Background: Ovarian cancer (OV) is a common and lethal gynaecological malignancy, remaining to be a great health concern for women globally. Long non-coding RNAs (lncRNAs), RNA transcripts with little protein-coding potential, are found to be closely associated with cancer progression. Mesenchymal-like ovarian cancer is considered as the most aggressive subtype of ovarian cancer, yet the role of lncRNAs in subtyping of this cancer is not well-studied.
Method: We performed integrative network analysis with TCGA-OV data to identify the mesenchymal-like OV-specific master regulator lncRNA related to epithelial-mesenchymal transition (EMT). We used 3D cultures, tumour sphere formation assays, Transwell migration invasion assays and xenograft OV metastasis model for the functional characterization. We also validated the downstream effector with qPCR, immunoblotting and mRNA stabilization assays. ENCORI platform was utilized to predict the direct mediator between the lncRNA and target effector gene. RNA immunoprecipitation (RIP) was employed to validate the direct binding with the mediator.
Results: ZFHX4-AS1 was identified as a master regulator of EMT that is upregulated in the mesenchymal-like subtype. ZFHX4-AS1 promotes ovarian cancer cell migration, invasion and stemness in vitro and enhances peritoneal metastasis in vivo. We also identified a target Gene X, was stabilized by ZFHX4-AS1. We showed direct binding of HuR, a mRNA stabilizing protein, with ZFHX4-AS1 and Gene X mRNA. We further demonstrated that HuR plays a critical role in enhancing the expression level of Gene X.
Conclusion: Our findings identified ZFHX4-AS1 as a novel lncRNA that drives mesenchymal-like ovarian cancer progression, and uncovered HuR and Gene X as its interacting molecular partners.