Endometrioid endometrial carcinoma (EEC) is one of the common cause of cancer-related mortality in women. Despite progress in diagnostics and treatment of EEC, its prognosis remains poor. Mounting evidence suggest that long noncoding RNAs (lncRNAs) function in mutiple human cancers. Aberrant lncRNA expression may predict tumor outcome of patients and have served as diagnostic or prognostic markers. In this study, we investigated the expression levels and functions of lncRNAs in EEC.
Differentially expressed lncRNAs involved in EEC were identified by using publically available RNA-Seq data. The expression of 18 dysregulated lncRNA candidates was verified in 5 NE tissues, 5 EEC tissues and 5 EEC cell lines (HEC1-A, HEC1-B, AN3CA, KLE and RL95-2) by real-time polymerase chain reaction (PCR). Further, we selected the most misexpressed lncRNA and confirmed the expression level of the lncRNA in 59 EEC tissues and 24 NE tissues by real-time PCR and correlated the lncRNA expression levels with the clinical pathological characteristics. The promoter methylation assay was used to analyze the methylation level of the lncRNA in EEC. The lncRNA methylation status was confirmed by bisulfite genomic sequencing. Cell proliferation assays, wound healing assays, and invasion and migration assays were performed to determine the biological functions of the lncRNA in EEC cells. To discover the direct targets of the lncRNA in EEC, we performed RNA-sequence analysis in EEC cells overexpressed with the lncRNA and target genes were further studied by functional studies in vitro (knockdown assay and overexpression rescue assay).
We discovered that HAND2-AS1, a lncRNA transcribed antisense adjacent to Heart and Neural Crest Derivatives Expressed 2 (HAND2), was significantly downregulated lncRNA in EEC. HAND2-AS1 and HAND2 was frequently downregulated in EEC tissues, especially in poor differentiated tumor tissues. Downregulation of HAND2-AS1 and HAND2 was correlated with tumor grade, lymph node metastasis and recurrence of EEC patients. HAND2-AS1 and HAND2 was co-downregulated by promoter hypermethylation in EEC. HAND2-AS1 suppressed EEC cell migration and invasion but not cell growth. Similarly, HAND2 also inhibited EEC cell migration and invasion indicating that HAND2-AS1 and HAND2 have a concordant role in the progression of EEC. Moreover, the anti-tumorigenic effect of HAND2-AS1 was mediated by downregulating NMU, which had an oncogenic role in EEC.
Our findings provide the first evidence that HAND2-AS1 is a critical tumor suppressor in EEC and may constitute a prognostic biomarker in EEC.
Note: This abstract was not presented at the meeting.
Citation Format: Xueying Yang, Yu Zhao, Kun Sun, Yuying Li, Jiajian Zhou, Jianzhang Wang, Hao Sun, Chi Chiu Wang, Joseph Kwong, Huating Wang, Tony Kwok Hung Chung. LncRNA HAND2-AS1 inactivates neuromedin U (NMU) and inhibits tumor invasion and metastasis in endometrioid endometrial carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3448. doi:10.1158/1538-7445.AM2017-3448