MYCN and HIF-1 directly regulate <i>TET1</i> expression to control 5-hmC gains and enhance neuroblastoma cell migration in hypoxia
Creators: name: Hains, Anastasia E.
name: Uppal, Sakshi
name: Cao, John Z.
name: Salwen, Helen R.
name: Applebaum, Mark A.
name: Cohn, Susan L.
name: Godley, Lucy A.
Publisher: name: Taylor & Francis
Year: 2022
Subjects: subject: Biophysics
subject: Biochemistry
subject: Medicine
subject: Cell Biology
subject: Genetics
subject: FOS: Biological sciences
subject: Molecular Biology
subject: Neuroscience
subject: Physiology
subject: Immunology
subject: FOS: Clinical medicine
subject: Developmental Biology
subject: Marine Biology
subject: Cancer
subject: Hematology
subject: Infectious Diseases
subject: FOS: Health sciences
subject: Computational Biology

description: Ten-Eleven-Translocation 5-methylcytosine dioxygenases 1–3 (TET1-3) convert 5-methylcytosine to 5-hydroxymethylcytosine (5-hmC), using oxygen as a co-substrate. Contrary to expectations, hypoxia induces 5-hmC gains in <i>MYCN</i>-amplified neuroblastoma (NB) cells via upregulation of <i>TET1</i>. Here, we show that MYCN directly controls <i>TET1</i> expression in normoxia, and in hypoxia, HIF-1 augments <i>TET1</i> expression and TET1 protein stability. Through gene-editing, we identify two MYCN and HIF-1 binding sites within <i>TET1</i> that regulate gene expression. Bioinformatic analyses of 5-hmC distribution and RNA-sequencing data from hypoxic cells implicate hypoxia-regulated genes important for cell migration, including <i>CXCR4</i>. We show that hypoxic cells lacking the two MYCN/HIF-1 binding sites within <i>TET1</i> migrate slower than controls. Treatment of <i>MYCN-</i>amplified NB cells with a CXCR4 antagonist results in slower migration under hypoxic conditions, suggesting that inclusion of a CXCR4 antagonist into NB treatment regimens could be beneficial for children with <i>MYCN-</i>amplified NBs. In <i>MYCN-</i>amplified neuroblastoma cell lines, MYCN directly controls <i>TET1</i> expression in normoxia.In <i>MYCN-</i>amplified neuroblastoma cell lines exposed to hypoxia, HIF-1 augments <i>TET1</i> expression and TET1 protein stability.Hypoxic <i>MYCN-</i>amplified neuroblastoma cell lines have increased cell migration, mediated by genes including <i>CXCR4</i> that gain 5-hydroxymethylcytosine density.Treatment of <i>MYCN-</i>amplified NB cells with a CXCR4 antagonist slows hypoxia-associated migration, suggesting a CXCR4 antagonist could be beneficial in treatment regimens for children with <i>MYCN-</i>amplified neuroblastomas. In <i>MYCN-</i>amplified neuroblastoma cell lines, MYCN directly controls <i>TET1</i> expression in normoxia. In <i>MYCN-</i>amplified neuroblastoma cell lines exposed to hypoxia, HIF-1 augments <i>TET1</i> expression and TET1 protein stability. Hypoxic <i>MYCN-</i>amplified neuroblastoma cell lines have increased cell migration, mediated by genes including <i>CXCR4</i> that gain 5-hydroxymethylcytosine density. Treatment of <i>MYCN-</i>amplified NB cells with a CXCR4 antagonist slows hypoxia-associated migration, suggesting a CXCR4 antagonist could be beneficial in treatment regimens for children with <i>MYCN-</i>amplified neuroblastomas.