MicroRNA-194 is a Marker for Good Prognosis in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most prevalent adult kidney cancer. Prognostic markers are needed to guide patient management toward aggressive versus more conservative approaches, especially for small tumors ≤4 cm. miR-194 was reported to be downregulated in several cancers and is involved in epithelial to mesenchymal transition. We evaluated miR-194 as a prognostic marker in ccRCC. In a cohort of 234 patients with primary ccRCC, we correlated miR-194 expression level with multiple clinicopathological features including disease-free and overall survival, tumor size, clinical stage, and histological grade. Our results shows a stepwise decrease in miR-194 expression from normal kidney to primary ccRCC (P = 0.0032) and a subsequent decrease from primary to metastatic lesions. Additionally, patients with higher miR-194 expression has significantly longer disease-free survival (P = 0.041) and overall survival (P = 0.031) compared to those with lower expression. In multivariate analysis, miR-194-positive tumors retain significance in disease-free survival and overall survival, suggesting miR-194 is an independent marker for good prognosis in ccRCC. Moreover, miR-194 is a marker for good prognosis for patients with small renal masses (P = 0.014). These findings were validated on an independent data set from The Cancer Genome Atlas. We also compared miR-194 expression between RCC subtypes. ccRCC had the highest levels, whereas chromophobe RCC and oncocytoma had comparable lower levels. Target prediction coupled with pathway analysis show that miR-194 is predicted to target key molecules and pathways involved in RCC progression. miR-194 represents a prognostic biomarker in ccRCC.