Abstract
High metastatic potential and resistance to immunotherapy lead to poor survival in patients with ovarian cancer. Angiopoietin-like protein 3 is aberrantly expressed and exerts diverse roles in the progression of several cancers. However, its function in ovarian cancer is unknown. Here, decreased expression of angiopoietin-like protein 3 was observed in ovarian cancer tissues and cells. Moreover, patients with high expression of angiopoietin-like protein 3 had longer overall survival and progression-free survival, indicating a good prognosis for patients. Furthermore, angiopoietin-like protein 3 overexpression inhibited ovarian cancer cell proliferation. Concomitantly, high invasion and the occurrence of epithelial-to-mesenchymal transition of cancer cells were restrained after angiopoietin-like protein 3 elevation. Up-regulation of angiopoietin-like protein 3 expression further increased interleukin 2-treated natural killer cell activation by increasing CD69 expression and production of interferon gamma and tumor necrosis factor-alpha when natural killer cells were co-cultured with ovarian cancer cells. Importantly, angiopoietin-like protein 3 overexpression enhanced natural killer cell-evoked cytotoxicity and apoptosis of cancer cells, indicating the pro-tumor killing ability of angiopoietin-like protein 3 for natural killer cells. Mechanistically, angiopoietin-like protein 3 elevation inhibited activation of the Janus Kinase/Signal transducer and activator of transcription 3 signaling in ovarian cancer cells by inhibiting protein expression of phospho-Janus Kinase 2, phospho-Signal transducer and activator of transcription 3, downstream matrix metallopeptidase 2 and programmed cell death 1. Moreover, blocking the Janus Kinase/Signal transducer and activator of transcription 3 pathway via their inhibitor Stattic restrained ovarian cancer cell proliferation, invasion, epithelial-to-mesenchymal transition, and promoted natural killer cell killing to ovarian cancer cells. Thus, these findings reveal that angiopoietin-like protein 3 may act as an anti-oncogenic regulator to inhibit the metastatic potential and enhance the susceptibility of ovarian cancer cells to natural killer cell-mediated killing. Consequently, angiopoietin-like protein 3 may regulate metastatic potential and immune escape from natural killer cells, indicating a promising therapeutic strategy for ovarian cancer.