE can influence proliferation, differentiation and apoptosis of cancer cells on one hand, while on the other it can affect genome functionality, too. Although HNE is considered to be important factor of carcinogenesis due to its ability to covalently bind to DNA, it might also be cytotoxic for cancer cells, as well as it can modulate their growth. In addition to direct cytotoxicity, HNE is also involved in activity mechanisms by which several cytostatic drugs and radiotherapy exhibit their anticancer effects. Complementary to that, the metabolic pathway for HNE detoxification through RLIP76, which is enhanced in cancer, may be a target for anti-cancer treatments. In addition, some cancer cells can undergo apoptosis or necrosis, if exposed to supraphysiological HNE levels in the cancer microenvironment, especially if challenged additionally by pro-oxidative cytostatics and/or inflammation. These findings could explain previously observed disappearance of HNE from invading cancer cells, which is associated with the increase of HNE in non- malignant cells close to invading cancer utilizing cardiolipin as the source of cancer-inhibiting HNE.

Cancer stem cells are a subpopulation of cancer cells with great plasticity, slow cell cycle and are capable of dormating for long time. Today, these cells are recognized as a major factor of malignancy causing metastasis, relapse, failure of cancer treatment and therapy resistance. The mechanisms which keep in control or activate these cells are still not fully revealed, but microenvironment certainly has a specific role. Proteins of the extracellular matrix can modify proccesses which cells are undergoing and changes of these proteins consequently affect cell. In addition to the environmental signals, oxidative stress may modulate and change signals cells are recieving thereby creating different outcome. Among the molecules produced during oxidative stress, 4-hydroxynonenal (HNE) was shown to modulate many signaling pathways thereby inducing differentiation, proliferation or apoptosis. Here, we provide evidence that HNE can change cancer stem cell responce to chronic oxidative stress through interactions with collagen, representative of extracellular matrix protein. Hence, HNE may be the factor that modulates cellular responce to stress or therapy via interactions with extracellular proteins and thereby changing the outcome of the disease.

Oxidative stress is an important factor in carcinogenesis. In addition, radiotherapy, chemotherapy and inflammation increase oxidative stress in tumors. Lipid peroxidation end product, a reactive aldehyde 4-hydroxy-2-nonenal (HNE), is considered to be second messenger of oxidative stress. HNE modifies the metabolism of cancer cells by interacting with proteins, lipids and DNA. Along with oxidative stress, cancer stem cells have been recognized as the crucial factor in cancer malignancy and are considered responsible for metastasis occurrence, therapy resistance and, finally, recurrence of the disease. For these reasons we examined the effect of HNE induced oxidative stress and HNE modulation of the extracellular matrix on cancer stem cells metabolism, proliferation and their antioxidative mechanisms. Collagen was used as a representative protein of extracellular matrix and was modified with HNE. Cells were plated on native and HNE-modified collagen as well as polystyrene surface and were additionally treated with HNE every second day. Afterwards, we determined viability and proliferation with MTT and 3HT test. Antioxidant cell capacity was assessed by glutathione and catalase assay. Dot-blot analysis was performed in order to quantify Nrf2 and HNE histidine conjugates. We confirmed specificity of dot-blot findings by performing western blot analysis of Nrf2. The results suggest that the aggressive cancer stem cell phenotype is enhanced during chronic oxidative stress. Extracellular matrix alterations resulting from oxidative stress may cause an adaptation of cancer stem cells, enabling them to survive increased oxidative stress.

Oxidative stress is often considered as a causative factor in carcinogenesis. In addition, current knowledge recognizes oxidative stress as a mechanism by which various cancer therapies act against cancer. To ameliorate the side effects of cancer therapy, many of the patients suffering from cancer are subject to adjuvant therapy, which often implies antioxidant supplementation. Yet, the benefits of such adjuvant treatments are still uncertain owing to the lack of appropriate integrative and personalized medical approach. In particular, reactive oxygen species formed during oxidative stress and products of lipid peroxidation are not only cytotoxic, but can modulate signal transduction in cells, which also behave similar to individuals under stress. Accordingly, pro-oxidants and antioxidants might be considered as modifiers of specific cellular redox signaling. Therefore, there is a need to evaluate the potential benefits of antioxidant supplements in healthy persons, and in particular in cancer patients during therapy. Our review will present a summary of the existing knowledge regarding the effects of various antioxidants in cancer therapies, focusing on cellular adaptation to oxidative stress interacting with redox signaling transduction pathways thereby influencing cell growth.

The reactive aldehyde, 4-hydroxynonenal (HNE), is recognized as a product of lipid peroxidation, which binds to macromolecules, in particular proteins. HNE-modified proteins (HNE-MP) have been shown to accumulate during ageing, generally by using polyclonal antibodies, which increase the possibility of detecting false positives. Therefore, we have used a genuine monoclonal antibody specific for HNE-His adducts of proteins/peptides, which were revealed by immunoblotting method for whole-cell HNE-MP measurements in serially passaged human facial skin fibroblasts undergoing ageing in vitro. There was a significant increase in the levels of HNE-MP in serially passaged cells approaching a near senescent state at high passage level (P-61), as compared with low passage level (P-11) young and middle-aged (P-27) cells. However, if the cells were analyzed soon after re-initiation from the frozen samples with little further passaging, the amount of HNE-MP was low even in relatively high passage level (P-37) cells, which is an indication of selective elimination of cells with high molecular damage during the process of thawing and re-initiation in culture. This pilot study on normal human facial skin fibroblasts shows that HNE-MP detection by monoclonal antibody-based dot blot method can be used as a marker for age-related accumulation of lipid peroxidative molecular damage, and could be useful for testing and monitoring the effects of potential skin care products on ageing parameters.

Bioactive glass (BG) is a highly attractive material, exhibiting both osteoinductive and osteoconductive properties, which is known to provide a growth enhancing surface for bone cells. Previous studies have shown that lipid peroxidation and in particular generation of 4-hydroxynonenal (HNE) is involved in the growth of human osteoblast-like cells, HOS, on BG. Copper (Cu), which is an essential cofactor of several enzymes as well as a proangiogenic and an antimicrobial agent, is known to induce lipid peroxidation. Therefore, the enrichment of BG with Cu could potentially have beneficial effects on the growth of the bone cells. In this study, we investigated the effects of copper-doped 45S5 BG on the growth of HOS cells and the generation of HNE. Our results confirmed the association of HNE with the growth of HOS cells. The effects of added Cu were dose-dependent. Specifically, low concentrations (i.e., 0.1% w/w) of Cu improved viability and enhanced HOS cell growth, whereas higher Cu concentrations [i.e., 2.5% and 1% (w/w)] were cytotoxic. The observed effects of Cu concentration on cell growth correlated with the level of HNE production. Therefore, Cu containing BG may represent a useful biomaterial for research and development studies of bone regeneration.

The formation of endothelial cell monolayer on prosthetic implants has not sufficiently explored. The main reasons leading to the development of thrombosis and/or intimal hyperplasia is the lack of endothelialization. In the present work, we have studied the influence of oxygen and fluorine plasma treatment of polyethylene terephthalate (PET) polymers on human microvascular endothelial cell adhesion and proliferation. We characterized the polymer surface, wettability, and oxidation potential upon plasma treatment. Moreover, binding of serum and media compounds on PET surface was monitored by Quartz crystal microbalance method, X-ray photoelectron spectroscopy, and atomic force microscopy. Cell adhesion and morphology was assessed by light and scanning electron microscopy. The influence of plasma treatment on induction of cellular oxidative stress and cell proliferation was evaluated. The results obtained showed that treatment with oxygen plasma decreased the oxidation potential of the PET surface and revealed the highest affinity for binding of serum components. Accordingly, the cells reflected the best adhesion and morphological properties on oxygen-treated PET polymers. Moreover, treatment with oxygen plasma did not induce intracellular reactive oxygen species production while it stimulated endothelial cell proliferation by 25% suggesting the possible use of oxygen plasma treatment to enhance endothelialization of synthetic vascular grafts.

Alterations in the intestinal barrier permeability occur in a broad spectrum of abdominally related pathologies, mostly due to disturbed oxidative homeostasis and increased lipid peroxidation. 4-Hydroxynonenal (HNE), a major lipid peroxidation product, is physiologically present in healthy gastric mucosa, but is increased in early stages of colon cancer and patients with duodenal peptic ulcer. Nevertheless, such supraphysiological levels of HNE have not yet been associated with increased intestinal permeability, even though, as we have described in this paper, they could play important role. In vitro model of intestinal barrier was established by growing Caco-2 cell line on cell culture permeable inserts. The pyridoindole derivative stobadine in hydrophilic and lipophilic form was used for barrier model protection. Both forms of stobadine were able to prevent damaging HNE effects, and reduce generation of reactive oxygen species and permeability of the intestinal barrier. Immunocytochemical analysis has confirmed beneficial effect of stobadine in reducing the formation of HNE-protein conjugates in the cells. Lipophilic form of stobadine proved to be more efficient than hydrophilic, implying importance of lipids in maintaining barrier function. The results obtained indicate that HNE might be important factor affecting intestinal barrier integrity, while stobadine could efficiently protect intestinal cells against harmful HNE effects.

Adhesion of human osteosarcoma (HOS) cells on hydrophobic polymer surface was studied. Surface of polymer polystyrene (PS) was made hydrophobic by treatment in plasma created in tetrafluoromethane gas (CF4). The PS samples were exposed for 30 s to CF4 plasma created by RF generator powered at 200 W. This treatment time allowed for optimal polymer surface functionalization with fluorine functional groups. This caused an increase of surface hydrophobicity from initial 85° to about 110° as measured by water contact angle. The HOS cells were deposited on untreated and plasma treated samples and incubated for 1, 2 and 6 days. Both untreated and plasma treated samples were tested for biocompatibility by two different methods: optical micrographs were used to study the cell morphology and MTT test was used to study the cell viability. The results showed better adhesion of cells on plasma treated samples with more hydrophobic surface in comparison to the untreated sample. MTT test revealed about 1.6-times higher activity of cell enzymes after 6-day incubation for plasma treated sample. Optical micrographs have shown that both untreated and fluorine-plasma treated polymer surfaces are not optimal for cell proliferation, since cells need about 2 days to adapt to the surface. After this adaptation time cells start to proliferate on the polymer surface, especially, on that one treated in plasma.