Comprehensive Circular RNA Expression Profiles And The Function And Mechanism Of CircHIPK3 In Ovarian Cancer

Background With the development of high-throughput sequencing?HTS?,thousands of circular RNAs?circRNAs?have been found.Many circRNAs have been verified to play vital roles in carcinogenesis.However,whether circRNAs engage in the development and progression of ovarian cancer remains to be clarified.Methods We analyzed circRNA expression profiling in epithelial ovarian cancer?EOC?and normal ovarian tissues?NOT?using HTS and validated six randomly selected circRNAs via quantitative real-time-PCR?qRT-PCR?,Sanger sequencing after RNase treatment and reverse-transcription PCR?RT-PCR?.CircHIPK3,the most abundant circRNA in our sequencing data,was further knocked down by siRNA.The circHIPK3 function in migration,invasion,proliferation and apoptosis of A2780 and SKOV3 ovarian cancer cells was analyzed via wound healing,transwell,cell counting-kit 8?CCK8?and flow cytometry analysis after circHIPK3 was efficiently silenced.Results Altogether,we found 7333 circRNAs,of which 4505?61.43%?were newly identified,2431 were significantly upregulated and 3120 were remarkably downregulated.Six randomly selected differentially expressed circRNAs were examined in 18 EOC and 18 NOT.circHIPK3?hsa_circ₀000284?,circRHOBTB3?hsa_circ₀007444?,circPCMTD1?hsa_circ₀001801?,circSETD3?hsa_circ₀000567?and circATRNL1?hsa_circ₀020093?were significantly decreased,whereas that of circAC139769.1,a newly found circRNA,was dramatically increased in the EOC group.Furthermore,the results of RT-PCR and Sanger sequencing after RNase treatment confirmed circular back-splicing.Silencing of circHIPK3 promoted migration,invasion,proliferation of A2780 and SKOV3 ovarian cancer cells and inhibited apoptosis of SKOV3 cells.Additionally,the circHIPK3-miRNA-mRNA axis was predicted as the possible mechanism using bioinformatic approaches.Conclusion We identified the circRNA expression profile in ovarian cancer tissues and further verified the existence and expression of six randomly selected differentially expressed circRNAs.The most abundant circRNA,circHIPK3,was chosen to be downregulated.Knock-down of circHIPK3 promoted the malignant behavior of ovarian cance cells.Through bioinformatic analysis,we predicted that circHIPK3 might effect by the mechanism of ceRNA?competing endogenous RNA,ceRNA?.Thus,we concluded that circHIPK3 is an important regulator of ovarian cancer progression.