title: Circ100284, via miR-217 regulation of EZH2, is involved in the arsenite-accelerated cell cycle of human keratinocytes in carcinogenesis.
abstract: Circular RNAs (circRNAs), a class of noncoding RNAs generated from pre-mRNAs, participate in regulation of genes. The mechanism for regulation, however, is unknown. Here, to determine if, in human keratinocyte (HaCaT) cells, circular RNAs are involved in arsenite-induced acceleration of the cell cycle, a circRNA microarray was performed to analyze the variability of circRNAs in arsenite-treated HaCaT (As-HaCaT) cells and in arsenite-transformed (T-HaCaT) cells in comparison to control HaCaT cells. Among the circRNAs up-regulated in both As-HaCaT cells and T-HaCaT cells, hsa:circRNA_100284 (circ100284) had the greatest increase and was chosen for further research. The presence of circ100284 was confirmed in HaCaT cells. In these cells, arsenite induced increases of EZH2 and cyclin D1 and accelerated the cell cycle. MicroRNA (miR)-217 suppressed the expression of EZH2 was involved in regulation of the cell cycle. Further, in HaCaT cells exposed to arsenite, EZH2 regulated the cell cycle by binding to the promoter of CCND1, which codes for cyclin D1. Moreover, knockdown of circ100284 with siRNA inhibited the cell cycle acceleration induced by arsenite, but this inhibition was reversed by co-transfection with circ100284 siRNA and by a miR-217 inhibitor. Knockdown of circ100284 with siRNA or transfected with miR-217 mimic inhibited the capacity of T-HaCaT cells for colony formation, invasion, and migration, effects that were reversed by co-transfection with a miR-217 inhibitor or by epigenetic expression of EZH2. These results suggest that, in HaCaT cells, arsenite increases circ100284 levels, which act as a sponge for miR-217 and up-regulate the miR-217 target, EZH2, which, in turn, up-regulates cyclin D1and CDK4, and thus accelerates the cell cycle and leads to malignant transformation. Thus, circ100284, via miR-217 regulation of EZH2, is involved in the arsenite-accelerated cell cycle of human keratinocytes in carcinogenesis. This establishes a previously unknown mechanism between arsenite-induced acceleration of the cell cycle and carcinogenesis.
authors.affiliation: Institute of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China; The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China.
authors.forename: Junchao
authors.initials: J
authors.lastname: Xue
authors.affiliation: Department of Orthopaedics, the First Clinic Medical College, Nanjing Medical University, Nanjing 210011, Jiangsu, People's Republic of China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Institute of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China; The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Luo
authors.affiliation: Institute of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China; The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Lu
authors.affiliation: Institute of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China; The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.affiliation: Institute of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China; The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China.
authors.forename: Xinlu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Institute of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China; The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China.
authors.forename: Lu
authors.initials: L
authors.lastname: Lu
authors.affiliation: Institute of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China; The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China.
authors.forename: Qianlei
authors.initials: Q
authors.lastname: Yang
authors.affiliation: Institute of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China; The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Orthopaedics, the First Clinic Medical College, Nanjing Medical University, Nanjing 210011, Jiangsu, People's Republic of China.
authors.forename: Weimin
authors.initials: W
authors.lastname: Fan
authors.affiliation: Institute of Toxicology, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China; The Key Laboratory of Modern Toxicology, Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, Jiangsu, People's Republic of China. Electronic address: drqzliu@hotmail.com.
authors.forename: Qizhan
authors.initials: Q
authors.lastname: Liu
mesh_terms: D018053:Arsenites / Q000009:adverse effects*; D063646:Carcinogenesis / Q000139:chemically induced* / Q000235:genetics* / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D000071221:Enhancer of Zeste Homolog 2 Protein / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000473:pathology; D035683:MicroRNAs / Q000235:genetics*; D012313:RNA / Q000235:genetics*; D000079962:RNA, Circular
chemical_list: D018053:Arsenites; C553315:MIRN217 microRNA, human; D035683:MicroRNAs; D000079962:RNA, Circular; D012313:RNA; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; C015001:arsenite
keywords: Arsenite; Carcinogenesis; Cell cycle; circRNAs; miRNAs