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Targeting Wnt/β-Catenin Signaling by TET1/FOXO4 Inhibits Metastatic Spreading and Self-Renewal of Cancer Stem Cells in Gastric Cancer.

ABSTRACT: Metastasis is the main cause of death for patients suffering gastric cancer. Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSC) are critical attributes of metastasis, both of which are regulated tightly by DNA methylation and Wnt/β-catenin signaling. Here, we studied the functions of DNA dioxygenase TET1 in regulating Wnt signaling and in gastric cancer metastasis. Knocking-down and overexpressing TET1 in gastric cancer cells promoted and inhibited metastatic spreading to the liver in immune-deficient mice, respectively. TET1 showed inhibitory effects on metastasis-related features -EMT and CSC, which were reversed by interfering with Wnt/β-catenin signaling. RNA-sequencing identified FOXO4 as a direct transactivating target of TET1. FOXO4 directly interacted with β-catenin and recruited it in the cytoplasm, so as to inhibit β-catenin-mediated transcription of Wnt target genes, including CSC marker EpCAM. Moreover, modulation of FOXO4 could reverse the effects of TET1 manipulation on EMT and self-renewal of CSCs. The analysis with clinical samples confirmed the value of FOXO4 as an independent prognostic predictor of patients' overall survival. Taken together, regulation of Wnt signaling by TET1/FOXO4 is essential for metastasis-associated cellular properties, and targeting TET1/FOXO4/β-catenin pathway may serve as promising therapeutics in the prevention and treatment of gastric cancer metastasis.

SUBMITTER: Qi J

PROVIDER: S-EPMC9264907 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundGlobally, gastric cancer (GC) is one of the world's most widespread malignancies, with persistent high mortality and morbidity rates. Increasing evidence now suggests that microRNAs (miRNAs) participate in many biological processes, with miR-455-3p having key roles in the progression of diverse cancers. Nevertheless, miR-455-3p function and expression in GC remain unclear.MethodsWe explored miR-455-3p expression in GC using quantitative polymerase chain reaction (qPCR). To further examine the effect of miR-455-3p in GC, after transfecting miR-455-3p mimics or inhibitors into GC cells, 5-ethynyl-2'-deoxyuridine (EdU) incorporation and colony formation assays were performed to examine cell proliferation. Flow cytometry was used to detect apoptosis, and expression levels of Bax, Bcl-2, Snail, N-cadherin, E-cadherin, and Caspase-3 were assessed by western blotting (WB). Using online databases and luciferase assays, we identified armadillo repeat-containing protein 8 (ARMC8) as a promising target of miR-455-3p. A mouse tumor model was established to investigate actions of miR-455-3p in vivo. Expression levels of C-myc, cyclinD1, and β-catenin were examined using WB and immunofluorescence.ResultsMiR-455-3p expression was attenuated in GC tissue and cell lines. MiR-455-3p overexpression inhibited GC cell proliferation, epithelial-mesenchymal transition (EMT), as well as facilitated apoptosis, while suppression of miR-455-3p had the opposite effects. From luciferase assays, we confirmed that ARMC8 was a novel and direct downstream target gene of miR-455-3p, and that the tumor suppressive role of miR-455-3p was in part reversed due to ARMC8 overexpression. Moreover, miR-455-3p inhibited GC growth in vivo via ARMC8. We also observed that miR-455-3p repressed canonical Wnt pathway activation by binding to ARMC8.ConclusionsMiR-455-3p exerted tumor inhibitory effects in GC by targeting ARMC8. Therefore, intervening in the miR-455-3p/ARMC8/Wnt/βcatenin axis could be a promising novel treatment strategy for GC.

Project description:BackgroundGastric cancer is one of the most common malignant tumors. Cyclin G2 has been shown to be associated with the development of multiple types of tumors, but its underlying mechanisms in gastric tumors is not well-understood. The aim of this study is to investigate the role and the underlying mechanisms of cyclin G2 on Wnt/β-catenin signaling in gastric cancer.MethodsReal-time PCR, immunohistochemistry and in silico assay were used to determine the expression of cyclin G2 in gastric cancer. TCGA datasets were used to evaluate the association between cyclin G2 expression and the prognostic landscape of gastric cancers. The effects of ectopic and endogenous cyclin G2 on the proliferation and migration of gastric cancer cells were assessed using the MTS assay, colony formation assay, cell cycle assay, wound healing assay and transwell assay. Moreover, a xenograft model and a metastasis model of nude mice was used to determine the influence of cyclin G2 on gastric tumor growth and migration in vivo. The effects of cyclin G2 expression on Wnt/β-catenin signaling were explored using a TOPFlash luciferase reporter assay, and the molecular mechanisms involved were investigated using immunoblots assay, yeast two-hybrid screening, immunoprecipitation and Duolink in situ PLA. Ccng2-/- mice were generated to further confirm the inhibitory effect of cyclin G2 on Wnt/β-catenin signaling in vivo. Furthermore, GSK-3β inhibitors were utilized to explore the role of Wnt/β-catenin signaling in the suppression effect of cyclin G2 on gastric cancer cell proliferation and migration.ResultsWe found that cyclin G2 levels were decreased in gastric cancer tissues and were associated with tumor size, migration and poor differentiation status. Moreover, overexpression of cyclin G2 attenuated tumor growth and metastasis both in vitro and in vivo. Dpr1 was identified as a cyclin G2-interacting protein which was required for the cyclin G2-mediated inhibition of β-catenin expression. Mechanically, cyclin G2 impacted the activity of CKI to phosphorylate Dpr1, which has been proved to be a protein that acts as a suppressor of Wnt/β-catenin signaling when unphosphorylated. Furthermore, GSK-3β inhibitors abolished the cyclin G2-induced suppression of cell proliferation and migration.ConclusionsThis study demonstrates that cyclin G2 suppresses Wnt/β-catenin signaling and inhibits gastric cancer cell growth and migration through Dapper1.

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Targeting Wnt/β-Catenin Signaling by TET1/FOXO4 Inhibits Metastatic Spreading and Self-Renewal of Cancer Stem Cells in Gastric Cancer.

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