IDDF2019-ABS-0200 Long non-coding RNA LOC148709 regulates PFKFB3-mediated glycolytic reprogramming in esophageal squamous cell carcinoma

Background Rapid proliferation and glucose metabolism remodeling are hallmarks of cancers. Long non-coding RNAs (lncRNAs) are potentially involved in Warburg effect. We aimed to identify oncogenic lncRNAs that significantly affect the development of esophageal squamous cell carcinoma (ESCC) and investigate the metabolism-related mechanisms. Methods Bioinformatics analysis and siRNA library screening were used to pinpoint lncRNAs that significantly affected cell glycolysis and proliferation. RNAScope(R) in situ hybridization and qRT-PCR assays were performed in clinical samples to investigate expression levels and clinical relevance of the lncRNA. RNA interference and CRISPR-Cas9 were used to explore the functional roles of the lncRNA. In vivo, cell-based and patient-derived xenograft (PDX) models were used. Extracellular acidification rate and 13C-labeled intracellular metabolites were determined. RNA pull-down, MS2-Tagged RNA affinity purification, RNA-binding protein immunoprecipitation and cross-linking immunoprecipitation were performed to identify lncRNA associated proteins and related mechanisms. Results The lncRNA LOC148709 was identified as a metabolism-related lncRNA. Increased expression of LOC148709 was observed in ESCC and was correlated with poor prognosis. LOC148709 knockdown significantly decreased cell proliferation and glycolysis. Mechanistically, LOC148709 was directly associated with PFKFB3 and significantly affected PFKFB3 stability. LOC148709 interacted mainly with the C-terminal fragment of PFKFB3 and the T5 (2031–2321) fragment of LOC148709 mediated the interaction with PFKFB3. Through inhibiting K302 ubiquitination, LOC148709 protected PFKFB3 from proteasomal degradation, which subsequently activated glycolytic flux and promoted cell cycle progression by regulating p27 and CDK1. P53 could bind to the LOC148709 promoter and repress its transcription, p53 loss or mutation triggered striking LOC148709 upregulation. Multiple micro-environmental factors, including hypoxia and oncogenic stress, were also involved in the LOC148709 regulatory network via affecting the status of p53. Notably, our patient-derived xenograft (PDX) model studies demonstrated that LOC148709 knockdown dramatically impaired tumor growth. Conclusions The lncRNA LOC148709 plays an essential role in glycolytic reprogramming by binding to and stabilizing PFKFB3. This study identified a novel metabolism-related lncRNA and revealed a novel mechanism underlying lncRNA-mediated cancer metabolism remodeling. Translational studies further implicated that LOC148709 is a promising biomarker for cancer diagnosis and therapy.