Identification of miR-18a-5p as an oncogene and prognostic biomarker in RCC

Background: RCC is a malignant tumor that originates from renal tubular epithelial cells, accounting for nearly 90% of renal malignancies and 3% of adult malignancies. It was reported that more than 30-40% of patients with early localized RCC still have recurrence and metastasis after receiving radical surgery. miRNAs are an endogenous non-coding small RNAs that play an important role in the regulation of tumor cell proliferation, differentiation and apoptosis. Methods: In our study, RT-qPCR, CCK-8 assay, wound scratch assay, transwell assay and flow cytometry assay were designed to identify the expression and functions of miR-18a-5p in RCC. Moreover, we collected the survival data from The Cancer Genome Atlas to predict and clarify the prognostic functions of miR-18a-5p in RCC. The correlation between miR-18a-5p expression and clinicopathological variables or overall survival was analyzed by 42 formalin-fixed paraffin-embedded (FFPE) renal cancer samples. Results: The expression of miR-18a-5p in RCC tissues and cell lines was elevated. Further researches suggested that upregulation of miR-18a-5p had a positive effect on RCC cell proliferation, migration, invasion and inhibition of apoptosis, while down-regulation of miR-18a-5p neutralized the effect. In addition, Data of TCGA and prognostic analysis of FFPE RCC samples revealed that high miR-18a-5p expression patients had significantly poorer survival. Conclusions: These results demonstrated that miR-18a-5p functioned as an oncogene and prognostic biomarker in RCC.