Chemotherapy resistance is one of the most common causes of death among patients with ovarian cancer, and identifying novel antitumor agents is a priority. Here, we report that the novel molecule 2‐(anaphthoyl)ethyl‐trimethylammonium iodide (α‐NETA) induces epithelial ovarian cancer (EOC) cell pyroptosis through the gesdermin‐d (GSDMD)/caspase‐4 pathway. Furthermore, Cell Counting Kit‐8 fluorescence‐activated cell sorting analysis showed that α‐NETA treatment led to cell death in different ovarian cancer cell lines, including Ho8910, Ho8910PM, and A2780. Morphologic examination by electron microscopy indicated that cells treated with α‐NETA produced multiple microbubbles, typical of cells undergoing pyroptosis. α‐NETA also significantly increased expression of pyroptosis‐associated molecules including caspase‐4 and GSDMD in EOC cells. Knockdown of either caspase‐4 or GSDMD in ovarian cancer cells strongly interfered with α‐NETA cell‐killing activity, indicating that α‐NETA acts through the pyroptosis pathway. In vivo, α‐NETA treatment dramatically decreased the size of EOC tumors in mice. Our findings suggest that α‐NETA represents a potential new antitumor molecule or lead compound for EOC chemotherapy.—Qiao, L., Wu, X., Zhang, J., Liu, L., Sui, X., Zhang, R., Liu, W., Shen, F., Sun, Y., Xi, X. α‐NETA induces pyroptosis of epithelial ovarian cancer cells through the GSDMD/caspase‐4 pathway. FASEB J. 33, 12760–12767 (2019). http://www.fasebj.org

Leucine‐rich repeat‐containing G protein‐coupled receptor 5 (LGR5) plays a vital role in the development of malignant tumors; however, its biological role and underlying mechanism in epithelial ovarian cancer (EOC) remain unclear. In this study, we aimed to investigate the biological function and clinical significance of LGR5 in human EOC. We evaluated LGR5 expression in EOC cell lines and tissues from ovarian cancer patients by qPCR, Western blotting, and immunohistochemical analysis. Cell proliferation, colony formation, transwell invasion assay, and scratch‐wound assays were conducted to evaluate the expansion and invasion abilities of EOC cells. Tumor xenograft experiments were performed in female BALB/c athymic nude mice to test cell proliferation in vivo. Western blot analysis was performed to confirm the expression of epithelial‐to‐mesenchymal transition (EMT) signature proteins and their association with Notch1 signaling. The results demonstrated that LGR5 was overexpressed in EOC tissues and cell lines. Aberrant expression of LGR5 was significantly associated with patient age (P = 0.006), tumor histologic type (P < 0.001), and distant metastasis (P = 0.025). Consistent with these findings, suppression of LGR5 expression led to decreased proliferation and metastasis of EOC cell lines. Furthermore, LGR5 could induce EMT and regulate the Notch1 signaling pathway. Taken together,LGR5 may have an important role in the promotion of tumorigenesis and metastasis of EOC and is a potential therapeutic target for EOC management.

Ovarian cancer (OC) is one of the most lethal malignancies worldwide and its tumorigenesis and progression are largely unknown. As an important class of endogenous regulatory non-coding RNAs, Circular RNAs play a critical role in various cancers. Our preliminary experiment discovered that hsa_circ_0013561 was aberrantly expressed in OC. However, the underlying mechanism is unclear. The expression of hsa_circ_0013561 in OC cells and tissues was detected by RT-qPCR and fluorescence in situ hybridization. The effects of hsa_circ_0013561 on the proliferation and metastasis of OC were explored by functional experiments such as cell counting kit 8, transwell, and tumor xenograft models. To mechanistically understand the regulatory role of hsa_circ_0013561, bioinformatics analysis, Western blot, luciferase reporter assay, and a series of rescue experiments were applied. We found that the hsa_circ_0013561 expression was elevated in OC cells and tissues, and was correlated with metastasis formation. Downregulation of hsa_circ_0013561 suppressed the proliferation and migration of OC cells both in vitro and in vivo. Regarding the interactions of hsa_circ_0013561, luciferase reporter assay verified that miR-23b-3p and Annexin A2 (ANXA2) were its downstream targets. MiR-23b-3p inhibition or ANXA2 overexpression reversed OC cell proliferation, migration, and epithelial-mesenchymal transition (EMT) post-hsa_circ_0013561 silencing. Moreover, ANXA2 overexpression also reversed OC cell migration, proliferation, and EMT after miR-23b-3p upregulation. Our data suggest that hsa_circ_0013561 increases the expression of ANXA2 through regulating miR-23b-3p competitively, resulting in EMT and metastasis of OC. Thus, hsa_circ_0013561 may serve as a novel oncogenic biomarker for OC progression.