Exosomal microRNAs as tumor markers in epithelial ovarian cancer

Specific microRNAs (miRNAs) are packaged in exosomes that regulate processes in tumor development and progression. The current study focuses on the influence of exosomal miRNAs in the pathogenesis of epithelial ovarian cancer (EOC). MiRNA profiles were determined in exosomes from plasma of 106 EOC patients, eight ovarian cystadenoma patients, and 29 healthy women by TaqMan real-time PCR-based miRNA array cards containing 48 different miRNAs. In cell culture experiments, the impact of miR-200b and miR-320 was determined on proliferation and apoptosis of ovarian cancer cell lines. We report that miR-21 (P = 0.0001), miR-100 (P = 0.034), miR-200b (P = 0.008), and miR-320 (P = 0.034) are significantly enriched, whereas miR-16 (P = 0.009), miR-93 (P = 0.014), miR-126 (P = 0.012), and miR-223 (P = 0.029) are underrepresented in exosomes from plasma of EOC patients as compared to those of healthy women. The levels of exosomal miR-23a (P = 0.009, 0.008) and miR-92a (P = 009, 0.034) were lower in ovarian cystadenoma patients than in EOC patients and healthy women, respectively. The exosomal levels of miR-200b correlated with the tumor marker CA125 (P = 0.002) and patient overall survival (P = 0.019). MiR-200b influenced cell proliferation (P = 0.0001) and apoptosis (P < 0.008). Our findings reveal specific exosomal miRNA patterns in EOC and ovarian cystadenoma patients, which are indicative of a role of these miRNAs in the pathogenesis of EOC.