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Hassel JC, Zimmer L, Sickmann T, Eigentler TK, Meier F, Mohr P, Pukrop T, Roesch A, Vordermark D, Wendl C, Gutzmer R. Medical Needs and Therapeutic Options for Melanoma Patients Resistant to Anti-PD-1-Directed Immune Checkpoint Inhibition. Cancers (Basel) 2023; 15:3448. [PMID: 37444558 DOI: 10.3390/cancers15133448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/15/2023] Open
Abstract
Available 4- and 5-year updates for progression-free and for overall survival demonstrate a lasting clinical benefit for melanoma patients receiving anti-PD-directed immune checkpoint inhibitor therapy. However, at least one-half of the patients either do not respond to therapy or relapse early or late following the initial response to therapy. Little is known about the reasons for primary and/or secondary resistance to immunotherapy and the patterns of relapse. This review, prepared by an interdisciplinary expert panel, describes the assessment of the response and classification of resistance to PD-1 therapy, briefly summarizes the potential mechanisms of resistance, and analyzes the medical needs of and therapeutic options for melanoma patients resistant to immune checkpoint inhibitors. We appraised clinical data from trials in the metastatic, adjuvant and neo-adjuvant settings to tabulate frequencies of resistance. For these three settings, the role of predictive biomarkers for resistance is critically discussed, as well as are multimodal therapeutic options or novel immunotherapeutic approaches which may help patients overcome resistance to immune checkpoint therapy. The lack of suitable biomarkers and the currently modest outcomes of novel therapeutic regimens for overcoming resistance, most of them with a PD-1 backbone, support our recommendation to include as many patients as possible in novel or ongoing clinical trials.
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Affiliation(s)
- Jessica C Hassel
- Skin Cancer Center, Department of Dermatology and National Center for Tumor Diseases (NCT), University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Lisa Zimmer
- Department of Dermatology, University Hospital Essen, 45147 Essen, Germany
- German Cancer Consortium (DKTK), Partner Site Essen, 69120 Heidelberg, Germany
| | | | - Thomas K Eigentler
- Department of Dermatology, Venereology and Allergology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
| | - Friedegund Meier
- Department of Dermatology, Skin Cancer Center at the University Cancer Centre and National Center for Tumor Diseases, Faculty of Medicine and University Hospital Carl Gustav Carus, Technical University Dresden, 01062 Dresden, Germany
| | - Peter Mohr
- Department of Dermatology, Elbe-Kliniken, 21614 Buxtehude, Germany
| | - Tobias Pukrop
- Department of Internal Medicine III, Hematology and Oncology, University Hospital Regensburg, 93053 Regensburg, Germany
- Bavarian Cancer Research Center (BZKF), 93053 Regensburg, Germany
| | - Alexander Roesch
- Department of Dermatology, University Hospital Essen, 45147 Essen, Germany
| | - Dirk Vordermark
- Department for Radiation Oncology, Martin-Luther University Halle-Wittenberg, 06108 Halle, Germany
| | - Christina Wendl
- Department of Radiology, University Hospital Regensburg, 93053 Regensburg, Germany
| | - Ralf Gutzmer
- Department of Dermatology, Johannes Wesling Medical Center, Ruhr University Bochum, 32429 Minden, Germany
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Krishnaraj J, Yamamoto T, Ohki R. p53-Dependent Cytoprotective Mechanisms behind Resistance to Chemo-Radiotherapeutic Agents Used in Cancer Treatment. Cancers (Basel) 2023; 15:3399. [PMID: 37444509 DOI: 10.3390/cancers15133399] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/20/2023] [Accepted: 06/22/2023] [Indexed: 07/15/2023] Open
Abstract
Resistance to chemoradiotherapy is the main cause of cancer treatment failure. Cancer cells, especially cancer stem cells, utilize innate cytoprotective mechanisms to protect themselves from the adverse effects of chemoradiotherapy. Here, we describe a few such mechanisms: DNA damage response (DDR), immediate early response gene 5 (IER5)/heat-shock factor 1 (HSF1) pathway, and p21/nuclear factor erythroid 2-related factor 2 (NRF2) pathway, which are regulated by the tumour suppressor p53. Upon DNA damage caused during chemoradiotherapy, p53 is recruited to the sites of DNA damage and activates various DNA repair enzymes including GADD45A, p53R2, DDB2 to repair damaged-DNA in cancer cells. In addition, the p53-IER5-HSF1 pathway protects cancer cells from proteomic stress and maintains cellular proteostasis. Further, the p53-p21-NRF2 pathway induces production of antioxidants and multidrug resistance-associated proteins to protect cancer cells from therapy-induced oxidative stress and to promote effusion of drugs from the cells. This review summarises possible roles of these p53-regulated cytoprotective mechanisms in the resistance to chemoradiotherapy.
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Affiliation(s)
- Jayaraman Krishnaraj
- Laboratory of Fundamental Oncology, National Cancer Center Research Institute, Tsukiji 5-1-1, Chuo-ku, Tokyo 104-0045, Japan
| | - Tatsuki Yamamoto
- Laboratory of Fundamental Oncology, National Cancer Center Research Institute, Tsukiji 5-1-1, Chuo-ku, Tokyo 104-0045, Japan
| | - Rieko Ohki
- Laboratory of Fundamental Oncology, National Cancer Center Research Institute, Tsukiji 5-1-1, Chuo-ku, Tokyo 104-0045, Japan
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Regulation of DNA damage response by trimeric G-proteins. iScience 2023; 26:105973. [PMID: 36756378 PMCID: PMC9900518 DOI: 10.1016/j.isci.2023.105973] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 08/14/2022] [Accepted: 01/10/2023] [Indexed: 01/14/2023] Open
Abstract
Upon sensing DNA double-strand breaks (DSBs), eukaryotic cells either die or repair DSBs via one of the two competing pathways, i.e., non-homologous end-joining (NHEJ) or homologous recombination (HR). We show that cell fate after DSBs hinges on GIV/Girdin, a guanine nucleotide-exchange modulator of heterotrimeric Giα•βγ protein. GIV suppresses HR by binding and sequestering BRCA1, a key coordinator of multiple steps within the HR pathway, away from DSBs; it does so using a C-terminal motif that binds BRCA1's BRCT-modules via both phospho-dependent and -independent mechanisms. Using another non-overlapping C-terminal motif GIV binds and activates Gi and enhances the "free" Gβγ→PI-3-kinase→Akt pathway, which promotes survival and is known to suppress HR, favor NHEJ. Absence of GIV, or loss of either of its C-terminal motifs enhanced cell death upon genotoxic stress. Because GIV selectively binds other BRCT-containing proteins suggests that G-proteins may fine-tune sensing, repair, and survival after diverse types of DNA damage.
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Ding L, Zhao X, Xiong Q, Jiang X, Liu X, Ding K, Zhou P. Cdc25B is transcriptionally inhibited by IER5 through the NF-YB transcription factor in irradiation-treated HeLa cells. Toxicol Res (Camb) 2021; 10:875-884. [PMID: 34484679 DOI: 10.1093/toxres/tfab069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 05/28/2021] [Accepted: 07/05/2021] [Indexed: 12/09/2022] Open
Abstract
Cervical cancer (CC) is a type of pelvic malignant tumor that severely threatens women's health. Current evidence suggests that IER5, as a potential radiosensitizer, promotes irradiation-induced apoptosis in CC tissues in patients undergoing chemoradiotherapy. IER5 has been shown to be involved in the G2/M-phase transition. In the present study, we used Cdc25B as the breakthrough point to explore the underlying mechanism of IER5 in the cell cycle regulation of radiation-damaged HeLa cells. IER5 was evidently upregulated after irradiation, but Cdc25B was significantly downregulated. In monoclonal IER5-silenced HeLa cells, irradiation-induced downregulation of Cdc25B was attenuated. The effect of irradiation on Cdc25B promoter activity was determined by dual-luciferase reporter assays. The response elements on the Cdc25B promoter related to irradiation were predicted by JASPAR. These conserved sequences were mutated individually or in combination by splicing-by-overlap extension PCR, and their function was confirmed by dual-luciferase reporter assays. The enrichment efficiency of transcription factors after irradiation was determined by chromatin immunoprecipitation (ChIP) assay. Both Sp1/Sp3 and NF-YB binding sites were involved in irradiation-mediated regulation of Cdc25B. IER5 was involved in irradiation-mediated regulation of Cdc25B through the NF-YB binding site. Furthermore, ChIP assays showed that IER5 bound to the Cdc25B promoter, and the binding of IER5 to the Cdc25B promoter region in irradiation-induced HeLa cells induced the release of the coactivator p300 through interaction with NF-YB. Taken together, these findings indicate that IER5 is the transcriptional repressor that accelerates the downregulation of Cdc25B expression after irradiation.
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Affiliation(s)
- Lixin Ding
- National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Xicheng District, Beijing 100088, P. R. China
| | - Xianzhe Zhao
- National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Xicheng District, Beijing 100088, P. R. China
| | - Qiang Xiong
- National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Xicheng District, Beijing 100088, P. R. China
| | - Xiaoyan Jiang
- National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Xicheng District, Beijing 100088, P. R. China
| | - Xiaodan Liu
- Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Haidian District, Beijing 100850, P. R. China
| | - Kuke Ding
- National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Xicheng District, Beijing 100088, P. R. China
| | - Pingkun Zhou
- Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Haidian District, Beijing 100850, P. R. China
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Abd El-hafeez AA, Sun N, Chakraborty A, Ear J, Roy S, Chamarthi P, Rajapakse N, Das S, Luker KE, Hazra TK, Luker GD, Ghosh P. Regulation of DNA damage response by trimeric G-protein Signaling.. [DOI: 10.1101/2021.07.21.452842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
AbstractUpon sensing DNA double-strand breaks (DSBs), eukaryotic cells either die or repair DSBs via one of two competing pathways, i.e., non-homologous end-joining (NHEJ) or homologous recombination (HR). We show that cell fate after DNA damage hinges on the guanine nucleotide-exchange modulator of heterotrimeric G-protein, Giα•βγ, GIV/Girdin. GIV suppresses HR by binding and sequestering BRCA1, a key coordinator of multiple steps within the HR pathway, away from DSBs; it does so using a C-terminal motif that binds BRCA1’s BRCT-modules via both phospho-dependent and -independent mechanisms. GIV promotes NHEJ, and binds and activates Gi and enhances the ‘free’ Gβγ→PI-3-kinase→Akt pathway, thus revealing the enigmatic origin of prosurvival Akt signals during dsDNA repair. Absence of GIV, or the loss of either of its two functions impaired DNA repair, and induced cell death when challenged with numerous cytotoxic agents. That GIV selectively binds few other BRCT-containing proteins suggests convergent signaling such that heterotrimeric G-proteins may finetune sensing, repair, and outcome after DNA damage.GRAPHIC ABSTRACTHIGHLIGHTSNon-receptor G protein modulator, GIV/Girdin binds BRCA1Binding occurs in both canonical and non-canonical modesGIV sequesters BRCA1 away from dsDNA breaks, suppresses HRActivation of Gi by GIV enhances Akt signals, favors NHEJIN BRIEFIn this work, the authors show that heterotrimeric G protein signaling that is triggered by non-receptor GEF, GIV/Girdin, in response to double-stranded DNA breaks is critical for decisive signaling events which favor non-homologous end-joining (NHEJ) and inhibit homologous recombination (HR).
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Wu Z, Wang D, Zeng F, Zhang Y, Zhu G, Ma Y, Song B, Lui S, Wu M. High IER5 Gene Expression Is Associated With Poor Prognosis in Glioma Patients. Front Cell Dev Biol 2021; 9:679684. [PMID: 34222249 PMCID: PMC8248409 DOI: 10.3389/fcell.2021.679684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/13/2021] [Indexed: 02/05/2023] Open
Abstract
Objective Immediate early response 5 (IER5) plays a core role in cell cycle and response to irradiation. However, its role in glioma remains unclear. We aimed to evaluate its prognostic significance in glioma based on The Cancer Genome Atlas data resource. Methods The Kruskal–Wallis test, Wilcoxon signed-rank test, and logistic regression were employed to explore the relationship between IER5 expression and clinicopathological features. Kaplan–Meier and Cox regression analyses were implemented to investigate the relationship of IER5 with prognosis. A nomogram to estimate the impact of IER5 on prognosis was created based on the Cox multivariate data. We performed gene set enrichment analysis (GSEA) to determine the key signaling cascades associated with IER5. Immunohistochemistry was performed to examine IER5 expression in a tissue microarray (TMA) of glioma samples. Results Immediate early response 5 gene expression was elevated in glioma patients. The level of IER5 was significantly correlated with WHO grade [OR = 6.71 (4.34–10.68) for G4 vs. G2 and G3], IDH (isocitrate dehydrogenase enzyme) status [OR = 13.35 (8.92–20.46) for wild-type (WT) vs. mutated (Mut)], epidermal growth factor receptor status [OR = 8.42 (4.32–18.43) for Mut vs. WT], age [OR = 0.27 (0.18–0.41) for ≤ 60 years vs. >60 years], and histological type [OR = 7.13 (4.63–11.31] for glioblastoma vs. astrocytoma, oligoastrocytoma, and oligodendroglioma). Univariate analyses revealed that high IER5 expression was linked to short overall survival (OS) [hazard ratio (HR): 3.747; 95% confidence interval (CI): 2.847–4.933; and P < 0.001]. High IER5 expression was linked to poor OS in multivariate analyses (HR: 2.474; 95% CI: 1.552–3.943; and P < 0.001). TMA results showed that high IER5 protein levels were related to short OS (HR: 1.84; 95% CI: 1.10–3.07; and P = 0.021) and poor disease-specific survival (HR: 1.82; 95% CI: 1.09–3.04; and P = 0.023). GSEA showed that many tumor related pathways were enriched differentially in the IER5-high expression group. The C-index and calibration plots of the nomogram showed an effective estimation performance in glioma patients. Conclusion Herein, we established that IER5 plays a critical role in glioma progression and prognosis, which might be an important biomarker for the prognosis of glioma patients.
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Affiliation(s)
- Zijun Wu
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu, China
| | - Dan Wang
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu, China
| | - Fanxin Zeng
- Department of Clinic Medical Center, Dazhou Central Hospital, Dazhou, China.,Department of Radiology, School of Medicine, Stanford University, Stanford, CA, United States
| | - Yanrong Zhang
- Department of Radiology, School of Medicine, Stanford University, Stanford, CA, United States
| | - Guannan Zhu
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu, China
| | - Yiqi Ma
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu, China
| | - Bin Song
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu, China
| | - Su Lui
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu, China
| | - Min Wu
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, West China Hospital, Sichuan University, Chengdu, China.,Department of Clinic Medical Center, Dazhou Central Hospital, Dazhou, China.,Department of Radiology, School of Medicine, Stanford University, Stanford, CA, United States
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Zheng JJ, He Y, Liu Y, Li FS, Cui Z, Du XM, Wang CP, Wu YM. Novel role of PAF1 in attenuating radiosensitivity in cervical cancer by inhibiting IER5 transcription. Radiat Oncol 2020; 15:131. [PMID: 32471508 PMCID: PMC7257241 DOI: 10.1186/s13014-020-01580-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 05/20/2020] [Indexed: 01/16/2023] Open
Abstract
Background Radiosensitivity is limited in cervical cancer (CC) patients due to acquired radiation resistance. In our previous studies, we found that immediate-early response 5 (IER5) is upregulated in CC cells upon radiation exposure and decreases cell survival by promoting apoptosis. The details on the transcriptional regulation of radiation-induced IER5 expression are unknown. Studies in recent years have suggested that Pol II-associated factor 1 (PAF1) is a pivotal transcription factor for certain genes “induced” during tumor progression. In this study, we investigated the role of PAF1 in regulating IER5 expression during CC radiotherapy. Methods PAF1 expression in CC cells was measured by western blotting, immunohistochemistry, and qRT-PCR, and the localization of PAF1 and IER5 was determined by immunofluorescence. The effect of PAF1 and IER5 knockdown by siRNA in Siha and Hela cells was studied by western blotting, qRT-PCR, CCK-8 assay, and flow cytometry. The physical interaction of PAF1 with the IER5 promoter and enhancers was confirmed using chromatin immunoprecipitation and qPCR with or without enhancers knockout by CRISPR/Cas9. Results We confirmed that PAF1 was highly expressed in CC cells and that relatively low expression of IER5 was observed in cells with highly expressed PAF1 in the nucleus. PAF1 knockdown in Siha and Hela cells was associated with increased expression of IER5, reduced cell viability and higher apoptosis rate in response to radiation exposure, while simultaneous PAF1 and IER5 knockdown had little effect on the proportion of apoptotic cells. We also found that PAF1 hindered the transcription of IER5 by promoting Pol II pausing at the promoter-proximal region, which was primarily due to the binding of PAF1 at the enhancers. Conclusions PAF1 reduces CC radiosensitivity by inhibiting IER5 transcription, at least in part by regulating its enhancers. PAF1 might be a potential therapeutic target for overcoming radiation resistance in CC patients.
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Affiliation(s)
- Jing-Jie Zheng
- Department of Gynecologic Oncology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Present address: Dong-Cheng District, Qi-He-Lou Street No.17, Beijing, 100006, China
| | - Yue He
- Department of Gynecologic Oncology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Present address: Dong-Cheng District, Qi-He-Lou Street No.17, Beijing, 100006, China
| | - Yang Liu
- Department of Gynecologic Oncology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Present address: Dong-Cheng District, Qi-He-Lou Street No.17, Beijing, 100006, China
| | - Feng-Shuang Li
- Department of Gynecologic Oncology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Present address: Dong-Cheng District, Qi-He-Lou Street No.17, Beijing, 100006, China
| | - Zhen Cui
- Department of Gynecologic Oncology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Present address: Dong-Cheng District, Qi-He-Lou Street No.17, Beijing, 100006, China
| | - Xiao-Meng Du
- Department of Gynecologic Oncology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Present address: Dong-Cheng District, Qi-He-Lou Street No.17, Beijing, 100006, China
| | - Chun-Peng Wang
- Department of Gynecologic Oncology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Present address: Dong-Cheng District, Qi-He-Lou Street No.17, Beijing, 100006, China
| | - Yu-Mei Wu
- Department of Gynecologic Oncology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Present address: Dong-Cheng District, Qi-He-Lou Street No.17, Beijing, 100006, China.
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Xiong Q, Jiang X, Liu X, Zhou P, Ding K. Prediction of IER5 structure and function using a bioinformatics approach. Mol Med Rep 2019; 19:4631-4636. [PMID: 31059029 PMCID: PMC6522821 DOI: 10.3892/mmr.2019.10166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 03/25/2019] [Indexed: 11/06/2022] Open
Abstract
Immediate-early response gene 5 (IER5) is a gene involved in the regulation of the cell cycle, and its structure and function have been investigated by bioinformatics analyses. The present study determined the sites of promoter methylation and gene ontology (GO) annotations associated with IER5. In addition, we conducted a prediction analysis to determine the physical and chemical properties, hydrophobicity/hydrophilicity, posttranslational modification, subcellular localization, transmembrane structure, signal peptide and secondary and tertiary structures of IER5. One CpG island and several methylated sites were identified close to the promoter of IER5. The GO analysis suggested that IER5 could bind ions and proteins that were mainly associated with metabolic processes. IER5 comprised 327 amino acids and was reported to be an unstable hydrophilic protein with an isoelectric point of 4.91. A total of 18 O-glycosylation sites and 22 phosphorylation sites were identified within this protein. The subcellular localization of IER5 was mainly in the nucleus, and its main secondary structural element was the α-helix. Bioinformatic analyses of the features of IER5 may improve understanding of its structure and function; however, experimental verification is required.
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Affiliation(s)
- Qiang Xiong
- National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, P.R. China
| | - Xiaoyan Jiang
- National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, P.R. China
| | - Xiaodan Liu
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing 100850, P.R. China
| | - Pingkun Zhou
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing 100850, P.R. China
| | - Kuke Ding
- National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, P.R. China
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Exosome-packaged miR-1246 contributes to bystander DNA damage by targeting LIG4. Br J Cancer 2018; 119:492-502. [PMID: 30038324 PMCID: PMC6134031 DOI: 10.1038/s41416-018-0192-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 06/22/2018] [Accepted: 06/27/2018] [Indexed: 02/07/2023] Open
Abstract
Background An increasing number of studies have recently reported that
microRNAs packaged in exosomes contribute to multiple biological processes such as
cancer progression; however, little is known about their role in the development
of radiation-induced bystander effects. Methods The exosomes were isolated from the culture medium of BEP2D cells
with or without γ-ray irradiation by ultracentrifugation. To monitor DNA damage
and repair efficiency, the DNA double-strand break biomarker 53BP1 foci, comet,
micronuclei, expression of DNA repair genes and NHEJ repair activity were
detected. The miR-1246 targeting sequence of the DNA ligase 4 (LIG4) mRNA 3′UTR was assessed by luciferase reporter
vectors. Results miR-1246 was increased in exosomes secreted from 2 Gy-irradiated
BEP2D cells and inhibited the proliferation of nonirradiated cells. The miR-1246
mimic, exosomes from irradiated cells, and radiation-conditioned cell culture
medium increased the yields of 53BP1 foci, comet tail and micronuclei in
nonirradiated cells, and decreased NHEJ efficiency. miR-1246 downregulated LIG4
expression by directly targeting its 3′UTR. Conclusions Our findings demonstrate that miR-1246 packaged in exosomes could
act as a transfer messenger and contribute to DNA damage by directly repressing
the LIG4 gene. Exosomal miR-1246 may be a
critical predictor of and player in radiation-induced bystander DNA damage.
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