lncRNA <i>THAP9-AS1</i> Promotes Pancreatic Ductal Adenocarcinoma Growth and Leads to a Poor Clinical Outcome via Sponging miR-484 and Interacting with YAP.

Li, Nan; Yang, Guohua; Luo, Liyun; Ling, Li; Wang, Xiaorong; Shi, Lejuan; Lan, Junsong; Jia, Xiaoting et al. · Clin Cancer Res · 2020

basic_science · Level V

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Abstract

Long noncoding RNAs (lncRNA) have been observed in various cancer types. Our bioinformatic analysis of existing databases demonstrated overexpression of lncRNA <i>THAP9-AS1</i> in pancreatic ductal adenocarcinoma (PDAC). We aimed to investigate the roles and mechanisms of <i>THAP9-AS1</i> in PDAC. The overexpression of <i>THAP9-AS1</i> in samples of patients with pancreatic cancer was characterized and was associated with clinical outcomes. The nonprotein coding property of the <i>THAP9-AS1</i> was verified. Various <i>in vitro</i> and <i>in vivo</i> experiments were performed to investigate the interaction between <i>THAP9-AS1</i> and YAP signaling. We demonstrated that lncRNA <i>THAP9-AS1</i> is overexpressed in PDAC in multiple patient sample sets, which is significantly associated with poor outcome of patients with PDAC. <i>THAP9-AS1</i> promotes PDAC cells growth both <i>in vitro</i> and <i>in vivo</i>. <i>THAP9-AS1</i> exerts its effects via enhancing YAP signaling. Ectopic YAP expression overcame the effects of <i>THAP9-AS1</i> knockdown. Inversely, YAP knockdown diminished the effects of <i>THAP9-AS1</i> overexpression. <i>THAP9-AS1</i> acts as a competing endogenous RNA for miR-484, leading to YAP upregulation. Moreover, <i>THAP9-AS1</i> binds to YAP protein and inhibits the phosphorylation-mediated inactivation of YAP by LATS1. Reciprocally, YAP/TEAD1 complex promotes <i>THAP9-AS1</i> transcription to form a feed-forward circuit. Importantly, <i>THAP9-AS1</i> level positively correlates with YAP expression in PDAC tissues. YAP overexpression also predicts a poor outcome in patients with PDAC. Our findings indicate that <i>THAP9-AS1</i> plays an important role in PDAC growth via enhancing YAP signaling, which in turn also modulates <i>THAP9-AS1</i> transcription. <i>THAP9-AS1</i>/YAP axis may serve as a potential biomarker and therapeutic target for PDAC treatment.

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