Positive Reciprocal Feedback of lncRNA ZEB1-AS1 and HIF-1α Contributes to Hypoxia-Promoted Tumorigenesis and Metastasis of Pancreatic Cancer

Abstract

BackgroundMany studies have reported the roles of the extracellular hypoxia microenvironment in the tumorigenesis and metastasis of multiple cancers. However, long noncoding RNAs (lncRNAs) that induce cancer oncogenicity and metastasis of pancreatic cancer (PC) under hypoxia conditions remain unclear.MethodsIn PC cells, the expression levels of lncRNAs in different conditions (normoxia or hypoxia) were compared through RNA sequencing (RNA-seq). The effects of the zinc finger E-box-binding homeobox 1 (ZEB1-AS1) antisense lncRNA on PC cells cultured in normoxia/hypoxia medium were measured through gain and loss-of-function experiments. Fluorescence in situ hybridization and luciferase reporter assays in addition to in vivo studies were utilized to explore the adaptive mechanisms of ZEB1-AS1 in the hypoxia-promoted proliferation, migration, and invasion ability of PC cells. Moreover, the level of ZEB1-AS1 and its associated targets or pathways were investigated in both PC and pancreatic normal tissues.ResultsRNA-seq revealed that ZEB1-AS1 was significantly upregulated in PC cells under hypoxia conditions. The ZEB1-AS1 expression level was closely associated with poor prognosis of PC patients. Knockdown of ZEB1-AS1 suppressed the proliferation, migration, and invasion of PC cells in vitro as well as PC xenograft tumor growth in vivo. In PC cells, RNAi-mediated reduction of ZEB1-AS1 inhibited zinc finger E-box-binding homeobox 1 (ZEB1), while ZEB1-AS1 overexpression rescued ZEB1 expression, indicating that ZEB1-AS1 promotes ZEB1 expression. Moreover, hypoxia-inducible factor-1α (HIF-1α)induced the expression of ZEB1-AS1 by binding to the ZEB1-AS1 promoter, which contains a putative hypoxia response element (HRE). Mechanistically, ZEB1-AS1 scaffolded the interaction among HIF-1α, ZEB1, and histone deacetylase 1 (HDAC1), leading to deacetylation-mediated stabilization of HIF-1α. We further revealed that ZEB1 induced the deacetylase capacity of HDAC1 to suppress the acetylation or degradation of HIF-1α, improving HIF-1α assembly. Thus, hypoxia-induced ZEB1-AS1 facilitated ZEB1 transcription and the stability of HIF-1α, which promoted the metastasis of PC cells. Clinically, dysregulated ZEB1 and HIF-1α expression was significantly correlated with histological grade, lymphatic metastasis, and distant metastasis in PC patients.ConclusionsOur results emphasized that the positive reciprocal loop of HIF-1α/ZEB1-AS1/ZEB1/HDAC1 contributes to hypoxia-promoted oncogenicity and PC metastasis, indicating that it might be a novel therapeutic target for PC.

The m7G-Related Long Noncoding RNA Signature Predicts Prognosis and Indicates Tumour Immune Infiltration in Colon Cancer

“…In published research, the lncRNA ZEB1-AS1 was considered to be tightly related to the onset and progression of many types of cancers. According to Jin’s research, the positive reciprocal looping of HIF-1/ZEB1-AS1/ZEB1/HDAC1 leads to hypoxia-induced oncogenicity and PC metastasis ( Jin et al, 2021 ). Siena confirmed that lncRNA ZEB1-AS1 can influence the invasiveness and phenotypic transformation of melanoma through epithelial to mesenchymal transition (EMT) ( Siena et al, 2019 ).…”

Natural antisense transcripts as drug targets

“…Furthermore, ZEB1-AS1 scaffolded the interaction of HIF-1α, ZEB1, and HDAC1, leading to deacetylation and stabilization of HIF-1α protein, thus forming a positive feedback loop. Knockdown of ZEB1-AS1 inhibited progression and metastasis of pancreatic cancer in nude mice (Jin et al, 2021).…”

The role of LncRNA-MANCR induced by HIF-1a drive the malignant progression of pancreatic cancer by targeting miRNA-494/SIRT1 signaling axis under hypoxic conditions

“…Furthermore, lncRNA-nuclear transport factor 2 pseudogene 3 (NUTF2P3)-001 increased Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) expression by overcoming the suppression of KRAS via miR-3923 in PC cells 16 . Additionally, under hypoxic conditions, ZEB1-AS1 increased the transcription of ZEB1 and stabilised HIF-1α in PC cells 17 . However, the crucial function of lncRNAs needs to be understood to identify latent mechanisms and improve potential therapeutic strategies for patients with PC.…”

“…The chromatin immunoprecipitation (ChIP) analysis was conducted using Abcam's ChIP Kit (catalogue# ab500) and anti-HIF-1α (1:1,000, catalogue#ab51608) antibody as per the manufacturer's instructions 16,17 . Rabbit IgG (catalogue # ab172730; Abcam) was used as the control.…”