Pattern of Expression of MicroRNA in Patients with Radiation-Induced Bladder Injury

Abstract

Introduction: Bladder cancer (BC) is sensitive to radiation treatment and a subset of patient experiences radiation induced injuries including shrinkage of bladder due to bladder fibrosis. Methods: Using a micro-RNA (miRNA) array comparing patient’s samples with, or without radiation induced injuries, we have checked the clustering of miRNA expression. Results: Hsa-miR-130a, hsa-miR-200c, hsa-miR-141, and hsa-miR-96 were found to be highly expressed (>50 times) in patients with fibrotic bladder shrinkage (FBS) compared to those with intact bladder (IB) function. In patients with FBS, hsa-miR-6835, hsa-miR-4675, hsa-miR-371a, and hsa-miR-6885 were detected to have lesser than half expression to IB patients. We have analyzed the significance of these genes in relation to overall survival of 409 BC patients retrieved from TCGA data set. We have run combined survival analysis of mean expression of these four miRNAs highly expressed in FBS patients. 175 patients with high expression had longer median survival of 98.47 months than 23.73 months in 233 patients with low expression (HR: 0.53; 0.39 – 0.72, logrank P value: 7.3e-0.5). Combination analysis of all 8 genes including hsa-miR-6835, hsa-miR-4675, hsa-miR-371a, and hsa-miR-6885 showed the same HR for OS. Target scanning for these miRNAs matched specific cytokines known as an early biomarker to develop radiation induced fibrosis. Conclusions: BC patients with fibrotic radiation injury have specific miRNA expression profile targeting pro-fibrotic cytokines and these miRNAs possibly renders to favorable survival.