Аннотация:Ovarian cancer (OC) is one of the most common types of cancer among malignancies of 19 the female reproductive system. This pathology is characterized by a high rate of mortality due to 20 the limited facilities of early diagnostics and related loss of effective treatment at the initial stages. 21 MicroRNAs (miRNAs) are suggested to play a role in local invasion and migration, angiogenesis, 22 epithelial-mesenchymal transition, and intravasation of malignant cells. Aberrant expression of 23 miRNAs leads to an imbalance in the complex formation between miRNAs, long non-coding RNAs 24 (lncRNA), and mRNAs. This study aimed to analyze the disturbance in lncRNA–miRNA–mRNA 25 competing triplets that promotes tumorigenesis in OC patients. For this purpose, we analyzed 26 tumor samples from the TCGA database and verified the results experimentally in a set of 46 paired 27 samples of tumor and matched histologically unchanged ovarian tissues from OC patients. The list 28 of in silico selected for experimental validation RNAs included 13 mRNAs, 10 lncRNAs, and 5 29 miRNAs related to epithelial-mesenchymal transition and angiogenesis. We evaluated the 30 expression of these RNAs by qRT-PCR and analyzed the correlation between levels of miRNAs, 31 mRNAs, and lncRNAs using Spearman’s coefficient. Sixteen significant triplets were revealed, 32 where OIP5-AS1–miR-203a–YAP1 and OIP5-AS1–miR-203a–ZEB2 had the potential for diagnostics 33 of metastasis early onse.