Ten-eleven translocation 1 (TET1) is a dioxygenase that converts 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC) to induce DNA demethylation. TET1 has been reported to be absent in cancers, and to influence various oncogenes and anti-oncogenes. However the function of TET1 in pancreatic tumor remains poorly understood. In this study, we investigated the role of TET1 in the progression of pancreatic tumor and its mechanism of tumor suppression. Quantitative real-time PCR (qRT-PCR), immunohistochemical (IHC) staining and dot blot were performed to detect the TET1 and 5-hmC expression in pancreatic tumor tissues and its adjacent non-tumor tissues. The clinical parameters significance of pancreatic tumor tissues was determined statistically. TET1 over-expression and knock-out cell lines were built and confirmed in vitro. Cell proliferation assay, wound-healing assays, transwell migration assay and nude mice model of orthotopic pancreatic cancer implantation were performed to assess the function of TET1 in pancreatic tumor. Western blot, qRT-PCR, immunofluorescence (IF), bisulfate sequencing (BSP), Chromatin immunoprecipitation (ChIP) were used to uncover the mechanism. TET1 levels and 5-hmC content were downregulated in pancreatic tumor tissues and cell lines, and pancreatic tumor patients with low TET1 levels had a shorter overall survival than patients with high levels of TET1. TET1 suppressed pancreatic tumor proliferation and metastasis in vivo and in vitro. TET1 bound to the secreted frizzled-related protein 2 (SFRP2) promoter and catalyzed demethylation to activate transcription of SFRP2, inhibiting both the canonical and non-canonical Wnt signaling pathways, and ultimately obstructing epithelial-mesenchymal transition (EMT) in pancreatic tumors. We found TET1 plays as a suppressor in pancreatic tumor progression via obstructing Wnt signaling pathways.

Background: Although a substantial increase in the survival of patients with other cancers has been observed in recent decades, pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest diseases. No effective screening approach exists. Methods: Differential exosomal long noncoding RNAs (lncRNAs) isolated from the serum of patients with PDAC and healthy individuals were profiled to screen for potential markers in liquid biopsies. The functions of LINC00623 in PDAC cell proliferation, migration and invasion were confirmed through in vivo and in vitro assays. RNA pulldown, RNA immunoprecipitation (RIP) and coimmunoprecipitation (Co-IP) assays and rescue experiments were performed to explore the molecular mechanisms of the LINC00623/NAT10 signaling axis in PDAC progression. Results: A novel lncRNA, LINC00623, was identified, and its diagnostic value was confirmed, as it could discriminate patients with PDAC from patients with benign pancreatic neoplasms and healthy individuals. Moreover, LINC00623 was shown to promote the tumorigenicity and migratory capacity of PDAC cells in vitro and in vivo. Mechanistically, LINC00623 bound to N-acetyltransferase 10 (NAT10) and blocked its ubiquitination-dependent degradation by recruiting the deubiquitinase USP39. As a key regulator of N4-acetylcytidine (ac4C) modification of mRNA, NAT10 was demonstrated to maintain the stability of oncogenic mRNAs and promote their translation efficiency through ac4C modification. Conclusions: Our data revealed the role of LINC00623/NAT10 signaling axis in PDAC progression, showing that it is a potential biomarker and therapeutic target for PDAC.

Integrated expression profiles analysis reveals novel predictive biomarker in pancreatic ductal adenocarcinoma