Circular RNAs (circRNAs) are involved in the pathogenesis of many diseases, although their expression pattern and role in endometriosis remains unknown. Therefore, here, we profiled the expression patterns of circRNAs in ovarian ectopic and paired eutopic endometria as well as constructed a circRNA–miRNA–mRNA network. Circular RNA and messenger RNA (mRNA) expression profiles were assessed by a microarray analysis in 4 patients. Quantitative real-time polymerase chain reaction (qRT-PCR) validation of 8 circRNAs and mRNAs was conducted in another 37 patients. We detected 1258 up- and 1061 downregulated circRNAs as well as 1900 up- and 2535 downregulated mRNAs between the ectopic and eutopic endometria. Functional analysis suggested that most differentially expressed mRNAs participate in immune–inflammatory responses and cell cycle regulation. The qRT-PCR validation results for 5 circRNAs (circ_0004712, circ_0002198, circ_0003570, circ_0008951, and circ_0017248) and 8 mRNAs (SCN3B, ENTPD1, IL16, BACH2, C3, CKS2, G0S2, and PGRMC1) matched the microarray results. On basis of target prediction, we constructed a circRNA–miRNA–mRNA network. This revealed the primary roles of cancer-related, purine metabolism, glycerophospholipid metabolism, and thyroid hormone signaling pathways in endometriosis pathogenesis. This is the first study of circRNA expression patterns in ovarian endometriosis, which suggests that circRNAs are candidate factors in the activation of ovarian endometriosis and are promising diagnostic biomarkers and treatment targets.
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