IDENTIFICATION OF MIRNA PANEL IN DIFFERENT TYPES OF ENDOMETRIOSIS AND OVARIAN CANCER

Introduction/Background*Development of EAOC (Endometriosis associated ovarian cancer) has been intensively studied in the last few years. Epigenetic regulation of genes could play an important role in this process. The objective of this study was to identify miRNAs which expression was dysregulated both in EAOC and different types of endometriosis.MethodologyMaterial and methods: Case-control study comprised patients with ovarian endometriosis (n=47), deep infiltrating endometriosis (DIE)(n= 14), endometriosis in caesarean scar (n= 30), as well as patients with clear cell and endometrioid ovarian cancer (n= 26). For control group normal ovarian tissue from patients operated on for benign uterine pathology (n=33) and high grade ovarian cancer (HGOC) samples (n=29) were obtained. Total RNA was isolated from 1–2 tissue slices from archival formalin-fixed paraffin embedded (FFPE) blocks using the High Pure FFPET Isolation Kit (Roche). miRNA expression was first screened using TaqMan® Human MicroRNA Array A and B (Applied Biosystems). The expression levels of 754 human miRNA genes were assessed firstly in the groups of patients with EAOC (n=10) and healthy controls (n=10). MiRNAs with altered expression profiles were then chosen for further investigations. Quantification of these selected miRNA was done using TaqMan Advanced MicroRNA Assays (Applied Biosystems). The miRNA level was calculated as 2−ΔΔC t, while relative expression analysis of the examined gene was presented as an n-fold change in gene expression normalized to a reference gene relative to the control.Result(s)*Several miRNAs were highly dysregulated between healthy ovarian tissue and EAOC tissue: hsa-miR-1-3p, hsa-miR-31-3p, hsa-miR-125b-1-3p, hsa-miR-200b, miR548d. Validation revealed that the level of all tested miRNAs was only slightly higher in endometrial cysts comparing to normal ovarian tissue, but significantly higher in DIE foci and all types of ovarian cancer, including HGOC. The only miRNA that were able to discriminate between EAOC and HGOC was miR-1-3p which showed high expression in EAOC and lack of expression in HGOC.Conclusion*The same pattern of miRNA expression in DIE and EAOC, but not in endometrial cysts, could help to predict epigenetic changes that may be responsible for carcionogenesis in endometriosis foci.