Serum oxidized protein and prostate cancer risk within the Prostate Cancer Prevention Trial

Oxidative Stress Links Aging-Associated Cardiovascular Diseases and Prostatic Diseases

The incidence of chronic aging-associated diseases, especially cardiovascular and prostatic diseases, is increasing with the aging of society. Evidence indicates that cardiovascular diseases usually coexist with prostatic diseases or increase its risk, while the pathological mechanisms of these diseases are unknown. Oxidative stress plays an important role in the development of both cardiovascular and prostatic diseases. The levels of oxidative stress biomarkers are higher in patients with cardiovascular diseases, and these also contribute to the development of prostatic diseases, suggesting cardiovascular diseases may increase the risk of prostatic diseases via oxidative stress. This review summarizes the role of oxidative stress in cardiovascular and prostatic diseases and also focuses on the main shared pathways underlying these diseases, in order to provide potential prevention and treatment targets.

Redox changes in obesity, metabolic syndrome, and diabetes

"Life is an instantaneous encounter of circulating matter and flowing energy" (Jean Giaja, Serbian physiologist), is one of the most elegant definitions not only of life but the relationship of redox biology and metabolism. Their evolutionary liaison has created inseparable yet dynamic homeostasis in health, which, when disrupted, leads to disease. This interconnection is even more pertinent today, in an era of increasing metabolic diseases of epidemic proportions such as obesity, metabolic syndrome, and diabetes. Despite great advances in understanding the molecular mechanisms of redox and metabolic regulation, we face significant challenges in preventing, diagnosing, and treating metabolic diseases. The etiological association and temporal overlap of these syndromes present significant challenges for the discrimination of appropriate clinical biomarkers for diagnosis, treatment, and outcome prediction. These multifactorial, multiorgan metabolic syndromes with complex etiopathogenic mechanisms are accompanied by disturbed redox equilibrium in target tissues and circulation. Free radicals and reactive species are considered both a causal factor and a consequence of disease status. Thus, determining the subtypes and levels of free radicals and reactive species, oxidatively damaged biomolecules (lipids, proteins, and nucleic acids) and antioxidant defense components as well as redox-sensitive transcription factors and fluxes of redox-dependent metabolic pathways will help define existing and establish novel redox biomarkers for stratifying metabolic diseases. This review aims to discuss diverse redox/metabolic aspects in obesity, metabolic syndrome, and diabetes, with the imperative to help establish a platform for emerging and future redox-metabolic biomarkers research in precision medicine. Future research warrants detailed investigations into the status of redox biomarkers in healthy subjects and patients, including the use of emerging 'omic' profiling technologies (e.g., redox proteomes, lipidomes, metabolomes, and transcriptomes), taking into account the influence of lifestyle (diet, physical activity, sleep, work patterns) as well as circadian ~24h fluctuations in circulatory factors and metabolites.

Xanthine Oxidase/Dehydrogenase Activity as a Source of Oxidative Stress in Prostate Cancer Tissue

Prostate cancer (PC) is one of the most frequent malignancies. Better biomarkers are constantly wanted, such as those which can help with the prediction of cancer behavior. What is also needed is a marker which may serve as a possible therapeutic target. Oxidative stress (OS), which is a hallmark of cancer, is included in the pathogenesis and progression of PC. We have conducted the present study to determine whether xanthine oxidase/dehydrogenase activity is the source of OS in prostate tissue. We have also determined the concentration of TBA-reactive substances (TBARS) and advanced oxidation protein products (AOPP), as well as the activity of catalase. Xanthine oxidase (XO) activity is significantly higher (p < 0.001) in tumor tissue when compared to the control healthy tissue. The concentration of TBARS (p < 0.001) and AOPP (p < 0.05) are also higher in tumor tissue. Catalase has raised its activity (p < 0.05) versus the control. There is also a strong correlation between XO activity and prostate-specific antigen (PSA) levels in the serum. These results indicate a significant role of XO activity in OS in prostate carcinogenesis, and it could be a possible theranostic biomarker, which can be important for a better understanding of the disease, its evolution, and prognosis. A promising treatment may be using XO inhibitors such as allopurinol as adjuvant therapy.

Thiol Groups as a Biomarker for the Diagnosis and Prognosis of Prostate Cancer

Oxidative stress (OS) is associated with the onset of prostate cancer (PCa). The aims of this study are to examine whether OS biomarkers may be employed as external validating criteria for the diagnosis PCa. This case-control study recruited 204 subjects, 73 patients with PCa, 67 patients with benign prostate hyperplasia (BPH), and 64 healthy controls (HC) and assayed plasma prostate-specific antigen (PSA), protein thiol (−SH) groups, lipid hydroperoxides, carbonyl proteins (PCB), advanced oxidation protein products (AOPP), and total radical-trapping antioxidant parameter (TRAP). -SH groups were significantly and inversely associated with PSA levels. PCa was characterized by lowered -SH groups and red blood cell TRAP levels, and higher PSA, AOPP and PCB levels as compared with BPH and HC. Support vector machine with 10-fold cross-validation showed that PSA values together with -SH groups, PCB and AOPP yielded a cross-validation accuracy of 96.34% for the differentiation of PCa from BPH and HC. The area under the ROC curve using PSA and -SH differentiating PCa from BPH and controls was 0.945. Moreover, lowered -SH, but not PSA, are associated with PCa metastasis and progression. Inflammatory biomarkers were not associated with PCa or BPH. PCa, its progression and metastatic PCa are characterized by lowered antioxidant defenses, especially lowered thiol groups, and increased oxidative stress toxicity, suggesting that these processes play a key role in the pathophysiology of PCa. An algorithm based on -SH and PSA values may be used to differentiate patients with PCa from those with BPH and controls.

Oxidative stress in prostate cancer patients: A systematic review of case control studies

BACKGROUND

Prostate cancer (PCa) is the most common cancer in men in Western countries. In-vitro and in-vivo studies suggest that oxidative stress (OS) and antioxidants play a key role in the pathogenesis of chronic diseases including PCa, which is promoted by the production of reactive oxygen species and impaired antioxidant defense mechanisms. This study evaluates the association between OS and men with PCa.

METHODS

A literature search was carried out on Medline, PubMed, and ScienceDirect databases, as well as manual searches from inception up to August 2015 using the keywords "Oxidative stress" or "Reactive oxygen species" or "Lipid peroxidation" AND "Prostate cancer." All studies including data on the measurement of OS biomarkers in PCa were included.

RESULTS

Twenty-three case control studies were retrieved with sample sizes ranging from 15 to 3,613 (6,439 participants in total). Markers of OS were significantly higher in patients with PCa compared with control groups in 21 studies. Two self-controlled case studies comparing OS between PCa cells and non-PCa cells in tissue biopsies found OS to be statistically higher in PCa cancer cells. Results on markers of antioxidant capacity (superoxide dismutase, catalase, glutathione, glutathione reductase, glutathione peroxidase, uric acid, lutein, lycopene, beta carotein, vitamin A, vitamin C, vitamin E, and total antioxidants) were not completely consistent in their association with PCa.

CONCLUSIONS

Upregulated OS profiles and impairment of antioxidant defense systems may play a role in men with PCa. To confirm these findings, robust clinical trials utilizing a personalized approach which monitors both OS and antioxidant markers during therapy are warranted.

Relation between gastric cancer and protein oxidation, DNA damage, and lipid peroxidation

OBJECTS

The aim of this study is to evaluate protein oxidation, DNA damage, and lipid peroxidation in patients with gastric cancer and to investigate the relationship between oxidative stress and gastric cancer.

METHODS

We investigated changes in serum protein carbonyl (PC), advanced oxidation protein products (AOPP), and 3-nitrotyrosine (3-NT) levels, as indicators of protein oxidation, serum 8-hydroxydeoxyguanosine (8-OHdG), as a biomarker of DNA damage, and malondialdehyde (MDA), conjugated diene (CD), 4-hydroxynonenal (4-HNE), and 8-ISO-prostaglandin F2α (8-PGF) in serum, as lipid peroxidation markers in gastric cancer (GC) patients and healthy control.

RESULTS

Compared with control, a statistically significant higher values of 8-OHdG, PC, AOPP, and 3-NT were observed in the GC patients (P < 0.05). The products of lipid peroxidation, MDA, CD, 4-HNE, and 8-PGF, were significantly lower in the GC patients compared to those of control (P < 0.05). In addition, the products of oxidative stress were similar between the Helicobacter pylori positive and the negative subgroups of GC patients.

CONCLUSIONS

GC patients were characterized by increased protein oxidation and DNA damage, and decreased lipid peroxidation. Assessment of oxidative stress and augmentation of the antioxidant defense system may be important for the treatment and prevention of gastric carcinogenesis.

Oxidative stress in prostate cancer: changing research concepts towards a novel paradigm for prevention and therapeutics

A mounting body of evidence suggests that increased production of reactive oxygen species (ROS) is linked to aging processes and to the etiopathogenesis of aging-related diseases, such as cancer, diabetes, atherosclerosis and degenerative diseases like Parkinson's and Alzheimer's. Excess ROS are deleterious to normal cells, while in cancer cells, they can lead to accelerated tumorigenesis. In prostate cancer (PC), oxidative stress, an innate key event characterized by supraphysiological ROS concentrations, has been identified as one of the hallmarks of the aggressive disease phenotype. Specifically, oxidative stress is associated with PC development, progression and the response to therapy. Nevertheless, a thorough understanding of the relationships between oxidative stress, redox homeostasis and the activation of proliferation and survival pathways in healthy and malignant prostate remains elusive. Moreover, the failure of chemoprevention strategies targeting oxidative stress reduced the level of interest in the field after the recent negative results of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) trial. Therefore, a revisit of the concept is warranted and several key issues need to be addressed: The consequences of changes in ROS levels with respect to altered redox homeostasis and redox-regulated processes in PC need to be established. Similarly, the key molecular events that cause changes in the generation of ROS in PC and the role for therapeutic strategies aimed at ameliorating oxidative stress need to be identified. Moreover, the issues whether genetic/epigenetic susceptibility for oxidative stress-induced prostatic carcinogenesis is an individual phenomenon and what measurements adequately quantify prostatic oxidative stress are also crucial. Addressing these matters will provide a more rational basis to improve the design of redox-related clinical trials in PC. This review summarizes accepted concepts and principles in redox research, and explores their implications and limitations in PC.

Association of Pb, Cd, and Se concentrations and oxidative damage-related markers in different grades of prostate carcinoma

Prostate cancer is known to be affected by the heavy metal levels and oxidative damage of the body, yet there are very few studies which look into the way it occurs. The aim of this study was to determine whether blood and tissue lead (Pb), cadmium (Cd), and selenium (Se) levels are associated with oxidative damage in the context of prostate cancer progression and development. Seventy-nine patients comprising 25 patients with benign prostatic hypertrophy (BPH), 23 patients with malignant prostatic carcinoma (malign Ca), 16 patients with low-grade prostatic intraepithelial neoplasia (LGPIN), and 15 patients with high-grade prostatic intraepithelial neoplasia (HGPIN) diagnosed on the basis of their clinical profile, transrectal ultrasonography, and histopathology were included in this study. Cd and Pb levels in whole blood were found to be increased in patients with HGPIN compared with the BPH group; also, the levels of Cd in whole blood and tissue were found to be increasing in patients with malign Ca, unlike BPH patients. Moreover, the levels of malondialdehyde (MDA) in plasma and tissue were significantly increased in malign Ca, LGPIN, and HGPIN than those in BPH. However, the levels of tissue Pb were found to be decreasing in BPH, unlike the malign Ca and HGPIN patients, and the levels of tissue protein carbonyls in malign Ca were significantly lower than those in HGPIN. The levels of tissue reduced glutathione (GSH) in malign Ca were significantly lower than those in BPH. Additionally, the levels of Se in serum and tissue in LGPIN were significantly lower than those in BPH. The serum Se levels in HGPIN were also significantly lower than those in BPH and malign Ca groups. Furthermore, the concentrations of serum Se in LGPIN were significantly lower than those in malign Ca. From the Pearson correlation analysis, there were significant positive correlations between tissue Cd and MDA levels in malign Ca, LGPIN, and HGPIN and between the tissue Pb and tissue MDA and protein carbonyl levels in malign Ca. Blood Pb and tissue Pb were also significantly positively correlated with plasma MDA and protein carbonyl levels in malign Ca. In addition, blood Pb was significantly positively correlated with tissue MDA and protein carbonyl levels in malign Ca, and a significant positive correlation was also found between blood Cd and plasma protein carbonyls and tissue MDA in LGPIN. We observed that altered prooxidant-antioxidant balance and heavy metal levels may lead to an increase in oxidative damage and may consequently play an important role in prostate carcinogenesis. These findings indicate that changes in the levels of Pb, Cd, Se, MDA, protein carbonyls, and GSH in the blood and/or tissue are related to the prostatic carcinoma development and progression, although triggering one of the mentioned changes is unknown; therefore, further study is required to determine the exact steps of the process and clarify the roles of different substances in order to obtain a more detailed explanation of the phenomenon.

Mn-porphyrins as novel molecular magnetic resonance imaging contrast agents

BACKGROUND AND PURPOSE

In this study, we investigated the potential of a new class of therapeutic Mn porphyrins as molecular MRI probes for prostate cancer imaging. Two compounds of different bioavailibility were investigated: Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP(5 +)) and Mn(III) mesotetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP(5 +)). These compounds have previously been shown to have adjunctive antineoplastic activity through their actions as powerful superoxide dismutase mimics, peroxynitrite scavengers, and modulators of cellular redox-based signaling pathways. Strong paramagnetic MRI contrast properties and affinity for cancer cells suggest their potential application as novel diagnostic imaging agents.

MATERIALS AND METHODS

MRI experiments were performed at 7.0T on a Bruker Biospec horizontal bore scanner. All in-vivo experiments were performed on 12 C57 black mice implanted with RM-9 prostate cancer cells on the hind limb. Two mg/kg of MnTnHex-2-PyP(5 +) (n = 6) and 8 mg/kg MnTE-2-PyP(5 +) (n = 6) were administered intraperitoneally 90 minutes before imaging. All the images were collected using a volume coil and processed using Paravision 4.0.

RESULTS

Phantom studies reveal remarkably high T1 relaxivity changes for both metalloporphyrins, which are twofold to threefold higher than commercially available gadolinium chelates. Observable detection limits using conventional T1-weighted MRI are in the low micromolar range for both compounds. In vivo, MR relaxation changes in prostate tumor xenografts were readily observed after a single injection of either MnTE-2-PyP(5 +) or MnTnHex-2-PyP(5 +), with tumor contrast to background ratio greatest after MnTE-2-PyP(5 +) administration.

CONCLUSION

After a single dose of MnTE-2-PyP(5 +), contrast changes in prostate tumors are up to sixfold greater than in surrounding, noncancerous tissues, suggesting the potential use of this metalloporphyrin as a novel diagnostic probe for detecting prostate malignancy using MRI.

What can surrogate tissues tell us about the oxidative stress status of the prostate? A hypothesis-generating in-vivo study

BACKGROUND

Prostatic oxidative stress (OS) is androgen-regulated and a key event in the development of prostate cancer (PC). Thus, reducing prostatic OS is an attractive target for PC prevention strategies. We sought to determine if the individual's prostatic OS status can be determined by examining the OS in surrogate androgen regulated tissues from the same host.

METHODOLOGY/PRINCIPAL FINDINGS

Adult male rats were divided equally into three groups: (A-) underwent bilateral orchiectomy, (A+) received continuous testosterone supplementation or (C) were eugonadal. Serum testosterone, 8-hydroxy-2-deoxyguanosine (8-OHdG) and anti-oxidative capacity (AOC) were determined after 72 hrs and the prostate, salivary glands and the hair follicles' Dermal Papillary Cells (DPC) from each animal were harvested, embedded into tissue microarray and examined for the expression of 8-OHdG by immuno-staining. Multi-variate regression was used to analyze inter-individual differences in OS staining within each androgen group and if there was a correlation between serum testosterone, 8-OHdG or AOC and Prostatic OS in tissues of same host. At the group level, 8-OHdG staining intensity directly correlated with serum testosterone levels in all three target tissues (p>0.01, Mann-Whitney Test). Although different levels of prostatic OS were noted between rats with similar serum testosterone levels and similar systemic OS measurements (p<0.01), there were no intra-individual differences between the OS status of the prostate and DPC (p<0.05).

CONCLUSIONS/SIGNIFICANCE

The level of prostatic OS is correlated with the OS of hair follicles and salivary glands, but not systemic OS. Moreover, systemic AOC negatively correlates with both prostatic and hair follicle OS. This suggests that hair follicle and salivary gland OS can serve as surrogate markers for the efficiency of OS reduction. This has tremendous potential for the rational evaluation of patient response to prevention strategies.