Dysregulation of microtubule dynamics caused by LOXL3 knockout triggers mitosis catastrophe and senescence in U87MG and U251 cells
The amine oxidase LOXL3 has been implicated in tumor development and progression, with elevated expression in glioblastoma (GBM). This enzyme influences GBM cell adhesion, migration, and proliferation, and is demonstrated correlation with tubulin expression. Microtubules, as the major component of the cytoskeleton, are crucial for cell cycle and mitotic progression. In this study, LOXL3 knockout was performed using CRISPR-Cas9 in two GBM cell lines, U87MG and U251, to achieve high silencing efficiency. The knockdown resulted in decreased cell viability in both cell lines. Transcriptome enrichment analysis of U87MG cells revealed downregulation of genes associated to tubulin acetylation, which was subsequently confirmed by Western blot analysis. Both U87MG and U251 cells exhibited downregulation of cell cycle and proliferation-related genes. Functional assays confirmed that LOXL3-knockout cells exhibited delayed cell cycle progression and significant alterations in mitotic spindles during metaphase-anaphase transition. Nuclear analysis revealed morphological changes indicative of mitotic catastrophe in U87MG cells and senescence in U251 cells. Additionally, LOXL3-knockout clones displayed reduced cell adhesion and migration. Interestingly, LOXL3 knockdown in GBM cell lines reduces tubulin acetylation, leading to mitotic catastrophe and subsequent cell death in a TP53 mutation-dependent manner. These findings highlight the potential of targeting LOXL3 as a combinatory strategy for advancing research and developing novel therapeutic approaches in TP53-mutated GBM. Overall design: RNAseq profiling of wilditype U87MG and U251 glioblastoma cells and their permanent LOXL3 knockdown (LOXL3-KD), through CRISPR-Cas9 system.