The Role And Mechanism Of MiRNA-122 In Clear Cell Renal Cell Carcinoma

Objective:Renal clear cell carcinoma(ccRCC)is the main pathological type of renal cell carcinoma,accounting for 60%to 85%of them.MicroRNA plays an important role in the development of ccRCC,but its mechanism of action is still not completely clear.We conducted a comprehensive analysis of the ccRCC expression data in the GEO database and screened key miRNA molecules that regulate ccRCC.Studies have shown that microRNA-122(miR-122)is dysregulated in many cancers,yet its role in ccRCC remains unclear.Methods:?We analyzed and screened differentially expressed miRNAs in four ccRCC miRNA tissue microarrays from GEO database,and validated the prognostic value of the differentially expressed miRNAs in TCGA database and screened the key miRNAs related to prognosis.? The expression of miR-122 was verified in the tissues and cell lines of ccRCC,and combined with clinical prognostic value analysis.?We transfected miR-122 mimics or inhibitors in ccRCC lines.The results of cell proliferation,colony formation,migration and invasion were measured in vitro.? We use bioinformatics methods to predict miR-122 target genes,and use luciferase reporter assays,Western blots,and immunofluorescence assays to verify the binding of miR-122 to target genes.? Co-transfection of miR-122 with FOXO3 in ccRCC lines to verify whether FOXO3 can reverse the oncogenic effects of miR-122.?The nude mouse subcutaneous tumorigenesis model was used to study the oncogenic effects of miR-122 in vivo.RESULTS:?The integrated analysis of chips showed that miR-122 was highly expressed in the four ccRCC miRNA expression data and was associated with a poor prognosis.?The expression level of miR-122 was significantly increased in clinical specimens and cell lines of ccRCC,and negatively correlated with patients' survival time without metastasis.?Over-expression of miR-122 in 786-O cell line accelerated cell proliferation and colony formation,and enhanced cell migration and invasion;knocking down miR-122 in SN12-PM6 cells inhibited cell growth and the formation of colonies and weakened cell migration and invasion.?Through bioinformatics methods,luciferase reporter assays,Western blotting and immunofluorescence experiments,it was screened and verified that FOXO3 is a direct target of miR-122.?FOXO3 can reverse the oncogenic effects of miR-122 in ccRCC cell lines.?MiR-122 can reduce FOXO3 protein expression of ccRCC and accelerate tumor growth in mice.CONCLUSIONS:?Increased expression of miR-122 may be associated with poor prognosis of ccRCC.?MiR-122 can exert tumorigenic effects through targeted inhibition of FOXO3 protein expression.