Identification of Circular RNA circ_0017068 as a Regulator of Proliferation and Apoptosis in Trophoblast Cells by miR-330-5p/XIAP Axis

Preeclampsia (PE) is a major and serious complication of pregnancy. Circular RNAs (circRNAs) have been implicated in the initiation and progression of PE. In this paper, we explored the precise actions of circ_0017068 in trophoblast cell functional properties. Ribonuclease (RNase) R, and Actinomycin D treatments were used to characterize circ_0017068. The levels of circ_0017068, MicroRNA (miR)-330-5p and X-linked inhibitor of Apoptosis protein (XIAP) were measured by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot analysis. Cell proliferation, cell cycle progression, and Apoptosis were gauged by the Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), and flow cytometry assays, respectively. Direct relationship between miR-330-5p and circ_0017068 or XIAP was validated by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Our data showed that circ_0017068 was downregulated in PE placental samples. Enforced expression of circ_0017068 promoted HTR-8/SVneo cell proliferation, cycle progression, and suppressed Apoptosis, while silencing of circ_0017068 exhibited opposite effects. Mechanistically, circ_0017068 targeted miR-330-5p, and circ_0017068 regulated proliferation, cycle progression, and Apoptosis of HTR-8/SVneo cells through miR-330-5p. Moreover, XIAP was identified as a direct and functional target of miR-330-5p. Furthermore, circ_0017068 operated as a post-transcriptional regulator of XIAP expression through miR-330-5p. Our study identifies circ_0017068 as an important regulator of the proliferation and Apoptosis of HTR-8/SVneo trophoblast cells at least in part by miR-330-5p-dependent regulation of XIAP, highlighting circ_0017068 as a potential therapeutic agent for PE treatment.