The transcription factor NRF2 enhances melanoma malignancy by blocking differentiation and inducing COX2 expression

RUNX1-induced upregulation of PTGS2 enhances cell growth, migration and invasion in colorectal cancer cells

Colorectal cancer (CRC) arises via the progressive accumulation of dysregulation in key genes including oncogenes and tumor-suppressor genes. Prostaglandin-endoperoxide synthase 2 (PTGS2, also called COX2) acts as an oncogenic driver in CRC. Here, we explored the upstream transcription factors (TFs) responsible for elevating PTGS2 expression in CRC cells. The results showed that PTGS2 silencing repressed cell growth, migration and invasion in HCT116 and SW480 CRC cells. The two fragments (499-981 bp) and (1053-1434 bp) were confirmed as the core TF binding profiles of the PTGS2 promoter. PTGS2 expression positively correlated with RUNX1 level in colon adenocarcinoma (COAD) samples using the TCGA-COAD dataset. Furthermore, RUNX1 acted as a positive regulator of PTGS2 expression by promoting transcriptional activation of the PTGS2 promoter via the 1086-1096 bp binding motif. In conclusion, our study demonstrates that PTGS2 upregulation induced by the TF RUNX1 promotes CRC cell growth, migration and invasion, providing an increased rationale for the use of PTGS2 inhibitors in CRC prevention and treatment.

NRF2 regulates EGF stability through OTUD4 in lung adenocarcinoma

NRF2 (NFE2L2) is a transcription factor mainly for regulating cellular antioxidant response and therefore promotes tumor progression. The target genes of NRF2 also play important roles in cellular processes including glucose metabolism, de novo serine synthesis, iron metabolism, etc. Here, by modulating NRF2 expression in lung adenocarcinoma (LUAD) cells, we showed that NRF2 regulated EGF expression at protein level. Furthermore, EGF was identified as a ubiquitinated protein. We predicted three deubiquitinases of EGF, and OTUD4 had the highest correlation with NRF2 in LUAD among the three. OTUD4 expression was reduced upon NRF2 knocking-down and recovered upon NRF2 rescuing in A549 cells. Then a potential binding site for NRF2 in OTUD4 promoter was searched out. By binding with OTUD4 promoter, NRF2 transcriptionally activated OTUD4, thus promoted EGF deubiquitination and enhanced its stability. More importantly, OTUD4 and NRF2 expression was found being correlated in LUAD patients. The data collectively revealed a novel mechanism of NRF2 regulating on EGF stability through OTUD4 in LUAD.

Modeling Melanoma Heterogeneity In Vitro: Redox, Resistance and Pigmentation Profiles

Microenvironment and transcriptional plasticity generate subpopulations within the tumor, and the use of BRAF inhibitors (BRAFis) contributes to the rise and selection of resistant clones. We stochastically isolated subpopulations (C1, C2, and C3) from naïve melanoma and found that the clones demonstrated distinct morphology, phenotypic, and functional profiles: C1 was less proliferative, more migratory and invasive, less sensitive to BRAFis, less dependent on OXPHOS, more sensitive to oxidative stress, and less pigmented; C2 was more proliferative, less migratory and invasive, more sensitive to BRAFis, less sensitive to oxidative stress, and more pigmented; and C3 was less proliferative, more migratory and invasive, less sensitive to BRAFis, more dependent on OXPHOS, more sensitive to oxidative stress, and more pigmented. Hydrogen peroxide plays a central role in oxidative stress and cell signaling, and PRDXs are one of its main consumers. The intrinsically resistant C1 and C3 clones had lower MITF, PGC-1α, and PRDX1 expression, while C1 had higher AXL and decreased pigmentation markers, linking PRDX1 to clonal heterogeneity and resistance. PRDX2 is depleted in acquired BRAFi-resistant cells and acts as a redox sensor. Our results illustrate that decreased pigmentation markers are related to therapy resistance and decreased antioxidant defense.

Harnessing the cGAS-STING pathway to potentiate radiation therapy: current approaches and future directions

In this review, we cover the current understanding of how radiation therapy, which uses ionizing radiation to kill cancer cells, mediates an anti-tumor immune response through the cGAS-STING pathway, and how STING agonists might potentiate this. We examine how cGAS-STING signaling mediates the release of inflammatory cytokines in response to nuclear and mitochondrial DNA entering the cytoplasm. The significance of this in the context of cancer is explored, such as in response to cell-damaging therapies and genomic instability. The contribution of the immune and non-immune cells in the tumor microenvironment is considered. This review also discusses the burgeoning understanding of STING signaling that is independent of inflammatory cytokine release and the various mechanisms by which cancer cells can evade STING signaling. We review the available data on how ionizing radiation stimulates cGAS-STING signaling as well as how STING agonists may potentiate the anti-tumor immune response induced by ionizing radiation. There is also discussion of how novel radiation modalities may affect cGAS-STING signaling. We conclude with a discussion of ongoing and planned clinical trials combining radiation therapy with STING agonists, and provide insights to consider when planning future clinical trials combining these treatments.

Thiol starvation triggers melanoma state switching in an ATF4 and NRF2-dependent manner

The cystine/glutamate antiporter xCT is an important source of cysteine for cancer cells. Once taken up, cystine is reduced to cysteine and serves as a building block for the synthesis of glutathione, which efficiently protects cells from oxidative damage and prevents ferroptosis. As melanomas are particularly exposed to several sources of oxidative stress, we investigated the biological role of cysteine and glutathione supply by xCT in melanoma. xCT activity was abolished by genetic depletion in the Tyr::CreER; BrafCA; Ptenlox/+ melanoma model and by acute cystine withdrawal in melanoma cell lines. Both interventions profoundly impacted melanoma glutathione levels, but they were surprisingly well tolerated by murine melanomas in vivo and by most human melanoma cell lines in vitro. RNA sequencing of human melanoma cells revealed a strong adaptive upregulation of NRF2 and ATF4 pathways, which orchestrated the compensatory upregulation of genes involved in antioxidant defence and de novo cysteine biosynthesis. In addition, the joint activation of ATF4 and NRF2 triggered a phenotypic switch characterized by a reduction of differentiation genes and induction of pro-invasive features, which was also observed after erastin treatment or the inhibition of glutathione synthesis. NRF2 alone was capable of inducing the phenotypic switch in a transient manner. Together, our data show that cystine or glutathione levels regulate the phenotypic plasticity of melanoma cells by elevating ATF4 and NRF2.

Total iridoid glycoside extract of Lamiophlomis rotata (Benth) Kudo accelerates diabetic wound healing by the NRF2/COX2 axis

BACKGROUND

Lamiophlomis rotata (Benth.) Kudo (L. rotata), the oral Traditional Tibetan herbal medicine, is adopted for treating knife and gun wounds for a long time. As previously demonstrated, total iridoid glycoside extract of L. rotata (IGLR) induced polarization of M2 macrophage to speed up wound healing. In diabetic wounds, high levels inflammatory and chemotactic factors are usually related to high reactive oxygen species (ROS) levels. As a ROS target gene, nuclear factor erythroid 2-related factor 2 (NRF2), influences the differentiation of monocytes to M1/M2 macrophages. Fortunately, iridoid glycosides are naturally occurring active compounds that can be used as the oxygen radical scavenger. Nevertheless, the influence of IGLR in diabetic wound healing and its associated mechanism is largely unclear.

MATERIALS AND METHODS

With macrophages and dermal fibroblasts in vitro, as well as a thickness excision model of db/db mouse in vivo, the role of IGLR in diabetic wound healing and the probable mechanism of the action were investigated.

RESULTS

Our results showed that IGLR suppressed oxidative distress and inflammation partly through the NRF2/cyclooxygenase2 (COX2) signaling pathway in vitro. The intercellular communication between macrophages and dermal fibroblasts was investigated by the conditioned medium (CM) of IGLR treatment cells. The CM increased the transcription and translation of collagen I (COL1A1) and alpha smooth muscle actin (α-SMA) within fibroblasts. With diabetic wound mice, the data demonstrated IGLR activated the NRF2/KEAP1 signaling and the downstream targets of the pathway, inhibited COX2/PEG2 signaling and decreased the interaction inflammatory targets of the axis, like interleukin-1beta (IL-1β), interleukin 6 (IL-6), apoptosis-associated speck-like protein (ASC), cysteinyl aspartate specific proteinase1 (caspase1) and NOD-like receptor-containing protein 3 (NLRP3).In addition, the deposition of COL1A1, and the level of α-SMA, and Transforming growth factor-β1 (TGF-β1) obviously elevated, whereas that of pro-inflammatory factors reduced in the diabetic wound tissue with IGLR treatment.

CONCLUSION

IGLR suppressed oxidative distress and inflammation mainly through NRF2/COX2 axis, thus promoting paracrine and accelerating wound healing in diabetes mice.

Nrf2 protein in melanoma progression, as a new means of treatment

Melanoma is a potentially lethal form of skin cancer resulting from the unlimited proliferation of melanocytes. Melanocytic lineage appears to have a greater rate of reactive oxygen species (ROS) production, possibly as a result of exposure to ultraviolet (UV) light and the production of melanin. It has been established that nuclear factor erythroid 2-related factor 2 (Nrf2) serves as a master regulator of the cellular response to oxidative stresses. Recent research has shown that the Nrf2 and its critical negative regulator Kelch-like ECH-associated protein 1 (Keap1) are misregulated in melanoma, and the Keap1-Nrf2 pathway has emerged as a promising new target for treating and preventing melanoma. In melanoma, Nrf2 may either limit tumor growth or promote its development. This review covers a wide range of topics, including the dual functions played by the Keap1-Nrf2 signaling pathway in melanoma and the most recent targeting techniques of the Nrf2.

Immune escape and metastasis mechanisms in melanoma: breaking down the dichotomy

Melanoma is one of the most lethal neoplasms of the skin. Despite the revolutionary introduction of immune checkpoint inhibitors, metastatic spread, and recurrence remain critical problems in resistant cases. Melanoma employs a multitude of mechanisms to subvert the immune system and successfully metastasize to distant organs. Concerningly, recent research also shows that tumor cells can disseminate early during melanoma progression and enter dormant states, eventually leading to metastases at a future time. Immune escape and metastasis have previously been viewed as separate phenomena; however, accumulating evidence is breaking down this dichotomy. Recent research into the progressive mechanisms of melanoma provides evidence that dedifferentiation similar to classical epithelial to mesenchymal transition (EMT), genes involved in neural crest stem cell maintenance, and hypoxia/acidosis, are important factors simultaneously involved in immune escape and metastasis. The likeness between EMT and early dissemination, and differences, also become apparent in these contexts. Detailed knowledge of the mechanisms behind "dual drivers" simultaneously promoting metastatically inclined and immunosuppressive environments can yield novel strategies effective in disabling multiple facets of melanoma progression. Furthermore, understanding progression through these drivers may provide insight towards novel treatments capable of preventing recurrence arising from dormant dissemination or improving immunotherapy outcomes.

NRF2/HO-1 axis, BIRC5, and TP53 expression in ESCC and its correlation with clinical pathological characteristics and prognosis

BACKGROUND

Many types of cancer exhibit high nuclear factor erythroid 2-related factor 2 (NRF2), which is effective in resisting drugs and radiation. However, the role of NRF2 gene expression in predicting the prognosis of esophageal squamous cell carcinoma (ESCC) remains unclear.

METHODS

The association between NRF2, heme oxygenase-1 (HO-1), baculovirus IAP repeat 5 (BIRC5), P53 gene expression levels and their relationship to immune-infiltrating cells were assessed using the Cancer Genome Atlas dataset, the Human Protein Atlas and the TISDB database. The expression of NRF2, HO-1, BIRC5, and TP53 in 118 ESCC patients was detected by immunohistochemistry, and the relationship between their expression level and clinicopathological parameters and prognosis was analyzed.

RESULTS

In ESCC, NRF2 overexpression was significantly associated with Han ethnicity, lymph node metastasis, and distant metastasis. HO-1 overexpression was significantly associated with differentiation, advanced clinical staging, lymph node metastasis, nerve invasion, and distant metastasis. BIRC5 overexpression was significantly associated with Han ethnicity and lymph node metastasis. TP53 overexpression was significantly associated with Han ethnicity and T staging. The NRF2/HO-1 axis expression was positively correlated with BIRC5 and TP53. Kaplan-Meier and multivariate Cox regression analysis showed that NRF2, BIRC5, and TP53 genes co-expression was an independent prognostic risk factor. TISIDB dataset analysis showed that immune-infiltrating cells were significantly negatively correlated with NRF2 and BIRC5.

CONCLUSION

NRF2, BIRC5, and TP53 axis gene expressions are predictors of poor prognosis for ESCC. The overexpression of the NRF2/HO-1/BIRC5 axis may not be related to immune-infiltrating cells.

New Treatment Horizons in Uveal and Cutaneous Melanoma

Melanoma is a complex and heterogeneous malignant tumor with distinct genetic characteristics and therapeutic challenges in both cutaneous melanoma (CM) and uveal melanoma (UM). This review explores the underlying molecular features and genetic alterations in these melanoma subtypes, highlighting the importance of employing specific model systems tailored to their unique profiles for the development of targeted therapies. Over the past decade, significant progress has been made in unraveling the molecular and genetic characteristics of CM and UM, leading to notable advancements in treatment options. Genetic mutations in the mitogen-activated protein kinase (MAPK) pathway drive CM, while UM is characterized by mutations in genes like GNAQ, GNA11, BAP1, EIF1AX, and SF3B1. Chromosomal aberrations, including monosomy 3 in UM and monosomy 10 in CM, play significant roles in tumorigenesis. Immune cell infiltration differs between CM and UM, impacting prognosis. Therapeutic advancements targeting these genetic alterations, including oncolytic viruses and immunotherapies, have shown promise in preclinical and clinical studies. Oncolytic viruses selectively infect malignant cells, inducing oncolysis and activating antitumor immune responses. Talimogene laherparepvec (T-VEC) is an FDA-approved oncolytic virus for CM treatment, and other oncolytic viruses, such as coxsackieviruses and HF-10, are being investigated. Furthermore, combining oncolytic viruses with immunotherapies, such as CAR-T cell therapy, holds great potential. Understanding the intrinsic molecular features of melanoma and their role in shaping novel therapeutic approaches provides insights into targeted interventions and paves the way for more effective treatments for CM and UM.

Advances in Understanding the Role of NRF2 in Liver Pathophysiology and Its Relationship with Hepatic-Specific Cyclooxygenase-2 Expression

Oxidative stress and inflammation play an important role in the pathophysiological changes of liver diseases. Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor that positively regulates the basal and inducible expression of a large battery of cytoprotective genes, thus playing a key role in protecting against oxidative damage. Cyclooxygenase-2 (COX-2) is a key enzyme in prostaglandin biosynthesis. Its expression has always been associated with the induction of inflammation, but we have shown that, in addition to possessing other benefits, the constitutive expression of COX-2 in hepatocytes is beneficial in reducing inflammation and oxidative stress in multiple liver diseases. In this review, we summarized the role of NRF2 as a main agent in the resolution of oxidative stress, the crucial role of NRF2 signaling pathways during the development of chronic liver diseases, and, finally we related its action to that of COX-2, where it appears to operate as its partner in providing a hepatoprotective effect.

The integrated stress response effector ATF4 is an obligatory metabolic activator of NRF2

The redox regulator NRF2 becomes activated upon oxidative and electrophilic stress and orchestrates a response program associated with redox regulation, metabolism, tumor therapy resistance, and immune suppression. Here, we describe an unrecognized link between the integrated stress response (ISR) and NRF2 mediated by the ISR effector ATF4. The ISR is commonly activated after starvation or ER stress and plays a central role in tissue homeostasis and cancer plasticity. ATF4 increases NRF2 transcription and induces the glutathione-degrading enzyme CHAC1, which we now show to be critically important for maintaining NRF2 activation. In-depth analyses reveal that NRF2 supports ATF4-induced cells by increasing cystine uptake via the glutamate-cystine antiporter xCT. In addition, NRF2 upregulates genes mediating thioredoxin usage and regeneration, thus balancing the glutathione decrease. In conclusion, we demonstrate that the NRF2 response serves as second layer of the ISR, an observation highly relevant for the understanding of cellular resilience in health and disease.

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.

The Multi-Faceted Consequences of NRF2 Activation throughout Carcinogenesis

The oxidative balance of a cell is maintained by the Kelch-like ECH-associated protein 1 (KEAP1)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway. This cytoprotective pathway detoxifies reactive oxygen species and xenobiotics. The role of the KEAP1/NRF2 pathway as pro-tumorigenic or anti-tumorigenic throughout stages of carcinogenesis (including initiation, promotion, progression, and metastasis) is complex. This mini review focuses on key studies describing how the KEAP1/NRF2 pathway affects cancer at different phases. The data compiled suggest that the roles of KEAP1/NRF2 in cancer are highly dependent on context; specifically, the model used (carcinogen-induced vs genetic), the tumor type, and the stage of cancer. Moreover, emerging data suggests that KEAP1/NRF2 is also important for regulating the tumor microenvironment and how its effects are amplified either by epigenetics or in response to co-occurring mutations. Further elucidation of the complexity of this pathway is needed in order to develop novel pharmacological tools and drugs to improve patient outcomes.

The dual role of Nrf2 in melanoma: a systematic review

Melanoma is the most lethal type of skin cancer that originates from the malignant transformation of melanocytes. Although novel treatments have improved patient survival in melanoma, the overall prognosis remains poor. To improve current therapies and patients outcome, it is necessary to identify the influential elements in the development and progression of melanoma.Due to UV exposure and melanin synthesis, the melanocytic lineage seems to have a higher rate of ROS (reactive oxygen species) formation. Melanoma has been linked to an increased oxidative state, and all facets of melanoma pathophysiology rely on redox biology. Several redox-modulating pathways have arisen to resist oxidative stress. One of which, the Nrf2 (nuclear factor erythroid 2-related factor 2), has been recognized as a master regulator of cellular response to oxidative or electrophilic challenges. The activation of Nrf2 signaling causes a wide range of antioxidant and detoxification enzyme genes to be expressed. As a result, this transcription factor has lately received a lot of interest as a possible cancer treatment target.On the other hand, Nrf2 has been found to have a variety of activities in addition to its antioxidant abilities, constant Nrf2 activation in malignant cells may accelerate metastasis and chemoresistance. Hence, based on the cell type and context, Nrf2 has different roles in either preventing or promoting cancer. In this study, we aimed to systematically review all the studies discussing the function of Nrf2 in melanoma and the factors determining its alteration.

Momordica cochinchinensis (Gấc) Seed Extracts Induce Apoptosis and Necrosis in Melanoma Cells

Momordica cochinchinensis is a herbal medicine used throughout Asia and this study investigated the antimelanoma potentials and molecular mechanisms of M. cochinchinensis seed with emphasis on extraction to optimise bioactivity. Overall, the aqueous extract was superior, with a wider diversity and higher concentration of proteins and peptides that was more cytotoxic to the melanoma cells than other extraction solvents. The IC50 of the aqueous extract on melanoma cells were similar to treatment with current anticancer drugs, vemurafenib and cisplatin. This cytotoxicity was cancer-specific with lower cytotoxic effects on HaCaT epidermal keratinocytes. Cytotoxicity correlated with MAPK signalling pathways leading to apoptosis and necrosis induced by triggering tumour necrosis factor receptor-1 (TNFR1), reducing the expression of nuclear factor kappa B (NF-kB), and suppression of BRAF/MEK. This efficacy of M. cochinchinensis seed extracts on melanoma cells provides a platform for future clinical trials as potent adjunctive therapy for metastatic melanoma.

Targeting oncogenic transcription factors in skin malignancies: An update on cancer stemness and therapeutic outcomes

The skin is the largest organ of the human body and prone to various diseases, including cancer; thus, provides the first line of defense against exogenous biological and non-biological agents. Skin cancer, a complex and heterogenic process, with steep incidence rate often metastasizes due to poor understanding of the underlying mechanisms of pathogenesis and clinical challenges. Indeed, accumulating evidence indicates that deregulation of transcription factors (TFs) due to genetic, epigenetic and signaling distortions plays essential role in the development of cutaneous malignancies and therapeutic challenges including cancer stemness features and reprogramming. This review highlights the recent developments exploring underlying mechanisms how deregulated TFs (e.g., NF-κB, AP-1, STAT etc.,) orchestrates cutaneous onco-pathogenesis, reprogramming, stemness and poor clinical outcomes. Along this line, bioactive drugs, and their derivatives from natural and or synthetic origin has gained attention due to their multitargeting potential, potentially safer and effective therapeutic outcome for human malignancies. We also discussed therapeutic importance of targeting aberrantly expressed TFs in skin cancers with bioactive natural products and or synthetic agents.

Extending the Mass Spectrometry-Detectable Landscape of MHC Peptides by Use of Restricted Access Material

Mass spectrometry-based immunopeptidomics enables the comprehensive identification of major histocompatibility complex (MHC) peptides from a cell culture as well as from tissue or tumor samples and is applied for the identification of tumor-specific and viral T-cell epitopes. Although mass spectrometry is generally considered an "unbiased" method for MHC peptide identification, the physicochemical properties of MHC peptides can greatly influence their detectability. Here, we demonstrate that highly hydrophobic peptides are lost during sample preparation when C18 solid-phase extraction (SPE) is used for separating MHC peptides from proteins. To overcome this limitation, we established an optimized protocol involving restricted access material (RAM). Compared to C18-SPE, RAM-SPE improved the overall MHC peptide recovery and extended the landscape of mass spectrometry-detectable MHC peptides toward more hydrophobic peptides.

Regulation of innate immunity by Nrf2

The transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2) has been mainly investigated as a regulator of redox homeostasis. However, research over the past years has implicated Nrf2 as an important regulator of innate immunity. Here, we discuss the role of Nrf2 in the innate immune response, highlighting the interaction between Nrf2 and major components of the innate immune system. Indeed, Nrf2 has been shown to widely control the immune response by interacting directly or indirectly with important innate immune components, including the toll-like receptors-Nuclear factor kappa B (NF-kB) pathway, inflammasome signaling, and the type-I interferon response. This indicates an essential role for Nrf2 in diseases related to microbial infections, inflammation, and cancer. Yet, further studies are required to determine the exact mechanism underpinning the interactions between Nrf2 and innate immune players in order to allow a better understanding of these diseases and leverage new therapeutic strategies.

Identification of Key Genes and FUNCTIONAL Pathway in Radioresistance of Non-Small Cell Lung Cancer

Purpose

For better understanding of radiotherapy resistance and its potential mechanism.

Methods

We established radioresistance cell lines of non-small cell lung cancer (NSCLC) followed by microarray analysis. 529 differentially expressed genes (DEGs) were then screened between radiation resistant cell lines compared with the sensitive cell lines. The biological functions and enrichment pathways of the above DEGs were identified using Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) enrichment analyses. Gene Set Enrichment Analysis (GSEA) revealed that the radiation resistance group had the most gene sets enriched in altered immune response, such as TNF signaling pathway, when compared to the radiation sensitive group. Protein-protein interaction (PPI) network was carried out through the STRING database, and then five hub genes (CXCL10, IFIH1, DDX58, CXCL11, RSAD2) were screened by Cytoscape software. RT-PCR confirmed the expression of the above hub genes. ChIP-X Enrichment Analysis showed that STAT1 might be the transcription factor of the above hub genes. Considering that PD-L1 could be activated by STAT1 in a variety of tumors and ultimately lead to immune exhaustion, RT-PCR and Western blot verified the expression level of PD-L1.

Results

Five hub genes (CXCL10, IFIH1, DDX58, CXCL11, RSAD2) were screened and verified to be highly expressed in radioresistance group, STAT1 might be the transcription factor of the above hub genes. Our study found that the expression level of PD-L1 was increased after radiotherapy resistance.

Conclusion

Although immune system activation occurs followed by radiation resistance, we hypothesized that the upregulation of PD-L1 expression caused by STAT1 activation might be one of the mechanisms of radiotherapy resistance.

NRF2-directed PRPS1 upregulation to promote the progression and metastasis of melanoma

Phosphoribosyl pyrophosphate synthetase 1 (PRPS1) is the first enzyme in the de novo purine nucleotide synthesis pathway and is essential for cell development. However, the effect of PRPS1 on melanoma proliferation and metastasis remains unclear. This study aimed to investigate the regulatory mechanism of PRPS1 in the malignant progression of melanoma. Here, we found PRPS1 was upregulated in melanoma and melanoma cells. In addition, our data indicated that PRPS1 could promote the proliferation and migration and invasion of melanoma both in vitro and in vivo. PRPS1 also could inhibit melanoma cell apoptosis. Furthermore, we found NRF2 is an upstream transcription factor of PRPS1 that drive malignant progression of melanoma.

Identification of Age-Associated Transcriptomic Changes Linked to Immunotherapy Response in Primary Melanoma

Melanoma is a lethal form of skin cancer. Immunotherapeutic agents such as anti-PD-1 (pembrolizumab and nivolumab) and anti-CTLA-4 (ipilimumab) have revolutionized melanoma treatment; however, drug resistance is rapidly acquired. Several studies have reported an increase in melanoma rates in older patients. Thus, the impact of ageing on transcriptional profiles of melanoma and response to immunotherapy is essential to understand. In this study, the bioinformatic analysis of RNA seq data of old and young melanoma patients receiving immunotherapy identifies the significant upregulation of extra-cellular matrix and cellular adhesion genes in young cohorts, while genes involved in cell proliferation, inflammation, non-canonical Wnt signaling and tyrosine kinase receptor ROR2 are significantly upregulated in the old cohort. Several Treg signature genes as well as transcription factors that are associated with dysfunctional T cell tumor infiltration are differentially expressed. The differential expression of several genes involved in oxidative phosphorylation, glycolysis and glutamine metabolism is also observed. Taken together, this study provides novel findings on the impact of ageing on transcriptional changes in melanoma, and novel therapeutic targets for future studies.

Mapping phenotypic heterogeneity in melanoma onto the epithelial-hybrid-mesenchymal axis

Epithelial to mesenchymal transition (EMT) is a well-studied hallmark of epithelial-like cancers that is characterized by loss of epithelial markers and gain of mesenchymal markers. Melanoma, which is derived from melanocytes of the skin, also undergo phenotypic plasticity toward mesenchymal-like phenotypes under the influence of various micro-environmental cues. Our study connects EMT to the phenomenon of de-differentiation (i.e., transition from proliferative to more invasive phenotypes) observed in melanoma cells during drug treatment. By analyzing 78 publicly available transcriptomic melanoma datasets, we found that de-differentiation in melanoma is accompanied by upregulation of mesenchymal genes, but not necessarily a concomitant loss of an epithelial program, suggesting a more “one-dimensional” EMT that leads to a hybrid epithelial/mesenchymal phenotype. Samples lying in the hybrid epithelial/mesenchymal phenotype also correspond to the intermediate phenotypes in melanoma along the proliferative-invasive axis - neural crest and transitory ones. As melanoma cells progress along the invasive axis, the mesenchymal signature does not increase monotonically. Instead, we observe a peak in mesenchymal scores followed by a decline, as cells further de-differentiate. This biphasic response recapitulates the dynamics of melanocyte development, suggesting close interactions among genes controlling differentiation and mesenchymal programs in melanocytes. Similar trends were noted for metabolic changes often associated with EMT in carcinomas in which progression along mesenchymal axis correlates with the downregulation of oxidative phosphorylation, while largely maintaining glycolytic capacity. Overall, these results provide an explanation for how EMT and de-differentiation axes overlap with respect to their transcriptional and metabolic programs in melanoma.

NRF2 in dermatological disorders: Pharmacological activation for protection against cutaneous photodamage and photodermatosis

The skin barrier and its endogenous protective mechanisms cope daily with exogenous stressors, of which ultraviolet radiation (UVR) poses an imminent danger. Although the skin is able to reduce the potential damage, there is a need for comprehensive strategies for protection. This is particularly important when developing pharmacological approaches to protect against photocarcinogenesis. Activation of NRF2 has the potential to provide comprehensive and long-lasting protection due to the upregulation of numerous cytoprotective downstream effector proteins that can counteract the damaging effects of UVR. This is also applicable to photodermatosis conditions that exacerbate the damage caused by UVR. This review describes the alterations caused by UVR in normal skin and photosensitive disorders, and provides evidence to support the development of NRF2 activators as pharmacological treatments. Key natural and synthetic activators with photoprotective properties are summarized. Lastly, the gap in knowledge in research associated with photodermatosis conditions is highlighted.

Connecting Metabolic Rewiring With Phenotype Switching in Melanoma

Melanoma is a complex and aggressive cancer type that contains different cell subpopulations displaying distinct phenotypes within the same tumor. Metabolic reprogramming, a hallmark of cell transformation, is essential for melanoma cells to adopt different phenotypic states necessary for adaptation to changes arising from a dynamic milieu and oncogenic mutations. Increasing evidence demonstrates how melanoma cells can exhibit distinct metabolic profiles depending on their specific phenotype, allowing adaptation to hostile microenvironmental conditions, such as hypoxia or nutrient depletion. For instance, increased glucose consumption and lipid anabolism are associated with proliferation, while a dependency on exogenous fatty acids and an oxidative state are linked to invasion and metastatic dissemination. How these different metabolic dependencies are integrated with specific cell phenotypes is poorly understood and little is known about metabolic changes underpinning melanoma metastasis. Recent evidence suggests that metabolic rewiring engaging transitions to invasion and metastatic progression may be dependent on several factors, such as specific oncogenic programs or lineage-restricted mechanisms controlling cell metabolism, intra-tumor microenvironmental cues and anatomical location of metastasis. In this review we highlight how the main molecular events supporting melanoma metabolic rewiring and phenotype-switching are parallel and interconnected events that dictate tumor progression and metastatic dissemination through interplay with the tumor microenvironment.

Activation of Nrf2 in Mice Causes Early Microvascular Cyclooxygenase-Dependent Oxidative Stress and Enhanced Contractility

Nuclear factor erythroid factor E2-related factor 2 (Nrf2) transcribes antioxidant genes that reduce the blood pressure (BP), yet its activation with tert-butylhydroquinone (tBHQ) in mice infused with angiotensin II (Ang II) increased mean arterial pressure (MAP) over the first 4 days of the infusion. Since tBHQ enhanced cyclooxygenase (COX) 2 expression in vascular smooth muscle cells (VSMCs), we tested the hypothesis that tBHQ administration during an ongoing Ang II infusion causes an early increase in microvascular COX-dependent reactive oxygen species (ROS) and contractility. Mesenteric microarteriolar contractility was assessed on a myograph, and ROS by RatioMaster™. Three days of oral tBHQ administration during the infusion of Ang II increased the mesenteric microarteriolar mRNA for p47^phox, the endothelin type A receptor and thromboxane A₂ synthase, and increased the excretion of 8-isoprostane F_2α and the microarteriolar ROS and contractions to a thromboxane A₂ (TxA₂) agonist (U-46,619) and endothelin 1 (ET1). These were all prevented in Nrf2 knockout mice. Moreover, the increases in ROS and contractility were prevented in COX1 knockout mice with blockade of COX2 and by blockade of thromboxane prostanoid receptors (TPRs). In conclusion, the activation of Nrf2 over 3 days of Ang II infusion enhances microarteriolar ROS and contractility, which are dependent on COX1, COX2 and TPRs. Therefore, the blockade of these pathways may diminish the early adverse cardiovascular disease events that have been recorded during the initiation of Nrf2 therapy.

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.

Redox sensitive miR-27a/b/Nrf2 signaling in Cr(VI)-induced carcinogenesis

Hexavalent chromium [Cr(VI)] is a well-known carcinogen that can cause several types of cancer including lung cancer. NF-E2-related factor 2 (Nrf2), the redox sensitive transcription factor, can protect normal cells from a variety of toxicants and carcinogens by inducing the expression of cellular protective genes and maintaining redox balance. However, Nrf2 also protects cancer cells from radio- and chemo-therapies and facilitates cancer progression. Although Cr(VI) treatment has been demonstrated to upregulate Nrf2 expression, the mechanisms for Nrf2 regulation upon chronic Cr(VI) exposure remain to be elucidated. We found that Nrf2 was upregulated in BEAS-2B cells exposed to Cr(VI) from 1 to 5 months, and also in Cr(VI)-induced transformed (Cr-T) cells with Cr(VI) treatment for 6 months. We showed that KEAP1, the classic negative regulator of Nrf2, was downregulated after Cr(VI) exposure for 4 months, suggesting that Nrf2 induction by Cr(VI) treatment is through KEAP1 decrease at late stage. To further decipher the mechanisms of Nrf2 upregulation at early stage of Cr(VI) exposure, we demonstrated that miR-27a and miR-27b were redox sensitive miRNAs, since reactive oxygen species (ROS) scavengers induced miR-27a/b expression. After Cr(VI) exposure for 1 month, the expression levels of miR-27a/b was dramatically decreased. The changes of miR-27a/b and their target Nrf2 were confirmed in vivo by mouse model intranasally exposed to Cr(VI) for 12 weeks. Nrf2 was a direct target of miR-27a/b, which acted as tumor suppressors in vitro and in vivo to inhibit tumorigenesis and cancer development of Cr-T cells. The results suggested that the inhibition of miR-27a/b was responsible for Nrf2 upregulation at both early stage and late stage of Cr(VI) exposure. This novel regulation of Nrf2 upon chronic Cr(VI) exposure through redox-regulated miR-27a/b will provide potential targets for preventing and treating Cr(VI)-induced carcinogenesis in the future.

Ferroptosis: regulation by competition between NRF2 and BACH1 and propagation of the death signal

Ferroptosis is triggered by a chain of intracellular labile iron-dependent peroxidation of cell membrane phospholipids. Ferroptosis is important not only as a cause of ischaemic and neurodegenerative diseases but also as a mechanism of cancer suppression, and a better understanding of its regulatory mechanism is required. It has become clear that ferroptosis is finely controlled by two oxidative stress-responsive transcription factors, NRF2 (NF-E2-related factor 2) and BACH1 (BTB and CNC homology 1). NRF2 and BACH1 inhibit and promote ferroptosis, respectively, by activating or suppressing the expression of genes in the major regulatory pathways of ferroptosis: intracellular labile iron metabolism, the GSH (glutathione) -GPX4 (glutathione peroxidase 4) pathway and the FSP1 (ferroptosis suppressor protein 1)-CoQ (coenzyme Q) pathway. In addition to this, NRF2 and BACH1 control ferroptosis through the regulation of lipid metabolism and cell differentiation. This multifaceted regulation of ferroptosis by NRF2 and BACH1 is considered to have been acquired during the evolution of multicellular organisms, allowing the utilization of ferroptosis for maintaining homeostasis, including cancer suppression. In terms of cell-cell interaction, it has been revealed that ferroptosis has the property of propagating to surrounding cells along with lipid peroxidation. The regulation of ferroptosis by NRF2 and BACH1 and the propagation phenomenon could be used to realize anticancer cell therapy in the future. In this review, these points will be summarized and discussed.

Transcript Expression Profiles and MicroRNA Regulation Indicate an Upregulation of Processes Linked to Oxidative Stress, DNA Repair, Cell Death, and Inflammation in Type 1 Diabetes Mellitus Patients

Type 1 diabetes (T1D) arises from autoimmune-mediated destruction of insulin-producing β-cells leading to impaired insulin secretion and hyperglycemia. T1D is accompanied by DNA damage, oxidative stress, and inflammation, although there is still scarce information about the oxidative stress response and DNA repair in T1D pathogenesis. We used the microarray method to assess mRNA expression profiles in peripheral blood mononuclear cells (PBMCs) of 19 T1D patients compared to 11 controls and identify mRNA targets of microRNAs that were previously reported for T1D patients. We found 277 differentially expressed genes (220 upregulated and 57 downregulated) in T1D patients compared to controls. Analysis by gene sets (GSA and GSEA) showed an upregulation of processes linked to ROS generation, oxidative stress, inflammation, cell death, ER stress, and DNA repair in T1D patients. Besides, genes related to oxidative stress responses and DNA repair (PTGS2, ATF3, FOSB, DUSP1, and TNFAIP3) were found to be targets of four microRNAs (hsa-miR-101, hsa-miR148a, hsa-miR-27b, and hsa-miR-424). The expression levels of these mRNAs and microRNAs were confirmed by qRT-PCR. Therefore, the present study on differential expression profiles indicates relevant biological functions related to oxidative stress response, DNA repair, inflammation, and apoptosis in PBMCs of T1D patients relative to controls. We also report new insights regarding microRNA-mRNA interactions, which may play important roles in the T1D pathogenesis.

Ozone Responsive Gene Expression as a Model for Describing Repeat Exposure Response Trajectories and Interindividual Toxicodynamic Variability In Vitro

Inhaled chemical/material exposures are a ubiquitous part of daily life around the world. There is a need to evaluate potential adverse effects of both single and repeat exposures for thousands of chemicals and an exponentially larger number of exposure scenarios (eg, repeated exposures). Meeting this challenge will require the development and use of in vitro new approach methodologies (NAMs); however, 2 major challenges face the deployment of NAMs in risk assessment are (1) characterizing what apical outcome(s) acute assays inform regarding the trajectory to long-term events, especially under repeated exposure conditions, and (2) capturing interindividual variability as it informs considerations of potentially susceptible and/or vulnerable populations. To address these questions, we used a primary human bronchial epithelial cell air-liquid interface model exposed to ozone (O3), a model oxidant and ubiquitous environmental chemical. Here we report that O3-induced proinflammatory gene induction is attenuated in repeated exposures thus demonstrating that single acute exposure outcomes do not reliably represent the trajectory of responses after repeated or chronic exposures. Further, we observed 10.1-, 10.3-, 14.2-, and 7-fold ranges of induction of interleukin (IL)-8, IL-6, heme oxygenase 1, and cyclooxygenase 2 transcripts, respectively, within in our population of 25 unique donors. Calculation of sample size estimates that indicated that 27, 24, 299, and 13 donors would be required to significantly power similar in vitro studies to identify a 2-fold change in IL-8, IL-6, HMOX1, and cyclooxygenase 2 transcript induction, respectively, to inform considerations of the uncertainty factors to reflect variability within the human population for in vitro studies.

Proteome analysis of NRF2 inhibition in melanoma reveals CD44 up-regulation and increased apoptosis resistance upon vemurafenib treatment

Malignant melanoma is the deadliest form of skin cancer and NRF2 has been proposed as a main regulator of tumor cell malignancy. Still the mechanisms how NRF2 is contributing to melanoma progression are incompletely understood. Here we analyzed the effects of either NRF2 induction or depletion, and we also quantified changes on the whole cell proteome level. Our results showed that inhibition of NRF2 leads to a loss of reactive oxygen species protection, but at the same time to an induction of an epithelial mesenchymal transition (EMT) phenotype and an up‐regulation of the stem cell marker CD44. Additionally, cells devoid of NRF2 showed increased cell viability after treatment with a MYC and a BRAF inhibitor. Importantly, survival upon vemurafenib treatment was dependent on CD44 expression. Finally, analysis of archival melanoma patient samples confirmed a vice versa relationship of NRF2 and CD44 expression. In summary, we recorded changes in the proteome after NRF2 modulation in melanoma cells. Surprisingly, we identified that NRF2 inhibition lead to induction of an EMT phenotype and an increase in survival of cells after apoptosis induction. Therefore, we propose that it is important for future therapies targeting NRF2 to consider blocking EMT promoting pathways in order to achieve efficient tumor therapy.

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.

4-Octyl-Itaconate and Dimethyl Fumarate Inhibit COX2 Expression and Prostaglandin Production in Macrophages

Prostaglandins (PGs) are important proinflammatory lipid mediators, the significance of which is highlighted by the widespread and efficacious use of non-steroidal anti-inflammatory drugs (NSAIDs) in the treatment of inflammation. 4-Octyl itaconate (4-OI), a derivative of the Krebs cycle-derived metabolite itaconate, has recently garnered much interest as an anti-inflammatory agent. Here we show that 4-OI limits PG production in macrophages stimulated with the Toll-like receptor 1/2 (TLR1/2) ligand Pam3CSK4. This decrease in PG secretion is due to a robust suppression of COX2 expression by 4-OI, with both mRNA and protein levels decreased. Dimethyl fumarate (DMF), a fumarate derivative used in the treatment of multiple sclerosis (MS), with properties similar to itaconate, replicated the phenotype observed with 4-OI. We also demonstrate that the decrease in COX2 expression and inhibition of downstream prostaglandin production occurs in an NRF2-independent manner. Our findings provide a new insight into the potential of 4-OI as an anti-inflammatory agent and also identifies a novel anti-inflammatory function of DMF.

Melanoma Plasticity: Promoter of Metastasis and Resistance to Therapy

Melanoma is the deadliest form of skin cancer. Although targeted therapies and immunotherapies have revolutionized the treatment of metastatic melanoma, most patients are not cured. Therapy resistance remains a significant clinical challenge. Melanoma comprises phenotypically distinct subpopulations of cells, exhibiting distinct gene signatures leading to tumor heterogeneity and favoring therapeutic resistance. Cellular plasticity in melanoma is referred to as phenotype switching. Regardless of their genomic classification, melanomas switch from a proliferative and differentiated phenotype to an invasive, dedifferentiated and often therapy-resistant state. In this review we discuss potential mechanisms underpinning melanoma phenotype switching, how this cellular plasticity contributes to resistance to both targeted therapies and immunotherapies. Finally, we highlight novel strategies to target plasticity and their potential clinical impact in melanoma.

Interplay of Immunometabolism and Epithelial-Mesenchymal Transition in the Tumor Microenvironment

Epithelial–mesenchymal transition (EMT) and metabolic reprogramming in cancer cells are the key hallmarks of tumor metastasis. Since the relationship between the two has been well studied, researchers have gained increasing interest in the interplay of cancer cell EMT and immune metabolic changes. Whether the mutual influences between them could provide novel explanations for immune surveillance during metastasis is worth understanding. Here, we review the role of immunometabolism in the regulatory loop between tumor-infiltrating immune cells and EMT. We also discuss the challenges and perspectives of targeting immunometabolism in cancer treatment.

The Identification of the Metabolism Subtypes of Skin Cutaneous Melanoma Associated With the Tumor Microenvironment and the Immunotherapy

Skin cutaneous melanoma (SKCM) is a highly aggressive and resistant cancer with immense metabolic heterogeneity. Here, we performed a comprehensive examination of the diverse metabolic signatures of SKCM based on non-negative matrix factorization (NMF) categorization, clustering SKCM into three distinct metabolic subtypes (C1, C2, and C3). Next, we evaluated the metadata sets of the metabolic signatures, prognostic values, transcriptomic features, tumor microenvironment signatures, immune infiltration, clinical features, drug sensitivity, and immunotherapy response of the subtypes and compared them with those of prior publications for classification. Subtype C1 was associated with high metabolic activity, low immune scores, and poor prognosis. Subtype C2 displayed low metabolic activity, high immune infiltration, high stromal score, and high expression of immune checkpoints, demonstrating the drug sensitivity to PD-1 inhibitors. The C3 subtype manifested moderate metabolic activity, high enrichment in carcinogenesis-relevant pathways, high levels of CpG island methylator phenotype (CIMP), and poor prognosis. Eventually, a 90-gene classifier was produced to implement the SKCM taxonomy and execute a consistency test in different cohorts to validate its reliability. Preliminary validation was performed to ascertain the role of SLC7A4 in SKCM. These results indicated that the 90-gene signature can be replicated to stably identify the metabolic classification of SKCM. In this study, a novel SKCM classification approach based on metabolic gene expression profiles was established to further understand the metabolic diversity of SKCM and provide guidance on precisely targeted therapy to patients with the disease.

Targeted Inhibition of Anti-Inflammatory Regulator Nrf2 Results in Breast Cancer Retardation In Vitro and In Vivo

Nuclear factor erythroid-2 related factor-2 (Nrf2) is an oxidative stress-response transcriptional activator that promotes carcinogenesis through metabolic reprogramming, tumor promoting inflammation, and therapeutic resistance. However, the extension of Nrf2 expression and its involvement in regulation of breast cancer (BC) responses to chemotherapy remain largely unclear. This study determined the expression of Nrf2 in BC tissues (n = 46) and cell lines (MDA-MB-453, MCF-7, MDA-MB-231, MDA-MB-468) with diverse phenotypes. Immunohistochemical (IHC)analysis indicated lower Nrf2 expression in normal breast tissues, compared to BC samples, although the difference was not found to be significant. However, pharmacological inhibition and siRNA-induced downregulation of Nrf2 were marked by decreased activity of NADPH quinone oxidoreductase 1 (NQO1), a direct target of Nrf2. Silenced or inhibited Nrf2 signaling resulted in reduced BC proliferation and migration, cell cycle arrest, activation of apoptosis, and sensitization of BC cells to cisplatin in vitro. Ehrlich Ascites Carcinoma (EAC) cells demonstrated elevated levels of Nrf2 and were further tested in experimental mouse models in vivo. Intraperitoneal administration of pharmacological Nrf2 inhibitor brusatol slowed tumor cell growth. Brusatol increased lymphocyte trafficking towards engrafted tumor tissue in vivo, suggesting activation of anti-cancer effects in tumor microenvironment. Further large-scale BC testing is needed to confirm Nrf2 marker and therapeutic capacities for chemo sensitization in drug resistant and advanced tumors.

The Good and Bad of Nrf2: An Update in Cancer and New Perspectives in COVID-19

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a well-known transcription factor best recognised as one of the main regulators of the oxidative stress response. Beyond playing a crucial role in cell defence by transactivating cytoprotective genes encoding antioxidant and detoxifying enzymes, Nrf2 is also implicated in a wide network regulating anti-inflammatory response and metabolic reprogramming. Such a broad spectrum of actions renders the factor a key regulator of cell fate and a strategic player in the control of cell transformation and response to viral infections. The Nrf2 protective roles in normal cells account for its anti-tumour and anti-viral functions. However, Nrf2 overstimulation often occurs in tumour cells and a complex correlation of Nrf2 with cancer initiation and progression has been widely described. Therefore, if on one hand, Nrf2 has a dual role in cancer, on the other hand, the factor seems to display a univocal function in preventing inflammation and cytokine storm that occur under viral infections, specifically in coronavirus disease 19 (COVID-19). In such a variegate context, the present review aims to dissect the roles of Nrf2 in both cancer and COVID-19, two widespread diseases that represent a cause of major concern today. In particular, the review describes the molecular aspects of Nrf2 signalling in both pathological situations and the most recent findings about the advantages of Nrf2 inhibition or activation as possible strategies for cancer and COVID-19 treatment respectively.

The developmental origin of cancers defines basic principles of cisplatin resistance

Cisplatin-based chemotherapy has been used for more than four decades as a standard therapeutic option in several tumor entities. However, being a multifaceted and heterogeneous phenomenon, inherent or acquired resistance to cisplatin remains a major obstacle during the treatment of several solid malignancies and inevitably results in disease progression. Hence, we felt there was an urgent need to evaluate common mechanisms between multifarious cancer entities to identify patient-specific therapeutic strategies. We found joint molecular and (epi)genetic resistance mechanisms and specific cisplatin-induced mutational signatures that depended on the developmental origin (endo-, meso-, ectoderm) of the tumor tissue. Based on the findings of thirteen tumor entities, we identified three resistance groups, where Group 1 (endodermal origin) prominently indicates NRF2-pathway activation, Group 2 (mesodermal origin, primordial germ cells) shares elevated DNA repair mechanisms and decreased apoptosis induction, and Group 3 (ectodermal and paraxial mesodermal origin) commonly presents deregulated apoptosis induction and alternating pathways as the main cisplatin-induced resistance mechanisms. This review further proposes potential and novel therapeutic strategies to improve the outcome of cisplatin-based chemotherapy.

A Novel Ruthenium(II) Complex With Lapachol Induces G2/M Phase Arrest Through Aurora-B Kinase Down-Regulation and ROS-Mediated Apoptosis in Human Prostate Adenocarcinoma Cells

Lapachol is a well-studied natural product that has been receiving great interest due to its anticancer properties that target oxidative stress. In the present work, two novel lapachol-containing ruthenium(II) complexes [Ru(Lap)(dppm)(bipy)]PF6 (1) and [Ru(Lap)(dppm)(phen)]PF6 (2) [Lap = lapachol, dppm = 1,1'-bis(diphosphino)methane, bipy = 2,2'-bipyridine, phen = 1,10-phenantroline] were synthesized, fully characterized, and investigated for their cellular and molecular responses on cancer cell lines. We found that both complexes exhibited a potent cytotoxic effect in a panel of cancer cell lines in monolayer cultures, as well as in a 3D model of multicellular spheroids formed from DU-145 human prostate adenocarcinoma cells. Furthermore, the complex (2) suppressed the colony formation, induced G2/M-phase arrest, and downregulated Aurora-B. The mechanism studies suggest that complex (2) stimulate the overproduction of reactive oxygen species (ROS) and triggers caspase-dependent apoptosis as a result of changes in expression of several genes related to cell proliferation and caspase-3 and -9 activation. Interestingly, we found that N-acetyl-L-cysteine, a ROS scavenger, suppressed the generation of intracellular ROS induced by complex (2), and decreased its cytotoxicity, indicating that ROS-mediated DNA damage leads the DU-145 cells into apoptosis. Overall, we highlighted that coordination of lapachol to phosphinic ruthenium(II) compounds considerably improves the antiproliferative activities of resulting complexes granting attractive selectivity to human prostate adenocarcinoma cells. The DNA damage response to ROS seems to be involved in the induction of caspase-mediated cell death that plays an important role in the complexes' cytotoxicity. Upon further investigations, this novel class of lapachol-containing ruthenium(II) complexes might indicate promising chemotherapeutic agents for prostate cancer therapy.

The Protective Effect of Polyherbal Formulation, Harak Formula, on UVA-Induced Photoaging of Human Dermal Fibroblasts and Mouse Skin via Promoting Nrf2-Regulated Antioxidant Defense

Polyherbal formulation combining multiple herbs is suggested to achieve enhanced therapeutic effects and reduce toxicity. Harak herbal formula (HRF) extracts were proposed to regulate skin responses to UVR through their ability to suppress UVA-induced matrix metalloproteinase-1 (MMP-1) and pigmentation via promoting antioxidant defenses in in vitro models. Therefore, natural products targeting Nrf2 (nuclear factor erythroid 2-related factor 2)-regulated antioxidant response might represent promising anti-photoaging candidates. Hesperetin (HSP) was suggested as a putative bioactive compound of the HRF, as previously shown by its chemical profiling using the liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). In this study, we explored the anti-photoaging effects of HRF extracts and HSP on normal human dermal fibroblasts (NHDFs) and mouse skin exposed to UVA irradiation. Pretreatment of NHDFs with HRF extracts and HSP protected against UVA (8 J/cm²)-mediated cytotoxicity and reactive oxygen species (ROS) formation. The HRF and HSP pretreatment also attenuated the UVA-induced MMP-1 activity and collagen depletion concomitant with an upregulation of Nrf2 activity and its downstream genes (GST and NQO-1). Moreover, our findings provided the in vivo relevance to the in vitro anti-photoaging effects of HRF as topical application of the extracts (10, 30 and 100 mg/cm²) and HSP (0.3, 1, and 3 mg/cm²) 1 h before UVA exposure 3 times per week for 2 weeks (a total dose of 60 J/cm²) mitigated MMP-1 upregulation, collagen loss in correlation with enhanced Nrf2 nuclear accumulation and its target protein GST and NQO-1 as well as reduced 8-hydroxy-2′-deoxyguanosine (8-OHdG) in irradiated mouse skin. Thus, our findings revealed that HRF extracts and HSP attenuated UVA-induced photoaging via upregulating Nrf2, together with their abilities to reduce ROS formation and oxidative damage. Our study concluded that the HRF and its bioactive ingredient HSP may represent potential candidates for preventing UVA-induced photoaging via restoration of redox balance.

NRF2 Enables EGFR Signaling in Melanoma Cells

Receptor tyrosine kinases (RTK) are rarely mutated in cutaneous melanoma, but the expression and activation of several RTK family members are associated with a proinvasive phenotype and therapy resistance. Epidermal growth factor receptor (EGFR) is a member of the RTK family and is only expressed in a subgroup of melanomas with poor prognosis. The insight into regulators of EGFR expression and activation is important for the understanding of the development of this malignant melanoma phenotype. Here, we describe that the transcription factor NRF2, the master regulator of the oxidative and electrophilic stress response, mediates the expression and activation of EGFR in melanoma by elevating the levels of EGFR as well as its ligands EGF and TGFα. ChIP sequencing data show that NRF2 directly binds to the promoter of EGF, which contains a canonical antioxidant response element. Accordingly, EGF is induced by oxidative stress and is also increased in lung adenocarcinoma and head and neck carcinoma with mutationally activated NRF2. In contrast, regulation of EGFR and TGFA occurs by an indirect mechanism, which is enabled by the ability of NRF2 to block the activity of the melanocytic lineage factor MITF in melanoma. MITF effectively suppresses EGFR and TGFA expression and therefore serves as link between NRF2 and EGFR. As EGFR was previously described to stimulate NRF2 activity, the mutual activation of NRF2 and EGFR pathways was investigated. The presence of NRF2 was necessary for full EGFR pathway activation, as NRF2-knockout cells showed reduced AKT activation in response to EGF stimulation compared to controls. Conversely, EGF led to the nuclear localization and activation of NRF2, thereby demonstrating that NRF2 and EGFR are connected in a positive feedback loop in melanoma. In summary, our data show that the EGFR-positive melanoma phenotype is strongly supported by NRF2, thus revealing a novel maintenance mechanism for this clinically challenging melanoma subpopulation.

FAM129B-dependent activation of NRF2 promotes an invasive phenotype in BRAF mutant melanoma cells

Incidence of melanoma continues to rise in the United States with ~100,000 new cases diagnosed in 2019. While the 5-year survival rate of melanoma is 99% when localized, the rate of survival drops to 22.5% when distant disease is detected. As such, an area of great interest is understanding the mechanisms that promote melanoma metastasis so that better potential therapeutic targets can be discovered. Herein, we demonstrate that activation of NRF2 by FAM129B contributes to increased metastatic potential of BRAF V600E mutant melanoma cells. Specifically, FAM129B induces NRF2 by competing for Kelch-like ECH-associated protein 1 (KEAP1) binding (the negative regulator of NRF2) via an ETGE motif. Furthermore, we show that phosphorylation of FAM129B plays a role in mediating the interaction between FAM129B and KEAP1, as the phosphorylation status of FAM129B dictates its subcellular localization. When phosphorylated, FAM129B is found primarily in the cytosol where it can bind to KEAP1, but upon inhibition of mitogen-activated protein kinase kinase activity, FAM129B is localized to the cell membrane and no longer interacts with KEAP1. In BRAF V600E mutant melanoma, the mitogen-activated protein kinase pathway leads to hyperphosphorylation of FAM129B, and therefore FAM129B localizes to the cytosol, binds KEAP1, and upregulates NRF2. Importantly, genetic modulation or pharmacological inhibition that results in a decrease in FAM129B protein level or its phosphorylation decreases migration and invasion of mutant melanoma in an NRF2-dependent manner. Overall, these data indicate that phosphorylation of FAM129B plays a significant role in driving the metastatic potential of BRAF V600E melanoma via upregulation of the NRF2 signaling pathway.

Effect of stress-induced polyploidy on melanoma reprogramming and therapy resistance

Melanomas and their precursors, the melanocytes, are frequently exposed to UV due to their anatomic location, leading to DNA damage and reactive oxygen stress related harm. Such damage can result in multinucleation or polyploidy, in particularly in presence of mitotic or cell division failure. As a consequence, the cell encounters either of two fates: mitotic catastrophe, resulting in cell death, or survival and recovery, the latter occurring less frequently. However, when cells manage to recover in an polyploid state, they have often acquired new features, which allow them to tolerate and adapt to oncogene- or therapy induced stress. This review focuses on polyploidy inducers in melanoma and their effects on transcriptional reprogramming and phenotypic adaptation as well as the relevance of polyploid melanoma cells for therapy resistance.

Screening and identification of potential biomarkers and therapeutic drugs in melanoma via integrated bioinformatics analysis

Melanoma is a highly aggressive malignant skin tumor with a high rate of metastasis and mortality. In this study, a comprehensive bioinformatics analysis was used to clarify the hub genes and potential drugs. Download the GSE3189, GSE22301, and GSE35388 microarray datasets from the Gene Expression Omnibus (GEO), which contains a total of 33 normal samples and 67 melanoma samples. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) approach analyze DEGs based on the DAVID. Use STRING to construct protein-protein interaction network, and use MCODE and cytoHubba plug-ins in Cytoscape to perform module analysis and identified hub genes. Use Gene Expression Profile Interactive Analysis (GEPIA) to assess the prognosis of genes in tumors. Finally, use the Drug-Gene Interaction Database (DGIdb) to screen targeted drugs related to hub genes. A total of 140 overlapping DEGs were identified from the three microarray datasets, including 59 up-regulated DEGs and 81 down-regulated DEGs. GO enrichment analysis showed that these DEGs are mainly involved in the biological process such as positive regulation of gene expression, positive regulation of cell proliferation, positive regulation of MAP kinase activity, cell migration, and negative regulation of the apoptotic process. The cellular components are concentrated in the membrane, dendritic spine, the perinuclear region of cytoplasm, extracellular exosome, and membrane raft. Molecular functions include protein homodimerization activity, calmodulin-binding, transcription factor binding, protein binding, and cytoskeletal protein binding. KEGG pathway analysis shows that these DEGs are mainly related to protein digestion and absorption, PPAR signaling pathway, signaling pathways regulating stem cells' pluripotency, and Retinol metabolism. The 23 most closely related DEGs were identified from the PPI network and combined with the GEPIA prognostic analysis, CDH3, ESRP1, FGF2, GBP2, KCNN4, KIT, SEMA4D, and ZEB1 were selected as hub genes, which are considered to be associated with poor prognosis of melanoma closely related. Besides, ten related drugs that may have therapeutic effects on melanoma were also screened. These newly discovered genes and drugs provide new ideas for further research on melanoma.

NRF2 and the Ambiguous Consequences of Its Activation during Initiation and the Subsequent Stages of Tumourigenesis

NF-E2 p45-related factor 2 (NRF2, encoded in the human by NFE2L2) mediates short-term adaptation to thiol-reactive stressors. In normal cells, activation of NRF2 by a thiol-reactive stressor helps prevent, for a limited period of time, the initiation of cancer by chemical carcinogens through induction of genes encoding drug-metabolising enzymes. However, in many tumour types, NRF2 is permanently upregulated. In such cases, its overexpressed target genes support the promotion and progression of cancer by suppressing oxidative stress, because they constitutively increase the capacity to scavenge reactive oxygen species (ROS), and they support cell proliferation by increasing ribonucleotide synthesis, serine biosynthesis and autophagy. Herein, we describe cancer chemoprevention and the discovery of the essential role played by NRF2 in orchestrating protection against chemical carcinogenesis. We similarly describe the discoveries of somatic mutations in NFE2L2 and the gene encoding the principal NRF2 repressor, Kelch-like ECH-associated protein 1 (KEAP1) along with that encoding a component of the E3 ubiquitin-ligase complex Cullin 3 (CUL3), which result in permanent activation of NRF2, and the recognition that such mutations occur frequently in many types of cancer. Notably, mutations in NFE2L2, KEAP1 and CUL3 that cause persistent upregulation of NRF2 often co-exist with mutations that activate KRAS and the PI3K-PKB/Akt pathway, suggesting NRF2 supports growth of tumours in which KRAS or PKB/Akt are hyperactive. Besides somatic mutations, NRF2 activation in human tumours can occur by other means, such as alternative splicing that results in a NRF2 protein which lacks the KEAP1-binding domain or overexpression of other KEAP1-binding partners that compete with NRF2. Lastly, as NRF2 upregulation is associated with resistance to cancer chemotherapy and radiotherapy, we describe strategies that might be employed to suppress growth and overcome drug resistance in tumours with overactive NRF2.

NRF2-dependent stress defense in tumor antioxidant control and immune evasion

The transcription factor NRF2 is known as the master regulator of the oxidative stress response. Tumor entities presenting oncogenic activation of NRF2, such as lung adenocarcinoma, are associated with drug resistance, and accumulating evidence demonstrates its involvement in immune evasion. In other cancer types, the KEAP1/NRF2 pathway is not commonly mutated, but NRF2 is activated by other means such as radiation, oncogenic activity, cytokines, or other pro-oxidant triggers characteristic of the tumor niche. The obvious effect of stress-activated NRF2 is the protection from oxidative or electrophilic damage and the adaptation of the tumor metabolism to changing conditions. However, data from melanoma also reveal a role of NRF2 in modulating differentiation and suppressing anti-tumor immunity. This review summarizes the function of NRF2 in this tumor entity and discusses the implications for current tumor therapies.