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Jun-Qian Huang,1 Fang Wang,2 Long-Tao Wang,3 Yong-Mei Li,4 Jun-Li Lu,5 Jian-You Chen2 1Department of Respiratory and Critical Medicine, Qingdao Chengyang District People’s Hospital, Qingdao, Shandong, People’s Republic of China; 2Department of Respiratory Medicine, Qingdao Municipal Hospital, Qingdao, Shandong, People’s Republic of China; 3Department of Critical Care Medicine, Qingdao Chengyang District People’s Hospital, Qingdao, Shandong, People’s Republic of China; 4Department of Clinical Pharmacy, Qingdao Chengyang District People’s Hospital, Qingdao, Shandong, People’s Republic of China; 5Qingdao Chengyang District People’s Hospital, Qingdao, Shandong, People’s Republic of ChinaCorrespondence: Jian-You ChenDepartment of Respiratory Medicine, Qingdao Municipal Hospital, Qingdao, Shandong, People’s Republic of ChinaEmail youchanmou9834@163.comBackground: Asthma belongs to chronic inflammatory respiratory diseases characterized by airway inflammation and remodeling. Circular RNAs (circRNAs) are promising therapeutic targets for various diseases, including asthma. In this work, we aim to investigate the role of circular RNA Erb-B2 receptor tyrosine kinase 2 (circERBB2) during progression of asthma.Methods: Human airway smooth muscle cells (ASMCs) were treated with platelet-derived growth factor BB (PDGF-BB) to mimic cell remodeling. The expression of circERBB2, microRNA-98-5p (miR-98-5p), and insulin-like growth factor 1 receptor (IGF1R) was measured by qRT-PCR. Cell proliferation, migration and apoptosis were determined by cell counting-8 (CCK-8), transwell, and flow cytometry. Protein levels of PCNA, MMP-9, IGF1R were evaluated using Western blotting. The levels of tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), and IL‐6 were detected by enzyme‐linked immunosorbent assay (ELISA). Luciferase reporter gene experiment was adopted to evaluate the targeting relationship between miR-98-5p with circERBB2 and IGF1R. Interaction between RNAs was determined by RNA pulldown and RIP assay.Results: The depletion of circERBB2 attenuated the proliferation, migration, and levels of inflammatory factors induced by PDGF-BB and cell apoptosis. CircERBB2 was identified to directly interact with miR-98-5p, and overexpression of miR-98-5p abolished the function of circERBB2 on PDGF-BB-stimulated ASMCs. IGF1R was identified as a target of miR-98-5p, and knockdown of IGF1R relieved the PDGF-BB-induced ASMCs proliferation and migration.Conclusion: Our work disclosed that knockdown of circERBB2 suppressed PDGF-BB-caused proliferation, migration and inflammatory response of ASMCs, through regulating miR-98-5p/IGF1R signaling, presented circERBB2 as a promising therapeutic target for asthma.Keywords: asthma, circERBB2, miR-98-5p, IGF1R, proliferation, migration

Background CircRNAs are found to affect initiation and progression of several cancer types. However, whether circRNAs are implicated in gallbladder cancer (GBC) progression remains obscure. Methods We perform RNA sequencing in 10 pairs of GBC and para-cancer tissues. CCK8 and clone formation assays are used to evaluate proliferation ability of GBC cells. qPCR and Western blot are used to determine expression of RNAs and proteins, respectively. CircRNA-protein interaction is confirmed by RNA pulldown, RNA immunoprecipitation, and fluorescence in situ hybridization. Results We find that circRNA expression pattern is tremendously changed during GBC development. Among dozens of significantly changed circRNAs, a circRNA generated from the oncogene ERBB2, named as circERBB2, is one of the most significant changes. CircERBB2 promotes GBC proliferation, in vitro and in vivo. Other than being a miRNA sponge, circERBB2 accumulates in the nucleoli and regulates ribosomal DNA transcription, which is one of the rate-limiting steps of ribosome synthesis and cellular proliferation. CircERBB2 regulates nucleolar localization of PA2G4, thereby forming a circERBB2-PA2G4-TIFIA regulatory axis to modulate ribosomal DNA transcription and GBC proliferation. Increased expression of circERBB2 is associated with worse prognosis of GBC patients. Conclusions Our findings demonstrate that circERBB2 serves as an important regulator of cancer cell proliferation and shows the potential to be a new therapeutic target of GBC.