MiR-452 Promotes An Aggressive Colorectalcancer Phenotype By Regulating A Wnt/?-catenin Positive Feedback Loop

BackgroundColorectal cancer is one of the most common malignant tumors in China,which morbidity and mortality rank fourth among cancer in China.In recent years,the morbidity and mortality of colorectal cancer in our county have shown a significant upward trend.Metastasis can lead to recurrence and poor prognosis,which is an important factor in the death of colorectal cancer.It has not been significantly improved of the prognosis of patients with metastatic colorectal cancer,despite the emergence of new drugs and systematic treatment.Therefore,it is still an important research direction that elucidating the molecular mechanism of invasion and metastasis of colorectal cancer.MicroRNAs are a class of non-coding small RNA with a length of about 20-24 nucleotides.MiRNA binds to the 3'untranslated region of a specific RNA,leading to degradation or translation of the RNA to regulate the expression of target genes,which plays a role in promoting or inhibiting cancer.MiR-452 is a member of the mir-224/mir-452 population.In previous studies,it have confirmed that mir-224 was a carcinogenic gene in colorectal cancer.However,it is hard to known about the role of miR-452,which has been reported to be highly expressed in several malignant tumors.It is considered to be an important pathway that abnormal activation of Wnt/?-catenin signaling pathway in the progression and metastasis of colorectal cancer.It is a important markers of activation of Wnt/?-catenin signaling pathway for accumulation and nuclear translocation of P-catenin in cytoplasm.After activating Wnt signaling pathway,?-catenin escaped and degraded,and located in the nucleus to bind to TCF/LEF transcription factor family,making the downstream gene transcription of Wnt pathway.MiR-452 can activate Wnt/?-catenin signal.But the mechanism is still unclear.Therefore,the purpose of this study is to reveal the specific role of the interrelationship between miR-452 and Wnt/?-catenin pathway in colorectal cancer.Methods:1.The expression of microRNA-452 in colorectal cancer and its clinical significanceThe high expression of microRNA-452 was predicts by bioinformatics in colorectal cancer.It was used to detect the expression of microRNA-452 in 43 colorectal cancer tissues and their matched normal mucosa tissues by Real-time PCR.The expression level was positively correlated with T stage and adverse prognosis.2.Functional Study of MicroRNA-452 in Colorectal Cancer Cells in Vitro and in VitroIt were confirm that the effect of microRNA-452 on proliferation,cloning,migration and invasion of colorectal cancer cells in vitro and in vivo after the overexpression and inhibition of microRNA-452 SW480 and HCT116 cell lines that constructed plasmid transfection by MTT,plate cloning,scratch,Transwell cell invasion and subcutaneous tumorigenesis in nude mice experience.3.Screening and Identification of the Target Gene of MicroRNA-452It was confirmed the regulatory effect of microRNA-452 on the 3'-UTR of target gene GSK3? by bioinformatics and cell luciferase function studies,which led to the activation of Wnt/?-catenin signaling pathway by microRNA-452.And it was confirmed that GSK3? can effectively reverse the metastasis and invasion of microRNA-452 to colorectal cancer by a series of in vivo and in vitro experiments.4.It was confirmed that TCF4/LEF1 could up-regulate the activity of microRNA-452 promoter by Chip experiments.Results1.MiR-452 was upregulated in CRC compared with normal tissues.MiR-452 was correlated with clinical significance.2.The up-regulation of MiR-452 gene enhances the proliferation and invasion of colorectal cancer cells in vitro and in vivo.3.microRNA-452 inhibited the expression of GSK3? gene by luciferase reporting system,and it activated Wnt/p-catenin signal.the expression of GSK3P gene significantly reversed the role of MiR-452 in metastasis and proliferation of colorectal cancer.4.TCF/LEF transcription factor family is a key downstream molecule in Wnt/?-catenin signaling pathway and an effective transcription factor in the promoter of microRNA-452.ConclusionThe results emphasize the important role of miR-452 in regulating proliferation and migration in the pathogenesis of CRC with miR-452-GSK3?-TCF4/LEF1 positive feedback loop.MiR-452 may be considered as a potential prognostic marker or an effective therapeutic target for colorectal cancer.