title: Overexpression of miR-18a negatively regulates myocyte enhancer factor 2D to increase the permeability of the blood-tumor barrier via Krüppel-like factor 4-mediated downregulation of zonula occluden-1, claudin-5, and occludin.
abstract: miR-18a represses angiogenesis and tumor evasion by weakening vascular endothelial growth factor and transforming growth factor-β signaling to prolong the survival of glioma patients, although it is thought to be an oncogene. This study investigates the potential effects of miR-18a on the permeability of the blood-tumor barrier (BTB) and its possible molecular mechanisms. An in vitro BTB model was successfully established. The endogenous expression of miR-18a in glioma vascular endothelial cells (GECs) was significantly lower than that in normal vascular ECs, and the overexpression of miR-18a significantly increased the permeability of the BTB as well as downregulating the mRNA and protein expressions of tight junction-related proteins zonula occluden-1 (ZO-1), claudin-5, and occludin in GECs. Dual luciferase reporter assays revealed that miR-18a bound to the 3'-untranslated region (3'UTR) of myocyte enhancer factor 2D (MEF2D). The overexpression of both miR-18a and MEF2D with the 3'UTR significantly weakened the effect caused by miR-18a of decreasing the mRNA and protein expressions of ZO-1, claudin-5 and occludin and of increasing the permeability of the BTB. Chromatin immunoprecipitation showed that MEF2D could directly bind to KLF4 promoter. This study shows that miR-18a targets and negatively regulates MEF2D, which further regulates tight junction-related proteins ZO-1, claudin-5, and occludin through transactivation of KLF4 and, finally, changes the permeability of the BTB. MiR-18a should garner growing attention because it might serve as a potential target in opening the BTB and providing a new strategy for the treatment of gliomas.
authors.affiliation: Department of Neurobiology, College of Basic Medicine, China Medical University, Shenyang, China.|Institute of Pathology and Pathophysiology, China Medical University, Shenyang, China.
authors.forename: Ying-Yu
authors.initials: YY
authors.lastname: Zhao
authors.affiliation: Department of Neurobiology, College of Basic Medicine, China Medical University, Shenyang, China.|Institute of Pathology and Pathophysiology, China Medical University, Shenyang, China.
authors.forename: Li-Ni
authors.initials: LN
authors.lastname: Zhao
authors.affiliation: Department of Neurobiology, College of Basic Medicine, China Medical University, Shenyang, China.|Institute of Pathology and Pathophysiology, China Medical University, Shenyang, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Neurobiology, College of Basic Medicine, China Medical University, Shenyang, China.|Institute of Pathology and Pathophysiology, China Medical University, Shenyang, China.
authors.forename: Yin-Sha
authors.initials: YS
authors.lastname: Miao
authors.affiliation: Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang, China.
authors.forename: Yun-Hui
authors.initials: YH
authors.lastname: Liu
authors.affiliation: Department of Physiology, College of Basic Medicine, China Medical University, Shenyang, China.
authors.forename: Zhen-Hua
authors.initials: ZH
authors.lastname: Wang
authors.affiliation: Department of Neurobiology, College of Basic Medicine, China Medical University, Shenyang, China.|Institute of Pathology and Pathophysiology, China Medical University, Shenyang, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Neurobiology, College of Basic Medicine, China Medical University, Shenyang, China.|Institute of Pathology and Pathophysiology, China Medical University, Shenyang, China.
authors.forename: Zhi-Qing
authors.initials: ZQ
authors.lastname: Li
authors.affiliation: Department of Neurobiology, College of Basic Medicine, China Medical University, Shenyang, China.|Institute of Pathology and Pathophysiology, China Medical University, Shenyang, China.
authors.forename: Yi-Xue
authors.initials: YX
authors.lastname: Xue
mesh_terms: D001812:Blood-Brain Barrier / Q000166:cytology; D002199:Capillary Permeability / Q000502:physiology; D002461:Cell Line, Transformed; D047369:Chromatin Immunoprecipitation; D062507:Claudin-5 / Q000378:metabolism; D015536:Down-Regulation / Q000502:physiology*; D004847:Epithelial Cells / Q000378:metabolism*; D005910:Glioma / Q000473:pathology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism*; D064326:MEF2 Transcription Factors / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D062793:Occludin / Q000378:metabolism; D010539:Permeability; D012333:RNA, Messenger / Q000378:metabolism; D014162:Transfection; D062825:Zonula Occludens Proteins / Q000235:genetics / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein / Q000378:metabolism
chemical_list: D062507:Claudin-5; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D064326:MEF2 Transcription Factors; C522576:MIRN18A microRNA, human; D035683:MicroRNAs; D062793:Occludin; D012333:RNA, Messenger; D062825:Zonula Occludens Proteins; D062826:Zonula Occludens-1 Protein; D049452:Green Fluorescent Proteins; D006735:Horseradish Peroxidase
keywords: AB_10375873; AB_10835246; AB_10836283; AB_10836645; AB_1310389; AB_398095; KLF4; MEF2D; OMICS_00420; blood-tumor barrier; miR-18a; nif-0000-02738; tight junction-related proteins