microRNA alterations driving acute and late stages of radiation-induced fibrosis in a murine skin model

microRNA blood signature for localized radiation injury

A radiological accident, whether from industrial, medical, or malicious origin, may result in localized exposure to high doses of ionizing radiations, leading to the development of local radiation injury (LRI), that may evolve toward deep ulceration and necrosis of the skin and underlying tissues. Early diagnosis is therefore crucial to facilitate identification and management of LRI victims. Circulating microRNAs (miRNA) have been studied as potential diagnostic biomarkers of several diseases including hematological defects following whole-body irradiation (WBI). This study aims to identify a blood miRNA signature associated with LRI in a preclinical C57BL/6J mouse model of hindlimb irradiation using different 10-MV X-ray doses that lead to injuries of different severities. To this end, we first performed broad-spectrum plasma miRNA profiling, followed by a targeted validation step, on two independent animal cohorts. Using a multivariate sparse partial least square discriminant analysis, we identified a panel of eight circulating miRNAs able to segregate mice according to LRI severity. Interestingly, these miRNAs were previously associated with WBI (miR-150-5p, miR-342-3p, miR-146a-5p), inflammation (miR-18a-5p, miR-148b-3p, miR-532-5p) and skin diseases (miR-139-5p, miR-195-5p). Our results suggest the use of circulating miRNAs as suitable molecular biomarkers for LRI prognosis and diagnosis.

Radiation-induced circulating microRNAs linked to echocardiography parameters after radiotherapy

Introduction

Patients treated with radiotherapy to the chest region are at risk of cardiac sequelae, however, identification of those with greatest risk of complications remains difficult. Here, we sought to determine whether short-term changes in circulating miRNA expression are related to measures of cardiac dysfunction in follow-up.

Materials and methods

Two parallel patient cohorts were enrolled and followed up for 3 years after completion of RT to treat left-sided breast cancer. In the primary group (N=28) we used a a panel of 752 miRNAs to identify miRNAs associated with radiation and cardiac indices at follow up. In the second, independent cohort (N=56) we validated those candidate miRNAs with a targeted qPCR panel. In both cohorts. serum samples were collected before RT, 24h after the last dose and 1 month after RT; cardiac echocardiography was performed 2.5-3 year after RT.

Results

Seven miRNAs in the primary group showed marked changes in serum miRNAs immediately after RT compared to baseline and associations with cardiopulmonary dose-volume histogram metrics. Among those miRNAs: miR-15b-5p, miR-22-3p, miR-424-5p and miR-451a were confirmed to show significant decrease of expression 24 hours post-RT in the validation cohort. Moreover, miR-29c, miR-451 and miR-424 were correlated with the end-diastolic diameter of the left ventricle, which was also confirmed in multivariable analysis adjusting for RT-associated factors.

Conclusion

We identified a subset of circulating miRNAs predictive for cardiac function impairment in patients treated for left-sided breast cancer, although longer clinical observation could determine if these can be used to predict major clinical endpoints.

MicroRNA-34a: A Novel Therapeutic Target in Fibrosis

Fibrosis can occur in many organs, and severe cases leading to organ failure and death. No specific treatment for fibrosis so far. In recent years, microRNA-34a (miR-34a) has been found to play a role in fibrotic diseases. MiR-34a is involved in the apoptosis, autophagy and cellular senescence, also regulates TGF-β1/Smad signal pathway, and negatively regulates the expression of multiple target genes to affect the deposition of extracellular matrix and regulate the process of fibrosis. Some studies have explored the efficacy of miR-34a-targeted therapies for fibrotic diseases. Therefore, miR-34a has specific potential for the treatment of fibrosis. This article reviews the important roles of miR-34a in fibrosis and provides the possibility for miR-34a as a novel therapeutic target in fibrosis.

Exosome-mediated radiosensitizing effect on neighboring cancer cells via increase in intracellular levels of reactive oxygen species

The precise mechanism of intercellular communication between cancer cells following radiation exposure is unclear. Exosomes are membrane‑enclosed small vesicles comprising lipid bilayers and are mediators of intercellular communication that transport a variety of intracellular components, including microRNAs (miRNAs or miRs). The present study aimed to identify novel roles of exosomes released from irradiated cells to neighboring cancer cells. In order to confirm the presence of exosomes in the human pancreatic cancer cell line MIAPaCa‑2, ultracentrifugation was performed followed by transmission electron microscopy and nanoparticle tracking analysis (NanoSight) using the exosome‑specific surface markers CD9 and CD63. Subsequent endocytosis of exosomes was confirmed by fluorescent microscopy. Cell survival following irradiation and the addition of exosomes was evaluated by colony forming assay. Expression levels of miRNAs in exosomes were then quantified by microarray analysis, while protein expression levels of Cu/Zn‑ and Mn‑superoxide dismutase (SOD1 and 2, respectively) enzymes in MIAPaCa‑2 cells were evaluated by western blotting. Results showed that the uptake of irradiated exosomes was significantly higher than that of non‑irradiated exosomes. Notably, irradiated exosomes induced higher intracellular levels of reactive oxygen species (ROS) and a higher frequency of DNA damage in MIAPaCa‑2 cells, as determined by fluorescent microscopy and immunocytochemistry, respectively. Moreover, six up‑ and five downregulated miRNAs were identified in 5 and 8 Gy‑irradiated cells using miRNA microarray analyses. Further analysis using miRNA mimics and reverse transcription‑quantitative PCR identified miR‑6823‑5p as a potential candidate to inhibit SOD1, leading to increased intracellular ROS levels and DNA damage. To the best of our knowledge, the present study is the first to demonstrate that irradiated exosomes enhance the radiation effect via increasing intracellular ROS levels in cancer cells. This contributes to improved understanding of the bystander effect of neighboring cancer cells.

Interferon-α inducible protein 6 (IFI6) confers protection against ionizing radiation in skin cells

BACKGROUND

Radiation-induced skin injury is one of the main adverse effects and a dose-limiting factor of radiotherapy without feasible treatment. The underlying mechanism of this disease is still limited.

OBJECTIVE

To investigate the potential molecular pathways and mechanisms of radiation-induced skin injury.

METHODS

mRNA expression profiles were determined by Affymetrix Human HTA2.0 microarray.IFI6 overexpression and knockdown were mediated by lentivirus. The functional changes of skin cells were measured by flow cytometry, ROS probe and Edu probe. Protein distribution was detected by immunofluorescence experiment, and IFI6-interacting proteins were detected by immunoprecipitation (IP) combined with mass spectrometry. The global gene changes in IFI6-overexpressed skin cells after irradiation were detected by RNA-seq.

RESULTS

mRNA expression profiling showed 50 upregulated and 13 down regulated genes and interferon alpha inducible protein 6 (IFI6) was top upregulated. Overexpression of IFI6 promoted cell proliferation and reduced cell apoptosis as well as ROS production following radiation, and conversely, increased the radiosensitivity of HaCaT and human skin fibroblast (WS1). IFI6 was translocated into nucleus in irradiated skin cells and the interacting relationship with mitochondrial single-stranded DNA-binding protein 1 (SSBP1), which could enhance the transcriptional activity of heat shock transcription factor 1 (HSF1).IFI6 augmented HSF1 activity following radiation in HaCaT and WS1 cells. RNA-seq analysis showed IFI6 modulated virus infection and cellular response to stress pathways, which may help to further explore how IFI6 regulate the transcriptional activity of HSF1.

CONCLUSION

This study reveals that IFI6 is induced by ionizing radiation and confers radioprotection in skin cells.

MicroRNAs and Long Non-coding RNAs in c-Met-Regulated Cancers

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are components of many signaling pathways associated with tumor aggressiveness and cancer metastasis. Some lncRNAs are classified as competitive endogenous RNAs (ceRNAs) that bind to specific miRNAs to prevent interaction with target mRNAs. Studies have shown that the hepatocyte growth factor/mesenchymal-epithelial transition factor (HGF/c-Met) pathway is involved in physiological and pathological processes such as cell growth, angiogenesis, and embryogenesis. Overexpression of c-Met can lead to sustained activation of downstream signals, resulting in carcinogenesis, metastasis, and resistance to targeted therapies. In this review, we evaluated the effects of anti-oncogenic and oncogenic non-coding RNAs (ncRNAs) on c-Met, and the interactions among lncRNAs, miRNAs, and c-Met in cancer using clinical and tissue chromatin immunoprecipition (ChIP) analysis data. We summarized current knowledge of the mechanisms and effects of the lncRNAs/miR-34a/c-Met axis in various tumor types, and evaluated the potential therapeutic value of lncRNAs and/or miRNAs targeted to c-Met on drug-resistance. Furthermore, we discussed the functions of lncRNAs and miRNAs in c-Met-related carcinogenesis and potential therapeutic strategies.

Creating a Favorable Microenvironment for Fat Grafting in a Novel Model of Radiation-Induced Mammary Fat Pad Fibrosis

BACKGROUND

Radiofibrosis of breast tissue compromises breast reconstruction by interfering with tissue viability and healing. Autologous fat transfer may reduce radiotherapy-related tissue injury, but graft survival is compromised by the fibrotic microenvironment. Elevated expression of receptor for hyaluronan-mediated motility (RHAMM; also known as hyaluronan-mediated motility receptor, or HMMR) in wounds decreases adipogenesis and increases fibrosis. The authors therefore developed RHAMM peptide mimetics to block RHAMM profibrotic signaling following radiation. They propose that this blocking peptide will decrease radiofibrosis and establish a microenvironment favoring adipose-derived stem cell survival using a rat mammary fat pad model.

METHODS

Rat mammary fat pads underwent a one-time radiation dose of 26 Gy. Irradiated (n = 10) and nonirradiated (n = 10) fat pads received a single intramammary injection of a sham injection or peptide NPI-110. Skin changes were examined clinically. Mammary fat pad tissue was processed for fibrotic and adipogenic markers using quantitative polymerase chain reaction and immunohistochemical analysis.

RESULTS

Clinical assessments and molecular analysis confirmed radiation-induced acute skin changes and radiation-induced fibrosis in rat mammary fat pads. Peptide treatment reduced fibrosis, as detected by polarized microscopy of picrosirius red staining, increased collagen ratio of 3:1, reduced expression of collagen-1 crosslinking enzymes lysyl-oxidase, transglutaminase 2, and transforming growth factor β1 protein, and increased adiponectin, an antifibrotic adipokine. RHAMM was expressed in stromal cell subsets and was downregulated by the RHAMM peptide mimetic.

CONCLUSION

Results from this study predict that blocking RHAMM function in stromal cell subsets can provide a postradiotherapy microenvironment more suitable for fat grafting and breast reconstruction.

LncRNA WWC2-AS1 functions AS a novel competing endogenous RNA in the regulation of FGF2 expression by sponging miR-16 in radiation-induced intestinal fibrosis

BACKGROUND

Recently, long non-coding RNAs (lncRNAs) were considered as important gene expression regulators involving various biological processes. In this study, we explored the role of lncRNAs in the pathogenesis of radiation-induced intestinal fibrosis (RIF).

METHODS

LncRNAs were screened by microarray (Human LncRNA Array v3.0, Arraystar, Inc.) and the differentially expressed lncRNAs in RIF and non-RIF were analyzed by bioinformatics methods. The expression of WWC2-AS1/miR-16/FGF2 axis was compared on mRNA and protein level between human intestinal CCD-18Co fibroblasts cell lines and subepithelial SEMFs in response to radiation treatment. The significance of WWC2-AS1 in regulating FGF2 associated proliferation, migration, invasion and fibrosis of CCD-18Co and SEMFs by exposure to radiation was analyzed by shRNA (WWC2-AS1 shRNA) knock-down of endogenous WWC2-AS1.

RESULTS

WWC2-AS1 and FGF2 level was significantly higher while miR-16 was down-regulated in radiation-treated intestinal tissues. WWC2-AS1 more potently boosted FGF2 expression via reducing miR-16, and WWC2-AS1 shRNA remarkably inhibited FGF2 associated proliferation, migration, invasion and fibrosis of radiation treatment in vitro, further demonstrating physical interaction between miR-16 and WWC2-AS1 in radiation-induced fibrosis progress.

CONCLUSIONS

WWC2-AS1 was highly expressed in RIF, may function as a ceRNA in the regulation of FGF2 by binding miR-16. Targeting WWC2-AS1 thus may benefit radiation-induced fibrosis treatment.

TGF-β1 Induces Epithelial-Mesenchymal Transition of Chronic Sinusitis with Nasal Polyps through MicroRNA-21

OBJECTIVES

To characterize the epithelial-mesenchymal transition (EMT) in chronic rhinosinusitis with nasal polyps (CRSwNP) and to investigate the mechanism by which microRNA-21 (miR-21) regulates EMT in CRSwNP.

METHOD

(1) Tissue experiments: Mucosa tissues were collected from 13 patients with CRSwNP and 12 patients with CRS without nasal polyps (CRSsNP), as well as 11 patients without CRS (controls). Protein localization and quantification were achieved by immunofluorescence staining and Western blotting, involving the epithelial marker protein E-cadherin and the mesenchymal marker proteins α-smooth muscle actin (α-SMA), fibronectin, and vimentin. Quantitative RT-PCR was used to detect the relative expression levels of miR-21 and TGF-β1 mRNAs. (2) Cellular experiments: Primary human nasal epithelial cells (PHNECs) treated with TGF-β1, or TGF-β1 with miR-21 inhibitor, or miR-21 mimics alone were observed for morphology changes under a phase-contrast microscope. The expression levels of epithelial/mesenchymal marker proteins were determined as aforementioned. PTEN and phosphorylated Akt were detected by Western blotting.

RESULTS

(1) Tissue experiments: Compared with the CRSsNP and control groups, the expression of E-cadherin was downregulated in the CRSwNP group, whereas the expression of TGF-β1, α-SMA, fibronectin, and vimentin was upregulated. The expression levels of miR-21 and TGF-β1 mRNAs in CRSwNP were significantly higher than those in CRSsNP and controls. (2) Cellular experiments: TGF-β1 induced EMT-like transformation in PHNECs, featured by changes in cell morphology and upregulation of mesenchymal proteins and miR-21. The miR-21 inhibitor, as well as the Akt-specific -inhibitor, suppressed TGF-β1-induced EMT. Mechanically, downregulation of miR-21 resulted in increased PTEN and decreased Akt phosphorylation. Furthermore, overexpression of miR-21 had the opposite effects.

CONCLUSIONS

Our findings suggest that the TGF-β1-miR-21-PTEN-Akt axis may contribute to the pathogenesis of CRSwNP. miR-21 might be a reliable target for treating nasal polyp genesis through EMT suppression. Moreover, miR-21 inhibitors could be a novel class of antipolyp drug that modulates PTEN expression and Akt activation. In addition, further investigation regarding the reason underlying miR-21 overexpression in CRSwNP could provide a molecular target for novel treatment strategies for nasal polyposis.

Reactive Oxygen Species Drive Epigenetic Changes in Radiation-Induced Fibrosis

Radiation-induced fibrosis (RIF) develops months to years after initial radiation exposure. RIF occurs when normal fibroblasts differentiate into myofibroblasts and lay down aberrant amounts of extracellular matrix proteins. One of the main drivers for developing RIF is reactive oxygen species (ROS) generated immediately after radiation exposure. Generation of ROS is known to induce epigenetic changes and cause differentiation of fibroblasts to myofibroblasts. Several antioxidant compounds have been shown to prevent radiation-induced epigenetic changes and the development of RIF. Therefore, reviewing the ROS-linked epigenetic changes in irradiated fibroblast cells is essential to understand the development and prevention of RIF.

Regulation of Cellular Senescence by miR-34a in Alcoholic Liver Injury

Alcoholic liver disease remains a major cause of liver-related morbidity and mortality, which ranges from alcoholic steatohepatitis to fibrosis/cirrhosis and hepatocellular carcinoma, and the related mechanisms are understood poorly. In this study, we aimed to investigate the role of miR-34a in alcohol-induced cellular senescence and liver fibrosis. We found that hepatic miR-34a expression was upregulated in ethanol-fed mice and heavy drinkers with steatohepatitis compared with respective controls. Mice treated with miR-34a Vivo-Morpholino developed less severe liver fibrosis than wild-type mice after 5 weeks of ethanol feeding. Further mechanism exploration showed that inhibition of miR-34a increased cellular senescence of hepatic stellate cells (HSCs) in ethanol-fed mice, although it decreased senescence in total liver and hepatocytes, which was verified by the changes of senescence-associated β-galactosidase and gene expression. Furthermore, enhanced cellular senescence was observed in liver tissues from steatohepatitis patients compared with healthy controls. In addition, the expression of transforming growth factor-β1, drosophila mothers against decapentaplegic protein 2 (Smad2), and Smad3 was decreased after inhibition of miR-34a in ethanol-fed mice. Our in vitro experiments showed that silencing of miR-34a partially blocked activation of HSCs by lipopolysaccharide and enhanced senescence of HSCs. Furthermore, inhibition of miR-34a decreased lipopolysaccharide-induced fibrotic gene expression in cultured hepatocytes. In conclusion, our data suggest that miR-34a functions as a profibrotic factor that promotes alcohol-induced liver fibrosis by reducing HSC senescence and increasing the senescence of hepatocytes.

Radiation-Induced Fibrosis: Mechanisms and Opportunities to Mitigate. Report of an NCI Workshop, September 19, 2016

A workshop entitled "Radiation-Induced Fibrosis: Mechanisms and Opportunities to Mitigate" (held in Rockville, MD, September 19, 2016) was organized by the Radiation Research Program and Radiation Oncology Branch of the Center for Cancer Research (CCR) of the National Cancer Institute (NCI), to identify critical research areas and directions that will advance the understanding of radiation-induced fibrosis (RIF) and accelerate the development of strategies to mitigate or treat it. Experts in radiation biology, radiation oncology and related fields met to identify and prioritize the key areas for future research and clinical translation. The consensus was that several known and newly identified targets can prevent or mitigate RIF in pre-clinical models. Further, basic and translational research and focused clinical trials are needed to identify optimal agents and strategies for therapeutic use. It was felt that optimally designed preclinical models are needed to better study biomarkers that predict for development of RIF, as well as to understand when effective therapies need to be initiated in relationship to manifestation of injury. Integrating appropriate endpoints and defining efficacy in clinical trials testing treatment of RIF were felt to be critical to demonstrating efficacy. The objective of this meeting report is to (a) highlight the significance of RIF in a global context, (b) summarize recent advances in our understanding of mechanisms of RIF,

MicroRNA expression signature and the therapeutic effect of the microRNA‑21 antagomir in hypertrophic scarring

Hypertrophic scars (HS) area fibroproliferative disorder of the skin, which causes aesthetic and functional impairment. However, the molecular pathogenesis of this disease remains largely unknown and currently no efficient treatment exists. MicroRNAs (miRNAs) are involved in a variety of pathophysiological processes, however the role of miRNAs in HS development remains unclear. To investigate the miRNA expression signature of HS, microarray analysis was performed and 152 miRNAs were observed to be differentially expressed in HS tissue compared with normal skin tissues. Of the miRNAs identified, miRNA‑21 (miR‑21) was significantly increased in HS tissues and hypertrophic scar fibroblasts (HSFBs) as determined by reverse transcription‑quantitative polymerase chain reaction analysis. It was also observed that, when miR‑21 in HSFBs was blocked through use of an antagomir, the phenotype of fibrotic fibroblasts in vitro was reversed, as demonstrated by growth inhibition, induction of apoptosis and suppressed expression of fibrosis‑associated genes collagen type I α 1 chain (COL1A1), COL1A2 and fibronectin. Furthermore, miR‑21 antagomir administration significantly reduced the severity of HS formation and decreased collagen deposition in a rabbit ear HS model. The total scar area and scar elevation index were calculated and were demonstrated to be significantly decreased in the treatment group compared with control rabbits. These results indicated that the miR‑21 antagomir has a therapeutic effect on HS and suggests that targeting miRNAs may be a successful and novel therapeutic strategy in the treatment of fibrotic diseases that are difficult to treat with existing methods.

Emergence of miR-34a in radiation therapy

Expressions of many microRNAs (miRNAs) in response to ionizing radiation (IR) have already been investigated and some of them seem to play an important role in the tumor radioresistance, normal tissue radiotoxicity or as predictive biomarkers to radiation. miR-34a is an emerging miRNA in recent radiobiology studies. Here, we review this miR-34 family member by detailing its different roles in radiation response and we will discuss about the role that it can play in radiation treatment. Thus, we will show that IR regulates miR-34a by increasing its expression. We will also highlight different biological processes involved in cellular response to IR and regulated by miR-34a in order to demonstrate the role it can play in tumor radio-response or normal tissue radiotoxicity as a radiosensitizer or radioprotector. miR-34a is poised to assert itself as an important player in radiobiology and should become more and more important in radiation therapy management.

Loss of miR-140 is a key risk factor for radiation-induced lung fibrosis through reprogramming fibroblasts and macrophages

Radiation-induced lung fibrosis (RILF) is a common side effect for patients with thoracic cancer receiving radiation therapy. RILF is characterized by excessive collagen deposition mediated by TGF-β1 and its downstream factor SMAD3, but the exact molecular mechanism leading to fibrosis is yet to be determined. The present study investigated the impact of miR-140 on RILF development. Herein, we first found that loss of miR-140 is a marker of fibrotic lung tissue in vivo one-year post-radiation treatment. We showed that miR-140 knockout primary lung fibroblasts have a higher percentage of myofibroblasts compared to wild type primary lung fibroblasts, and that loss of miR-140 expression leads to increased activation of TGF-β1 signaling as well as increased myofibroblast differentiation. We also identified fibronectin as a novel miR-140 target gene in lung fibroblasts. Finally, we have shown that miR-140 deficiency promotes accumulation of M2 macrophages in irradiated lung tissues. These data suggest that miR-140 is a key protective molecule against RILF through inhibiting myofibroblast differentiation and inflammation.

Radiogenomics: A systems biology approach to understanding genetic risk factors for radiotherapy toxicity?

Adverse reactions in normal tissue after radiotherapy (RT) limit the dose that can be given to tumour cells. Since 80% of individual variation in clinical response is estimated to be caused by patient-related factors, identifying these factors might allow prediction of patients with increased risk of developing severe reactions. While inactivation of cell renewal is considered a major cause of toxicity in early-reacting normal tissues, complex interactions involving multiple cell types, cytokines, and hypoxia seem important for late reactions. Here, we review 'omics' approaches such as screening of genetic polymorphisms or gene expression analysis, and assess the potential of epigenetic factors, posttranslational modification, signal transduction, and metabolism. Furthermore, functional assays have suggested possible associations with clinical risk of adverse reaction. Pathway analysis incorporating different 'omics' approaches may be more efficient in identifying critical pathways than pathway analysis based on single 'omics' data sets. Integrating these pathways with functional assays may be powerful in identifying multiple subgroups of RT patients characterised by different mechanisms. Thus 'omics' and functional approaches may synergise if they are integrated into radiogenomics 'systems biology' to facilitate the goal of individualised radiotherapy.

Regulatory roles of microRNA-21 in fibrosis through interaction with diverse pathways (Review)

MicroRNA-21 (miR-21) is a small, non-coding RNA which can regulate gene expression at the post‑transcriptional level. While the fibrogenic process is vital in tissue repair, proliferation and transition of fibrogenic cells combined with an imbalance of secretion and degradation of the extracellular matrix results in excessive tissue remodeling and fibrosis. Recent studies have indicated that miR‑21 is overexpressed during fibrosis and can regulate the fibrogenic process in a variety of organs and tissues via diverse pathways. The present review summarized the significant roles of miR-21 in fibrosis and discussed the underlying key pathways.

The Anti-fibrotic Effects and Mechanisms of MicroRNA-486-5p in Pulmonary Fibrosis

To identify microRNAs (miRNAs, miRs) with potential roles in lung fibrogenesis, we performed genome-wide profiling of miRNA expression in lung tissues from a silica-induced mouse model of pulmonary fibrosis using microarrays. Seventeen miRNAs were selected for validation via qRT-PCR based on the fold changes between the silica and the control group. The dysregulation of five miRNAs, including miR-21, miR-455, miR-151-3p, miR-486-5p and miR-3107, were confirmed by qRT-PCRs in silica-induced mouse model of pulmonary fibrosis and were also confirmed in a bleomycin (BLM)-induced mouse lung fibrosis. Notably, miR-486-5p levels were decreased in the serum samples of patients with silicosis, as well as in the lung tissues of patients with silicosis and idiopathic pulmonary fibrosis (IPF). In addition, as determined by luciferase assays and Western blotting, SMAD2, a crucial mediator of pulmonary fibrosis, was identified to be one of target genes of miR-486-5p. To test the potential therapeutic significance of this miRNA, we overexpressed miR-486-5p in animal models. At day 28, miR-486-5p expression significantly decreased both the distribution and severity of lung lesions compared with the silica group (P < 0.01). In addition, miR-486-5p had a similar effect in the BLM group (P < 0.001). These results indicate that miR-486-5p may inhibit fibrosis.

MicroRNA in radiotherapy: miRage or miRador?

At least half of all cancer patients will receive radiation therapy. Tumour radioresistance, or the failure to control certain tumours with this treatment, can result in locoregional recurrence; thus there is great interest in understanding the underlying biology and developing strategies to overcome this problem. The expanding investigation of microRNA in cancer suggests that these regulatory factors can influence the DNA damage response, the microenvironment and survival pathways, among other processes, and thereby may affect tumour radioresistance. As microRNA are readily detectable in tumours and biofluids, they hold promise as predictive biomarkers for therapy response and prognosis. This review highlights the current insights on the major ways that microRNA may contribute to tumour radiation response and whether their levels reflect treatment success. We conclude by applying the potential framework of future roles of miR in personalised radiotherapy using prostate cancer clinical management as an example.