Impaired antioxidant enzyme functions with increased lipid peroxidation in epithelial ovarian cancer

Lipid peroxidation: Reactive carbonyl species, protein/DNA adducts, and signaling switches in oxidative stress and cancer

Under the exposure of lipids to reactive oxygen species (ROS), lipid peroxidation proceeds non-enzymatically and generates an extremely heterogeneous mixture of reactive carbonyl species (RCS). Among them, HNE, HHE, MDA, methylglyoxal, glyoxal, and acrolein are the most studied and/or abundant ones. Over the last decades, significant progress has been achieved in understanding mechanisms of RCS generation, protein/DNA adduct formation, and their identification and quantification in biological samples. In our review, we critically discuss the advancements in understanding the roles of RCS-induced protein/DNA modifications in signaling switches to provide adaptive cell response under physiological and oxidative stress conditions. At non-toxic concentrations, RCS modify susceptible Cys residue in c-Src to activate MAPK signaling and Cys, Lys, and His residues in PTEN to cause its reversible inactivation, thereby stimulating PI3K/PKB(Akt) pathway. RCS toxic concentrations cause irreversible Cys modifications in Keap1 and IKKβ followed by stabilization of Nrf2 and activation of NF-κB, respectively, for their nuclear translocation and antioxidant gene expression. Dysregulation of these mechanisms causes diseases including cancer. Alterations in RCS, RCS detoxifying enzymes, RCS-modified protein/DNA adducts, and signaling pathways have been implicated in various cancer types.

The Role of Selenium and Manganese in the Formation, Diagnosis and Treatment of Cervical, Endometrial and Ovarian Cancer

Selenium (Se) and manganese (Mn) are essential micronutrients that are important elements of cell metabolism. They are involved in the composition of enzyme systems and regulate enzyme activity. Disturbances in the homeostasis of these micronutrients affect the development of many diseases and carcinogenesis, which can be linked to increased levels of oxidative stress and impaired antioxidant properties of many enzymes. Selenium has a very important function in maintaining immune-endocrine, metabolic and cellular homeostasis. Manganese, on the other hand, is important in development, digestion, reproduction, antioxidant defense, energy production, immune response and regulation of neuronal activity. We review the role of selenium and manganese and their effects on tumor growth, metastasis potential and remodeling of the microenvironment. We also describe their role as potential biomarkers in the diagnosis and the potential for the use of Se- and Mn-containing compounds in composition for the treatment of cancer of the reproductive organs.

Prostanoid Signaling in Cancers: Expression and Regulation Patterns of Enzymes and Receptors

Cancer-associated disturbance of prostanoid signaling provides an aberrant accumulation of prostanoids. This signaling consists of 19 target genes, encoding metabolic enzymes and G-protein-coupled receptors, and prostanoids (prostacyclin, thromboxane, and prostaglandins E2, F2α, D2, H2). The study addresses the systems biology analysis of target genes in 24 solid tumors using a data mining pipeline. We analyzed differential expression patterns of genes and proteins, promoter methylation status as well as tissue-specific master regulators and microRNAs. Tumor types were clustered into several groups according to gene expression patterns. Target genes were characterized as low mutated in tumors, with the exception of melanoma. We found at least six ubiquitin ligases and eight protein kinases that post-translationally modified the most connected proteins PTGES3 and PTGIS. Models of regulation of PTGIS and PTGIR gene expression in lung and uterine cancers were suggested. For the first time, we found associations between the patient’s overall survival rates with nine multigene transcriptomics signatures in eight tumors. Expression patterns of each of the six target genes have predictive value with respect to cytostatic therapy response. One of the consequences of the study is an assumption of prostanoid-dependent (or independent) tumor phenotypes. Thus, pharmacologic targeting the prostanoid signaling could be a probable additional anticancer strategy.

Significance of glutathione peroxidase 4 and intracellular iron level in ovarian cancer cells-"utilization" of ferroptosis mechanism

OBJECTIVE AND DESIGN

Ovarian cancer is the major cause of death in gynecologic diseases worldwide. Ferroptosis, a nonapoptotic form of cell death, is featured by accumulation of iron-based lipid peroxidation. The elevated iron level and malondialdehyde (MDA) in ovarian cancer cells suggest more vulnerable to ferroptosis, nevertheless, ferroptosis is not observed in ovarian cancer cells. Glutathione peroxidase 4 (GPX4) is a critical regulator of ferroptosis.

METHODS

We determined whether GPX4 knockdown could induce ferroptosis to prevent cell proliferation in ovarian cancer. Human ovarian cancer cells and normal human ovarian epithelial cell line IOSE-80 were cultured and administrated with deferoxamine (DFO) or ferric ammonium citrate (FAC). GPX4 knockdown was established for investigating the functions of GPX4 in ovarian cancer cells and in tumor xenograft mice.

RESULTS

A positively correlation was showed among the levels of GPX4, iron and cell proliferation. Chelation of intracellular iron by DFO disrupted intracellular iron level and was detrimental to ovarian cancer cell survival. FAC-induced elevation of intracellular iron inhibited proliferation, aggravated apoptosis, boosted inflammation and suppressed lipid peroxide reducibility in ovarian cancer cells. Knockdown of GPX4 had similar effects with FAC in ovarian cancer cells. Inhibition of GPX4 suppressed tumor growth, induced ferroptosis, accelerated cell apoptosis, reduced Fe3+ accumulation and suppressed lipid peroxide reducibility in tumor bearing mice.

CONCLUSION

We demonstrate the significance of GPX4 and intracellular iron level in ovarian cancer cells. Importantly, inhibition of GPX4 interferes with both intracellular iron homeostasis and lipid peroxide reducibility, inducing ferroptosis and exerting anti-cancer effect, which can be a potential effective strategy for ovarian cancer therapy.

Therapeutic Influence on Important Targets Associated with Chronic Inflammation and Oxidative Stress in Cancer Treatment

Chronic inflammation and oxidative stress are the interconnected pathological processes, which lead to cancer initiation and progression. The growing level of oxidative and inflammatory damage was shown to increase cancer severity and contribute to tumor spread. The overproduction of reactive oxygen species (ROS), which is associated with the reduced capacity of the endogenous cell defense mechanisms and/or metabolic imbalance, is the main contributor to oxidative stress. An abnormal level of ROS was defined as a predisposing factor for the cell transformation that could trigger pro-oncogenic signaling pathways, induce changes in gene expression, and facilitate accumulation of mutations, DNA damage, and genomic instability. Additionally, the activation of transcription factors caused by a prolonged oxidative stress, including NF-κB, p53, HIF1α, etc., leads to the expression of several genes responsible for inflammation. The resulting hyperactivation of inflammatory mediators, including TNFα, TGF-β, interleukins, and prostaglandins can contribute to the development of neoplasia. Pro-inflammatory cytokines were shown to trigger adaptive reactions and the acquisition of resistance by tumor cells to apoptosis, while promoting proliferation, invasion, and angiogenesis. Moreover, the chronic inflammatory response leads to the excessive production of free radicals, which further aggravate the initiated reactions. This review summarizes the recent data and progress in the discovery of mechanisms that associate oxidative stress and chronic inflammation with cancer onset and metastasis. In addition, the review provides insights for the development of therapeutic approaches and the discovery of natural substances that will be able to simultaneously inhibit several key oncological and inflammation-related targets.

Ovarian tissue damage after grafting: systematic review of strategies to improve follicle outcomes

Frozen-thawed human ovarian tissue endures large-scale follicle loss in the early post-grafting period, characterized by hypoxia lasting around 7 days. Tissue revascularization occurs progressively through new vessel invasion from the host and neoangiogenesis from the graft. Such reoxygenation kinetics lead to further potential damage caused by oxidative stress. The aim of the present manuscript is to provide a systematic review of proangiogenic growth factors, hormones and various antioxidants administered in the event of ovarian tissue transplantation to protect the follicle pool from depletion by boosting revascularization or decreasing oxidative stress. Although almost all investigated studies revealed an advantage in terms of revascularization and reduction in oxidative stress, far fewer demonstrated a positive impact on follicle survival. As the cascade of events driven by ischaemia after transplantation is a complex process involving numerous players, it appears that acting on specific molecular mechanisms, such as concentrations of proangiogenic growth factors, is not enough to significantly mitigate tissue damage. Strategies exploiting the activated tissue response to ischaemia for tissue healing and remodelling purposes, such as the use of antiapoptotic drugs and adult stem cells, are also discussed in the present review, since they yielded promising results in terms of follicle pool protection.

Are antioxidant enzymes essential markers in the diagnosis and monitoring of cancer patients - A review

Reactive oxygen species (ROS) play a significant role in human cells. Excessive ROS production damages important macromolecules such as nucleic acids and can initiate and develop the carcinogenesis process. Antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and xanthine oxidoreductase (XOR) are responsible for maintaining the balance between the functions of free radical formation and eliminating their excessive amounts. Based on the analyzed literature, the following conclusions can be made: 1. Antioxidant enzymes activity are important for diagnosing neoplastic diseases such as non-small-cell lung cancer, bladder cancer, ovarian cancer, and colon cancer. 2. Non-small-cell lung cancer is usually characterized by decreased SOD and CAT activity and increased glutathione GST activity. Lowered SOD, CAT, and GPx activity is characteristic of bladder cancer. XOR, CAT, SOD and GPx expression is decreased in patients with ovarian cancer. Colorectal cancer is characterized by increased MnSOD expression (in vitro studies) and SOD expression while CAT, GPx, and GR are decreased (in vivo study). 3. SOD, CAT, and XOR are promising prognostic markers in cancer of the lung, bladder, ovarian, and colon.

The Effect of Sleeve Gastrectomy on Oxidative Stress in Obesity

High concentrations of free radicals are present in the blood of obese patients. Free radicals are associated with endothelial dysfunction, diabetes, and neoplastic transformation, all conditions that are closely related to obesity. The purpose of our study was to determine whether bariatric surgery modifies the production of free radicals in obese patients. In total, 20 patients with morbid obesity, who were candidates for laparoscopic sleeve gastrectomy (SG), and 18 controls were enrolled in the study. Oxidative stress was studied in obese subjects before and after sleeve gastrectomy. The evaluation of oxidative stress was carried out on blood samples using electron paramagnetic resonance, a refined spectroscopic technique used to identify and quantify the major free radicals, such as ^•OH, O₂^•, ONOO^-, and NO. Oxidative stress was higher in subjects with morbid obesity prior to surgery, compared to the controls (CP• 9.9 ± 0.3 µM vs. 5.8 ± 0.2 µM). After SG, values decreased to levels comparable to those of controls (CP• 5.4 ± 0.2 µM). Further analysis identified O₂^• as the main free radical responsible for the oxidative stress. Obesity is associated with an increased blood concentration of free radicals. The normalization of free radicals after sleeve gastrectomy highlights another important benefit of this bariatric surgery technique.

Evaluation of trace elements associated with antioxidant enzymes in blood of primary epithelial ovarian cancer patients

Epithelial ovarian cancer (EOC) has been associated with oxidative stress (OS) due to epithelial inflammation which makes ovaries more vulnerable to the deleterious effects of reactive oxygen species (ROS). However, antioxidant enzymes (AOEs) such as manganese-superoxide dismutase (Mn-SOD), copper,zinc-superoxide dismutase (Cu,Zn-SOD) and glutathione peroxidase (GPx1) protect cells against the biological damage of ROS-induced OS and support cancer prevention by maintaining normal cell cycle progression, inhibiting proliferation, tumor invasion, angiogenesis, inflammation or inducing apoptosis. In the present study, we aimed to measure the levels of trace elements [manganese (Mn), copper (Cu), zinc (Zn) and selenium (Se)] which are structurally and/or functionally associated with the AOEs by inductively coupled plasma/mass-spectrometry (ICP/MS) in blood samples of patients with EOC (M, n = 26) and compare the data with healthy subjects (C, n = 46). Serous EOC (M1, n = 18) data were also evaluated according to the tumor grading [well or moderately well differentiated (G 1-2) vs. poorly differentiated or undifferentiated (G3)] and staging of disease [stage I-II (SI-II) vs. stage III (SIII)]. We obtained; i) The Mn and Se levels of M were significantly lower than C, ii) only Mn levels were changed [(G3_(Mn) < G 1-2 _(Mn)] in M1, iii) significant correlations were observed between [Cu and Zn levels (r = 0.701, p = 0.036) in G 1-2 and (r = 0.686, p = 0.041) in G3; Cu and Se levels (r = 0.960, p = 0.000) in G3; Mn levels and Mn-SOD expression (r = 0.551, p = 0.006) in M, (r = 0.857, p = 0.007) in G 1-2 and (r = 0.690, p = 0.056) in G3; Se levels and erythrocyte GPx1 activity (r = 0.660, p = 0.053) in G 1-2 ; Se levels and erythrocyte Cu,Zn-SOD activity (r = 0.693, p = 0.038) in G3]. The study revealed that trace elements, particularly low Mn and Se levels along with high Cu/Se ratios might be of value in all histologic subtypes of EOC. Although Mn level was important in terms of discriminating tumor grades, positive correlation between Cu-Se levels was also remarkable in patients with G 1-2 tumors of M1. Moreover, high erythrocyte Cu/Se ratios might be a favourable marker for EOC.

Assessment of oxidant-antioxidant status alterations with tumor biomarkers and reproductive system hormones in uterine MYOMAS

OBJECTIVES

Uterine myomas (UM) are responsible for significant morbidity and have adverse effects on quality of life in women. Reactive oxygen species (ROS) and antioxidant enzymes (AOE), as well as sex steroids play important roles in the reproductive physiology processes. Thus, we aimed to investigate the role of oxidant-antioxidant status in UM by measuring the AOE activities and lipid peroxidation (LPO) levels. This is the first study assessing these parameters together in UM based on also menopausal status and evaluating possible correlations between AOE activities, LPO markers, tumor biomarkers, female reproductive system hormone levels, comprehensively.

STUDY DESIGN

The study group consisted of patients who have undergone surgical resection with confirmed pathology of uterine myoma (UM, n = 25) and divided into subgroups; premenopausal (UM_pre) and postmenopausal (UM_post). Erythrocyte copper-zinc superoxide dismutase (Cu,Zn-SOD), catalase (CAT), glutathione peroxidase (GPx1) activities were measured along with plasma malondialdehyde (MDA) and urinary 8-epi-prostaglandin F2α (8-epi-PGF2α) levels in patients with UM. The obtained data were compared to the data of healthy individuals (C, n = 25) and its subgroups; premenopausal (C_pre) and postmenopausal (C_post).

RESULTS

All AOE activities were higher (∼40% for Cu,Zn-SOD, p = 0.003; ∼55% for CAT, p = 0.001; ∼15% for GPx1, p = 0.169) and the LPO levels were lower (∼60% for MDA, p = 0.011 and ∼45% for 8-epi-PGF2α, p = 0.055) in patients with UM vs control. Approximately similar alterations were observed in UM_pre vs C_pre and in UM_post vs C_post. A significant negative correlation between erythrocyte Cu,Zn-SOD activity and plasma MDA levels (r = -0.431, p = 0.005) was reported.

CONCLUSION

Decreased LPO levels might be the consequence of compensator high antioxidant enzyme activities against mild oxidative stress in the circulation of patients with UM. The marked negative correlation between erythrocyte Cu,Zn-SOD activity and plasma MDA levels also supported this finding.