Circulating microRNAs in gallbladder cancer: Is serum assay of diagnostic value?

The microRNAs (miRNAs) in circulation could serve as biomarkers for cancer detection. Gallbladder carcinoma (GBC) is mostly asymptomatic; therefore, using microRNAs (miRNAs) as an early diagnostic biomarker could be a valuable tool. We aimed to identify the tumor-associated miR-1, miR130, miR-146, miR-182, and miR-21expression in serum as a biomarker for early detection of GBC and identify their possible diagnostic role. The study group comprised of paired serum and tissue samples from 34 GBC, 19 cholecystitis (CC), 21 normal controls (uninflamed gall bladder), and additional 29 serum-only samples of GBC. Total RNA was isolated using a commercially available RNA isolation kit (Applied Biosystem, USA) and reverse transcribed using Advanced Taqman MicroRNA reverse transcription kit. The relative expression of miRNAs was analyzed using Quantitative real-time polymerase chain reaction. The diagnostic potential of these miRNAs was assessed by ROC analysis. In paired samples, the trend towards up and down regulation for miR-182, miR-21, miR-1, miR-130, and miR-146 was similar in both tissue and sera of GBC. The expression pattern of serum miR-1, miR130, and miR-146 gradually decreased from normal control (NC) to CC to GBC, while miR-21 and miR-182 gradually increased from NC to CC to GBC. The miR-1, miR-121, miR-182, and miR-146 significantly differed between CC vs. early stage and early stage vs. NC. Among these miRNAs, the sensitivity of miR-1 (85.71 %) was the highest, and the specificity of miR-21 was the highest (92.73 %). The combined sensitivity for miRNAs ranged from 73.13 % (CI: 60.90-83.24 %) to 98.63 % (CI: 89.0-99.61 %); however, the specificity was lower. In stage I&II vs. III&IV discrimination, the diagnostic sensitivity of miR-1 was highest (89.36 %, CI: 76.90-96.45). The two miRNAs, in combination, increase the diagnostic sensitivity. Circulating serum miRNAs may provide a new approach for clinical application. Panels of specific circulating miRNA, which require further validation, could be potential non-invasive diagnostic biomarkers for GBC in combination with abnormal radio diagnostic scans.