Inflammation regulates microRNA expression in cooperation with p53 and nitric oxide

N-Acetylcysteine and Atherosclerosis: Promises and Challenges

Atherosclerosis remains a leading cause of cardiovascular diseases. Although the mechanism for atherosclerosis is complex and has not been fully understood, inflammation and oxidative stress play a critical role in the development and progression of atherosclerosis. N-acetylcysteine (NAC) has been used as a mucolytic agent and an antidote for acetaminophen overdose with a well-established safety profile. NAC has antioxidant and anti-inflammatory effects through multiple mechanisms, including an increase in the intracellular glutathione level and an attenuation of the nuclear factor kappa-B mediated production of inflammatory cytokines like tumor necrosis factor-alpha and interleukins. Numerous animal studies have demonstrated that NAC significantly decreases the development and progression of atherosclerosis. However, the data on the outcomes of clinical studies in patients with atherosclerosis have been limited and inconsistent. The purpose of this review is to summarize the data on the effect of NAC on atherosclerosis from both pre-clinical and clinical studies and discuss the potential mechanisms of action of NAC on atherosclerosis, as well as challenges in the field.

Oxidative Stress and Epigenetics: miRNA Involvement in Rare Autoimmune Diseases

Autoimmune diseases (ADs) such as Sjögren’s syndrome, Kawasaki disease, and systemic sclerosis are characterized by chronic inflammation, oxidative stress, and autoantibodies, which cause joint tissue damage, vascular injury, fibrosis, and debilitation. Epigenetics participate in immune cell proliferation and differentiation, which regulates the development and function of the immune system, and ultimately interacts with other tissues. Indeed, overlapping of certain clinical features between ADs indicate that numerous immunologic-related mechanisms may directly participate in the onset and progression of these diseases. Despite the increasing number of studies that have attempted to elucidate the relationship between miRNAs and oxidative stress, autoimmune disorders and oxidative stress, and inflammation and miRNAs, an overall picture of the complex regulation of these three actors in the pathogenesis of ADs has yet to be formed. This review aims to shed light from a critical perspective on the key AD-related mechanisms by explaining the intricate regulatory ROS/miRNA/inflammation axis and the phenotypic features of these rare autoimmune diseases. The inflamma-miRs miR-155 and miR-146, and the redox-sensitive miR miR-223 have relevant roles in the inflammatory response and antioxidant system regulation of these diseases. ADs are characterized by clinical heterogeneity, which impedes early diagnosis and effective personalized treatment. Redox-sensitive miRNAs and inflamma-miRs can help improve personalized medicine in these complex and heterogeneous diseases.

Regulation of pleiotropic physiological roles of nitric oxide signaling

Nitric Oxide (NO) is a highly diffusible, ubiquitous signaling molecule and a free radical that is naturally synthesized by our body. The pleiotropic effects of NO in biological systems are due to its reactivity with different molecules, such as molecular oxygen (O₂), superoxide anion, DNA, lipids, and proteins. There are several contradictory findings in the literature pertaining to its role in oncology. NO is a Janus-faced molecule shown to have both tumor promoting and tumoricidal effects, which depend on its concentration, duration of exposure, and location. A high concentration is shown to have cytotoxic effects by triggering apoptosis, and at a low concentration, NO promotes angiogenesis, metastasis, and tumor progression. Upregulated NO synthesis has been implicated as a causal factor in several pathophysiological conditions including cancer. This dichotomous effect makes it highly challenging to discover its true potential in cancer biology. Understanding the mechanisms by which NO acts in different cancers helps to develop NO based therapeutic strategies for cancer treatment. This review addresses the physiological role of this molecule, with a focus on its bimodal action in various types of cancers.

Gut Microbiota-MicroRNA Interactions in Intestinal Homeostasis and Cancer Development

Pre-clinical models and clinical studies highlight the significant impact of the host-microbiota relationship on cancer development and treatment, supporting the emerging trend for a microbiota-based approach in clinical oncology. Importantly, the presence of polymorphic microbes is considered one of the hallmarks of cancer. The epigenetic regulation of gene expression by microRNAs affects crucial biological processes, including proliferation, differentiation, metabolism, and cell death. Recent evidence has documented the existence of bidirectional gut microbiota-microRNA interactions that play a critical role in intestinal homeostasis. Importantly, alterations in microRNA-modulated gene expression are known to be associated with inflammatory responses and dysbiosis in gastrointestinal disorders. In this review, we summarize the current findings about miRNA expression in the intestine and focus on specific gut microbiota-miRNA interactions linked to intestinal homeostasis, the immune system, and cancer development. We discuss the potential clinical utility of fecal miRNA profiling as a diagnostic and prognostic tool in colorectal cancer, and demonstrate how the emerging trend of gut microbiota modulation, together with the use of personalized microRNA therapeutics, might bring improvements in outcomes for patients with gastrointestinal cancer in the era of precision medicine.

Expression and Biological Functions of miRNAs in Chronic Pain: A Review on Human Studies

Chronic pain is a major public health problem and an economic burden worldwide. However, its underlying pathological mechanisms remain unclear. MicroRNAs (miRNAs) are a class of small noncoding RNAs that post-transcriptionally regulate gene expression and serve key roles in physiological and pathological processes. This review aims to synthesize the human studies examining miRNA expression in the pathogenesis of chronic primary pain and chronic secondary pain. Additionally, to understand the potential pathophysiological impact of miRNAs in these conditions, an in silico analysis was performed to reveal the target genes and pathways involved in primary and secondary pain and their differential regulation in the different types of chronic pain. The findings, methodological issues and challenges of miRNA research in the pathophysiology of chronic pain are discussed. The available evidence suggests the potential role of miRNA in disease pathogenesis and possibly the pain process, eventually enabling this role to be exploited for pain monitoring and management.

Expression of Selected microRNAs in Migraine: A New Class of Possible Biomarkers of Disease?

Preliminary but convergent findings suggest a role for microRNAs (miRNAs) in the generation and maintenance of chronic pain and migraine. Initial observations showed that serum levels of miR-382-5p and miR-34a-5p expression were increased in serum during the migraine attack, with miR-382-5p increasing in the interictal phase as well. By contrast, miR-30a-5p levels were lower in migraine patients compared to healthy controls. Of note, antimigraine treatments proved to be capable of influencing the expression of these miRNAs. Altogether, these observations suggest that miRNAs may represent migraine biomarkers, but several points are yet to be elucidated. A major concern is that these miRNAs are altered in a broad spectrum of painful and non-painful conditions, and thus it is not possible to consider them as truly “migraine-specific” biomarkers. We feel that these miRNAs may represent useful tools to uncover and define different phenotypes across the migraine spectrum with different treatment susceptibilities and clinical features, although further studies are needed to confirm our hypothesis. In this narrative review we provide an update and a critical analysis of available data on miRNAs and migraines in order to propose possible interpretations. Our main objective is to stimulate research in an area that holds promise when it comes to providing reliable biomarkers for theoretical and practical scientific advances.

miR‑34a increases inflammation and oxidative stress levels in patients with necrotizing enterocolitis by downregulating SIRT1 expression

The miR‑34a/SIRT1 signaling axis is an important signaling axis in tumors and diseases. Notably, low SIRT1 expression in the intestinal tissues of patients with necrotizing enterocolitis (NEC) has been reported. However, whether miR‑34a/SIRT1 signaling as a target to protect the intestines during the NEC process is unclear and remains to be elucidated. Blood samples were collected from 30 patients with NEC, and an NEC rat model was used. The miR‑34a and SIRT1 gene and protein expression levels were assayed by qPCR and Western blotting method. The inflammatory cytokine levels and oxidative stress levels were detected using the ELISA method. The results demonstrated that birth weight, albumin and glucose concentrations were significantly decreased in the NEC patient group compared with the control group, but the C‑reactive protein (CRP) and procalcitonin (PCT) concentrations were significantly increased. The miR‑34a expression level was notably increased in the NEC group, but the SIRT1 expression level was markedly decreased. Notably, the miR‑34a was significantly correlated with NEC severity and the concentrations of CRP, PCT, IL‑6, TNF‑α, IL‑1β, IL‑8, MCP‑1, VCAM1 and malondialdehyde (MDA), but was significantly negatively correlated with SIRT1 gene expression and the concentration of IL‑10. Intestinal villi damage in NEC rats was decreased with miR‑34a inhibition and SIRT1 activation treatment by decreasing the levels of inflammatory cytokines, including IL‑6, TNF‑α, IL‑1β and IL‑8, and oxidative stress proteins, including MCP‑1, VCAM1, and MDA, as well as increasing the level of the anti‑inflammatory cytokine IL‑10. In addition, the results indicated that miR‑34a inhibition and SIRT1 activation strongly protected the intestine and decreased the damage caused by NEC, not only by decreasing the protein levels of SIRT1, TNF‑α, IL‑1β, IL‑6 and IL‑8, but also by increasing the IL‑10 protein levels. The miR‑34a inhibition and SIRT1 activation may decrease the damage caused by NEC by decreasing proinflammatory cytokines and oxidative stress proteins and by increasing the anti‑inflammatory cytokine pathway. Based on the aforementioned analysis, the miR‑34a and SIRT1 proteins may be potential novel therapeutic targets in NEC.

Role of Nitric Oxide in Gene Expression Regulation during Cancer: Epigenetic Modifications and Non-Coding RNAs

Nitric oxide (NO) has been identified and described as a dual mediator in cancer according to dose-, time- and compartment-dependent NO generation. The present review addresses the different epigenetic mechanisms, such as histone modifications and non-coding RNAs (ncRNAs), miRNA and lncRNA, which regulate directly or indirectly nitric oxide synthase (NOS) expression and NO production, impacting all hallmarks of the oncogenic process. Among lncRNA, HEIH and UCA1 develop their oncogenic functions by inhibiting their target miRNAs and consequently reversing the inhibition of NOS and promoting tumor proliferation. The connection between miRNAs and NO is also involved in two important features in cancer, such as the tumor microenvironment that includes key cellular components such as tumor-associated macrophages (TAMs), cancer associated fibroblasts (CAFs) and cancer stem cells (CSCs).

MALAT1 rs619586 A/G polymorphisms are associated with decreased risk of lung cancer

Lung cancer is the leading cause of cancer-associated mortality worldwide. Genetic factors are reported to play important roles in lung carcinogenesis. To evaluate genetic susceptibility, we conducted a hospital-based case-control study on the effects of functional single nucleotide polymorphisms (SNPs) in long non-coding RNAs (lncRNAs) and microRNAs on lung cancer development. A total of 917 lung cancer cases and 925 control subjects were recruited. The MALAT1 rs619586 A/G genotype frequencies between patient and control groups were significantly different (P < .001), specifically, 83.85% vs 75.88% (AA), 15.60% vs 21.79% (AG), and 0.55% vs 2.32% (GG). When the homozygous genotype MALAT1 rs619586 AA was used as the reference group, AG (AG vs AA: adjusted odds ratio [OR] 0.65, 95% confidential interval [CI] 0.51-0.83, P = .001) and GG genotypes were associated with significantly decreased risk of lung cancer (GG vs AA: adjusted OR 0.22, 95% CI 0.08-0.59, P = .003). In the dominant model, MALAT1 rs619586 AG/GG variants were also associated with a significantly decreased risk of lung cancer (adjusted OR 0.61, 95% CI 0.48-0.78, P < .001). In the recessive model, when MALAT1 rs619586 AA/AG genotypes were used as the reference group, the GG homozygous genotype was also associated with significantly decreased risk for lung cancer (adjusted OR 0.24, 95% CI 0.09-0.64, P = .004). Hsa-miR-34b/c rs4938723 T > C, pri-miR-124-1 rs531564 C > G and hsa-miR-423 rs6505162 C > A SNPs were not associated with lung cancer risk. Our collective data indicated that MALAT1 rs619586 A/G SNPs significantly reduced the risk of lung cancer. Large-scale studies on different ethnic populations and tissue-specific biological characterization are required to validate the current findings.

The molecular mechanisms of lithium-induced cardiotoxicity in male rats and its amelioration by N-acetyl cysteine

Lithium is one of the most powerful and commonly used medications for the treatment of various psychiatric diseases, especially bipolar disorder. However, it has a narrow therapeutic index with toxic effects on various organs. There are several case reports of lithium-induced arrhythmia and ischemia. The current work aimed to study the toxic effects of lithium on the heart of adult albino rats and its molecular mechanisms and the ameliorating effect of N-acetyl cysteine (NAC). Sixty adult male Wistar albino rats were classified into four groups; control, NAC-treated received NAC 500 mg/kg/week dissolved in 1 ml 0.9% sodium chloride intraperitoneal, lithium-treated received 52.5 mg/kg/day of lithium carbonate dissolved in 1 ml 0.9% sodium chloride orally by gavage, and lithium-and-NAC-treated (group IV) received lithium and NAC in the previous doses. After 12 weeks, the rats of group III showed a significant accumulation of ascites and a decrease in the mean arterial blood pressure and electrocardiographic (ECG) findings of ischemia and arrhythmia. In addition, there was an elevation in cardiac biomarkers creatine kinase MB (CK-MB), cardiac troponin I (cTnI), and several histological lesions with a significant increase in the area % of Van Gieson, endothelial nitric oxide synthase (eNOS), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) immunoreaction. There was significant upregulation of microRNA-1, microRNA-21 (miRNA-21), and microRNA-29 (miRNA-29). MiRNA-21 was strongly positively correlated to the area % of 8-OHdG, while miRNA-29 was strongly positively correlated to the area % of Van Gieson staining. NAC significantly improved the cardiotoxic effects of lithium. Being a nontoxic and safe antioxidant, NAC can be used to ameliorate lithium-induced cardiac injury.

Altered expression of miR-181 affects cell fate and targets drug resistance-related mechanisms

MicroRNAs (miRNAs) are non-coding transcripts which regulate genetic and epigenetic events by interfering with mRNA translation. miRNAs are involved in regulation of cell fate due to their ability of interfering with physiological or pathological processes. In this review paper, we evaluate the role of miR-181 family members as prognostic or diagnostic markers or therapeutic targets in malignant pathologies in connection with the main hallmarks of cancer that are modulated by the family. Also, we take over the dual role of this family in dependency with the tumour suppressor and oncogenic features presented in cell and cancer type specific manner. Restoration of the altered expression levels contributes to the activation of cell death pathways or to a reduction in the invasion and migration mechanism; moreover, the mechanism of drug resistance is also modulated by miR-181 sequences with important applications in therapeutic strategies for malignant cells sensitisation. Overall, the main miR-181 family regulatory mechanisms are presented in a cancer specific context, emphasizing the possible clinical application of this family in terms of novel diagnosis and therapy approaches.

Pri-miR-34b/c rs4938723 Polymorphism Contributes to Coronary Artery Disease Susceptibility

OBJECTIVES

Accumulating evidences have shown that polymorphisms in miRNA genes play an important role in the susceptibility to coronary artery disease (CAD). A potentially functional polymorphism rs4938723, which located within the promoter region of pri-miR-34b/c, may affect the expression of miR-34b/c. To date, the role of genetic variant in pri-miR-34b/c on CAD risk is still unknown. Here we aimed to evaluate the association of Pri-miR-34b/c rs4938723 polymorphism with individual susceptibility to CAD in a Chinese Han population.

METHODS

Genotyping was performed in a case-control study of 563 patients and 646 controls using polymerase chain reaction-ligase detection reaction (PCR-LDR) method. The association of rs4938723 with CAD risk was evaluated using logistic regression analysis with SPSS software.

RESULTS

We found that the C allele of pri-miR-34b/c rs4938723 was significantly associated with a decreased risk of CAD when compared with the T allele (OR = 0.76, 95% CI = 0.62-0.95, p = 0.015). Consistently, compared with those carrying TT genotype, the CC homozygotes displayed significantly reduced risk for CAD (OR = 0.54, 95% CI = 0.32-0.91, p = 0.021). Similar trend of the reduced risk for CAD was detected when the CT and CC genotypes were combined (OR = 0.75, 95% CI = 0.57-0.99, p = 0.044). Stratified analysis of pri-miR-34b/c rs4938723 revealed a more significant association of C allele with decreased CAD risk among older subjects, male and non-smokers.

CONCLUSIONS

Our findings suggest that the pri-miR-34b/c rs4938723 polymorphism is associated with CAD susceptibility in the Chinese Han population. Further studies are warranted to confirm the general validity of our findings.

One step ahead: miRNA-34 in colon cancer-future diagnostic and therapeutic tool?

The discovery that microRNAs (miRNAs) - short, non-coding RNA molecules which regulate gene expression - are implicated in many types of cancer has revolutionised cancer research, giving hope for a new perspective in diagnostics and treatment. Dysregulation of miRNAs occurs in various malignancies, including colorectal cancer (CRC). CRC is one of the leading causes of cancer-related death and in most countries its incidence is still rising. Among several miRNAs which have been linked to CRC, miR-34 has attracted particular attention. This miRNA is involved in the regulation of cell cycle and apoptosis through multiple signaling pathways such as p53, Ra and Wnt signaling. Understanding its role in CRC may facilitate its future use as a diagnostic tool and therapeutic target.

Design, Development and Construct Validation of the Children's Dietary Inflammatory Index

OBJECTIVE

To design and validate a literature-derived, population-based Children's Dietary Inflammatory Index (C-DII)^TM.

DESIGN

The C-DII was developed based on a review of literature through 2010. Dietary data obtained from children in 16 different countries were used to create a reference database for computing C-DII scores based on consumption of macronutrients, vitamins, minerals, and whole foods. Construct validation was performed using quantile regression to assess the association between C-reactive protein (CRP) concentrations and C-DII scores.

DATA SOURCES

All data used for construct validation were obtained from children between six and 14 years of age (n = 3300) who participated in the U.S. National Health and Nutrition Examination Survey (NHANES) (2005⁻2010).

RESULTS

The C-DII was successfully validated with blood CRP concentrations in this heterogeneous sample of 3300 children from NHANES (52% male; 29% African American, 25% Mexican American; mean age 11 years). The final model was adjusted for sex, age, race, asthma, body mass index (BMI), and infections. Children in level 3 (i.e., quartiles 3 and 4 combined) of the C-DII (i.e., children with the most pro-inflammatory diets) had a CRP value 0.097 mg/dL higher than that in level 1 (i.e., quartile 1) for CRP values at the 75th percentile of CRP using quantile regression (p < 0.05).

CONCLUSION

The C-DII predicted blood CRP concentrations among children 6⁻14 years in the NHANES. Further construct validation with CRP and other inflammatory markers is required to deepen understanding of the relationship between the C-DII and markers of inflammation in children.

Scutellarin Enhances Antitumor Effects and Attenuates the Toxicity of Bleomycin in H22 Ascites Tumor-Bearing Mice

Bleomycin (BLM) is a broad spectrum anti-tumor drug and inducing pulmonary fibrosis. As an anti-tumor drug without immunosuppression, it is urgent to find a drug that reduces the side effects of BLM. Scutellarin (SCU), a flavone extracted from Erigeron breviscapus (Vant.) Hand-Mazz, has anti-inflammatory activity and ability to inhibit tumor cell growth, migration, and invasion. However, the combined role of SCU and BLM treatment in tumor is unclear. This study aimed to investigate the possible effect and related mechanisms of BLM combined with SCU in the treatment of tumor through in vivo and in vitro experiments. In vivo experiments showed that BLM combined with SCU in the treatment of mice bearing H22 ascites tumor prolonged the survival time, alleviated BLM-induced pulmonary fibrosis, reduced the production of TNF-α; IL-6, and the levels of MDA and MPO. BLM combined with SCU increased the apoptotic rate of H22 ascites cells and the levels of cleaved-caspases-3 and -8. Furthermore, BLM combined with SCU increased the protein expression of p53 and gene expression of miR-29b, and decreased the expression of TGF-β1. In vitro experiment results showed that BLM combined with SCU inhibited the viability of H22 cells and MRC-5 cells, promoted H22 cell apoptosis, up-regulated the protein expression of p53 and down-regulated the protein expression of α-SMA and collagen-I in MRC-5 cells. These experimental results suggested that SCU could enhance the anti-tumor effect of BLM and reduce BLM-induced pulmonary fibrosis, indicating SCU as a potential adjuvant for BLM in the future.

miR-34a-mediated regulation of XIST in female cells under inflammation

Background

Evidence is overwhelming for sex differences in pain, with women representing the majority of the chronic pain patient population. There is a need to explore novel avenues to elucidate this sex bias in the development of chronic inflammatory pain conditions. Complex regional pain syndrome (CRPS) is a chronic neuropathic pain disorder, and the incidence of CRPS is greater in women than in men by ~4:1. Since neurogenic inflammation is a key feature of CRPS, dysregulation of inflammatory responses can be a factor in predisposing women to chronic pain.

Methods

Our studies investigating alterations in circulating microRNAs (miRNAs) in whole blood from female CRPS patients showed significant differential expression of miRNAs between responders and poor responders to ketamine treatment. Several of these miRNAs are predicted to target the long noncoding RNA, X-inactive-specific transcript (XIST). XIST mediates X-chromosome inactivation and is essential for equalizing the expression of X-linked genes between females and males. Based on the well-established role in inflammatory process, we focused on miR-34a, one of the miRNAs predicted to target XIST, and downregulated in CRPS patients responding poorly to ketamine.

Results

Our in vitro and in vivo models of acute inflammation and data from patients with CRPS showed that miR-34a can regulate XIST under inflammation directly, and through pro-inflammatory transcription factor Yin-Yang 1 (YY1). XIST was significantly upregulated in a subset of CRPS patients responding poorly to ketamine.

Conclusion

Since dysregulation of XIST can result in genes escaping inactivation or reactivation in female cells, further investigations on the role of XIST in the predominance of chronic inflammatory and pain disorders in women is warranted.

Identification of Exosomal miRNAs in Rats With Pulmonary Neutrophilic Inflammation Induced by Zinc Oxide Nanoparticles

It has been previously shown that inhaled zinc oxide nanoparticles (ZnO-NPs) can modulate inflammation. MicroRNAs (miRNAs) enclosed in exosomes have been identified as an important signature for inflammatory responses. However, the role of exosomal miRNAs during pathogenic inflammation has not been investigated. Healthy rats were exposed to ZnO-NPs (41.7 nm; 2, 4, and 8 mg/kg) or saline (control) via oropharyngeal aspiration. ZnO-NPs induced significant increases in the serum levels of interleukin 8 (IL-8), interleukin-1 beta (IL-1β), and tumor necrosis factor α (TNF-α), and elevated the number of cells and the percentage of neutrophils in the blood. Moreover, exposure to ZnO-NPs increased the levels of lactate dehydrogenase (LDH) activity and total protein in bronchoalveolar lavage fluid (BALF). Differential profiling of miRNAs in isolated serum exosomes revealed that 16 miRNAs were up-regulated and 7 down-regulated in ZnO-NP-treated rats compared with the controls. Functional and pathway analysis indicated that miRNAs may participate in inflammation directly and indirectly through protein and vesicle-mediated transport or regulation of IL-1, oxidative stress, apoptosis, and autophagy. These results suggest that miRNAs in serum exosomes are involved in pulmonary neutrophilic inflammation induced by ZnO-NPs.

Alternative mechanisms of miR-34a regulation in cancer

MicroRNA miR-34a is recognized as a master regulator of tumor suppression. The strategy of miR-34a replacement has been investigated in clinical trials as the first attempt of miRNA application in cancer treatment. However, emerging outcomes promote the re-evaluation of existing knowledge and urge the need for better understanding the complex biological role of miR-34a. The targets of miR-34a encompass numerous regulators of cancer cell proliferation, survival and resistance to therapy. MiR-34a expression is transcriptionally controlled by p53, a crucial tumor suppressor pathway, often disrupted in cancer. Moreover, miR-34a abundance is fine-tuned by context-dependent feedback loops. The function and effects of exogenously delivered or re-expressed miR-34a on the background of defective p53 therefore remain prominent issues in miR-34a based therapy. In this work, we review p53-independent mechanisms regulating the expression of miR-34a. Aside from molecules directly interacting with MIR34A promoter, processes affecting epigenetic regulation and miRNA maturation are discussed. Multiple mechanisms operate in the context of cancer-associated phenomena, such as aberrant oncogene signaling, EMT or inflammation. Since p53-dependent tumor-suppressive mechanisms are disturbed in a substantial proportion of malignancies, we summarize the effects of miR-34a modulation in cell and animal models in the clinically relevant context of disrupted or insufficient p53 function.

MicroRNA-181 Variants Regulate T Cell Phenotype in the Context of Autoimmune Neuroinflammation

Background

Recent studies have revealed that multiple sclerosis (MS) lesions have distinct microRNA (miRNA) expression profiles. miR-181 family members show altered expression in MS tissues although their participation in MS pathogenesis remains uncertain. Herein, we investigated the involvement of miR-181a and miR-181b in the pathogenesis of MS and its animal model, experimental autoimmune encephalomyelitis (EAE).

Methods

miR-181a and -b levels were measured in the central nervous system (CNS) of patients with MS and mice with EAE as well as relevant leukocyte cultures by real-time RT-PCR. To examine the role of the miRNAs in leukocyte differentiation and function, miR-181a and -b mimic sequences were transfected into cultured primary macrophages and purified CD4⁺ T cells which were then analyzed by RT-PCR and flow cytometry. Luciferase reporter assays were performed to investigate the interaction of miR-181a and -b with the 3′-UTR of potential target transcripts, and the expression of target genes was measured in the CNS of EAE mice, activated lymphocytes, and macrophages.

Results

Expression analyses revealed a significant decrease in miR-181a and -b levels in brain white matter from MS patients as well as in spinal cords of EAE mice during the acute and chronic phases of disease. Suppression of miR-181a was observed following antigen-specific or polyclonal activation of lymphocytes as well as in macrophages following LPS treatment. Overexpression of miR-181a and -b mimic sequences reduced proinflammatory gene expression in macrophages and polarization toward M1 phenotype. miR-181a and -b mimic sequences inhibited Th1 generation in CD4⁺ T cells and miR-181a mimic sequences also promoted Treg differentiation. Luciferase assays revealed Suppressor of mothers against decapentaplegic 7 (Smad7), as a direct target of miR-181a and -b.

Conclusion

Our data highlight the anti-inflammatory actions of miR-181a and -b in the context of autoimmune neuroinflammation. miR-181a and -b influence differentiation of T helper cell and activation of macrophages, providing potential therapeutic options for controlling inflammation in MS.

NO• and Pancreatic Cancer: A Complex Interaction with Therapeutic Potential

SIGNIFICANCE

Pancreatic tumors express high level of nitric oxide synthases (NOSs) in particular inducible (iNOS/NOS2) and endothelial (eNOS/NOS3) forms. However, the role of nitric oxide (NO^•) in the development and progression of pancreatic cancer is not clearly defined. Delineating the NO^•-induced signaling in pancreatic cancer and its potential contribution in disease aggressiveness may provide therapeutic targets to improve survival in this lethal malignancy. Recent Advances: An increased expression of NOS2/iNOS in tumors is associated with poorer survival in early stage resected patients with pancreatic ductal adenocarcinoma (PDAC). Furthermore, genetic deletion of NOS2 enhanced survival in mice with autochthonous PDAC. Additionally, targeting NOS3/eNOS reduced the abundance of precursor lesions in mice, which trended toward improved survival.

CRITICAL ISSUES

The extremely poor prognosis in pancreatic cancer is due to the late diagnosis and lack of effective therapy in advanced disease. One of the most critical issues is to decipher the underlying mechanism of disease aggressiveness and therapeutic resistance for identifying potential therapeutic target and effective treatment. Given the evidence of a strong association between inflammation and pancreatic cancer and clinical evidence, which suggests an association between NOS2 and disease aggressiveness, it is critical to define the role of NO^• signaling in this lethal malignancy.

FUTURE DIRECTIONS

Recent preclinical and clinical evidences indicate a potential therapeutic significance of targeting NO^• signaling in pancreatic cancer. With the emergence of new preclinical models, including the patient-derived organoids, further preclinical evaluation using clinically tested NOS inhibitors is needed for designing future clinical investigation. Antioxid. Redox Signal. 26, 1000-1008.

Supercritical-Carbon Dioxide Fluid Extract from Chrysanthemum indicum Enhances Anti-Tumor Effect and Reduces Toxicity of Bleomycin in Tumor-Bearing Mice

Bleomycin (BLM), a family of anti-tumor drugs, was reported to exhibit severe side effects limiting its usage in clinical treatment. Therefore, finding adjuvants that enhance the anti-tumor effect and reduce the detrimental effect of BLM is a prerequisite. Chrysanthemum indicum, an edible flower, possesses abundant bioactivities; the supercritical-carbon dioxide fluid extract from flowers and buds of C. indicum (CI_SCFE) have strong anti-inflammatory, anti-oxidant, and lung protective effects. However, the role of CI_SCFE combined with BLM treatment on tumor-bearing mice remains unclear. The present study aimed to investigate the potential synergistic effect and the underlying mechanism of CI_SCFE combined with BLM in the treatment of hepatoma 22 (H22) tumor-bearing mice. The results suggested that the oral administration of CI_SCFE combined with BLM could markedly prolong the life span, attenuate the BLM-induced pulmonary fibrosis, suppress the production of pro-inflammatory cytokines (interleukin-6), tumor necrosis factor-α, activities of myeloperoxidase, and malondiadehyde. Moreover, CI_SCFE combined with BLM promoted the ascites cell apoptosis, the activities of caspases 3 and 8, and up-regulated the protein expression of p53 and down-regulated the transforming growth factor-β1 by activating the gene expression of miR-29b. Taken together, these results indicated that CI_SCFE could enhance the anti-cancer activity of BLM and reduce the BLM-induced pulmonary injury in H22 tumor-bearing mice, rendering it as a potential adjuvant drug with chemotherapy after further investigation in the future.

MicroRNA-29a/b/c targets iNOS and is involved in protective remote ischemic preconditioning in an ischemia-reperfusion rat model of non-alcoholic fatty liver disease

Remote ischemic preconditioning (RIPC) protects against the injury that is incurred by ischemia and reperfusion (IR); however, the role of RIPC in liver IR injury in non-alcoholic fatty liver disease (NAFLD) remains unclear. In this study, a NAFLD rat model was utilized in a series of different surgical procedures and molecular experiments. Rats of the IR group and the RIPC+IR group exhibited more severe injury than NAFLD control rats (in which the liver was prodded following a median-incision laparotomy). The liver condition, measured by serum alanine transaminase and aspartate transaminase levels, of the RIPC+IR group was better than that of the IR group. In addition, alanine transaminase and aspartate transaminase levels were lower in the RIPC+IR group compared with the IR group (P<0.001). Flow cytometry revealed that the cell apoptosis ratio was significantly lower in the RIPC+IR group than in the IR group (P<0.001). Reverse transcription-polymerase chain reaction (RT-qPCR) was used to assess miR-29a/b/c levels, revealing that they were significantly reduced in the RIPC and RIPC+IR groups, but did not vary in the IR group compared with the control group. RT-qPCR also revealed that iNOS mRNA levels were not significantly different among any of the NAFLD groups; however, western blot analysis indicated that iNOS protein levels were increased in the RIPC group and the RIPC+IR group compared with the control and IR groups. A luciferase reporter assay demonstrated that transfection with miR-29a/b/c mimics significantly decreased the luciferase activities of plasmids containing the wild-type iNOS 3'-untranslated region (UTR) (relative fluorescence intensity: 0.47±0.06 for miR-29a, 0.36±0.07 for miR-29b, 0.41±0.04 for miR-29c; P<0.001), whereas the activities of plasmids containing the mutant iNOS 3'-UTR sequence were not markedly affected [relative fluorescence intensity: 0.99±0.08 for miR-29a (P=0.1349), 0.99±0.09 for miR-29b (P=0.1607), 0.97±0.07 for miR-29c (P=0.1824)]. This suggested that miR-29a/b/c downregulates iNOS by directly targeting its 3'-UTR. In summary, the results suggest that RIPC has a protective effect in NAFLD liver IR injury, which may be due to reduced miR-29a/b/c levels in the skeletal muscle, leading to increased iNOS and, therefore, nitric oxide.

MicroRNAs and Inflammation in Colorectal Cancer

Colorectal cancers (CRC) are known to be related to inflammatory conditions, and inflammatory bowel diseases increase the relative risk for developing CRC. The use of anti-inflammatory drugs prevents the development of colorectal cancer.Several molecular mediators are connecting the pathways that are involved in inflammatory conditions and in carcinogenesis. By the way these pathways are tightly interwoven, with the consequence that a deregulation at the level of any of these molecular mediators can affect the others.MiRNAs are demonstrated to be deregulated in inflammatory bowel diseases and in colorectal cancer. Moreover, they target several molecular mediators that connect inflammation to cancer, and they are thus implicated in the route from inflammation to colorectal cancer.This chapter will focus on the miRNAs that are jointly deregulated in inflammatory bowel disease and in colorectal cancer. Their role on the regulation of the molecular mediators and pathways that link inflammation to cancer will be described.

P53-dependent miRNAs mediate nitric oxide-induced apoptosis in colonic carcinogenesis

Both miRNAs and nitric oxide (NO) play important roles in colonic inflammation and tumorigenesis. Resistance of colonic epithelial cells to apoptosis may contribute to tumor development. We hypothesized that some miRNAs could increase the resistance of colonic cancer cells to nitric oxide-induced apoptotic cell death. Here we show that NO induced apoptosis and stimulated expression of some miRNAs. Loss of p53 not only blocked NO-induced apoptosis but also dramatically inhibited the expression of NO-related miRNAs, such as miR-34, miR-203, and miR-1301. In addition, blockage of p53-dependent miRNAs significantly reduced NO-induced apoptosis. Furthermore, forced expression of these miRNAs rendered HT-29 cells, which are resistant to apoptosis with mutant p53, more sensitive to NO-induced apoptotic cell death. Most interestingly, in a colitis-associated colon cancer mouse model, the level of miRNAs dropped significantly, accompanied by downregulation of p21, which is a key target gene of p53. In human colorectal cancer samples, the expression of miR-34 significantly correlated with the level of inducible nitric oxide synthase (iNOS). We contend that increased NO production may select cells with low levels of p53-dependent miRNAs which contributes to human colonic carcinogenesis and tumor progression.

Antioxidant Mechanisms and ROS-Related MicroRNAs in Cancer Stem Cells

Increasing evidence indicates that most of the tumors are sustained by a distinct population of cancer stem cells (CSCs), which are responsible for growth, metastasis, invasion, and recurrence. CSCs are typically characterized by self-renewal, the key biological process allowing continuous tumor proliferation, as well as by differentiation potential, which leads to the formation of the bulk of the tumor mass. CSCs have several advantages over the differentiated cancer cell populations, including the resistance to radio- and chemotherapy, and their gene-expression programs have been shown to correlate with poor clinical outcome, further supporting the relevance of stemness properties in cancer. The observation that CSCs possess enhanced mechanisms of protection from reactive oxygen species (ROS) induced stress and a different metabolism from the differentiated part of the tumor has paved the way to develop drugs targeting CSC specific signaling. In this review, we describe the role of ROS and of ROS-related microRNAs in the establishment and maintenance of self-renewal and differentiation capacities of CSCs.

Increased microRNA-34b and -34c predominantly expressed in stromal tissues is associated with poor prognosis in human colon cancer

The microRNA-34 family (miR-34a, -34b and -34c) have been reported to be tumor suppressor microRNAs (miRNAs) that are regulated by the TP53 and DNA hypermethylation. However, the expression, regulation, and prognostic value of the miR-34 family have not been systematically studied in colon cancer. To elucidate the roles of miR-34 family in colon carcinogenesis, miR-34a/b/c were measured in tumors and adjacent noncancerous tissues from 159 American and 113 Chinese colon cancer patients using quantitative RT-PCR, and we examined associations between miR-34a/b/c expression with TNM staging, cancer-specific mortality, TP53 mutation status and Affymetrix microarray data. All miR-34 family members were significantly increased in colon tumors, counter to the proposed tumor suppressor role for these miRNAs. Increased miR-34b/c were observed in more advanced tumors in two independent cohorts and increased expression of miR-34b/c was associated with poor cancer-specific mortality. While the expression of miR-34 family was not associated with TP53 mutation status, TP53 transcriptional activity was associated with miR-34a/b/c expression that is consistent with the proposed regulation of miR-34a/b/c by TP53. To examine where the miR-34 family is expressed, the expression of miR-34 family was compared between epitheliums and stromal tissues using laser microdissection technique. The expression of miR-34b/c was increased significantly in stromal tissues, especially in cancer stroma, compared with epithelial tissue. In conclusion, increased miR-34b/c predominantly expressed in stromal tissues is associated with poor prognosis in colon cancer. MiR-34 may contribute to cancer-stromal interaction associated with colon cancer progression.

Regulation of the extrinsic apoptotic pathway by microRNA-21 in alcoholic liver injury

IL-6/Stat3 is associated with the regulation of transcription of key cellular regulatory genes (microRNAs) during different types of liver injury. This study evaluated the role of IL-6/Stat3 in regulating miRNA and miR-21 in alcoholic liver disease. By microarray, we identified that ethanol feeding significantly up-regulated 0.8% of known microRNAs in mouse liver compared with controls, including miR-21. Similarly, the treatment of normal human hepatocytes (N-Heps) and hepatic stellate cells (HSCs) with ethanol and IL-6 significantly increased miR-21 expression. Overexpression of miR-21 decreased ethanol-induced apoptosis in both N-Heps and HSCs. The expression level of miR-21 was significantly increased after Stat3 activation in N-Heps and HSCs, in support of the concept that the 5'-promoter region of miR-21 is regulated by Stat3. Using real time PCR, we confirmed that miR-21 activation is associated with ethanol-linked Stat3 binding of the miR-21 promoter. A combination of bioinformatics, PCR array, dual-luciferase reporter assay, and Western blot analysis revealed that Fas ligand (TNF superfamily, member 6) (FASLG) and death receptor 5 (DR5) are the direct targets of miR-21. Furthermore, inhibition of miR-21 by specific Vivo-Morpholino and knock-out of IL-6 in ethanol-treated mice also increased the expression of DR5 and FASLG in vivo during alcoholic liver injury. The identification of miR-21 as an important regulator of hepatic cell survival, transformation, and remodeling in vitro, as well as its upstream modulators and downstream targets, will provide insight into the involvement of altered miRNA expression in contributing to alcoholic liver disease progression and testing novel therapeutic approaches for human alcoholic liver diseases.

Targeting CSCs in tumor microenvironment: the potential role of ROS-associated miRNAs in tumor aggressiveness

Reactive oxygen species (ROS) have been widely considered as critical cellular signaling molecules involving in various biological processes such as cell growth, differentiation, proliferation, apoptosis, and angiogenesis. The homeostasis of ROS is critical to maintain normal biological processes. Increased production of ROS, namely oxidative stress, due to either endogenous or exogenous sources causes irreversible damage of bio-molecules such as DNA, proteins, lipids, and sugars, leading to genomic instability, genetic mutation, and altered gene expression, eventually contributing to tumorigenesis. A great amount of experimental studies in vitro and in vivo have produced solid evidence supporting that oxidative stress is strongly associated with increased tumor cell growth, treatment resistance, and metastasis, and all of which contribute to tumor aggressiveness. More recently, the data have indicated that altered production of ROS is also associated with cancer stem cells (CSCs), epithelial-to-mesenchymal transition (EMT), and hypoxia, the most common features or phenomena in tumorigenesis and tumor progression. However, the exact mechanism by which ROS is involved in the regulation of CSC and EMT characteristics as well as hypoxia- and, especially, HIF-mediated pathways is not well known. Emerging evidence suggests the role of miRNAs in tumorigenesis and progression of human tumors. Recently, the data have indicated that altered productions of ROS are associated with deregulated expression of miRNAs, suggesting their potential roles in the regulation of ROS production. Therefore, targeting ROS mediated through the deregulation of miRNAs by novel approaches or by naturally occurring anti-oxidant agents such as genistein could provide a new therapeutic approach for the prevention and/or treatment of human malignancies. In this article, we will discuss the potential role of miRNAs in the regulation of ROS production during tumorigenesis. Finally, we will discuss the role of genistein, as a potent anti-tumor agent in the regulation of ROS production during tumorigenesis and tumor development.

Hsa-miR-34b/c rs4938723 T>C and hsa-miR-423 rs6505162 C>A polymorphisms are associated with the risk of esophageal cancer in a Chinese population

Esophageal cancer is the eighth most common cancer and sixth leading cause of cancer associated death worldwide. Besides environmental risk factors, genetic factors might play an important role in the esophageal cancer carcinogenesis. We conducted a hospital based case–control study to evaluate the genetic susceptibility of functional single nucleotide polymorphisms (SNPs) in the microRNAs on the development of esophageal cancer. A total of 629 esophageal squamous cell carcinoma (ESCC) cases and 686 controls were recruited for this study. The hsa-miR-34b/c rs4938723 T>C, pri-miR-124-1 rs531564 C>G, pre-miR-125a rs12975333 G>T and hsa-miR-423 rs6505162 C>A genotypes were determined using Ligation Detection Reaction (LDR) method. Our results demonstrated that hsa-miR-34b/c rs4938723 CC genotype had a decreased risk of ESCC. The association was evident among patients who never drinking. Hsa-miR-423 rs6505162 C>A might associated with a significantly increased risk of ESCC in patients who smoking. These findings indicated that functional polymorphisms hsa-miR-34b/c rs4938723 T>C and hsa-miR-423 rs6505162 C>A might alter individual susceptibility to ESCC. However, our results were obtained with a limited sample size. Future larger studies with other ethnic populations are required to confirm current findings.

NOD2-nitric oxide-responsive microRNA-146a activates Sonic hedgehog signaling to orchestrate inflammatory responses in murine model of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a debilitating chronic inflammatory disorder of the intestine. The interactions between enteric bacteria and genetic susceptibilities are major contributors of IBD etiology. Although genetic variants with loss or gain of NOD2 functions have been linked to IBD susceptibility, the mechanisms coordinating NOD2 downstream signaling, especially in macrophages, during IBD pathogenesis are not precisely identified. Here, studies utilizing the murine dextran sodium sulfate model of colitis revealed the crucial roles for inducible nitric-oxide synthase (iNOS) in regulating pathophysiology of IBDs. Importantly, stimulation of NOD2 failed to activate Sonic hedgehog (SHH) signaling in iNOS null macrophages, implicating NO mediated cross-talk between NOD2 and SHH signaling. NOD2 signaling up-regulated the expression of a NO-responsive microRNA, miR-146a, that targeted NUMB gene and alleviated the suppression of SHH signaling. In vivo and ex vivo studies confirmed the important roles for miR-146a in amplifying inflammatory responses. Collectively, we have identified new roles for miR-146a that established novel cross-talk between NOD2-SHH signaling during gut inflammation. Potential implications of these observations in therapeutics could increase the possibility of defining and developing better regimes to treat IBD pathophysiology.

MicroRNAs in pulmonary arterial remodeling

Pulmonary arterial remodeling is a presently irreversible pathologic hallmark of pulmonary arterial hypertension (PAH). This complex disease involves pathogenic dysregulation of all cell types within the small pulmonary arteries contributing to vascular remodeling leading to intimal lesions, resulting in elevated pulmonary vascular resistance and right heart dysfunction. Mutations within the bone morphogenetic protein receptor 2 gene, leading to dysregulated proliferation of pulmonary artery smooth muscle cells, have been identified as being responsible for heritable PAH. Indeed, the disease is characterized by excessive cellular proliferation and resistance to apoptosis of smooth muscle and endothelial cells. Significant gene dysregulation at the transcriptional and signaling level has been identified. MicroRNAs are small non-coding RNA molecules that negatively regulate gene expression and have the ability to target numerous genes, therefore potentially controlling a host of gene regulatory and signaling pathways. The major role of miRNAs in pulmonary arterial remodeling is still relatively unknown although research data is emerging apace. Modulation of miRNAs represents a possible therapeutic target for altering the remodeling phenotype in the pulmonary vasculature. This review will focus on the role of miRNAs in regulating smooth muscle and endothelial cell phenotypes and their influence on pulmonary remodeling in the setting of PAH.

High levels of oncomiR-21 contribute to the senescence-induced growth arrest in normal human cells and its knock-down increases the replicative lifespan

Cellular senescence of normal human cells has by now far exceeded its initial role as a model system for aging research. Many reports show the accumulation of senescent cells in vivo, their effect on their microenvironment and its double-edged role as tumour suppressor and promoter. Importantly, removal of senescent cells delays the onset of age-associated diseases in mouse model systems. To characterize the role of miRNAs in cellular senescence of endothelial cells, we performed miRNA arrays from HUVECs of five different donors. Twelve miRNAs, comprising hsa-miR-23a, hsa-miR-23b, hsa-miR-24, hsa-miR-27a, hsa-miR-29a, hsa-miR-31, hsa-miR-100, hsa-miR-193a, hsa-miR-221, hsa-miR-222 and hsa-let-7i are consistently up-regulated in replicatively senescent cells. Surprisingly, also miR-21 was found up-regulated by replicative and stress-induced senescence, despite being described as oncogenic. Transfection of early passage endothelial cells with miR-21 resulted in lower angiogenesis, and less cell proliferation mirrored by up-regulation of p21^CIP1 and down-regulation of CDK2. These two cell-cycle regulators are indirectly regulated by miR-21 via its validated direct targets NFIB (Nuclear factor 1 B-type), a transcriptional inhibitor of p21^CIP1, and CDC25A, which regulates CDK2 activity by dephosphorylation. Knock-down of either NFIB or CDC25A shows a phenocopy of over-expressing miR-21 in regard to cell-cycle arrest. Finally, miR-21 over-epxression reduces the replicative lifespan, while stable knock-down by sponges extends the replicative lifespan of endothelial cells. Therefore, we propose that miR-21 is the first miRNA that upon its knock-down extends the replicative lifespan of normal human cells.

Associations of pri-miR-34b/c and pre-miR-196a2 polymorphisms and their multiplicative interactions with hepatitis B virus mutations with hepatocellular carcinoma risk

Background

Genetic polymorphisms of pri-miR-34b/c and pre-miR-196a2 have been reported to be associated with the susceptibility to cancers. However, the effect of these polymorphisms and their interactions with hepatitis B virus (HBV) mutations on the development of hepatocellular carcinoma (HCC) remains largely unknown. We hypothesized that these polymorphisms might interact with the HBV mutations and play a role in hepatocarcinogenesis.

Methods

Pri-miR-34b/c rs4938723 (T>C) and pre-miR-196a2 rs11614913 (T>C) were genotyped in 3,325 subjects including 1,021 HBV-HCC patients using quantitative PCR. HBV mutations were determined by direct sequencing. Contributions of the polymorphisms and their multiplicative interactions with gender or HCC-related HBV mutations to HCC risk were assessed using multivariate regression analyses.

Results

rs4938723 CC genotype was significantly associated with HCC risk compared to HBV natural clearance subjects, adjusted for age and gender (adjusted odds ratio [AOR] = 2.01, 95% confidence interval [CI] = 1.16–3.49). rs4938723 variant genotypes in dominant model significantly increased HCC risk in women, compared to female healthy controls (AOR = 1.85, 95% CI = 1.20–2.84) or female HCC-free subjects (AOR = 1.62, 95% CI = 1.14–2.31). rs4938723 CC genotype and rs11614913 TC genotype were significantly associated with increased frequencies of the HCC-related HBV mutations T1674C/G and G1896A, respectively. rs11614913 was not significantly associated with HCC risk, but its CC genotype significantly enhanced the effect of rs4938723 in women. In multivariate regression analyses, rs4938723 in dominant model increased HCC risk (AOR = 1.62, 95% CI = 1.05–2.49), whereas its multiplicative interaction with C1730G, a HBV mutation inversely associated with HCC risk, reduced HCC risk (AOR = 0.34, 95% CI = 0.15–0.81); rs11614913 strengthened the G1896A effect but attenuated the A3120G/T effect on HCC risk.

Conclusions

rs4938723 might be a genetic risk factor of HCC but its effect on HCC is significantly affected by the HBV mutations. rs11614913 might not be a HCC susceptible factor but it might affect the effects of the HBV mutations or rs4938723 on HCC risk.

Potentially prognostic miRNAs in HPV-associated oropharyngeal carcinoma

PURPOSE

Deregulation of miRNAs is associated with almost all human malignancies. Human papillomavirus (HPV)-associated oropharyngeal carcinoma (OPC) has a significantly more favorable outcome compared with HPV-negative OPCs; however, the underlying mechanisms are not well understood. Hence, the objectives of this study were to determine whether miRNA expression differed as a function of HPV status and to assess whether such miRNAs provide prognostic value beyond HPV status.

METHODS

Global miRNA profilings were conducted on 88 formalin-fixed and paraffin-embedded (FFPE) OPC biopsies (p16-positive: 56; p16-negative: 32), wherein the expression levels of 365 miRNAs plus 3 endogenous controls were simultaneously measured using quantitative real-time (qRT)-PCR. Seven FFPE specimens of histologically normal tonsils were used as controls.

RESULTS

Overall, 224 miRNAs were expressed in more than 80% of the investigated samples, with 128 (57%) being significantly differentially expressed between tumor versus normal tissues (P < 0.05). Upregulated miR-20b, miR-9, and miR-9* were significantly associated with HPV/p16-status. Three miRNA sets were significantly associated with overall survival (miR-107, miR-151, miR-492; P = 0.0002), disease-free survival (miR-20b, miR-107, miR-151, miR-182, miR-361; P = 0.0001), and distant metastasis (miR-151, miR-152, miR-324-5p, miR-361, miR492; P = 0.0087), which retained significance even after adjusting for p16 status. The associated biologic functions of these miRNAs include immune surveillance, treatment resistance, invasion, and metastasis.

CONCLUSION

We have identified several miRNAs, which associate with HPV status in OPC; furthermore, three candidate prognostic sets of miRNAs seem to correlate with clinical outcome, independent of p16 status. Furthermore, evaluations will offer biologic insights into the mechanisms underlying the differences between HPV-positive versus HPV-negative OPC.

Bladder cancer: a simple model becomes complex

Bladder cancer is one of the most frequent malignancies in developed countries and it is also characterized by a high number of recurrences. Despite this, several authors in the past reported that only two altered molecular pathways may genetically explain all cases of bladder cancer: one involving the FGFR3 gene, and the other involving the TP53 gene. Mutations in any of these two genes are usually predictive of the malignancy final outcome. This cancer may also be further classified as low-grade tumors, which is always papillary and in most cases superficial, and high-grade tumors, not necessarily papillary and often invasive. This simple way of considering this pathology has strongly changed in the last few years, with the development of genome-wide studies on expression profiling and the discovery of small non-coding RNA affecting gene expression. An easy search in the OMIM (On-line Mendelian Inheritance in Man) database using "bladder cancer" as a query reveals that genes in some way connected to this pathology are approximately 150, and some authors report that altered gene expression (up- or down-regulation) in this disease may involve up to 500 coding sequences for low-grade tumors and up to 2300 for high-grade tumors. In many clinical cases, mutations inside the coding sequences of the above mentioned two genes were not found, but their expression changed; this indicates that also epigenetic modifications may play an important role in its development. Indeed, several reports were published about genome-wide methylation in these neoplastic tissues, and an increasing number of small non-coding RNA are either up- or down-regulated in bladder cancer, indicating that impaired gene expression may also pass through these metabolic pathways. Taken together, these data reveal that bladder cancer is far to be considered a simple model of malignancy. In the present review, we summarize recent progress in the genome-wide analysis of bladder cancer, and analyse non-genetic, genetic and epigenetic factors causing extensive gene mis-regulation in malignant cells.

NOS2 enhances KRAS-induced lung carcinogenesis, inflammation and microRNA-21 expression

Mutant KRAS in lung cancers induces molecular pathways that regulate cellular proliferation, survival and inflammation, which enhance tumorigenesis. Inducible nitric oxide synthase (NOS2) upregulation and sustained nitric oxide generation are induced during the inflammatory response and correlate positively with lung tumorigenesis. To explore the mechanistic contribution of NOS2 to KRAS-induced lung tumorigenesis and inflammation, we used a genetic strategy of crossing NOS2 knockout (NOS2KO) C57BL6 inbred mice with a KRAS(G12D)-driven mouse lung cancer model. KRAS(G12D);NOS2KO mice exhibited delayed lung tumorigenesis and a longer overall survival time compared to that of KRAS(G12D);NOS2WT (wild-type) controls. Correspondingly, tumors in KRAS(G12D);NOS2KO mice had reduced tumor cell proliferation in adenomas and carcinomas. NOS2 deficiency also led to markedly suppressed inflammatory response by attenuation of macrophage recruitment into alveoli and within tumor foci. In contrast, FOXP3+ regulatory T cells were increased in tumors from KRAS(G12D) ;NOS2KO mice. We further analyzed the expression of microRNA-21 (miR-21), an oncogenic noncoding RNA involved in oncogenic Ras signaling, by quantitative reverse-transcription polymerase chain reaction and in situ hybridization. Lung carcinomas dissected from KRAS(G12D);NOS2KO mice showed a significantly reduced miR-21 expression along with decreased tumor cell proliferation, suggesting that NOS2 deficiency could attenuate RAS signaling pathways that transactivate miR-21 expression. Therefore, deletion of NOS2 decreases lung tumor growth as well as inflammatory responses initiated by oncogenic KRAS, suggesting that both KRAS and NOS2 cooperate in driving lung tumorigenesis and inflammation. Inhibition of NOS2 may have a therapeutic value in lung cancers with oncogenic KRAS mutations.

Oxidative stress and cancer: an overview

Reactive species, which mainly include reactive oxygen species (ROS), are products generated as a consequence of metabolic reactions in the mitochondria of eukaryotic cells. In normal cells, low-level concentrations of these compounds are required for signal transduction before their elimination. However, cancer cells, which exhibit an accelerated metabolism, demand high ROS concentrations to maintain their high proliferation rate. Different ways of developing ROS resistance include the execution of alternative pathways, which can avoid large amounts of ROS accumulation without compromising the energy demand required by cancer cells. Examples of these processes include the guidance of the glycolytic pathway into the pentose phosphate pathway (PPP) and/or the generation of lactate instead of employing aerobic respiration in the mitochondria. Importantly, ROS levels can be used as a thermostat to monitor the damage that cells can bear. The implications for ROS regulation are highly significant for cancer therapy because commonly used radio- and chemotherapeutic drugs influence tumor outcome through ROS modulation. Moreover, the discovery of novel biomarkers that are able to predict the clinical response to pro-oxidant therapies is a crucial challenge to overcome to allow for the personalization of cancer therapies.

Macrophages, nitric oxide and microRNAs are associated with DNA damage response pathway and senescence in inflammatory bowel disease

BACKGROUND

Cellular senescence can be a functional barrier to carcinogenesis. We hypothesized that inflammation modulates carcinogenesis through senescence and DNA damage response (DDR). We examined the association between senescence and DDR with macrophage levels in inflammatory bowel disease (IBD). In vitro experiments tested the ability of macrophages to induce senescence in primary cells. Inflammation modulating microRNAs were identified in senescence colon tissue for further investigation.

METHODOLOGY/PRINCIPAL FINDINGS

Quantitative immunohistochemistry identified protein expression by colon cell type. Increased cellular senescence (HP1γ; P = 0.01) or DDR (γH2A.X; P = 0.031, phospho-Chk2, P = 0.014) was associated with high macrophage infiltration in UC. Co-culture with macrophages (ANA-1) induced senescence in >80% of primary cells (fibroblasts MRC5, WI38), illustrating that macrophages induce senescence. Interestingly, macrophage-induced senescence was partly dependent on nitric oxide synthase, and clinically relevant NO• levels alone induced senescence. NO• induced DDR in vitro, as detected by immunofluorescence. In contrast to UC, we noted in Crohn's disease (CD) that senescence (HP1γ; P<0.001) and DDR (γH2A.X; P<0.05, phospho-Chk2; P<0.001) were higher, and macrophages were not associated with senescence. We hypothesize that nitric oxide may modulate senescence in CD; epithelial cells of CD had higher levels of NOS2 expression than in UC (P = 0.001). Microarrays and quantitative-PCR identified miR-21 expression associated with macrophage infiltration and NOS2 expression.

CONCLUSIONS

Senescence was observed in IBD with senescence-associated β-galactosidase and HP1γ. Macrophages were associated with senescence and DDR in UC, and in vitro experiments with primary human cells showed that macrophages induce senescence, partly through NO•, and that NO• can induce DDR associated with senescence. Future experiments will investigate the role of NO• and miR-21 in senescence. This is the first study to implicate macrophages and nitrosative stress in a direct effect on senescence and DDR, which is relevant to many diseases of inflammation, cancer, and aging.

Interactions of miR-34b/c and TP53 polymorphisms on the risk of intracranial aneurysm

Several lines of evidence indicate that inflammatory processes play a key role in the happening and development of intracranial aneurysm (IA). Recently, polymorphisms in the TP53 gene were shown to be associated with inflammation and inflammatory disease. The aim of this study was to investigate the interactions of miR-34b/c and TP53 Arg72-Pro polymorphisms on the risk of IA in a Chinese population. A total of 590 individuals (including 164 patients with IA and 426 controls) were involved in this study. The polymorphisms (i.e., miR-34b/c rs4938723 and TP53 Arg72-Pro) were genotyped by polymerase chain reaction-restriction fragment length polymorphism assay and DNA sequencing. We found that the CC genotype of miR-34b/c rs4938723 was significantly associated with a decreased risk of IA compared with the TT genotype. Moreover, a significant gene interaction of the carriers with the combined genotypes of miR-34b/c rs4938723CC and TP53 Arg72Pro CG/CC/GG had a decreased risk of IA, compared with those carrying miR-34b/c rs4938723CT/TT+TP53 Arg72Pro GG/CG/CC combined genotypes. These findings suggest that the miR-34b/c rs4938723CC and TP53 Arg72-Pro polymorphisms may be involved in the susceptibility to IA.