Identification and study of regulatory axis that miRNA-224-5p targets NEDD4L gene in clear cell renal cell carcinoma / 肿瘤研究与临床

ABSTRACT

Objective:To screen key genes of renal clear cell carcinoma based on bioinformatics methods, identify possible microRNA (miRNA)-mRNA action axis, and explore the expression of related genes in clear cell renal cell carcinoma tissues and cells.Methods:Gene expression profiles of GSE40435 and GSE71302 datasets were obtained from the Gene Expression Omnibus (GEO) database. TCGA-KIRC datasets were obtained from The Cancer Genome Atlas (TCGA) database. R software was used to identify the differentially expressed mRNA and miRNA, and the functional enrichment analysis was performed. STRING database and Cytoscape software were used to perform the protein interaction analysis. The prognosis-related differentially expressed miRNA was evaluated by the Oncomir database. The potential targeted genes regulated by miRNA were determined by using TargetScan and miRDB targeted gene prediction tools. The tissue samples and clinicopathological features of 34 patients with clear cell renal cell carcinoma in the First Hospital of Shanxi Medical University from June to December 2021 were collected, and normal renal cell line 293T and clear cell renal cell carcinoma cell line 786O were selected. The real-time fluorescence quantitative polymerase chain reaction (qRT-PCR), was used to detect the relative expression of genes; Western blotting and immunohistochemical staining were used to detect the expression levels of the targeted proteins. The dual luciferase reporter gene assay was carried out to verify the targeting relationship between genes.Results:A total of 1 351 differentially expressed mRNA and 50 differentially expressed miRNA were screened and identified. The result of functional enrichment analysis suggested that the fatty acid metabolism pathway and xenobiotic metabolism pathway were suppressed in clear cell renal cell carcinoma, while the apoptosis and immune response pathways were activated. Protein interaction analysis suggested that the signal transduction and protein ubiquitination pathways might play a key role in clear cell renal cell carcinoma. The screening results showed that miRNA-224-5p (miR-224-5p) was most closely associated with clear cell renal cell carcinoma progression and was highly expressed in tumor tissues, and its prognosis-related target gene was NEDD4L. The relative expression of NEDD4L mRNA in clear cell renal cell carcinoma tissues and paraneoplastic tissues were 0.138±0.103 and 1.000±0.026 ( t = 46.23, P < 0.05), and the relative expression of miR-224-5p was 1.000±0.043 and 0.129±0.108 ( t = 45.28, P < 0.05). The differences of NEDD4L mRNA and miR-224-5p expressions in different grades and stages of clear cell renal cell carcinoma tissues were statistically significant (all P < 0.05). The expression of NEDD4L protein was decreased in clear cell renal cell carcinoma. The relative expression of NEDD4L gene in 293T and 786O cells were 1.000±0.125 and 0.210±0.044 ( t = 17.52, P < 0.05); the relative expressions of miR-224-5p gene were 0.209±0.049 and 1.000±0.234 ( t = 10.61, P < 0.05). The relative expressions of NEDD4L mRNA in miRNA mimic group and negative control group were 0.236±0.062 and 1.000±0.024, and the difference was statistically significant ( t = 43.56, P < 0.05). NEDD4L protein expression was reduced in the miRNA mimic group. Dual luciferase reporter gene assay suggested that NEDD4L was a direct target gene of miR-224-5p. Conclusions:In clear cell renal cell carcinoma, miR-224-5p targets and regulates NEDD4L expression, and this mechanism may be related to carcinogenesis and progression of clear cell renal cell carcinoma.