LncRNA PVT1 promotes the progression of ovarian cancer by activating TGF-β pathway via miR-148a-3p/AGO1 axis

Ovarian cancer is a lethal gynaecologic malignancy with poor diagnosis and prognosis. The long non-coding RNA plasmacytoma variant translocation1 (PVT1) and argonaute 1 (AGO1) are associated with carcinogenesis and chemoresistance; however, the relationship between PVT1 and AGO1 and the downstream mechanisms in ovarian cancer remains poorly known. PVT1 and AGO1 expression was assessed through RT-qPCR and Western blotting in both human tissues and cell lines. The viability and proliferation of ovarian cancer cells were determined by CCK-8 assay and TUNEL assay in vitro and immunohistochemistry in vivo. Cell invasion and migration were investigated through transwell and wound-healing assays. The roles and mechanisms of AGO1 on cell functions were further probed via gain- and loss-of-function analysis. We reveal that PVT1 expression was significantly increased in ovarian cancer tissues which is associated with advanced FIGO stage, lymph-node metastasis, poor survival rate, and high expression of AGO1. PVT1 or AGO1 knockdown significantly reduced the cell viability and increased the cell apoptosis and inhibited ovarian tumour growth and proliferation. Furthermore, we discovered that PVT1 up-regulated the expression of AGO1 and thus regulated the transforming growth factor-beta (TGF-beta) pathway to promote ovarian cancer progression through sponging miR-148a-3p. Additionally, the activation of ERK1/2, smad2 and smad4 is observed to be related to the PVT1/miR-148a-3p/AGO1/TGF-beta pathway-induced cascades. Taken together, the present study reveals that PVT1/miR-148a/AGO1 axis plays an important role in the progression of ovarian cancer and emphasize the potential as a target of value for ovarian cancer therapy.