BACKGROUND: There is a critical need for improved diagnostic markers for high 
grade serous epithelial ovarian cancer (SEOC). MicroRNAs are stable in the 
circulation and may have utility as biomarkers of malignancy. We investigated 
whether levels of serum microRNA could discriminate women with high-grade SEOC 
from age matched healthy volunteers.
METHODS: To identify microRNA of interest, microRNA expression profiling was 
performed on 4 SEOC cell lines and normal human ovarian surface epithelial 
cells. Total RNA was extracted from 500 μL aliquots of serum collected from 
patients with SEOC (n = 28) and age-matched healthy donors (n = 28). Serum 
microRNA levels were assessed by quantitative RT-PCR following preamplification.
RESULTS: microRNA (miR)-182, miR-200a, miR-200b and miR-200c were highly 
overexpressed in the SEOC cell lines relative to normal human ovarian surface 
epithelial cells and were assessed in RNA extracted from serum as candidate 
biomarkers. miR-103, miR-92a and miR -638 had relatively invariant expression 
across all ovarian cell lines, and with small-nucleolar C/D box 48 (RNU48) were 
assessed in RNA extracted from serum as candidate endogenous normalizers. No 
correlation between serum levels and age were observed (age range 30-79 years) 
for any of these microRNA or RNU48. Individually, miR-200a, miR-200b and 
miR-200c normalized to serum volume and miR-103 were significantly higher in 
serum of the SEOC cohort (P < 0.05; 0.05; 0.0005 respectively) and in 
combination, miR-200b + miR-200c normalized to serum volume and miR-103 was the 
best predictive classifier of SEOC (ROC-AUC = 0.784). This predictive model 
(miR-200b + miR-200c) was further confirmed by leave one out cross validation 
(AUC = 0.784).
CONCLUSIONS: We identified serum microRNAs able to discriminate patients with 
high grade SEOC from age-matched healthy controls. The addition of these 
microRNAs to current testing regimes may improve diagnosis for women with SEOC.