NRF2 preserves genomic integrity by facilitating ATR activation and G2 cell cycle arrest

14-3-3σ downregulation sensitizes pancreatic cancer to carbon ions by suppressing the homologous recombination repair pathway

This study explored the role of 14-3-3σ in carbon ion-irradiated pancreatic adenocarcinoma (PAAD) cells and xenografts and clarified the underlying mechanism. The clinical significance of 14-3-3σ in patients with PAAD was explored using publicly available databases. 14-3-3σ was silenced or overexpressed and combined with carbon ions to measure cell proliferation, cell cycle, and DNA damage repair. Immunoblotting and immunofluorescence (IF) assays were used to determine the underlying mechanisms of 14-3-3σ toward carbon ion radioresistance. We used the BALB/c mice to evaluate the biological behavior of 14-3-3σ in combination with carbon ions. Bioinformatic analysis revealed that PAAD expressed higher 14-3-3σ than normal pancreatic tissues; its overexpression was related to invasive clinicopathological features and a worse prognosis. Knockdown or overexpression of 14-3-3σ demonstrated that 14-3-3σ promoted the survival of PAAD cells after carbon ion irradiation. And 14-3-3σ was upregulated in PAAD cells during DNA damage (carbon ion irradiation, DNA damaging agent) and promotes cell recovery. We found that 14-3-3σ resulted in carbon ion radioresistance by promoting RPA2 and RAD51 accumulation in the nucleus in PAAD cells, thereby increasing homologous recombination repair (HRR) efficiency. Blocking the HR pathway consistently reduced 14-3-3σ overexpression-induced carbon ion radioresistance in PAAD cells. The enhanced radiosensitivity of 14-3-3σ depletion on carbon ion irradiation was also demonstrated in vivo. Altogether, 14-3-3σ functions in tumor progression and can be a potential target for developing biomarkers and treatment strategies for PAAD along with incorporating carbon ion irradiation.

Prevalence and Associations of Co-occurrence of NFE2L2 Mutations and Chromosome 3q26 Amplification in Lung Cancer

Background   NFE2L2 (nuclear factor erythroid-2-related factor-2) encodes a basic leucine zipper (bZIP) transcription factor and exhibits variations in various tumor types, including lung cancer. In this study, we comprehensively investigated the impact of simultaneous mutations on the survival of NFE2L2 -mutant lung cancer patients within specific subgroups. Methods  A cohort of 1,103 lung cancer patients was analyzed using hybridization capture-based next-generation sequencing. Results  The NFE2L2 gene had alterations in 3.0% (33/1,103) of lung cancer samples, including 1.5% (15/992) in adenocarcinoma and 16.2% (18/111) in squamous cell carcinoma. Thirty-four variations were found, mainly in exons 2 (27/34). New variations in exon 2 (p.D21H, p.V36_E45del, p.F37_E45del, p.R42P, p.E67Q, and p.L76_E78delinsQ) were identified. Some patients had copy number amplifications. Co-occurrence with TP53 (84.8%), CDKN2A (33.3%), KMT2B (33.3%), LRP1B (33.3%), and PIK3CA (27.3%) mutations was common. Variations of NFE2L2 displayed the tightest co-occurrence with IRF2 , TERC , ATR , ZMAT3 , and SOX2 ( p  < 0.001). In The Cancer Genome Atlas Pulmonary Squamous Carcinoma project, patients with NFE2L2 variations and 3q26 amplification had longer median survival (63.59 vs. 32.04 months, p  = 0.0459) and better overall survival. Conclusions   NFE2L2 mutations display notable heterogeneity in lung cancer. The coexistence of NFE2L2 mutations and 3q26 amplification warrants in-depth exploration of their potential clinical implications and treatment approaches for affected patients.

Radiation and male reproductive system: Damage and protection

Male fertility has been declining in recent decades, and a growing body of research points to environmental and lifestyle factors as the cause. The widespread use of radiation technology may result in more people affected by male infertility, as it is well established that radiation can cause reproductive impairment in men. This article provides a review of radiation-induced damage to male reproduction, and the effects of damage mechanisms and pharmacotherapy. It is hoped that this review will contribute to the understanding of the effects of radiation on male reproduction, and provide information for research into drugs that can protect the reproductive health of males.

ReCorDE: a framework for identifying drug classes targeting shared vulnerabilities with applications to synergistic drug discovery

Cancer is typically treated with combinatorial therapy, and such combinations may be synergistic. However, discovery of these combinations has proven difficult as brute force combinatorial screening approaches are both logistically complex and resource-intensive. Therefore, computational approaches to augment synergistic drug discovery are of interest, but current approaches are limited by their dependencies on combinatorial drug screening training data or molecular profiling data. These dataset dependencies can limit the number and diversity of drugs for which these approaches can make inferences. Herein, we describe a novel computational framework, ReCorDE (Recurrent Correlation of Drugs with Enrichment), that uses publicly-available cell line-derived monotherapy cytotoxicity datasets to identify drug classes targeting shared vulnerabilities across multiple cancer lineages; and we show how these inferences can be used to augment synergistic drug combination discovery. Additionally, we demonstrate in preclinical models that a drug class combination predicted by ReCorDE to target shared vulnerabilities (PARP inhibitors and Aurora kinase inhibitors) exhibits class-class synergy across lineages. ReCorDE functions independently of combinatorial drug screening and molecular profiling data, using only extensive monotherapy cytotoxicity datasets as its input. This allows ReCorDE to make robust inferences for a large, diverse array of drugs. In conclusion, we have described a novel framework for the identification of drug classes targeting shared vulnerabilities using monotherapy cytotoxicity datasets, and we showed how these inferences can be used to aid discovery of novel synergistic drug combinations.

Autocorrelation analysis of a phenotypic screen reveals hidden drug activity

Phenotype based screening is a powerful tool to evaluate cellular drug response. Through high content fluorescence imaging of simple fluorescent labels and complex image analysis phenotypic measurements can identify subtle compound-induced cellular changes unique to compound mechanisms of action (MoA). Recently, a screen of 1008 compounds in three cell lines was reported where analysis detected changes in cellular phenotypes and accurately identified compound MoA for roughly half the compounds. However, we were surprised that DNA alkylating agents and other compounds known to induce or impact the DNA damage response produced no measured activity in cells with fluorescently labeled 53BP1-a canonical DNA damage marker. We hypothesized that phenotype analysis is not sensitive enough to detect small changes in 53BP1 distribution and analyzed the screen images with autocorrelation image analysis. We found that autocorrelation analysis, which quantifies fluorescently-labeled protein clustering, identified higher compound activity for compounds and MoAs known to impact the DNA damage response, suggesting altered 53BP1 recruitment to damaged DNA sites. We then performed experiments under more ideal imaging settings and found autocorrelation analysis to be a robust measure of changes to 53BP1 clustering in the DNA damage response. These results demonstrate the capacity of autocorrelation to detect otherwise undetectable compound activity and suggest that autocorrelation analysis of specific proteins could serve as a powerful screening tool.

A multi-mode Rhein-based nano-platform synergizing ferrotherapy/chemotherapy-induced immunotherapy for enhanced tumor therapy

Ferroptosis has emerged as a promising strategy for treating triple-negative breast cancer (TNBC) due to bypassing apoptosis and triggering immunogenic cell death (ICD) of tumor cells. However, the antitumor efficacy has been limited by the insufficient intracellular ferrous iron concentration required for ferroptosis and inadequate antitumor immune response. To address these limitations, we designed a multi-mode nano-platform (MP-FA@R-F NPs), which exhibited a synergistic effect of ferroptosis, apoptosis and induced immune response for enhanced antitumor therapy. MP-FA@R-F NPs target folate receptors, which are over-expressed on the tumor cell's surface to promote intracellular uptake. The cargoes, including Rhein and Fe3O4, would be released in intracellular acid, accelerating by NIR laser irradiation. The released Rhein induced apoptosis of tumor cells mediated by the caspase 3 signal pathway, while the released Fe3O4 triggered ferroptosis through the Fenton reaction and endowed the nanoplatform with magnetic resonance imaging (MRI) capabilities. In addition, ferroptosis-dying tumor cells could release damage-associated molecular patterns (DAMPs) to promote T cell activation and infiltration for immune response and induce immunogenic cell death (ICD) for tumor immunotherapy. Together, MP-FA@R-F NPs represent a potential synergistic ferro-/chemo-/immuno-therapy strategy with MRI guidance for enhanced antitumor therapy. STATEMENT OF SIGNIFICANCE: The massive strategies of cancer therapy based on ferroptosis have been emerging in recent years, which provided new insights into designing materials for cancer therapy. However, the antitumor efficacy of ferroptosis is still unsatisfactory, mainly due to insufficient intracellular pro-ferroptotic stimuli. In the current study, we designed a multi-mode nano-platform (MP-FA@R-F NPs), which represented a potential synergistic ferro-/chemo-/immuno-therapy strategy with MRI guidance for enhanced antitumor therapy.

Glutathione Depletion-Induced Versatile Nanomedicine for Potentiating the Ferroptosis to Overcome Solid Tumor Radioresistance and Enhance Immunotherapy

A high level of reduced glutathione is a major factor contributing to the radioresistance observed in solid tumors. To address this radioresistance associated with glutathione, a cinnamaldehyde (CA) polymer prodrug, referred to as PDPCA, is fabricated. This prodrug is created by synthesizing a pendent CA prodrug with acetal linkages in a hydrophobic block, forming a self-assembled into a core-shell nanoparticle in aqueous media. Additionally, it encapsulates all-trans retinoic acid (ATRA) for synchronous delivery, resulting in PDPCA@ATRA. The PDPCA@ATRA nanoparticles accumulate reactive oxygen species through both endogenous and exogenous pathways, enhancing ferroptosis by depleting glutathione. This approach demonstrates efficacy in overcoming tumor radioresistance in vivo and in vitro, promoting the ferroptosis, and enhancing the cytotoxic T lymphocyte (CTL) response for lung tumors to anti-PD-1 (αPD-1) immunotherapy. Furthermore, this study reveals that PDPCA@ATRA nanoparticles promote ferroptosis through the NRF2-GPX4 signaling pathway, suggesting the potential for further investigation into the combination of radiotherapy and αPD-1 immune checkpoint inhibitors in cancer treatment.

Toxoflavin analog D43 exerts antiproliferative effects on breast cancer by inducing ROS-mediated apoptosis and DNA damage

Triple-negative breast cancer (TNBC) is regarded as the deadliest subtype of breast cancer because of its high heterogeneity, aggressiveness, and limited treatment options. Toxoflavin has been reported to possess antitumor activity. In this study, a series of toxoflavin analogs were synthesized, among which D43 displayed a significant dose-dependent inhibitory effect on the proliferation of TNBC cells (MDA-MB-231 and HCC1806). Additionally, D43 inhibited DNA synthesis in TNBC cells, leading to cell cycle arrest at the G2/M phase. Furthermore, D43 consistently promoted intracellular ROS generation, induced DNA damage, and resulted in apoptosis in TNBC cells. These effects could be reversed by N-acetylcysteine. Moreover, D43 significantly inhibited the growth of breast cancer patient-derived organoids and xenografts with a favorable biosafety profile. In conclusion, D43 is a potent anticancer agent that elicits significant antiproliferation, oxidative stress, apoptosis, and DNA damage effects in TNBC cells, and D43 holds promise as a potential candidate for the treatment of TNBC.

Regulation of antioxidants in cancer

Scientists in this field often joke, "If you don't have a mechanism, say it's ROS." Seemingly connected to every biological process ever described, reactive oxygen species (ROS) have numerous pleiotropic roles in physiology and disease. In some contexts, ROS act as secondary messengers, controlling a variety of signaling cascades. In other scenarios, they initiate damage to macromolecules. Finally, in their worst form, ROS are deadly to cells and surrounding tissues. A set of molecules with detoxifying abilities, termed antioxidants, is the direct counterpart to ROS. Notably, antioxidants exist in the public domain, touted as a "cure-all" for diseases. Research has disproved many of these claims and, in some cases, shown the opposite. Of all the diseases, cancer stands out in its paradoxical relationship with antioxidants. Although the field has made numerous strides in understanding the roles of antioxidants in cancer, many questions remain.

NRF2 promotes radiation resistance by cooperating with TOPBP1 to activate the ATR-CHK1 signaling pathway

Background: Radiation resistance is the main limitation of the application of radiotherapy. Ionizing radiation (IR) kills cancer cells mainly by causing DNA damage, particularly double-strand breaks (DSBs). Radioresistant cancer cells have developed the robust capability of DNA damage repair to survive IR. Nuclear factor erythroid 2-related factor 2 (NRF2) has been correlated with radiation resistance. We previously reported a novel function of NRF2 as an ATR activator in response to DSBs. However, little is known about the mechanism that how NRF2 regulates DNA damage repair and radiation resistance. Methods: The TCGA database and tissue microarray were used to analyze the correlation between NRF2 and the prognosis of lung cancer patients. The radioresistant lung cancer cells were constructed, and the role of NRF2 in radiation resistance was explored by in vivo and in vitro experiments. Immunoprecipitation, immunofluorescence and extraction of chromatin fractions were used to explore the underlying mechanisms. Results: In this study, the TCGA database and clinical lung cancer samples showed that high expression of NRF2 was associated with poor prognosis in lung cancer patients. We established radioresistant lung cancer cells expressing NRF2 at high levels, which showed increased antioxidant and DNA repair abilities. In addition, we found that NRF2 can be involved in the DNA damage response independently of its antioxidant function. Mechanistically, we demonstrated that NRF2 promoted the phosphorylation of replication protein A 32 (RPA32), and DNA topoisomerase 2-binding protein 1 (TOPBP1) was recruited to DSB sites in an NRF2-dependent manner. Conclusion: This study explored the novel role of NRF2 in promoting radiation resistance by cooperating with RPA32 and TOPBP1 to activate the ATR-CHK1 signaling pathway. In addition, the findings of this study not only provide novel insights into the molecular mechanisms underlying the radiation resistance of lung cancer cells but also validate NRF2 as a potential target for radiotherapy.

Roles of NRF2 in DNA damage repair

PURPOSE

The transcription factor NF-E2-related factor 2 (NRF2) is a master regulator widely involved in essential cellular functions such as DNA repair. By clarifying the upstream and downstream links of NRF2 to DNA damage repair, we hope that attention will be drawn to the utilization of NRF2 as a target for cancer therapy.

METHODS

Query and summarize relevant literature on the role of NRF2 in direct repair, BER, NER, MMR, HR, and NHEJ in pubmed. Make pictures of Roles of NRF2 in DNA Damage Repair and tables of antioxidant response elements (AREs) of DNA repair genes. Analyze the mutation frequency of NFE2L2 in different types of cancer using cBioPortal online tools. By using TCGA, GTEx and GO databases, analyze the correlation between NFE2L2 mutations and DNA repair systems as well as the degree of changes in DNA repair systems as malignant tumors progress.

RESULTS

NRF2 plays roles in maintaining the integrity of the genome by repairing DNA damage, regulating the cell cycle, and acting as an antioxidant. And, it possibly plays roles in double stranded break (DSB) pathway selection following ionizing radiation (IR) damage. Whether pathways such as RNA modification, ncRNA, and protein post-translational modification affect the regulation of NRF2 on DNA repair is still to be determined. The overall mutation frequency of the NFE2L2 gene in esophageal carcinoma, lung cancer, and penile cancer is the highest. Genes (50 of 58) that are negatively correlated with clinical staging are positively correlated with NFE2L2 mutations or NFE2L2 expression levels.

CONCLUSION

NRF2 participates in a variety of DNA repair pathways and plays important roles in maintaining genome stability. NRF2 is a potential target for cancer treatment.

SUMO1 Modification Stabilizes TET3 Protein and Increases Colorectal Cancer Radiation Therapy Sensitivity

PURPOSE

The aim of this work was to explore the role and mechanism of active DNA demethylase in colorectal cancer (CRC) radiation sensitization and better understand the function of DNA demethylation in tumor radiosensitization.

METHODS AND MATERIALS

Tested the effect of ten-eleven translocation 3 (TET3) overexpression on the sensitivity of CRC to radiation therapy through G2/M arrest, apoptosis, and clonogenic suppression. TET3 knockdown HCT 116 and TET3 knockdown LS 180 cell lines were constructed by siRNA technology, and the effect of exogenous knockdown of TET3 on radiation-induced apoptosis, cell cycle arrest, DNA damage, and clone formation in CRC cells were detected. The co-localization of TET3 and small ubiquitin-like modifier 1 (SUMO1), SUMO2/3 was detected by immunofluorescence and cytoplasmic-nuclear extraction, and the interaction between TET3 and SUMO1, SUMO2/3 was detected by a coimmunoprecipitation assay.

RESULTS

The malignant phenotype and radiosensitivity of CRC cell lines were favorably linked with TET3 protein and mRNA expression. TET3 is upregulated in 23 of the 27 tumor types investigated, including colon cancer. TET3 was shown to correlate with the CRC pathologic malignancy grade positively. Overexpression of TET3 in CRC cell lines increased radiation-induced apoptosis, G2/M phase arrest, DNA damage, and clonal suppression in vitro. The binding region of TET3 and SUMO2/3 was located at 833-1795 AA except for K1012, K1188, K1397, and K1623. SUMOylation of TET3 increased the stability of the TET3 protein without changing its nuclear localization.

CONCLUSIONS

We report the sensitizing role of TET3 protein in the radiation of CRC cells, depending on SUMO1 modification of TET3 at the lysine sites (K479, K758, K1012, K1188, K1397, K1623), in turn stabilizing TET3 expression in the nucleus and subsequently increasing the sensitivity of CRC to radiation therapy. Together, this study highlights the potentially critical role of TET3 SUMOylation in radiation regulation, which may contribute to an enhanced understanding of the relationship between DNA demethylation and radiation therapy.

Multifunctional Au@AgBiS2 Nanoparticles as High-Efficiency Radiosensitizers to Induce Pyroptosis for Cancer Radioimmunotherapy

Radiotherapy (RT), a widely used clinical treatment modality for cancer, uses high-energy irradiation for reactive oxygen species (ROS) production and DNA damage. However, its therapeutic effect is primarily limited owing to insufficient DNA damage to tumors and harmful effects on normal tissues. Herein, a core-shell structure of metal-semiconductors (Au@AgBiS2 nanoparticles) that can function as pyroptosis inducers to both kill cancer cells directly and trigger a robust anti-tumor immune against 4T1 triple-negative murine breast cancer and metastasis is rationally designed. Metal-semiconductor composites can enhance the generation of considerable ROS and simultaneously DNA damage for RT sensitization. Moreover, Au@AgBiS2 , a pyroptosis inducer, induces caspase-3 protein activation, gasdermin E cleavage, and the release of damage-associated molecular patterns. In vivo studies in BALB/c mice reveal that Au@AgBiS2 nanoparticles combined with RT exhibit remarkable antitumor immune activity, preventing tumor growth, and lung metastasis. Therefore, this core-shell structure is an alternative for designing highly effective radiosensitizers for radioimmunotherapy.

New horizons in lung cancer management through ATR/CHK1 pathway modulation

Lung cancer is the leading cause of cancer-related deaths worldwide. Molecular profiling has contributed to a new classification of lung cancer, driving advancements in research and therapy. The ataxia telangiectasia and rad3/checkpoint kinase 1 (ATR/CHK1) pathway plays a crucial role in maintaining genomic stability, and its activation has been linked to the development of lung cancer, drug resistance and poor prognosis. Clinical and preclinical studies have demonstrated promising results in targeting this pathway. ATR and CHK1 are proteins that collaborate to repair DNA damage caused by radiation or chemotherapy. ATR/CHK1 inhibitors are currently under investigation in preclinical and clinical trials. This article explores the ATR/CHK1 pathway and its potential for treating lung cancer.

Cancer-Erythrocyte Membrane-Mimicking Fe3O4 Nanoparticles and DHJS for Ferroptosis/Immunotherapy Synergism in Tumors

Ferroptosis is characterized by iron accumulation and lipid peroxidation. However, a clinical dose of Fe3O4 nanoparticles could not cause effective ferroptosis in tumors, and the mechanism is yet to be completely understood. In this study, using RNA-seq data, we found that tumor cells could feedback-activate the antioxidant system by upregulating Nrf-2 expression, thus avoiding ferroptosis caused by Fe3O4 nanoparticles. We also found that DHJS (a probe for ROS generation) can antagonize Nrf-2 expression when it synergizes with Fe3O4 nanoparticles, thus inducing ferroptosis in tumor cells. Considering these findings, we created a biomimetic hybrid cell membrane camouflaged by PLGA-loaded Fe3O4 and DHJS to treat osteosarcoma. The hybrid cell membrane endowed the core nanoparticle with the extension of blood circulation life and enhanced homologous targeting ability. In addition, DHJS and Fe3O4 in nanoparticles prompted synergistically lethal ferroptosis in cancer cells and induced macrophage M1 polarization as well as the infiltration of CD8(+) T cells and dendritic cells in tumors. In summary, this study provides novel mechanistic insights and practical strategies for ferroptosis induction of Fe3O4 nanoparticles. Meanwhile, the synthesized biomimetic nanoparticles exhibited synergistic ferroptosis/immunotherapy against osteosarcoma.

A homologous and molecular dual-targeted biomimetic nanocarrier for EGFR-related non-small cell lung cancer therapy

The abnormal activation of epidermal growth factor receptor (EGFR) drives the development of non-small cell lung cancer (NSCLC). The EGFR-targeting tyrosine kinase inhibitor osimertinib is frequently used to clinically treat NSCLC and exhibits marked efficacy in patients with NSCLC who have an EGFR mutation. However, free osimertinib administration exhibits an inadequate response in vivo, with only ∼3% patients demonstrating a complete clinical response. Consequently, we designed a biomimetic nanoparticle (CMNP^@Osi) comprising a polymeric nanoparticle core and tumor cell-derived membrane-coated shell that combines membrane-mediated homologous and molecular targeting for targeted drug delivery, thereby supporting a dual-target strategy for enhancing osimertinib efficacy. After intravenous injection, CMNP^@Osi accumulates at tumor sites and displays enhanced uptake into cancer cells based on homologous targeting. Osimertinib is subsequently released into the cytoplasm, where it suppresses the phosphorylation of upstream EGFR and the downstream AKT signaling pathway and inhibits the proliferation of NSCLC cells. Thus, this dual-targeting strategy using a biomimetic nanocarrier can enhance molecular-targeted drug delivery and improve clinical efficacy.

Role of Nrf2 in 1,2-dichloropropane-induced cell proliferation and DNA damage in the mouse liver

1,2-Dichloropropane (1,2-DCP) is recognized as the causative chemical of occupational cholangiocarcinoma in printing workers in Japan. However, the cellular and molecular mechanisms of 1,2-DCP-induced carcinogenesis remains elusive. The present study investigated cellular proliferation, DNA damage, apoptosis, and expression of antioxidant and proinflammatory genes in the liver of mice exposed daily to 1,2-DCP for 5 weeks, and the role of nuclear factor erythroid 2-related factor 2 (Nrf2) in these responses. Wild-type and Nrf2-knockout (Nrf2-/-) mice were administered 1,2-DCP by gastric gavage, and then the livers were collected for analysis. Immunohistochemistry for BrdU or Ki67 and TUNEL assay revealed that exposure to 1,2-DCP dose-dependently increased proliferative cholangiocytes, whereas decreased apoptotic cholangiocytes in wild-type mice but not in Nrf2-/- mice. Western blot and quantitative real-time PCR showed that exposure to 1,2-DCP increased the levels of DNA double-strand break marker γ-H2AX and mRNA expression levels of NQO1, xCT, GSTM1, and G6PD in the livers of wild-type mice in a dose-dependent manner, but no such changes were noted in Nrf2-/- mice. 1,2-DCP increased glutathione levels in the liver of both the wild-type and Nrf2-/- mice, suggesting that an Nrf2-independent mechanism contributes to 1,2-DCP-induced increase in glutathione level. In conclusion, the study demonstrated that exposure to 1,2-DCP induced proliferation but reduced apoptosis in cholangiocytes, and induced double-strand DNA breaks and upregulation of antioxidant genes in the liver in an Nrf2-dependent manner. The study suggests a role of Nrf2 in 1,2-DCP-induced cell proliferation, antiapoptotic effect, and DNA damage, which are recognized as key characteristics of carcinogens.

Aging, NRF2, and TAU: A Perfect Match for Neurodegeneration?

Although the trigger for the neurodegenerative disease process is unknown, the relevance of aging stands out as a major risk for the development of neurodegeneration. In this review, we highlighted the relationship between the different cellular mechanisms that occur as a consequence of aging and transcription factor nuclear factor erythroid-2-related factor 2 (NRF2) and the connection with the TAU protein. We focused on the relevance of NRF2 in the main processes involved in neurodegeneration and associated with aging, such as genomic instability, protein degradation systems (proteasomes/autophagy), cellular senescence, and stem cell exhaustion, as well as inflammation. We also analyzed the effect of aging on TAU protein levels and its aggregation and spread process. Finally, we investigated the interconnection between NRF2 and TAU and the relevance of alterations in the NRF2 signaling pathway in both primary and secondary tauopathies. All these points highlight NRF2 as a possible therapeutic target for tauopathies.

Ionizing radiation triggers mitophagy to enhance DNA damage in cancer cells

Radiotherapy is an important cancer treatment strategy that causes DNA damage in tumor cells either directly or indirectly. Autophagy is a physiological process linked to DNA damage. Mitophagy is a form of autophagy, which specifically targets and eliminates impaired mitochondria, thereby upholding cellular homeostasis. However, the connection between DNA damage and mitophagy has yet to be fully elucidated. We found that mitophagy, as an upstream signal, increases ionizing radiation-induced DNA damage by downregulating or overexpressing key mitophagy proteins Parkin and BNIP3. Enhancing the basal level of mitophagy in conjunction with X-ray irradiation can potentially diminish cell cycle arrest at the G2/M phase, substantially elevate the accumulation of γ-H2AX, 53BP1, and PARP1 foci within the nucleus, augment DNA damage, and facilitate the demise of tumor cells. Consequently, this approach prolongs the survival of melanoma-bearing mice. The findings of this study are anticipated to offer a therapeutic approach for enhancing the therapeutic effectiveness of radiotherapy.

Roles of Oxidative Stress and Nrf2 Signaling in Pathogenic and Non-Pathogenic Cells: A Possible General Mechanism of Resistance to Therapy

The coordinating role of nuclear factor erythroid-2-related factor 2 (Nrf2) in cellular function is undeniable. Evidence indicates that this transcription factor exerts massive regulatory functions in multiple signaling pathways concerning redox homeostasis and xenobiotics, macromolecules, and iron metabolism. Being the master regulator of antioxidant system, Nrf2 controls cellular fate, influencing cell proliferation, differentiation, apoptosis, resistance to therapy, and senescence processes, as well as infection disease success. Because Nrf2 is the key coordinator of cell defence mechanisms, dysregulation of its signaling has been associated with carcinogenic phenomena and infectious and age-related diseases. Deregulation of this cytoprotective system may also interfere with immune response. Oxidative burst, one of the main microbicidal mechanisms, could be impaired during the initial phagocytosis of pathogens, which could lead to the successful establishment of infection and promote susceptibility to infectious diseases. There is still a knowledge gap to fill regarding the molecular mechanisms by which Nrf2 orchestrates such complex networks involving multiple pathways. This review describes the role of Nrf2 in non-pathogenic and pathogenic cells.

BDE-209 induced spermatogenesis disorder by inhibiting SETD8/H4K20me1 related histone methylation in mice

Past studies have observed that decabromodiphenyl ether (BDE-209) induces reproductive and developmental toxicity, but the specific mechanism remains unclear. Based on our previous work, male mice were orally given BDE-209 at 75 mg/kg/d via continuous exposure for one spermatozoon development period (50 days) and then stopping exposure for another 50 days. The mouse spermatocyte line GC-2spd was used to examine the toxic effects of BDE-209 on histone methylation and spermatogenesis. The findings indicated that BDE-209 damaged testis and epididymis structure, induced spermatogenic cell apoptosis, and decreased sperm quantity and quality after the 50-day exposure. Furthermore, BDE-209 lowered the levels of SETD8/H4K20me1 and activated the upstream signaling of DNA damage response (Mre11/Rad50/NBS1), thereby causing spermatogenic cell cycle arrest and apoptosis. Downregulation of meiotic promoter Stra8 was associated with a decrease in SETD8 after BDE-209 exposure. After stopping the exposure for 50 days, reproductive system damage and meiosis and cell cycle inhibition due to histone methylation did not improve. In vitro experiments revealed that Setd8 overexpression upregulated the histone methylation and Stra8 expression but did not promote the cell cycle in GC-2 cells. Therefore, BDE-209 exposure impaired spermatogenesis by affecting SETD8/H4K20me1-linked histone methylation and inhibiting meiosis initiation and cell cycle progression, thereby resulting in long-term male reproductive toxicity.

Diesel exhaust particle exposure accelerates oxidative DNA damage and cytotoxicity in normal human bronchial epithelial cells through PD-L1

Diesel exhaust particles (DEPs) are a major cause of cancer progression as well as a variety of acute and chronic diseases. It is well-known that programmed death-ligand 1 (PD-L1) is an immune checkpoint molecule that can induce immune escape in tumor cells. However, the function of PD-L1 in bronchial epithelial cells or how PD-L1 relates to cellular oxidation under DEPs-mediated oxidative stress is not well known. In this study, we investigated how PD-L1 affected DEPs-induced oxidative stress and cytotoxicity in human bronchial epithelial (HBE) cells, Beas-2B. DEPs not only induced intracellular reactive oxygen species (ROS) production, but also increased PD-L1 expression in HBE cells. Beas-2B cells overexpressing PD-L1 showed higher levels of ROS production, DNA damage, and apoptosis after DEPs treatment compared to control cells. In particular, the expression of an antioxidant enzyme heme-oxygenase-1 (HO-1) and nuclear translocation and transcriptional activity of Nrf2, a major regulator of HO-1, were lower in Beas-2B overexpressing PD-L1 cells than in control cells. DEPs-induced ROS generation, DNA damage and apoptosis in Beas-2B cells overexpressing PD-L1 were significantly restored by overexpressing HO-1. Collectively, our results suggest that DEPs can increase the expression of PD-L1 in HBE cells and that overexpressing PD-L1 might eventually promote DEPs-induced oxidative DNA damage and apoptosis.

Adaptive regulations of Nrf2 alleviates silver nanoparticles-induced oxidative stress-related liver cells injury

Silver nanoparticles (AgNPs) are widely used in various fields such as industry, agriculture, and medical care because of their excellent broad-spectrum antibacterial activity. However, their extensive use has raised concerns about their health risks. Liver is one of the main target organs for the accumulation and action of AgNPs. Therefore, evaluating the toxic effects of AgNPs on liver cells and its mechanisms of action is crucial for the safe application of AgNPs. In the study, polyvinylpyrrolidone (PVP)-coated AgNPs were characterized. The human hepatoma cell line (HepG2) and the normal hepatic cell line (L02) were exposed to different concentrations of AgNPs (20-160 μg/mL) and pretreated with the addition of N-acetylcysteine (NAC) or by Nrf2 siRNA transfection. NAC was able to inhibit the concentration-dependent increase in the level of apoptosis induced by AgNPs in HepG2 cells and L02 cells. Interestingly, HepG2 cells were more sensitive to AgNPs than L02 cells, and this may be related to the different ROS generation and responses to AgNPs by cancer cells and normal cells. In addition, NAC also alleviated the imbalance of antioxidant system and cell cycle arrest, which may be related to AgNPs-induced DNA damage and autophagy. The knockdown of nuclear factor erythroid-derived factor 2-related factor (Nrf2) found that AgNPs-induced ROS and apoptosis levels were further upregulated, but the cell cycle arrest was alleviated. On the whole, Nrf2 exerts a protective role in AgNPs-induced hepatotoxicity. This study complements the hepatotoxicity mechanisms of AgNPs and provides data for a future exploration of AgNPs-related anti-hepatocellular carcinoma drugs.

Nrf2-/- regulated lung DNA demethylation and CYP2E1 DNA methylation under PM2.5 exposure

Cytochrome P450 (CYP450) can mediate fine particulate matter (PM_2.5) exposure leading to lung injury. Nuclear factor E2-related factor 2 (Nrf2) can regulate CYP450 expression; however, the mechanism by which Nrf2^-/- (KO) regulates CYP450 expression via methylation of its promoter after PM_2.5 exposure remains unclear. Here, Nrf2^-/- (KO) mice and wild-type (WT) were placed in a PM_2.5 exposure chamber (PM) or a filtered air chamber (FA) for 12 weeks using the real-ambient exposure system. The CYP2E1 expression trends were opposite between the WT and KO mice following PM_2.5 exposure. After exposure to PM_2.5, CYP2E1 mRNA and protein levels were increased in WT mice but decreased in KO mice, and CYP1A1 expression was increased after exposure to PM_2.5 in both WT and KO mice. CYP2S1 expression decreased after exposure to PM_2.5 in both the WT and KO groups. We studied the effect of PM_2.5 exposure on CYP450 promoter methylation and global methylation levels in WT and KO mice. In WT and KO mice in the PM_2.5 exposure chamber, among the methylation sites examined in the CYP2E1 promoter, the CpG2 methylation level showed an opposite trend with CYP2E1 mRNA expression. The same relationship was evident between CpG3 unit methylation in the CYP1A1 promoter and CYP1A1 mRNA expression, and between CpG1 unit methylation in the CYP2S1 promoter and CYP2S1 mRNA expression. This data suggests that methylation of these CpG units regulates the expression of the corresponding gene. After exposure to PM_2.5, the expression of the DNA methylation markers ten-eleven translocation 3 (TET3) and 5-hydroxymethylcytosine (5hmC) was decreased in the WT group but significantly increased in the KO group. In summary, the changes in CYP2E1, CYP1A1, and CYP2S1 expression in the PM_2.5 exposure chamber of WT and Nrf2^-/- mice might be related to the specific methylation patterns in their promoter CpG units. After exposure to PM_2.5, Nrf2 might regulate CYP2E1 expression by affecting CpG2 unit methylation and induce DNA demethylation via TET3 expression. Our study revealed the underlying mechanism for Nrf2 to regulate epigenetics after lung exposure to PM_2.5.

Integrative Analysis Identified CD38 As a Key Node That Correlates Highly with Immunophenotype, Chemoradiotherapy Resistance, And Prognosis of Head and Neck Cancer

Head and neck cancer (HNC) is mainly treated by surgery, radiotherapy, and adjuvant chemotherapy; however, the prognosis of some patients with HNC is poor because of radiotherapy and chemotherapy resistance. In recent years, anti‑PD‑1 monoclonal antibodies have shown certain efficacy, and a change of the tumor immune microenvironment is the main reason for the failure of HNC immunotherapy. The present study aimed to identify and verify that CD38, which is closely related to the prognosis of HNC, is a potential biological marker of radiotherapy and chemotherapy resistance and PD-L1 immunotherapy resistance via a comprehensive bioinformatic analysis in The Cancer Genome Atlas and Gene Expression Omnibus databases. According to the UALCAN database, the transcript level of CD38 in HNC was analyzed using cluster analysis, and the expression of CD38 mRNA in HNC was detected using the Oncomine database. The characteristics of CD38-related oncogenes were identified by gene cluster enrichment analysis in LinkedOmics. The R2 and SEER databases were used to further evaluate the prognostic significance of the CD38 gene in HNC using receiver operating characteristic curve analysis of Kaplan-Meier (KM) survival and the clinical characteristics of the subjects. The protein-protein interaction network of the top 50 genes showing significant positive correlations with CD38 in HNC was analyzed using STRING. Finally, we used a nasopharyngeal carcinoma (NPC) cell line to verify the biological function. The results showed that the levels of CD38 mRNA expression in patients with HNC were significantly higher than those in healthy controls. The levels of CD38 mRNA expression in patients with HNC of different ages, sexes, and races were significantly higher than those in the healthy controls. CD38 is an independent prognostic factor for HNC, and high expression of CD38 indicates poor prognosis. CD38 expression correlated positively with the markers of many kinds of immune cells, and correlated significantly with the expression of PD-L1. We found that the high expression of CD38 suggested a poor prognosis in the subgroup of tumors treated with chemotherapeutic drugs in the G1/S phase. We used HNC cell lines to verify that the high expression of CD38 promoted the proliferation of NPC cells and produced radiotherapy tolerance. Through comprehensive bioinformatics analysis, we suggested that CD38 is a key gene involved in radiotherapy, chemotherapy, and immune drug resistance in HNC. This study provides a reliable biomarker to predict the prognosis of patients with HNC and a reference for clinical comprehensive treatment of HNC. Individualization combined with CD38 monoclonal antibodies might provide a promising treatment strategy for this fatal disease, and this comprehensive treatment might reduce the damage to normal tissue and improve the prognosis and quality of life of patients with HNC.

Nrf2 affects hydroquinone-induces cell cycle arrest through the p16/pRb signaling pathway and antioxidant enzymes

Hydroquinone (HQ), a well-known carcinogenic agent, induces oxidative stress, cell cycle arrest, apoptosis, and malignant transformation. As an antioxidant actor, the nuclear factor erythroid 2-related factor 2 (Nrf2) drives adaptive cellular protection in response to oxidative stress. The human lymphoblastoid cell line (TK6 cells) is widely used as a model for leukemia researches. In the present study, we focused on exploring whether Nrf2 regulatory cell cycle in TK6 cells upon HQ treatment and the underlying mechanisms. The results showed that the cell cycle arrest in TK6 cells induced by hydroquinone was accompanied by activation of the Nrf2 signaling pathway. We further clarified that Nrf2 loss accelerated cell cycle progression from G0/G1 to S and G2/M phases and promoted ROS production by downregulating the expression of SOD and GSH. Western blotting analysis indicated that Nrf2 regulated cell cycle progression via p16/pRb signaling pathways. Therefore, we conclude that Nrf2 is engaged in HQ-induced cell cycle arrest as well through p16/pRb and antioxidant enzymes.

NMN ameliorated radiation induced damage in NRF2-deficient cell and mice via regulating SIRT6 and SIRT7

Risk of cancer often increases with aging, and radiotherapy is an essential component of treatment. As for abdominal and pelvic cancer, radiotherapy always inevitably causes injury to intestines through direct DNA damage or overload of reactive oxygen species (ROS). Nuclear factor erythroid 2-related factor 2 (NRF2) has been identified as a key protective factor against ionizing-radiation induced damage through promoting DNA damage repair and antioxidant modulation. However, the level of NRF2 always decreases with aging. Here, we demonstrated that NRF2 deficiency aggravated cellular DNA damage and the intestinal pathological lesion. Overexpression of SIRT6 or SIRT7 could improve cell proliferation and protect against radiation injury in NRF2 knock-out (KO) cells by modulating oxidative-stress and DNA damage repair. Consistently, supplement of nicotinamide mononucleotide (NMN), the agonist of sirtuins, increased the level of SIRT6 and SIRT7 in NRF2 KO cells, concomitant with reduced cellular ROS level and ameliorated DNA damage. In vivo, long-term oral administration of NMN attenuated the radiation-induced injury of jejunum, increased the number of intestinal stem cells, and promoted the ability of intestinal proliferation in NRF2-/- mice. Together, our results indicated that SIRT6 and SIRT7 had involved in scavenging ROS and repairing DNA damage, and NMN could be a promising candidate for preventing radiation damage when NRF2 is lacking.

AGuIX nanoparticles enhance ionizing radiation-induced ferroptosis on tumor cells by targeting the NRF2-GPX4 signaling pathway

In the frame of radiotherapy treatment of cancer, radioresistance remains a major issue that still needs solutions to be overcome. To effectively improve the radiosensitivity of tumors and reduce the damage of radiation to neighboring normal tissues, radiosensitizers have been given increasing attention in recent years. As nanoparticles based on the metal element gadolinium, AGuIX nanoparticles have been shown to increase the radiosensitivity of cancers. Although it is a rare nanomaterial that has entered preclinical trials, the unclear biological mechanism hinders its further clinical application. In this study, we demonstrated the effectiveness of AGuIX nanoparticles in the radiosensitization of triple-negative breast cancer. We found that AGuIX nanoparticles increased the level of DNA damage by compromising the homologous recombination repair pathway instead of the non-homologous end joining pathway. Moreover, the results showed that AGuIX nanoparticles induced apoptosis, but the degree of apoptosis ability was very low, which cannot fully explain their strong radiosensitizing effect. Ferroptosis, the other mode of cell death, was also discovered to play a significant role in radiation sensitization, and AGuIX nanoparticles may regulate the anti-ferroptosis system by inhibiting the NRF2-GSH-GPX4 signaling pathway.

Supramolecular Hydrogel-Wrapped Gingival Mesenchymal Stem Cells in Cutaneous Radiation Injury

Radiation-induced skin wound/dermatitis is one of the common side effects of radiotherapy or interventional radiobiology. Gingiva-derived mesenchymal stem cells (GMSCs) were indicated to have therapeutic potentials in skin diseases. However, stem cells are prone to spread and difficult to stay in the skin for a long time, limiting their curative effects and application. This study investigated the therapeutic efficacy of Nap-GDFDFpDY (pY-Gel) self-assembled peptide hydrogel-encapsulated GMSCs to treat ¹³⁷Cs γ-radiation-induced skin wounds in mice. The effects were evaluated by skin damage score, hind limb extension measurement and histological and immunohistochemical analysis. In vivo studies showed that pY-Gel self-assembled peptide hydrogel-encapsulated GMSCs could effectively improve wound healing in irradiated skin tissues. In addition, it was found that GMSCs conditioned medium (CM) could promote the proliferation, migration and DNA damage repair ability of skin cells after irradiation in human keratinocyte cell line HaCaT and normal human dermal fibroblasts (HFF). Mechanistically, GMSCs-CM can promote the expression of epidermal growth factor receptor (EGFR), signal transducers and activators of transcription 3 (STAT3) and matrix metalloproteinases (MMPs), suggesting that activation of the EGFR/STAT3 signaling pathway may be involved in the repair of skin cells after exposure to radiations. In conclusion, pY-Gel self-assembled peptide hydrogel-encapsulated GMSCs have a beneficial therapeutic effect on radiation-induced cutaneous injury and may serve as a basis of novel cells therapeutic approach.

NRF2 Mediates Cellular Resistance to Transformation, Radiation, and Inflammation in Mice

Nuclear factor erythroid 2-related factor 2 (NRF2) is recognized as a master transcription factor that regulates expression of numerous detoxifying and antioxidant cytoprotective genes. In fact, models of NRF2 deficiency indicate roles not only in redox regulation, but also in metabolism, inflammatory/autoimmune disease, cancer, and radioresistancy. Since ionizing radiation (IR) generates reactive oxygen species (ROS), it is not surprising it activates NRF2 pathways. However, unexpectedly, activation is often delayed for many days after the initial ROS burst. Here, we demonstrate that, as assayed by γ-H2AX staining, rapid DNA double strand break (DSB) formation by IR in primary mouse Nrf2-/- MEFs was not affected by loss of NRF2, and neither was DSB repair to any great extent. In spite of this, basal and IR-induced transformation was greatly enhanced, suggesting that NRF2 protects against late IR-induced genomic instability, at least in murine MEFs. Another possible IR- and NRF2-related event that could be altered is inflammation and NRF2 deficiency increased IR-induced NF-κB pro-inflammatory responses mostly late after exposure. The proclivity of NRF2 to restrain inflammation is also reflected in the reprogramming of tumor antigen-specific lymphocyte responses in mice where Nrf2 k.o. switches Th2 responses to Th1 polarity. Delayed NRF2 responses to IR may be critical for the immune transition from prooxidant inflammation to antioxidant healing as well as in driving cellular radioresistance and survival. Targeting NRF2 to reprogram immunity could be of considerable therapeutic benefit in radiation and immunotherapy.

Nrf2 protects against radiation-induced oral mucositis via antioxidation and keratin layer thickening

Radiation-induced oral mucositis is one of the most common adverse events in radiation therapy for head and neck cancers, but treatments for oral mucositis are limited to palliative and supportive care. New approaches are required to prevent radiation-induced mucositis and to improve treatments. The Keap1-Nrf2 system regulates cytoprotection against oxidative and electrophilic stresses. Nrf2 also regulates keratin layer thickness in mouse tongues. Therefore, we hypothesized that Nrf2 may protect the tongue epithelium against radiation-induced mucositis via elimination of reactive oxygen species and induction of keratin layer thickening. To test this hypothesis, we prepared a system for γ-ray exposure of restricted areas and irradiated the tongues of model mice with Nrf2 and Keap1 loss-of-function. We discovered that loss of Nrf2 expression indeed sensitized the tongue epithelium to radiation-induced ulcer formation with inflammation. Constitutive Nrf2 activation by genetic Keap1 knockdown alleviated radiation-induced DNA damage by increasing antioxidation. In agreement with the genetic Nrf2 activation model, the Nrf2 inducer CDDO-Im prevented irradiation damage to the tongue epithelium. These results demonstrate that Nrf2 activation has the potential to prevent the development of radiation-induced mucositis and that Nrf2 inducers are an important therapeutic drug for protection of the upper aerodigestive tract from radiation-induced mucositis.

Activation of the JNKs/ATM-p53 axis is indispensable for the cytoprotection of dermal fibroblasts exposed to UVB radiation

Although UVB radiation is mainly absorbed by the epidermis, ~5-10% of its photons reach and affect the upper part of the dermis. Physiologically relevant UVB doses, able to provoke erythema, induce apoptosis in human dermal fibroblasts in vitro, as well as in the dermis of SKH-1 mice. Given the sparse and even contradictory existing information on the effect of UVB radiation on dermal fibroblasts' viability, aim of this work was to unravel the crucial signaling pathways regulating the survival of UVB-treated human dermal fibroblasts. We found that UVB radiation immediately stimulates the phosphorylation of MAPK family members, as well as Akt, and is genotoxic leading to the delayed ATM-p53 axis activation. Akt phosphorylation after UVB radiation is EGFR-mediated and EGFR inhibition leads to a further decrease of viability, while the Akt activator SC79 rescues fibroblasts to an extent by a mechanism involving Nrf2 activation. The known Nrf2 activator sulforaphane also exerts a partial protective effect, although by acting in a distinct mechanism from SC79. On the other hand, inhibition of JNKs or of the ATM-p53 axis leads to a complete loss of viability after UVB irradiation. Interestingly, JNKs activation is necessary for p53 phosphorylation, while the ATM-p53 pathway is required for the long-term activation of JNKs and Akt, reassuring the protection from UVB. Although UVB radiation results in intense and prolonged increase of intracellular ROS levels, classical anti-oxidants, such as Trolox, are unable to affect Akt, JNKs, or p53 phosphorylation and to reverse the loss of fibroblasts' viability. Collectively, here we provide evidence that the main viability-regulating UVB-triggered biochemical pathways act synergistically towards the protection of human dermal fibroblasts, with EGFR/Akt and Nrf2 serving as auxiliary anti-apoptotic machineries, while JNKs/ATM-p53 activation and interplay being overriding and indispensable for the perpetuation of cellular defense and the maintenance of cell viability.

LncRNA CTBP1-DT-encoded microprotein DDUP sustains DNA damage response signalling to trigger dual DNA repair mechanisms

Sustaining DNA damage response (DDR) signalling via retention of DDR factors at damaged sites is important for transmitting damage-sensing and repair signals. Herein, we found that DNA damage provoked the association of ribosomes with IRES region in lncRNA CTBP1-DT, which overcame the negative effect of upstream open reading frames (uORFs), and elicited the novel microprotein DNA damage-upregulated protein (DDUP) translation via a cap-independent translation mechanism. Activated ATR kinase-mediated phosphorylation of DDUP induced a drastic 'dense-to-loose' conformational change, which sustained the RAD18/RAD51C and RAD18/PCNA complex at damaged sites and initiated RAD51C-mediated homologous recombination and PCNA-mediated post-replication repair mechanisms. Importantly, treatment with ATR inhibitor abolished the effect of DDUP on chromatin retention of RAD51C and PCNA, thereby leading to hypersensitivity of cancer cells to DNA-damaging chemotherapeutics. Taken together, our results uncover a plausible mechanism underlying the DDR sustaining and might represent an attractive therapeutic strategy in improvement of DNA damage-based anticancer therapies.

Mechanisms used by cancer cells to tolerate drug-induced replication stress

Activation of oncogenes in cancer cells forces cell proliferation, leading to DNA replication stress (RS). As a consequence, cancer cells heavily rely on the intra S-phase checkpoint for survival. This fundamental principle formed the basis for the development of inhibitors against key players of the intra S-phase checkpoint, ATR and CHK1. These drugs are often combined with chemotherapeutic drugs that interfere with DNA replication to exacerbate RS and exhaust the intra S-phase checkpoint in cancer cells. However, drug resistance impedes efficient clinical use, suggesting that some cancer cells tolerate severe RS. In this review, we describe how an increased nucleotide pool, boosted stabilization and repair of stalled forks and firing of dormant origins fortify the RS response in cancer cells. Notably, the vast majority of the genes that confer RS tolerance are regulated by the E2F and NRF2 transcription factors. These transcriptional programs are frequently activated in cancer cells, allowing simultaneous activation of multiple tolerance avenues. We propose that the E2F and NRF2 transcriptional programs can be used as biomarker to select patients for treatment with RS-inducing drugs and as novel targets to kill RS-tolerant cancer cells. Together, this review aims to provide a framework to maximally exploit RS as an Achilles' heel of cancer cells.

GSTM3 deficiency impedes DNA mismatch repair to promote gastric tumorigenesis via CAND1/NRF2-KEAP1 signaling

Gastric cancer (GC) is one of the most severe gastric diseases worldwide. However, the molecular basis that drives tumorigenesis and progression is not completely understood, which hinders the efficacy and development of therapeutic options. Glutathione-S-transferases (GSTs) are a group of phase II detoxification enzymes that maintain redox homeostasis; however, their roles in cancers are not well defined. Here, we revealed that the expression of GST family members is significantly impaired in GC tissues. Glutathione-S-transferase mu 3 (GSTM3), a member of GST family, is dramatically downregulated in cancerous tissues and has been identified as an independent prognostic factor in GC associated with tumor differentiation, inhibiting GC cell proliferation and migration in vitro and in vivo. Mechanistically, GSTM3 is transcriptionally activated by NRF2/KEAP1 signaling. As a feedback loop, GSTM3 binds to Cullin-associated and neddylation-dissociated 1 protein (CAND1), an exchange factor for integrating Kelch-like ECH-associated protein 1 (KEAP1) into Cul3-RING ubiquitin ligases (CRL3), to disrupt nuclear factor-erythroid factor 2-related factor 2 (NRF2)/KEAP1 binding and prevent NRF2 ubiquitination and degradation, leading to its activation. A deficiency in glutathione S-Transferase Mu 3 (GSTM3) reduces DNA mismatch repair (MMR) gene expression and increases mutagenesis via CAND1/NRF2 binding. Importantly, GSTM3/NRF2 and KEAP1 were negatively and positively associated with the genomic signature for microsatellite instability, respectively. Clinically, GSTM3, NRF2, and MutS homolog 6 (MSH6) were positively correlated in the GC specimens. This study uncovered a reciprocal regulation between GSTM3 and NRF2 and established a functional and clinical link between GSTM3-NRF2/KEAP1 and MMR during GC cell proliferation and progression, thus providing potential therapeutic targets for GC.

Mechanisms of Action of Ozone Therapy in Emerging Viral Diseases: Immunomodulatory Effects and Therapeutic Advantages With Reference to SARS-CoV-2

Medical oxygen-ozone (O₂-O₃) is a successful therapeutic approach accounting on the assessed beneficial action of ozone in the range 30–45 μg/ml (expanded range 10–80 μg/ml according to different protocols), as in this dosage range ozone is able to trigger a cellular hormetic response via the modulating activity of reactive oxygen species (ROS), as signaling molecules. The ozone-dependent ROS-mediated fatty acid oxidation leads to the formation of lipid ozonization products (LOPs), which act as signal transducers by triggering ROS signaling and therefore mitohormetic processes. These processes ultimately activate survival mechanisms at a cellular level, such as the Nrf2/Keap1/ARE system activation, the AMPK/FOXO/mTOR/Sir1 pathway and the Nrf2/NF-kB cross talk. Furthermore, indirectly, via these pathways, LOPs trigger the HIF-1α pathway, the HO-1 signaling and the NO/iNOS biochemical machinery. Ozone-driven shift of cytokine activation pathways, from pro-inflammatory to anti-inflammatory immediately afterwards, also exert direct immunoregulatory effects on regulatory T lymphocytes as well as on the intestinal microbiota, which in turn can affect immune response thus influencing the progression of the disease. In this review, we will describe the biological and biochemical mechanisms of action of ozone therapy with the aim of evaluating both positive and critical aspects of ozone use as a therapeutic adjuvant in the light of emerging viral infections, such as SARS-CoV-2 and microbiome-associated disorders related to SARS-CoV-2.

Dietary Phytochemicals Targeting Nrf2 to Enhance the Radiosensitivity of Cancer

Nowadays, cancer has become the second leading cause of death worldwide. Radiotherapy (RT) is the mainstay in management of carcinoma; however, overcoming radioresistance remains a great challenge to successfully treat cancer. Nrf2 is a key transcription factor that is responsible for maintaining cellular redox homeostasis. Activation of Nrf2 signaling pathway could upregulate multifarious antioxidant and detoxifying enzymes, further scavenging excessive reactive oxygen species (ROS). Despite its cytoprotective roles in normal cells, it could also alleviate oxidative stress and DNA damage caused by RT in cancer cells, thus promoting cancer cell survival. Accumulating evidence indicates that overactivation of Nrf2 is associated with radioresistance; therefore, targeting Nrf2 is a promising strategy to enhance radiosensitivity. Dietary phytochemicals coming from natural products are characterized by low cost, low toxicity, and general availability. Numerous phytochemicals are reported to regulate Nrf2 and intensify the killing capability of RT through diverse mechanisms, including promoting oxidative stress, proapoptosis, and proautophagy as well as inhibiting Nrf2-mediated cytoprotective genes expression. This review summarizes recent advances in radiosensitizing effects of dietary phytochemicals by targeting Nrf2 and discusses the underlying mechanisms, including N6-methyladenosine (m6A) modification of Nrf2 mediated by phytochemicals in cancer.

The potential roles of Nrf2/Keap1 signaling in anticancer drug interactions

Nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2), together with its suppressive binding partner Kelch-like ECH-associated protein 1 (Keap1), regulates cellular antioxidant response and drug metabolism. The roles of Nrf2/Keap1 signaling in the pathology of many diseases have been extensively investigated, and small molecules targeting Nrf2/Keap1 signaling have been developed to prevent or treat diseases such as multiple sclerosis, chronic kidney disease and cancer. Notably, Nrf2 plays dual roles in cancer development and treatment. Activation of Nrf2/Keap1 signaling in cancer cells has been reported to promote cancer progression and result in therapy resistance. Since cancer patients are often suffering comorbidities of other chronic diseases, anticancer drugs could be co-administrated with other drugs and herbs. Nrf2/Keap1 signaling modulators, especially activators, are common in drugs, herbs and dietary ingredients, even they are developed for other targets. Therefore, drug-drug or herb-drug interactions due to modulation of Nrf2/Keap1 signaling should be considered in cancer therapies. Here we briefly summarize basic biochemistry and physiology functions of Nrf2/Keap1 signaling, Nrf2/Keap1 signaling modulators that cancer patients could be exposed to, and anticancer drugs that are sensitive to Nrf2/Keap1 signaling, aiming to call attention to the potential drug-drug or herb-drug interactions between anticancer drugs and these Nrf2/Keap1 signaling modulators.

An Overview of the Nrf2/ARE Pathway and Its Role in Neurodegenerative Diseases

Nrf2 is a basic region leucine-zipper transcription factor that plays a pivotal role in the coordinated gene expression of antioxidant and detoxifying enzymes, promoting cell survival in adverse environmental or defective metabolic conditions. After synthesis, Nrf2 is arrested in the cytoplasm by the Kelch-like ECH-associated protein 1 suppressor (Keap1) leading Nrf2 to ubiquitin-dependent degradation. One Nrf2 activation mechanism relies on disconnection from the Keap1 homodimer through the oxidation of cysteine at specific sites of Keap1. Free Nrf2 enters the nucleus, dimerizes with small musculoaponeurotic fibrosarcoma proteins (sMafs), and binds to the antioxidant response element (ARE) sequence of the target genes. Since oxidative stress, next to neuroinflammation and mitochondrial dysfunction, is one of the hallmarks of neurodegenerative pathologies, a molecular intervention into Nrf2/ARE signaling and the enhancement of the transcriptional activity of particular genes are targets for prevention or delaying the onset of age-related and inherited neurogenerative diseases. In this study, we review evidence for the Nrf2/ARE-driven pathway dysfunctions leading to various neurological pathologies, such as Alzheimer’s, Parkinson’s, and Huntington’s diseases, as well as amyotrophic lateral sclerosis, and the beneficial role of natural and synthetic molecules that are able to interact with Nrf2 to enhance its protective efficacy.

Design, Synthesis, and Biological Evaluation of a Novel Aminothiol Compound as Potential Radioprotector

The risk of radiation damage has increased with the rapid development of nuclear technology and radiotherapy. Hence, research on radioprotective agents is of utmost importance. In the present study, a novel aminothiol compound 12, containing a linear alkylamino backbone and three terminal thiols, was synthesized. Owing to the appropriate capped groups in the chains, it has an improved permeability and oral bioavailability compared to other radioprotective agents. Oral administration of compound 12 improved the survival of mice that received lethal doses of γ-irradiation. Experimental results demonstrated that compound 12 not only mitigated total body irradiation-induced hematopoietic injury by increasing the frequencies of hematopoietic stem and progenitor cells but also prevented abdominal irradiation-induced intestinal injury by increasing the survival of Lgr5⁺ intestinal cells, lysozyme⁺ Paneth cells, and Ki67⁺ cells. In addition, compound 12 decreased oxidative stress by upregulating the expression of Nrf2 and NQO1 and downregulating the expression of NOX1. Further, compound 12 inhibited γ-irradiation-induced DNA damage and alleviated G2/M phase arrest. Moreover, compound 12 decreased the levels of p53 and Bax and increased the level of Bcl-2, demonstrating that it may suppress radiation-induced apoptosis via the p53 pathway. These results indicate that compound 12 has the possibility of preventing radiation injury and can be a potential radioprotector for clinical applications.

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.

Inhibition of the NRF2/KEAP1 Axis: A Promising Therapeutic Strategy to Alter Redox Balance of Cancer Cells

Significance: The nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (NRF2/KEAP1) pathway is a crucial and highly conserved defensive system that is required to maintain or restore the intracellular homeostasis in response to oxidative, electrophilic, and other types of stress conditions. The tight control of NRF2 function is maintained by a complex network of biological interactions between positive and negative regulators that ultimately ensure context-specific activation, culminating in the NRF2-driven transcription of cytoprotective genes. Recent Advances: Recent studies indicate that deregulated NRF2 activation is a frequent event in malignant tumors, wherein it is associated with metabolic reprogramming, increased antioxidant capacity, chemoresistance, and poor clinical outcome. On the other hand, the growing interest in the modulation of the cancer cells' redox balance identified NRF2 as an ideal therapeutic target. Critical Issues: For this reason, many efforts have been made to identify potent and selective NRF2 inhibitors that might be used as single agents or adjuvants of anticancer drugs with redox disrupting properties. Despite the lack of specific NRF2 inhibitors still represents a major clinical hurdle, the researchers have exploited alternative strategies to disrupt NRF2 signaling at different levels of its biological activation. Future Directions: Given its dualistic role in tumor initiation and progression, the identification of the appropriate biological context of NRF2 activation and the specific clinicopathological features of patients cohorts wherein its inactivation is expected to have clinical benefits, will represent a major goal in the field of cancer research. In this review, we will briefly describe the structure and function of the NRF2/ KEAP1 system and some of the most promising NRF2 inhibitors, with a particular emphasis on natural compounds and drug repurposing. Antioxid. Redox Signal. 34, 1428-1483.

Brusatol Inhibits Tumor Growth and Increases the Efficacy of Cabergoline against Pituitary Adenomas

Cabergoline (CAB) is the first choice for treatment of prolactinoma and the most common subtype of pituitary adenoma. However, drug resistance and lack of effectiveness in other pituitary tumor types remain clinical challenges to this treatment. Brusatol (BT) is known to inhibit cell growth and promote apoptosis in a variety of cancer cells. In our present studies, we investigate the effects of BT on pituitary tumor cell proliferation in vitro and in vivo. BT treatment resulted in an increase in Annexin V-expressing cells and promoted the expression of apoptosis-related proteins in rat and human pituitary tumor cells. Investigation of the mechanism underlying this effect revealed that BT increased the production of reactive oxygen species (ROS) and inhibited the phosphorylation of 4EBP1 and S6K1. Furthermore, treatment with a combination of BT and CAB resulted in greater antitumor effects than either treatment alone in nude mice and pituitary tumor cells. Collectively, our results suggest that the BT-induced ROS accumulation and inhibition of mTORC1 signaling pathway leads to inhibition of tumor growth. Combined use of CAB and BT may increase the clinical effectiveness of treatment for human pituitary adenomas.

Stabilization of Nrf2 leading to HO-1 activation protects against zinc oxide nanoparticles-induced endothelial cell death

With the abundant production and wide application of zinc oxide nanoparticles (ZnONPs), the potential health risks of ZnONPs have raised serious concerns. Oxidative stress is recognized as the most important outcome of the toxicity induced by ZnONPs. The Nrf2-Keap1 system and its downstream antioxidative genes are the fundamental protective mechanisms for redox hemeostasis. However, the detailed mechanisms of Nrf2 activation in ZnONPs-treated endothelial cells and murine blood vessels have yet to be elucidated. Herein, we show that Nrf2 was activated and played a negative role in cell death induced by ZnONPs. Moreover, we demonstrate that HO-1 was the most extensively upregulated antioxidative gene-activated by Nrf2. Forced overexpression of HO-1, pharmacological activation of HO-1 with the agonists RTA-408 (omaveloxolone, an FDA-approved drug) and RTA-402 repressed cell death, and treatment with HO-1 antagonist SnPP exacerbated the cell death. Importantly, loss of HO-1 diminished the cytoprotective role induced by Nrf2 in ZnONPs-treated HUVEC cells, indicating that the Nrf2-HO-1 axis was the crucial regulatory mechanism for the antioxidative response in the context of ZnONPs-induced endothelial damage. Mechanistically, we demonstrate that the p62-Keap1 axis was not involved in the activation of Nrf2. Intriguingly, the degradation half-life of Nrf2 in HUVEC cells was increased from less than 1 h under quiescent conditions to approximately 6 h under ZnONPs treatment condition; moreover, ZnONPs treatment induced activation of Nrf2/HO-1 and accumulation of ubiquitin in the aorta ventralis of mouse, suggesting that the ubiquitin-proteasome system had been perturbed, which subsequently led to the stabilization of Nrf2 and activation of HO-1. This study might contribute to a better understanding of ZnONPs-associated toxicity.

LINC-PINT impedes DNA repair and enhances radiotherapeutic response by targeting DNA-PKcs in nasopharyngeal cancer

Radioresistance continues to be the leading cause of recurrence and metastasis in nasopharyngeal cancer. Long noncoding RNAs are emerging as regulators of DNA damage and radioresistance. LINC-PINT was originally identified as a tumor suppressor in various cancers. In this study, LINC-PINT was significantly downregulated in nasopharyngeal cancer tissues than in rhinitis tissues, and low LINC-PINT expressions showed poorer prognosis in patients who received radiotherapy. We further identified a functional role of LINC-PINT in inhibiting the malignant phenotypes and sensitizing cancer cells to irradiation in vitro and in vivo. Mechanistically, LINC-PINT was responsive to DNA damage, inhibiting DNA damage repair through ATM/ATR-Chk1/Chk2 signaling pathways. Moreover, LINC-PINT increased radiosensitivity by interacting with DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and negatively regulated the expression and recruitment of DNA-PKcs. Therefore, these findings collectively support the possibility that LINC-PINT serves as an attractive target to overcome radioresistance in NPC.

Anti-Angiogenic Therapy: Current Challenges and Future Perspectives

Anti-angiogenic therapy is an old method to fight cancer that aims to abolish the nutrient and oxygen supply to the tumor cells through the decrease of the vascular network and the avoidance of new blood vessels formation. Most of the anti-angiogenic agents approved for cancer treatment rely on targeting vascular endothelial growth factor (VEGF) actions, as VEGF signaling is considered the main angiogenesis promotor. In addition to the control of angiogenesis, these drugs can potentiate immune therapy as VEGF also exhibits immunosuppressive functions. Despite the mechanistic rational that strongly supports the benefit of drugs to stop cancer progression, they revealed to be insufficient in most cases. We hypothesize that the rehabilitation of old drugs that interfere with mechanisms of angiogenesis related to tumor microenvironment might represent a promising strategy. In this review, we deepened research on the molecular mechanisms underlying anti-angiogenic strategies and their failure and went further into the alternative mechanisms that impact angiogenesis. We concluded that the combinatory targeting of alternative effectors of angiogenic pathways might be a putative solution for anti-angiogenic therapies.

MiR-582-5p Inhibits Bladder Cancer-Genesis by Suppressing TTK Expression

BACKGROUND

Bladder cancer (BC) refers to the malignant growth found in the cells and tissues of the urinary bladder. While many studies have researched the progression of BC, scientists are yet to fully understand the mechanism of BC. This research aimed to explore the role of miR-582-5p and its target gene TTK in BC pathogenesis.

METHODS

The evaluation of miR-582-5p and TTK mRNA expression in BC tissues or cells was performed using qRT-PCR. TargetScan was then used to predict the binding site of miR-582-5p on TTK mRNA. Subsequently, dual-luciferase reporter and RNA pull-down assays were employed to validate the binding relationship between miR-582-5p and TTK mRNA. CCK-8, BrdU, flow cytometry, and caspase-3 activity assays were later conducted to evaluate the viability, proliferation, cell cycle, and apoptosis of BC cells.

RESULTS

Investigations revealed that miR-582-5p was downregulated in BC tissues and cells. Meanwhile, miR-582-5p inhibited the viability and proliferation of BC cells while stimulating the apoptosis and cycle arrest of the cells. TTK, the target gene of miR-582-5p, was later found to be over-expressed in BC tissues and cells. TTK, however, was observed to exhibit an opposite effect on miR-582-5p. Simply put, it stimulated BC cell malignant phenotypes, and this stimulation could be directly reversed by miR-582-5p.

CONCLUSION

This research confirmed that miR-582-5p could restrain bladder carcinogenesis by inhibiting TTK expression.