Serum miR-210 as a potential biomarker of early clear cell renal cell carcinoma

Early detection and treatment are critical in the management of renal cell carcinoma (RCC). However, there is no standard serum biomarker to facilitate early diagnosis or prognostic stratification in patients with RCC. Recent reports suggest that circulating microRNAs (miRNAs) have great potential as biomarkers for diagnosis and prognosis in patients with several types of cancers. Further, many studies using miRNA microarray analysis demonstrated that miR-210 expression in clear cell carcinoma (CCC), which is the largest subtype of RCC, was significantly upregulated in tumor tissue. Therefore, we investigated whether serum miR-210 could be a useful biomarker for the diagnosis and progression of CCC. This study included 34 CCC patients and 23 healthy controls (HC). First, we analyzed tissue miR-210 levels in tumor tissues and matched normal tissues from the 34 CCC patients. Second, we investigated the serum miR-210 levels in the 34 CCC patients and the 23 HC patients. Real-time polymerase chain reaction (PCR) was used to measure miRNA levels. Moreover, we examined the correlation between serum miR-210 levels and the clinicopathological parameters. Among patients with CCC, expression of miR-210 was higher in tumor tissues compared to normal tissues (P<0.001). Serum miR-210 levels were higher in CCC patients compared to HCs (P=0.001). Receiver operating characteristic (ROC) curve analysis showed an area under the ROC curve (AUC) of 0.77 (95% confidence interval, 0.65-0.89) and a sensitivity and specificity of 65 and 83%, respectively. In addition, there was no significant association between serum miR-210 levels and age, sex, tumor size or existence of metastasis at diagnosis among the 34 CCC patients. In conclusion, serum miR-210 upregulation may occur in the early stage of CCC and serum miR-210 can be a useful biomarker for early CCC in humans.