Exploration Of The Expression And Function Of MiR-660-5p In Renal Cell Carcinoma

Objective:Renal cell carcinoma(RCC)is a common malignant tumor of the urinary system with poor prognosis.microRNAs(miRNAs)are a class of small,non-coding RNA molecules that serve important roles in biological and pathological processes in several types of human tumors.Previous studies have revealed that miRNA(miR)-660-5p expression is dysregulated in many human malignancies,such as lung cancer,breast cancer,multiple myeloma and chronic lymphocytic leukemia.However,its role in renal cell carcinoma is currently unclear.The aim of this study was to investigate the expression and function of miR-660-5p in renal cell carcinoma and to analyze the possibility of using miR-660-5p as a biomarker of renal cell carcinoma.Methods:According to the results of four previous microarray chip studies which have demonstrated that miR-660-5p was downregulated in RCC,we choose miR-660-5p for further examination.Reverse transcription-quantitative polymerase chain reaction(RT-qPCR)was performed to examine the expression levels of miR-660-5p in RCC tissues and paired normal adjacent tissues(NATs).The relationship between expression levels of miR-660-5p and clinicopathological features of renal cell carcinoma patients was explored by?~2 test.Expression of miR-660-5p was up-regulated or down-regulated with transfecting miR-660-5p inhibitor or mimic.To determine the function of miR-660-5p in RCC cells,Wound-healing and Transwell assays were performed to determine the effects of miR-660-5p on cell migration and invasion,respectively.MTT and Cell Counting kit-8 assays were performed to determine the effects of miR-660-5p on RCC cell proliferation.In addition,flow cytometric analysis was performed to validate the effects of miR-660-5p on apoptosis.Results:RT-qPCR demonstrated that the expression of miR-660-5p in RCC tissues(mean relative expression,3.44±0.375)was lower than in the NATs(P<0.01).miR-660-5p expression levels in the 786-O and ACHN cells transfected with miR-660-5p inhibitors were 0.13±0.029 and 0.01±0.00309,respectively,whereas expression in cells transfected with miR-660-5p mimic was 1762.10±261.812 and 590.19±112.202,respectively(P<0.05).As for the function of miR-660-5p in RCC,wound-healing assays revealed that overexpression of miR-660-5p can suppress cell migration.Transwell assays showed that overexpression of miR-660-5p can inhibit cell migration.MTT and CCK-8 assays revealed that overexpression of miR-660-5p can suppress cell proliferation in RCC.And flow cytometric analysis demonstrated that downregulation of miR-660-5p can induce cell apoptosis.Conclusion:miR?660?5p expression is downregulated in RCC tissues compared with NATs.Restoration of miR-660-5p expression using synthetic mimics may suppress cell migration,invasion and proliferation,and induce cell apoptosis,while using synthetic inhibitors may promote cell migration,invasion and proliferation,and suppress cell apoptosis.These results suggested that miR-660-5p may serve a tumor suppressive role in RCC tumorigenesis and have a potential value in clinical practice,such as tumor markers for diagnosis,prognosis and possibly novel treatments.