Temozolomide promotes glioblastoma stemness expression through senescence-associated reprogramming via HIF1α/HIF2α regulation

A critical challenge in glioblastoma multiforme (GBM) treatment is that tumors recurring after temozolomide (TMZ) therapy become more malignant, exhibiting increased invasiveness and stemness compared to the primary tumor. However, the underlying mechanisms remain unclear. While the majority of GBM cells are eradicated by TMZ, a subset enters cell cycle arrest, adopts a senescence-associated secretory phenotype (SASP), and activates senescence-related signaling pathways. These cells eventually escape senescence, re-enter the cell cycle, and form aggregates exhibiting stem-like characteristics such as elevated stemness marker expression, enhanced colony formation, increased invasiveness, and resistance to chemotherapy. Furthermore, these aggregates promote the invasion and chemotherapy resistance of surrounding cells. Gene Set Enrichment Analysis (GSEA) and KEGG pathway analysis of miRNA and mRNA sequences revealed activation of hallmark hypoxia and HIF1 signaling pathways. The study demonstrated that HIF1α and HIF2α expression fluctuates during and after TMZ treatment. Knockout of HIF1α and HIF2α in GBM cells exposed to TMZ reduced the formation of senescent cells and stem-like aggregates. These findings challenge the efficacy of TMZ therapy by highlighting its role in inducing the process of cellular senescence, thereby contributing to the enhanced stemness and malignancy of recurrent GBM. The regulatory roles of HIF1α and HIF2α are emphasized, underscoring the necessity of preventing senescent cell formation and inhibiting HIF1α/HIF2α expression to improve therapeutic outcomes.