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Role of ZBTB18 Tumor Suppression in Glioblastoma Progression
Marzieh Hesam Mohammadi
Affiliation: Faculty of Pharmacy and Biochemistry, University of Buenos Aires, Argentina and Faculty of Medicine, University of Freiburg, Germany
Keywords: Glioblastoma, ZBTB18, SREBP Pathway, Tumor Suppressor, CRISPR/Cas9 Knockdown
Categories: Medicine, Demetrios Project
DOI: 10.17160/josha.11.6.1011
Languages: English
Glioblastoma (GBM) is the most frequent and most malignant human brain tumor which consists of distinct subtypes characterized by their gene expression profile. The Zinc Finger and BTB Domain Containing 18 (ZBTB18) is a transcriptional repressor that plays a crucial role in brain development and neuronal differentiation. A previous study in Carro 's group provided evidence of the role of ZBTB18 in a network of transcription factors that control mesenchymal transformation in GBM. More recently, our group displayed that ZBTB18 overexpression leads to a loss of the mesenchymal and proliferative signatures and downregulation of an array of genes involved in glioblastoma tumorigenesis. These surveys support the role of ZBTB18 as a tumor suppressor in GBM and raise further questions as to how this is carried out in different tumor samples. Our project "Role of ZBTB18 tumor suppressor in Glioblastoma progression" pointed out to describe some of the mechanisms by which ZBTB18 targets lead to glioblastoma progression. This study aims at better defining the significance of SREBP pathway activation in glioblastoma and its potential involvement in the previously observed ZBTB18 tumor suppressive function. To achieve this goal, we attempted to treat various Brain Tumor Stem-like Cells (BTSC) (BTSC168 and BTSC233 cells) with oxLDL which has been reported to activate the SREBP pathway. To determine the correct conditions for oxLDL treatment, we first set up a time-course experiment and analyzed the expression of several SREBP genes by qPCR. This experiment due to technical reasons that still need to be clarified, did not allow us to rule out whether ZBTB18-mediated downregulation of SREBP genes is important for ZBTB18 tumor suppressor activity. We then planned to analyze in more detail the ZBTB18 function by performing CRISPR/Cas9 knockdown in the BTSC475 cells which express ZBTB18. Interestingly, ZBTB18 knockdown positively regulated a subset of SREBP genes. In line with our findings, we observed an increase of lipid droplets upon ZBTB18 knockdown; the overall metabolism, however, was not particularly affected. Finally, as LSD1 and HDAC are implicated in SREBP activation, we investigated the effect of Corin inhibition of HDAC and LSC1 which has been shown to act as a dual inhibitor. qPCR analysis revealed that Corin negatively regulates SREBP genes and affects the rate of ATP production. Given the lack of effective therapies for GBM, more studies on the linkage between the role of ZBTB18 and fatty acids synthesis in tumorigenesis could have future therapeutical applications.