Nrf2 in TIME: The Emerging Role of Nuclear Factor Erythroid 2-Related Factor 2 in the Tumor Immune Microenvironment

Molecular Targets of Oxidative Stress: Focus on Nuclear Factor Erythroid 2-Related Factor 2 Function in Leukemia and Other Cancers

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that plays a central role in regulating cellular responses to oxidative stress. It governs the expression of a broad range of genes involved in antioxidant defense, detoxification, metabolism, and other cytoprotective pathways. In normal cells, the transient activation of Nrf2 serves as a protective mechanism to maintain redox homeostasis. However, the persistent or aberrant activation of Nrf2 in cancer cells has been implicated in tumor progression, metabolic reprogramming, and resistance to chemotherapy and radiotherapy. These dual roles underscore the complexity of Nrf2 signaling and its potential as a therapeutic target. A deeper understanding of Nrf2 regulation in both normal and malignant contexts is essential for the development of effective Nrf2-targeted therapies. This review provides a comprehensive overview of Nrf2 regulation and function, highlighting its unique features in cancer biology, particularly its role in metabolic adaptation and drug resistance. Special attention is given to the current knowledge of Nrf2's involvement in leukemia and emerging strategies for its therapeutic modulation.

COX-2 Inhibition in Glioblastoma Cells Counteracts Resistance to Temozolomide by Inducing Oxidative Stress

Oxidative stress critically influences the pathophysiology of glioblastoma (GBM), a deadly and aggressive brain tumor. Reactive oxygen species (ROS) regulate cancer cell homeostasis, influencing the treatment response. The transcription factor Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) activates antioxidant defenses, protecting GBM cells from therapy-induced oxidative stress and contributing to Temozolomide (TMZ) resistance. Cyclooxygenase-2 (COX-2) plays a key role in GBM chemoresistance by modulating the tumor microenvironment and supporting a pro-survival phenotype. The impact of COX-2 inhibition by celecoxib (CXB), a selective COX-2 inhibitor, combined with TMZ on oxidative stress modulation linked to resistance was investigated in GBM primary cultures and cell lines. The drug combination CXB+TMZ was tested on TMZ-sensitive and -resistant cells, and ROS levels and Nrf2 activation were evaluated via a DCFH-DA probe and Western blotting, respectively. The oxidative stress marker malondialdehyde and antioxidant enzymes were assayed using standard methods. COX-2 inhibition combined with TMZ significantly increased ROS, while TMZ alone induced a compensatory antioxidant response, sustaining resistance. Drug combination reduced this response, restoring oxidative stress even in TMZ-resistant cells. Prostaglandin E2 reversed these effects, confirming the role of the COX-2/PGE2 axis in redox balance. Drug combination increased ROS, disrupted redox homeostasis and overcame TMZ resistance, supporting COX-2 inhibition as a promising GBM therapy strategy.

Oxidative Stress and Redox Imbalance: Common Mechanisms in Cancer Stem Cells and Neurodegenerative Diseases

Oxidative stress (OS) is an established hallmark of cancer and neurodegenerative disorders (NDDs), which contributes to genomic instability and neuronal loss. This review explores the contrasting role of OS in cancer stem cells (CSCs) and NDDs. Elevated levels of reactive oxygen species (ROS) contribute to genomic instability and promote tumor initiation and progression in CSCs, while in NDDs such as Alzheimer's and Parkinson's disease, OS accelerates neuronal death and impairs cellular repair mechanisms. Both scenarios involve disruption of the delicate balance between pro-oxidant and antioxidant systems, which leads to chronic oxidative stress. Notably, CSCs and neurons display alterations in redox-sensitive signaling pathways, including Nrf2 and NF-κB, which influence cell survival, proliferation, and differentiation. Mitochondrial dynamics further illustrate these differences: enhanced function in CSCs supports adaptability and survival, whereas impairments in neurons heighten vulnerability. Understanding these common mechanisms of OS-induced redox imbalance may provide insights for developing interventions, addressing aging hallmarks, and potentially mitigating or preventing both cancer and NDDs.

Multi-omics analysis revealed the novel role of NQO1 in microenvironment, prognosis and immunotherapy of hepatocellular carcinoma

NAD(P)H dehydrogenase quinone 1 (NQO1) is overexpressed in various cancers and is strongly associated with an immunosuppressive microenvironment and poor prognosis. In this study, we explored the role of NQO1 in the microenvironment, prognosis and immunotherapy of Hepatocellular carcinoma (HCC) using multi-omics analysis and machine learning. The results revealed that NQO1 was significantly overexpressed in HCC cells. NQO1+HCC cells were correlated with poor prognosis and facilitated tumor-associated macrophages (TAMs) polarization to M2 macrophages. We identified core NQO1-related genes (NRGs) and developed the NRGs-related risk-scores in hepatocellular carcinoma (NRSHC). The comprehensive nomogram integrating NRSHC, age, and pathological tumor-node-metastasis (pTNM) Stage achieved an area under the curve (AUC) above 0.7, demonstrating its accuracy in predicting survival outcomes and immunotherapy responses of HCC patients. High-risk patients exhibited worse prognoses but greater sensitivity to immunotherapy. Additionally, a web-based prediction tool was designed to enhance clinical utility. In conclusion, NQO1 may play a critical role in M2 polarization and accelerates HCC progression. The NRSHC model and accompanying tools offer valuable insights for personalized HCC treatment.

Parvimonas micra-polarized M2-like tumor-associated macrophages accelerate colorectal cancer development via IL-8 secretion

Parvimonas micra (Pm), a periodontal pathogen, has been implicated in the impairment of anti-tumor responses in colorectal cancer (CRC). The tumor microenvironment in CRC involves tumor-associated macrophages (TAMs), which are pivotal in modulating tumor-associated immune responses. The polarization of TAMs towards an M2-like phenotype promotes CRC progression by suppressing the immune system. However, the mechanisms by which Pm affects the progression of CRC remain inadequately elucidated. In this study, we explored the impact of Pm infection on CRC cell characteristics, including proliferation, chemoresistance, migration, and macrophage polarization. We found that Pm-infected THP-1-derived macrophages exhibited elevated interleukin-10 levels, a well-established M2 marker. Conditioned media from Pm-treated THP-1 cells significantly enhanced CRC cell proliferation, cisplatin resistance, and migration, and interleukin-8 was identified as a key factor. Consistent with the in vitro results, an azoxymethane/dextran sodium sulfate mouse model treated with oral Pm showed accelerated CRC tumor growth. These results offer mechanistic insights into the influence of Pm infection on tumor microenvironment in CRC through M2-like macrophage polarization. The identified pathways may serve as potential targets for therapeutic interventions for CRC.

Structure, unique biological properties, and mechanisms of action of transforming growth factor β

Transforming growth factor β (TGF-β) is a ubiquitous molecule that is extremely conserved structurally and plays a systemic role in human organism. TGF-β is a homodimeric molecule consisting of two subunits joined through a disulphide bond. In mammals, three genes code for TGF-β1, TGF-β2, and TGF-β3 isoforms of this cytokine with a dominating expression of TGF-β1. Virtually, all normal cells contain TGF-β and its specific receptors. Considering the exceptional role of fine balance played by the TGF-β in anumber of physiological and pathological processes in human body, this cytokine may be proposed for use in medicine as an immunosuppressant in transplantology, wound healing and bone repair. TGFb itself is an important target in oncology. Strategies for blocking members of TGF-β signaling pathway as therapeutic targets have been considered. In this review, signalling mechanisms of TGF-β1 action are addressed, and their role in physiology and pathology with main focus on carcinogenesis are described.

Metabolic remodeling in cancer and senescence and its therapeutic implications

Cellular metabolism is a flexible and plastic network that often dictates physiological and pathological states of the cell, including differentiation, cancer, and aging. Recent advances in cancer metabolism represent a tremendous opportunity to treat cancer by targeting its altered metabolism. Interestingly, despite their stable growth arrest, senescent cells - a critical component of the aging process - undergo metabolic changes similar to cancer metabolism. A deeper understanding of the similarities and differences between these disparate pathological conditions will help identify which metabolic reprogramming is most relevant to the therapeutic liabilities of senescence. Here, we compare and contrast cancer and senescence metabolism and discuss how metabolic therapies can be established as a new modality of senotherapy for healthy aging.

Development of Potential Therapeutic Agents from Black Elderberries (the Fruits of Sambucus nigra L.)

Elderberry (Sambucus nigra L.) is a widespread deciduous shrub, of which the fruits (elderberries) are used in the food industry to produce different types of dietary supplement products. These berries have been found to show multiple bioactivities, including antidiabetic, anti-infective, antineoplastic, anti-obesity, and antioxidant activities. An elderberry extract product, Sambucol®, has also been used clinically for the treatment of viral respiratory infections. As the major components, phenolic compounds, such as simple phenolic acids, anthocyanins and other flavonoids, and tannins, show promising pharmacological effects that could account for the bioactivities observed for elderberries. Based on these components, salicylic acid and its acetate derivative, aspirin, have long been used for the treatment of different disorders. Dapagliflozin, an FDA-approved antidiabetic drug, has been developed based on the conclusions obtained from a structure-activity relationship study for a simple hydrolyzable tannin, β-pentagalloylglucoside (β-PGG). Thus, the present review focuses on the development of therapeutic agents from elderberries and their small-molecule secondary metabolites. It is hoped that this contribution will support future investigations on elderberries.

Reprogramming of tumor-associated macrophages by metabolites generated from tumor microenvironment

The tumor microenvironment comprises both tumor and non-tumor stromal cells, including tumor-associated macrophages (TAMs), endothelial cells, and carcinoma-associated fibroblasts. TAMs, major components of non-tumor stromal cells, play a crucial role in creating an immunosuppressive environment by releasing cytokines, chemokines, growth factors, and immune checkpoint proteins that inhibit T cell activity. During tumors develop, cancer cells release various mediators, including chemokines and metabolites, that recruit monocytes to infiltrate tumor tissues and subsequently induce an M2-like phenotype and tumor-promoting properties. Metabolites are often overlooked as metabolic waste or detoxification products but may contribute to TAM polarization. Furthermore, macrophages display a high degree of plasticity among immune cells in the tumor microenvironment, enabling them to either inhibit or facilitate cancer progression. Therefore, TAM-targeting has emerged as a promising strategy in tumor immunotherapy. This review provides an overview of multiple representative metabolites involved in TAM phenotypes, focusing on their role in pro-tumoral polarization of M2.

The kynurenine pathway presents multi-faceted metabolic vulnerabilities in cancer

The kynurenine pathway (KP) and associated catabolites play key roles in promoting tumor progression and modulating the host anti-tumor immune response. To date, considerable focus has been on the role of indoleamine 2,3-dioxygenase 1 (IDO1) and its catabolite, kynurenine (Kyn). However, increasing evidence has demonstrated that downstream KP enzymes and their associated metabolite products can also elicit tumor-microenvironment immune suppression. These advancements in our understanding of the tumor promotive role of the KP have led to the conception of novel therapeutic strategies to target the KP pathway for anti-cancer effects and reversal of immune escape. This review aims to 1) highlight the known biological functions of key enzymes in the KP, and 2) provide a comprehensive overview of existing and emerging therapies aimed at targeting discrete enzymes in the KP for anti-cancer treatment.

Vincamine, from an antioxidant and a cerebral vasodilator to its anticancer potential

Vincamine is a naturally occurring indole alkaloid showing antioxidant activity and has been used clinically for the prevention and treatment of cerebrovascular disorders and insufficiencies. It has been well documented that antioxidants may contribute to cancer treatment, and thus, vincamine has been investigated recently for its potential antitumor activity. Vincamine was found to show cancer cell cytotoxicity and to modulate several important proteins involved in tumor growth, including acetylcholinesterase (AChE), mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), and T-box 3 (TBX3). Several bisindole alkaloids, including vinblastine and vincristine and their synthetic derivatives, vindesine, vinflunine, and vinorelbine, have been used as clinically effective cancer chemotherapeutic agents. In the present review, the discovery and development of vincamine as a useful therapeutic agent and its antioxidant and antitumor activity are summarized, with its antioxidant-related mechanisms of anticancer potential being described. Also, discussed herein are the design of the potential vincamine-based oncolytic agents, which could contribute to the discovery of further new agents for cancer treatment.

Medicinal Chemistry Insights into the Development of Small-Molecule Kelch-Like ECH-Associated Protein 1-Nuclear Factor Erythroid 2-Related Factor 2 (Keap1-Nrf2) Protein-Protein Interaction Inhibitors

Oxidative stress has been implicated in a wide range of pathological conditions. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) exerts a central role in regulating the cellular defense system against oxidative and electrophilic insults. Nonelectrophilic inhibition of the protein-protein interaction (PPI) between Kelch-like ECH-associated protein 1 (Keap1) and Nrf2 has become a promising approach to activate Nrf2. Recently, multiple drug discovery strategies have facilitated the development of small-molecule Keap1-Nrf2 PPI inhibitors with potent activity and favorable drug-like properties. In this Perspective, we summarize the latest progress of small-molecule Keap1-Nrf2 PPI inhibitors from medicinal chemistry insights and discuss future prospects and challenges in this field.

Macrophage Nrf 2 the rescue

The exuberant phagocytosis of apoptotic cell corpses by macrophages in Drosophila embryos creates highly oxidative environments. Stow and Sweet discuss work from Clemente and Weavers (2023. J. Cell Biol.https://doi.org/10.1083/jcb.202203062) showing for the first time how macrophage Nrf2 is primed to help sustain immune function and mitigate bystander oxidative damage.