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Abstract Background Extracellular vesicles (EVs) are considered as a new class of resources for potential biomarkers. We analyzed expression of specific mRNA and miRNA in EVs derived from ovarian cancer ascites and the ideal controls, peritoneal fluids from benign patients for potential early detection and prognostic biomarkers. Methods Fluids were collected from subjects with benign cysts or endometrioma (n = 10), or low/high grade serous ovarian carcinoma (n = 8). EV particles were captured using primarily ExoComplete filterplate or ultracentrifugation and analyzed by nanoparticle tracking analysis, ELISA, and scanning electron microscopy. EV RNAs extracted from two ascites and three peritoneal fluids were submitted for next-generation sequencing. The expression of 34 mRNA and 18 miRNAs in the EVs isolated from patient fluids and cell line media was determined using qPCR. Results EVs isolated from patient samples had concentrations greater than 1010 EV particles/mL and 30% were EpCAM-positive based on ELISA. EV particle sizes averaged 113 ± 11.5 nm. The qPCR studies identified five mRNA (CA11, MEDAG, LAMA4, SPINT2, NANOG) and six miRNA (let-7b, miR23b, miR29a, miR30d, miR205, miR720) that were significantly differentially expressed between cancer ascites and peritoneal fluids. In addition, CA11 mRNA was decreased to 0.5-fold and SPINT2 and NANOG mRNA were significantly increased up to 100-fold in conditioned media of cancer cells compared to immortalized ovarian surface and fallopian tube epithelial cell lines, the hypothesized cells of origin for ovarian cancer development. Conclusions This study indicates that EV mRNA profiles can reflect the disease stage and may provide a potentially novel source for discovery of biomarkers in ovarian cancer.

Abstract Background Ovarian cancer is the leading cause of death among gynecologic diseases in Western countries. We have previously identified a miR-200-E-cadherin axis that plays an important role in ovarian inclusion cyst formation and tumor invasion. The purpose of this study was to determine if the miR-200 pathway is involved in the early stages of ovarian cancer pathogenesis by studying the expression levels of the pathway components in a panel of clinical ovarian tissues, and fallopian tube tissues harboring serous tubal intraepithelial carcinomas (STICs), a suggested precursor lesion for high-grade serous tumors. Methods RNA prepared from ovarian and fallopian tube epithelial and stromal fibroblasts was subjected to quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) to determine the expression of miR-200 families, target and effector genes and analyzed for clinical association. The effects of exogenous miR-200 on marker expression in normal cells were determined by qRT-PCR and fluorescence imaging after transfection of miR-200 precursors. Results Ovarian epithelial tumor cells showed concurrent up-regulation of miR-200, down-regulation of the four target genes (ZEB1, ZEB2, TGFβ1 and TGFβ2), and up-regulation of effector genes that were negatively regulated by the target genes. STIC tumor cells showed a similar trend of expression patterns, although the effects did not reach significance because of small sample sizes. Transfection of synthetic miR-200 precursors into normal ovarian surface epithelial (OSE) and fallopian tube epithelial (FTE) cells confirmed reduced expression of the target genes and elevated levels of the effector genes CDH1, CRB3 and EpCAM in both normal OSE and FTE cells. However, only FTE cells had a specific induction of CA125 after miR-200 precursor transfection. Conclusions The activation of the miR-200 pathway may be an early event that renders the OSE and FTE cells more susceptible to oncogenic mutations and histologic differentiation. As high-grade serous ovarian carcinomas (HGSOC) usually express high levels of CA125, the induction of CA125 expression in FTE cells by miR-200 precursor transfection is consistent with the notion that HGSOC has an origin in the distal fallopian tube.