MicroRNA-21 modulates the levels of reactive oxygen species by targeting SOD3 and TNFα

microRNA-378a Regulates the Reactive Oxygen Species (ROS)/Phosphatidylinositol 3-Kinases (PI3K)/AKT Signaling Pathway in Human Lens Epithelial Cells and Cataract

BACKGROUND Cataract is associated with increased apoptosis of the epithelial cells of the ocular lens. Previous studies have shown that microRNA-378a (miR-378a) has a role in the development of cataract, but the molecular mechanisms remain unclear. This study aimed to investigate the effects of miR-378a in human lens epithelial cells (HLECs) in vitro and normal lens tissues and cataract tissues. MATERIAL AND METHODS HLECs were grown in culture. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blot were used to examine gene expression levels. The MTT and TUNEL assay measured cell growth and apoptosis. Changes in the fluorescence ratio of ethidium to dihydroethidium (E: DHE) and in 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate (C-H₂DCFDA) were used to detect superoxide (O₂⁻) and hydrogen peroxide (H₂O₂). The expression levels of miR-378a and the superoxide dismutase 1 gene (SOD1) were measured in normal human lens tissues and cataract tissues. RESULTS Upregulation of miR-378a reduced the expression of SOD1. Levels of O₂⁻ were upregulated and H₂O₂ was slightly down-regulated by miR-378a. The use of a miR-378a mimic suppressed cell growth and enhanced apoptosis of HLECs, which were reversed by the use of a miR-378a inhibitor. SOD1 overexpression rescued the miR-378a-induced phenotypes of HLEC cells. Treatment with the PI3K inhibitor, LY294002, reversed miR-378a and ROS-regulated proliferation and apoptosis of HLEC cells. Also, miR-378a was upregulated, and SOD1 was down-regulated in human cataract tissues. CONCLUSIONS In HLECs, expression of miR-378a regulated ROS and PI3K/AKT signaling, and miR-378a was upregulated, and SOD1 was down-regulated in human cataract tissue.

Co-Detection of miR-21 and TNF-α mRNA in Budding Cancer Cells in Colorectal Cancer

MicroRNA-21 (miR-21) is upregulated in many cancers including colon cancers and is a prognostic indicator of recurrence and poor prognosis. In colon cancers, miR-21 is highly expressed in stromal fibroblastic cells and more weakly in a subset of cancer cells, particularly budding cancer cells. Exploration of the expression of inflammatory markers in colon cancers revealed tumor necrosis factor alpha (TNF-α) mRNA expression at the invasive front of colon cancers. Surprisingly, a majority of the TNF-α mRNA expressing cells were found to be cancer cells and not inflammatory cells. Because miR-21 is positively involved in cell survival and TNF-α promotes necrosis, we found it interesting to analyze the presence of miR-21 in areas of TNF-α mRNA expression at the invasive front of colon cancers. For this purpose, we developed an automated procedure for the co-staining of miR-21, TNF-α mRNA and the cancer cell marker cytokeratin based on analysis of frozen colon cancer tissue samples (n = 4) with evident cancer cell budding. In all four cases, TNF-α mRNA was seen in a small subset of cancer cells at the invasive front. Evaluation of miR-21 and TNF-α mRNA expression was performed on digital slides obtained by confocal slide scanning microscopy. Both co-expression and lack of co-expression with miR-21 in the budding cancer cells was noted, suggesting non-correlated expression. miR-21 was more often seen in cancer cells than TNF-α mRNA. In conclusion, we report that miR-21 is not linked to expression of the pro-inflammatory cytokine TNF-α mRNA, but that miR-21 and TNF-α both take part in the cancer expansion at the invasive front of colon cancers. We hypothesize that miR-21 may protect both fibroblasts and cancer cells from cell death directed by TNF-α paracrine and autocrine activity.

Effects of quercetin on microRNAs: A mechanistic review

MicroRNA (miRNA)-dependent pathways are one of the newest gene regulation mechanisms in various diseases, particularly in cancers. miRNAs are endogenous noncoding RNAs with about 18 to 25 nucleotide length, which can regulate the expression of at least 60% of human total genome posttranscriptionally. Quercetin is the most abundant flavonoid in a variety of fruits, flowers, and medical herbs, known as a strong free radical scavenger that could show antioxidant, anti-inflammatory, and antitumor activities. Recent studies also reported its strong impact on various miRNA expressions in different abnormalities. In this review, we aimed to summarize the studies focused on the effects of quercetin on different miRNA expressions to more clear the main possible mechanisms of quercetin influences and introduce it as a beneficial agent for regulation of miRNAs in various biological directions.

Reduced camptothecin sensitivity of estrogen receptor-positive human breast cancer cells following exposure to di(2-ethylhexyl)phthalate (DEHP) is associated with DNA methylation changes

Di(2-ethylhexyl)phthalate (DEHP) has been considered as an estrogen receptor alpha (ERα) agonist due to its ability to interact with ERα and promote the cell proliferation of ERα-positive breast cancer cells. The impact of DEHP on the chemical therapy in breast cancer is little known. Two breast cancer cell lines, MCF-7 (ERα-dependent) and MDA-MB-231 (ERα-independent) were examined. We found that DEHP impaired the effectiveness of camptothecin (CPT) and alleviated the CPT-induced formation of reactive oxygen species in ERα-positive MCF-7 cells, but not in ERα-negative MDA-MB-231 cells. DEHP also significantly protected MCF-7 cells against the genotoxicity of CPT. Genome-wide DNA methylation profiling revealed that after 48 hours of exposure to 100 μM DEHP, MCF-7 cells exhibited a significant change in their DNA methylation pattern, including hypermethylation of 700 genes and hypomethylation of 221 genes. The impaired therapeutic response to CPT in DEHP-exposed MCF-7 cells is probably mediated by epigenetic changes, especially through Wnt/β-catenin signaling. A zebrafish xenograft model confirmed the disruptive effect of DEHP on CPT-induced anti-growth of MCF-7 cells. In summary, DEHP exposure induces acquired CPT-resistance in breast cancer cells and epigenetic changes associated with Wnt/β-catenin signaling activation are probably depending on an ER-positive status.

Dysregulated Expression of microRNA-21 and Disease-Related Genes in Human Patients and in a Mouse Model of Alport Syndrome

Alport syndrome is a genetic disease caused by mutations in type IV collagen and is characterized by progressive kidney disease. The Col4α3^-/- mouse model recapitulates the main features of human Alport syndrome. Previously, it was reported that kidney microRNA-21 (miR-21) expression is significantly increased in Col4α3^-/- mice, and administration of anti-miR-21 oligonucleotides (anti-miR-21) attenuates kidney disease progression in Col4α3^-/- mice, indicating that miR-21 is a viable therapeutic target for Alport syndrome. However, the expression pattern of miR-21 in the kidneys of patients with human Alport syndrome has not been evaluated. Paraffin-embedded kidney specimens were obtained from 27 patients with Alport syndrome and from 10 normal controls. They were evaluated for miR-21 expression and for in situ hybridization and mRNA expression by quantitative polymerase chain reaction. In addition, anti-miR-21 was administrated to Col4α3^-/- mice at different stages of disease, and changes in proteinuria, kidney function, and survival were monitored. Transcriptomic analysis of mouse kidney was conducted using RNA sequencing. miR-21 expression was significantly elevated in kidney specimens from patients with Alport syndrome compared to normal controls. Elevated renal miR-21 expression positively correlated with 24 h urine protein, serum blood urea nitrogen, serum creatinine, and severity of kidney pathology. On histological evaluation, high levels of miR-21 were localized to damaged tubular epithelial cells and glomeruli. Kidney specimens from both humans and mice with Alport syndrome exhibited abnormal expression of genes involved in kidney injury, fibrosis, inflammation, mitochondrial function, and lipid metabolism. Administration of anti-miR-21 to Alport mice resulted in slowing of kidney function decline, partial reversal of abnormal gene expression associated with disease pathology, and improved survival. Increased levels of miR-21 in human Alport kidney samples showed a correlation with kidney disease severity measured by proteinuria, biomarkers of kidney function, and kidney histopathology scores. These human data, combined with the finding that a reduction of miR-21 in Col4α3^-/- mice improves kidney phenotype and survival, support miR-21 as a viable therapeutic target for the treatment of Alport syndrome.

Ionizing radiation-induced growth in soft agar is associated with miR-21 upregulation in wild-type and DNA double strand break repair deficient cells

DNA double strand breaks (DSBs) are a severe threat to genome integrity and a potential cause of tumorigenesis, which is a multi-stage process and involves many factors including the mutation of oncogenes and tumor suppressors, some of which are transcribed microRNAs (miRNAs). Among more than 2000 known miRNAs, miR-21 is a unique onco-miRNA that is highly expressed in almost all types of human tumors and is associated with tumorigenesis through its multiple targets. However, it remains unclear whether there is any functional link between DSBs and miR-21 expression and, if so, does the link contribute to DSB-induced genomic instability/tumorigenesis. To address this question, we used DNA-PKcs-/- (deficient in non-homologous end-joining (NHEJ)) and Rad54-/- (deficient in homologous recombination repair (HRR)) mouse embryonic fibroblasts (MEFs) since NHEJ and HRR are the major pathways for DSB repair in mammalian cells. Our results indicate that levels of miR-21 are elevated in these DSB repair (DSBR) deficient cells, and ionizing radiation (IR) further increases these levels in both wild-type (WT) and DSBR-deficient cells. Interestingly, IR stimulated growth in soft agar and this effect was greatly reduced by blocking miR-21 expression in both WT and DSBR-deficient cells. Taken together, our results suggest that either IR or DSBR-deficient can lead to an upregulation of miR-21 levels and that miR-21 is associated with IR-induced cell growth in soft agar. These results may help our understanding of DSB-induced tumorigenesis and provide information that could facilitate the development of new strategies to prevent DSB-induced carcinogenesis.

Carcinogenesis and Reactive Oxygen Species Signaling: Interaction of the NADPH Oxidase NOX1-5 and Superoxide Dismutase 1-3 Signal Transduction Pathways

SIGNIFICANCE

Reduction/oxidation (redox) balance could be defined as an even distribution of reduction and oxidation complementary processes and their reaction end products. There is a consensus that aberrant levels of reactive oxygen species (ROS), commonly observed in cancer, stimulate primary cell immortalization and progression of carcinogenesis. However, the mechanism how different ROS regulate redox balance is not completely understood. Recent Advances: In the current review, we have summarized the main signaling cascades inducing NADPH oxidase NOX1-5 and superoxide dismutase (SOD) 1-3 expression and their connection to cell proliferation, immortalization, transformation, and CD34+ cell differentiation in thyroid, colon, lung, breast, and hematological cancers.

CRITICAL ISSUES

Interestingly, many of the signaling pathways activating redox enzymes or mediating the effect of ROS are common, such as pathways initiated from G protein-coupled receptors and tyrosine kinase receptors involving protein kinase A, phospholipase C, calcium, and small GTPase signaling molecules.

FUTURE DIRECTIONS

The clarification of interaction of signal transduction pathways could explain how cells regulate redox balance and may even provide means to inhibit the accumulation of harmful levels of ROS in human pathologies.

Suppression of miR-21 and miR-155 of macrophage by cinnamaldehyde ameliorates ulcerative colitis

Ulcerative colitis (UC) is a major form of inflammatory bowel disease which involved mucosal immune dysfunction. Cinnamaldehyde (CA) is major active compound from cinnamon, a useful traditional medicine in Asia which shows superior antibacterial and anti-inflammatory activity. In this study, we investigated the effects of CA on UC both in vivo and in vitro. We showed that CA attenuated the symptoms of DSS-induced colitis, including loss of body weights, disease activity index (DAI), shortening of the colon lengths and infiltration of inflammatory cells. Moreover, CA decreased the pro-inflammatory cytokines and NLRP3 inflammasome, miR-21 and miR-155 in colon tissues, in addition, the percentage of macrophages was reduced based on the surface marker F4/80 and IL-10 secretion in CA-treated group, suggesting that the CA ameliorate the UC via activation of macrophage. Herein, the effects of CA on macrophage cells were examined in vitro. We found that CA reduced the level of proinflammatory cytokines, such as TNF-α, IL-1β, IL-6, in the activation of RAW264.7, human macrophage-like cells U937, and primary peritoneal macrophages. Furthermore, the suppression of NLRP3 inflammasome, miR-21 and miR-155 was also found in CA-treated LPS-stimulated RAW264.7 cells. CA also reduced the production of reactive oxygen species, the phosphorylation of AKT, mTOR and COX2 protein level in the RAW264.7. Meanwhile, data revealed that transferred miR-21 or miR-155 inhibitor suppressed levels of IL-1β and IL-6, whereas miR-21 or miR-155 mimics increased expressions of these, and CA suppressed these expressions. Our results indicate that CA could ameliorate DSS-induced colitis through inhibition of NLRP3 inflammasome activation and miR-21 and miR-155 levels in colons and macrophage, suggesting that CA might be a potentially effective drug for UC.

Relationship of peripheral blood mononuclear cells miRNA expression and parasitic load in canine visceral leishmaniasis

Visceral leishmaniasis (VL) in humans is a chronic and often fatal disease if left untreated. Dogs appear to be the main reservoir host for L. infantum infection, however, in many regions other canids such as jackals, foxes, wolves and other mammals, such as hares or black rats, have been implicated as wild reservoirs. Most dogs cannot form an effective immune response against this infection, and this could be modulated by small non-coding RNAs, called microRNAs, responsible for post-transcriptional control of gene expression. Here, we evaluated the expression of miRNAs in peripheral blood mononuclear cells (PBMC) of symptomatic dogs naturally infected with Leishmania (L.) infantum (n = 10) and compared to those of healthy dogs (n = 5). Microarray analysis revealed that miR-21, miR-424, miR-194 and miR-451 had a 3-fold increase in expression, miR-192, miR-503, and miR-371 had a 2-fold increase in expression, whereas a 2-fold reduction in expression was observed for miR-150 and miR-574. Real-time PCR validated the differential expression of miR-21, miR-150, miR-451, miR-192, miR-194, and miR-371. Parasite load of PBMC was measured by real-time PCR and correlated to the differentially expressed miRNAs, showing a strong positive correlation with expression of miR-194, a regular positive correlation with miR-371 expression, and a moderate negative correlation with miR-150 expression in PBMC. These findings suggest that Leishmania infection interferes with miRNAs expression in PBMC, and their correlation with parasite load may help in the identification of therapeutic targets in Canine Visceral Leishmaniasis (CVL).

MicroRNAs Regulating Reactive Oxygen Species in Cardiovascular Diseases

SIGNIFICANCE

Oxidative stress caused by overproduction of reactive oxygen species (ROS) in cells is one of the most important contributors to the pathogenesis of cardiovascular and metabolic diseases such as hypertension and atherosclerosis. Excessive accumulation of ROS impairs, while limiting oxidative stress protects cardiovascular and metabolic function through various cellular mechanisms. Recent Advances: MicroRNAs (miRNAs) are novel regulators of oxidative stress in cardiovascular cells that modulate the expression of redox-related genes. This article summarizes recent advances in our understanding of how miRNAs target major ROS generators, antioxidant signaling pathways, and effectors in cells of the cardiovascular system.

CRITICAL ISSUES

The role of miRNAs in regulating ROS in cardiovascular cells is complicated because miRNAs can target multiple redox-related genes, act on redox regulatory pathways indirectly, and display context-dependent pro- or antioxidant effects. The complex regulatory network of ROS and the plethora of targets make it difficult to pin point the role of miRNAs and develop them as therapeutics. Therefore, these properties should be considered when designing strategies for therapeutic or diagnostic development.

FUTURE DIRECTIONS

Future studies can gain a better understanding of redox-related miRNAs by investigating their own regulatory mechanisms and the dual role of ROS in the cardiovascular systems. The combination of improved study design and technical advancements will reveal newer pathophysiological importance of redox-related miRNAs.

Changes in gene expression as one of the key mechanisms involved in radiation-induced bystander effect

The radiation-induced bystander effect (RIBE) refers to the manifestation of responses by non-targeted/non-hit cells or tissues situated in proximity to cells and tissues directly exposed to ionizing radiation (IR). The RIBE is elicited by agents and factors released by IR-hit cells. The growing body of data suggests that the underlying mechanisms of the RIBE are multifaceted depending both on the biological (characteristics of directly IR-exposed cells, bystander cells, intercellular milieu) and the physical (dose, rate and type of IR, time after exposure) factors/parameters. Although the exact identity of bystander signal(s) is yet to be identified, the published data indicate changes in gene expression for multiple types of RNA (mRNA, microRNA, mitochondrial RNA, long non-coding RNA, small nucleolar RNA) as being one of the major responses of cells and tissues in the context of the RIBE. Gene expression profiles demonstrate a high degree of variability between distinct bystander cell and tissue types. These alterations could independently, or in a signaling cascade, result in the manifestation of readily observable endpoints, including changes in viability and genomic instability. Here, the relevant publications on the gene candidates and signaling pathways involved in the RIBE are reviewed, and a framework for future studies, both in vitro and in vivo, on the genetic aspect of the RIBE is provided.

Stress-associated changes in salivary microRNAs can be detected in response to the Trier Social Stress Test: An exploratory study

Stress is an important co-factor for the genesis and maintenance of many diseases and is known to have an effect on gene expression via epigenetic regulation. MicroRNAs (miRNAs) appear to function as one of the key factors of this regulation. This is the first study to investigate the response of 11 stress-associated miRNAs in human saliva - as a non-invasive source - in an experimental condition of acute psychological stress, and also their correlation with established psychological (subjective stress perception), physiological (heart rate and heart rate variability) and biochemical stress parameters (salivary cortisol and alpha-amylase). 24 healthy participants between 20 and 35 years of age were investigated, using the Trier Social Stress Test (TSST) to induce acute psychological stress. Stress-associated changes were significant for miR-20b, -21 and 26b, and changes in miR-16 and -134 were close to significance, recommending further research on these miRNAs in the context of stress reactions. Significant correlations with alpha-amylase suggest their integration in sympathetic stress regulation processes. Additionally, our results demonstrate the TSST as a reliable tool for studying salivary miRNAs as non-invasive indicators of epigenetic processes in acute psychological stress reactions.

TNF-driven adaptive response mediates resistance to EGFR inhibition in lung cancer

Although aberrant EGFR signaling is widespread in cancer, EGFR inhibition is effective only in a subset of non-small cell lung cancer (NSCLC) with EGFR activating mutations. A majority of NSCLCs express EGFR wild type (EGFRwt) and do not respond to EGFR inhibition. TNF is a major mediator of inflammation-induced cancer. We find that a rapid increase in TNF level is a universal adaptive response to EGFR inhibition in NSCLC, regardless of EGFR status. EGFR signaling actively suppresses TNF mRNA levels by inducing expression of miR-21, resulting in decreased TNF mRNA stability. Conversely, EGFR inhibition results in loss of miR-21 and increased TNF mRNA stability. In addition, TNF-induced NF-κB activation leads to increased TNF transcription in a feed-forward loop. Inhibition of TNF signaling renders EGFRwt-expressing NSCLC cell lines and an EGFRwt patient-derived xenograft (PDX) model highly sensitive to EGFR inhibition. In EGFR-mutant oncogene-addicted cells, blocking TNF enhances the effectiveness of EGFR inhibition. EGFR plus TNF inhibition is also effective in NSCLC with acquired resistance to EGFR inhibition. We suggest concomitant EGFR and TNF inhibition as a potentially new treatment approach that could be beneficial for a majority of lung cancer patients.

Neuroprotection afforded by circadian regulation of intracellular glutathione levels: A key role for miRNAs

Circadian rhythms are approximately 24-h oscillations of physiological and behavioral processes that allow us to adapt to daily environmental cycles. Like many other biological functions, cellular redox status and antioxidative defense systems display circadian rhythmicity. In the central nervous system (CNS), glutathione (GSH) is a critical antioxidant because the CNS is extremely vulnerable to oxidative stress; oxidative stress, in turn, causes several fatal diseases, including neurodegenerative diseases. It has long been known that GSH level shows circadian rhythm, although the mechanism underlying GSH rhythm production has not been well-studied. Several lines of recent evidence indicate that the expression of antioxidant genes involved in GSH homeostasis as well as circadian clock genes are regulated by post-transcriptional regulator microRNA (miRNA), indicating that miRNA plays a key role in generating GSH rhythm. Interestingly, several reports have shown that alterations of miRNA expression as well as circadian rhythm have been known to link with various diseases related to oxidative stress. A growing body of evidence implicates a strong correlation between antioxidative defense, circadian rhythm and miRNA function, therefore, their dysfunctions could cause numerous diseases. It is hoped that continued elucidation of the antioxidative defense systems controlled by novel miRNA regulation under circadian control will advance the development of therapeutics for the diseases caused by oxidative stress.

MicroRNAs as regulators of mitochondrial dysfunction and obesity

Obesity, which has become a major global epidemic, is associated with numerous comorbidities and nearly every chronic condition. Mitochondria play a central role in this disorder, as they control cell metabolism, regulating important processes, such as ATP production, lipid β-oxidation, oxidative stress, and inflammation. MicroRNAs (miRs) have been shown to regulate many biological processes associated with obesity, comprising adipocyte differentiation, insulin action, and fat metabolism. In addition, recent studies have confirmed that miRs are important regulators of mitochondrial function by either directly modulating mitochondrial proteins or targeting mitochondrial regulators, thereby modulating metabolic process in the context of obesity. In this review, we describe the different roles of mitochondria in obesity, specifically in adipose tissue, and those miRs that are involved in mitochondrial dysfunction in this disease.

Molecular mechanism of bystander effects and related abscopal/cohort effects in cancer therapy

Cancer cells subjected to ionizing radiation may release signals which can influence nearby non-irradiated cells, termed bystander effects. The transmission of bystander effects among cancer cells involves the activation of inflammatory cytokines, death ligands, and reactive oxygen/nitrogen species. In addition to bystander effects, two other forms of non-target effects (NTEs) have been identified in radiotherapy, as one is called cohort effects and the other is called abscopal effects. Cohort effects represent the phenomenon where irradiated cells can produce signals that reduce the survival of neighboring cells within an irradiated volume. The effects suggest the importance of cellular communication under irradiation with non-uniform dose distribution. In contrast, abscopal effects describe the NTEs that typically occur in non-irradiated cells distant from an irradiated target. These effects can be mediated primarily by immune cells such as T cells. Clinical trials have shown that application of radiation along with immunotherapy may enhance abscopal effects and improve therapeutic efficacy on non-target lesions outside an irradiated field. According to NTEs, cell viability is reduced not only by direct irradiation effects, but also due to signals emitted from nearby irradiated cells. A clinical consideration of NTEs could have a revolutionary impact on current radiotherapy via the establishment of more efficient and less toxic radiobiological models for treatment planning compared to conventional models. Thus, we will review the most updated findings about these effects and outline their mechanisms and potential applications in cancer treatment with a special focus on the brain, lung, and breast cancers.

SOD3 improves the tumor response to chemotherapy by stabilizing endothelial HIF-2α

One drawback of chemotherapy is poor drug delivery to tumor cells, due in part to hyperpermeability of the tumor vasculature. Extracellular superoxide dismutase (SOD3) is an antioxidant enzyme usually repressed in the tumor milieu. Here we show that specific SOD3 re-expression in tumor-associated endothelial cells (ECs) increases doxorubicin (Doxo) delivery into and chemotherapeutic effect on tumors. Enhanced SOD3 activity fostered perivascular nitric oxide accumulation and reduced vessel leakage by inducing vascular endothelial cadherin (VEC) transcription. SOD3 reduced HIF prolyl hydroxylase domain protein activity, which increased hypoxia-inducible factor-2α (HIF-2α) stability and enhanced its binding to a specific VEC promoter region. EC-specific HIF-2α ablation prevented both the SOD3-mediated increase in VEC transcription and the enhanced Doxo effect. SOD3, VEC, and HIF-2α levels correlated positively in primary colorectal cancers, which suggests a similar interconnection of these proteins in human malignancy.

Tumour vasculature influences drug delivery. Here, the authors show that SOD3 re-expression enhances doxorubicin delivery and effects through normalization of tumour vasculature via the HIF-2a/VE-cadherin pathway.

MicroRNA-21 Contributes to Reduced Microvascular Function in Binge Drinking Young Adults

BACKGROUND

Binge drinking is associated with increased risk for cardiovascular (CV) disease. MicroRNA-21 (miR21) is up-regulated in the setting of excessive alcohol consumption and CV disease. Therefore, the goal of this study was to examine the vasodilatory responses to flow and acetylcholine (ACh) in the absence and presence of an anti-miR21 inhibitor in the microcirculation of young adult repeated binge drinkers (BDs).

METHODS

Gluteal subcutaneous adipose tissue biopsies were obtained from young adults (18 to 30 years, n = 35 vessels from BDs and n = 28 vessels from abstainers). Resistance arteries (RAs) were isolated, incubated with anti-miR21 or a negative control (NC) to miR21 (12 hours; 50 nM), and lumen diameters measured with video microscopy. miR21 of adipose tissues was determined by quantitative polymerase chain reaction.

RESULTS

Flow-induced dilation and ACh-induced dilation (AChID) were reduced in BDs as compared to abstainers. The miR21 inhibitor but not the NC abrogated these effects in BDs, but did not affect vasodilation in abstainers. Nitric oxide synthase inhibition with L-NAME reduced vasodilation in abstainers but not in BDs. In BDs, vasodilation was reduced by L-NAME in the presence of anti-miR21 but not the NC. Scavenging the reactive oxygen species, hydrogen peroxide with polyethylene glycol catalase reduced dilation in BDs but did not affect the restored dilation by the miR21 inhibitor. Maximum dilation to papaverine (endothelium independent) was similar between groups and unaffected by pharmacological inhibition. Finally, vascular endogenous miR21 was increased in BDs compared to abstainers.

CONCLUSIONS

Endogenous miR21 is increased in RAs of young BDs, leading to reduced flow and AChID in the microcirculation.

TLR4/ROS/miRNA-21 pathway underlies lipopolysaccharide instructed primary tumor outgrowth in lung cancer patients

Activation of Toll-like receptor 4 (TLR4) signaling in human lung cancer with lipopolysaccharide (LPS) enhances tumor progression. However, whether primary human lung cancer outgrowth could respond to LPS and underlying mechanisms are unclear. Here we determined that TLR4 activation with LPS promoted outgrowth of primary human lung cancer cells in vitro and in vivo. Mechanistically, LPS stimulation increased expression levels of microRNA-21 (miR-21) in primary human lung cancer cells. Inhibition of miR-21 blocked the enhanced lung cancer growth induced by LPS in vitro and in vivo. Up-regulation of miR-21 promoted outgrowth of primary human lung cancer. Down-regulation of miR-21 limited primary human lung cancer outgrowth. Further, TLR4 activation in primary human lung cancer cells increased their ROS levels. Scavenge of ROS abrogated the up-regulation of miR-21 in primary human lung cancer cells and attenuated LPS-induced outgrowth. For in vivo relevance, expression of TLR4 was correlated with miR-21 expression and ROS production in freshly isolated, untreated primary human lung cancer cells. These findings demonstrate an essential role of TLR4/ROS/miR-21 pathway in LPS-induced outgrowth of primary human lung cancer. Our study connected a framework of innate signaling, oxidative stress and microRNA in tumor immunity and provided clues for developing new therapeutics for lung cancer.

Redox regulation of microRNAs in cancer

Dysregulation of microRNAs (miRNAs) has long been implicated in tumorigenesis, whereas the underlying mechanisms remain largely unknown. Oxidative stress is a hallmark of cancer that involved in multiple pathophysiological processes, including the aberrant regulation of miRNAs. Compelling evidences have implied complicated interplay between reactive oxygen species (ROS) and miRNAs. Indeed, ROS induces carcinogenesis through either reducing or increasing the miRNA level, leading to the activation of oncogenes or silence of tumor suppressors, respectively. In turn, miRNAs target ROS productive genes or antioxidant responsive elements to affect cellular redox balance, which contributes to establishing a microenvironment favoring cancer cell growth and metastasis. Both miRNAs and ROS have been identified as potential biomarkers and therapeutic targets in human malignancies, and comprehensive understanding of the molecular events herein will facilitate the development of novel cancer therapeutic strategies.

Extracellular superoxide dismutase and its role in cancer

Reactive oxygen species (ROS) are increasingly recognized as critical determinants of cellular signaling and a strict balance of ROS levels must be maintained to ensure proper cellular function and survival. Notably, ROS is increased in cancer cells. The superoxide dismutase family plays an essential physiological role in mitigating deleterious effects of ROS. Due to the compartmentalization of ROS signaling, EcSOD, the only superoxide dismutase in the extracellular space, has unique characteristics and functions in cellular signal transduction. In comparison to the other two intracellular SODs, EcSOD is a relatively new comer in terms of its tumor suppressive role in cancer and the mechanisms involved are less well understood. Nevertheless, the degree of differential expression of this extracellular antioxidant in cancer versus normal cells/tissues is more pronounced and prevalent than the other SODs. A significant association of low EcSOD expression with reduced cancer patient survival further suggests that loss of extracellular redox regulation promotes a conducive microenvironment that favors cancer progression. The vast array of mechanisms reported in mediating deregulation of EcSOD expression, function, and cellular distribution also supports that loss of this extracellular antioxidant provides a selective advantage to cancer cells. Moreover, overexpression of EcSOD inhibits tumor growth and metastasis, indicating a role as a tumor suppressor. This review focuses on the current understanding of the mechanisms of deregulation and tumor suppressive function of EcSOD in cancer.

MicroRNAs in Psychological Stress Reactions and Their Use as Stress-Associated Biomarkers, Especially in Human Saliva

MicroRNAs (miRNAs) play a central role in the regulation of many cellular processes including physiological and psychological stress reaction pathways. Psychological stress is an important factor for the genesis and maintenance of many diseases. Several miRNAs have already been described to be involved in its regulation. The presence of miRNAs in all body fluids implies a widespread role in communication throughout the whole organism and together with their stability makes them formidable candidates as biomarkers. Alterations of stress-associated miRNA expression levels have been found in the brain and whole blood of humans and animals. In this paper, we review the participation of miRNAs in stress-reactive processes as well as their usability as salivary biomarkers of such processes. In conclusion, we suggest that salivary miRNAs may be useful as noninvasive biomarkers to assess epigenetic regulation processes of chronic or acute psychological stress reactions.

Cardiovascular homeostasis dependence on MICU2, a regulatory subunit of the mitochondrial calcium uniporter

Hypertension increases the risk for development of abdominal aortic aneurysms, a silent pathology that is prone to rupture and cause sudden cardiac death. Male gender, smoking, and hypertension appear to increase risk for development of abdominal aortic aneurysms by provoking oxidative stress responses in cardiovascular tissues. Here we uncovered unexpected linkages between the calcium-sensing regulatory subunit MICU2 of the mitochondrial calcium uniporter and stress responses. We show that naive Micu2^−/− mice had abnormalities of cardiac relaxation but, with modest blood pressure elevation, developed abdominal aortic aneurysms with spontaneous rupture. These findings implicate mitochondrial calcium homeostasis as a critical pathway involved in protecting cardiovascular tissues from oxidative stress.

Comparative analyses of transcriptional profiles from humans and mice with cardiovascular pathologies revealed consistently elevated expression of MICU2, a regulatory subunit of the mitochondrial calcium uniporter complex. To determine if MICU2 expression was cardioprotective, we produced and characterized Micu2^−/− mice. Mutant mice had left atrial enlargement and Micu2^−/− cardiomyocytes had delayed sarcomere relaxation and cytosolic calcium reuptake kinetics, indicating diastolic dysfunction. RNA sequencing (RNA-seq) of Micu2^−/− ventricular tissues revealed markedly reduced transcripts encoding the apelin receptor (Micu2^−/− vs. wild type, P = 7.8 × 10⁻⁴⁰), which suppresses angiotensin II receptor signaling via allosteric transinhibition. We found that Micu2^−/− and wild-type mice had comparable basal blood pressures and elevated responses to angiotensin II infusion, but that Micu2^−/− mice exhibited systolic dysfunction and 30% lethality from abdominal aortic rupture. Aneurysms and rupture did not occur with norepinephrine-induced hypertension. Aortic tissue from Micu2^−/− mice had increased expression of extracellular matrix remodeling genes, while single-cell RNA-seq analyses showed increased expression of genes related to reactive oxygen species, inflammation, and proliferation in fibroblast and smooth muscle cells. We concluded that Micu2^−/− mice recapitulate features of diastolic heart disease and define previously unappreciated roles for Micu2 in regulating angiotensin II-mediated hypertensive responses that are critical in protecting the abdominal aorta from injury.

Effects of calcium channel on ovarian cancer cells

The aim of the present study was to examine the effects of calcium channel protein on ovarian cancer cells. The expression of calcium channel protein in normal ovarian cells and ovarian cancer cells was detected by fluorescence quantitative PCR. Subsequently, the ovarian cancer cells were added to calcium channel protein activator media at various concentrations of 0, 1, 4, 8, 12, 16 and 20 mmol/l. The concentration of calcium ion in different samples was produced, and using an MTT assay, ovarian cancer cell activity in various samples was detected. Finally, a flow cytometer was used to explore the apoptosis rate. It was found that there was a significant difference between the expression of calcium channel protein in normal ovarian tissue and ovarian cancer cells (P<0.05), as well as a significant difference of calcium concentration among various samples (P<0.05). When the concentrations of calcium channel activator were 1, 4, 8, 12, 16 and 20 mmol/l, the values of the ovarian cancer cell inhibition rates were 4.6, 21.3, 48.3, 67.9, 52.8 and 31.8%, respectively. It showed that the calcium channel activator inhibited the proliferation of ovarian cancer cells to a certain extent, in a dose-dependent manner, especially when the concentration was at 12 mmol/l at which the intracellular calcium concentration was similar to that in normal ovarian cells. In conclusion, calcium ions play an important role in promoting cell proliferation of ovarian cancer cells, and they were involved in apoptosis of ovarian cancer cells to some extent, which regulates apoptosis by controlling the content of intracellular calcium.

Understanding the role of CD44V6 in ovarian cancer

This study examined the association of CD44V6 expression in ovarian cancer. We recruited 38 patients with ovarian cancer, 23 with benign ovarian tumor, and 20 with normal ovaries using RT-PCR and western block analysis. Compared with normal ovaries, the expression of CD44V6 mRNA was significantly elevated in benign ovarian tumor and ovarian cancer. At the protein level, we found no significant differences in CD44V6 expression between normal ovarian tissue and benign ovarian tumor. However, the expression of CD44V6 in ovarian cancer was significantly elevated compared to normal ovaries and benign ovarian tumor. These results were supported by ELISA and western blot analysis. Immunohistochemistry showed that CD44V6 protein in ovarian cancer cells accumulated at high levels on the membrane of ovarian cancer cells. CD44V6 expression is closely associated with the tumorous transformation of ovarian tissue, suggesting that CD44V6 can promote the occurrence and progression of ovarian cancer.

Potential roles of microRNAs and ROS in colorectal cancer: diagnostic biomarkers and therapeutic targets

As one of the most commonly diagnosed cancers worldwide, colorectal adenocarcinoma often occurs sporadically in individuals aged 50 or above and there is an increase among younger patients under 50. Routine screenings are recommended for this age group to improve early detection. The multifactorial etiology of colorectal cancer consists of both genetic and epigenetic factors. Recently, studies have shown that the development and progression of colorectal cancer can be attributed to aberrant expression of microRNA. Reactive oxygen species (ROS) that play a key role in cancer cell survival, can also lead to carcinogenesis and cancer exacerbations. Given the rapid accumulating knowledge in the field, an updated review regarding microRNA and ROS in colorectal cancer is necessary. An extensive literature search has been conducted in PubMed/Medline databases to review the roles of microRNAs and ROS in colorectal cancer. Unique microRNA expression in tumor tissue, peripheral blood, and fecal samples from patients with colorectal cancer is outlined. Therapeutic approaches focusing on microRNA and ROS in colorectal cancer treatment is also delineated. This review aims to summarize the newest knowledge on the pathogenesis of colorectal cancer in the hopes of discovering novel diagnostic biomarkers and therapeutic techniques.

Kallistatin reduces vascular senescence and aging by regulating microRNA-34a-SIRT1 pathway

Kallistatin, an endogenous protein, protects against vascular injury by inhibiting oxidative stress and inflammation in hypertensive rats and enhancing the mobility and function of endothelial progenitor cells (EPCs). We aimed to determine the role and mechanism of kallistatin in vascular senescence and aging using cultured EPCs, streptozotocin (STZ)‐induced diabetic mice, and Caenorhabditis elegans (C. elegans). Human kallistatin significantly decreased TNF‐α‐induced cellular senescence in EPCs, as indicated by reduced senescence‐associated β‐galactosidase activity and plasminogen activator inhibitor‐1 expression, and elevated telomerase activity. Kallistatin blocked TNF‐α‐induced superoxide levels, NADPH oxidase activity, and microRNA‐21 (miR‐21) and p16^INK4a synthesis. Kallistatin prevented TNF‐α‐mediated inhibition of SIRT1, eNOS, and catalase, and directly stimulated the expression of these antioxidant enzymes. Moreover, kallistatin inhibited miR‐34a synthesis, whereas miR‐34a overexpression abolished kallistatin‐induced antioxidant gene expression and antisenescence activity. Kallistatin via its active site inhibited miR‐34a, and stimulated SIRT1 and eNOS synthesis in EPCs, which was abolished by genistein, indicating an event mediated by tyrosine kinase. Moreover, kallistatin administration attenuated STZ‐induced aortic senescence, oxidative stress, and miR‐34a and miR‐21 synthesis, and increased SIRT1, eNOS, and catalase levels in diabetic mice. Furthermore, kallistatin treatment reduced superoxide formation and prolonged wild‐type C. elegans lifespan under oxidative or heat stress, although kallistatin's protective effect was abolished in miR‐34 or sir‐2.1 (SIRT1 homolog) mutant C. elegans. Kallistatin inhibited miR‐34, but stimulated sir‐2.1 and sod‐3 synthesis in C. elegans. These in vitro and in vivo studies provide significant insights into the role and mechanism of kallistatin in vascular senescence and aging by regulating miR‐34a‐SIRT1 pathway.

Induction of miR-155 after Brain Injury Promotes Type 1 Interferon and has a Neuroprotective Effect

Traumatic brain injury (TBI) produces profound and lasting neuroinflammation that has both beneficial and detrimental effects. Recent evidence has implicated microRNAs (miRNAs) in the regulation of inflammation both in the periphery and the CNS. We examined the expression of inflammation associated miRNAs in the context of TBI using a mouse controlled cortical impact (CCI) model and found increased levels of miR-21, miR-223 and miR-155 in the hippocampus after CCI. The expression of miR-155 was elevated 9-fold after CCI, an increase confirmed by in situ hybridization (ISH). Interestingly, expression of miR-155 was largely found in neuronal nuclei as evidenced by co-localization with DAPI in MAP2 positive neurons. In miR-155 knock out (KO) mice expression of type I interferons IFNα and IFNβ, as well as IFN regulatory factor 1 and IFN-induced chemokine CXCL10 was decreased after TBI relative to wild type (WT) mice. Unexpectedly, miR-155 KO mice had increased levels of microglial marker Iba1 and increased neuronal degeneration as measured by fluoro-jade C (FJC) staining, suggesting a neuroprotective role for miR-155 in the context of TBI. This work demonstrates a role for miR-155 in regulation of the IFN response and neurodegeneration in the aftermath of TBI. While the presence of neuronal nuclear miRNAs has been described previously, their importance in disease states is relatively unknown. Here, we show evidence of dynamic regulation and pathological function of a nuclear miRNA in TBI.

MicroRNA-21 Mediates Angiotensin II-Induced Liver Fibrosis by Activating NLRP3 Inflammasome/IL-1β Axis via Targeting Smad7 and Spry1

AIMS

Angiotensin II (AngII), a vasoconstrictive peptide of the renin-angiotensin system (RAS), promotes hepatic fibrogenesis and induces microRNA-21(mir-21) expression. Angiotensin-(1-7) [Ang-(1-7)] is a peptide of the RAS, which attenuates liver fibrosis. Recently, it was reported that the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome participated in liver fibrosis. However, it remains unclear how mir-21 mediates AngII-induced NLRP3 inflammasome activation. We investigate the role of AngII-induced mir-21 in the regulation of NLRP3 inflammasome/IL-1β axis in liver fibrosis.

RESULTS

In vivo, circulating mir-21 was upregulated in patients with liver fibrosis and was positively correlated with liver fibrosis and oxidation. Treatment with Ang-(1-7) inhibited mir-21, NLRP3 inflammasome, and liver fibrosis after bile duct ligation (BDL) or AngII infusion. Inhibition of mir-21 suppressed the Smad7/Smad2/3/NOX4, Spry1/ERK/NF-κB pathway, NLRP3 inflammasome, and liver fibrosis induced by AngII infusion. In vitro, AngII upregulated mir-21 expression via targeting Smad7 and Spry1 in primary hepatic stellate cells (HSCs). In contrast, Ang-(1-7) suppressed mir-21 expression and oxidation induced by AngII. Overexpression of mir-21 promoted oxidation, and collagen production enhanced the effect of AngII on NLRP3 inflammasome activation via the Spry1/ERK/NF-κB, Smad7/Smad2/3/NOX4 pathways. However, downregulation of mir-21 exerted the opposite effects. Innovation and Conclusions: Mir-21 mediates AngII-activated NLRP3 inflammasome and resultant HSC activation via targeting Spry1 and Smad7. Ang-(1-7) protected against BDL or AngII infusion-induced hepatic fibrosis and inhibited mir-21 expression. Antioxid. Redox Signal. 27, 1-20.

Epigenetic regulation of TGF-β1 signalling in dilative aortopathy of the thoracic ascending aorta

The term 'epigenetics' refers to heritable, reversible DNA or histone modifications that affect gene expression without modifying the DNA sequence. Epigenetic modulation of gene expression also includes the RNA interference mechanism. Epigenetic regulation of gene expression is fundamental during development and throughout life, also playing a central role in disease progression. The transforming growth factor β1 (TGF-β1) and its downstream effectors are key players in tissue repair and fibrosis, extracellular matrix remodelling, inflammation, cell proliferation and migration. TGF-β1 can also induce cell switch in epithelial-to-mesenchymal transition, leading to myofibroblast transdifferentiation. Cellular pathways triggered by TGF-β1 in thoracic ascending aorta dilatation have relevant roles to play in remodelling of the vascular wall by virtue of their association with monogenic syndromes that implicate an aortic aneurysm, including Loeys-Dietz and Marfan's syndromes. Several studies and reviews have focused on the progression of aneurysms in the abdominal aorta, but research efforts are now increasingly being focused on pathogenic mechanisms of thoracic ascending aorta dilatation. The present review summarizes the most recent findings concerning the epigenetic regulation of effectors of TGF-β1 pathways, triggered by sporadic dilative aortopathy of the thoracic ascending aorta in the presence of a tricuspid or bicuspid aortic valve, a congenital malformation occurring in 0.5-2% of the general population. A more in-depth comprehension of the epigenetic alterations associated with TGF-β1 canonical and non-canonical pathways in dilatation of the ascending aorta could be helpful to clarify its pathogenesis, identify early potential biomarkers of disease, and, possibly, develop preventive and therapeutic strategies.

Role of Kallistatin Treatment in Aging and Cancer by Modulating miR-34a and miR-21 Expression

Kallistatin is an endogenous protein that regulates differential signaling pathways and a wide spectrum of biological activities via its two structural elements: an active site and a heparin-binding domain. Kallistatin via its heparin-binding site inhibits vascular inflammation and oxidative stress by antagonizing TNF-α-induced NADPH oxidase activity, NF-κB activation, and inflammatory gene expression in endothelial cells. Moreover, kallistatin via its active site inhibits microRNA-34a (miR-34a) synthesis and stimulates eNOS and SIRT1 expression in endothelial progenitor cells, whereas its heparin-binding site is crucial for blocking TNF-α-induced miR-21 expression and oxidative stress, thus reducing cellular senescence. By downregulating miR-34a and miR-21 expression, kallistatin treatment attenuates oxidative damage and aortic senescence in streptozotocin-induced diabetic mice and extends Caenorhabditis elegans lifespan under stress conditions. Likewise, kallistatin through the heparin-binding site inhibits TGF-β-induced miR-21 synthesis and oxidative stress in endothelial cells, resulting in inhibition of endothelial-mesenchymal transition, a process contributing to fibrosis and cancer. Furthermore, kallistatin's active site is essential for stimulating miR-34a and p53 expression and inhibiting the miR-21-Akt-Bcl-2 signaling pathway, thus inducing apoptosis in breast cancer cells. These findings reveal novel mechanisms of kallistatin in protection against senescence, aging, and cancer development by modulating miR-34a and miR-21 levels and inhibiting oxidative stress.

MiR-9-3p augments apoptosis induced by H2O2 through down regulation of Herpud1 in glioma

MicroRNAs are short, single-stranded non-coding RNA molecules that function as regulators of tumor progression in various cancers, including glioma. The present study sought to investigate the biological functions of miR-9-3p in glioma progression. The results of a microRNA microarray indicated that microRNA-9-3p (miR-9-3p, miR-9*) is down-regulated in high-grade (grades III and IV) gliomas compared with non-tumor tissues. These results were confirmed with real-time PCR. The miR-9-3p expression level was associated with age and tumor grade. Herpud1 was regulated by miR-9-3p in glioma cells and tissues and was identified as a miR-9-3p target with luciferase reporter assays. Glioma cells transfected with miR-9-3p mimics or HERPUD1-RNAi had more apoptotic cells than them in control after induced by H₂O₂. Our results indicated that low expression of miR-9-3p results in a high level of Herpud1, which may protect against apoptosis in glioma.

Impact of MicroRNAs in the Cellular Response to Hypoxia

In mammalian cells, hypoxia, or inadequate oxygen availability, regulates the expression of a specific set of MicroRNAs (MiRNAs), termed "hypoxamiRs." Over the past 10 years, the appreciation of the importance of hypoxamiRs in regulating the cellular adaptation to hypoxia has grown dramatically. At the cellular level, each hypoxamiR, including the master hypoxamiR MiR-210, can simultaneously regulate expression of multiple target genes in order to fine-tune the adaptive response of cells to hypoxia. This review addresses the complex molecular regulation of MiRNAs in both physiological and pathological conditions of low oxygen adaptation and the multiple functions of hypoxamiRs in various hypoxia-associated biological processes, including apoptosis, survival, proliferation, angiogenesis, inflammation, and metabolism. From a clinical perspective, we also discuss the potential use of hypoxamiRs as new biomarkers and/or therapeutic targets in cancer and aging-associated diseases including cardiovascular and fibroproliferative disorders.

Impact of microRNA dynamics on cancer hallmarks: An oral cancer scenario

MicroRNAs are endogenous small noncoding RNAs that negatively regulate gene expression at posttranscriptional level. The discovery of microRNAs has identified a new layer of gene regulation mechanisms, which play a pivotal role in development as well as in various cellular processes, such as proliferation, differentiation, cell growth, and cell death. Deregulated microRNA expression favors acquisition of cancer hallmark traits as well as transforms the tumor microenvironment, leading to tumor development and progression. Many recent studies have revealed altered expression of microRNAs in oral carcinoma with several microRNAs shown to have key biological role in tumorigenesis functioning either as tumor suppressors or as tumor promoters. MicroRNA expression levels correlate with clinicopathological variables and have a diagnostic and prognostic value in oral carcinoma. For these reasons, microRNA has been a hot topic in oral cancer research for the last few years. In this review, we attempt to summarize the present understanding of microRNA deregulation in oral carcinoma, their role in acquiring cancer hallmarks, and their potential diagnostic and prognostic value for oral cancer management.

Exosome-based immunomodulation during aging: A nano-perspective on inflamm-aging

Exosomes are nanovesicles formed by inward budding of endosomal membranes. They exert complex immunomodulatory effects on target cells, acting both as antigen-presenting vesicles and as shuttles for packets of information such as proteins, coding and non-coding RNA, and nuclear and mitochondrial DNA fragments. Albeit different, all such functions seem to be encompassed in the adaptive mechanism mediating the complex interactions of the organism with a variety of stressors, providing both for defense and for the evolution of symbiotic relationships with others organisms (gut microbiota, bacteria, and viruses). Intriguingly, the newly deciphered human virome and exosome biogenesis seem to share some physical-chemical characteristics and molecular mechanisms. Exosomes are involved in immune system recognition of self from non-self throughout life: they are therefore ideal candidate to modulate inflamm-aging, the chronic, systemic, age-related pro-inflammatory status, which influence the development/progression of the most common age-related diseases (ARDs). Not surprisingly, recent evidence has documented exosomal alteration during aging and in association with ARDs, even though data in this field are still limited. Here, we review current knowledge on exosome-based trafficking between immune cells and self/non-self cells (i.e. the virome), sketching a nano-perspective on inflamm-aging and on the mechanisms involved in health maintenance throughout life.

miR-21-mediated Radioresistance Occurs via Promoting Repair of DNA Double Strand Breaks

miR-21, as an oncogene that overexpresses in most human tumors, is involved in radioresistance; however, the mechanism remains unclear. Here, we demonstrate that miR-21-mediated radioresistance occurs through promoting repair of DNA double strand breaks, which includes facilitating both non-homologous end-joining (NHEJ) and homologous recombination repair (HRR). The miR-21-promoted NHEJ occurs through targeting GSK3B (a novel target of miR-21), which affects the CRY2/PP5 pathway and in turn increases DNA-PKcs activity. The miR-21-promoted HRR occurs through targeting both GSK3B and CDC25A (a known target of miR-21), which neutralizes the effects of targeting GSK3B-induced CDC25A increase because GSK3B promotes degradation of both CDC25A and cyclin D1, but CDC25A and cyclin D1 have an opposite effect on HRR. A negative correlation of expression levels between miR-21 and GSK3β exists in a subset of human tumors. Our results not only elucidate miR-21-mediated radioresistance, but also provide potential new targets for improving radiotherapy.

Redox Regulation of the Superoxide Dismutases SOD3 and SOD2 in the Pulmonary Circulation

When evaluating the role of redox-regulating signaling in pulmonary vascular diseases, it is intriguing to consider the modulation of key antioxidant enzymes like superoxide dismutase (SOD) because SOD isoforms are regulated by redox reactions, and, in turn, modulate downstream redox sensitive processes. The emerging field of redox biology is built upon understanding the regulation and consequences of tightly controlled and specific reduction-oxidation reactions that are critical for diverse cellular processes including cell signaling. Of relevance, both the site of production of specific reactive oxygen and nitrogen species and the site of the antioxidant defenses are highly compartmentalized within the cell. For example, superoxide is generated during oxidative phosphorylation in the mitochondria as well as by a number of enzymatic sources within the cytosol and at the cell membrane. In the pulmonary circulation, these sources include the mitochondrial electron transport chain, NADPH oxidases (NOX1-4, Duox1,2), nitric oxide synthases, and xanthine oxidase; this important topic has been thoroughly reviewed recently [1]. In parallel with these different cellular sites of superoxide production, the three SOD isoforms are also specifically localized to the cytosol (SOD1), mitochondria (SOD2) or extracellular compartment (SOD3). This chapter focuses on the role of redox mechanisms regulating SOD2 and SOD3, with an emphasis on these processes in the setting of pulmonary hypertension.

MicroRNA-19b-3p regulates nasopharyngeal carcinoma radiosensitivity by targeting TNFAIP3/NF-κB axis

Background

Nasopharyngeal carcinoma (NPC) is among the most common squamous cell carcinoma in South China and Southeast Asia. Radiotherapy is the primary treatment for NPC. However, radioresistance acts as a significant factor that limits the efficacy of radiotherapy for NPC patients. Growing evidence supports that microRNAs (miRNAs) play an important role in radiation response.

Methods

Real-time quantitative PCR was used to analyze the expression of miR-19b-3p in NPC cell lines and NP69. miR-19b-3p expression profiles in NPC tissues were obtained from the Gene Expression Omnibus database. The effect of miR-19b-3p on radiosensitivity was evaluated by cell viability assays, colony formation assays and in vivo experiment. Apoptosis and cell cycle were examined by flow cytometry. Luciferase reporter assay was used to assess the target genes of miR-19b-3p. Expression of target proteins and downstream molecules were analyzed by Western blot.

Results

miR-19b-3p was upregulated in NPC and served as an independent predictor for reduced patient survival. Radioresponse assays showed that miR-19b-3p overexpression resulted in decreased sensitivity to irradiation, whereas miR-19b-3p downregulation resulted in increased sensitivity to irradiation in vitro. Moreover, miR-19b-3p decreased the sensitivity of NPC cells to irradiation in vivo. Luciferase reporter assay confirmed that TNFAIP3 was a direct target gene of miR-19b-3p. Knockdown of TNFAIP3 reduced sensitivity to irradiation, whereas upregulation of TNFAIP3 expression reversed the inhibitory effects of miR-19b-3p on NPC cell radiosensitivity. Mechanistically, we found that miR-19b-3p increased NPC cell radioresistance by activating the TNFAIP3/ NF-κB axis.

Conclusions

miR-19b-3p contributes to the radioresistance of NPC by activating the TNFAIP3/ NF-κB axis. miR-19b-3p is a determinant of NPC radioresponse and may serve as a potential therapeutic target in NPC treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0465-1) contains supplementary material, which is available to authorized users.

Insights into the Regulatory Role of Non-coding RNAs in Cancer Metabolism

Cancer represents a complex disease originated from alterations in several genes leading to disturbances in important signaling pathways in tumor biology, favoring heterogeneity that promotes adaptability and pharmacological resistance of tumor cells. Metabolic reprogramming has emerged as an important hallmark of cancer characterized by the presence of aerobic glycolysis, increased glutaminolysis and fatty acid biosynthesis, as well as an altered mitochondrial energy production. The metabolic switches that support energetic requirements of cancer cells are closely related to either activation of oncogenes or down-modulation of tumor-suppressor genes, finally leading to dysregulation of cell proliferation, metastasis and drug resistance signals. Non-coding RNAs (ncRNAs) have emerged as one important kind of molecules that can regulate altered genes contributing, to the establishment of metabolic reprogramming. Moreover, diverse metabolic signals can regulate ncRNA expression and activity at genetic, transcriptional, or epigenetic levels. The regulatory landscape of ncRNAs may provide a new approach for understanding and treatment of different types of malignancies. In this review we discuss the regulatory role exerted by ncRNAs on metabolic enzymes and pathways involved in glucose, lipid, and amino acid metabolism. We also review how metabolic stress conditions and tumoral microenvironment influence ncRNA expression and activity. Furthermore, we comment on the therapeutic potential of metabolism-related ncRNAs in cancer.

Striatal Mitochondrial Disruption following Severe Traumatic Brain Injury

Traumatic brain injury (TBI) results in oxidative stress and calcium dysregulation in mitochondria. However, little work has examined perturbations of mitochondrial homeostasis in peri-injury tissue. We examined mitochondrial homeostasis after a unilateral controlled cortical impact over the sensorimotor cortex in adult male rats. There was a significant reduction in peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) messenger RNA (mRNA) at post-injury days 3 and 6 and a transient reduction in mitochondrial DNA copy number at 3 days post-injury that recovered by 6 days in the ipsi-injury striatum. In ipsilateral cortex, PGC-1α mRNA was reduced only at 6 days post-injury. Additionally, expression of mitochondrial-encoded mRNAs, cytochrome c oxidase subunit 1 and NADH dehydrogenase subunit 1, was decreased at 3 and 6 days post-injury in ipsilesional striatum and at 6 days post-injury in ipsilesional cortex. There was no observable decrease in nuclear-encoded mRNAs mitochondrial transcription factor A or NADH dehydrogenase (ubiquinone) Fe-S protein 1. We detected an acute increase in superoxide dismutase 2 mRNA expression, as well as an induction of microRNA (miR)-21 and miR-155, which have been previously demonstrated to disrupt mitochondrial homeostasis. Behaviorally, rats with TBI exhibited marked error rates in contrainjury forelimb performance on the ladder test. These findings reveal that there may be differential susceptibilities of various peri-injury brain structures to mitochondrial dysfunction and associated behavioral deficits, and that molecular pathways demonstrated to interfere with mitochondrial homeostasis and function are activated subacutely post-TBI.

Quercetin inhibits Cr(VI)-induced malignant cell transformation by targeting miR-21-PDCD4 signaling pathway

Hexavalent chromium [Cr(VI)] is an important human carcinogen associated with pulmonary diseases and lung cancer. Inhibition of Cr(VI)-induced carcinogenesis by a dietary antioxidant is a novel approach. Quercetin is one of the most abundant dietary flavonoids widely present in many fruits and vegetables, possesses potent antioxidant and anticancer properties. MicroRNA-21 (miR-21) is a key oncomiR significantly elevated in the majority of human cancers that exerts its oncogenic activity by targeting the tumor suppressor gene programmed cell death 4 (PDCD4). The present study examined the effect of quercetin on the inhibition of Cr(VI)-induced malignant cell transformation and the role of miR-21-PDCD4 signaling involved. Our results showed that quercetin decreased ROS generation induced by Cr(VI) exposure in BEAS-2B cells. Chronic Cr(VI) exposure induced malignant cell transformation, increased miR-21 expression and caused inhibition of PDCD4, which were significantly inhibited by the treatment of quercetin in a dose dependent manner. Nude mice injected with BEAS-2B cells chronically exposed to Cr(VI) in the presence of quercetin showed reduced tumor incidence compared to Cr(VI) alone treated group. Stable knockdown of miR-21 and overexpression of PDCD4 or catalase in BEAS-2B cells suppressed Cr(VI)-induced malignant transformation and tumorigenesis. Taken together, these results demonstrate that quercetin is able to protect BEAS-2B cells from Cr(VI)-induced carcinogenesis by targeting miR-21-PDCD4 signaling.

Lessons learned using different mouse models during space radiation-induced lung tumorigenesis experiments

Unlike terrestrial ionizing radiation, space radiation, especially galactic cosmic rays (GCR), contains high energy charged (HZE) particles with high linear energy transfer (LET). Due to a lack of epidemiologic data for high-LET radiation exposure, it is highly uncertain how high the carcinogenesis risk is for astronauts following exposure to space radiation during space missions. Therefore, using mouse models is necessary to evaluate the risk of space radiation-induced tumorigenesis; however, which mouse model is better for these studies remains uncertain. Since lung tumorigenesis is the leading cause of cancer death among both men and women, and low-LET radiation exposure increases human lung carcinogenesis, evaluating space radiation-induced lung tumorigenesis is critical to enable safe Mars missions. Here, by comparing lung tumorigenesis obtained from different mouse strains, as well as miR-21 in lung tissue/tumors and serum, we believe that wild type mice with a low spontaneous tumorigenesis background are ideal for evaluating the risk of space radiation-induced lung tumorigenesis, and circulating miR-21 from such mice model might be used as a biomarker for predicting the risk.

Extracellular Superoxide Dismutase: Growth Promoter or Tumor Suppressor?

Extracellular superoxide dismutase (SOD3) gene transfer to tissue damage results in increased healing, increased cell proliferation, decreased apoptosis, and decreased inflammatory cell infiltration. At molecular level, in vivo SOD3 overexpression reduces superoxide anion (O₂⁻) concentration and increases mitogen kinase activation suggesting that SOD3 could have life-supporting characteristics. The hypothesis is further strengthened by the observations showing significantly increased mortality in conditional knockout mice. However, in cancer SOD3 has been shown to either increase or decrease cell proliferation and survival depending on the model system used, indicating that SOD3-derived growth mechanisms are not completely understood. In this paper, the author reviews the main discoveries in SOD3-dependent growth regulation and signal transduction.

Antioxidants inhibit advanced glycosylation end-product-induced apoptosis by downregulation of miR-223 in human adipose tissue-derived stem cells

Advanced glycosylation end products (AGEs) are endogenous inflammatory mediators that induce apoptosis of mesenchymal stem cells. A potential mechanism includes increased generation of reactive oxygen species (ROS). MicroRNA-223 (miR-223) is implicated in the regulation of cell growth and apoptosis in several cell types. Here, we tested the hypothesis that antioxidants N-acetylcysteine (NAC) and ascorbic acid 2-phosphate (AAP) inhibit AGE-induced apoptosis via a microRNA-dependent mechanism in human adipose tissue-derived stem cells (ADSCs). Results showed that AGE-HSA enhanced apoptosis and caspase-3 activity in ADSCs. AGE-HSA also increased ROS generation and upregulated the expression of miR-223. Interestingly, reductions in ROS generation and apoptosis, and upregulation of miR-223 were found in ADSCs treated with antioxidants NAC and AAP. Furthermore, miR-223 mimics blocked antioxidant inhibition of AGE-induced apoptosis and ROS generation. Knockdown of miR-223 amplified the protective effects of antioxidants on apoptosis induced by AGE-HSA. miR-223 acted by targeting fibroblast growth factor receptor 2. These results indicate that NAC and AAP suppress AGE-HSA-induced apoptosis of ADSCs, possibly through downregulation of miR-223.

Glyoxalase I drives epithelial-to-mesenchymal transition via argpyrimidine-modified Hsp70, miR-21 and SMAD signalling in human bronchial cells BEAS-2B chronically exposed to crystalline silica Min-U-Sil 5: Transformation into a neoplastic-like phenotype

Glyoxalase I (Glo1) is the main scavenging enzyme of methylglyoxal (MG), a potent precursor of advanced glycation end products (AGEs). AGEs are known to control multiple biological processes, including epithelial to mesenchymal transition (EMT), a multistep phenomenon associated with cell transformation, playing a major role in a variety of diseases, including cancer. Crystalline silica is a well-known occupational health hazard, responsible for a great number of human pulmonary diseases, such as silicosis. There is still much debate concerning the carcinogenic role of crystalline silica, mainly due to the lack of a causal demonstration between silica exposure and carcinogenesis. It has been suggested that EMT might play a role in crystalline silica-induced lung neoplastic transformation. The aim of this study was to investigate whether, and by means of which mechanism, the antiglycation defence Glo1 is involved in Min-U-Sil 5 (MS5) crystalline silica-induced EMT in BEAS-2B human bronchial epithelial cells chronically exposed, and whether this is associated with the beginning of a neoplastic-like transformation process. By using gene silencing/overexpression and scavenging/inhibitory agents, we demonstrated that MS5 induced hydrogen peroxide-mediated c-Jun-dependent Glo1 up-regulation which resulted in a decrease in the Argpyrimidine-modified Hsp70 protein level which triggered EMT in a novel mechanism involving miR-21 and SMAD signalling. The observed EMT was associated with a neoplastic-like phenotype. The results obtained provide a causal in vitro demonstration of the MS5 pro-carcinogenic transforming role and more importantly they provide new insights into the mechanisms involved in this process, thus opening new paths in research concerning the in vivo study of the carcinogenic potential of crystalline silica.

Interplay between Reactive oxygen Species and MicroRNAs in Cancer

Since both reactive oxygen species (ROS) production and microRNAs expression signature have been associated with tumor development, progression, metastasis and therapeutic response, it is important to understand the crosstalk between ROS and microRNAs. Indeed, growing evidence suggests a reciprocal connection between ROS signaling and microRNAs pathway, resulting in diverse biological effects in cancer cells. In this mini review, we discussed the ROS-responsive microRNAs that have implications in cancer and the possible mechanisms in which ROS regulate microRNAs. We also highlighted the microRNAs which are able to modify cellular ROS homeostasis during tumorigenesis, their biological targets and subsequent functions. As the use of antioxidants is limited due to the diverse or even opposing roles of ROS signaling in cancer, the discovery of ROS-responsive microRNAs provides a potential new strategy to specifically overcome ROS-mediated tumor progression or benefit from ROS-induced apoptosis.

Inhibition of colon cancer growth by docosahexaenoic acid involves autocrine production of TNFα

The omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) has anti-inflammatory and anti-cancer properties. Among pro-inflammatory mediators, tumor necrosis factor α (TNFα) plays a paradoxical role in cancer biology with induction of cancer cell death or survival depending on the cellular context. The objective of the study was to evaluate the role of TNFα in DHA-mediated tumor growth inhibition and colon cancer cell death. The treatment of human colorectal cancer cells, HCT-116 and HCT-8 cells, with DHA triggered apoptosis in autocrine TNFα-dependent manner. We demonstrated that DHA-induced increased content of TNFα mRNA occurred through a post-transcriptional regulation via the down-regulation of microRNA-21 (miR-21) expression. Treatment with DHA led to nuclear accumulation of Foxo3a that bounds to the miR-21 promoter triggering its transcriptional repression. Moreover, inhibition of RIP1 kinase and AMP-activated protein kinase α reduced Foxo3a nuclear-cytoplasmic shuttling and subsequent increase of TNFα expression through a decrease of miR-21 expression in DHA-treated colon cancer cells. Finally, we were able to show in HCT-116 xenograft tumor-bearing nude mice that a DHA-enriched diet induced a decrease of human miR-21 expression and an increase of human TNFα mRNA expression limiting tumor growth in a cancer cell-derived TNFα dependent manner. Altogether, the present work highlights a novel mechanism for anti-cancer action of DHA involving colon cancer cell death mediated through autocrine action of TNFα.

Regulation of hypoxia-inducible factor-1a by reactive oxygen species: new developments in an old debate

Hypoxia-Inducible Factor-1 (HIF-1) has been largely studied for its role in cell survival in hypoxic conditions. The regulation of HIF-1 is a complex process and involves a number of molecules and pathways. Among these mechanisms a direct regulatory role of reactive oxygen species (ROS) on HIF-1 alpha subunit has received a great deal of attention and the existing body of literature includes many contradictory findings. Other intermediates such as nitric oxide (NO), specific microRNAs (miR), and transcriptional and post-translational modification have also been implicated as players in ROS mediated HIF-1a regulation. The focus of this review is to present the past conflicting evidence along with more recent findings in order to relate various aspects of this complex process. Aside from the direct role of ROS on HIF-1a regulation under hypoxia and normoxia, we analyzed the effect of different sources and concentrations of NO and the interplay between superoxide (SO) and NO in this process. We also present findings on transcriptional and translational regulation of HIF-1a via ROS and the interplay with microRNAs in this process. This review further provides insight on ERK and PI3K/AKT signaling as a common mechanism relating several pathways of ROS mediated HIF-1a regulation. Ultimately further research and discovery regarding HIF-1 regulation by oxidative stress is warranted for better understanding of disease development and potential therapeutics for pathologies such as cancer, inflammatory diseases, and ischemia-reperfusion injury.