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

Purpose Accumulating evidence has focused on the vital roles of long non-coding RNAs (lncRNAs) in the hypoxic extracellular microenvironment of multiple human tumours. This study revealed the prospective biological role and fundamental mechanisms of hypoxia-induced lncRNA-MANCR (MANCR), which is notably upregulated in pancreatic cancer (PC). This work uncovered the potential biological function and underlying mechanisms of hypoxia-induced MANCR, which is significantly elevated in PC. Methods Microarray assays confirmed MANCR expression in the tissues of patients with PC and patients with chronic pancreatitis (CP), which positively correlated with sirtuin-1 (SIRT1) mRNA levels. In PC cells, lncRNA expression levels were compared using RNA sequencing. The impact of MANCR on tumour proliferation and metastasis of PC cells and in vivo models cultured under either normoxic or hypoxic conditions was evaluated using gain- and loss-of-function experiments. Chromatin immunoprecipitation and luciferase assays were employed to gauge binding within the hypoxia-inducible factor-1α (HIF-1α)/MANCR/miRNA-494/SIRT1 pathway. Additionally, the association between MANCR expression and the clinical outcomes of patients with PC was confirmed. Results MANCR is significantly upregulated in PC cells under hypoxic conditions, which is closely linked to poor prognosis in patients with PC. Depletion of MANCR repressed in vitro proliferation, migration, and invasion of PC cells and in vivo growth of PC xenograft tumours. We further demonstrated that MANCR is localised in the cytoplasm and competitively binds miR-494, which directly targets SIRT1. Mechanically, overexpression of SIRT1 improved the stability of the HIF-1α protein through deacetylation, leading to enhanced HIF-1α assembly. Moreover, MANCR underwent transcriptional regulation by HIF-1α in a hypoxic setting. This modulation was ascribed to HIF-1α binding to hypoxia response elements present in the MANCR promoter sequence. Furthermore, increased MANCR expression corresponded with lymphatic and distant metastases in patients with PC. Conclusions All data revealed the potential possibility of feedback between MANCR and HIF-1α, which may be conducive to hypoxia-induced oncogenicity and PC tumorigenesis, thereby providing a suitable therapeutic target.