Identification of genes implicated in the resistance to treatment in Glioblastoma: focus on intracellular trafficking pathway

PhD thesis defended by Jia-Wei CHEN (Prof. Carine MICHIELS & Prof. Anne-Catherine HEUSKIN) - 07/09/2023

Prof. Carine MICHIELS, UNamur, Department of biology, Laboratory of Cellular and Molecular Biology (URBC) - promoter

Prof. Anne-Catherine HEUSKIN, UNamur, Department of physics, Laboratory of Analysis by Nuclear Reaction (LARN) - co-promoter

  • Prof. Charles NICAISE (URPhyM, UNamur), président
  • Prof. Carine MICHIELS (URBC, UNamur), promotrice et secrétaire
  • Prof. Anne-Catherine HEUSKIN (LARN, UNamur), co-promotrice
  • Prof. Lara Barazzuol (Department of Radiation Oncology, University of Groningen)
  • Prof. Pierre SONVEAUX (FATH, UCLouvain)
  • Prof. Thierry ARNOULD (URBC, UNamur)

Glioblastoma (GBM) is a highly aggressive brain tumor with limited treatment options and poor patient prognosis. Resistance to standard anti-cancer therapies contributes to treatment failure and tumor relapse. This study aimed to identify genes involved in GBM treatment resistance and to investigate their potential as therapeutic targets. To achieve this, we conducted a genome-scale CRISPR-Cas9 knockout screening in U87 GBM cells exposed to fractioned doses of X-rays combined with temozolomide (TMZ) treatment. The screening identified genes that selectively enhanced or reduced cell sensitivity to these treatments. The analysis revealed significant enrichment of genes involved in endosomal trafficking pathways, particularly those associated with the endosomal sorting complex required for transport (ESCRT) and the EH domain-binding protein 1 (EHBP1) as candidate genes. For the validation, lentiviral delivery of short hairpin RNA (shRNA) was used to knockdown the expression of ESCRT and EHBP1 candidate genes in GBM cells and the sensitivity to treatments was evaluated using clonogenic and propidium iodide staining assays. Results obtained could not completely validate the involvement of ESCRT components and EHBP1 in treatment sensitivity, further investigations are required to determine their potential implications. However, the identification of endosomal trafficking pathways is particularly intriguing as they play essential roles in diverse cellular processes such as receptor trafficking, cellular communication and cellular homeostasis. Targeting these pathways could hold promise as a potential strategy to enhance the sensitivity of GBM cells to anti-cancer treatments. Finally, the study highlights the use of patient-derived organoids as a valuable tool for studying GBM biology and treatment response. Organoids offer a valuable platform to explore, within a context that closely mimics physiological condition, the functional significance of identified candidate genes.