Nfe2l1-silenced insulinoma cells acquire aggressiveness and chemoresistance

Metformin suppresses NFE2L1 pathway activation to inhibit gap junction beta protein expression in NSCLC

OBJECTIVE

Non-small-cell lung cancer (NSCLC) is a deadly form of cancer that exhibits extensive intercellular communication which contributed to chemoradiotherapy resistance. Recent evidence suggests that arrange of key proteins are involved in lung cancer progression, including gap junction proteins (GJPs).

METHODS AND RESULTS

In this study, we examined the expression patterns of GJPs in NSCLC, uncovering that both gap junction protein, beta 2 (GJB2) and gap junction protein, beta 2 (GJB3) are increased in LUAD and LUSC. We observed a correlation between the upregulation of GJB2, GJB3 in clinical samples and a worse prognosis in patients with NSCLC. By examining the mechanics, we additionally discovered that nuclear factor erythroid-2-related factor 1 (NFE2L1) had the capability to enhance the expression of connexin26 and connexin 31 in the NSCLC cell line A549. In addition, the use of metformin was discovered to cause significant downregulation of gap junction protein, betas (GJBs) by limiting the presence of NFE2L1 in the cytoplasm.

CONCLUSION

This emphasizes the potential of targeting GJBs as a viable treatment approach for NSCLC patients receiving metformin.

A new labdane diterpenoid from Scoparia dulcis improving pancreatic function against islets cell apoptotic by Bax/Bcl-2/Caspase-3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Scoparia dulcis has been identified as a significant ethnopharmacological substance in the Li, Zhuang, and Dai ethnic groups of China. Traditional medicine use S. dulcis to treat numerous illnesses, most notably diabetes. The considerable antidiabetic properties of this herbal remedy have been established by several clinical investigations and animal experiments. The islet is the intended target of S. dulcis, although the cause of its activity and mechanism for diabetes treatment is unclear. The diterpenoids from S. dulcis have been shown in the literature to have significant hypoglycemic efficacy and to protect islet cells in vitro. Diterpenoids may be the components of this herbal remedy that preserve islets, but further research is needed.

AIM OF THE STUDY

This study was projected to investigate the new diterpenoid scoparicol E from S. dulcis and examined its islet-protective effect and the potential mechanism both in vitro and in vivo.

METHODS

The structure of the novel diterpenoid scoparicol E was clarified by employing a wide range of spectroscopic methods. Using CCK-8 tests, cytotoxicity and antiapoptotic activity of scoparicol E were detected. Serum biochemical analysis and pathologic examination were performed to study the protective effect of scoparicol E against islet damage. The specific mechanism of action of scoparicol E was investigated through the mitochondrial membrane potential, Annexin V-FITC flow cytometry, and western blotting.

RESULTS

Scoparicol E reduced MLD-STZ-induced hyperglycemia in mice and increased insulin and islet apoptosis. Scoparicol E effectively suppressed the Bax/Bcl-2/Caspase-3 pathway, according to the in vivo western blot investigation. Scoparicol E showed significant antiapoptotic action in vitro. We also showed that scoparicol E might prevent islet cells from dying by inhibiting the Bax/Bcl-2/Caspase-3 pathway. The Annexin V-FITC flow cytometry results revealed that MIN6 cell apoptosis was considerably decreased following scoparicol E intervention, showing anti-islet cell apoptosis action. Furthermore, the Caspase-3-mediated apoptosis pathway depends on cytochrome c and the potential of the mitochondrial membrane. Scoparicol E prevented the release of cytochrome c, restored the mitochondrial membrane potential, and prevented MIN6 cell apoptosis.

CONCLUSION

We demonstrated the new diterpenoid scoparicol E could protect islet cells apoptosis by modulating the Bax/Bcl-2/Caspase-3 pathway.

Unravelling the role of NFE2L1 in stress responses and related diseases

The nuclear factor erythroid 2 (NF-E2)-related factor 1 (NFE2L1, also known as Nrf1) is a highly conserved transcription factor that belongs to the CNC-bZIP subfamily. Its significance lies in its control over redox balance, proteasome activity, and organ integrity. Stress responses encompass a series of compensatory adaptations utilized by cells and organisms to cope with extracellular or intracellular stress initiated by stressful stimuli. Recently, extensive evidence has demonstrated that NFE2L1 plays a crucial role in cellular stress adaptation by 1) responding to oxidative stress through the induction of antioxidative responses, and 2) addressing proteotoxic stress or endoplasmic reticulum (ER) stress by regulating the ubiquitin-proteasome system (UPS), unfolded protein response (UPR), and ER-associated degradation (ERAD). It is worth noting that NFE2L1 serves as a core factor in proteotoxic stress adaptation, which has been extensively studied in cancer and neurodegeneration associated with enhanced proteasomal stress. In these contexts, utilization of NFE2L1 inhibitors to attenuate proteasome "bounce-back" response holds tremendous potential for enhancing the efficacy of proteasome inhibitors. Additionally, abnormal stress adaptations of NFE2L1 and disturbances in redox and protein homeostasis contribute to the pathophysiological complications of cardiovascular diseases, inflammatory diseases, and autoimmune diseases. Therefore, a comprehensive exploration of the molecular basis of NFE2L1 and NFE2L1-mediated diseases related to stress responses would not only facilitate the identification of novel diagnostic and prognostic indicators but also enable the identification of specific therapeutic targets for NFE2L1-related diseases.

Biomedical importance of the ubiquitin-proteasome system in diabetes and metabolic transdifferentiation of pancreatic duct epithelial cells into β-cells

The ubiquitin-proteasome system (UPS) is a major pathway for cellular protein degradation. The molecular function of the UPS is the removal of damaged proteins, and this function is applied in many biological processes, including inflammation, proliferation, and apoptosis. Accumulating evidence also suggests that the UPS also has a key role in pancreatic β-cell transdifferentiation in diabetes and can be targeted for treatment of diabetic diseases. In this review, we summarized the mechanistic roles of the UPS in the biochemical activities of pancreatic β-cells, including the role of the UPS in insulin synthesis and secretion, as well as β-cell degradation. Also, we discuss how the UPS mediates the transdifferentiation of pancreatic duct epithelial cells into β-cells as the experimental basis for the development of new strategies for the treatment of diabetes in regenerative medicine.

Association of mitochondrial homeostasis and dynamic balance with malignant biological behaviors of gastrointestinal cancer

Mitochondria determine the physiological status of most eukaryotes. Mitochondrial dynamics plays an important role in maintaining mitochondrial homeostasis, and the disorder in mitochondrial dynamics could affect cellular energy metabolism leading to tumorigenesis. In recent years, disrupted mitochondrial dynamics has been found to influence the biological behaviors of gastrointestinal cancer with the potential to be a novel target for its individualized therapy. This review systematically introduced the role of mitochondrial dynamics in maintaining mitochondrial homeostasis, and further elaborated the effects of disrupted mitochondrial dynamics on the cellular biological behaviors of gastrointestinal cancer as well as its association with cancer progression. We aim to provide clues for elucidating the etiology and pathogenesis of gastrointestinal cancer from the perspective of mitochondrial homeostasis and disorder.

Immune and non-immune cell subtypes identify novel targets for prognostic and therapeutic strategy: A study based on intratumoral heterogenicity analysis of multicenter scRNA-seq datasets in lung adenocarcinoma

Lung adenocarcinoma (LUAD) is the most common type of lung cancer and the leading cause of cancer incidence and mortality worldwide. Despite the improvement of traditional and immunological therapies, the clinical outcome of LUAD is still far from satisfactory. Patients given the same treatment regimen had different responses and clinical outcomes due to the heterogeneity of LUAD. How to identify the targets based on heterogeneity analysis is crucial for treatment strategies. Recently, the single-cell RNA-sequencing (scRNA-seq) technology has been used to investigate the tumor microenvironment (TME) based on cell-specific changes and shows prominently valuable for biomarker prediction. In this study, we systematically analyzed a meta-dataset from the multiple LUAD scRNA-seq datasets in LUAD, identified 15 main types of cells and 57 cell subgroups, and revealed a series of potential biomarkers in M2b, exhausted CD8⁺T, endothelial cells, fibroblast, and metabolic patterns in TME, which further validated with immunofluorescence in clinical cohorts of LUAD. In the prognosis analysis, M0 macrophage and T cell activation were shown correlated to a better prognosis (p<0.05). Briefly, our study provided insights into the heterogeneity of LUAD and assisted in novel therapeutic strategies for clinical outcome improvement.

Natural COA water inhibits mitochondrial ROS-mediated apoptosis through Plk3 downregulation under STZ diabetic stress in pancreatic β-cell lines

Diabetes from pancreatic β cell death and insulin resistance is a serious metabolic disease in the world. Although the overproduction of mitochondrial reactive oxygen species (ROS) plays an important role in the pathogenesis of diabetes, its specific molecular mechanism remains unclear. Here, we show that the natural Charisma of Aqua (COA) water plays a role in Streptozotocin (STZ) diabetic stress-induced cell death inhibition. STZ induces mitochondrial ROS by increasing Polo-like kinase 3 (Plk3), a major mitotic regulator, in both Beta TC-6 and Beta TC-tet mouse islet cells and leads to apoptosis. Overexpression of Plk3 regulates an increase in mitochondrial ROS as well as cell death, also these events were inhibited by Plk3 gene knockdown in STZ diabetic stimulated-Beta TC-6 cells. Interestingly, we found that natural COA water blocks mitochondrial ROS generation through the reduction of Plk3 and prevents apoptosis in STZ-treated beta cells. Furthermore, using the 3D organoid (ex vivo) system, we confirmed that the insulin secretion of the supernatant medium under STZ treated pancreatic β-cells is protected by the natural COA water. These findings demonstrate that the natural water COA has a beneficial role in maintaining β cell function through the inhibition of mitochondrial ROS-mediated cell death, and it might be introduced as a potential insulin stabilizer.

•

Pancreatic β cell is stabilized through natural COA water in STZ-induced diabetes.

•

Mitochondrial membrane potential (ΔΨm) is controlled by natural COA water.

•

Plk3 expression under STZ treatment is negatively regulated by natural COA water.

•

Insulin secretion is stabilized by natural COA water under STZ treatment in ex vivo (3D organoid) model.

Long-isoform NFE2L1 silencing inhibits acquisition of malignant phenotypes induced by arsenite in human bronchial epithelial cells

Chronic arsenic exposure is associated with the increased risk of several types of cancer, among which, lung cancer is the most deadly one. Nuclear factor erythroid 2 like 1 (NFE2L1), a transcription factor belonging to CNC-bZIP family, regulates multiple important cellular functions in response to acute arsenite exposure. However, the role of NFE2L1 in lung cancer induced by chronic arsenite exposure is unknown. In this study, we firstly showed that chronic arsenite exposure (36 weeks) led to epithelial-mesenchymal transition (EMT) and malignant transformation in human bronchial epithelial cells (BEAS-2B). During the process of malignant transformation, the expression of long isoforms of NFE2L1 (NFE2L1-L) was elevated. Thereafter, BEAS-2B cells with NFE2L1-L stable knockdown (NFE2L1-L-KD) was chronically exposed to arsenite. As expected, silencing of NFE2L1-L gene strikingly inhibited the arsenite-induced EMT and the subsequent malignant transformation. Additionally, NFE2L1-L silencing suppressed the transcription of EMT-inducer SNAIL1 and increased the expression of E-cadherin. Conversely, NFE2L1-L overexpression increased SNAIL1 transcription but decreased E-cadherin expression. Collectively, our data suggest that NFE2L1-L promotes EMT by positively regulating SNAIL1 transcription, and is involved in malignant transformation induced by arsenite.

Prognostic Value and Immune Infiltration Analysis of Nuclear Factor Erythroid-2 Family Members in Ovarian Cancer

Ovarian cancer (OC) often presents at an advanced stage and is still one of the most frequent causes of gynecological cancer-related mortality worldwide. The nuclear factor erythroid-2 (NFE2) transcription factors include nuclear factor, erythroid 2 like 1 (NFE2L1), NFE2L2, and NFE2L3. NFE2 members bind to the antioxidant-response element (ARE) region and activate the expression of targeted genes. The distinct functions of NFE2 members in OC remain poorly elucidated. Several online bioinformatics databases were applied to determine gene expression, prognosis, mutations, and immune infiltration correlation in OC patients. NFE2L1 and NFE2L2 were decreased in OC, whereas NFE2L3 was increased. NFE2L2 and NFE2L3 were significantly correlated with the clinical stages of OC. High NFE2L1 level was significantly associated with short progression-free survival (PFS) in patients with OC ( $\text{HR}=1.18$ , $P=0.021$ ), while high NFE2L2 expression strongly correlated with long PFS ( $\text{HR}=0.77$ , $P=0.00067$ ). High NFE2L3 expression was associated with better overall survival and postprogression survival in OC. Functional analysis showed that NFE2 members mainly focused on transcription coactivator activities. Genetic alterations of NFE2 members were found in 13% of OC patients, and amplification ranked the top. The expression of NFE2 members was significantly correlated with immune infiltration of CD4+ T cells, CD8+ T cells, B cells, macrophages, and neutrophils in OC. Our study provides novel insights into the roles and prognostic potential of NFE2 family members in OC.

Nfe2l1 deficiency mitigates streptozotocin-induced pancreatic β-cell destruction and development of diabetes in male mice

Streptozotocin (STZ) is a pancreatic β cell-specific toxicant that is widely used to generate models of diabetes in rodents as well as in the treatment of tumors derived from pancreatic β cells. DNA alkylation, oxidative stress and mitochondrial toxicity have been recognized as the mechanisms for STZ-induced pancreatic β cell damage. Here, we found that pancreatic β cell-specific deficiency of nuclear factor erythroid-derived factor 2-related factor 1 (NFE2L1), a master regulator of the cellular adaptive response to a variety of stresses, in mice led to a dramatic resistance to STZ-induced hyperglycemia. Indeed, fifteen days subsequent to last dosage of STZ, the pancreatic β cell specific Nfe2l1 knockout [Nfe2l1(β)-KO] mice showed reduced hyperglycemia, improved glucose tolerance, higher plasma insulin and more intact islets surrounded by exocrine acini compared to the Nfe2l1-Flox control mice with the same treatment. Immunohistochemistry staining revealed a greater amount of insulin-positive cells in the pancreas of Nfe2l1(β)-KO mice than those in Nfe2l1-Flox mice 15 days after the last STZ injection. In line with this observation, both isolated Nfe2l1(β)-KO islets and Nfe2l1-deficient MIN6 (Nfe2l1-KD) cells were resistant to STZ-induced toxicity and apoptosis. Furthermore, pretreatment of the MIN6 cells with glycolysis inhibitor 2-Deoxyglucose sensitized Nfe2l1-KD cells to STZ-induced toxicity. These findings demonstrated that loss of Nfe2l1 attenuates pancreatic β cells damage and dysfunction caused by STZ exposure, partially due to Nfe2l1 deficiency-induced metabolic switch to enhanced glycolysis.

The roles of NFE2L1 in adipocytes: Structural and mechanistic insight from cell and mouse models

Adipocytes play pivotal roles in maintaining energy homeostasis by storing lipids in adipose tissue (AT), regulating the flux of lipids between AT and the circulation in response to the body's energy requirements and secreting a variety of hormones, cytokines and other factors. Proper AT development and function ensure overall metabolic health. Nuclear factor erythroid 2-related factor 1 (NFE2L1, also known as NRF1) belongs to the CNC-bZIP family and plays critical roles in regulating a wide range of essential cellular functions and varies stress responses in many cells and tissues. Human and rodent Nfe2l1 genes can be transcribed into multiple splice variants resulting in various protein isoforms, which may be further modified by a variety of post-translational mechanisms. While the long isoforms of NFE2L1 have been established as master regulators of cellular adaptive antioxidant response and proteasome homeostasis, the exact tissue distribution and physiological function of NFE2L1 isoforms, the short isoforms in particular, are still under intense investigation. With regard to key roles of NFE2L1 in adipocytes, emerging data indicates that deficiency of Nfe2l1 results in aberrant adipogenesis and impaired AT functioning. Intriguingly, a single nucleotide polymorphism (SNP) of the human NFE2L1 gene is associated with obesity. In this review, we summarize the most significant findings regarding the specific roles of the multiple isoforms of NFE2L1 in AT formation and function. We highlight that NFE2L1 plays a fundamental regulatory role in the expression of multiple genes that are crucial to AT metabolism and function and thus could be an important target to improve disease states involving aberrant adipose plasticity and lipid homeostasis.

Long-isoform NRF1 protects against arsenic cytotoxicity in mouse bone marrow-derived mesenchymal stem cells by suppressing mitochondrial ROS and facilitating arsenic efflux

Acute exposure to arsenic is known to cause bone marrow depression and result in anemia, in which the dusfunction of cells in the bone marrow niche such as mesenchymal stem cells (MSCs) is vital. However, the mechanism underlying response of MSCs to arsenic challange is not fully understood. In the present study, we investigated the role of nuclear factor erythroid 2-related factor (NRF) 1 (NRF1), a sister member of the well-known master regulator in antioxidative response NRF2, in arsenite-induced cytotoxicity in mouse bone marrow-derived MSCs (mBM-MSCs). We found that arsenite exposure induced significant increase in the protein level of long-isoform NRF1 (L-NRF1). Though short-isoform NRF1 (S-NRF1) was induced by arsenite at mRNA level, its protein level was not obviously altered. Silencing L-Nrf1 sensitized the cells to arsenite-induced cytotoxicity. L-Nrf1-silenced mBM-MSCs showed decreased arsenic efflux with reduced expression of arsenic transporter ATP-binding cassette subfamily C member 4 (ABCC4), as well as compromised NRF2-mediated antioxidative defense with elevated level of mitochondrial reactive oxygen species (mtROS) under arsenite-exposed conditions. A specific mtROS scavenger (Mito-quinone) alleviated cell apoptosis induced by arsenite in L-Nrf1-silenced mBM-MSCs. Taken together, these findings suggest that L-NRF1 protects mBM-MSCs from arsenite-induced cytotoxicity via suppressing mtROS in addition to facilitating cellular arsenic efflux.

ER-Resident Transcription Factor Nrf1 Regulates Proteasome Expression and Beyond

Protein folding is a substantively error prone process, especially when it occurs in the endoplasmic reticulum (ER). The highly exquisite machinery in the ER controls secretory protein folding, recognizes aberrant folding states, and retrotranslocates permanently misfolded proteins from the ER back to the cytosol; these misfolded proteins are then degraded by the ubiquitin–proteasome system termed as the ER-associated degradation (ERAD). The 26S proteasome is a multisubunit protease complex that recognizes and degrades ubiquitinated proteins in an ATP-dependent manner. The complex structure of the 26S proteasome requires exquisite regulation at the transcription, translation, and molecular assembly levels. Nuclear factor erythroid-derived 2-related factor 1 (Nrf1; NFE2L1), an ER-resident transcription factor, has recently been shown to be responsible for the coordinated expression of all the proteasome subunit genes upon proteasome impairment in mammalian cells. In this review, we summarize the current knowledge regarding the transcriptional regulation of the proteasome, as well as recent findings concerning the regulation of Nrf1 transcription activity in ER homeostasis and metabolic processes.