Exosomal onco-miRs from serum of patients with adenocarcinoma of the esophagus: comparison of miRNA profiles of exosomes and matching tumor.

Diagnostic markers are needed for achieving a cure in esophageal cancer, detecting tumor cells earlier. Exosomes are bioactive vesicles secreted by cells into surrounding body fluids. Exosome formation, cargo content, and delivery have major impact in cancer development. This is the first isolation of exosomes from serum of patients with adenocarcinoma of the esophagus and comparison of exosomal miRNA profiles with matching primary tumor and normal tissues. RNA was extracted for miRNA profiling by real-time TaqMan miR arrays. The miR profiles of exosomal cargo, matching tumor, and normal tissue of a subgroup of adenocarcinoma patients have been compared. "Exosomal onco-miRs" such as miR-223-5p, miR-223-3p, miR-483-5p, miR-409-3p, miR-196b-5p, miR-192-5p, miR-146a-5p, and miR-126-5p have been identified as part of exosomal cargo being overexpressed in corresponding tumor compared to normal. Upregulation of miR-223-5p and miR-483-5p in adenocarcinoma (p = 0.034, p = 0.017) has been verified by an independent cohort of 43 patients with T2-3 adeno- and squamous cell carcinoma. In contrast, miR-224-5p, miR-452-5p, miR-23b-5p, miR-203-5p, miR-1201-5p, miR-149-5p, miR-671-3p, miR-944-5p, miR-27b-3p, and miR-22-3p have been identified to be significantly downregulated in adenocarcinoma versus normal and merely or not detectable in exosomes. "Exosomal onco-miRs" are a novel, stable, and noninvasive source for diagnosis and therapy monitoring of esophageal cancer. Oncogenic shuttle miRNAs present in exosomes may contribute to understanding how tumor cells spread their oncogenic potential to the environment. The "exosomal onco-miRs" identified seem to play a major role and may be applied for noninvasive diagnosis and therapy monitoring of adenocarcinoma of the esophagus.