Time- and oxygen-dependent expression and regulation of NDRG1 in human brain cancer cells

Said,Harun Muayad; Safari,Roghaiyeh; Al-Kafaji,Ghada; Ernestus,Ralf-Ingo; Löhr,Mario; Katzer,Astrid; Flentje,Michael; Hagemann,Carsten

doi:10.3892/or.2017.5620

Time- and oxygen-dependent expression and regulation of NDRG1 in human brain cancer cells

Authors:
- Harun Muayad Said
- Roghaiyeh Safari
- Ghada Al-Kafaji
- Ralf-Ingo Ernestus
- Mario Löhr
- Astrid Katzer
- Michael Flentje
- Carsten Hagemann
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Affiliations: Department of Molecular Medicine, Graduate School of Health Sciences, Dokuz Eylul University, Izmir, Turkey, Izmir Biomedicine and Genome (IBG) Center, Dokuz Eylul University, Izmir, Turkey, Department of Molecular Medicine, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain, Department of Neurosurgery, University of Würzburg, Würzburg, Germany, Department of Radiation Oncology, University of Würzburg, Würzburg, Germany
Published online on: May 3, 2017 https://doi.org/10.3892/or.2017.5620
Pages: 3625-3634

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Abstract

N-myc downstream-regulated gene 1 (NDRG1) is a tumor suppressor with the potential to suppress metastasis, invasion and migration of cancer cells. It is regulated under stress conditions such as starvation or hypoxia. NDRG1 regulation is both induced and controlled by HIF-1α-dependent and -independent pathways under hypoxic conditions. However, there are profound differences in the way NDRG1 expression is regulated by HIF-1α and other transcription factors. Therefore, we aimed to define the time-dependent pattern of NDRG1 mRNA and protein expression in human glioblastoma cell lines in extreme hypoxia and after re-oxygenation as well as under normoxic conditions. Furthermore, we ascribe the regulation of NDRG1 to the transcription factors HIF-1α, SP1, CEBPα, YB-1 and Smad7 in a time-dependent manner. The human malignant glioma cell lines U87-MG, U373 and GaMG were cultured for 1, 6 and 24 h under hypoxic (0.1% O2) conditions and then they were re-oxygenated. The mRNA expression of NDRG1, HIF-1α SP1, CEBPα, YB-1 and Smad7 was measured using semi-quantitative RT-PCR analysis. Their protein expression was analyzed using western blotting. Our experiments revealed that long-term (24 h), but not short-term hypoxia led to the induction of NDRG1 expression in human glioma cell lines. NDRG1 expression was found to correlate with the protein expression of HIF-1α, SP1, CEBPα, YB-1 and Smad7. The present study suggests for the first time that SP1 regulates NDRG1 expression in glioma cells under hypoxia in a time-dependent manner along with HIF-1α, CEBPα, YB-1 and Smad7. These molecules, each separately or in combination, may possess the potential to become target molecules for antitumor therapeutic approaches particularly in human brain tumors.

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