Association Between Oxidative Stress and Melanoma Progression

Nutrition and melanoma: the contribution of trace elements in onset, progression, and treatment of melanoma

Melanoma is a highly malignant and drug-resistant disease that imposes a substantial economic burden on the world. There are many studies linking trace elements to diverse types of cancers, including melanoma. This review elucidates the relationship between trace elements exposure and melanoma. It was identified that copper, manganese, selenium, zinc, iron, and many other trace elements were associated with melanoma in humans. In terms of epidemiology, different elements have different correlations with melanoma. These trace elements affect the occurrence and development of melanoma through various mechanisms, such as oxidative stress and the MAPK pathway. The literature on the role of trace elements in the pathogenesis and treatment of melanoma depicts promising prospects for this field.

Programmable Release of Chemotherapeutics from Ferrocene-Based Injectable Hydrogels Slows Melanoma Growth

Hydrogel-based injectable drug delivery systems provide temporally and spatially controlled drug release with reduced adverse effects on healthy tissues. Therefore, they represent a promising therapeutic option for unresectable solid tumor entities. In this study, a peptide-starPEG/hyaluronic acid-based physical hydrogel is modified with ferrocene to provide a programmable drug release orchestrated by matrix-drug interaction and local reactive oxygen species (ROS). The injectable ROS-responsive hydrogel (hiROSponse) exhibits adequate biocompatibility and biodegradability, which are important for clinical applications. HiROSponse is loaded with the two cytostatic drugs (hiROSponsedox/ptx) doxorubicin (dox) and paclitaxel (ptx). Dox is a hydrophilic compound and its release is mainly controlled by Fickian diffusion, while the hydrophobic interactions between ptx and ferrocene can control its release and thus be regulated by the oxidation of ferrocene to the more hydrophilic state of ferrocenium. In a syngeneic malignant melanoma-bearing mouse model, hiROSponsedox/ptx slows tumor growth without causing adverse side effects and doubles the relative survival probability. Programmable release is further demonstrated in a tumor model with a low physiological ROS level, where dox release, low dose local irradiation, and the resulting ROS-triggered ptx release lead to tumor growth inhibition and increased survival.

Melatonin/Sericin Wound Healing Patches: Implications for Melanoma Therapy

Melatonin and sericin exhibit antioxidant properties and may be useful in topical wound healing patches by maintaining redox balance, cell integrity, and regulating the inflammatory response. In human skin, melatonin suppresses damage caused by ultraviolet radiation (UVR) which involves numerous mechanisms associated with reactive oxygen species/reactive nitrogen species (ROS/RNS) generation and enhancing apoptosis. Sericin is a protein mainly composed of glycine, serine, aspartic acid, and threonine amino acids removed from the silkworm cocoon (particularly Bombyx mori and other species). It is of interest because of its biodegradability, anti-oxidative, and anti-bacterial properties. Sericin inhibits tyrosinase activity and promotes cell proliferation that can be supportive and useful in melanoma treatment. In recent years, wound healing patches containing sericin and melatonin individually have attracted significant attention by the scientific community. In this review, we summarize the state of innovation of such patches during 2021-2023. To date, melatonin/sericin-polymer patches for application in post-operational wound healing treatment has been only sparingly investigated and it is an imperative to consider these materials as a promising approach targeting for skin tissue engineering or regenerative dermatology.

Vitamin D in Melanoma: Potential Role of Cytochrome P450 Enzymes

Vitamin D is a promising anticancer agent for the prevention and treatment of several cancers, including melanoma. Low 25-hydroxyvitamin D levels, a routinely used marker for vitamin D, have been suggested as one of the factors in the development and progression of melanoma. The parent vitamin D needs activation by cytochrome P450 (CYP) enzymes to exert its actions via the vitamin D receptor (VDR). This review discusses the role of vitamin D in melanoma and how CYP-mediated metabolism can potentially affect the actions of vitamin D. Through interacting with the retinoid X receptor, VDR signaling leads to anti-inflammatory, antioxidative, and anticancer actions. Calcitriol, the dihydroxylated form of vitamin D3, is the most active and potent ligand of VDR. CYP27A1, CYP27B1, and CYP2R1 are involved in the activation of vitamin D, whereas CYP24A1 and CYP3A4 are responsible for the degradation of the active vitamin D. CYP24A1, the primary catabolic enzyme of calcitriol, is overexpressed in melanoma tissues and cells. Several drug classes and natural health products can modulate vitamin D-related CYP enzymes and eventually cause lower levels of vitamin D and its active metabolites in tissues. Although the role of vitamin D in the development of melanoma is yet to be fully elucidated, it has been proposed that melanoma prevention may be significantly aided by increased vitamin D signaling. Furthermore, selective targeting of the catabolic enzymes responsible for vitamin D degradation could be a plausible strategy in melanoma therapy. Vitamin D signaling can be improved by utilizing dietary supplements or by modulating CYP metabolism. A positive association exists between the intake of vitamin D supplements and improved prognosis for melanoma patients. Further investigation is required to determine the function of vitamin D supplementation and specific enzyme targeting in the prevention of melanoma.

Protective Effect of Fermented Sea Tangle Extract on Skin Cell Damage Caused by Particulate Matter

The skin is directly exposed to atmospheric pollutants, especially particulate matter 2.5 (PM2.5) in the air, which poses significant harm to skin health. However, limited research has been performed to identify molecules that can confer resistance to such substances. Herein, we analyzed the effect of fermented sea tangle (FST) extract on PM2.5-induced human HaCaT keratinocyte damage. Results showed that FST extract, at concentrations less than 800 μg/mL, exhibited non-significant toxicity to cells and concentration-dependent inhibition of PM2.5-induced reactive oxygen species (ROS) production. PM2.5 induced oxidative stress by stimulating ROS, resulting in DNA damage, lipid peroxidation, and protein carbonylation, which were inhibited by the FST extract. FST extract significantly suppressed the increase in calcium level and apoptosis caused by PM2.5 treatment and significantly restored the reduced cell viability. Mitochondrial membrane depolarization occurred due to PM2.5 treatment, however, FST extract recovered mitochondrial membrane polarization. PM2.5 inhibited the expression of the anti-apoptotic protein Bcl-2, and induced the expression of pro-apoptotic proteins Bax and Bim, the apoptosis initiator caspase-9, as well as the executor caspase-3, however, FST extract effectively protected the changes in the levels of these proteins caused by PM2.5. Interestingly, pan-caspase inhibitor Z-VAD-FMK treatment enhanced the anti-apoptotic effect of FST extract in PM2.5-treated cells. Our results indicate that FST extract prevents PM2.5-induced cell damage via inhibition of mitochondria-mediated apoptosis in human keratinocytes. Accordingly, FST extract could be included in skin care products to protect cells against the harmful effects of PM2.5.

The potential role of reprogrammed glucose metabolism: an emerging actionable codependent target in thyroid cancer

Although the incidence of thyroid cancer is increasing year by year, most patients, especially those with differentiated thyroid cancer, can usually be cured with surgery, radioactive iodine, and thyroid-stimulating hormone suppression. However, treatment options for patients with poorly differentiated thyroid cancers or radioiodine-refractory thyroid cancer have historically been limited. Altered energy metabolism is one of the hallmarks of cancer and a well-documented feature in thyroid cancer. In a hypoxic environment with extreme nutrient deficiencies resulting from uncontrolled growth, thyroid cancer cells utilize "metabolic reprogramming" to satisfy their energy demand and support malignant behaviors such as metastasis. This review summarizes past and recent advances in our understanding of the reprogramming of glucose metabolism in thyroid cancer cells, which we expect will yield new therapeutic approaches for patients with special pathological types of thyroid cancer by targeting reprogrammed glucose metabolism.

Oxidative Stress in Melanoma: Beneficial Antioxidant and Pro-Oxidant Therapeutic Strategies

Cutaneous melanoma ranks as the fifth most common cancer in the United States and represents one of the deadliest forms of skin cancer. While recent advances in systemic targeted therapies and immunotherapies have positively impacted melanoma survival, the survival rate of stage IV melanoma remains at a meager 32%. Unfortunately, tumor resistance can impede the effectiveness of these treatments. Oxidative stress is a pivotal player in all stages of melanoma progression, with a somewhat paradoxical function that promotes tumor initiation but hinders vertical growth and metastasis in later disease. As melanoma progresses, it employs adaptive mechanisms to lessen oxidative stress in the tumor environment. Redox metabolic rewiring has been implicated in acquired resistance to BRAF/MEK inhibitors. A promising approach to enhance the response to therapy involves boosting intracellular ROS production using active biomolecules or targeting enzymes that regulate oxidative stress. The complex interplay between oxidative stress, redox homeostasis, and melanomagenesis can also be leveraged in a preventive context. The purpose of this review is to provide an overview of oxidative stress in melanoma, and how the antioxidant system may be manipulated in a therapeutic context for improved efficacy and survival.

Reactive Oxygen Species and Long Non-Coding RNAs, an Unexpected Crossroad in Cancer Cells

Long non-coding RNAs (lncRNA) have recently been identified as key regulators of oxidative stress in several malignancies. The level of reactive oxygen species (ROS) must be constantly regulated to maintain cancer cell proliferation and chemoresistance and to prevent apoptosis. This review will discuss how lncRNAs alter the ROS level in cancer cells. We will first describe the role of lncRNAs in the nuclear factor like 2 (Nrf-2) coordinated antioxidant response of cancer cells. Secondly, we show how lncRNAs can promote the Warburg effect in cancer cells, thus shifting the cancer cell’s “building blocks” towards molecules important in oxidative stress regulation. Lastly, we explain the role that lncRNAs play in ROS-induced cancer cell apoptosis and proliferation.

Role of Reactive Oxygen Species in Aging and Age-Related Diseases: A Review

Research on the role of reactive oxygen species (ROS) in the aging process has advanced significantly over the last two decades. In light of recent findings, ROS takes part in the aging process of cells along with contributing to various physiological signaling pathways. Antioxidants being cells' natural defense mechanism against ROS-mediated alteration, play an imperative role to maintain intracellular ROS homeostasis. Although the complete understanding of the ROS regulated aging process is yet to be fully comprehended, current insights into various sources of cellular ROS and their correlation with the aging process and age-related diseases are portrayed in this review. In addition, results on the effect of antioxidants on ROS homeostasis and the aging process as well as their advances in clinical trials are also discussed in detail. The future perspective in ROS-antioxidant dynamics on antiaging research is also marshaled to provide future directions for ROS-mediated antiaging research fields.

Inflammatory landscape in Xeroderma pigmentosum patients with cutaneous melanoma

Xeroderma pigmentosum (XP) is a DNA repair disease that predisposes to early skin cancers as cutaneous melanoma. Melanoma microenvironment contains inflammatory mediators, which would be interesting biomarkers for the prognosis or for the identification of novel therapeutic targets. We used a PCR array to evaluate the transcriptional pattern of 84 inflammatory genes in melanoma tumors obtained from XP patients (XP-Mel) and in sporadic melanoma (SP-Mel) compared to healthy skin. Commonly expressed inflammatory genes were further explored via GTEx and GEPIA databases. The differentially expressed inflammatory genes in XP were compared to their expression in skin exposed to UVs, and evaluated on the basis of the overall survival outcomes of patients with melanoma. Monocyte subsets of patients with SP-Mel, XP and healthy donors were also assessed. PCR array data revealed that 34 inflammatory genes were under-expressed in XP-Mel compared to SP-Mel. Differentially expressed genes that were common in XP-Mel and SP-Mel were correlated with the transcriptomic datasets from GEPIA and GTEx and highlighted the implication of KLK1 and IL8 in the tumorigenesis. We showed also that in XP-Mel tumors, there was an overexpression of KLK6 and KLK10 genes, which seems to be associated with a bad survival rate. As for the innate immunity, we observed a decrease of intermediate monocytes in patients with SP-Mel and in XP. We highlight an alteration in the immune response in XP patients. We identified candidate biomarkers involved in the tumorigenesis, and in the survival of patients with melanoma. Intermediate monocyte's in patients at risk could be a prognostic biomarker for melanoma outcome.

NRF2 and Key Transcriptional Targets in Melanoma Redox Manipulation

Melanocytes are dendritic, pigment-producing cells located in the skin and are responsible for its protection against the deleterious effects of solar ultraviolet radiation (UVR), which include DNA damage and elevated reactive oxygen species (ROS). They do so by synthesizing photoprotective melanin pigments and distributing them to adjacent skin cells (e.g., keratinocytes). However, melanocytes encounter a large burden of oxidative stress during this process, due to both exogenous and endogenous sources. Therefore, melanocytes employ numerous antioxidant defenses to protect themselves; these are largely regulated by the master stress response transcription factor, nuclear factor erythroid 2-related factor 2 (NRF2). Key effector transcriptional targets of NRF2 include the components of the glutathione and thioredoxin antioxidant systems. Despite these defenses, melanocyte DNA often is subject to mutations that result in the dysregulation of the proliferative mitogen-activated protein kinase (MAPK) pathway and the cell cycle. Following tumor initiation, endogenous antioxidant systems are co-opted, a consequence of elevated oxidative stress caused by metabolic reprogramming, to establish an altered redox homeostasis. This altered redox homeostasis contributes to tumor progression and metastasis, while also complicating the application of exogenous antioxidant treatments. Further understanding of melanocyte redox homeostasis, in the presence or absence of disease, would contribute to the development of novel therapies to aid in the prevention and treatment of melanomas and other skin diseases.

Continuous ZnO nanoparticle exposure induces melanoma-like skin lesions in epidermal barrier dysfunction model mice through anti-apoptotic effects mediated by the oxidative stress–activated NF-κB pathway

Background

Increasing interest in the hazardous properties of zinc oxide nanoparticles (ZnO NPs), commonly used as ultraviolet filters in sunscreen, has driven efforts to study the percutaneous application of ZnO NPs to diseased skin; however, in-depth studies of toxic effects on melanocytes under conditions of epidermal barrier dysfunction remain lacking.

Methods

Epidermal barrier dysfunction model mice were continuously exposed to a ZnO NP-containing suspension for 14 and 49 consecutive days in vivo. Melanoma-like change and molecular mechanisms were also verified in human epidermal melanocytes treated with 5.0 µg/ml ZnO NPs for 72 h in vitro.

Results

ZnO NP application for 14 and 49 consecutive days induced melanoma-like skin lesions, supported by pigmented appearance, markedly increased number of melanocytes in the epidermis and dermis, increased cells with irregular nuclei in the epidermis, recruited dendritic cells in the dermis and dysregulated expression of melanoma-associated gene Fkbp51, Trim63 and Tsp 1. ZnO NPs increased oxidative injury, inhibited apoptosis, and increased nuclear factor kappa B (NF-κB) p65 and Bcl-2 expression in melanocytes of skin with epidermal barrier dysfunction after continuously treated for 14 and 49 days. Exposure to 5.0 µg/ml ZnO NPs for 72 h increased cell viability, decreased apoptosis, and increased Fkbp51 expression in melanocytes, consistent with histological observations in vivo. The oxidative stress–mediated mechanism underlying the induction of anti-apoptotic effects was verified using the reactive oxygen species scavenger N-acetylcysteine.

Conclusions

The entry of ZnO NPs into the stratum basale of skin with epidermal barrier dysfunction resulted in melanoma-like skin lesions and an anti-apoptotic effect induced by oxidative stress, activating the NF-κB pathway in melanocytes.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01308-w.

Redox-Related Proteins in Melanoma Progression

Melanoma is the most aggressive type of skin cancer. Despite the available therapies, the minimum residual disease is still refractory. Reactive oxygen and nitrogen species (ROS and RNS) play a dual role in melanoma, where redox imbalance is involved from initiation to metastasis and resistance. Redox proteins modulate the disease by controlling ROS/RNS levels in immune response, proliferation, invasion, and relapse. Chemotherapeutics such as BRAF and MEK inhibitors promote oxidative stress, but high ROS/RNS amounts with a robust antioxidant system allow cells to be adaptive and cooperate to non-toxic levels. These proteins could act as biomarkers and possible targets. By understanding the complex mechanisms involved in adaptation and searching for new targets to make cells more susceptible to treatment, the disease might be overcome. Therefore, exploring the role of redox-sensitive proteins and the modulation of redox homeostasis may provide clues to new therapies. This study analyzes information obtained from a public cohort of melanoma patients about the expression of redox-generating and detoxifying proteins in melanoma during the disease stages, genetic alterations, and overall patient survival status. According to our analysis, 66% of the isoforms presented differential expression on melanoma progression: NOS2, SOD1, NOX4, PRX3, PXDN and GPX1 are increased during melanoma progression, while CAT, GPX3, TXNIP, and PRX2 are decreased. Besides, the stage of the disease could influence the result as well. The levels of PRX1, PRX5 and PRX6 can be increased or decreased depending on the stage. We showed that all analyzed isoforms presented some genetic alteration on the gene, most of them (78%) for increased mRNA expression. Interestingly, 34% of all melanoma patients showed genetic alterations on TRX1, most for decreased mRNA expression. Additionally, 15% of the isoforms showed a significant reduction in overall patient survival status for an altered group (PRX3, PRX5, TR2, and GR) and the unaltered group (NOX4). Although no such specific antioxidant therapy is approved for melanoma yet, inhibitors or mimetics of these redox-sensitive proteins have achieved very promising results. We foresee that forthcoming investigations on the modulation of these proteins will bring significant advances for cancer therapy.

3, 3'- (3, 5-DCPBC) Down-Regulates Multiple Phosphokinase Dependent Signal Transduction Pathways in Malignant Melanoma Cells through Specific Diminution of EGFRY1086 Phosphorylation

Melanoma is the most dangerous skin malignancy due to its strong metastatic potential with high mortality. Activation of crucial signaling pathways enforcing melanoma progression depends on phosphorylation of distinct tyrosine kinases and oxidative stress. We here investigated the effect of a bis-coumarin derivative [3, 3′- ((3″, 5′-Dichlorophenyl) methylene) bis (4-hydroxy-2H-chromen-2-one)] [3, 3′- (3, 5-DCPBC)] on human melanoma cell survival, growth, proliferation, migration, intracellular redox state, and deciphered associated signaling pathways. This derivative is toxic for melanoma cells and non-toxic for melanocytes, their benign counterpart, and fibroblasts. 3, 3′- (3, 5-DCPBC) inhibits cell survival, migration, and proliferation of different metastatic and non-metastatic melanoma cell lines through profound suppression of the phosphorylation of Epidermal Growth Factor receptor (EGFR) and proto-oncogene cellular sarcoma (c-SRC) related downstream pathways. Thus, 3, 3′- (3, 5-DCPBC) endowed with the unique property to simultaneously suppress phosphorylation of multiple downstream kinases, such as EGFR/JAK/STAT and EGFR/SRC and their corresponding transcription factors.

Oxidative Stress-Related Mechanisms in Melanoma and in the Acquired Resistance to Targeted Therapies

Melanoma is a highly aggressive cancer with the poorest prognosis, representing the deadliest form of skin cancer. Activating mutations in BRAF are the most frequent genetic alterations, present in approximately 50% of all melanoma cases. The use of specific inhibitors towards mutant BRAF variants and MEK, a downstream signaling target of BRAF in the MAPK pathway, has significantly improved progression-free and overall survival in advanced melanoma patients carrying BRAF mutations. Nevertheless, despite these improvements, resistance still develops within the first year of therapy in around 50% of patients, which is a significant problem in managing BRAF-mutated advanced melanoma. Understanding these mechanisms is one of the mainstreams of the research on BRAFi/MEKi acquired resistance. Both genetic and epigenetic mechanisms have been described. Moreover, in recent years, oxidative stress has emerged as another major force involved in all the phases of melanoma development, from initiation to progression until the onsets of the metastatic phenotype and chemoresistance, and has thus become a target for therapy. In the present review, we discuss the current knowledge on oxidative stress and its signaling in melanoma, as well as the oxidative stress-related mechanisms in the acquired resistance to targeted therapies.

Anti-melanoma effects of concomitant inhibition of SIRT1 and SIRT3 in BrafV600E/PtenNULL mice

Novel therapeutic strategies are required for the effective and lasting treatment of metastatic melanoma, one of the deadliest skin malignancies. In this study, we determined the anti-melanoma efficacy of 4'-bromo-resveratrol (4'-BR), which is a small molecule dual inhibitor of SIRT1 and SIRT3 in a Braf^V600E/Pten^NULL mouse model that recapitulates human disease, including metastases. Tumors were induced by topical application of 4-hydroxy-tamoxifen on shaved backs of 10-week-old mice, and the effects of 4'-BR (5-30 mg/kg b.wt.; intraperitoneally; 3d/week for 5 weeks) were assessed on melanoma development and progression. We found that 4'-BR at a dose of 30 mg/kg significantly reduced size and volume of primary melanoma tumors, as well as lung metastasis, with no adverse effects. Further, mechanistic studies on tumors showed significant modulation in markers of proliferation, survival and melanoma progression. As SIRT1 and SIRT3 are linked to immunomodulation, we performed differential gene expression analysis via NanoString PanCancer Immune Profiling panel (770 genes). Our data demonstrated that 4'-BR significantly downregulated genes related to metastasis-promotion, chemokine/cytokine-regulation, and innate/adaptive immune functions. Overall, inhibition of SIRT1 and SIRT3 by 4'-BR is a promising anti-melanoma therapy with anti-metastatic and immunomodulatory activities warranting further detailed studies, including clinical investigations.

Metastatic Melanoma Progression Is Associated with Endothelial Nitric Oxide Synthase Uncoupling Induced by Loss of eNOS:BH4 Stoichiometry

Melanoma is the most aggressive type of skin cancer due to its high capability of developing metastasis and acquiring chemoresistance. Altered redox homeostasis induced by increased reactive oxygen species is associated with melanomagenesis through modulation of redox signaling pathways. Dysfunctional endothelial nitric oxide synthase (eNOS) produces superoxide anion (O2-•) and contributes to the establishment of a pro-oxidant environment in melanoma. Although decreased tetrahydrobiopterin (BH4) bioavailability is associated with eNOS uncoupling in endothelial and human melanoma cells, in the present work we show that eNOS uncoupling in metastatic melanoma cells expressing the genes from de novo biopterin synthesis pathway Gch1, Pts, and Spr, and high BH4 concentration and BH4:BH2 ratio. Western blot analysis showed increased expression of Nos3, altering the stoichiometry balance between eNOS and BH4, contributing to NOS uncoupling. Both treatment with L-sepiapterin and eNOS downregulation induced increased nitric oxide (NO) and decreased O2• levels, triggering NOS coupling and reducing cell growth and resistance to anoikis and dacarbazine chemotherapy. Moreover, restoration of eNOS activity impaired tumor growth in vivo. Finally, NOS3 expression was found to be increased in human metastatic melanoma samples compared with the primary site. eNOS dysfunction may be an important mechanism supporting metastatic melanoma growth and hence a potential target for therapy.

HSP70iQ435A to subdue autoimmunity and support anti-tumor responses

Developing immunosuppressive therapies for autoimmune diseases comes with a caveat that immunosuppression may promote the risk of developing other conditions or diseases. We have previously shown that biolistic delivery of an expression construct encoding inducible HSP70 (HSP70i) with one amino acid modification in the dendritic cell (DC) activating moiety 435-445 (HSP70iQ435A) to mouse skin resulted in significant immunosuppressive activity of autoimmune vitiligo, associated with fewer tissue infiltrating T cells. To prepare HSP70iQ435A as a potential therapeutic for autoimmune vitiligo, in this study we evaluated whether and how biolistic delivery of HSP70iQ435A in mice affects anti-tumor responses. We found that HSP70iQ435A in fact supports anti-tumor responses in melanoma-challenged C57BL/6 mice. Biolistic delivery of the HSP70iQ435A-encoding construct to mice elicited significant anti-HSP70 titers, and anti-HSP70 IgG and IgM antibodies recognize surface-expressed and cytoplasmic HSP70i in human and mouse melanoma cells. A peptide scan revealed that the anti-HSP70 antibodies recognize a specific C-terminal motif within the HSP70i protein. The antibodies elicited surface CD107A expression among mouse NK cells, representative of antibody-mediated cellular cytotoxicity (ADCC), supporting the concept, that HSP70iQ435A-encoding DNA elicits a humoral response to the stress protein expressed selectively on the surface of melanoma cells. Thus, besides limiting autoimmunity and inflammation, HSP70iQ435A elicits humoral responses that limit tumor growth and may be used in conjunction with immune checkpoint inhibitors to not only control tumor but to also limit adverse events following tumor immunotherapy.

Minocycline Impact on Redox Homeostasis of Normal Human Melanocytes HEMn-LP Exposed to UVA Radiation and Hydrogen Peroxide

Minocycline is a semisynthetic tetracycline antibiotic. In addition to its antibacterial activity, minocycline shows many non-antibiotic, beneficial effects, including antioxidative action. The property is responsible, e.g., for anti-inflammatory, neuroprotective, and cardioprotective effects of the drug. However, long-term pharmacotherapy with minocycline may lead to hyperpigmentation of the skin. The reasons for the pigmentation disorders include the deposition of the drug and its metabolites in melanin-containing cells and the stimulation of melanogenesis. The adverse drug reaction raises a question about the influence of the drug on melanocyte homeostasis. The study aimed to assess the effect of minocycline on redox balance in human normal melanocytes HEMn-LP exposed to hydrogen peroxide and UVA radiation. The obtained results indicate that minocycline induced oxidative stress in epidermal human melanocytes. The drug inhibited cell proliferation, decreased the level of reduced thiols, and stimulated the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). The described changes were accompanied by an increase in the intracellular level of ROS. On the other hand, pretreatment with minocycline at the same concentrations increased cell viability and significantly attenuated the oxidative stress in melanocytes exposed to hydrogen peroxide and UVA radiation. Moreover, the molecular docking analysis revealed that the different influence of minocycline and other tetracyclines on CAT activity can be related to the location of the binding site.

The impact of the co-exposure of melanoma cells to chlorogenic acid and a moderate-strength static magnetic field

A static magnetic field (SMF) or the bioactive compounds that are found in foods are potential agents that can be used to support cancer therapy. Therefore, the aim of our study was to assess the impact of the SMF that are induced by neodymium magnets on the culture growth and antioxidant status of melanoma cells that had been treated with chlorogenic acid (CGA). The melanoma cells, the control and those that had been treated with CGA, were put in special magnetic test chambers that generated a 0.7 T magnetic field. The mRNA levels of the antioxidant enzymes were analyzed using RT-qPCR. The activity of SOD, GPx, and CAT was measured in the cell lysates. While the expression and activity of the antioxidant enzymes was inhibited relative to the untreated cells as a result of the CGA treatment (1 mmol/L), it was not after the CGA treatment in combination with an SMF. The demonstrated cytotoxicity of CGA (1 mmol/L) and its inhibition of the antioxidant enzymes suggests the usefulness of phenolic compounds as a supporting pharmacological treatment for melanoma. PRACTICAL APPLICATIONS: Phenolic acids and their derivatives, which are the bioactive components of the human diet, are signal molecules that transfer information from the external environment that affects the level of gene expression in cells. This study suggests the usefulness of phenolic compounds as a supporting pharmacological treatment for melanoma and seems to be important for the development of experimental oncology.

Compensatory Neuroprotective Response of Thioredoxin Reductase against Oxidative-Nitrosative Stress Induced by Experimental Autoimmune Encephalomyelitis in Rats: Modulation by Theta Burst Stimulation

Cortical theta burst stimulation (TBS) structured as intermittent (iTBS) and continuous (cTBS) could prevent the progression of the experimental autoimmune encephalomyelitis (EAE). The interplay of brain antioxidant defense systems against free radicals (FRs) overproduction induced by EAE, as well as during iTBS or cTBS, have not been entirely investigated. This study aimed to examine whether oxidative-nitrogen stress (ONS) is one of the underlying pathophysiological mechanisms of EAE, which may be changed in terms of health improvement by iTBS or cTBS. Dark Agouti strain female rats were tested for the effects of EAE and TBS. The rats were randomly divided into the control group, rats specifically immunized for EAE and nonspecifically immuno-stimulated with Complete Freund's adjuvant. TBS or sham TBS was applied to EAE rats from 14th-24th post-immunization day. Superoxide dismutase activity, levels of superoxide anion (O₂^•-), lipid peroxidation, glutathione (GSH), nicotinamide adenine dinucleotide phosphate (NADPH), and thioredoxin reductase (TrxR) activity were analyzed in rat spinal cords homogenates. The severity of EAE clinical coincided with the climax of ONS. The most critical result refers to TrxR, which immensely responded against the applied stressors of the central nervous system (CNS), including immunization and TBS. We found that the compensatory neuroprotective role of TrxR upregulation is a positive feedback mechanism that reduces the harmfulness of ONS. iTBS and cTBS both modulate the biochemical environment against ONS at a distance from the area of stimulation, alleviating symptoms of EAE. The results of our study increase the understanding of FRs' interplay and the role of Trx/TrxR in ONS-associated neuroinflammatory diseases, such as EAE. Also, our results might help the development of new ideas for designing more effective medical treatment, combining neuropsychological with noninvasive neurostimulation-neuromodulation techniques to patients living with MS.

Melanoma in the liver: Oxidative stress and the mechanisms of metastatic cell survival

Metastatic melanoma is a fatal disease with a rapid systemic dissemination. The most frequent target sites are the liver, bone, and brain. Melanoma metastases represent a heterogeneous cell population, which associates with genomic instability and resistance to therapy. Interaction of melanoma cells with the hepatic sinusoidal endothelium initiates a signaling cascade involving cytokines, growth factors, bioactive lipids, and reactive oxygen and nitrogen species produced by the cancer cell, the endothelium, and also by different immune cells. Endothelial cell-derived NO and H₂O₂ and the action of immune cells cause the death of most melanoma cells that reach the hepatic microvascularization. Surviving melanoma cells attached to the endothelium of pre-capillary arterioles or sinusoids may follow two mechanisms of extravasation: a) migration through vessel fenestrae or b) intravascular proliferation followed by vessel rupture and microinflammation. Invading melanoma cells first form micrometastases within the normal lobular hepatic architecture via a mechanism regulated by cross-talk with the stroma and multiple microenvironment-related molecular signals. In this review special emphasis is placed on neuroendocrine (systemic) mechanisms as potential promoters of liver metastatic growth. Growing metastatic cells undergo functional and metabolic changes that increase their capacity to withstand oxidative/nitrosative stress, which favors their survival. This adaptive process also involves upregulation of Bcl-2-related antideath mechanisms, which seems to lead to the generation of more resistant cell subclones.

Oxidative stress and antioxidants in the pathophysiology of malignant melanoma

The high number of somatic mutations in the melanoma genome associated with cumulative ultra violet (UV) exposure has rendered it one of the most difficult of cancers to treat. With new treatment approaches based on targeted and immune therapies, drug resistance has appeared as a consistent problem. Redox biology, including reactive oxygen and nitrogen species (ROS and RNS), plays a central role in all aspects of melanoma pathophysiology, from initiation to progression and to metastatic cells. The involvement of melanin production and UV radiation in ROS/RNS generation has rendered the melanocytic lineage a unique system for studying redox biology. Overall, an elevated oxidative status has been associated with melanoma, thus much effort has been expended to prevent or treat melanoma using antioxidants which are expected to counteract oxidative stress. The consequence of this redox-rebalance seems to be two-fold: on the one hand, cells may behave less aggressively or even undergo apoptosis; on the other hand, cells may survive better after being disseminated into the circulating system or after drug treatment, thus resulting in metastasis promotion or further drug resistance. In this review we summarize the current understanding of redox signaling in melanoma at cellular and systemic levels and discuss the experimental and potential clinic use of antioxidants and new epigenetic redox modifiers.

Rosiglitazone-induced changes in the oxidative stress metabolism and fatty acid composition in relation with trace element status in the primary adipocytes

Background

Metabolic syndrome, obesity and type 2 diabetes are metabolic disorders characterized by the insulin resistance and the impairment in the insulin secretion. Since impairment in the oxidative stress and adipocyte metabolism contribute to the formation of obesity and diabetes, targeting adipose tissue can be considered as an effective approach to fight against them. Rosiglitazone is used for treatment for patients with type 2 diabetes via inducing lipogenesis and transdifferentiation of white adipose tissue into brown adipose tissue. Since the development of such therapeutics is required to control the formation and function of brown fat cells, we aimed to reveal possible molecular mechanisms behind rosiglitazone induced biochemical changes in the adipose tissue.

Methods

Cells were expanded in the adipocyte culture medium supplemented with 5 µg/mL insulin following 2 days' induction. After those cells were treated with rosiglitazone 0, 0.13 mol/L and 10 µmol/L rosiglitazone for 48 hours and at 8th day, cells were collected and stored at -80 °C. Then the cells were used to evaluate antioxidant enzyme activities, mineral and trace element levels and fatty acid composition.

Results

Glucose-6-phosphate dehydrogenase and glutathione reductase significantly reduced in rosiglitazone-treated groups compared to the control. Na, Mg, K, Ca, Cr, Fe, Ni, Cu, Zn, Rb, Sr, Cs, Ba and Pb were determined in the cell lysates via ICP-MS. Also, relative FAME content decreased in the rosiglitazone-treated groups compared to the control.

Conclusions

Rosiglitazone treatment at low doses showed promising results which may promote brown adipose tissue formation.

Thiol-disulphide Homeostasis in Essential Thrombocythemia Patients

Background

This study aimed to show the status of thioldisulphide homeostasis in essential thrombocytosis patients, which is known to play a role in platelet function.

Methods

The study included 27 ET patients and a control group of 36 healthy subjects. Serum total (-SH + -S-S-) and native (-SH) thiol levels were measured in all subjects using an automatic method.

Results

Age and gender distribution were similar in both groups. Compared with the control group, in the ET group, there were increased native thiol and total thiol levels (p = 0.001, p = 0.046). There was no correlation between thiol, total thiol and disulphide ratios with Jak2 mutation, hemorrhage and thrombosis. A positive correlation was determined between thrombosis and thiol disulphide homeostasis (p = 0.058). The study results showed that thiol-disulphide homeostasis shifted to the proliferative side in ET, in which ineffective erythropoiesis was predominant. It is also known that platelets are more active in ET cases and thiol disulphide balance is important in platelet function.

Conclusions

This result suggests that thrombotic complications may be reduced if the formation is achieved of mechanisms (oxidation mechanisms) that will trigger the increase of disulphide groups. However, more extensive research is needed on this subject.

Primary malignant melanoma of the biliary tract: A case report and literature review

BACKGROUND

Primary malignant melanoma of the biliary tract (MBT) is a rare condition whose diagnosis requires excluding a primary origin in another location. This paper reviews the most important characteristics of MBT cases published in the literature and reports a new case. The patient reported here is the first case of primary malignant melanoma of the biliary tract with pulmonary metastasis treated with immunotherapy. This patient remains disease-free 36 mo after the treatment of metastatic lung lesions.

CASE SUMMARY

A 51-year-old man was admitted to the gastrointestinal department to study obstructive jaundice of a 1 wk clinical course. Magnetic resonance cholangiopancreatography revealed dilatation of the intrahepatic biliary tract and stenosis of the common hepatic duct. Given the suspicion of biliary tract neoplasia, cholecystectomy and resection of the common hepatic duct were performed with hepatic jejunostomy free of complications. Anatomo-pathological diagnosis was melanoma. After intervention, the patient was referred to the Department of Medical Oncology, where a primary origin was excluded in the skin, mucosa, and eyes. This confirmed diagnosis of primary biliary tract melanoma. Computed tomography was performed 12 mo after the procedure revealed several subcentimetric lung nodules. Wedge resection was performed. After confirming the diagnosis of pulmonary metastasis of primary melanoma of the biliary tract, the patient was started on immunotherapy with nivolumab. Tolerance to treatment was excellent. The patient remains disease-free 36 mo after the treatment of metastatic lung lesions.

CONCLUSION

The patient reported here is the first case of primary malignant melanoma of the biliary tract with lung metastases successfully treated with immunotherapy.

Effect of Sulforaphane and 5-Aza-2'-Deoxycytidine on Melanoma Cell Growth

Background: UV exposure-induced oxidative stress is implicated as a driving mechanism for melanoma. Increased oxidative stress results in DNA damage and epigenetic dysregulation. Accordingly, we explored whether a low dose of the antioxidant sulforaphane (SFN) in combination with the epigenetic drug 5-aza-2’-deoxycytidine (DAC) could slow melanoma cell growth. SFN is a natural bioactivated product of the cruciferous family, while DAC is a DNA methyltransferase inhibitor. Methods: Melanoma cell growth characteristics, gene transcription profiles, and histone epigenetic modifications were measured after single and combination treatments with SFN and DAC. Results: We detected melanoma cell growth inhibition and specific changes in gene expression profiles upon combinational treatments with SFN and DAC, while no significant alterations in histone epigenetic modifications were observed. Dysregulated gene transcription of a key immunoregulator cytokine—C-C motif ligand 5 (CCL-5)—was validated. Conclusions: These results indicate a potential combinatorial effect of a dietary antioxidant and an FDA-approved epigenetic drug in controlling melanoma cell growth.

Approaches and Methods to Measure Oxidative Stress in Clinical Samples: Research Applications in the Cancer Field

Reactive oxygen species (ROS) are common by-products of normal aerobic cellular metabolism and play important physiological roles in intracellular cell signaling and homeostasis. The human body is equipped with antioxidant systems to regulate the levels of these free radicals and maintain proper physiological function. However, a condition known as oxidative stress (OS) occurs, when ROS overwhelm the body's ability to readily detoxify them. Excessive amounts of free radicals generated under OS conditions cause oxidative damage to proteins, lipids, and nucleic acids, severely compromising cell health and contributing to disease development, including cancer. Biomarkers of OS can therefore be exploited as important tools in the assessment of disease status in humans. In the present review, we discuss different approaches used for the evaluation of OS in clinical samples. The described methods are limited in their ability to reflect on OS only partially, revealing the need of more integrative approaches examining both pro- and antioxidant reactions with higher sensitivity to physiological/pathological alternations. We also provide an overview of recent findings of OS in patients with different types of cancer. Identification of OS biomarkers in clinical samples of cancer patients and defining their roles in carcinogenesis hold great promise in promoting the development of targeted therapeutic approaches and diagnostic strategies assessing disease status. However, considerable data variability across laboratories makes it difficult to draw general conclusions on the significance of these OS biomarkers. To our knowledge, no adequate comparison has yet been performed between different biomarkers and the methodologies used to measure them, making it difficult to conduct a meta-analysis of findings from different groups. A critical evaluation and adaptation of proposed methodologies available in the literature should therefore be undertaken, to enable the investigators to choose the most suitable procedure for each chosen biomarker.