Expression of microRNAs in the ascites of patients with peritoneal carcinomatosis and peritonitis

Background Peritoneal carcinomatosis (PCA) has a prognostic role in patients with gastrointestinal cancers. The differential diagnosis may be challenging due to the low sensitivity of cytology. Although microRNAs (miRNAs) have been a focus of various specimens and diseases, to the best of the authors' knowledge only limited knowledge exists regarding ascites. Herein, the authors systematically evaluated preanalytical factors and the potential of miRNAs as biomarkers of ascites. Methods The authors prospectively analyzed samples from patients with PCA, spontaneous bacterial peritonitis (SBP), and portal hypertension (no SBP/PCA). Various preanalytical factors such as extraction kits, sample storage, stability, and processing were systematically evaluated. MiRNA expression profiling using TaqMan Low Density Array and quantitative reverse transcriptase-polymerase chain reaction were used to evaluate miRNA expression. Results All selected miRNAs were found to be reliably detectable in ascites samples. Ascites miRNAs were well preserved from degradation with required short-term and long-term stability. MiRNA expression profiling in patients with PCA compared with those with no SBP/PCA revealed miR-21, miR-186, miR-222, and miR-483-5p to be upregulated and miR-26b to be downregulated. MiRNA expression validation analysis confirmed higher expression levels of miR-21 and miR-186 in patients with PCA compared with those with no SBP/PCA, whereas miR-223 was significantly upregulated in patients with SBP. A simple proportion score between miR-21 and miR-223 allowed the authors to discriminate between the patients with PCA and those with SBP with an area under the curve of 0.982 (95% confidence interval, 0.943-1.022). Conclusions The data from the current study provide novel evidence of the differential expression of miRNAs in ascites from patients with PCA and SBP, which may offer an additional miRNA-based molecular approach for the differential diagnosis of PCA. Cancer Cytopathol 2018;126:353-63. © 2018 American Cancer Society.