Nrf2 Mediates Metabolic Reprogramming in Non-Small Cell Lung Cancer

A detailed insight into macrophages' role in shaping lung carcinogenesis

Despite significant advancements in cancer treatment in recent decades, the high mortality rate associated with lung cancer remains a significant concern. The development and proper execution of new targeted therapies needs more deep knowledge regarding the lung cancer associated tumour microenvironment. One of the key component of that tumour microenvironment is the lung resident macrophages. Although in normal physiological condition the lung resident macrophages are believed to maintain lung homeostasis, but they may also initiate a vicious inflammatory response in abnormal conditions which is linked to lung cancer development. Depending on the activation pathway, the lung resident macrophages are either of M1 or M2 sub-type. The M1 and M2 sub-types differ significantly in various prospectuses, from phenotypic markers to metabolic pathways. In addition to this generalized classification, the recent advancement of the multiomics technology is able to identify some other sub-types of lung resident macrophages. Researchers have also observed that these different sub-types can manipulate the pathogenesis of lung carcinogenesis in a context dependent manner and can either promote or inhibit the development of lung carcinogenesis upon receiving proper activation. As proper knowledge about the role played by the lung resident macrophages' in shaping the lung carcinogenesis is limited, so the main purpose of this review is to bring all the available information under the same roof. We also elaborated the different mechanisms involved in maintenance of the plasticity of M1/M2 sub-type, as this plasticity can be a good target for lung cancer treatment.

Luteolin as a potential therapeutic candidate for lung cancer: Emerging preclinical evidence

Lung cancer is a prevalent malignant tumor and a leading cause of cancer-related fatalities globally. However, current treatments all have limitations. Therefore, there is an urgent need to identify a readily available therapeutic agent to counteract lung cancer development and progression. Luteolin is a flavonoid derived from vegetables and herbs that possesses preventive and therapeutic effects on various cancers. With the goal of providing new directions for the treatment of lung cancer, we review here the recent findings on luteolin so as to provide new ideas for the development of new anti-lung cancer drugs. The search focused on studies published between January 1995 and January 2024 that explored the use of luteolin in lung cancer. A comprehensive literature search was conducted in the SCOPUS, Google Scholar, PubMed, and Web of Science databases using the keywords "luteolin" and "lung cancer." By collecting previous literature, we found that luteolin has multiple mechanisms of therapeutic effects, including promotion of apoptosis in lung cancer cells; inhibition of tumor cell proliferation, invasion and metastasis; and modulation of immune responses. In addition, it can be used as an adjuvant to radio-chemotherapy and helps to ameliorate cancer complications. This review summarizes the structure, natural sources, physicochemical properties and pharmacokinetics of luteolin, and focuses on the anti-lung cancer mechanism of luteolin, so as to provide new ideas for the development of new anti-lung cancer drugs.

Nuclear Factor Erythroid 2 Related Factor 2 and Mitochondria Form a Mutually Regulating Circuit in the Prevention and Treatment of Metabolic Syndrome

Significance: Metabolic syndrome (MetS) has become a major global public health problem and there is an urgent need to elucidate its pathogenesis and find more effective targets and modalities for intervention. Recent Advances: Oxidative stress and inflammation are two of the major causes of MetS-related symptoms such as insulin resistance and obesity. Nuclear factor erythroid 2 related factor 2 (Nrf2) is one of the important systems responding to oxidative stress and inflammation. As cells undergo stress, cysteines within Kelch-like ECH-associated protein 1 (Keap1) are oxidized or electrophilically modified, allowing Nrf2 to escape ubiquitination and be translocated from the cytoplasm to the nucleus, facilitating the initiation of the antioxidant transcriptional program. Meanwhile, a growing body of evidence points out a specific modulation of mitochondrial homeostasis by Nrf2. After nuclear translocation, Nrf2 activates downstream genes involved in various aspects of mitochondrial homeostasis, including mitochondrial biogenesis and dynamics, mitophagy, aerobic respiration, and energy metabolism. In turn, mitochondria reciprocally activate Nrf2 by releasing reactive oxygen species and regulating antioxidant enzymes. Critical Issues: In this review, we first summarize the interactions between Nrf2 and mitochondria in the modulation of oxidative stress and inflammation to ameliorate MetS, then propose that Nrf2 and mitochondria form a mutually regulating circuit critical to maintaining homeostasis during MetS. Future Directions: Targeting the Nrf2-mitochondrial circuit may be a promising strategy to ameliorate MetS, such as obesity, diabetes, and cardiovascular diseases.

Antioxidant effect of lactic acid bacteria in human bronchial epithelial cells exposed to cigarette smoke

AIMS

Chronic lung diseases are a major and increasing global health problem, commonly caused by cigarette smoke. We aimed to explore the antioxidant effects of lactic acid bacteria (LAB) against cigarette smoke in bronchial epithelial cells.

METHODS AND RESULTS

The antioxidant effects of 21 heat-killed (HK) LAB strains were tested in cigarette smoke-stimulated BEAS-2B cells and 3-D bronchospheres organoids. We showed that HK Lactiplantibacillus plantarum BGPKM22 possesses antioxidant activity against cigarette smoke, resistance to hydrogen peroxide, and free radical neutralizing activity. We demonstrated that HK BGPKM22 inhibited cigarette smoke-induced expression of the Aryl hydrocarbon receptor (AhR) and Nuclear factor erythroid 2 related factor 2 (Nrf2) genes. The cell-free supernatant (SN) of BGPKM22 fully confirmed the effects of HK BGPKM22.

CONCLUSIONS

For the first time, we revealed that HK and SN of Lactip. plantarum BGPKM22 possess antioxidant activity and modulate AhR and Nrf2 gene expression in bronchial epithelial cells exposed to cigarette smoke.

Metabolic barriers in non-small cell lung cancer with LKB1 and/or KEAP1 mutations for immunotherapeutic strategies

Currently, immune checkpoint inhibitors (ICIs) are widely considered the standard initial treatment for advanced non-small cell lung cancer (NSCLC) when there are no targetable driver oncogenic alternations. NSCLC tumors that have two alterations in tumor suppressor genes, such as liver kinase B1 (LKB1) and/or Kelch-like ECH-associated protein 1 (KEAP1), have been found to exhibit reduced responsiveness to these therapeutic strategies, as revealed by multiomics analyses identifying immunosuppressed phenotypes. Recent advancements in various biological approaches have gradually unveiled the molecular mechanisms underlying intrinsic reprogrammed metabolism in tumor cells, which contribute to the evasion of immune responses by the tumor. Notably, metabolic alterations in glycolysis and glutaminolysis have a significant impact on tumor aggressiveness and the remodeling of the tumor microenvironment. Since glucose and glutamine are essential for the proliferation and activation of effector T cells, heightened consumption of these nutrients by tumor cells results in immunosuppression and resistance to ICI therapies. This review provides a comprehensive summary of the clinical efficacies of current therapeutic strategies against NSCLC harboring LKB1 and/or KEAP1 mutations, along with the metabolic alterations in glycolysis and glutaminolysis observed in these cancer cells. Furthermore, ongoing trials targeting these metabolic alterations are discussed as potential approaches to overcome the extremely poor prognosis associated with this type of cancer.

Targeting Cell Signaling Pathways in Lung Cancer by Bioactive Phytocompounds

Lung cancer is a heterogeneous group of malignancies with high incidence worldwide. It is the most frequently occurring cancer in men and the second most common in women. Due to its frequent diagnosis and variable response to treatment, lung cancer was reported as the top cause of cancer-related deaths worldwide in 2020. Many aberrant signaling cascades are implicated in the pathogenesis of lung cancer, including those involved in apoptosis (B cell lymphoma protein, Bcl-2-associated X protein, first apoptosis signal ligand), growth inhibition (tumor suppressor protein or gene and serine/threonine kinase 11), and growth promotion (epidermal growth factor receptor/proto-oncogenes/phosphatidylinositol-3 kinase). Accordingly, these pathways and their signaling molecules have become promising targets for chemopreventive and chemotherapeutic agents. Recent research provides compelling evidence for the use of plant-based compounds, known collectively as phytochemicals, as anticancer agents. This review discusses major contributing signaling pathways involved in the pathophysiology of lung cancer, as well as currently available treatments and prospective drug candidates. The anticancer potential of naturally occurring bioactive compounds in the context of lung cancer is also discussed, with critical analysis of their mechanistic actions presented by preclinical and clinical studies.

Histone deacetylase inhibitor belinostat regulates metabolic reprogramming in killing KRAS-mutant human lung cancer cells

Kirsten rat sarcoma virus (KRAS) oncogene, found in 20%-25% of lung cancer patients, potentially regulates metabolic reprogramming and redox status during tumorigenesis. Histone deacetylase (HDAC) inhibitors have been investigated for treating KRAS-mutant lung cancer. In the current study, we investigate the effect of HDAC inhibitor (HDACi) belinostat at clinically relevant concentration on nuclear factor erythroid 2-related factor 2 (NRF2) and mitochondrial metabolism for the treatment of KRAS-mutant human lung cancer. LC-MS metabolomic study of belinostat on mitochondrial metabolism was performed in G12C KRAS-mutant H358 non-small cell lung cancer cells. Furthermore, l-methionine (methyl-13 C) isotope tracer was used to explore the effect of belinostat on one-carbon metabolism. Bioinformatic analyses of metabolomic data were performed to identify the pattern of significantly regulated metabolites. To study the effect of belinostat on redox signaling ARE-NRF2 pathway, luciferase reporter activity assay was done in stably transfected HepG2-C8 cells (containing pARE-TI-luciferase construct), followed by qPCR analysis of NRF2 and its target gene in H358 cells, which was further confirmed in G12S KRAS-mutant A549 cells. Metabolomic study reveals significantly altered metabolites related to redox homeostasis, including tricarboxylic acid (TCA) cycle metabolites (citrate, aconitate, fumarate, malate, and α-ketoglutarate); urea cycle metabolites (Arginine, ornithine, argino-succinate, aspartate, and fumarate); and antioxidative glutathione metabolism pathway (GSH/GSSG and NAD/NADH ratio) after belinostat treatment. 13 C stable isotope labeling data indicates potential role of belinostat in creatine biosynthesis via methylation of guanidinoacetate. Moreover, belinostat downregulated the expression of NRF2 and its target gene NAD(P)H:quinone oxidoreductase 1 (NQO1), indicating anticancer effect of belinostat is mediated, potentially via Nrf2-regulated glutathione pathway. Another HDACi panobinostat also showed potential anticancer effect in both H358 and A549 cells via Nrf2 pathway. In summary, belinostat is effective in killing KRAS-mutant human lung cancer cells by regulating mitochondrial metabolism which could be used as biomarkers for preclinical and clinical studies.

Targeting reactive oxygen species and fat acid oxidation for the modulation of tumor-associated macrophages: a narrative review

Tumor-associated macrophages (TAMs) are significant immunocytes infiltrating the tumor microenvironment(TME). Recent research has shown that TAMs exhibit diversity in terms of their phenotype, function, time, and spatial distribution, which allows for further classification of TAM subtypes. The metabolic efficiency of fatty acid oxidation (FAO) varies among TAM subtypes. FAO is closely linked to the production of reactive oxygen species (ROS), which play a role in processes such as oxidative stress. Current evidence demonstrates that FAO and ROS can influence TAMs' recruitment, polarization, and phagocytosis ability either individually or in combination, thereby impacting tumor progression. But the specific mechanisms associated with these relationships still require further investigation. We will review the current status of research on the relationship between TAMs and tumor development from three aspects: ROS and TAMs, FAO and TAMs, and the interconnectedness of FAO, ROS, and TAMs.

Bioactivity-guided fractionation of Helicteres angustifolia L. extract and its molecular evidence for tumor suppression

Helicteres angustifolia L. (Helicteres angustifolia) has been commonly used in folk medicine to treat cancer; however, its mechanisms of action remain obscure. In our earlier work, we reported that aqueous extract of H. angustifolia root (AQHAR) possesses attractive anticancer properties. In the present study, we isolated five ethanol fractions from AQHAR and investigated their therapeutic efficacy in human non-small cell lung cancer (NSCLC) cells. The results showed that among the five fractions, the 40% ethanol fraction (EF40) containing multiple bioactive compounds exhibited the best selective killing effect on NSCLC cells with no obvious toxicity to normal human fibroblasts. Mechanistically, EF40 reduced the expression of nuclear factor-E2-related factor 2 (Nrf2), which is constitutively expressed at high levels in many types of cancers. As a result, Nrf2-dependent cellular defense responses are suppressed, leading to the intracellular accumulation of reactive oxygen species (ROS). Extensive biochemical analyses revealed that EF40 caused cell cycle arrest and apoptosis through activation of the ROS-mediated DNA damage response. Furthermore, treatment with EF40 compromised NSCLC cell migration, as evidenced by the downregulation of matrix metalloproteinases (MMPs) and heterogeneous nuclear ribonucleoprotein K (hnRNP-K). In vivo studies using A549 xenografts in nude mice also revealed significant suppression of tumor growth and lung metastasis in the treated group. We propose that EF40 may serve as a potential natural anti-NSCLC drug that warrants further mechanistic and clinical attention.

Distinct Nrf2 Signaling Thresholds Mediate Lung Tumor Initiation and Progression

Mutations in the KEAP1-NRF2 (Kelch-like ECH-associated protein 1-nuclear factor-erythroid 2 p45-related factor 2) pathway occur in up to a third of non-small cell lung cancer (NSCLC) cases and often confer resistance to therapy and poor outcomes. Here, we developed murine alleles of the KEAP1 and NRF2 mutations found in human NSCLC and comprehensively interrogated their impact on tumor initiation and progression. Chronic NRF2 stabilization by Keap1 or Nrf2 mutation was not sufficient to induce tumorigenesis, even in the absence of tumor suppressors, p53 or LKB1. When combined with KrasG12D/+, constitutive NRF2 activation promoted lung tumor initiation and early progression of hyperplasia to low-grade tumors but impaired their progression to advanced-grade tumors, which was reversed by NRF2 deletion. Finally, NRF2 overexpression in KEAP1 mutant human NSCLC cell lines was detrimental to cell proliferation, viability, and anchorage-independent colony formation. Collectively, these results establish the context-dependence and activity threshold for NRF2 during the lung tumorigenic process.

SIGNIFICANCE

Stabilization of the transcription factor NRF2 promotes oncogene-driven tumor initiation but blocks tumor progression, indicating distinct, threshold-dependent effects of the KEAP1/NRF2 pathway in different stages of lung tumorigenesis.

Cancer Cell-Intrinsic Alterations Associated with an Immunosuppressive Tumor Microenvironment and Resistance to Immunotherapy in Lung Cancer

Despite the great clinical success of immunotherapy in lung cancer patients, only a small percentage of them (<40%) will benefit from this therapy alone or combined with other strategies. Cancer cell-intrinsic and cell-extrinsic mechanisms have been associated with a lack of response to immunotherapy. The present study is focused on cancer cell-intrinsic genetic, epigenetic, transcriptomic and metabolic alterations that reshape the tumor microenvironment (TME) and determine response or refractoriness to immune checkpoint inhibitors (ICIs). Mutations in KRAS, SKT11(LKB1), KEAP1 and TP53 and co-mutations of these genes are the main determinants of ICI response in non-small-cell lung cancer (NSCLC) patients. Recent insights into metabolic changes in cancer cells that impose restrictions on cytotoxic T cells and the efficacy of ICIs indicate that targeting such metabolic restrictions may favor therapeutic responses. Other emerging pathways for therapeutic interventions include epigenetic modulators and DNA damage repair (DDR) pathways, especially in small-cell lung cancer (SCLC). Therefore, the many potential pathways for enhancing the effect of ICIs suggest that, in a few years, we will have much more personalized medicine for lung cancer patients treated with immunotherapy. Such strategies could include vaccines and chimeric antigen receptor (CAR) cells.

Natural Compounds, Optimal Combination of Brusatol and Polydatin Promote Anti-Tumor Effect in Breast Cancer by Targeting Nrf2 Signaling Pathway

Triple-negative breast cancer (TNBC) has been clearly recognized as a heterogeneous tumor with the worst prognosis among the subtypes of breast cancer (BC). The advent and application of current small-molecule drugs for treating TNBC, as well as other novel inhibitors, among others, have made treatment options for TNBC more selective. However, there are still problems, such as poor patient tolerance, large administration doses, high dosing frequency, and toxic side effects, necessitating the development of more efficient and less toxic treatment strategies. High expression of Nrf2, a vital antioxidant transcription factor, often promotes tumor progression, and it is also one of the most effective targets in BC therapy. We found that in MDA-MB-231 cells and SUM159 cells, brusatol (BRU) combined with polydatin (PD) could significantly inhibit cell proliferation in vitro, significantly downregulate the expression of Nrf2 protein as well as the expression of downstream related target genes Heme Oxygenase-1 (HO-1) and NAD(P)H dehydrogenase, quinone 1 (NQO1), and promote reactive oxygen species (ROS) levels to further strengthen the anti-tumor effect. Furthermore, we discovered in our in vivo experiments that by reducing the drug dosage three times, we could significantly reduce tumor cell growth while avoiding toxic side effects, providing a treatment method with greater clinical application value for TNBC treatment.

Role of ionizing radiation activated NRF2 in lung cancer radioresistance

Radiotherapies are commonly used to target remaining tumor niches after surgery of solid tumors but are restricted due to therapeutic resistance. Several pathways of radioresistance have been reported in various cancers. This study investigates the pivotal role of Nuclear factor-erythroid 2-related factor 2 (NRF2) in the activation of DNA damage repair in lung cancer cells after x-rays exposure. To explore the NRF2 activation after ionizing irradiations, this study uses a knockdown of NRF2, which shows potential DNA damage after x-rays irradiation in lung cancers. This work further shows that NRF2 knockdown disrupts damaged DNA repair by inhibiting DNA-dependent protein kinase catalytic subunit. At the same time, NRF2 knockdown by shRNA considerably disparate homologous recombination by interfering with Rad51 expression. Further investigation of the associated pathway reveals that NRF2 activation mediates DNA damage response via the mitogen-activated protein kinase (MAPK) pathway as the knockout of NRF2 directly enhances intracellular MAPK phosphorylation. Similarly, both NAC and constitutive knockout of NRF2 disrupt DNA-dependent protein kinase catalytic subunit, while NRF2 knockout failed to upregulate Rad51 expression after irradiation in-vivo. Taken together, these findings advocate NRF2 plays a critical role in the development of radioresistance by upregulating DNA damage response via the MAPK pathway, which can be of great significance.

Oncology Care in Non-Small Cell Lung Cancer-Personalizing the Treatment Plan

With potentially curative targeted and immunotherapies for non-small cell lung cancer, long term survival of at least 5 to 10 years is increasingly possible. A personalized, holistic, and multidisciplinary home healthcare treatment plan can help cancer patients transition from acute to chronic disease management. Factors to be considered include the patient's goals, treatment-related risks, the degree of metastasis, acute symptom management needs, and the desire and ability to participate in the treatment plan. The case history illustrates how genetic sequencing and immunohistochemistry testing guide treatment decisions. Strategies for pharmacological and nonpharmacological management of acute pain related to pathological spinal fractures are discussed. Care coordination that includes the patient, home care nurses and therapists, the oncologist, and the oncology nurse navigator is essential to transition the patient with advanced metastatic cancer to the highest possible functional status and quality of life. Discharge teaching should include early recognition and intervention for adverse effects of medications and signs or symptoms that may signal disease reoccurrence. The use of a written, patient-driven survivorship plan is important to assure diagnostic and treatment information is summarized, follow-up tests and scans are scheduled, and screening tests for other types of cancer are included.

Benzo[a]pyrene treatment modulates Nrf2/Keap1 axis and changes the metabolic profile in rat lung cancer

Lung cancer is an aggressive malignancy and the leading cause of cancer-related deaths. Benzo[a]pyrene (B[a]P), a polycyclic hydrocarbon, plays a pivotal role in lung carcinogenesis. Uncovering the molecular mechanism underlying the pathophysiology of B[a]P induced malignancy is crucial. Male Sprague Dawley rats were induced with B[a]P to generate a lung cancer model. The B[a]P administered rats show increased body and lung weight, loss of normal pulmonary architecture, and decreased survival. This study demonstrated that B[a]P upregulates activating transcription factor-6 (ATF6) and C/EBP Homologous Protein (CHOP) and induces endoplasmic reticulum (ER) stress. B[a]P also dysregulated mitochondrial homeostasis by upregulating, PTEN-induced putative kinase-1 (PINK1) and Parkin. B[a]P affected the levels of superoxide dismutase (SOD), reduced glutathione (GSH), malondialdehyde (MDA), and increased oxidative stress. B[a]P exposure downregulated Kelch-like ECH-associated protein 1 (Keap1) and upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) and Heme oxygenase-1(HO1). The metabolomic study identified that biosynthesis of nucleotide, amino acids, pentose phosphate pathway (PPP), tricarboxylic acid cycle (TCA), and glutathione metabolism were up-accumulated. On the other hand, lower accumulation of fatty acids e.g., palmitic acid, stearic acid, and oleic acid were reported in the B[a]P induced group. Overall, the results of this study indicate that B[a]P treatment affects several signaling and metabolic pathways, whose dysregulation might be involved in lung cancer induction.

Dual role of Nrf2 in cancer: molecular mechanisms, cellular functions and therapeutic interventions

BACKGROUND

Nrf2 regulates oxidative stress, which is essential for cellular function. Fundamental initiation of Nrf2 in many malignancies increases prosurvival genes & endorses tumour cell propagation via metabolic reprogramming, suppression of tumour programmed cell death, & increased cancer stem cell self-renewal potential. More specifically, Nrf2 has been associated with cancer cell chemoresistance, radioresistance & inflammation-induced carcinogenesis.  METHODS AND RESULTS: Many Nrf2 inhibitors have been revealed for tumour treatment and targeting Nrf2 could be an effective cancer therapeutic method. Before spreading, cancer cells adapt to their surroundings. Cancer cells usually have mutations in tumor suppressor genes. In a variety of malignancies, somatic mutations & other anomalies in the Nrf2 genes, as well as renowned cancer suppressor genes including TP53, CDKN2A, PTEN & PIK3CA, have been found. In tumour cells, somatic mutations in the Nrf2 genes, as well as additional mechanisms that affect Nrf2 binding, and produce aberrant Nrf2 activation. Uncontrolled Nrf2 causes tumour cells to become resistant to antineoplastic drugs & reactive oxygen species (ROS), as well as guiding them toward metabolic reprogramming.  CONCLUSIONS: As a result, Nrf2 has been studied as potential malignancy treatment target. We covered the pathways, mechanisms, and dual characteristics of Nrf2 in malignancy in this article. We also discussed how Nrf2 inhibitors are targeted against cancer in this review.

Metabolic targeting, immunotherapy and radiation in locally advanced non-small cell lung cancer: Where do we go from here?

In the US, there are ~250,000 new lung cancer diagnoses and ~130,000 deaths per year, and worldwide there are an estimated 1.6 million deaths per year from this deadly disease. Lung cancer is the most common cause of cancer death worldwide, and it accounts for roughly a quarter of all cancer deaths in the US. Non-small cell lung cancer (NSCLC) represents 80-85% of these cases. Due to an enormous tobacco cessation effort, NSCLC rates in the US are decreasing, and the implementation of lung cancer screening guidelines and other programs have resulted in a higher percentage of patients presenting with potentially curable locoregional disease, instead of distant disease. Exciting developments in molecular targeted therapy and immunotherapy have resulted in dramatic improvement in patients' survival, in combination with new surgical, pathological, radiographical, and radiation techniques. Concurrent platinum-based doublet chemoradiation therapy followed by immunotherapy has set the benchmark for survival in these patients. However, despite these advances, ~50% of patients diagnosed with locally advanced NSCLC (LA-NSCLC) survive long-term. In patients with local and/or locoregional disease, chemoradiation is a critical component of curative therapy. However, there remains a significant clinical gap in improving the efficacy of this combined therapy, and the development of non-overlapping treatment approaches to improve treatment outcomes is needed. One potential promising avenue of research is targeting cancer metabolism. In this review, we will initially provide a brief general overview of tumor metabolism as it relates to therapeutic targeting. We will then focus on the intersection of metabolism on both oxidative stress and anti-tumor immunity. This will be followed by discussion of both tumor- and patient-specific opportunities for metabolic targeting in NSCLC. We will then conclude with a discussion of additional agents currently in development that may be advantageous to combine with chemo-immuno-radiation in NSCLC.

The current status and future prospects for therapeutic targeting of KEAP1-NRF2 and β-TrCP-NRF2 interactions in cancer chemoresistance

Drug resistance is one of the biggest challenges in cancer treatment and limits the potential to cure patients. In many tumors, sustained activation of the protein NRF2 makes tumor cells resistant to chemo- and radiotherapy. Thus, blocking inappropriate NRF2 activity in cancers has been shown to reduce resistance in models of the disease. There is a growing scientific interest in NRF2 inhibitors. However, the compounds developed so far are not target-specific and are associated with a high degree of toxicity, hampering clinical applications. Compounds that can enhance the binding of NRF2 to its ubiquitination-facilitating regulator proteins, either KEAP1 or β-TrCP, have the potential to increase NRF2 degradation and may be of value as potential chemosensitising agents in cancer treatment. Approaches based on molecular glue-type mechanisms, in which ligands stabilise a ternary complex between a protein and its binding partner have shown to enhance β-catenin degradation by stabilising its interaction with β-TrCP. This strategy could be applied to rationally discover degradative β-TrCP-NRF2 and KEAP1-NRF2 protein-protein interaction enhancers. We are proposing a novel approach to selectively suppress NRF2 activity in tumors. It is based on recent methodology and has the potential to be a promising new addition to the arsenal of anticancer agents.

Targeting mitochondria in cancer therapy: Insight into photodynamic and photothermal therapies

Mitochondria are critical multifunctional organelles in cells that generate power, produce reactive oxygen species, and regulate cell survival. Mitochondria that are dysfunctional are eliminated via mitophagy as a way to protect cells under moderate stress and physiological conditions. However, mitophagy is a double-edged sword and can trigger cell death under severe stresses. By targeting mitochondria, photodynamic (PD) and photothermal (PT) therapies may play a role in treating cancer. These therapeutic modalities alter mitochondrial membrane potential, thereby affecting respiratory chain function and generation of reactive oxygen species promotes signaling pathways for cell death. In this regard, PDT, PTT, various mitochondrion-targeting agents and therapeutic methods could have exploited the vital role of mitochondria as the doorway to regulated cell death. Targeted mitochondrial therapies would provide an excellent opportunity for effective mitochondrial injury and accurate tumor erosion. Herein, we summarize the recent progress on the roles of PD and PT treatments in regulating cancerous cell death in relation to mitochondrial targeting and the signaling pathways involved.

The MARCHF6 E3 ubiquitin ligase acts as an NADPH sensor for the regulation of ferroptosis

Ferroptosis is a unique form of cell death caused by excessive iron-dependent lipid peroxidation. The level of the anabolic reductant NADPH is a biomarker of ferroptosis sensitivity. However, specific regulators that detect cellular NADPH levels, thereby modulating downstream ferroptosis cascades, are largely unknown. We show here that the transmembrane endoplasmic reticulum MARCHF6 E3 ubiquitin ligase recognizes NADPH through its C-terminal regulatory region. This interaction upregulates the E3 ligase activity of MARCHF6, thus downregulating ferroptosis. We also found that MARCHF6 mediates the degradation of the key ferroptosis effectors ACSL4 and p53. Furthermore, inhibiting ferroptosis rescued the growth of MARCHF6-deficient tumours and peri-natal lethality of Marchf6^-/- mice. Together, these findings identify MARCHF6 as a previously unknown NADPH sensor in the ubiquitin system and a crucial regulator of ferroptosis.

State-of-the-art combination treatment strategies for advanced stage non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the most abundant type of epithelial lung cancer being diagnosed after 40% of invasions of excrescence in pulmonary tissues. According to WHO, 30% of NSCLC patients can be cured if diagnosed and treated early. Mutations play an important role in advanced stage NSCLC treatment, which includes critical proteins necessary for cellular growth and replication. Restricting such mutations may improve survival in lung cancer patients. Newer technologies include endoscopic bronchial ultrasonography and esophageal ultrasonography. Currently, policymaking or decision-making for treatment regimens merely depends on the genomic alterations and mutations. DNA sequencing, methylation, protein, and fragmented DNA analysis do NSCLC screening. Achievement of these goals requires consideration of available therapeutics in current anticancer approaches for improving quality of life and treatment outcomes for NSCLC patient. The specific goals of this review are to discuss first-line and second-line therapies for advanced-stage NSCLC and molecularly targeted therapy including thoughtful discussion on precise role of treatment strategies in specific tumors. Also, concerned diagnostics, new clinical trial designs, and pursuing appropriate combinations of radiotherapy and/or chemotherapy with biological therapy for exceptional cases considering resistance mechanisms and palliative care will be discussed.

Therapeutic Potential of Fingolimod and Dimethyl Fumarate in Non-Small Cell Lung Cancer Preclinical Models

New therapies are required for patients with non-small cell lung cancer (NSCLC) for which the current standards of care poorly affect the patient prognosis of this aggressive cancer subtype. In this preclinical study, we aim to investigate the efficacy of Fingolimod, a described inhibitor of sphingosine-1-phosphate (S1P)/S1P receptors axis, and Dimethyl Fumarate (DMF), a methyl ester of fumaric acid, both already approved as immunomodulators in auto-immune diseases with additional expected anti-cancer effects. The impact of both drugs was analyzed with in vitro cell survival analysis and in vivo graft models using mouse and human NSCLC cells implanted in immunocompetent or immunodeficient mice, respectively. We demonstrated that Fingolimod and DMF repressed tumor progression without apparent adverse effects in vivo in three preclinical mouse NSCLC models. In vitro, Fingolimod did not affect either the tumor proliferation or the cytotoxicity, although DMF reduced tumor cell proliferation. These results suggest that Fingolimod and DMF affected tumor progression through different cellular mechanisms within the tumor microenvironment. Fingolimod and DMF might uncover potential therapeutic opportunities in NSCLC.

Normal and Pathological NRF2 Signalling in the Central Nervous System

The nuclear factor erythroid 2-related factor 2 (NRF2) was originally described as a master regulator of antioxidant cellular response, but in the time since, numerous important biological functions linked to cell survival, cellular detoxification, metabolism, autophagy, proteostasis, inflammation, immunity, and differentiation have been attributed to this pleiotropic transcription factor that regulates hundreds of genes. After 40 years of in-depth research and key discoveries, NRF2 is now at the center of a vast regulatory network, revealing NRF2 signalling as increasingly complex. It is widely recognized that reactive oxygen species (ROS) play a key role in human physiological and pathological processes such as ageing, obesity, diabetes, cancer, and neurodegenerative diseases. The high oxygen consumption associated with high levels of free iron and oxidizable unsaturated lipids make the brain particularly vulnerable to oxidative stress. A good stability of NRF2 activity is thus crucial to maintain the redox balance and therefore brain homeostasis. In this review, we have gathered recent data about the contribution of the NRF2 pathway in the healthy brain as well as during metabolic diseases, cancer, ageing, and ageing-related neurodegenerative diseases. We also discuss promising therapeutic strategies and the need for better understanding of cell-type-specific functions of NRF2 in these different fields.

The sodium/myo-inositol co-transporter SLC5A3 promotes non-small cell lung cancer cell growth

Identification of novel molecular signaling targets for non-small cell lung cancer (NSCLC) is important. The present study examined expression, functions and possible underlying mechanisms of the sodium/myo-inositol co-transporter SLC5A3 in NSCLC. The Cancer Genome Atlas (TCGA) database and local NSCLC tissue results demonstrated that SLC5A3 expression in NSCLC tissues (including patient-derived primary NSCLC cells) was significantly higher than that in normal lung tissues and lung epithelial cells. In primary NSCLC cells and immortalized lines, SLC5A3 depletion, using small hairpin RNA (shRNA) and CRSIRP/Cas9 methods, robustly impeded cell proliferation and migration, simultaneously provoking cell cycle arrest and apoptosis. Conversely, ectopic overexpression of SLC5A3 further enhanced proliferation and migration in primary NSCLC cells. The intracellular myo-inositol contents and Akt-mTOR activation were largely inhibited by SLC5A3 silencing or knockout (KO), but were augmented following SLC5A3 overexpression in primary NSCLC cells. Significantly, SLC5A3 KO-induced anti-NSCLC cell activity was largely ameliorated by exogenously adding myo-inositol or by a constitutively-active Akt construct. By employing the patient-derived xenograft (PDX) model, we found that the growth of subcutaneous NSCLC xenografts in nude mice was largely inhibited by intratumoral injection SLC5A3 shRNA adeno-associated virus (AAV). SLC5A3 silencing, myo-inositol depletion, Akt-mTOR inactivation and apoptosis induction were detected in SLC5A3 shRNA virus-injected NSCLC xenograft tissues. Together, elevated SLC5A3 promotes NSCLC cell growth possibly by maintaining myo-inositol contents and promoting Akt-mTOR activation.

Oncogenic Pathways in Neurodegenerative Diseases

Cancer and neurodegenerative diseases are two of the leading causes of premature death in modern societies. Their incidence continues to increase, and in the near future, it is believed that cancer will kill more than 20 million people per year, and neurodegenerative diseases, due to the aging of the world population, will double their prevalence. The onset and the progression of both diseases are defined by dysregulation of the same molecular signaling pathways. However, whereas in cancer, these alterations lead to cell survival and proliferation, neurodegenerative diseases trigger cell death and apoptosis. The study of the mechanisms underlying these opposite final responses to the same molecular trigger is key to providing a better understanding of the diseases and finding more accurate treatments. Here, we review the ten most common signaling pathways altered in cancer and analyze them in the context of different neurodegenerative diseases such as Alzheimer's (AD), Parkinson's (PD), and Huntington's (HD) diseases.

Imaging the Rewired Metabolism in Lung Cancer in Relation to Immune Therapy

Metabolic reprogramming is recognized as one of the hallmarks of cancer. Alterations in the micro-environmental metabolic characteristics are recognized as important tools for cancer cells to interact with the resident and infiltrating T-cells within this tumor microenvironment. Cancer-induced metabolic changes in the micro-environment also affect treatment outcomes. In particular, immune therapy efficacy might be blunted because of somatic mutation-driven metabolic determinants of lung cancer such as acidity and oxygenation status. Based on these observations, new onco-immunological treatment strategies increasingly include drugs that interfere with metabolic pathways that consequently affect the composition of the lung cancer tumor microenvironment (TME). Positron emission tomography (PET) imaging has developed a wide array of tracers targeting metabolic pathways, originally intended to improve cancer detection and staging. Paralleling the developments in understanding metabolic reprogramming in cancer cells, as well as its effects on stromal, immune, and endothelial cells, a wave of studies with additional imaging tracers has been published. These tracers are yet underexploited in the perspective of immune therapy. In this review, we provide an overview of currently available PET tracers for clinical studies and discuss their potential roles in the development of effective immune therapeutic strategies, with a focus on lung cancer. We report on ongoing efforts that include PET/CT to understand the outcomes of interactions between cancer cells and T-cells in the lung cancer microenvironment, and we identify areas of research which are yet unchartered. Thereby, we aim to provide a starting point for molecular imaging driven studies to understand and exploit metabolic features of lung cancer to optimize immune therapy.

The role of glycometabolic plasticity in cancer

Dysregulated glycometabolism represented by the Warburg effect is well recognized as a hallmark of cancer that can be driven by oncogenes (e.g., c-Myc, K-ras, and BRAF) and contribute to cellular malignant transformation. The Warburg effect reveals the different glycometabolic patterns of cancer cells, but this unique glycometabolic pattern has the characteristic of plasticity rather than changeless which can vary with different internal or external stimuli during evolution. Glycometabolic plasticity enables cancer cells to modulate glycometabolism to support progression, metastasis, treatment resistance and recurrence. In this review, we report the characteristics of glycometabolic plasticity during different stages of cancer evolution, providing insight into the molecular mechanisms of glycometabolic plasticity in cancer. In addition, we discussed the challenges and future research directions of glycometabolism research in cancer.

Apatinib triggers autophagic and apoptotic cell death via VEGFR2/STAT3/PD-L1 and ROS/Nrf2/p62 signaling in lung cancer

Background

Recently, a variety of clinical trials have shown that apatinib, a small-molecule anti-angiogenic drug, exerts promising inhibitory effects on multiple solid tumors, including non-small cell lung cancer (NSCLC). However, the underlying molecular mechanism of apatinib on NSCLC remains unclear.

Methods

MTT, EdU, AO/EB staining, TUNEL staining, flow cytometry, colony formation assays were performed to investigate the effects of apatinib on cell proliferation, cell cycle distribution, apoptosis and cancer stem like properties. Wound healing and transwell assays were conducted to explore the role of apatinib on migration and invasion. The regulation of apatinib on VEGFR2/STAT3/PD-L1 and ROS/Nrf2/p62 signaling were detected. Furthermore, we collected conditioned medium (CM) from A549 and H1299 cells to stimulate phorbol myristate acetate (PMA)-activated THP-1 cells, and examined the effect of apatinib on PD-L1 expression in macrophages. The Jurkat T cells and NSCLC cells co-culture model was used to assess the effect of apatinib on T cells activation. Subcutaneous tumor formation models were established to evaluate the effects of apatinib in vivo. Histochemical, immunohistochemical staining and ELISA assay were used to examine the levels of signaling molecules in tumors.

Results

We showed that apatinib inhibited cell proliferation and promoted apoptosis in NSCLC cells in vitro. Apatinib induced cell cycle arrest at G1 phase and suppressed the expression of Cyclin D1 and CDK4. Moreover, apatinib upregulated Cleaved Caspase 3, Cleaved Caspase 9 and Bax, and downregulated Bcl-2 in NSCLC cells. The colony formation ability and the number of CD133 positive cells were significantly decreased by apatinib, suggesting that apatinib inhibited the malignant and stem-like features of NSCLC cells. Mechanistically, apatinib inhibited PD-L1 and c-Myc expression by targeting VEGFR2/STAT3 signaling. Apatinib also inhibited PD-L1 expression in THP-1 derived macrophages stimulated by CM from NSCLC cells. Furthermore, apatinib pretreatment increased CD69 expression and IFN-γ secretion in stimulated Jurkat T cells co-cultured with NSCLC cells. Apatinib also promoted ROS production and inhibited Nrf2 and p62 expression, leading to the autophagic and apoptotic cell death in NSCLC. Moreover, apatinib significantly inhibited tumor growth in vivo.

Conclusion

Our data indicated that apatinib induced autophagy and apoptosis in NSCLC via regulating VEGFR2/STAT3/PD-L1 and ROS/Nrf2/p62 signaling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02069-4.

Apatinib suppressed proliferation, induced cell cycle arrest and apoptosis, and inhibited malignancy in NSCLC in vitro and in vivo.

Apatinib downregulated PD-L1 and c-Myc in NSCLC through VEGFR2/STAT3 pathway.

Apatinib inhibited PD-L1 expression in THP-1 derived macrophages stimulated by the conditioned medium from NSCLC cells and partially restored the activation of Jurkat T cells co-cultured with NSCLC cells.

Apatinib induced ROS generation and inhibited Nrf2 and p62 expression, leading to the autophagic and apoptotic cell death in NSCLC.

Role of NRF2 in Lung Cancer

The gene expression program induced by NRF2 transcription factor plays a critical role in cell defense responses against a broad variety of cellular stresses, most importantly oxidative stress. NRF2 stability is fine-tuned regulated by KEAP1, which drives its degradation in the absence of oxidative stress. In the context of cancer, NRF2 cytoprotective functions were initially linked to anti-oncogenic properties. However, in the last few decades, growing evidence indicates that NRF2 acts as a tumor driver, inducing metastasis and resistance to chemotherapy. Constitutive activation of NRF2 has been found to be frequent in several tumors, including some lung cancer sub-types and it has been associated to the maintenance of a malignant cell phenotype. This apparently contradictory effect of the NRF2/KEAP1 signaling pathway in cancer (cell protection against cancer versus pro-tumoral properties) has generated a great controversy about its functions in this disease. In this review, we will describe the molecular mechanism regulating this signaling pathway in physiological conditions and summarize the most important findings related to the role of NRF2/KEAP1 in lung cancer. The focus will be placed on NRF2 activation mechanisms, the implication of those in lung cancer progression and current therapeutic strategies directed at blocking NRF2 action.

Discovery and characterization of novel peptide inhibitors of the NRF2/MAFG/DNA ternary complex for the treatment of cancer

Pathway activating mutations of the transcription factor NRF2 and its negative regulator KEAP1 are strongly correlative with poor clinical outcome with pemetrexed/carbo(cis)platin/pembrolizumab (PCP) chemo-immunotherapy in lung cancer. Despite the strong genetic support and therapeutic potential for a NRF2 transcriptional inhibitor, currently there are no known direct inhibitors of the NRF2 protein or its complexes with MAF and/or DNA. Herein we describe the design of a novel and high-confidence homology model to guide a medicinal chemistry effort that resulted in the discovery of a series of peptides that demonstrate high affinity, selective binding to the Antioxidant Response Element (ARE) DNA and thereby displace NRF2-MAFG from its promoter, which is an inhibitory mechanism that to our knowledge has not been previously described. In addition to their activity in electrophoretic mobility shift (EMSA) and TR-FRET-based assays, we show significant dose-dependent ternary complex disruption of NRF2-MAFG binding to DNA by SPR, as well as cellular target engagement by thermal destabilization of HiBiT-tagged NRF2 in the NCI-H1944 NSCLC cell line upon digitonin permeabilization, and SAR studies leading to improved cellular stability. We report the characterization and unique profile of lead peptide 18, which we believe to be a useful in vitro tool to probe NRF2 biology in cancer cell lines and models, while also serving as an excellent starting point for additional in vivo optimization toward inhibition of NRF2-driven transcription to address a significant unmet medical need in non-small cell lung cancer (NSCLC).

Diagnostic and Prognostic Significance of Keap1 mRNA Expression for Lung Cancer Based on Microarray and Clinical Information from Oncomine Database

We performed a bioinformatics analysis with validation by multiple databases, aiming to evaluate the diagnostic and prognostic value of Kelch-like ECH-associated protein 1 (Keap1) mRNA for lung cancer, and to explore possible mechanisms. Diagnostic performance of Keap1 mRNA was determined by receiver operating characteristic (ROC) curve analysis. Prognostic implication of Keap1 mRNA was estimated by Kaplan-Meier survival analysis. Co-expressed genes with both Keap1 and Nfe2L2 were identified by LinkedOmics. Mechanisms of Keap1-Nfe2L2-co-expressed genes underlying the pathogenesis of lung cancer were explored by function enrichment and pathway analysis. The ROC curve analysis determined a good diagnostic performance of Keap1 mRNA for lung squamous cell carcinoma (LUSC), with an area under the ROC curve (AUC) of 0.833, sensitivity of 72.7%, and specificity of 90.6% (P<0.001). Multivariate Cox regression recognized high Keap1 mRNA to be an independent risk factor of mortality for overall lung cancer [hazard ratio (HR): 11.034, P=0.044], but an independent antagonistic factor for lung adenocarcinoma (LUAD) (HR: 0.404, P<0.001). Validation by UALCAN and GEPIA supported Oncomine findings regarding the diagnostic value of Keap1 mRNA for LUSC, but denied its prognostic value. After screening, we identified 17 co-expressed genes with both Keap1 and Nfe2L2 for LUAD, and 22 for LUSC, mainly enriched in signaling pathway of oxidative stress-induced gene expression via Nrf2. In conclusion, Keap1 mRNA has a good diagnostic performance, but controversial prognostic efficacy for LUSC. The pathogenesis of lung cancer is associated with Keap1-Nfe2L2-co-expressed genes by signaling pathway of oxidative stress-induced gene expression via Nrf2.