Nrf2-miR-129-3p-mTOR Axis Controls an miRNA Regulatory Network Involved in HDACi-Induced Autophagy

miR-129 Regulates Yak Intramuscular Preadipocyte Proliferation and Differentiation through the PI3K/AKT Pathway

miR-129 plays a crucial role in regulating various cellular processes, including adipogenesis; however, its downstream molecular mechanisms remain unclear. In this study, we demonstrated that miR-129 promotes yak adipogenesis in vitro via the PI3K/AKT pathway. Overexpression and interference of miR-129 in yak intramuscular preadipocytes (YIMAs) enhanced and inhibited cell differentiation, respectively, with corresponding changes in cell proliferation. Further investigation revealed that miR-129 enhances AKT and p-AKT activity in the AKT pathway without affecting cell apoptosis, and a specific inhibitor (LY294002) was used to confirm that miR-129 regulates YIMAs proliferation and differentiation through the PI3K/AKT pathway. Our findings suggest that miR-129 promotes yak adipogenesis by enhancing PI3K/AKT pathway activity. This study provides the foundation to precisely elucidate the molecular mechanism of miR-129 in YIMAs adipogenesis and develop advanced miRNA-based strategies to improve meat nutrition and obesity-related ailments in beef production.

Regulatory miRNAs in cancer cell recovery from therapy exposure and its implications as a novel therapeutic strategy for preventing disease recurrence

The desired outcome of cancer therapies is the eradication of disease. This can be achieved when therapy exposure leads to therapy-induced cancer cell death as the dominant outcome. Theoretically, a permanent therapy-induced growth arrest could also contribute to a complete response, which has the potential to lead to remission. However, preclinical models have shown that therapy-induced growth arrest is not always durable, as recovering cancer cell populations can contribute to the recurrence of cancer. Significant research efforts have been expended to develop strategies focusing on the prevention of recurrence. Recovery of cells from therapy exposure can occur as a result of several cell stress adaptations. These include cytoprotective autophagy, cellular quiescence, a reversable form of senescence, and the suppression of apoptosis and necroptosis. It is well documented that microRNAs regulate the response of cancer cells to anti-cancer therapies, making targeting microRNAs therapeutically a viable strategy to sensitization and the prevention of recovery. We propose that the use of microRNA-targeting therapies in prolonged sequence, that is, a significant period after initial therapy exposure, could reduce toxicity from the standard combination strategy, and could exploit new epigenetic states essential for cancer cells to recover from therapy exposure. In a step toward supporting this strategy, we survey the available scientific literature to identify microRNAs which could be targeted in sequence to eliminate residual cancer cell populations that were arrested as a result of therapy exposure. It is our hope that by successfully identifying microRNAs which could be targeted in sequence we can prevent disease recurrence.

An update on the bridging factors connecting autophagy and Nrf2 antioxidant pathway

Macroautophagy/autophagy is a lysosome-dependent catabolic pathway for the degradation of intracellular proteins and organelles. Autophagy dysfunction is related to many diseases, including lysosomal storage diseases, cancer, neurodegenerative diseases, cardiomyopathy, and chronic metabolic diseases, in which increased reactive oxygen species (ROS) levels are also observed. ROS can randomly oxidize proteins, lipids, and DNA, causing oxidative stress and damage. Cells have developed various antioxidant pathways to reduce excessive ROS and maintain redox homeostasis. Treatment targeting only one aspect of diseases with autophagy dysfunction and oxidative stress shows very limited effects. Herein, identifying the bridging factors that can regulate both autophagy and antioxidant pathways is beneficial for dual-target therapies. This review intends to provide insights into the current identified bridging factors that connect autophagy and Nrf2 antioxidant pathway, as well as their tight interconnection with each other. These factors could be potential dual-purpose targets for the treatment of diseases implicated in both autophagy dysfunction and oxidative stress.

Dimethyl Fumarate and Intestine: From Main Suspect to Potential Ally against Gut Disorders

Dimethyl fumarate (DMF) is a well-characterized molecule that exhibits immuno-modulatory, anti-inflammatory, and antioxidant properties and that is currently approved for the treatment of psoriasis and multiple sclerosis. Due to its Nrf2-dependent and independent mechanisms of action, DMF has a therapeutic potential much broader than expected. In this comprehensive review, we discuss the state-of-the-art and future perspectives regarding the potential repurposing of DMF in the context of chronic inflammatory diseases of the intestine, such as inflammatory bowel disorders (i.e., Crohn's disease and ulcerative colitis) and celiac disease. DMF's mechanisms of action, as well as an exhaustive analysis of the in vitro/in vivo evidence of its beneficial effects on the intestine and the gut microbiota, together with observational studies on multiple sclerosis patients, are here reported. Based on the collected evidence, we highlight the new potential applications of this molecule in the context of inflammatory and immune-mediated intestinal diseases.

Autophagy orchestrates resistance in hepatocellular carcinoma cells

Treatment resistance is one of the major barriers for therapeutic strategies in hepatocellular carcinoma (HCC). Many studies have indicated that chemotherapy and radiotherapy induce autophagy machinery (cell protective autophagy) in HCC cells. In addition, many experiments report a remarkable crosstalk between treatment resistance and autophagy pathways. Thus, autophagy could be one of the key factors enabling tumor cells to hinder induced cell death after medical interventions. Therefore, extensive research on the molecular pathways involved in resistance induction and autophagy have been conducted to achieve the desired therapeutic response. The key molecular pathways related to the therapy resistance are TGF-β, MAPK, NRF2, NF-κB, and non-coding RNAs. In addition, EMT, drug transports, apoptosis evasion, DNA repair, cancer stem cells, and hypoxia could have considerable impact on the hepatoma cell's response to therapies. These mechanisms protect tumor cells against various treatments and many studies have shown that each of them is connected to the molecular pathways of autophagy induction in HCC. Hence, autophagy inhibition may be an effective strategy to improve therapeutic outcome in HCC patients. In this review, we further highlight how autophagy leads to poor response during treatment through a complex molecular network and how it enhances resistance in primary liver cancer. We propose that combinational regimens of approved HCC therapeutic protocols plus autophagy inhibitors may overcome drug resistance in HCC therapy.

Depsipeptides Targeting Tumor Cells: Milestones from In Vitro to Clinical Trials

Cancer is currently considered one of the most threatening diseases worldwide. Diet could be one of the factors that can be enhanced to comprehensively address a cancer patient's condition. Unfortunately, most molecules capable of targeting cancer cells are found in uncommon food sources. Among them, depsipeptides have emerged as one of the most reliable choices for cancer treatment. These cyclic amino acid oligomers, with one or more subunits replaced by a hydroxylated carboxylic acid resulting in one lactone bond in a core ring, have broadly proven their cancer-targeting efficacy, some even reaching clinical trials and being commercialized as "anticancer" drugs. This review aimed to describe these depsipeptides, their reported amino acid sequences, determined structure, and the specific mechanism by which they target tumor cells including apoptosis, oncosis, and elastase inhibition, among others. Furthermore, we have delved into state-of-the-art in vivo and clinical trials, current methods for purification and synthesis, and the recognized disadvantages of these molecules. The information collated in this review can help researchers decide whether these molecules should be incorporated into functional foods in the near future.

Interplay between Non-Coding RNAs and NRF2 in Different Cancers: Spotlight on MicroRNAs and Long Non-Coding RNAs

Cancer is a multifactorial disease, and a wealth of information has enabled basic and clinical researchers to develop a better conceptual knowledge of the highly heterogeneous nature of cancer. Deregulations of spatio-temporally controlled transduction pathways play a central role in cancer progression. NRF2-driven signaling has engrossed significant attention because of its fundamentally unique features to dualistically regulate cancer progression. Context-dependent diametrically opposed roles of NRF2-induced signaling are exciting. More importantly, non-coding RNA (ncRNA) mediated regulation of NRF2 and interplay between NRF2 and ncRNAs have added new layers of complexity to already intricate nature of NRF2 signaling. There is a gradual enrichment in the existing pool of knowledge related to interplay between microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in different cancers. However, surprisingly, there are no clues about interplay between circular RNAs and NRF2 in various cancers. Therefore, future studies must converge on the functional characterization of additional important lncRNAs and circular RNAs, which regulated NRF2-driven signaling or, conversely, NRF2 transcriptionally controlled their expression to regulate various stages of cancer. SIGNIFICANCE STATEMENT: Recently, many researchers have focused on the NRF2-driven signaling in cancer progression. Excitingly, discovery of non-coding RNAs has added new layers of intricacy to the already complicated nature of KEAP1/NRF2 signaling in different cancers. These interactions are shaping the NRF2-driven signaling landscape, and better knowledge of these pathways will be advantageous in pharmacological modulation of non-coding RNA-mediated NRF2 signaling in various cancers.

CircRNAs: Roles in regulating head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC), the most common head and neck malignant tumor, with only monotherapy, is characterized by poor prognosis, and low 5-year survival rate. Due to the lack of therapeutic targets, the targeted drugs for HNSCC are rare. Therefore, exploring the regulation mechanism of HNSCC and identifying effective therapeutic targets will be beneficial to its treatment of. Circular RNA (CircRNA) is a class of RNA molecules with a circular structure, which is widely expressed in human body. CircRNAs regulate gene expression by exerting the function as a miRNA sponge, thereby mediating the occurrence and development of HNSCC cell proliferation, apoptosis, migration, invasion, and other processes. In addition, circRNAs are also involved in the regulation of tumor sensitivity to chemical drugs and other biological functions. In this review, we systematically listed the functions of circRNAs and explored the regulatory mechanisms of circRNAs in HNSCC from the aspects of tumor growth, cell death, angiogenesis, tumor invasion and metastasis, tumor stem cell regulation, tumor drug resistance, immune escape, and tumor microenvironment. It will assist us in discovering new diagnostic markers and therapeutic targets, while encourage new ideas for the diagnosis and treatment of HNSCC.

The Emerging Role of MicroRNAs and Autophagy Mechanism in Pancreatic Cancer Progression: Future Therapeutic Approaches

Pancreatic cancer constitutes the fourth most frequent cause of death due to malignancy in the US. Despite the new therapeutic modalities, the management of pancreatic ductal adenocarcinoma (PDAC) is considered a difficult task for clinicians due to the fact that is usually diagnosed in already advanced stages and it is relatively resistant to the current chemotherapeutic agents. The molecular background analysis of pancreatic malignant tumors, which includes various epigenetic and genetic alterations, opens new horizons for the development of novel diagnostic and therapeutic strategies. The interplay between miRNAs, autophagy pathway, and pancreatic carcinogenesis is in the spotlight of the current research. There is strong evidence that miRNAs take part in carcinogenesis either as tumor inhibitors that combat the oncogene expression or as promoters (oncomiRs) by acting as oncogenes by interfering with various cell functions such as proliferation, programmed cell death, and metabolic and signaling pathways. Deregulation of the expression levels of various miRNAs is closely associated with tumor growth, progression, and dissemination, as well as low sensitivity to chemotherapeutic agents. Similarly, autophagy despite constituting a pivotal homeostatic mechanism for cell survival has a binary role in PDAC, either as an inhibitor or promoter of carcinogenesis. The emerging role of miRNAs in autophagy gets a great deal of attention as it opens new opportunities for the development of novel therapeutic strategies for the management of this aggressive and chemoresistant malignancy. In this review, we will shed light on the interplay between miRNAs and the autophagy mechanism for pancreatic cancer development and progression.

Rapamycin improves the quality and developmental competence of mice oocytes by promoting DNA damage repair during in vitro maturation

BACKGROUND

Increasing evidence has shown that the mammalian target of rapamycin (mTOR) pathway plays a critical role in oocyte meiosis and embryonic development, however, previous studies reporting the effects of rapamycin on oocyte IVM showed different or even opposite results, and the specific mechanisms were not clear.

METHODS

The immature oocytes from female mice underwent IVM with rapamycin at different concentrations to select an optimal dose. The maturation rate, activation rate, subsequent cleavage and blastocyst formation rates, spindle assembly, chromosome alignment, mitochondrial membrane potential (MMP), ROS levels, and DNA damage levels were evaluated and compared in oocytes matured with or without rapamycin. In addition, the expression levels of genes associated with mTORC1 pathway, spindle assembly, antioxidant function, and DNA damage repair (DDR) were also assessed and compared.

RESULTS

Rapamycin at 10 nM was selected as an optimal concentration based on the higher maturation and activation rate of IVM oocytes. Following subsequent culture, cleavage and blastocyst formation rates were elevated in activated embryos from the rapamycin group. Additionally, oocytes cultured with 10 nM rapamycin presented decreased ROS levels, reduced chromosome aberration, and attenuated levels of γ-H2AX. No significant effects on the percentages of abnormal spindle were observed. Correspondingly, the expressions of Nrf2, Atm, Atr, and Prkdc in IVM oocytes were markedly increased, following the inhibition of mTORC1 pathway by 10 nM rapamycin.

CONCLUSION

Rapamycin at 10 nM could ameliorate the developmental competence and quality of IVM oocytes of mice, mainly by improving the chromosome alignments. The inhibition of mTORC1 pathway, which involved in activating DDR-associated genes may act as a potential mechanism for oocyte quality improvement by rapamycin.

The Role of Ferroptosis in the Treatment and Drug Resistance of Hepatocellular Carcinoma

Cell death is a fundamental feature of multicellular organisms’ development and a key driver of degenerative diseases. Ferroptosis is a new regulatory cell death mediated by iron-dependent lipid peroxidation, which is different from apoptosis and necrosis in morphology, pathophysiology and mechanism. Recent studies have found that ferroptosis is involved in the development of many diseases including hepatocellular carcinoma (HCC). As further research progresses, specific mechanisms of ferroptosis in HCC are being revealed. In this review, we summarize these recent advances about the treatment of drug-resistance in HCC and the latest ferroptosis-related treatment for HCC.

Virtual screening identified natural Keap1-Nrf2 PPI inhibitor alleviates inflammatory osteoporosis through Nrf2-mir214-Traf3 axis

Overactive osteoclastogenesis is involved in the inflammatory bone loss and could be target for therapy. Here, we applied transcription factor enrichment analysis using public inflammatory osteolysis datasets and identified Nrf2 as the potential therapeutic target. Additionally, in-silico screening was performed to dig out Nrf2-Keap1 PPI inhibitor and Forsythoside-β was found to be the best-performing PHG compound. We firstly tested the effect of Forsythoside-β in inflammatory osteoporosis models and found it was able to attenuate the bone loss by inhibiting osteoclastogenesis and activating Nrf2-signaling in vivo. Forsythoside-β was capable to suppress the differentiation of osteoclast in time and dose-dependent manners in vitro. Further, Forsythoside-β could inhibit the production of reactive oxygen species and induce Nrf2 nuclear-translocation by interrupting Nrf2-Keap1 PPI. Recently, Nrf2 was identified as the epigenetic regulator modulating levels of miRNA in various diseases. We discovered that Forsythoside-β could suppress the expression of mir-214-3p, one of most variable miRNAs during osteoclastogenesis. To clarify the undermining mechanism, by utilizing chip-seq dataset, we found that Nrf2 could bind to promoter of mir-214-3p and further regulate this miRNA. Collectively, Forsythoside-β was able to prevent bone loss through Nrf2-mir-214-3p-Traf3 axis, which could be a promising candidate for treating inflammatory bone loss in the future.

The Roles of Oxidative Stress in Regulating Autophagy in Methylmercury-induced Neurotoxicity

Methylmercury (MeHg) is a potential neurotoxin that is highly toxic to the human central nervous system. Although MeHg neurotoxicity has been widely studied, the mechanism of MeHg neurotoxicity has not yet been fully elucidated. Some research evidence suggests that oxidative stress and autophagy are important molecular mechanisms of MeHg-induced neurotoxicity. Researchers have widely accepted that oxidative stress regulates the autophagy pathway. The current study reviews the activation of Nuclear factor-erythroid-2-related factor (Nrf2)-related oxidative stress pathways and autophagy signaling pathways in the case of MeHg neurotoxicity. In addition, autophagy mainly plays a role in the neurotoxicity of MeHg through mTOR-dependent and mTOR-independent autophagy signaling pathways. Finally, the regulation of autophagy by reactive oxygen species (ROS) and Nrf2 in MeHg neurotoxicity was explored in this review, providing a new concept for the study of the neurotoxicity mechanism of MeHg.

The tip of the iceberg: emerging roles of TORC1, and its regulatory functions in plant cells

Target of Rapamycin (TOR) is an evolutionarily conserved protein kinase that plays a central role in coordinating cell growth with light availability, the diurnal cycle, energy availability, and hormonal pathways. TOR Complex 1 (TORC1) controls cell proliferation, growth, metabolism, and defense in plants. Sugar availability is the main signal for activation of TOR in plants, as it also is in mammals and yeast. Specific regulators of the TOR kinase pathway in plants are inorganic compounds in the form of major nutrients in the soils, and light inputs via their impact on autotrophic metabolism. The lack of TOR is embryo-lethal in plants, whilst dysregulation of TOR signaling causes major alterations in growth and development. TOR exerts control as a regulator of protein translation via the action of proteins such as S6K, RPS6, and TAP46. Phytohormones are central players in the downstream systemic physiological TOR effects. TOR has recently been attributed to have roles in the control of DNA methylation, in the abundance of mRNA splicing variants, and in the variety of regulatory lncRNAs and miRNAs. In this review, we summarize recent discoveries in the plant TOR signaling pathway in the context of our current knowledge of mammalian and yeast cells, and highlight the most important gaps in our understanding of plants that need to be addressed in the future.

MicroRNAs in the regulation of autophagy and their possible use in age-related macular degeneration therapy

Age-related macular degeneration (AMD) is a progressive sight-impairing disease of the elderly. The pathogenic mechanisms of AMD are not well understood although both genetic and many environmental factors have been associated with the development of AMD. One clinical hallmark of AMD is the detrimental aggregation of damaged proteins. Recently, it has been suggested that the weakening of autophagy clearance is an important mechanism in the pathogenesis of AMD. Autophagy is important in the removal of damaged or no longer needed cellular material and its recycling. A considerable number of autophagy-targeting microRNAs (miRNAs), small RNA molecules and epigenetic regulators have been found to be either up- or down-regulated in AMD patients and experimental models. The important role of autophagy-targeting miRNAs is supported by several studies and can open the prospect of the use of these miRNAs in the therapy for AMD.

Inhibiting autophagy enhances sulforaphane-induced apoptosis via targeting NRF2 in esophageal squamous cell carcinoma

Sulforaphane (SFN), a natural anti-tumor compound from cruciferous vegetables, has been reported to induce protective autophagy to cancer cells, which might impair the anti-tumor efficiency of SFN. However, the accurate function and mechanism of SFN inducing autophagy in cancers are still obscure, especially in esophageal squamous cell carcinoma (ESCC), one of malignancies with high incidence in North China. Here, we mainly explored the potential function of autophagy upon SFN treatment in ESCC and molecular mechanism. We demonstrated that SFN could inhibit cell proliferation and induce apoptosis by activating caspase pathway. Moreover, we found activation of NRF2 pathway by SFN was responsible for the induction of autophagy and also a disadvantage element to the anti-tumor effects of SFN on ESCC, indicating that SFN might induce protective autophagy in ESCC. We, therefore, investigated effects of autophagy inhibition on sensitivity of ESCC cells to SFN and found that chloroquine (CQ) could neutralize the activation of SFN on NRF2 and enhance the activation of SFN on caspase pathway, thus improved the anti-tumor efficiency of SFN on ESCC in vitro and in vivo. Our study provides a preclinical rationale for development of SFN and its analogs to the future treatment of ESCC.

The Keap1-Nrf2 System: A Mediator between Oxidative Stress and Aging

Oxidative stress, a term that describes the imbalance between oxidants and antioxidants, leads to the disruption of redox signals and causes molecular damage. Increased oxidative stress from diverse sources has been implicated in most senescence-related diseases and in aging itself. The Kelch-like ECH-associated protein 1- (Keap1-) nuclear factor-erythroid 2-related factor 2 (Nrf2) system can be used to monitor oxidative stress; Keap1-Nrf2 is closely associated with aging and controls the transcription of multiple antioxidant enzymes. Simultaneously, Keap1-Nrf2 signaling is also modulated by a more complex regulatory network, including phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), protein kinase C, and mitogen-activated protein kinase. This review presents more information on aging-related molecular mechanisms involving Keap1-Nrf2. Furthermore, we highlight several major signals involved in Nrf2 unbinding from Keap1, including cysteine modification of Keap1 and phosphorylation of Nrf2, PI3K/Akt/glycogen synthase kinase 3β, sequestosome 1, Bach1, and c-Myc. Additionally, we discuss the direct interaction between Keap1-Nrf2 and the mammalian target of rapamycin pathway. In summary, we focus on recent progress in research on the Keap1-Nrf2 system involving oxidative stress and aging, providing an empirical basis for the development of antiaging drugs.

MiR-449a attenuates autophagy of T-cell lymphoma cells by downregulating ATG4B expression

Increasing evidence suggests the role of miR-449a in the regulation of tumorigenesis and autophagy. Autophagy plays an important role in the malignancy of T-cell lymphoma. However, it is still unknown whether miR-449a is associated with autophagy to regulate the malignancy of T-cell lymp homa. In this study, we for the first time demonstrated that miR-449a enhanced apoptosis of T-cell lymphoma cells by decreasing the degree of autophagy. Further, miR-449a downregulated autophagy-associated 4B (ATG4B) expression, which subsequently reduced the autophagy of T-cell lymphoma cells. Mechanistically, miR-449a decreased ATG4B protein level by binding to its mRNA 3’UTR, thus reducing the mRNA stability. In addition, studies with nude mice showed that miR-449a significantly inhibited lymphoma characteristics in vivo. In conclusion, our results demonstrated that the “miR-449a/ATG4B/autophagy” pathway played a vital role in the malignancy of T-cell lymphoma, suggesting a novel therapeutic target.

Inhibition of miR-448-3p Attenuates Cerebral Ischemic Injury by Upregulating Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2)

BACKGROUND

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key regulator responsible for oxidative stress in brain injury. This study aimed to investigate the potential mechanism of miR-448-3p and Nrf2 in cerebral ischemia/reperfusion (I/R) injury.

METHODS

In vitro and in vivo cerebral I/R injury models were constructed, and Nrf2 expression levels were detected by qRT-PCR and Western blot. The potential miRNAs for Nrf2 were predicted by bioinformatic analysis. The binding interaction between miR-448-3p and Nrf2 was determined by luciferase reporter assay. The effects of miR-448-3p on neurological deficit, infarct volume, and brain water content in mice were tested. The effects of miR-448-3p on oxidative stress indicators (SOD activity, MDA content, and ROS production) were detected by commercial assay kits. The levels of HO-1 and cleaved caspase-3 were evaluated by Western blot. Cell viability was evaluated by MTT assay, and cell apoptosis was evaluated by TUNEL staining and flow cytometry.

RESULTS

Nrf2 was significantly downregulated and miR-448-3p was upregulated in cerebral I/R injury both in vivo and in vitro. MiR-448-3p downregulation efficiently attenuated brain injury and reduced oxidative stress and apoptosis. MiR-448-3p was identified to act as ceRNA of Nrf2 and negatively regulated Nrf2 expression, which was consistent with the animal studies. In addition, Nrf2 silencing obviously attenuated the neuroprotective effects of miR-448-3p inhibitor in vitro.

CONCLUSION

MiR-448-3p participated in the regulation of cerebral I/R injury via inhibiting Nrf2.

MicroRNA-mediated autophagy regulation in cancer therapy: The role in chemoresistance/chemosensitivity

Chemoresistance has doubled the effort needed to reach an effective treatment for cancer. Now, scientists should consider molecular pathways and mechanisms involved in chemoresistance to overcome cancer. Autophagy is a "self-digestion" mechanism in which potentially toxic and aged organelles and macromolecules are degraded. Increasing evidence has shown that autophagy possesses dual role in cancer cells (onco-suppressor or oncogene). So, it is vital to identify its role in cancer progression and malignancy. MicroRNAs (miRs) are epigenetic factors capable of modulation of autophagy in cancer cells. In the current review, we emphasize on the relationship between miRs and autophagy in cancer chemotherapy. Besides, we discuss upstream mediators of miR/autophagy axis in cancer chemotherapy including long non-coding RNAs, circular RNAs, Nrf2 c-Myc, and HIF-1α. At the final section, we provide a discussion about how anti-tumor compounds affect miR/autophagy axis in ensuring chemosensitivity. These topics are described in this review to show how autophagy inhibition/induction can lead to chemosensitivity/chemoresistance, and miRs are considered as key players in these discussions.

High Levels of Frataxin Overexpression Lead to Mitochondrial and Cardiac Toxicity in Mouse Models

Friedreich ataxia (FA) is currently an incurable inherited mitochondrial disease caused by reduced levels of frataxin (FXN). Cardiac dysfunction is the main cause of premature death in FA. Adeno-associated virus (AAV)-mediated gene therapy constitutes a promising approach for FA, as demonstrated in cardiac and neurological mouse models. While the minimal therapeutic level of FXN protein to be restored and biodistribution have recently been defined for the heart, it is unclear if FXN overexpression could be harmful. Indeed, depending on the vector delivery route and dose administered, the resulting FXN protein level could reach very high levels in the heart, cerebellum, or off-target organs such as the liver. The present study demonstrates safety of FXN cardiac overexpression up to 9-fold the normal endogenous level but significant toxicity to the mitochondria and heart above 20-fold. We show gradual severity with increasing FXN overexpression, ranging from subclinical cardiotoxicity to left ventricle dysfunction. This appears to be driven by impairment of the mitochondria respiratory chain and ultrastructure, which leads to cardiomyocyte subcellular disorganization, cell death, and fibrosis. Overall, this study underlines the need, during the development of gene therapy approaches, to consider appropriate vector expression level, long-term safety, and biomarkers to monitor such events.

Revisiting cancer hallmarks: insights from the interplay between oxidative stress and non-coding RNAs

Cancer is one of the most common disease worldwide, with complex changes and certain traits which have been described as “The Hallmarks of Cancer.” Despite increasing studies on in-depth investigation of these hallmarks, the molecular mechanisms associated with tumorigenesis have still not yet been fully defined. Recently, accumulating evidence supports the observation that microRNAs and long noncoding RNAs (lncRNAs), two main classes of noncoding RNAs (ncRNAs), regulate most cancer hallmarks through their binding with DNA, RNA or proteins, or encoding small peptides. Reactive oxygen species (ROS), the byproducts generated during metabolic processes, are known to regulate every step of tumorigenesis by acting as second messengers in cancer cells. The disturbance in ROS homeostasis leads to a specific pathological state termed “oxidative stress”, which plays essential roles in regulation of cancer progression. In addition, the interplay between oxidative stress and ncRNAs is found to regulate the expression of multiple genes and the activation of several signaling pathways involved in cancer hallmarks, revealing a potential mechanistic relationship involving ncRNAs, oxidative stress and cancer. In this review, we provide evidence that shows the essential role of ncRNAs and the interplay between oxidative stress and ncRNAs in regulating cancer hallmarks, which may expand our understanding of ncRNAs in the cancer development from the new perspective.

Melatonin Enhances the Therapeutic Effect of Plasma Exosomes Against Cerebral Ischemia-Induced Pyroptosis Through the TLR4/NF-κB Pathway

Introduction

Ischemic stroke-induced inflammation and inflammasome-dependent pyroptotic neural death cause serious neurological injury. Nano-sized plasma exosomes have exhibited therapeutic potential against ischemia and reperfusion injury by ameliorating inflammation. To enhance its therapeutic potential in patients with ischemic injury, we isolated exosomes from melatonin-treated rat plasma and assessed the neurological protective effect in a rat model of focal cerebral ischemia.

Methods

Basal plasma exosomes and melatonin-treated plasma exosomes were isolated and intravenously injected into a rat model of focal cerebral ischemia. Neurological recovery was evaluated by determining the modified neurological severity score (mNSS), infarct volume, and brain water content. Pyroptosis in the ischemic cortex was detected through dUTP nick-end labeling (TUNEL) assay, lactate dehydrogenase (LDH) release, and gasdermin D (GSDMD) cleavage. NLRP3 inflammasome assembly and global inflammatory cytokine secretion were detected by enzyme-linked immunosorbent assay (ELISA) and Western blot assay. In immunized Sprague-Dawley rats, microglia pyroptosis was determined through a positive percentage of IBA1⁺ and caspase-1 (p20)⁺ cells. Finally, the microRNA (miRNA) profiles in melatonin-treated plasma exosomes were analyzed by exosome miRNA microarray analysis.

Results

Melatonin treatment enhanced plasma exosome therapeutic effects against ischemia-induced inflammatory responses and inflammasome-mediated pyroptosis. In addition, we confirmed that ischemic stroke-induced pyroptotic cell death occurred in the microglia and neuron, while the administration of melatonin-treated exosomes further effectively decreased the infarct volume and improved recovery of function via regulation of the TLR4/NF-κB signaling pathway. Finally, the altered miRNA profiles in the melatonin-treated plasma exosomes demonstrated the regulatory mechanisms involved in neurological recovery after ischemic injury.

Conclusion

This study suggests that nano-sized plasma exosomes with melatonin pretreatment might be a more effective strategy for patients with ischemic brain injury. Further exploration of key molecules in the plasma exosome may provide increased therapeutic value for cerebral ischemic injury.

Crosstalk between noncoding RNAs and ferroptosis: new dawn for overcoming cancer progression

Cancer progression including proliferation, metastasis, and chemoresistance has become a serious hindrance to cancer therapy. This phenomenon mainly derives from the innate insensitive or acquired resistance of cancer cells to apoptosis. Ferroptosis is a newly discovered mechanism of programmed cell death characterized by peroxidation of the lipid membrane induced by reactive oxygen species. Ferroptosis has been confirmed to eliminate cancer cells in an apoptosis-independent manner, however, the specific regulatory mechanism of ferroptosis is still unknown. The use of ferroptosis for overcoming cancer progression is limited. Noncoding RNAs have been found to play an important roles in cancer. They regulate gene expression to affect biological processes of cancer cells such as proliferation, cell cycle, and cell death. Thus far, the functions of ncRNAs in ferroptosis of cancer cells have been examined, and the specific mechanisms by which noncoding RNAs regulate ferroptosis have been partially discovered. However, there is no summary of ferroptosis associated noncoding RNAs and their functions in different cancer types. In this review, we discuss the roles of ferroptosis-associated noncoding RNAs in detail. Moreover, future work regarding the interaction between noncoding RNAs and ferroptosis is proposed, the possible obstacles are predicted and associated solutions are put forward. This review will deepen our understanding of the relationship between noncoding RNAs and ferroptosis, and provide new insights in targeting noncoding RNAs in ferroptosis associated therapeutic strategies.

LncRNA NEAT1/miR-129/Bcl-2 signaling axis contributes to HDAC inhibitor tolerance in nasopharyngeal cancer

Histone deacetylase inhibitors (HDACis) - based therapeutic drug tolerance is one of the principal factors of poor prognosis of patients with nasopharyngeal cancer (NPC). Mechanisms of tolerance to HDACis are not well understood. Nowadays, dysregulation of long non-coding RNAs (LncRNAs) and microRNAs (miRNAs) has been reported to provide beneficial or inhibitory effects in drug-tolerance in various cancers. Herein, we established the HDAC inhibitor (SAHA)-tolerant NPC cell sublines, which had decreased apoptosis in response to SAHA treatment. We observed that the expression of miR-129 was significantly reduced in SAHA-tolerant NPC cells. Manipulating the expression of miR-129 overcame SAHA tolerance, and enhanced the SAHA-induced apoptosis. In terms of miR-129 downregulation, we identified that NEAT1 suppresses miR-129 expression. NEAT1 was found to be upregulated in SAHA tolerance cells. The depletion of NEAT1 phenocopied the effect of miR-129 overexpression, which also enhanced SAHA-induced apoptosis. Bcl-2 was the downstream target of miR-129 and contributed to SAHA tolerance in NPC. Our in vivo xenograft experiment confirmed that the administration of miR-129 or inhibition of Bcl-2 overcame the SAHA tolerance in NPC. In conclusion, NEAT1 increases in NPC tissues and manages to facilitate SAHA tolerance by modulating the miR-129/Bcl-2 axis, providing novel therapeutic targets for NPC treatment.

MicroRNAs Modulate Drug Resistance-Related Mechanisms in Hepatocellular Carcinoma

Primary liver cancer [hepatocellular carcinoma (HCC)] is one of the most common malignant tumors worldwide, causing serious health threats because of its high morbidity and mortality, rapid growth, and strong invasiveness. Patients with HCC frequently develop resistance to the current chemotherapeutic drugs, and this is largely attributed to the high-level heterogeneity of the tumor tissue. MicroRNAs (miRNAs) are a group of master regulators for multiple physiological and pathological processes and play important roles in the tumorigenesis. More recent studies have indicated that miRNAs also play a non-negligible role in the development of drug resistance in liver cancer. In this review, we summarize the data from the latest studies on the mechanisms of drug resistance in liver cancer, including autophagy, membrane transporters, epithelial-mesenchymal transitions (EMTs), tumor microenvironment, and genes and proteins that are associated with apoptosis. The data herein will provide valuable information for the development of novel approaches to tackle drug resistance in the management of liver cancer.

Histone Deacetylase Inhibitor Sensitizes ERCC1-High Non-small-Cell Lung Cancer Cells to Cisplatin via Regulating miR-149

Resistance to platinum-based chemotherapy becomes a major obstacle in non-small-cell lung cancer (NSCLC) treatment. Overexpression of the excision repair cross-complementing 1 (ERCC1) gene is reported to negatively influence the effectiveness of cisplatin-based therapy for NSCLC cells. In this study, we confirm that high ERCC1 expression correlates with cisplatin resistance in NSCLC cells. Importantly, histone deacetylase inhibitors (HDACis) re-sensitize ERCC1-high NSCLC cells to cisplatin both in vitro and in vivo. Mechanistically, the HDACi induces the expression of miR-149 by acetylation and activation of E2F1, which directly targets ERCC1 and inhibits ERCC1 expression. Inhibition of miR-149 reverses the promotion effect of HDACis on cisplatin-induced DNA damage and cell apoptosis in ERCC1-high NSCLC cells. In conclusion, this study reveals a novel mechanism by which HDACis re-sensitizes ERCC1-high NSCLC cells to cisplatin via regulation of the E2F1/miR-149/ERCC1 axis, and we propose that combination of HDACis and cisplatin might hold promise to be a more effective therapeutic paradigm for ERCC1-high NSCLCs.

MiR-449a attenuates autophagy of T-cell lymphoma cells by downregulating ATG4B expression

Increasing evidence suggests the role of miR-449a in the regulation of tumorigenesis and autophagy. Autophagy plays an important role in the malignancy of T-cell lymphoma. However, it is still unknown whether miR-449a is associated with autophagy to regulate the malignancy of T-cell lymp homa. In this study, we for the first time demonstrated that miR-449a enhanced apoptosis of T-cell lymphoma cells by decreasing the degree of autophagy. Further, miR-449a downregulated autophagy-associated 4B (ATG4B) expression, which subsequently reduced the autophagy of T-cell lymphoma cells. Mechanistically, miR-449a decreased ATG4B protein level by binding to its mRNA 3'UTR, thus reducing the mRNA stability. In addition, studies with nude mice showed that miR-449a significantly inhibited lymphoma characteristics in vivo. In conclusion, our results demonstrated that the "miR-449a/ATG4B/autophagy" pathway played a vital role in the malignancy of T-cell lymphoma, suggesting a novel therapeutic target. [BMB Reports 2020; 53(5): 254-259].

MicroRNA-mediated regulation of Nrf2 signaling pathway: Implications in disease therapy and protection against oxidative stress

MicroRNAs (miRs) are small non-coding pieces of RNA that are involved in a variety of physiologic processes such as apoptosis, cell proliferation, cell differentiation, cell cycle and cell survival. These multifunctional nucleotides are also capable of preventing oxidative damages by modulating antioxidant defense systems in a variety of milieu, such as in diabetes. Although the exact molecular mechanisms by which miRs modulate the antioxidant defense elements are unclear, some evidence suggests that they may exert these effects via nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. This intracellular mechanism is crucial in the maintenance of the physiologic redox balance by regulating the expression and activity of various cellular antioxidative defense elements and thereby plays a pivotal role in the development of oxidative stress. Any impairment in the Nrf2 signaling pathway may result in oxidative damage-dependent complications such as various diabetic complications, neurological disorders and cancer. In the current review, we discuss the modulatory effects of miRs on the Nrf2 signaling pathway, which can potentially be novel therapeutic targets.

Molecular Determinants of Cancer Therapy Resistance to HDAC Inhibitor-Induced Autophagy

Histone deacetylation inhibitors (HDACi) offer high potential for future cancer therapy as they can re-establish the expression of epigenetically silenced cell death programs. HDACi-induced autophagy offers the possibility to counteract the frequently present apoptosis-resistance as well as stress conditions of cancer cells. Opposed to the function of apoptosis and necrosis however, autophagy activated in cancer cells can engage in a tumor-suppressive or tumor-promoting manner depending on mostly unclarified factors. As a physiological adaption to apoptosis resistance in early phases of tumorigenesis, autophagy seems to resume a tumorsuppressive role that confines tumor necrosis and inflammation or even induces cell death in malignant cells. During later stages of tumor development, chemotherapeutic drug-induced autophagy seems to be reprogrammed by the cancer cell to prevent its elimination and support tumor progression. Consistently, HDACi-mediated activation of autophagy seems to exert a protective function that prevents the induction of apoptotic or necrotic cell death in cancer cells. Thus, resistance to HDACi-induced cell death is often encountered in various types of cancer as well. The current review highlights the different mechanisms of HDACi-elicited autophagy and corresponding possible molecular determinants of therapeutic resistance in cancer.

MicroRNA-Based Combinatorial Cancer Therapy: Effects of MicroRNAs on the Efficacy of Anti-Cancer Therapies

The susceptibility of cancer cells to different types of treatments can be restricted by intrinsic and acquired therapeutic resistance, leading to the failure of cancer regression and remission. To overcome this problem, a combination therapy has been proposed as a fundamental strategy to improve therapeutic responses; however, resistance is still unavoidable. MicroRNA (miRNAs) are associated with cancer therapeutic resistance. The modulation of dysregulated miRNA levels through miRNA-based therapy comprising a replacement or inhibition approach has been proposed to sensitize cancer cells to other anti-cancer therapies. The combination of miRNA-based therapy with other anti-cancer therapies (miRNA-based combinatorial cancer therapy) is attractive, due to the ability of miRNAs to target multiple genes associated with the signaling pathways controlling therapeutic resistance. In this article, we present an overview of recent findings on the role of therapeutic resistance-related miRNAs in different types of cancer. We review the feasibility of utilizing dysregulated miRNAs in cancer cells and extracellular vesicles as potential candidates for miRNA-based combinatorial cancer therapy. We also discuss innate properties of miRNAs that need to be considered for more effective combinatorial cancer therapy.

Bergenin impedes the generation of extracellular matrix in glomerular mesangial cells and ameliorates diabetic nephropathy in mice by inhibiting oxidative stress via the mTOR/β-TrcP/Nrf2 pathway

Bergenin, a plant polyphenol, has been reported to lower the blood glucose level and ameliorate kidney function in streptozotocin (STZ)-induced diabetic rats. Herein, its protective effect on diabetic nephropathy (DN) was explored in view of extracellular matrix (ECM) generation in glomerular mesangial cells. Glomerular mesangial cells were treated with high glucose, and Q-PCR as well as western blot were used to determine the expression of ECM. To establish the participation and role of mammalian target of rapamycin (mTOR) and nuclear factor erythroid-derived 2-related factor 2 (Nrf2) in ECM generation, a combination of l-leucine (activator of mTOR) and Nrf2 shRNA transfection were performed, respectively. Moreover, a DN model was established in mice using high-glucose/high-fat diet and STZ. Bergenin impeded the generation of TGF-β1 and ECM, decreased the levels of intracellular superoxide anion and hydrogen peroxide, and increased the activity of antioxidant enzymes in the glomerular mesangial cells (HBZY-1 and HRMC cells) treated with high glucose. The inhibition of ECM generation by bergenin was dependent on the down-regulation of oxidative stress as confirmed via a superoxide overexpression system. The activation of Nrf2 was required for bergenin to inhibit the oxidative stress and ECM generation. Moreover, bergenin was found to inhibit the phosphorylation of mTOR, which is located at the upstream of Nrf2. Bergenin did not interfere with the expression of Nrf2 mRNA and Keap1 (the classic degradation control factor of Nrf2), but markedly inhibited the protein expression of the β-TrcP, an effect which could be abolished by l-leucine. In DN model mice, l-leucine diminished the ability of bergenin to reduce the levels of superoxide anion, hydrogen peroxide and ECM, which contributed to the eradication of the ameliorative effect of bergenin on nephropathy. Bergenin can inhibit glucose-induced ECM production in glomerular mesangial cells through the down-regulation of oxidative stress via the mTOR/β-TrcP/Nrf2 pathway, and it might be a candidate drug for the prevention and treatment of DN.

CircCDR1as upregulates autophagy under hypoxia to promote tumor cell survival via AKT/ERK½/mTOR signaling pathways in oral squamous cell carcinomas

Autophagy, as an important non-selective degradation mechanism, could promote tumor initiation and progression by maintaining cellular homeostasis and the cell metabolism as well as cell viability. CircCDR1as has been shown to function as an oncogene in cancer progression, however, it remains largely unknown as to how autophagy is regulated by circCDR1as in oral squamous cell carcinoma (OSCC). In this study, we validated the functional roles of circCDR1as in regulation of autophagy in OSCC cells and further investigated how circCDR1as contributed to cell survival via up-regulating autophagy under a hypoxic microenvironment by using combination of human tissue model, in vitro cell experiments and in vivo mice model. We found that hypoxia promoted the expression level of circCDR1as in OSCC cells and elevated autophagy. In addition, circCDR1as further increased hypoxia-mediated autophagy by targeting multiple key regulators of autophagy. We revealed that circCDR1as enhanced autophagy in OSCC cells via inhibition of rapamycin (mTOR) activity and upregulation of AKT and ERK_½ pathways. Overexpression of circCDR1as enhanced OSCC cells viability, endoplasmic reticulum (ER) stress, and inhibited cell apoptosis under a hypoxic microenvironment. Moreover, circCDR1as promoted autophagy in OSCC cells by sponging miR-671-5p. Collectively, these results revealed that high expression of circCDR1as enhanced the viability of OSCC cells under a hypoxic microenvironment by promoting autophagy, suggesting a novel treatment strategy involving circCDR1as and the inhibition of autophagy in OSCC cells.

Dual roles and therapeutic potential of Keap1-Nrf2 pathway in pancreatic cancer: a systematic review

Pancreatic cancer (PC) is one of the most fatal diseases with a very high rate of metastasis and low rate of survival. Despite the advances in understanding this devastating disease, PC still accounts for 3% of all cancers and causes almost 7% of death of cancer patients. Recent studies have demonstrated that the transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2) and its key negative regulator Kelch-like ECH-associated protein 1 (Keap1) are dysregulated in PC and the Keap1-Nrf2 pathway is an emerging target for PC prevention and therapy. Indeed, Nrf2 plays an either tumor-suppressive or promoting function in PC, which depends on the developmental stages of the disease and the cellular context. Several natural-product Nrf2 activators have been developed to prevent pancreatic carcinogenesis, while the Nrf2 inhibitors have been examined for their efficacy in inhibiting PC growth and metastasis and reversing chemoresistance. However, further preclinical and clinical studies for determining the effectiveness and safety of targeting the Keap1-Nrf2 pathway for PC prevention and therapy are warranted. In this review, we comprehensively discuss the dual roles of the Keap1-Nrf2 signaling pathway in PC as well as the current targeting strategies and known activators and inhibitors of Nrf2. We also propose new strategies that may be used to address the current issues and develop more specific and more effective Nrf2 activator/inhibitors for PC prevention and therapy.

p53 at the Crossroads between Different Types of HDAC Inhibitor-Mediated Cancer Cell Death

Cancer is a complex genetic and epigenetic-based disease that has developed an armada of mechanisms to escape cell death. The deregulation of apoptosis and autophagy, which are basic processes essential for normal cellular activity, are commonly encountered during the development of human tumors. In order to assist the cancer cell in defeating the imbalance between cell growth and cell death, histone deacetylase inhibitors (HDACi) have been employed to reverse epigenetically deregulated gene expression caused by aberrant post-translational protein modifications. These interfere with histone acetyltransferase- and deacetylase-mediated acetylation of both histone and non-histone proteins, and thereby exert a wide array of HDACi-stimulated cytotoxic effects. Key determinants of HDACi lethality that interfere with cellular growth in a multitude of tumor cells are apoptosis and autophagy, which are either mutually exclusive or activated in combination. Here, we compile known molecular signals and pathways involved in the HDACi-triggered induction of apoptosis and autophagy. Currently, the factors that determine the mode of HDACi-elicited cell death are mostly unclear. Correspondingly, we also summarized as yet established intertwined mechanisms, in particular with respect to the oncogenic tumor suppressor protein p53, that drive the interplay between apoptosis and autophagy in response to HDACi. In this context, we also note the significance to determine the presence of functional p53 protein levels in the cancer cell. The confirmation of the context-dependent function of autophagy will pave the way to improve the benefit from HDACi-mediated cancer treatment.