MicroRNA-17 downregulates expression of the PTEN gene to promote the occurrence and development of adenomyosis.

The aim of the current study was to evaluate the expression of microRNA (miR)-17 in the endometrial tissues of patients with adenomyosis (AM) and determine its biological function in the occurrence and development of the disease. A total of 45 fresh endometrial tissues of AM patients and 32 normal endometrial tissues were collected from healthy controls. The expression of miR-17 was evaluated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The miR-17-targeting gene phosphatase and tensin homolog (PTEN) was predicted using bioinformatics and its expression was evaluated with RT-qPCR and western blot analysis. Endometrial cells were isolated from patients with AM and healthy controls. They were cultured in vitro and transfected with antagomiR-17 to downregulate miR-17 expression, subsequently cell viability and apoptosis were measured using MTT and flow cytometry. The expression of PTEN and cell cycle- and apoptosis-related proteins were evaluated using western blot analysis. Endometrial cells that stably overexpressed PTEN were screened in vitro by co-culture with G418. A dual-luciferase reporter assay was conducted to verify whether miR-17 was directly bound to PTEN mRNA. The results demonstrated that expression of miR-17 was significantly increased in the endometrial tissues of patients with AM compared with control patients (P<0.05). PTEN mRNA and protein expression were significantly lower in the AM group compared with the control group (P<0.05). When the expression of miR-17 in the cells was downregulated, the expression of PTEN was significantly increased (P<0.05). In addition, expression of Bcl-2 protein was significantly decreased and that of Bax protein significantly increased compared with the negative control (both P<0.05). The expression of cyclins E1 and D1 were also significantly downregulated (P<0.05). When PTEN was overexpressed or miR-17 was downregulated, the viability of endometrial cells significantly decreased and cell apoptosis significantly increased (all P<0.05). A dual-luciferase reporter assay indicated that miR-17 could directly bind to the PTEN mRNA 3'-untranslated region to regulate its expression. Thus the current study indicates that expression of miR-17 was increased in the endometrial tissues of patients with AM and may influence cell apoptosis and cyclin expression through the targeted regulation of PTEN. These results suggest that miR-17 promotes the occurrence and development of AM.