Regulation of type I collagen expression by microRNA-29 following ionizing radiation

Non-coding RNAs and their potential exploitation in cancer therapy-related cardiotoxicity

Life expectancy in cancer patients has been extended in recent years, thanks to major breakthroughs in therapeutic developments. However, this also unmasked an increased incidence of cardiovascular diseases in cancer survivors, which is in part attributable to cancer therapy-related cardiovascular toxicity. Non-coding RNAs (ncRNAs) have received much appreciation due to their impact on gene expression. NcRNAs, which include microRNAs, long ncRNAs and circular RNAs, are non-protein-coding transcripts that are involved in the regulation of various biological processes, hence shaping cell identity and behaviour. They have also been implicated in disease development, including cardiovascular diseases, cancer and, more recently, cancer therapy-associated cardiotoxicity. This review outlines key features of cancer therapy-associated cardiotoxicity, what is known about the roles of ncRNAs in these processes and how ncRNAs could be exploited as therapeutic targets for cardioprotection. LINKED ARTICLES: This article is part of a themed issue Non-coding RNA Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v182.2/issuetoc.

Radio-miRs: a comprehensive view of radioresistance-related microRNAs

Radiotherapy is a key treatment option for a wide variety of human tumors, employed either alone or alongside with other therapeutic interventions. Radiotherapy uses high-energy particles to destroy tumor cells, blocking their ability to divide and proliferate. The effectiveness of radiotherapy is due to genetic and epigenetic factors that determine how tumor cells respond to ionizing radiation. These factors contribute to the establishment of resistance to radiotherapy, which increases the risk of poor clinical prognosis of patients. Although the mechanisms by which tumor cells induce radioresistance are unclear, evidence points out several contributing factors including the overexpression of DNA repair systems, increased levels of reactive oxygen species, alterations in the tumor microenvironment, and enrichment of cancer stem cell populations. In this context, dysregulation of microRNAs or miRNAs, critical regulators of gene expression, may influence how tumors respond to radiation. There is increasing evidence that miRNAs may act as sensitizers or enhancers of radioresistance, regulating key processes such as the DNA damage response and the cell death signaling pathway. Furthermore, expression and activity of miRNAs have shown informative value in overcoming radiotherapy and long-term radiotoxicity, revealing their potential as biomarkers. In this review, we will discuss the molecular mechanisms associated with the response to radiotherapy and highlight the central role of miRNAs in regulating the molecular mechanisms responsible for cellular radioresistance. We will also review radio-miRs, radiotherapy-related miRNAs, either as sensitizers or enhancers of radioresistance that hold promise as biomarkers or pharmacological targets to sensitize radioresistant cells.

Epigenetic regulation of TGF-β pathway and its role in radiation response

PURPOSE

Transforming growth factor (TGF-β) plays a dual role in tumor progression as well as a pivotal role in radiation response. TGF-β-related epigenetic regulations, including DNA methylation, histone modifications (including methylation, acetylation, phosphorylation, ubiquitination), chromatin remodeling and non-coding RNA regulation, have been found to affect the occurrence and development of tumors as well as their radiation response in multiple dimensions. Due to the significance of radiotherapy in tumor treatment and the essential roles of TGF-β signaling in radiation response, it is important to better understand the role of epigenetic regulation mechanisms mediated by TGF-β signaling pathways in radiation-induced targeted and non-targeted effects.

CONCLUSIONS

By revealing the epigenetic mechanism related to TGF-β-mediated radiation response, summarizing the existing relevant adjuvant strategies for radiotherapy based on TGF-β signaling, and discovering potential therapeutic targets, we hope to provide a new perspective for improving clinical treatment.

Analysis of circRNA-miRNA-mRNA Regulatory Network in Peripheral Blood of Radiation Workers

The health of radiation workers has always been our focus. Epidemiological investigation shows that long-term exposure to low-dose ionizing radiation can affect human health, especially cancer and cardiovascular disease, and there are many studies on it. However, up to now, there have been few reports on the research of blood and biological samples from radiation workers. In this study, radiation workers and healthy control groups were strictly screened, and the transcriptome of mRNA and circRNA was sequenced by extracting their peripheral venous blood. At the same time, appropriate data sets were selected in the GEO database for bioinformatics analysis, and circRNA-miRNA-mRNA network was constructed. We identified 9 different circular ribonucleic acids, 3 tiny ribonucleic acids, and 2 central genes (NOD 2 and IRF 7). These differentially expressed genes and non-coding RNA are closely related to ionizing radiation damage, and play an important role as biological markers. In conclusion, this study may provide new insights into the role of the circRNA-miRNA-mRNA regulatory network in the health of radiation workers, and provides a new strategy for the future study of radiation biology.

Targeting Chitinase 1 and Chitinase 3-Like 1 as Novel Therapeutic Strategy of Pulmonary Fibrosis

Chitinase 1 (CHIT1) and chitinase 3-like-1 (CHI3L1), two representative members of 18-Glycosyl hydrolases family, are significantly implicated in the pathogenesis of various human diseases characterized by inflammation and remodeling. Notably, dysregulated expression of CHIT1 and CHI3L1 was noted in the patients with pulmonary fibrosis and their levels were inversely correlated with clinical outcome of the patients. CHIT1 and CHI3L1, mainly expressed in alveolar macrophages, regulate profibrotic macrophage activation, fibroblast proliferation and myofibroblast transformation, and TGF-β signaling and effector function. Although the mechanism or the pathways that CHIT1 and CHI3L1 use to regulate pulmonary fibrosis have not been fully understood yet, these studies identify CHIT1 and CHI3L1 as significant modulators of fibroproliferative responses leading to persistent and progressive pulmonary fibrosis. These studies suggest a possibility that CHIT1 and CHI3L1 could be reasonable therapeutic targets to intervene or reverse established pulmonary fibrosis. In this review, we will discuss specific roles and regulatory mechanisms of CHIT1 and CHI3L1 in profibrotic cell and tissue responses as novel therapeutic targets of pulmonary fibrosis.

Targeting Type I Collagen for Cancer Treatment

Collagen is the most abundant protein in animals. Interactions between tumor cells and collagen influence every step of tumor development. Type I collagen is the main fibrillar collagen in the extracellular matrix and is frequently up-regulated during tumorigenesis. The binding of type I collagen to its receptors on tumor cells promotes tumor cell proliferation, epithelial-mesenchymal transition, and metastasis. Type I collagen also regulates the efficacy of tumor therapies, such as chemotherapy, radiotherapy, and immunotherapy. Furthermore, type I collagen fragments are diagnostic markers of metastatic tumors and have prognostic value. Inhibition of type I collagen synthesis has been reported to have anti-tumor effects in animal models. However, collagen has also been shown to possess anti-tumor activity. Therefore, the roles that type I collagen plays in tumor biology are complex and tumor type-dependent. In this review, we discuss the expression and regulation of synthesis of type I collagen, as well as the role up-regulated type I collagen plays in various stages of cancer progression. We also discuss the role of collagen in tumor therapy. Finally, we highlight several recent approaches targeting type I collagen for cancer treatment. This article is protected by copyright. All rights reserved.

MicroRNA-26 regulates the expression of CTGF after exposure to ionizing radiation

Radiation-induced fibrosis (RIF) is a serious complication that occurs after irradiation and which is caused by the deposition of extracellular matrix (ECM) proteins such as collagen. However, the underlying mechanisms, including the expression of the cytokines, that promote the RIF process, are not yet fully understood. MicroRNAs (miRNAs) have recently been suggested to act as post-transcriptional repressors for many genes; however, their role in the process of RIF remains to be elucidated. Our previous study showed that ionizing radiation increased the type I collagen expression through the activation of transforming growth factor (TGF)-β, while miR-29 repressed this increase. This study aimed to investigate the mechanisms by which the expression of connective tissue growth factor (CTGF), a downstream mediator of TGF-β, is controlled by miRNAs post-transcriptionally after exposure to ionizing radiation. The expression of CTGF in NIH-3T3 cells and mouse embryonic fibroblasts was increased by ionizing radiation. However, this increase was suppressed with a specific inhibitor of TGF-β receptor. Among the predictable miRNAs that target the CTGF gene, the expression of miR-26a was downregulated after exposure to ionizing radiation and this regulation was negatively mediated by TGF-β signaling. miR-26a negatively regulated the CTGF expression at the post-transcriptional level; however, ionizing radiation suppressed this negative regulation. In addition, the overexpression of miR-26a inhibited the expression of CTGF and type I collagen after irradiation. In conclusion, miR-26a modulates the expression of CTGF via TGF-β signaling in irradiated fibroblasts. The results suggest the potential application of miR-26a in the treatment of RIF.

MicroRNA: a novel implication for damage and protection against ionizing radiation

Ionizing radiation (IR) is a form of high energy. It poses a serious threat to organisms, but radiotherapy is a key therapeutic strategy for various cancers. It is significant to reduce radiation injury but maximize the effect of radiotherapy. MicroRNAs (miRNAs) are posttranscriptionally regulatory factors involved in cellular radioresponse. In this review, we show how miRNAs regulate important genes on cellular response to IR-induced damage and how miRNAs participate in IR-induced carcinogenesis. Additionally, we summarize the experimental and clinical evidence for miRNA involvement in radiotherapy and discuss their potential for improvement of radiotherapy. Finally, we highlight the role that miRNAs play in accident exposure to IR or radiotherapy as predictive biomarker. miRNA therapeutics have shown great perspective in radiobiology; miRNA may become a novel strategy for damage and protection against IR.

Administration of TGF-ß Inhibitor Mitigates Radiation-induced Fibrosis in a Mouse Model

BACKGROUND

Radiation-induced fibrosis is a long-term adverse effect of external beam radiation therapy for cancer treatment that can cause pain, loss of function, and decreased quality of life. Transforming growth factor beta (TGF-β) is believed to be critical to the development of radiation-induced fibrosis, and TGF-β inhibition decreases the development of fibrosis. However, no treatment exists to prevent radiation-induced fibrosis. Therefore, we aimed to mitigate the development of radiation-induced fibrosis in a mouse model by inhibiting TGF-β.

QUESTION/PURPOSES

Does TGF-β inhibition decrease the development of muscle fibrosis induced by external beam radiation in a mouse model?

METHODS

Twenty-eight 12-week-old male C57BL/6 mice were assigned randomly to three groups: irradiated mice treated with TGF-βi, irradiated mice treated with placebo, and control mice that received neither irradiation nor treatment. The irradiated mice received one 50-Gy fraction of radiation to the right hindlimb before treatment initiation. Mice treated with TGF-c (n = 10) received daily intraperitoneal injections of a small-molecule inhibitor of TGF-β (1 mg/kg) in a dimethyl sulfoxide vehicle for 8 weeks (seven survived to histologic analysis). Mice treated with placebo (n = 10) received daily intraperitoneal injections of only a dimethyl sulfoxide vehicle for 8 weeks (10 survived to histologic analysis). Control mice (n = 8) received neither radiation nor TGF-β treatment. Control mice were euthanized at 3 months because they were not expected to exhibit any changes related to treatment. Mice in the two treatment groups were euthanized 9 months after radiation, and the quadriceps of each thigh was sampled. Masson's trichome stain was used to assess muscle fibrosis. Slides were viewed at 10 × magnification using bright-field microscopy, and in a blinded fashion, five representative images per mouse were used to quantify fibrosis. The mean ± SD fibrosis pixel densities in the TGF-βi and radiation-only groups were compared using Mann-Whitney U tests. The ratio of fibrosis to muscle was calculated using the mean fibrosis per slide in the TGF-βi group to standardize measurements. Alpha was set at 0.05.

RESULTS

The mean (± SD) percentage of fibrosis per slide was greater in the radiation-only group (1.2% ± 0.42%) than in the TGF-βi group (0.14% ± 0.09%) (odds ratio 0.12 [95% CI 0.07 to 0.20]; p < 0.001). Among control mice, mean fibrosis was 0.05% ± 0.02% per slide. Mice in the radiation-only group had 9.1 times the density of fibrosis as did mice in the TGF-βi group.

CONCLUSION

Our study provides preliminary evidence that the fibrosis associated with radiation therapy to a quadriceps muscle can be reduced by treatment with a TGF-β inhibitor in a mouse model.

CLINICAL RELEVANCE

If these observations are substantiated by further investigation into the role of TGF-β inhibition on the development of radiation-induced fibrosis in larger animal models and humans, our results may aid in the development of novel therapies to mitigate this complication of radiation treatment.

Radiation-induced skin injury: pathogenesis, treatment, and management

Radiation-induced skin injury (RSI) refers to a frequently occurring complication of radiation therapy. Nearly 90% of patients having received radiation therapy underwent moderate-to-severe skin reactions, severely reducing patients' quality of life and adversely affecting their disease treatment. No gold standard has been formulated for RSIs. In the present study, the mechanism of RSI and topical medications was discussed. Besides, this study can be referenced for clinicians to treat RSIs to guide subsequent clinical medicine.

Mesenchymal stem cell-derived extracellular vesicles suppress the fibroblast proliferation by downregulating FZD6 expression in fibroblasts via micrRNA-29b-3p in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF), a progressive and fatal lung disease, usually leads to an irreversible distortion of the pulmonary structure. The functional roles of bone marrow-derived mesenchymal stem cells (BMSC)-secreted extracellular vesicles (EVs) in fibroblasts have been implicated, yet their actions in the treatment of IPF are not fully understood. This study investigated the roles of BMSC-derived EVs expressing miR-29b-3p in fibroblasts in IPF treatment. EVs derived from BMSCs were successfully isolated and could be internalized by pulmonary fibroblasts, and Cell Counting Kit-8 (CCK-8) and Transwell assay results identified that EVs inhibited the activation of fibroblast in IPF. miR-29b-3p, frizzled 6 (FZD6), α-skeletal muscle actin (α-SMA), and Collagen I expressions were examined, which revealed that miR-29b-3p was poorly expressed and FZD6, α-SMA, and Collagen I were overexpressed in pulmonary tissues. Dual-luciferase reporter assay results demonstrated that miR-29b-3p could inversely target FZD6 expression. The gain- and loss-of-function assays were conducted to determine regulatory effects of FZD6 and miR-29b-3p on IPF. CCK-8 and Transwell assays results displayed that BMSCs-derived EVs overexpressing miR-29b-3p contributed to inhibited pulmonary interstitial fibroblast proliferation, migration, invasion, and differentiation. Furthermore, the effects of BMSCs-derived EVs overexpressing miR-29b-3p on IPF progression were assessed in vivo, which confirmed the repressive effects of BMSCs-derived EVs overexpressing miR-29b-3p on IPF progression. Collectively, BMSCs-derived EVs overexpressing miR-29b-3p relieve IPF through FZD6.

The Involvement of SDF-1α/CXCR4 Axis in Radiation-Induced Acute Injury and Fibrosis of Skin

Radiation-induced acute skin injury and consequent fibrosis are common complications of cancer radiotherapy and radiation accidents. Stromal cell-derived factor-1α (SDF-1α) and its receptor, CXC chemokine receptor 4 (CXCR4) have been shown to be involved in multiple cellular events. However, the role of SDF-1α/CXCR4 axis in radiation-induced acute injury and fibrosis of skin has not been reported. In this study, we found that the expression of SDF-1α and CXCR4 was significantly increased in irradiated skin tissues of humans, monkeys and rats, compared to their nonirradiated counterparts. Mice with keratinocyte-specific ablation of CXCR4 showed less severe skin damage than wild-type mice after receiving a 35 Gy dose of radiation. Consistently, subcutaneous injection of AMD3100, an FDA approved SDF-1α/CXCR4 inhibitor, attenuated skin injury and fibrosis induced by exposure to radiation in a rat model. Mechanically, the SDF-1α/CXCR4 axis promotes pro-fibrotic TGF-b/Smad signaling through the PI3K-MAPK signaling cascade in human keratinocyte HaCaT cells and skin fibroblast WS1 cells. AMD3100 inhibited Smad2 nuclear translocation and transcriptional activity of Smad2/3 induced by radiation, which suppressed the pro-fibrotic TGF-b/Smad signaling pathway activated by exposure. Taken together, these findings demonstrate the involvement of SDF-1α/CXCR4 axis in radiation-induced acute injury and fibrosis of skin, and indicate that AMD3100 would be an effective countermeasure against these diseases.

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.

A Systematic Review of miR-29 in Cancer

MicroRNAs (miRNA) are small non-coding RNAs (∼22 nt in length) that are known as potent master regulators of eukaryotic gene expression. miRNAs have been shown to play a critical role in cancer pathogenesis, and the misregulation of miRNAs is a well-known feature of cancer. In recent years, miR-29 has emerged as a critical miRNA in various cancers, and it has been shown to regulate multiple oncogenic processes, including epigenetics, proteostasis, metabolism, proliferation, apoptosis, metastasis, fibrosis, angiogenesis, and immunomodulation. Although miR-29 has been thoroughly documented as a tumor suppressor in the majority of studies, some controversy remains with conflicting reports of miR-29 as an oncogene. In this review, we provide a systematic overview of miR-29's functional role in various mechanisms of cancer and introspection on the contradictory roles of miR-29.

Transcriptional activation of miR-320a by ATF2, ELK1 and YY1 induces cancer cell apoptosis under ionizing radiation conditions

MicroRNAs (miRNAs or miRs) play important roles in numerous cellular processes, including development, proliferation, tumorigenesis and apoptosis. It has been reported that miRNA expression is induced by ionizing radiation (IR) in cancer cells. However, the underlying molecular mechanisms are not yet fully understood. In this study, endogenous miR‑320a and its primary precursor (pri‑miR‑320a) were assayed by reverse transcription‑quantitative PCR (RT‑qPCR). Luciferase activities were measured using a dual‑luciferase reporter assay system. Western blot analysis was used to determine the protein expressions of upstream and downstream genes of miR‑320a. Cell apoptosis was evaluated by Annexin V apoptosis assay and cell proliferation was measured using the trypan blue exclusion method. The results revealed that miR‑320a expression increased linearly with the IR dose and treatment duration. Three transcription factors, activating transcription factor 2 (ATF2), ETS transcription factor (ELK1) and YY1 transcription factor (YY1), were activated by p38 mitogen‑activated protein kinase (MAPK) and mitogen‑activated protein kinase 8 (JNK) and by upregulated miR‑320a expression under IR conditions. In addition, it was identified that X‑linked inhibitor of apoptosis (XIAP) was an miR‑320a target gene during the IR response. By targeting XIAP, miR‑320a induced apoptosis and inhibited the proliferation of the cancer cells. On the whole, the results of this study demonstrated that miRNA‑320a, regulated by the p38 MAPK/JNK pathway, enhanced the radiosensitivity of cancer cells by inhibiting XIAP and this may thus prove to be a potential therapeutic approach with which to overcome radioresistance in cancer treatment.