Hsa＿circ＿0009061 Inhibits The Progression Of Bladder Cancer Through The MiR-889-3p/CPEB3 Axis

Background: Bladder cancer（BCa）,which is a common tumor of the urinary system,is mainly characterized by high risk of recurrence,high risk of metastasis and high risk of death.At present,the etiology and pathogenesis of bladder cancer is still unclear and remain to be elucidated.Although surgery,radiotherapy,chemotherapy and immunotherapy have partly improved the prognosis of patients with bladder cancer,they still cannot achieve satisfactory effects.Therefore,it is necessary to explore the molecular mechanism of malignant progression of bladder cancer,because the research may find reliable biomarkers for early diagnosis and outcome prediction,and may provide new directions for targeted therapy.Circular RNA is a special RNA,which presents a single-stranded,covalently closed circular structure without 5’methylguanosine cap and 3’ polyadenylic acid tail.The circular RNA has become a hotspot in the field of RNA research for its unique structure,generation,regulation,degradation in recent years.In bladder cancer,circular RNAs are not only significantly correlated with the clinicopathological feature,but also involved in multiple biological behaviors.Furthermore,some exosomal circular RNAs can also be used as biomarkers for early diagnosis and prognosis evaluation of bladder cancer for its high stability.In conclusion,circular RNA play an important role in the occurrence,malignant progression,diagnosis and prognosis evaluation of bladder cancer,suggesting that circular RNA have the potential to be therapeutic targets in bladder cancer.Methods: This study applied bioinformatics methods to preliminarily screened the differentially expressed circular RNAs between bladder cancer and corresponding adjacent tissue.Real-time quantitative PCR（RT-qPCR）experiments were performed to identify differentially expressed circular RNAs in cell lines and tissues of bladder cancer.The functional experiments including plate cloning,CCK-8,Edu and xenograft tumor models were implemented to investigate the biological behavior changes of bladder cancer induced by knocking down hsa＿circ＿0009061 in vitro and in vivo.Bioinformatics methods were applied to predict miRNAs that circular RNA might bind to and the miRNA target genes,and the real-time quantitative PCR,RNA pulldown,dual luciferase reporter experiment and western blot were utilized to explore the mechanism of hsa＿circ＿0009061 regulating bladder cancer progression.Results: The bioinformatics analysis and RT-qPCR find that hsa＿circ＿0009061 was downregulated in cell lines and tissues of bladder cancer.After successfully knocking down hsa＿circ＿0009061 in bladder tumor cells,functional experiments including plate cloning,Edu and CCK-8 revealed that silencing hsa＿circ＿0009061 could promote the malignant proliferation of bladder tumor cell lines in vitro.Xenograft tumor model also verified that silencing hsa＿circ＿0009061 could promote tumor formation in vivo.Mechanistic studies have shown that hsa＿circ＿0009061 can act as a competitive endogenous RNA to bind to hsa-miR-889-3p and regulate the expression of CPEB3,resulting in the malignant progression of bladder cancer.Conclusion: This study found that hsa＿circ＿0009061 was downregulated in cell lines and tumor specimens of bladder cancer and could affect the progression of bladder cancer.Mechanistically,hsa＿circ＿0009061 can bind to hsa-miR-889-3p to regulate the expression of CPEB3,suggesting that hsa＿circ＿0009061 may be a new treatment option for bladder cancer.