Expression and clinical significance of estrogen-regulated long non-coding RNAs in estrogen receptor α-positive ovarian cancer progression

Estrogen (E2) has long been implicated in epithelial ovarian cancer (EOC) progression. The effects of E2 on cancer progression can be mediated by numerous target genes, including coding RNAs and, more recently, non-coding RNAs (ncRNAs). Among the ncRNAs, long ncRNAs (lncRNAs) have emerged as new regulators in cancer progression; therefore, our aim was to determine whether the expression of any lncRNAs is regulated by E2 and, if so, whether a subset of these lncRNAs have some clinical significance in EOC progression. A microarray was performed to identify E2-regulated lncRNAs in E2 receptor (ER) alpha-positive EOC cells. Bioinformatics analyses of lncRNAs were conducted, focusing on Gene Ontology and pathway analyses. Quantitative real-time polymerase chain reactions were performed to confirm the expression of certain lncRNAs in ER alpha-positive EOC tissues. The correlation between certain lncRNA expression and clinicopathological factors as well as prognosis in ER alpha-positive EOC patients was then analyzed. We showed that 115 lncRNAs exhibited significant changes in E2-treated SKOV3 cells compared with untreated controls. Most of these lncRNAs were predicated to have potential to contribute to cancer progression. Notably, three candidates (TC0100223, TC0101686 and TC0101441) were aberrantly expressed in ER alpha-positive compared to ER alpha-negative EOC tissues, showing correlations with some malignant cancer phenotypes such as advanced FIGO stage and/or high histological grade. Furthermore, multivariate analysis indicated that TC0101441 was an independent prognostic factor for overall survival. Taken together, these results indicate for the first time that E2 can modulate lncRNA expression in ER alpha-positive EOC cells and that certain lncRNAs are correlated with advanced cancer progression and suggestive of a prognostic indicator in ER alpha-positive EOC patients. Knowledge of these E2-regulated lncRNAs could aid in the future understanding of the estrogenic effect on EOC progression and may assist in the clinical design of new target therapies based on a perspective of lncRNA.