Lipid peroxidation product acrolein as a predictive biomarker of prostate carcinoma relapse after radical surgery

Adipose Tissues Have Been Overlooked as Players in Prostate Cancer Progression

Obesity is a common risk factor in multiple tumor types, including prostate cancer. Obesity has been associated with driving metastasis, therapeutic resistance, and increased mortality. The effect of adipose tissue on the tumor microenvironment is still poorly understood. This review aims to highlight the work conducted in the field of obesity and prostate cancer and bring attention to areas where more research is needed. In this review, we have described key differences between healthy adipose tissues and obese adipose tissues, as they relate to the tumor microenvironment, focusing on mechanisms related to metabolic changes, abnormal adipokine secretion, altered immune cell presence, and heightened oxidative stress as drivers of prostate cancer formation and progression. Interestingly, common treatment options for prostate cancer ignore the adipose tissue located near the site of the tumor. Because of this, we have outlined how excess adipose tissue potentially affects therapeutics' efficacy, such as androgen deprivation, chemotherapy, and radiation treatment, and identified possible drug targets to increase prostate cancer responsiveness to clinical treatments. Understanding how obesity affects the tumor microenvironment will pave the way for understanding why some prostate cancers become metastatic or treatment-resistant, and why patients experience recurrence.

Relationship between 4-Hydroxynonenal (4-HNE) as Systemic Biomarker of Lipid Peroxidation and Metabolomic Profiling of Patients with Prostate Cancer

An oxidative degradation product of the polyunsaturated fatty acids, 4-hydroxynonenal (4-HNE), is of particular interest in cancer research due to its concentration-dependent pleiotropic activities affecting cellular antioxidants, metabolism, and growth control. Although an increase in oxidative stress and lipid peroxidation was already associated with prostate cancer progression a few decades ago, the knowledge of the involvement of 4-HNE in prostate cancer tumorigenesis is limited. This study investigated the appearance of 4-HNE-protein adducts in prostate cancer tissue by immunohistochemistry using a genuine 4-HNE monoclonal antibody. Plasma samples of the same patients and samples of the healthy controls were also analyzed for the presence of 4-HNE-protein adducts, followed by metabolic profiling using LC-ESI-QTOF-MS and GC-EI-Q-MS. Finally, the analysis of the metabolic pathways affected by 4-HNE was performed. The obtained results revealed the absence of 4-HNE-protein adducts in prostate carcinoma tissue but increased 4-HNE-protein levels in the plasma of these patients. Metabolomics revealed a positive association of different long-chain and medium-chain fatty acids with the presence of prostate cancer. Furthermore, while linoleic acid positively correlated with the levels of 4-HNE-protein adducts in the blood of healthy men, no correlation was obtained for cancer patients indicating altered lipid metabolism in this case. The metabolic pathway of unsaturated fatty acids biosynthesis emerged as significantly affected by 4-HNE. Overall, this is the first study linking 4-HNE adduction to plasma proteins with specific alterations in the plasma metabolome of prostate cancer patients. This study revealed that increased 4-HNE plasma protein adducts could modulate the unsaturated fatty acids biosynthesis pathway. It is yet to be determined if this is a direct result of 4-HNE or whether they are produced by the same underlying mechanisms. Further mechanistic studies are needed to grasp the biological significance of the observed changes in prostate cancer tumorigenesis.

Critical Review on Fatty Acid-Based Food and Nutraceuticals as Supporting Therapy in Cancer

Fatty acids have an important place in both biological and nutritional contexts and, from a clinical point of view, they have known consequences for diseases’ onset and development, including cancer. The use of fatty acid-based food and nutraceuticals to support cancer therapy is a multidisciplinary subject, involving molecular and clinical research. Knowledge regarding polyunsaturated fatty acids essentiality/oxidizability and the role of lipogenesis-desaturase pathways for cell growth, as well as oxidative reactivity in cancer cells, are discussed, since they can drive the choice of fatty acids using their multiple roles to support antitumoral drug activity. The central role of membrane fatty acid composition is highlighted for the application of membrane lipid therapy. As fatty acids are also known as biomarkers of cancer onset and progression, the personalization of the fatty acid-based therapy is also possible, taking into account other important factors such as formulation, bioavailability and the distribution of the supplementation. A holistic approach emerges combining nutra- and pharma-strategies in an appropriate manner, to develop further knowledge and applications in cancer therapy.

The Potential Role of Mitochondrial Acetaldehyde Dehydrogenase 2 in Urological Cancers From the Perspective of Ferroptosis and Cellular Senescence

Overproduction of reactive oxygen species (ROS) and superlative lipid peroxidation promote tumorigenesis, and mitochondrial aldehyde dehydrogenase 2 (ALDH2) is associated with the detoxification of ROS-mediated lipid peroxidation-generated reactive aldehydes such as 4-hydroxy-2-nonenal (4-HNE), malondialdehyde, and acrolein due to tobacco smoking. ALDH2 has been demonstrated to be highly associated with the prognosis and chemoradiotherapy sensitivity of many types of cancer, including leukemia, lung cancer, head and neck cancer, esophageal cancer, hepatocellular cancer, pancreatic cancer, and ovarian cancer. In this study, we explored the possible relationship between ALDH2 and urological cancers from the aspects of ferroptosis, epigenetic alterations, proteostasis, mitochondrial dysfunction, and cellular senescence.

The Appearance of 4-Hydroxy-2-Nonenal (HNE) in Squamous Cell Carcinoma of the Oropharynx

Tumor growth is associated with oxidative stress, which causes lipid peroxidation. The most intensively studied product of lipid peroxidation is 4-hydroxy-2-nonenal (HNE), which is considered as a “second messenger of free radicals” that binds to proteins and acts as a growth-regulating signaling factor. The incidence of squamous cell carcinoma of the oropharynx is associated with smoking, alcohol and infection of human papilloma virus (HPV), with increasing incidence world-wide. The aim of this retrospective study involving 102 patients was to determine the immunohistochemical appearance of HNE-protein adducts as a potential biomarker of lipid peroxidation in squamous cell carcinoma of the oropharynx. The HNE-protein adducts were detected in almost all tumor samples and in the surrounding non-tumorous tissue, while we found that HNE is differentially distributed in squamous cell carcinomas in dependence of clinical stage and histological grading of these tumors. Namely, the level of HNE-immunopositivity was increased in comparison to the normal oropharyngeal epithelium in well- and in moderately-differentiated squamous cell carcinoma, while it was decreasing in poorly differentiated carcinomas and in advanced stages of cancer. However, more malignant and advanced cancer was associated with the increase of HNE in surrounding, normal tissue. This study confirmed the onset of lipid peroxidation, generating HNE-protein adducts that can be used as a valuable bioactive marker of carcinogenesis in squamous cell carcinoma of the oropharynx, as well as indicating involvement of HNE in pathophysiological changes of the non-malignant tissue in the vicinity of cancer.

Identification of Differential Patterns of Oxidative Biomarkers in Prostate Cancer Progression

INTRODUCTION

Oxidative stress has been found to be associated with the progression of prostate cancer (PCa); however, human studies which identify differential roles of each oxidation pathway in PCa progression are lacking. We aimed to identify which oxidative stress markers, specifically lipid and global oxidation and glycation, are associated with PCa progression.

PATIENTS AND METHODS

We recruited 3 groups of patients from a urologic clinic at the University of Cincinnati Medical Center: men with PCa who had undergone prostatectomy, men with PCa under watchful waiting, and men with benign prostatic hyperplasia (BPH). We used the most commonly used lipid oxidation marker, F2-isoprostanes; global oxidation markers, fluorescent oxidation products (FlOPs); and the commonly used marker for advanced glycation end products, carboxymethyllysine. These biomarkers were measured in plasma samples at baseline entry. Plasma prostate-specific antigen (PSA) was measured at enrollment and follow-up visits.

RESULTS

Compared with men with BPH, men with PCa who had undergone prostatectomy had 26% (P = .01) higher levels of F2-isoprostanes and 20% (P = .08) higher levels of carboxymethyllysine. All the oxidation markers were similar when comparing men under watchful waiting with men with BPH. When examining the associations between baseline oxidation markers and follow-up PSAs, we found that different oxidation markers had differential patterns associated with PSA elevation. F2-isoprostanes were positively associated with PSA elevation among men with PCa; FlOP_320 was positively associated with PSA elevation among both men with PCa and men with BPH, whereas among men with PCa under watchful waiting, FlOP_360 and FlOP_400 had opposite trends of associations with PSA elevation.

CONCLUSIONS

Our study suggested that high levels of lipid oxidation were associated with PCa progression, whereas different global oxidation markers had different patterns associated with PCa progression. Large-scale clinical studies are needed to confirm our associations. Our study provides a comprehensive view of the relationship between biomarkers and PCa progression.

Lipoxidation and cancer immunity

Lipoxidation is a well-known reaction between electrophilic carbonyl species, formed during oxidation of lipids, and specific proteins that, in most cases, causes an alteration in proteins function. This can occur under physiological conditions but, in many cases, it has been associated to pathological process, including cancer. Lipoxidation may have an effect in cancer development through their effects in tumour cells, as well as through the alteration of immune components and the consequent modulation of the immune response. The formation of protein adducts affects different proteins in cancer, triggering different mechanism, such as proliferation, cell differentiation and apoptosis, among others, altering cancer progression. The divergent results obtained documented that the formation of lipoxidation adducts can have either anti-carcinogenic or pro-carcinogenic effects, depending on the cell type affected and the specific adduct formed. Moreover, lipoxidation adducts may alter the immune response, consequently causing either positive or negative alterations in cancer progression. Therefore, in this review, we summarize the effects of lipoxidation adducts in cancer cells and immune components and their consequences in the evolution of different types of cancer.

Contribution of the HNE-immunohistochemistry to modern pathological concepts of major human diseases

Excessive production of reactive oxygen species can induce peroxidation of the polyunsaturated fatty acids thus generating reactive aldehydes like 4-hydroxy-2-nonenal (HNE), denoted as "the second messenger of free radicals". Because HNE has high binding affinity for cysteine, histidine and lysine it forms relatively stable and hardly metabolized protein adducts. By changing structure and function of diverse structural and regulatory proteins, HNE achieves not only cytotoxic, but also regulatory functions in various pathophysiological processes. Numerous animal model studies and clinical trials confirmed HNE as one of the crucial factors in development and progression of many disorders, in particular of cancer, (neuro)degenerative, metabolic and inflammatory diseases. Since HNE has multiple biological effects and is in the living system usually bound to proteins and peptides, many research groups work on development of specific immunochemical methods targeting the HNE-histidine adducts as major bioactive marker of lipid peroxidation, following the research pathway initiated by Hermann Esterbauer, who discovered HNE in 60's. Such immunohistochemical studies did not only prove the high biomedical importance of HNE, but have also given new insights into major diseases of the modern man. Immunohistochemical studies have shown reversibility of formation of the HNE-protein adducts, as well as differential onset of the HNE-mediated lipid peroxidation between age- associated atherosclerosis and photoaging, revealing eventually selective anti-cancer effects of HNE produced by non-malignant cells in vicinity of cancer. This review summarizes some of the HNE-histidine immunohistochemistry findings we believe are of broad biomedical interest and could inspire new studies in the field.

Lipid mediators involved in the oxidative stress and antioxidant defence of human lung cancer cells

Background

The oxidative modifications of bioactive macromolecules have important roles in carcinogenesis. Of particular interest are lipid peroxidation products, which are involved in the activation of Nrf2 and endocannabinoids that affect cancer progression.

Methods

In lung cancer tissues (squamous cell lung carcinoma - SCC and adenocarcinoma - AC), the glutathione peroxidase and catalase activity and glutathione level, together with the expression of Nrf2 and its activators/inhibitors were estimated. The oxidative modifications of DNA (8-hydroxy-2′-deoxyguanosine and N7-methylguanine), endocannabinoids (anandamide and 2- arachidonylglyceriol), their receptors (CB1/2, TRV1, GPR55), phospholipid fatty acids (arachidonic, linoleic and docosahexaenoic), and reactive aldehydes (4-hydroxynonenal, 4-oxononenal and malondialdehyde) were determined.

Results

Tumour tissues showed lower antioxidant capacity than healthy tissues, which was accompanied by lower levels of fatty acids and higher levels of reactive aldehydes. Disturbances in antioxidant capacity and enhanced DNA oxidative modifications were observed in 88% of AC patients and 81% of SCC patients. The 4-hydroxynonenal-Histidine adducts were detected in the necrotic and stromal cells in all tumours. These findings were associated with the enhanced Nrf2 activity, especially in AC. The strong difference between the cancer subtypes was evident in the levels of endocannabinoids, with an increase in 89% of SCC and a decrease in 85% of AC patients being observed. Additionally, the increase in the expression of CB1/2 receptors was observed only in 82% of AC, while the expression of VR1 and GPR55 was enhanced in 79% of SCC and 82% of AC patients.

Conclusions

This study shows significant differences in the redox status, Nrf2 pathway and endocannabinoid system between SCC and AC tissues. Understanding the relation between the various lipid mediators and antioxidants in different lung cancer subtypes may be beginning for further research on the effective anticancer therapy.

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AC tissues show lower antioxidant capacity than SCC.

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Nrf2/ARE pathway is activated stronger in AC than in SCC.

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AC exhibits more lipid oxidative modifications than SCC.

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HNE-protein adducts are detected in the necrotic and stromal cells in SCC and AC.

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SCC exhibits increase in endocannabinoids level while in AC reverse effect is observed.

Prostate cancer and physical activity: adaptive response to oxidative stress

Prostate cancer is the most common form of cancer affecting men in the Western world. Its relative incidence increases exponentially with age and a steady increase is observed with extended life span. A sedentary lifestyle represents an important risk factor and a decrease in prostate cancer prevalence is associated with exercise. However, the molecular mechanisms involved in this process remain unknown. We hypothesize that reactive oxygen species generated by physical exercise are a key regulatory factor in prostate cancer prevention. Aging is correlated with increased oxidative stress (OS), which in turn provides a favorable environment for tumorigenesis. Running training is known to enhance the antioxidant defense system, reducing oxidative stress. In this context, the decrease in OS induced by exercise may delay the development of prostate cancer. This review focuses on oxidative stress-based mechanisms leading to prostate cancer sensitization to exercise, which could have some impact on the development of novel cancer therapeutic strategies.

Even stressed cells are individuals: second messengers of free radicals in pathophysiology of cancer

Abstract

Pathophysiological processes associated with disturbances in cell and tissue oxidative homeostasis, are associated with self-catalyzed process of lipid peroxidation. The end products of lipid peroxidation are reactive aldehydes such as 4-hydroxy-2-nonenal (HNE), acting as “second messengers of free radicals.” Although reactive aldehydes were first recognized only as cytotoxic, new evidence has come to light, related to their cell growth regulatory functions achieved through cell signaling. The variable appearance of HNE in several organs indicates that its mode of action might be related to an individual cell stress adaptation. The underlying mechanism could be that specific mutations and epigenetic changes on one hand interfere with hormesis on the other. The precise role of oxidative stress and lipid peroxidation in these processes still needs more clarification at molecular level. Finally, an individual approach to each patient, based on the individual cell response to stress, opens a new possibility of integrative medicine in cancer treatment and strongly supports modern concepts of personalized medicine.

Pathophysiological relevance of aldehydic protein modifications

There is growing body of evidence that oxidative stress, i.e. excess in production of reactive oxygen species, can lead to covalent modification of proteins with bioactive aldehydes that are mostly produced under lipid peroxidation of polyunsaturated fatty acids. Thus generated reactive aldehydes are considered as second messengers of free radicals because they react with major bioactive macromolecules, in particular with various humoral and cellular proteins changing their structure and functions. Therefore, the aldehydic-protein adducts, in particular those involving 4-hydroxy-2-nonenal, malondialdehyde and acrolein can be valuable biomarkers of numerous pathophysiological processes. The development of immunochemical methods is increasing the possibilities to study such non-enzymatic protein modifications, on the one hand, while on the other hand the increase of knowledge on bioactivities of the aldehydes and their protein adducts might lead to better prevention, diagnosis and treatments of pathophysiological processes associated with lipid peroxidation and oxidative stress in general. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.

Effects of bioreactive acrolein from automotive exhaust gases on human cells in vitro

Acrolein is a toxic unsaturated aldehyde and widespread environmental pollutant produced during lipid peroxidation and also by burning of tobacco or liquid fuels. Inhalation or dermal exposure to acrolein could be toxic to organisms. This very reactive aldehyde has a strong affinity for binding to proteins thus forming pathogenic protein-adducts. In the present study we have analyzed formation of bioreactive acrolein-protein adducts in bovine serum albumin solution exposed to exhaust gases of mineral diesel fuel and of mineral diesel fuel supplemented with different amounts of a novel diesel fuel additive denoted Ecodiesel (produced by a genuine procedure of recycling of plant oils used for food preparation). The effects of acrolein-protein adducts were tested on human microvascular endothelial cells and on human osteosarcoma cells that are sensitive to bioactivities of lipid peroxidation products. The results have shown a reduction of the bioreactive acrolein in exhaust gases when mineral diesel was supplemented with 5-20% Ecodiesel. Moreover, acrolein-protein adducts obtained from mineral diesel supplemented with Ecodiesel were less toxic than those obtained from mineral diesel alone. Thus, we assume that supplementing mineral diesel fuel with Ecodiesel would be of benefit for the use of renewable energy, for environment and for human health due to reduced environmental pollution with bioreactive acrolein.

Mass spectrometry-based quantification of myocardial protein adducts with acrolein in an in vivo model of oxidative stress

Acrolein (ACR) exposure leads to the formation of protein-ACR adducts. Protein modification by ACR has been associated with various chronic diseases including cardiovascular and neurodegenerative diseases. Here, we report an analytical strategy that enables the quantification of Michael-type protein adducts of ACR in mitochondrial proteome samples using liquid chromatography in combination with tandem mass spectrometry and selected ion monitoring (LC-MS/MS SRM) analysis. Our approach combines site-specific identification and relative quantification at the peptide level of protein-ACR adducts in relation to the unmodified protein thiol pool. Treatment of 3-month-old rats with CCl(4) , an established in vivo model of acute oxidative stress, resulted in significant increases in the ratios of distinct ACR-adducted peptides to the corresponding unmodified thiol-peptides obtained from proteins that were isolated from cardiac mitochondria. The mitochondrial proteins that were found adducted by ACR were malate dehydrogenase, NADH dehydrogenase [ubiquinone] flavoprotein 1, cytochrome c oxidase subunit VIb isoform 1, ATP synthase d chain, and ADP/ATP translocase 1. The findings indicate that protein modification by ACR has potential value as an index of mitochondrial oxidative stress.

Protein modification by acrolein: relevance to pathological conditions and inhibition by aldehyde sequestering agents

Acrolein (ACR) is a toxic and highly reactive α,β-unsaturated aldehyde widely distributed in the environment as a common pollutant and generated endogenously mainly by lipoxidation reactions. Its biological effects are due to its ability to react with the nucleophilic sites of proteins, to form covalently modified biomolecules which are thought to be involved as pathogenic factors in the onset and progression of many pathological conditions such as cardiovascular and neurodegenerative diseases. Functional impairment of structural proteins and enzymes by covalent modification (crosslinking) and triggering of key cell signalling systems are now well-recognized signs of cell and tissue damage induced by reactive carbonyl species (RCS). In this review, we mainly focus on the in vitro and in vivo evidence demonstrating the ability of ACR to covalently modify protein structures, in order to gain a deeper insight into the dysregulation of cellular and metabolic pathways caused by such modifications. In addition, by considering RCS and RCS-modified proteins as drug targets, this survey will provide an overview on the newly developed molecules specifically tested for direct or indirect ACR scavenging, and the more significant studies performed in the last years attesting the efficacy of compounds already recognized as promising aldehyde-sequestering agents.

Pathological aspects of lipid peroxidation

Lipid peroxidation (LPO) product accumulation in human tissues is a major cause of tissular and cellular dysfunction that plays a major role in ageing and most age-related and oxidative stress-related diseases. The current evidence for the implication of LPO in pathological processes is discussed in this review. New data and literature review are provided evaluating the role of LPO in the pathophysiology of ageing and classically oxidative stress-linked diseases, such as neurodegenerative diseases, diabetes and atherosclerosis (the main cause of cardiovascular complications). Striking evidences implicating LPO in foetal vascular dysfunction occurring in pre-eclampsia, in renal and liver diseases, as well as their role as cause and consequence to cancer development are addressed.