Search

There is increasing evidence that the expression of non-coding RNA and mRNA (messenger RNA) is significantly altered following high-dose ionizing radiation (IR), and their expression may play a critical role in cellular responses to IR. However, the role of non-coding RNA and mRNA in radiation protection, especially in the nervous system, remains unknown. In this study, microarray profiles were used to determine microRNA (miRNA), long non-coding RNA (lncRNA), and mRNA expression in the hypothalamus of mice that were pretreated with amifostine and subsequently exposed to high-dose IR. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed. We found that fewer miRNAs, lncRNAs, and mRNAs were induced by amifostine pre-treatment in exposed mice, which exhibited antagonistic effects compared to IR, indicating that amifostine attenuated the IR-induced effects on RNA profiles. GO and KEGG pathway analyses showed changes in a variety of signaling pathways involved in inflammatory responses during radioprotection following amifostine pre-treatment in exposed mice. Taken together, our study revealed that amifostine treatment altered or attenuated miRNA, lncRNA, and mRNA expression in the hypothalamus of exposed mice. These data provide a resource to further elucidate the mechanisms underlying amifostine-mediated radioprotection in the hypothalamus.

Non-invasive far infrared radiation (FIR) has been observed to improve the health of patients with coronary artery disease (CAD). Endothelial colony forming cells (ECFCs) contribute to vascular repair and CAD. The goal of this study was to uncover the role of FIR in ECFCs function and to reveal potential biomarkers for indication of FIR therapy in CAD patients. FIR significantly enhanced in vitro migration (transwell assay) and tube formation (tube length) capacities in a subpopulation of CAD ECFCs. Clinical parameters associated with the responsiveness of ECFCs to FIR include smoking and gender. ECFCs from CAD patients that smoke did not respond to FIR in most cases. In contrast, ECFCs from females showed a higher responsiveness to FIR than ECFCs from males. To decipher the molecular mechanisms by which FIR modulates ECFCs functions, regardless of sex, RNA sequencing analysis was performed in both genders of FIR-responsive and FIR-non/unresponsive ECFCs. Gene Ontology (GO) analysis of FIR up-regulated genes indicated that the pathways enriched in FIR-responsive ECFCs were involved in cell viability, angiogenesis and transcription. Small RNA sequencing illustrated 18 and 14 miRNAs that are up- and down-regulated, respectively, in FIR-responsive CAD ECFCs in both genders. Among the top 5 up- and down-regulated miRNAs, down-regulation of miR-548aq-3p in CAD ECFCs after FIR treatment was observed in FIR-responsive CAD ECFCs by RT-qPCR. Down-regulation of miR-548aq-3p was correlated with the tube formation activity of CAD ECFCs enhanced by FIR. After establishment of the down-regulation of miR-548aq-3p by FIR in CAD ECFCs, we demonstrated through overexpression and knockdown experiments that miR-548aq-3p contributes to the inhibition of the tube formation of ECFCs. This study suggests the down-regulation of miR-548aq-3p by FIR may contribute to the improvement of ECFCs function, and represents a novel biomarker for therapeutic usage of FIR in CAD patients.

The shift of dark-grown seedlings into light causes enormous transcriptome changes followed by a dramatic developmental transition. Here, we show that microRNA (miRNA) biogenesis also undergoes regulatory changes during de-etiolation. Etiolated seedlings maintain low levels of primary miRNAs (pri-miRNAs) and miRNA processing core proteins, such as Dicer-like 1, SERRATE, and HYPONASTIC LEAVES 1, whereas during de-etiolation both pri-miRNAs and the processing components accumulate to high levels. However, the levels of most miRNAs do not notably increase in response to light. To reconcile this inconsistency, we demonstrated that an unknown suppressor decreases miRNA-processing activity and light-induced SMALL RNA DEGRADING NUCLEASE 1 shortens the half-life of several miRNAs in de-etiolated seedlings. Taken together, these data suggest a novel mechanism, miRNA-biogenetic inconsistency, which accounts for the intricacy of miRNA biogenesis during de-etiolation. This mechanism is essential for the survival of de-etiolated seedlings after long-term skotomorphogenesis and their optimal adaptation to ever-changing light conditions., (Copyright © 2019 The Author. Published by Elsevier Inc. All rights reserved.)

Electron beam (EB) irradiation is useful to reduce the recurrence of keloids; however, the underlying mechanism remains unknown. MicroRNA-21 (miR-21), which regulates autophagy during cancer radiation therapy, was identified as a potential therapeutic target for keloids. Here, we investigate the regulatory mechanism(s) of miR-21-5p on keloid fibroblast autophagy and migration after EB irradiation. The microRNA expression profile of the keloid dermis was examined by performing a microRNA microarray. Levels of LC3B and Beclin-1 were detected by immunohistochemical and western blot analysis in the keloid dermis and fibroblasts. Autophagy and apoptosis were tested in keloid fibroblasts after EB irradiation or transfection with an miR-21-5p inhibitor using electron microscopy, a Cyto-ID Green Autophagy Detection Kit, and an Annexin V PE Apoptosis Detection Kit. Migration was analyzed by an in vitro scratch-wound healing assay. Mechanistic tests were performed using small interfering RNAs to phosphatase and tensin homolog (siPTEN). Levels of miR-21-5p, PTEN, programmed cell death 4 (PDCD4), p-AKT, and apoptosis- and autophagy-associated genes were examined by qRT-PCR and western blotting. LC3B expression and migration ability were enhanced in fibroblasts and the keloid margin dermis compared with those in the adjacent normal skin. Both EB irradiation and an miR-21-5p inhibitor reduced keloid fibroblast autophagy, which was accompanied by decreased expression of miR-21-5p, p-AKT, and LC3B-II and increased expression of PTEN, PDCD4, and apoptosis-related genes. MiR-21-5p downregulation inhibited migration and suppressed LC3B expression and this was reversed by PTEN reduction. In conclusion, with increasing apoptosis, EB irradiation inhibits autophagy in keloid fibroblasts by reducing miR-21-5p, which regulates migration and LC3B expression via PTEN/AKT signaling. These data suggest a potential mechanism wherein miR-21-5p inhibition regulates autophagy and migration in EB-irradiated keloid fibroblasts, effectively preventing local invasion and recurrence. Therefore, miR-21-5p could be a new therapeutic target, to replace EB irradiation, and control keloid relapse.

Skin fibrosis is a chronic debilitating feature of several skin diseases that lead to characteristic increases in dermal fibroblast proliferation and collagen deposition through upregulation in components of the transforming growth factor beta (TGF-B)/SMAD pathway. In contrast to ultraviolet phototherapy, high-fluence light-emitting diode-generated red light (HF-LED-RL, 633 ± 15 nm) is a safe, economic and non-invasive therapy with in vitro evidence that supports modulation of the key cellular characteristics involved in the pathogenesis of skin fibrosis. Limited data exists pertaining to the effects of HF-LED-RL on human skin fibroblast microRNA (miRNA). Herein, we explored the effects of HF-LED-RL on fibroblast miRNA levels using RNA-seq and miRNA expression analysis. Using RNA-seq analysis we found that HF-LED-RL at 320 and 640 J/cm 2 increased transcription of key miRNA that are involved in skin fibrosis including miRNA-29, miRNA-196a and Let-7a, and decreased transcription of miRNA-21, miRNA-23b and miRNA-31. These microRNA findings provide insight into the molecular underpinnings of HF-LED-RL and highlight potential therapeutic targets of interest for the treatment of skin fibrosis. Additional research on the specific molecular mechanisms underlying HF-LED-RL effects on fibroblasts may provide further mechanistic insight into this therapy and may reveal additional future therapeutic targets for skin fibrosis., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

How melanocytes transform into melanoma cells remains largely unknown. However, prolonged ultraviolet radiation exposure is linked with melanoma, and the DNA of melanomas arising in chronically sun-exposed skin is characterized by an elevated number of pyrimidine transitions, mainly C>T (predominantly caused by ultraviolet B), and transversions of GC>TA or AT>CG (caused by ultraviolet A over indirect mechanisms). Since ultraviolet penetrates mostly only the superficial dermis, we sought to determine the extent to which superficial and deep melanocytes of nevi in sun-exposed skin differ in their miRNA expression and consider the changes as likely secondary to ultraviolet radiation-induced damage. The differentially expressed miRNAs were analyzed for known potential oncomiRs or linked to potential oncogenes or tumor suppressors. Superficial and deep melanocytes were microdissected from the nevi of 14 patients. The suspensions were processed for hybridization to a ribonucleotide protection system with 2280 total probes, including 2256 miRNA probes targeting 2083 human miRNAs. A comprehensive analysis of all human miRNAs registered in miRBase 11.0 was performed using the HTG Molecular Diagnostic database. Statistical analysis of these data yielded for 14 samples a statistically relevant profile of 39 miRNA species at FDR<0.1 that were differentially expressed between superficial and deep melanocytes. Ingenuity Pathway Analysis based on the expression data of these 39 miRNAs suggested the gene transcripts AR, MDM2, SMAD2/3, and YBX1 as the most probable miRNA targets, which were validated at the protein level. Our findings suggest that superficial ultraviolet radiation-damaged melanocytes can be differentiated from deep melanocytes on the basis of the expression of 39 miRNAs, the most probable gene transcript and protein targets of which are AR, MDM2, SMAD2/3, and YBX1, with YBX1 expression validating the best the molecular signature in immunohistochemical analysis.

Common complex diseases are a result of host and environment interactions. One such putative environmental factor is the electromagnetic field exposure, especially the occupational extremely low frequency (ELF) magnetic field, 50 Hz, 1 mT, whose neurobiological relevance remains elusive. We evaluated the effects of long-term (60 days) ELF-MF exposure on miRNAs previously related to brain and human diseases (miR-26b-5p, miR-9-5p, miR-29a-3p, miR-106b-5p, miR-107, miR-125a-3p). A total of 64 young (3 weeks-old) and mature (10 weeks-old) male/female Wistar-Albino rats were divided into sham and ELF-MF exposed groups. After sacrifice of the animals, blood samples from rat's tail vein and brain tissues were collected. The expression levels of miRNAs were investigated with Real-Time PCR technique and TaqMan probe Technology. All miRNA expression levels of the young female rats show a significant decrease in blood according to brain samples (p < 0.05), but fewer miRNAs displayed a similar significant decrease in the blood. In conclusion, these new observations might inform future clinical biological psychiatry studies of long-term electromagnetic field exposure, and the ways in which host-environment interactions contribute to brain diseases., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

It has historically been accepted that incorrectly repaired DNA double strand breaks (DSBs) are the principal lesions of importance regarding mutagenesis, and long-term biological effects associated with ionizing radiation. However, radiation may also cause dysregulation of epigenetic processes that can lead to altered gene function and malignant transformation, and epigenetic alterations are important causes of miRNAs dysregulation in cancer.Patched1 heterozygous (Ptch1+/-) mice, characterized by aberrant activation of the Sonic hedgehog (Shh) signaling pathway, are a well-known murine model of spontaneous and radiation-induced medulloblastoma (MB), a common pediatric brain tumor originating from neural granule cell progenitors (GCPs). The high sensitivity of neonatal Ptch1+/- mice to radiogenic MB is dependent on deregulation of the Ptch1 gene function. Ptch1 activates a growth and differentiation programme that is a strong candidate for regulation through the non-coding genome. Therefore we carried out miRNA next generation sequencing in ex vivo irradiated and control GCPs, isolated and purified from cerebella of neonatal WT and Ptch1+/- mice. We identified a subset of miRNAs, namely let-7 family and miR-17~92 cluster members, whose expression is altered in GCPs by radiation alone, or by synergistic interaction of radiation with Shh-deregulation. The same miRNAs were further validated in spontaneous and radiation-induced MBs from Ptch1+/- mice, confirming persistent deregulation of these miRNAs in the pathogenesis of MB.Our results support the hypothesis that miRNAs dysregulation is associated with radiosensitivity of GCPs and their neoplastic transformation in vivo.

MicroRNAs (miRNAs) regulate gene expression in response to biotic and abiotic stress in plants. We investigated gamma-ray-responsive miRNAs in Arabidopsis wild-type and cmt3-11t mutant plants using miRNA microarray analysis. miRNA expression was differentiated between the wild-type and cmt3-11t mutants. miR164a, miR169d, miR169h, miR172b*, and miR403 were identified as repressible in the wild-type and/or cmt3-11t mutant in response to gamma irradiation, while miR827, miR840, and miR850 were strongly inducible. These eight miRNA genes contain UV-B-responsive cis-elements, including G-box, I-box core, ARE, and/or MBS in the putative promoter regions. Moreover, Box 4, MBS, TCA-element, and Unnamed&#95;4, as well as CAAT- and TATA-box, were identified in these eight miRNA genes. However, a positive correlation between the transcriptions of miRNAs and their putative target genes was only observed between miR169d and At1g30560 in the wild-type, and between miR827 and At1g70700 in the cmt3-11t mutant. Quantitative RT-PCR analysis confirmed that the transcription of miR164a, miR169d, miR169h, miR172b*, miR403, and miR827 differed after gamma irradiation depending on the genotype (wild-type, cmt3-11t, drm2, drd1-6, and ddm1-2) and developmental stage (14 or 28 days after sowing). In contrast, high transcriptional induction of miR840 and miR850 was observed in these six genotypes regardless of the developmental stage. Although the actual target genes and functions of miR840 and miR850 remain to be determined, our results indicate that these two miRNAs may be strongly induced and reproducible genetic markers in Arabidopsis plants exposed to gamma rays., Competing Interests: The authors declare no conflict of interest.

To elucidate the mechanism of radioresistance in non-small cell lung cancer (NSCLC) cells and to identify key molecules conferring radioresistance, the radioresistant subclone NCI-H520/R, derived from the NCI-H520 NSCLC cell line, was established with eight rounds of sublethal irradiation. The radioresistant features were subsequently assessed using a clonogenic assay, analysis of apoptosis and an MTT assay, the gene expression levels were examined using an Agilent Whole Human Genome 4 x 44 k Oligo microarray and Agilent Human miRCURY(™) LNA array, and confirmed by reverse transcription-quantitative polymerase chain reaction. Pathway analysis and Gene Ontology (GO) analysis were performed to determine the biological functions of the subset of differentially expressed genes. miRNA-mRNA correlation analysis between the expression levels of each miRNA and all its predicted target genes was performed to further understand the radioresistance in the NCI-H520 cells. Following eight rounds of sublethal irradiation, a total of 2,862 mRNAs were significantly differentially expressed in the NCI-H520/R cells, including 893 upregulated genes and 1,969 downregulated genes. A total of 162 upregulated miRNAs and 274 downregulated miRNAs were significantly deregulated in the NCI-H520/R cells. Multiple core regulatory processes and signaling pathways were identified as being of likely relevance to radioresistance in NCI-H520/R cells, including the mitogen-activated protein kinase signaling pathway and neurotrophin signaling pathway. The expression of genes associated with radioresistance reflects the complex biological processes involved in clinical cancer cell eradication and requires further investigation for future enhancement of therapy.

Purpose: MicroRNAs (miRNA) play a paramount role in growth, differentiation, proliferation and cell death by suppressing one or more target genes. However, their interaction with radiofrequencies is still unknown. The aim of this study was to investigate the long-term effects of radiofrequency radiation emitted from a Wireless Fidelity (Wi-Fi) system on some of the miRNA in brain tissue., Materials and Methods: The study was carried out on 16 Wistar Albino adult male rats by dividing them into two groups such as sham (n = 8) and exposure (n = 8). Rats in the exposure group were exposed to 2.4 GHz radiofrequency (RF) radiation for 24 hours a day for 12 months (one year). The same procedure was applied to the rats in the sham group except the Wi-Fi system was turned off. Immediately after the last exposure, rats were sacrificed and their brains were removed. miR-9-5p, miR-29a-3p, miR-106b-5p, miR-107, miR-125a-3p in brain were investigated in detail., Results: The results revealed that long-term exposure of 2.4 GHz Wi-Fi radiation can alter expression of some of the miRNAs such as miR-106b-5p (adj p* = 0.010) and miR-107 (adj p* = 0.005). We observed that mir 107 expression is 3.3 times and miR- 106b-5p expression is 3.65 times lower in the exposure group than in the control group. However, miR-9-5p, miR-29a-3p and miR-125a-3p levels in brain were not altered., Conclusion: Long-term exposure of 2.4 GHz RF may lead to adverse effects such as neurodegenerative diseases originated from the alteration of some miRNA expression and more studies should be devoted to the effects of RF radiation on miRNA expression levels.

MicroRNAs (miRNAs) are small, non-coding RNAs that negatively regulate gene expression and have emerged as potential biomarkers in radiation response to human cancer. Only a few miRNAs have been identified in radiation response to prostate cancer and the involvement of the radiation-associated miRNA machinery in the response of prostate cancer cells to radiation is not thoroughly understood. Therefore, the purpose of the present study was to comprehensively investigate the expression levels, arm selection preference and isomiRs of radiation-response miRNAs in radiation-treated PC3 cells using a next-generation sequencing (NGS) approach. Our data revealed that the arm selection preference and 3' modification of miRNAs may be altered in prostate cancer after radiation exposure. In addition, the proportion of AA dinucleotide modifications at the end of the read gradually increased in a time-dependent manner after PC3 radiation treatment. We also identified 6 miRNAs whose expression increased and 16 miRNAs whose expression decreased after exposure to 10 Gy of radiation. A pathway enrichment analysis revealed that the target genes of these radiation-induced miRNAs significantly co-modulated the radiation response pathway, including the mitogen-activated protein kinase (MAPK), Wnt, transforming growth factor-β (TGF-β) and ErbB signaling pathways. Furthermore, analysis of The Cancer Genome Atlas (TCGA) database revealed that the expression of these radiation-induced miRNAs was frequently dysregulated in prostate cancer. Our study identified radiation-induced miRNA candidates which may contribute to radiosensitivity and can be used as biomarkers for radiotherapy.

Photoaging is cell aging caused by long-wave ultraviolet (UVA) radiation which is the main cause of human skin aging produced by exogenous environment. As an endogenous noncoding small RNA, microRNAs (miRNAs) are sensitive to environmental changes, and the expression change of miRNAs is an important manner to adjust to environment. However, the miRNA profile on photoaged human skin irradiated with UVA remains unknown and whether UVA responsive miRNAs participate in the UVA-caused stress reaction of skin cells is also unclear. In this study, we established an in vitro photoaging model with UVA-radiated human primary cultured fibroblasts, which could mimic UVA-induced photoaging of skin. Differentially expressed miRNAs during photoaging, including five up- and seven downregulated miRNAs, were found by microarray analysis and were verified by quantitative real-time PCR. With bioinformatics methods, the predicted miRNA targets were suggested to be associated with pathways in cancers. Among the significantly UVA-downregulated miRNAs, miR-146a overexpression antagonized the UVA-induced proliferation inhibition and suppressed the upregulation of aging-related genes in photoaging of our model. Western blot and luciferase assay showed that Smad4 might be a target of miR-146a to exert miR-146a functions during photoaging. Therefore, UVA radiation-induced photoaging results in specific patterns of miRNA response and miR-146a are able to antagonize UVA-caused photoaging partially through targeting Smad4.

MicroRNAs (miRNAs), a class of non-coding small endogenous RNAs of approximately 22 nucleotides, regulate gene expression at the post-transcriptional levels by targeting mRNAs for degradation or by inhibiting protein translation. Thousands of miRNAs have been identified in many species. However, there is no information available concerning miRNAs in ma bamboo (Dendrocalamus latiflorus), one of the most important non-timber forest products, which has essential ecological roles in forests. To identify miRNAs in D. latiflorus, a small RNA library was constructed from leaf tissues. Using next generation high-throughput sequencing technology and bioinformatics analysis, we obtained 11,513,607 raw sequence reads and identified 84 conserved miRNAs (54 mature miRNAs and 30 star miRNAs) belonging to 17 families, and 81 novel miRNAs (76 mature miRNAs and five star miRNAs) in D. latiflorus. One hundred and sixty-two potential targets were identified for the 81 novel bamboo miRNAs. Several targets for the novel miRNAs are transcription factors that play important roles in plant development. Among the novel miRNAs, 30 were selected and their expression profiles in response to different light conditions were validated by qRT-PCR. This study provides the first large-scale cloning and characterization of miRNAs in D. latiflorus. Eighty-four conserved and 81 novel miRNAs were identified in D. latiflorus. Our results present a broad survey of bamboo miRNAs based on experimental and bioinformatics analysis. Although it will be necessary to validate the functions of miRNAs by further experimental research, these results represent a starting point for future research on D. latiflorus and related species.

Gene regulation in cells exposed to ionizing radiation (IR) occurs at the transcriptional and post-transcriptional levels. Recent studies have suggested that micro-RNA (miRNA) play a significant role in post-transcriptional gene regulation in irradiated cells. miRNA are RNA molecules 18-24 nucleotides in length that are involved in negatively regulating the stability or translation of target messenger RNA. Previous studies from our laboratory have shown that the expression of various miRNA is altered in IR-treated cells. In the present study we monitored genome-wide expression changes of miRNA transcriptome by massively parallel sequencing of human cells irradiated with X-rays. The baseline expression of 402 miRNA indicated a wide range of modulation without exposure to IR. Differences in the expression of many miRNA were observed in a time-dependent fashion following radiation treatment. The Short Time-series Expression Miner (STEM) clustering tool was used to characterize 190 miRNA to six statistically significant temporal expression profiles. miR-19b and miR-93 were induced and miR-222, miR-92a, and miR-941 were repressed after radiation treatment. miR-142-3p, miR-142-5p, miR-107, miR-106b, miR-191, miR-21, miR-26a, miR-182, miR-16, miR-146a, miR-22 and miR-30e exhibited two peaks of induction: one at 8 h and the other at 24 h post-irradiation. miR-378, miR-let-7a, miR-let-7g, miR-let-7f, miR-103b, miR-486-3p, miR-423-5p, miR-4448, miR-3607-5p, miR-20b, miR-130b, miR-155, miR-181, miR-30d and miR-378c were induced only at the 8-h time-point. This catalogue of the inventory of miRNA that are modulated as a response to radiation exposure will be useful for explaining the mechanisms of gene regulation under conditions of stress.

Cellular responses to DNA damage induced by intrinsic and extrinsic genotoxic stresses are highly regulated by complex signaling pathways, such as activation of the phosphoinositide-3-kinase-like protein kinase family and their downstream genes. Disruption of these signaling pathways leads to genome instability and cell death, and thus may provide potential novel strategies for cancer therapy. Here, we find that the expression of a human microRNA (miRNA), hsa-miR-185, is downregulated in response to ionizing radiation. Elevation of miR-185 sensitizes renal cell carcinoma cells to X-rays both in vitro and in vivo. Bioinformatic analysis shows that the ATM- and Rad3-related (ATR) kinase, a master conductor of cellular responses to DNA damage and DNA replication stresses, is a target of miR-185. This prediction was validated by luciferase reporter and mutation assays. We also demonstrated that miR-185 negatively regulates ATR expression at post-transcriptional level. miR-185 enhances radiation-induced apoptosis and inhibition of proliferation by repressing ATR pathway. In conclusion, our findings indicate a previously unreported regulatory mechanism for ATR expression mediated by miR-185 and shed light on the potential application of miRNAs both as direct cancer therapeutics and as tools to sensitize tumor cells to radiotherapy.

Background: Cellular senescence can be induced by a variety of extrinsic stimuli, and sustained exposure to sunlight is a key factor in photoaging of the skin. Accordingly, irradiation of skin fibroblasts by UVB light triggers cellular senescence, which is thought to contribute to extrinsic skin aging, although molecular mechanisms are incompletely understood. Here, we addressed molecular mechanisms underlying UVB induced senescence of human diploid fibroblasts., Results: We observed a parallel activation of the p53/p21(WAF1) and p16(INK4a)/pRb pathways. Using genome-wide transcriptome analysis, we identified a transcriptional signature of UVB-induced senescence that was conserved in three independent strains of human diploid fibroblasts (HDF) from skin. In parallel, a comprehensive screen for microRNAs regulated during UVB-induced senescence was performed which identified five microRNAs that are significantly regulated during the process. Bioinformatic analysis of miRNA-mRNA networks was performed to identify new functional mRNA targets with high confidence for miR-15a, miR-20a, miR-20b, miR-93, and miR-101. Already known targets of these miRNAs were identified in each case, validating the approach. Several new targets were identified for all of these miRNAs, with the potential to provide new insight in the process of UVB-induced senescence at a genome-wide level. Subsequent analysis was focused on miR-101 and its putative target gene Ezh2. We confirmed that Ezh2 is regulated by miR-101 in human fibroblasts, and found that both overexpression of miR-101 and downregulation of Ezh2 independently induce senescence in the absence of UVB irradiation. However, the downregulation of miR-101 was not sufficient to block the phenotype of UVB-induced senescence, suggesting that other UVB-induced processes induce the senescence response in a pathway redundant with upregulation of miR-101., Conclusion: We performed a comprehensive screen for UVB-regulated microRNAs in human diploid fibroblasts, and identified a network of miRNA-mRNA interactions mediating UVB-induced senescence. In addition, miR-101 and Ezh2 were identified as key players in UVB-induced senescence of HDF.

Photodynamic therapy (PDT) is a local tumour treatment accepted for a number of indications. PDT operates via the cellular stress response through the production of reactive oxygen species and subsequent cellular damage, resulting in cell death. Although PDT-induced signalling and cytotoxicity mechanisms have been investigated, the effect of PDT on microRNA (miRNA) expression is largely unknown. Therefore, we conducted a comprehensive microarray-based analysis of the miRNome of human epidermoid carcinoma cells (A431) following in vitro photodynamic treatment using polyvinylpyrrolidone hypericin (PVPH) as a photosensitiser and nearly homogeneous apoptosis-inducing conditions. Using microarray analysis we found eight miRNAs to be significantly differentially expressed 5h post treatment compared with the baseline levels and three miRNAs with more than 2-fold differential expression that could be detected in 1 or 2 biological replicates. The verification of these results by quantitative RT-PCR including a detailed time-course revealed an up to 15-fold transient over-expression of miR-634, miR-1246, miR-1290 and miR-487b compared with the basal level. For these miRNAs, in silico mRNA target prediction yielded numerous target transcripts involved in the regulation of cell stress, apoptosis, cell adherence and proliferation. This study provides the first comprehensive miRNome analysis after PDT treatment and may help to develop novel miRNA-based therapeutic approaches to further increase the efficiency of PDT., (Copyright © 2013 Elsevier B.V. All rights reserved.)

This study aimed to evaluate the protective effects of Centella asiatica (C. asiatica) against ultraviolet B (UVB) damage in human keratinocytes using microRNA (miRNA) expression profiling analysis. Titrated extract of C. asiatica (TECA) demonstrated low cytotoxicity in normal human HaCaT keratinocytes only at low doses (<5 µg/ml). UVB (50 mJ/cm2) irradiation significantly decreased cell viability, and TECA treatment decreased the UVB toxicity. By using miRNA microarrays, we determined that 72 miRNAs had an altered expression following TECA treatment in UVB-irradiated keratinocytes (46 upregulated and 26 downregulated). Using an miRNA target gene prediction tool and Gene Ontology (GO) analysis, we determined that miRNAs with altered expression were functionally related with the inhibition of apoptosis and cell proliferation. Overall, these results provide meaningful information to facilitate the understanding of TECA-mediated UVB protection in human keratinocytes.

We have previously demonstrated that prostate carcinoma cells exposed to fractionated radiation differentially expressed more genes compared to single-dose radiation. To understand the role of miRNA in regulation of radiation-induced gene expression, we analyzed miRNA expression in LNCaP, PC3 and DU145 prostate cancer cells treated with single-dose radiation and fractionated radiation by microarray. Selected miRNAs were studied in RWPE-1 normal prostate epithelial cells by RT-PCR. Fractionated radiation significantly altered more miRNAs as compared to single-dose radiation. Downregulation of oncomiR-17-92 cluster was observed only in the p53 positive LNCaP and RWPE-1 cells treated with single-dose radiation and fractionated radiation. Comparison of miRNA and mRNA data by IPA target filter analysis revealed an inverse correlation between miR-17-92 cluster and several targets including TP53INP1 in p53 signaling pathway. The base level expressions of these miRNAs were significantly different among the cell lines and did not predict the radiation outcome. Tumor suppressor miR-34a and let-7 miRNAs were upregulated by fractionated radiation in radiosensitive LNCaP (p53 positive) and PC3 (p53-null) cells indicating that radiation-induced miRNA expression may not be regulated by p53 alone. Our data support the potential for using fractionated radiation to induce molecular targets and radiation-induced miRNAs may have a significant role in predicting radiosensitivity.

A detailed understanding of the mechanisms that determine the variable cellular sensitivity to radiation is needed for improved radiation therapy as well as for the identification of individuals with innate radiation hypersensitivity. MicroRNAs (miRNAs) are a class of small non-coding RNAs that post-transcriptionally regulate protein expression. Alterations in miRNA expression patterns in response to ionizing radiation have been shown, but there are almost no data describing the functional impact of these miRNA changes. We report here the results of studies on the functional roles of miRNAs in the radiation response in immortalized and primary endothelial cells. Global suppression of miRNA expression was achieved through downregulation of Argonaut e-2 (AGO2) or DICER proteins using RNAi. The reductions in either DICER or AGO2 led to increased cell death after irradiation, indicating a prosurvival function of miRNAs. Furthermore, while cell cycle checkpoint activation and apoptosis were compromised, DNA double-strand break repair was not affected by the lack of miRNAs. The differential sensitivity of these pathways implies the independent activation of the two response pathways rather than a concerted DNA damage response. The miRNAs that were changed after 2.5 Gy irradiation were identified by TaqMan-based low-density array technology. Of the miRNAs showing an upregulation 4 h or 24 h after radiation exposure, we were able to establish prosurvival and antiapoptotic functions for three miRNAs. Taken together, our data indicate a general prosurvival role for miRNA-mediated gene regulation during the radiation response. We show a functional association between miRNAs, apoptosis and cell cycle checkpoint activation in irradiated cells.

This review focuses on a number of recent studies that have examined changes in microRNA (miRNA) expression profiles in response to ionizing radiation and other forms of oxidative stress. In both murine and human cells and tissues, a number of miRNAs display significant alterations in expression levels in response to both direct and indirect radiation exposure. In terms of direct irradiation, or exposure to agents that induce oxidative stress, miRNA array analyses indicate that a number of miRNAs are up- and down-regulated and, in particular, the let-7 family of miRNAs may well be critical in the cellular response to oxidative stress. In bystander cells that are not directly irradiated, but close to, or share media with directly irradiated cells or tissues, the miRNA expression profiles are also altered, but are somewhat distinct from the directly irradiated cells. Based on the results of these numerous studies, as well as our own data presented here, we conclude that miRNA regulation is a critical step in the cellular response to radiation and oxidative stress and that future studies should elucidate the mechanisms through which this altered regulation affects cell metabolism.