title: A double-negative feedback loop between EZH2 and miR-26a regulates tumor cell growth in hepatocellular carcinoma.
abstract: Accumulating evidence demonstrates the important roles of microRNAs (miRNAs) in tumor development and progression. miR-26a has been reported to be downregulated in several types of cancers including hepatocellular carcinoma, but the underlying mechanism of how miR-26a is repressed remains largely unknown. In the present study, we performed western blot analysis, qRT-PCR, luciferase reporter assay and chromatin immunoprecipitation assay to investigate the relationship between miR-26a and the enhancer of zest homologue 2 (EZH2). CCK-8 assay and colony formation assay were carried out to explore the effect of miR-26a on HCC cells proliferation. We demonstrated that miR-26a was epigenetically repressed by EZH2-mediated H3K27 trimethylation within the miR-26a promoter. Moreover, we confirmed that EZH2 was also a direct target of miR-26a in HCC cells, thus, creating a double-negative feedback loop. Furthermore, miR-26a restoration increased the expressions of its host genes (CTDSPL and CTDSP2). Overexpression of EZH2 abrogated miR-26a induction of CTDSPL and CTDSP2. Restoring the balance of the double-negative feedback loop by miR-26a overpression or EZH2 silence significantly inhibited HCC cell growth. Overexpression of EZH2 rescued the growth inhibition effect of miR-26a. These findings suggest that an imbalanced double-negative feedback loop between EZH2 and miR-26a exists in HCC cells, which contributes to miR-26a deregulation and regulates tumor cells proliferation.
authors.affiliation: Department of Clinical Laboratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China.
authors.forename: Chunbo
authors.initials: C
authors.lastname: Zhuang
authors.affiliation: Department of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China.
authors.forename: Pei
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Clinical Laboratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China.
authors.forename: Da
authors.initials: D
authors.lastname: Huang
authors.affiliation: Regenerative Medicine Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China.
authors.forename: Luming
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Clinical Laboratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China.
authors.forename: Xiaobei
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Clinical Laboratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Clinical Laboratory Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Hu
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015536:Down-Regulation; D000071221:Enhancer of Zeste Homolog 2 Protein; D044127:Epigenesis, Genetic; D025461:Feedback, Physiological; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism*; D035683:MicroRNAs / Q000378:metabolism*; D010957:Plasmids / Q000737:chemistry; D063151:Polycomb Repressive Complex 2 / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D000071221:Enhancer of Zeste Homolog 2 Protein; D035683:MicroRNAs; D063151:Polycomb Repressive Complex 2; C528163:MIRN26 microRNA, human; C498409:EZH2 protein, human